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Sample records for expiratory flow limitation

  1. Physiological techniques for detecting expiratory flow limitation during tidal breathing

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    N.G. Koulouris

    2011-09-01

    Full Text Available Patients with severe chronic obstructive pulmonary disease (COPD often exhale along the same flow–volume curve during quiet breathing as they do during the forced expiratory vital capacity manoeuvre, and this has been taken as an indicator of expiratory flow limitation at rest (EFLT. Therefore, EFLT, namely attainment of maximal expiratory flow during tidal expiration, occurs when an increase in transpulmonary pressure causes no increase in expiratory flow. EFLT leads to small airway injury and promotes dynamic pulmonary hyperinflation, with concurrent dyspnoea and exercise limitation. In fact, EFLT occurs commonly in COPD patients (mainly in Global Initiative for Chronic Obstructive Lung Disease III and IV stage, in whom the latter symptoms are common, but is not exclusive to COPD, since it can also be detected in other pulmonary and nonpulmonary diseases like asthma, acute respiratory distress syndrome, heart failure and obesity, etc. The existing up to date physiological techniques of assessing EFLT are reviewed in the present work. Among the currently available techniques, the negative expiratory pressure has been validated in a wide variety of settings and disorders. Consequently, it should be regarded as a simple, noninvasive, practical and accurate new technique.

  2. Circulatory effects of expiratory flow-limited exercise, dynamic hyperinflation and expiratory muscle pressure

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    P. T. Macklem

    2006-12-01

    Full Text Available This article reviews recent research in normal subjects exercising with and without expiratory flow limitation at 1 L·s–1 imposed by a Starling resistor in the expiratory line, and in patients with chronic obstructive pulmonary disease (COPD, using optoelectronic plethysmography to measure respiratory kinematics, combined with mouth, pleural and abdominal pressure measurements, to assess work of breathing and respiratory muscle performance. In normal subjects, flow-limited exercise resulted in the following: 1 Impaired exercise performance due to intolerable dyspnoea; 2 hypercapnia; 3 excessive respiratory muscle recruitment; 4 blood shifts from trunk to extremities; 5 a 10% reduction in cardiac output and a 5% reduction in arterial oxygen saturation, decreasing energy supplies to working respiratory and locomotor muscles. In both normal subjects and in COPD patients, dynamic hyperinflation did not always occur. Those patients that hyperinflated had worse lung function and less work of breathing, but better exercise performance than the others, in whom expiratory muscle recruitment prevented dynamic hyperinflation at the cost of increased work of breathing and excessive oxygen cost of breathing. This established an early competition between respiratory and locomotor muscles for available energy supplies. Dynamic hyperinflation is a better exercise strategy in chronic obstructive pulmonary disease than expiratory muscle recruitment, but the benefit it confers is small.

  3. Methods for Assessing Expiratory Flow Limitation during Tidal Breathing in COPD Patients

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    Nickolaos G. Koulouris

    2012-01-01

    Full Text Available Patients with severe COPD often exhale along the same flow-volume curve during quite breathing as during forced expiratory vital capacity manoeuvre, and this has been taken as indicating expiratory flow limitation at rest (EFLT. Therefore, EFLT, namely, attainment of maximal expiratory flow during tidal expiration, occurs when an increase in transpulmonary pressure causes no increase in expiratory flow. EFLT leads to small airway injury and promotes dynamic pulmonary hyperinflation with concurrent dyspnoea and exercise limitation. In fact, EFLT occurs commonly in COPD patients (mainly in GOLD III and IV stage in whom the latter symptoms are common. The existing up-to-date physiological methods for assessing expiratory flow limitation (EFLT are reviewed in the present work. Among the currently available techniques, the negative expiratory pressure (NEP has been validated in a wide variety of settings and disorders. Consequently, it should be regarded as a simple, non invasive, most practical, and accurate new technique.

  4. Expiratory flow limitation and operating lung volumes during exercise in older and younger adults.

    Science.gov (United States)

    Smith, Joshua R; Kurti, Stephanie P; Meskimen, Kayla; Harms, Craig A

    2017-06-01

    We determined the effect of aging on expiratory flow limitation (EFL) and operating lung volumes when matched for lung size. We hypothesized that older adults will exhibit greater EFL and increases in EELV during exercise compared to younger controls. Ten older (5M/5W; >60years old) and nineteen height-matched young adults (10M/9W) were recruited. Young adults were matched for%predicted forced vital capacity (FVC) (Y-matched%Pred FVC; n=10) and absolute FVC (Y-matched FVC; n=10). Tidal flow-volume loops were recorded during the incremental exercise test with maximal flow-volume loops measured pre- and post-exercise. Compared to younger controls, older adults exhibited more EFL at ventilations of 26, 35, 51, and 80L/min. The older group had higher end-inspiratory lung volume compared to Y-matched%Pred FVC group during submaximal ventilations. The older group increased EELV during exercise, while EELV stayed below resting in the Y-matched%Pred FVC group. These data suggest older adults exhibit more EFL and increase EELV earlier during exercise compared to younger adults. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. Peak expiratory flow rate and Pulse Pressure values during the ...

    African Journals Online (AJOL)

    This study assessed the peak expiratory flow rate and pulse pressure during the luteal and menstruation phases of the menstrual cycle. The peak expiratory flow rate and pulse pressure were measured using the Wright's Peak Flow Meter and Mercury Sphygmomanometer respectively. The peak expiratory flow rate and ...

  6. Physiological and morphological determinants of maximal expiratory flow in chronic obstructive lung disease

    NARCIS (Netherlands)

    H.A.W.M. Tiddens (Harm); J.M. Bogaard (Jan); J.C. de Jongste (Johan); W.C.J. Hop (Wim); H.O. Coxson (Harvey); P.D. Pare

    1996-01-01

    textabstractMaximal expiratory flow in chronic obstructive pulmonary disease (COPD) could be reduced by three different mechanisms; loss of lung elastic recoil, decreased airway conductance upstream of flow-limiting segments; and increased collapsibility of airways.

  7. Peak Expiratory Flow Rate In Cigarette Smokers | Ukoli | Highland ...

    African Journals Online (AJOL)

    Objective: To compare lung function between smokers and non-smokers using Peak Expiratory Flow Rate (PEFR). Methods: This study examines the peak expiratory flow rate (PEFR) of three hundred and forty cigarette smokers, age and sex-matched with PEFR of equal number of non-smokers. Results: The mean PEFR of ...

  8. Superoxide dismutase levels and peak expiratory flow in asthmatic children

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    Arie Kurniasih

    2016-11-01

    Full Text Available Background Asthma is a chronic inflammatory process which involve variety of cells such as inflammatory mediators, reactive oxygen species (ROS, and cytokines. The inflammatory process would be exacerbated in the presence of oxidative stress. Superoxide dismutase (SOD is the first important enzyme to protect the respiratory tract against oxidative stress. The decreased of SOD has a correlation with increased of airway obstruction and bronchospasm. Objective To assess for a correlation between superoxide dismutase (SOD levels and peak expiratory flow, as well as to determine the impact of SOD levels for predicting asthma attacks. Methods We conducted a prospective cohort study at Dr. Sardjito Hospital, Yogyakarta, between February and April 2011 involving asthmatic children aged 5-18 years. Subjects’ serum SOD levels and peak expiratory flow were measured at the same time point. We then performed a prospective study following up on the same subjects to find out if they had a recurrent asthma attack within one month of the tests. We also reassessed their peak expiratory flow one month after blood specimens were obtained. Results Thirty-nine patients were enrolled in this study. There was no significant correlation between SOD level and peak expiratory flow [r=0.289; 95%CI -0.025 to 0.47; P=0.074]. However, older age was significantly associated with higher peak expiratory flow (=0.5; 95%CI 3.10 to 11.57; P=0.01. Lower levels of SOD increased the risk of asthma attacks in a month following the initial measurements (RR=5.5; 95%CI 1.6 to 18.9; P=0.009. Conclusion Superoxide dismutase (SOD level is not significantly associated with peak expiratory flow. However, we find a relationship between older age and higher peak expiratory flow and a relationship between lower SOD levels and risk of asthma attacks within one month following the tests.

  9. Variant formula for predicting peak expiratory flow rate in pregnant ...

    African Journals Online (AJOL)

    Observed Peak expiratory flow rate (PEFR), Predicted and Variant PEFR values in 123 females at their reproductive ages, living in Kura local government area of Kano State, Nigeria and its environs were obtained. The prediction and variant formulae used were; PEFR= 0.36AGE – 0.47WT + 391.67 and K = mean CC x ...

  10. predicted peak expiratory flow in human and the clinical implication ...

    African Journals Online (AJOL)

    DR. AMINU

    values using formula developed by (Gregg, 1973) at 50th percentile for age, height and weight obtained from our study (Salisu ... Keywords: Peak expiratory flow, Asthma, Practice guidelines, reference values. INTRODUCTION. The National ... that the personal best PEF may be estimated after a. 2-to-3-week period in which ...

  11. Peak expiratory flow rate and respiratory symptoms following ...

    African Journals Online (AJOL)

    Peak expiratory flow rate (PEFR) of 350 rural women aged (20-70 years) in Edo State, Nigeria who actively used wood as a source of fuel for cooking was measured. The height, chest circumference, weight and blood pressure of the women were also measured. Respiratory symptoms of cough with sputum production, ...

  12. Factors influencing peak expiratory flow in teenage boys | van ...

    African Journals Online (AJOL)

    Background. Peak expiratory flow (PEF) is a useful measure of pulmonary health status and is frequently utilised in asthm, management. Reduction in PEF is usually indicative of OIlS( of asthma symptoms. However, use can be made of PEF values only if normal values are known. The definition of normal range is always ...

  13. Peak Expiratory Flow Rate in Petroleum Depot Workers and Petrol ...

    African Journals Online (AJOL)

    Peak Expiratory Flow Rate (PEFR) values in litres per minute were determined in petrol depot loaders, petrol station attendants and in control subjects. The PEFR values were 315 ± 94, 386 + 91 and 529 + 94 litres/min. in depot workers, petrol attendants and control subjects respectively. The value in the control subjects ...

  14. variant formula for predicting peak expiratory flow rate in pregnant ...

    African Journals Online (AJOL)

    DR. AMINU

    The graph illustrates close association of variant formula with the observed values of PEFR obtained from the study. Variant formula may be useful in clinical setting to assess people with respiratory disorders especially asthma. Key words: Variant formula, Peak expiratory flow rate, Pregnancy, Kura local government area.

  15. Changes in Peak Expiratory Flow Rate, Blood Pressure and Pulse ...

    African Journals Online (AJOL)

    We studied the effect of different concentrations of coffee on peak expiratory flow rate (PEFR), blood pressure and pulse rate in an attempt to determine some physiological effects of coffee intake. 18 apparently healthy adult males, age range 20 to 30 years, were recruited for the study over a three day period. Varying ...

  16. Limitation of measurements of expiratory tidal volume and expiratory compliance under conditions of endotracheal tube leaks.

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    Herber-Jonat, Susanne; von Bismarck, Philipp; Freitag-Wolf, Sandra; Nikischin, Werner

    2008-01-01

    Endotracheal tube leaks (ETTLs) occur in neonates ventilated with uncuffed tubes. Assuming that the influence of ETTLs might be neglected during expiration, only expiratory tidal volume is measured for calculation of expiratory compliance in cases of large ETTLs. However, expiratory ETTL might be substantial. Therefore, we evaluated the effect of ETTL size on expiratory tidal volume and compliance. Prospective laboratory study and retrospective clinical study. University research laboratory and neonatal intensive care unit. Sixty ventilated neonates (weight 640-2160 g, gestational age 25-33 wks) were investigated. The impact of increasing ETTLs on inspiratory and expiratory measured tidal volume (Vm), corrected tidal volume (Vc), and leak volume (Vl) was investigated in a ventilated neonatal lung model. The range of ETTLs (1% to 95%) was subdivided into five groups of 12 infants each. Furthermore, the relationships between standard ETTL size and inspiratory and expiratory ETTLs were evaluated using nonlinear regression. Standard ETTL size was defined as the difference between measured inspiratory and expiratory tidal volume (Vm) related to inspiratory Vm. The size of a standard ETTL was 40% when expiratory ETTL reached 10% and was 12% when the inspiratory ETTL reached 10%. In infants, the differences between Vm and Vc were statistically significant during inspiration in the group beginning at a standard ETTL of 41% and during expiration in the group beginning at a standard ETTL of 69% (p ETTL was 33% (95% confidence interval, 28% to 36%) when expiratory ETTL reached 10% and was 13% (95% confidence interval, 12% to 15%) when inspiratory ETTL reached 10%. Expiratory Vl has a relevant impact if a certain ETTL size is reached.

  17. The Concave Shape of the Forced Expiratory Flow-Volume Curve in 3 Seconds Is a Practical Surrogate of FEV1/FVC for the Diagnosis of Airway Limitation in Inadequate Spirometry.

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    Li, Hao; Liu, Chunhong; Zhang, Yi; Xiao, Wei

    2017-03-01

    Spirometry is important for the differential diagnosis of dyspnea. However, some patients cannot exhale for ≥6 s to achieve the American Thoracic Society/European Respiratory Society criteria. The aim of this study was to demonstrate the reliability of a new parameter that quantifies the degree of concavity in the first 3 s to define airway limitation as a surrogate for the FEV 1 /FVC. Four hundred spirometry test results were selected through complete random sampling. The new parameter, termed the AUC 3 /AT 3 , was calculated as the area under the descending limb of the expiratory flow-volume curve before the end of the first 3 s (AUC 3 ) divided by the area of the triangle before the end of the first 3 s (AT 3 ). The AUC 3 /AT 3 was compared with the FEV 1 /FVC using Pearson's correlation analysis. The level of agreement between the AUC 3 /AT 3 and the FEV 1 /FVC in the detection of airway obstruction was analyzed using the kappa statistic. We also compared the diagnostic accuracy of the new index with that of the FEV 1 /forced expiratory volume in the first 3 s (FEV 3 ). There was a strong correlation (r = 0.88, P < .001) between the AUC 3 /AT 3 and the FEV 1 /FVC. There was also strong agreement between the AUC 3 /AT 3 and the FEV 1 /FVC in the detection of obstruction with kappa indices of 0.72 (Global Initiative for Chronic Obstructive Lung Disease [GOLD] criterion) and 0.67 (lower limit of normal criterion), and these values were greater than those obtained for the FEV 1 /FEV 3 . The AUC 3 /AT 3 also exhibited acceptable sensitivity, specificity, positive predictive value, and negative predictive value. The diagnostic accuracies of the AUC 3 /AT 3 were 86.3% (GOLD criterion) and 83.8% (lower limit of normal criterion), which were greater than the 76.0 and 74.0% obtained for the FEV 1 /FEV 3 , respectively. The AUC 3 /AT 3 can be utilized as a surrogate parameter for the FEV 1 /FVC when patients cannot complete a 6-s expiratory effort. Additionally, the

  18. Physiological and morphological determinants of maximal expiratory flow in chronic obstructive lung disease

    OpenAIRE

    Tiddens, Harm; Bogaard, Jan; Jongste, Johan; Hop, Wim; Coxson, Harvey; Pare, P.D.

    1996-01-01

    textabstractMaximal expiratory flow in chronic obstructive pulmonary disease (COPD) could be reduced by three different mechanisms; loss of lung elastic recoil, decreased airway conductance upstream of flow-limiting segments; and increased collapsibility of airways. We hypothesized that decreased upstream conductance would be related to inflammation and thickening of the airway walls, increased collapsibility would be related to decreased airway cartilage volume, and decreased collapsibility ...

  19. [Cerebral blood flow assessment of preterm infants during respiratory therapy with the expiratory flow increase technique].

    Science.gov (United States)

    Bassani, Mariana Almada; Caldas, Jamil Pedro Siqueira; Netto, Abimael Aranha; Marba, Sérgio Tadeu Martins

    2016-06-01

    To assess the impact of respiratory therapy with the expiratory flow increase technique on cerebral hemodynamics of premature newborns. This is an intervention study, which included 40 preterm infants (≤34 weeks) aged 8-15 days of life, clinically stable in ambient air or oxygen catheter use. Children with heart defects, diagnosis of brain lesion and/or those using vasoactive drugs were excluded. Ultrasonographic assessments with transcranial Doppler flowmetry were performed before, during and after the increase in expiratory flow session, which lasted 5minutes. Cerebral blood flow velocity and resistance and pulsatility indices in the pericallosal artery were assessed. Respiratory physical therapy did not significantly alter flow velocity at the systolic peak (p=0.50), the end diastolic flow velocity (p=0.17), the mean flow velocity (p=0.07), the resistance index (p=0.41) and the pulsatility index (p=0.67) over time. The expiratory flow increase technique did not affect cerebral blood flow in clinically-stable preterm infants. Copyright © 2015 Sociedade de Pediatria de São Paulo. Publicado por Elsevier Editora Ltda. All rights reserved.

  20. Cerebral blood flow assessment of preterm infants during respiratory therapy with the expiratory flow increase technique

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    Mariana Almada Bassani

    2016-06-01

    Full Text Available Abstract Objective: To assess the impact of respiratory therapy with the expiratory flow increase technique on cerebral hemodynamics of premature newborns. Methods: This is an intervention study, which included 40 preterm infants (≤34 weeks aged 8-15 days of life, clinically stable in ambient air or oxygen catheter use. Children with heart defects, diagnosis of brain lesion and/or those using vasoactive drugs were excluded. Ultrasonographic assessments with transcranial Doppler flowmetry were performed before, during and after the increase in expiratory flow session, which lasted 5min. Cerebral blood flow velocity and resistance and pulsatility indices in the pericallosal artery were assessed. Results: Respiratory physical therapy did not significantly alter flow velocity at the systolic peak (p=0.50, the end diastolic flow velocity (p=0.17, the mean flow velocity (p=0.07, the resistance index (p=0.41 and the pulsatility index (p=0.67 over time. Conclusions: The expiratory flow increase technique did not affect cerebral blood flow in clinically-stable preterm infants.

  1. Decreased peak expiratory flow in pediatric passive smokers

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    Fitri Yanti

    2011-08-01

    Full Text Available Background Indonesia ranks fifth among countries with the highest aggregate levels of tobacco consumption in the world. Infants and children exposed to environmental tobacco smoke have increased rates of asthma, respiratory and ear infections, as well as reduced lung function. The effects of tobacco smoke exposure on lung function in children have been reported to be dependent on the source of smoke and the length and dose of exposure. Lung function may also be affected by a child’s gender and asthma status. Objective To compare peak expiratory flow (PEF in pediatric passive smokers to that of children not exposed to second hand smoke, and to define factors that may affect PEF in passive smokers. Methods In August 2009 we conducted a cross-sectional study at an elementary school in the Langkat district. Subjects were aged 6 to 12 years, and divided into two groups: passive smokers and those not exposed to secondhand smoke. Subjects’ PEFs were measured with a Mini-Wright peak flow meter. Measurements were performed in triplicate with the highest value recorded as the PEF. Demographic data including age, sex, weight, height, family income, parental education levels and occupations were obtained through questionnaires. Results Of the 170 participants, 100 were passive smokers and 70 were not exposed to secondhand smoke. Age distribution, weight and height were similar in both groups. We observed a significant difference in PEFs between the group of passive smokers and the group not exposed to secondhand smoke, 211.3 L/minute (SD 61.08 and 242.7 L/minute (SD 77.09, respectively (P < 0.005. The number of years of exposure to smoke (P = 0.079 and the number of cigarettes smoked daily in the household (P = 0.098 did not significantly influence PEF. Conclusion The PEF in pediatric passive smokers was significantly lower than that of children not exposed to secondhand smoke. PEF in passive smokers was not influenced by the number of years of smoke

  2. PEAK EXPIRATORY FLOW AS A SURROGATE FOR HEALTH ...

    African Journals Online (AJOL)

    2014-06-01

    Jun 1, 2014 ... Proportions reported are based on the entire sample of patients. Sixty five percent of the patients had peak flow read- ings below the acceptable lower limit of normal (LLN) for their age and height (Table 2). The mean (SD) of predicted post bronchodilator (post BD) PEF, FEV1,. FVC and FEV1/FVC were ...

  3. Effect of variable circuit flow rate during the expiratory phase on CO2 elimination

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    Keszler PA

    2012-05-01

    Full Text Available Peter A Keszler,1 Pankaj Nagaraj,1 Kabir Abubakar,1 Martin Keszler21Georgetown University, Washington, DC, USA; Georgetown University Hospital, Washington, DC, USA; 2Brown University, Women and Infants Hospital of Rhode Island, Providence, RI, USABackground: Some continuous flow infant ventilators allow independent setting of inspiratory and expiratory circuit flow rate. In the Dräger Babylog 8000+ ventilator, this is called "variable inspiratory, variable expiratory flow" (VIVE. Some clinicians believe that lower expiratory flow decreases expiratory resistance. The minimum expiratory flow rate needed to avoid re-breathing of carbon dioxide (CO2 has never been established.Objective: We sought to determine if re-breathing becomes evident at the lowest possible expiratory flow rate setting of 1 L/min.Design/methods: We conducted a bench study using end-tidal CO2 (ETCO2 measurement and a 45 mL (90 mL for the "term" model test lung pre-filled with 100% CO2. We previously showed that the time needed for ETCO2 to be eliminated from the lung is a highly reproducible indicator of efficiency of ventilation. Re-breathing would thus be identified by an increase in the time required for the CO2 to be washed out from the test lung at stable settings of rate and tidal volume (VT. Using a Babylog 8000+ ventilator in volume guarantee mode with VIVE and a standard ventilator circuit, we tested the effect of decreasing expiratory flow rate under conditions simulating three sizes of patients: extremely low birth weight infant, wt = 600 g (VT = 3.5 mL, respiratory rate (RR = 60 breaths min-1, minute ventilation (MV = 210 mL/min, expiratory flow rate = 3 L/min, 2 L/min, and 1 L/min, very low birth weight infant, wt = 1.5 kg (VT= 7 mL, RR = 60 breaths min-1, MV = 420 mL/min, expiratory flow rate = 4 L/min, 3 L/min, 2 L/min, and 1 L/min, and term infant, wt = 3.6 kg (VT = 16 mL, RR = 60 breaths min-1, MV = 960 mL/min, expiratory flow rate = 5 L/min, 4 L/min, 3 L

  4. Relative impact of respiratory muscle activity on tidal flow and end expiratory volume in healthy neonates

    NARCIS (Netherlands)

    Hutten, Gerard J.; van Eykern, Leo A.; Latzin, Philipp; Kyburz, Manuela; van Aalderen, Wim M.; Frey, Urs

    2008-01-01

    Introduction: It has been suggested that infants dynamically regulate their tidal flow and end-expiratory volume level. The interaction between muscle activity, flow and lung volume in spontaneously sleeping neonates is poorly studied, since it requires the assessment of transcutaneous

  5. Peak expiratory flow rates produced with the Laerdal and Mapleson-C bagging circuits.

    Science.gov (United States)

    Jones, A; Hutchinson, R; Lin, E; Oh, T

    1992-01-01

    This study compared the peak expiratory flow rates (PEFR) at different inspiratory pause pressures (IPP) produced by the Mapleson-C circuit and the Laerdal self-inflating resuscitator. The difference in PEFR produced by the two circuits was significantly different at the lowest and the highest IPP studied (I3 and 38cm H20). The greatest differences in the mean expiratory flow rates produced was, however, only 0.07 litre sec(-7). The authors suggest that the choice of bagging circuit should depend on the experience and familiarity of the therapist with the circuit. Copyright © 1992 Australian Physiotherapy Association. Published by . All rights reserved.

  6. A study of diurnal variation in peak expiratory flow rates in healthy adult female subjects in South India

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    Jenny Jayapal

    2014-01-01

    Full Text Available Background: Peak Expiratory Flow Rate (PEFR reflects the strength and condition of respiratory muscles and the degree of airflow limitation in large airways. PEFR shows hour to hour variation that follows a specific pattern in asthmatics and healthy individuals. Adequate data is not available for the diurnal variation in normal individuals who are students in professional courses and had a sedentary life style. Hence, this study was undertaken to study the diurnal variation in peak expiratory flow rates in healthy adult female subjects in South India. Materials and Methods: Peak expiratory flow rate was recorded in 50 adult healthy female students aged 18-23 years and studying in professional courses. Mini Wright′s peak flow meter was used to measure the peak expiratory flow rate. PEFR were recorded at 7-8 a.m., 10-11 a.m., 1-2 p.m., 4-5 p.m., and 7-8 p.m. for two consecutive days. Results: On analysis of PEFR records of individual subjects, it was seen that there was an overall dip in the morning at 7-8 h PEFR, which increased in the daytime, peaking in the afternoon at 1-2 p.m. and eventually decreased in the night. Subjects did not show the peak PEFR values at the same time point, 10% of subjects had a rise in PEFR in the early morning, afternoon (1-2 p.m. peak was observed in 48% subjects and evening (4-5 p.m. peak was observed in 16% subjects. 14% subjects showed a peak in the night time (7-8 p.m. PEFR values. Conclusion: This study provided the preliminary reference data of diurnal variation of peak expiratory flow rate in healthy adults. Since, there is a variation in the peak expiratory flow rate recorded during different time points of the day; hence, to compare the PEFR between individuals it is advisable to record the PEFR at the same time point.

  7. PROGRESSIVE MUSCLE RELAXATION INCREASE PEAK EXPIRATORY FLOW RATE ON CHRONIC OBSTRUCTIVE PULMONARY DISEASE PATIENTS

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    Tintin Sukartini

    2017-07-01

    Full Text Available Introduction: Limited progressive air flow in Chronic Obstructive Pulmonary Disease (COPD can caused by small airway disease (bronchiolitis obstructive and loss of elasticity of the lung (emphysema. Further it can be decreasing the quality of life in COPD patients because dyspnea and uncomfortable in activity. Progressive muscle relaxation (PMR is one of the relaxation technique that can repair pulmonary ventilation by decreasing chronic constriction of the respiratory muscles. The objective of this study was to analyze the effect of progressive muscle relaxation on raised peak expiratory flow rate (PEFR. Method: A pre-experimental one group pre-post test design was used in this study. Population was all of the COPD patients at Pulmonary Specialist Polyclinic Dr Mohamad Soewandhie Surabaya. There were 8 respondents taken by using purposive sampling. PEFR was counted by using peak flow meter every six day. Data were analyzed by using Paired t-Test with significance level  p≤0.05. Result: The result showed that PMR had significance level on increasing of PEFR (p=0.012. Discussion: It can be concluded that PMR has an effect on raise PEFR. Further studies are recommended to measure the effect of PMR on respiratory rate (RR, heart rate (HR subjective dyspnoe symptoms, forced expiration volume on the first minute (FEV1 and mid maximum flow rate (MMFR in COPD patients.

  8. Exogenous stimuli and circadian peak expiratory flow variation in allergic asthmatic children

    NARCIS (Netherlands)

    Postma, DS; VanderHeide, S; DeReus, DM; Koeter, GH; VanAalderen, WMC; Meijer, G.

    The influence of exogenous factors in the home on the circadian variation of airway obstruction has not been fully assessed in children with asthma. The aim of the present study was to investigate the contribution of exogenous stimuli to the degree of peak expiratory flow (PEF) variability during 24

  9. variations of peak expiratory flow rate with anthropometric

    African Journals Online (AJOL)

    admin

    Decreased bronchomotor tone would lead to a fall in airway resistance, and hence increased flow rate of air along it. Tests of. PEFR reflect changes in airway calibers. (Hughes and Empey, 1981). There have been reports on the variations of various ventilatory parameters with anthropometric determinants in. Nigerians.

  10. 16 reference population equations using peak expiratory flow meters

    African Journals Online (AJOL)

    DR. AMINU

    Many formulae for predicting lung function values for Nigerians have been produced by a lot of investigators. The same principle ... equations in current use are based on linear statistical models which are subject to change and they did not express the .... that present lower limits of normal or present information from which ...

  11. Effects of manual rib cage compressions on expiratory flow and mucus clearance during mechanical ventilation.

    Science.gov (United States)

    Martí, Joan Daniel; Li Bassi, Gianluigi; Rigol, Montserrat; Saucedo, Lina; Ranzani, Otavio Tavares; Esperatti, Mariano; Luque, Nestor; Ferrer, Miquel; Vilaro, Jordi; Kolobow, Theodor; Torres, Antoni

    2013-03-01

    We investigated the effects of two different types of manual rib cage compression on expiratory flow and mucus clearance during prolonged mechanical ventilation in pigs. Prospective randomized animal study. Animal research facility, University of Barcelona, Spain. Nine healthy pigs. Pigs were tracheally intubated, sedated, paralyzed, and mechanically ventilated. The animals were prone on a surgical bed in the anti-Trendelenburg position. The experiments were carried out at approximately 60 and 80 hrs from the beginning of mechanical ventilation. Two types of manual rib cage compressions were tested: Hard and brief rib cage compressions synchronized with early expiratory phase (hard manual rib cage compression) and soft and gradual rib cage compressions applied during the late expiratory phase (soft manual rib cage compression). The interventions were randomly applied for 15min with a 15-min interval between treatments. Respiratory flow and mucus movement were assessed during the interventions. Respiratory mechanics and hemodynamics were assessed prior to and after the interventions. Peak expiratory flow increased to 60.1±7.1L/min in comparison to 51.2±4.6L/min without treatment (p < 0.0015) and 48.7±4.3L/min with soft manual rib cage compression (p = 0.0002). Similarly, mean expiratory flow increased to 28.4±5.2L/min during hard manual rib cage compression vs. 15.9±2.2 and 16.6±2.8L/min without treatment and soft manual rib cage compression, respectively (p = 0.0006). During hard manual rib cage compression, mucus moved toward the glottis (1.01 ± 2.37mm/min); conversely, mucus moved toward the lungs during no treatment and soft manual rib cage compression, -0.28 ± 0.61 and -0.15±0.95mm/min, respectively (p = 0.0283). Soft manual rib cage compression slightly worsened static lung elastance and cardiac output (p = 0.0391). Hard manual rib cage compression improved mucus clearance in animals positioned in the anti-Trendelenburg position. The technique

  12. Thoracoabdominal mobility evaluation by photogrammetry in newborns after expiratory flow increase technique

    Directory of Open Access Journals (Sweden)

    Júlia Isabel de Araújo Guerra

    Full Text Available Abstract Introduction: Expiratory flow increase is a maneuver of respiratory physical therapy that promotes flow direction to the upper airways however, when applied in newborns, it may result in changes of thoracoabdominal mobility. Objective: To evaluate the thoracoabdominal mobility by photogrammetry in newborns after expiratory flow increase technique. Methods: Experimental blind study performed with newborns in supine position on a support table with upper limbs flexed, abducted and externally rotated and hip flexed at 110°. Adhesive markers were allocated for geometric delimitation of the thoracoabdominal compartment and expiratory flow increase technique was performed for 5 minutes with the therapist’s hands on the thorax and abdomen. Newborns were filmed before and after the maneuver and the frames were analyzed in AutoCAD® software by a blinded investigator at the time of the procedure. The largest and the smallest thoracoabdominal area were expressed in cm2 and the mean values were compared between two moments (pre and post maneuver by paired t test. Results: Twenty newborns with a mean age of 39 weeks were included. Before the maneuver, thoracoabdominal area was 56.1 cm2 during expiration and 59.7 cm2 during inspiration, and after the maneuver the value was 56.2 cm2 during expiration and 59.8 cm2 during inspiration, with no statistical difference between before and after (p = 0.97, p = 0.92, respectively. Conclusion: Results demonstrate that expiratory flow increase technique does not seem to change thoracoabdominal mobility of healthy newborns.

  13. The association of forced expiratory volume in one second and forced expiratory flow at 50% of the vital capacity, peak expiratory flow parameters, and blood eosinophil counts in exercise-induced bronchospasm in children with mild asthma.

    Science.gov (United States)

    Akar, H Haluk; Tahan, Fulya; Gungor, Hatice Eke

    2015-04-01

    Exercise-induced bronchoconstriction (EIB), which describes acute airway narrowing that occurs as a result of exercise, is associated with eosinophilic airway inflammation, bronchial hyperresponsiveness. The forced expiratory volume in one second (FEV1) is the most commonly used spirometric test in the diagnosis of EIB in exercise challenge in asthma. Other parameters such as forced expiratory flow at 50% of the vital capacity (FEF50%) and peak expiratory flow (PEF) are used less often in the diagnosis of EIB. The purpose of this study is to evaluate the association of FEV1 and FEF50%, PEF parameters, blood eosinophil counts in EIB in children with mild asthma. Sixty-seven children (male: 39, female: 28) with mild asthma were included in this study. Pulmonary functions were assessed before and at 1, 5, 10, 15, and 20 minutes after exercise. The values of spirometric FEV1, FEF50%, PEF, and blood eosinophil counts were evaluated in EIB in children with mild asthma. There was a positive correlation between FEV1 with FEF50% and PEF values (p<0.05; FEF50%, r=0.68; PEF, r=0.65). Also, a positive correlation was found between blood eosinophil counts and the values of spirometric FEV1, FEF50%, and PEF (p<0.05; FEV1, r=0.54; FEF50%, r=0.42; PEF, r=0.26). In addition to these correlations, in the exercise negative group for FEV1, the FEF50% and PEF values decreased more than the cutoff values in 3, and 2 patients, respectively. According to the presented study, eosinophil may play a major role in the severity of EIB in mild asthma. FEF50% and PEF values can decrease in response to exercise without changes in FEV1 in mild asthmatic patients.

  14. Effect of abdominal muscle training on respiratory muscle strength and forced expiratory flows in sedentary, healthy adolescents.

    Science.gov (United States)

    Rodríguez-Núñez, Iván; Navarro, Ximena; Gatica, Darwin; Manterola, Carlos

    2016-10-01

    Respiratory muscle training is the most commonly used method to revert respiratory muscle weakness; however, the effect of protocols based on non-respiratory maneuvers has not been adequately studied in the pediatric population. The objective of this study was to establish the effect of abdominal muscle training on respiratory muscle strength and forced expiratory flows in healthy adolescents. This was a quasi-experiment. The sample was made up of healthy adolescents divided into two groups: an experimental group who completed eight weeks of active abdominal muscle training, and an equivalent control group. The following indicators were measured: abdominal muscle strength, maximal inspiratory pressure, maximal expiratory pressure (MEP), peak expiratory flow, and peak cough flow, before and after protocol completion. A value of p abdominal muscle training, MEP and peak expiratory flow increased in healthy (sedentary) adolescents. Such effects were associated with intervention-induced increases in cough peak flow. Sociedad Argentina de Pediatría.

  15. Peak expiratory flow rate in healthy children aged 6-17 years

    DEFF Research Database (Denmark)

    Høst, A; Høst, A H; Ibsen, T

    1994-01-01

    Peak expiratory flow rate (PEFR) was measured in a cross-sectional study in 861 healthy Danish schoolchildren aged 6-17 years using a Mini Wright peak flowmeter. We found a strong correlation between PEFR and height, age and sex. The results were comparable with those from previous studies using...... a Wright peak flowmeter. The equation for prediction of PEFR in boys was calculated as (3.8 x height) + (10.6 x age) - 313.2 (p ... coefficient in this large sample. Among healthy children without previous asthma, earlier episodes of recurrent wheezing were reported in 8.8% and a significantly lower PEFR was found in this group....

  16. Exercise challenge in patients with asthma whose peak expiratory flow values are controlled within the green zone

    Directory of Open Access Journals (Sweden)

    Hideko Kobayashi

    1999-01-01

    Full Text Available Recent guidelines for the management of asthma recommend that peak expiratory flow (PEF should be measured to monitor the level of airflow limitation and to maintain PEF values within the green zone (80–100% of the patient's highest PEF value. Because no studies have evaluated the efficacy of PEF zone management on the basis of patients' physical activity, we studied the appearance of exercise-induced asthma (EIA using treadmill exercise challenging in asthma patients whose PEF values had been maintained in the green zone for at least 3 months. Exercise-induced asthma was induced in nine of 44 (20.5% asthma patients. The acetylcholine concentration required to cause a 20% fall in forced expiratory volume in 1 s (log PC20 was significantly lower in patients with EIA (2.39±0.21 μg/mL compared with patients without EIA (3.22±0.12 μg/mL; P <0.03. These results suggest that PEF green zone management alone does not ensure the ability to perform vigorous physical activity, especially in patients whose airway reactivity remains enhanced. Therefore, airway reactivity should be considered for asthma management.

  17. Typical patterns of expiratory flow and carbon dioxide in mechanically ventilated patients with spontaneous breathing.

    Science.gov (United States)

    Rees, S E; Larraza, S; Dey, N; Spadaro, S; Brohus, J B; Winding, R W; Volta, C A; Karbing, D S

    2017-08-01

    Incomplete expiration of tidal volume can lead to dynamic hyperinflation and auto-PEEP. Methods are available for assessing these, but are not appropriate for patients with respiratory muscle activity, as occurs in pressure support. Information may exist in expiratory flow and carbon dioxide measurements, which, when taken together, may help characterize dynamic hyperinflation. This paper postulates such patterns and investigates whether these can be seen systematically in data. Two variables are proposed summarizing the number of incomplete expirations quantified as a lack of return to zero flow in expiration (IncExp), and the end tidal CO 2 variability (varETCO 2 ), over 20 breaths. Using these variables, three patterns of ventilation are postulated: (a) few incomplete expirations (IncExp  18) and small varETCO 2 . IncExp and varETCO 2 were calculated from data describing respiratory flow and CO 2 signals in 11 patients mechanically ventilated at 5 levels of pressure support. Data analysis showed that the three patterns presented systematically in the data, with periods of IncExp  18 having significantly lower variability in end-tidal CO 2 than periods with 2 ≤ IncExp ≤ 18 (p  18 to 2 ≤ IncExp ≤ 18 results in significant, rapid, change in the variability of end-tidal CO 2 p < 0.05. This study illustrates that systematic patterns of expiratory flow and end-tidal CO 2 are present in patients in supported mechanical ventilation, and that changes between these patterns can be identified. Further studies are required to see if these patterns characterize dynamic hyperinflation. If so, then their combination may provide a useful addition to understanding the patient at the bedside.

  18. Comparison of abdominal muscle activity and peak expiratory flow between forced vital capacity and fast expiration exercise.

    Science.gov (United States)

    Ishida, Hiroshi; Suehiro, Tadanobu; Watanabe, Susumu

    2017-04-01

    [Purpose] The purpose of this investigation was to compare the activities of the abdominal muscles and peak expiratory flow between forced vital capacity and fast expiration exercise. [Subjects and Methods] Fifteen healthy male participated in this study. Peak expiratory flow and electromyographic activities of the rectus abdominis, external oblique, and internal oblique/transversus abdominis muscles were measured during forced vital capacity and fast expiration exercise and then peak amplitude and its appearance time were obtained. [Results] Peak expiratory flow values were significantly higher during fast expiration exercise than during forced vital capacity. The internal oblique/transversus abdominis muscles showed significantly higher peak amplitude during fast expiration exercise than during forced vital capacity. However, there were no significant differences between forced vital capacity and fast expiration exercise in the rectus abdominis and external oblique muscles. There was no difference in the appearance time of the peak amplitude between forced vital capacity and fast expiration exercise in any muscle. [Conclusion] Fast expiration exercise might be beneficial for increasing expiratory speed and neuromuscular activation of the internal oblique/transversus abdominis muscles compared to forced vital capacity. These findings could be considered when recommending a variation of expiratory muscle strength training as part of pulmonary rehabilitation programs.

  19. Peak expiratory flow rate (PEFR) among Nuclear Fuel Complex (NFC) employees

    International Nuclear Information System (INIS)

    Vijay Rao, J.; Venkaiah, K.; Mohan Rao, N.

    2010-01-01

    At Nuclear Fuel Complex (NFC), employees are exposed to ammonia, hydrofluoric acid, acetone, etc., which are respiratory toxicants and inhalation of these pollutants may produce irritation and obstruction in airways. Due to nature of their occupation, tradesman working in plants are having longer duration of exposure (LDE) and others, such as supervisors, scientific officers, helpers, etc., that occasionally visit plants are having shorter duration of exposure (SDE) to these pollutants. The peak expiratory flow rate (PEFR) is an index to diagnose obstruction in larger airways and this is metered with mini peak flow meter among 835 NFC employees. Using ANOVA test, PEFR value was compared according to age and smoking. The value was compared between LDE and SDE employees according to smoking and duration of employment. The multiple regression equation for prediction of PEFR was developed. Age, smokers and higher duration of LDE employees demonstrated significantly lower PEFR value. In comparison to 10 year duration, 30 and above year duration of employment, LDE employees showed a higher decline in PEFR, that is 95 L (17.6%) and in SDE employees, that is 41L (7.8%). This may be due to longer duration of employment of LD employees smoking prevention and follow up study is suggested. (author)

  20. Can Peak Expiratory Flow Measurements Differentiate Chronic Obstructive Pulmonary Disease from Congestive Heart Failure?

    Directory of Open Access Journals (Sweden)

    John E. Gough

    2012-01-01

    Full Text Available Dyspneic patients are commonly encountered by Emergency Medical Service (EMS. Frequent causes include Chronic Obstructive Pulmonary Disease (COPD and Congestive Heart Failure (CHF. Measurement of peak expiratory flow rate (PEFR has been proposed to help differentiate COPD from CHF. This prospective, cohort, pilot study was conducted to determine if PEFR in patients with an exacerbation of COPD were significantly different than CHF. Included were patients presenting with dyspnea plus a history of COPD and/or CHF. A PEFR was measured, values were compared to predicted average, and a percentage was calculated. Twenty-one patients were enrolled. Six had a diagnosis of COPD, 12 CHF; 3 had other diagnoses. Mean percentage of predicted PEFR with COPD was 26.36%, CHF 48.9% (=0.04. Patients presenting with acute COPD had significantly lower percentage of predicted PEFR than those with CHF. These results suggest that PEFR may be useful in differentiating COPD from CHF. This study should be expanded to the prehospital setting with a larger number of subjects.

  1. First characterization of the expiratory flow increase technique: method development and results analysis

    International Nuclear Information System (INIS)

    Maréchal, L; Barthod, C; Jeulin, J C

    2009-01-01

    This study provides an important contribution to the definition of the expiratory flow increase technique (EFIT). So far, no measuring means were suited to assess the manual EFIT performed on infants. The proposed method aims at objectively defining the EFIT based on the quantification of pertinent cognitive parameters used by physiotherapists when practicing. We designed and realized customized instrumented gloves endowed with pressure and displacement sensors, and the associated electronics and software. This new system is specific to the manoeuvre, to the user and innocuous for the patient. Data were collected and analysed on infants with bronchiolitis managed by an expert physiotherapist. The analysis presented is realized on a group of seven subjects (mean age: 6.1 months, SD: 1.1; mean chest circumference: 44.8 cm, SD: 1.9). The results are consistent with the physiotherapist's tactility. In spite of inevitable variability due to measurements on infants, repeatable quantitative data could be reported regarding the manoeuvre characteristics: the magnitudes of displacements do not exceed 10 mm on both hands; the movement of the thoracic hand is more vertical than the movement of the abdominal hand; the maximum applied pressure with the thoracic hand is about twice higher than with the abdominal hand; the thrust of the manual compression lasts (590 ± 62) ms. Inter-operators measurements are in progress in order to generalize these results

  2. Can Preoperative Peak Expiratory Flow Predict Postoperative Pulmonary Complications in Lung Cancer Patients Undergoing Lobectomy?

    Directory of Open Access Journals (Sweden)

    Kun ZHOU

    2017-09-01

    Full Text Available Background and objective Postoperative pulmonary complications (PPCs, especially postoperative pneumonia (POP, directly affect the rapid recovery of lung cancer patients after surgery. Peak expiratory flow (PEF can reflect airway patency and cough efficiency. Moreover, cough impairment may lead to accumulation of pulmonary secretions which can increase the risk of PPCs. The aim of this study is to investigate the effect of preoperative PEF on PPCs in patients with lung cancer. Methods Retrospective research was conducted on 433 lung cancer patients who underwent lobectomy at the West China Hospital of Sichuan University from January 2014 to December 2015. The associations between preoperative PEF and PPCs were analyzed based on patients’ basic characteristics and clinical data in hospital. Results Preoperative PEF value in PPCs group (280.93±88.99 L/min was significantly lower than that in non-PPCs group (358.38±93.69 L/min (P320 L/min group (9.4%(P<0.001. Conclusion Preoperative PEF and PPCs are correlated, and PEF may be used as a predictor of PPCs.

  3. The effects of smokeless cookstoves on peak expiratory flow rates in rural Honduras.

    Science.gov (United States)

    Rennert, W P; Porras Blanco, R M; Muniz, G B

    2015-09-01

    The use of biomass fuel for cooking in traditional cookstove designs negatively affects respiratory health of communities in developing countries. Indoor pollution affects particularly women and children, who are participating in food preparation. The effects of smokeless cookstove designs on indoor pollution are well documented, but few studies exist to assess the effects of improved stove designs on the respiratory health of community members. This study uses peak expiratory flow rate (PEFR) measurements in a before-and-after format to assess respiratory function of inhabitants of all 30 houses of Buenas Noches in central Honduras. PEFRs are measured before and 6 months after the installation of Justa stoves in people's homes. Health behaviors, respiratory symptoms and fire wood use are evaluated in a door-to-door survey format. A total of 137 eligible women and children between 6 and 14 years participated in the study. PEFR improved by 9.9-18.5% (P < 0.001) depending on the participants' exposure to indoor pollution. Health complaints like cough and behaviors like clinic visits did not change with the introduction of smokeless cookstove technology. Smokeless stoves improve respiratory health in an environment of high levels of indoor pollution. © The Author 2014. Published by Oxford University Press on behalf of Faculty of Public Health. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  4. Expiratory flow rate, breath hold and anatomic dead space influence electronic nose ability to detect lung cancer.

    Science.gov (United States)

    Bikov, Andras; Hernadi, Marton; Korosi, Beata Zita; Kunos, Laszlo; Zsamboki, Gabriella; Sutto, Zoltan; Tarnoki, Adam Domonkos; Tarnoki, David Laszlo; Losonczy, Gyorgy; Horvath, Ildiko

    2014-12-16

    Electronic noses are composites of nanosensor arrays. Numerous studies showed their potential to detect lung cancer from breath samples by analysing exhaled volatile compound pattern ("breathprint"). Expiratory flow rate, breath hold and inclusion of anatomic dead space may influence the exhaled levels of some volatile compounds; however it has not been fully addressed how these factors affect electronic nose data. Therefore, the aim of the study was to investigate these effects. 37 healthy subjects (44 ± 14 years) and 27 patients with lung cancer (60 ± 10 years) participated in the study. After deep inhalation through a volatile organic compound filter, subjects exhaled at two different flow rates (50 ml/sec and 75 ml/sec) into Teflon-coated bags. The effect of breath hold was analysed after 10 seconds of deep inhalation. We also studied the effect of anatomic dead space by excluding this fraction and comparing alveolar air to mixed (alveolar + anatomic dead space) air samples. Exhaled air samples were processed with Cyranose 320 electronic nose. Expiratory flow rate, breath hold and the inclusion of anatomic dead space significantly altered "breathprints" in healthy individuals (p 0.05). These factors also influenced the discrimination ability of the electronic nose to detect lung cancer significantly. We have shown that expiratory flow, breath hold and dead space influence exhaled volatile compound pattern assessed with electronic nose. These findings suggest critical methodological recommendations to standardise sample collections for electronic nose measurements.

  5. A comparison of peak expiratory flow measured from forced vital capacity and peak flow meter manoeuvres in healthy volunteers

    Directory of Open Access Journals (Sweden)

    Agarwal Dipti

    2007-01-01

    Full Text Available Background: Spirometry measures the mechanical function of lungs, chest wall and respiratory muscles by assessing the total volume of air exhaled from total lung capacity to residual volume. Spirometry and peak flow measurements have usually been carried out on separate equipments using different expiratory maneuvers. Aims: The present study was carried out to determine whether there is a significant difference between peak expiratory flow (PEF derived from a short sharp exhalation (PEF maneuver and that derived from a full forced vital capacity (FVC maneuver in healthy volunteers. Settings: A medical college and tertiary level hospital. Materials and Methods: The present study was carried out during the period from January 2006 to July 2006. The study included 80 healthy volunteers with no coexisting illnesses, who were in the 15-45 years age group and belonging to either sex. They were asked to perform two sets of PEF and FVC maneuvers using the same turbine spirometer; the order was randomly assigned.th Statistical Analysis: The difference between PEF obtained from a peak flow maneuver (PEFPF and that obtained from a forced vital capacity maneuver (PEFVC in healthy volunteers was analyzed separately for males and females, as well as for both groups combined, and statistical significance of its correlations with study data parameters was analyzed.th Results: The difference between PEF obtained from a peak flow maneuver (PEFPF and that obtained from a forced vital capacity maneuver (PEFVC was statistically significant ( P < 0.001 in males and in females separately and also for both groups combined. PEFPF (517.25 ± 83.22 liters/min was significantly greater than PEFVC (511.09 ± 83.54 liters/min, as found on combined group mean analysis. However, the difference was small (6.16 + 7.09 liters/min. Conclusions: FVC maneuver can be used over spirometers to detect the PEF; and on follow-up subsequently, the same maneuver should be used to derive PEF

  6. Fluctuation Analysis of Peak Expiratory Flow and Its Association with Treatment Failure in Asthma.

    Science.gov (United States)

    Kaminsky, David A; Wang, Lucy L; Bates, Jason H T; Thamrin, Cindy; Shade, David M; Dixon, Anne E; Wise, Robert A; Peters, Stephen; Irvin, Charles G

    2017-04-15

    Temporal fluctuations have been demonstrated in lung function and asthma control, but the effect of controller therapy on these fluctuations is unknown. To determine if fluctuations in peak expiratory flow (PEF) are predictive of subsequent treatment failure and may be modified by controller therapy. We applied detrended fluctuation analysis to once-daily PEF data from 493 participants in the LOCCS (Leukotriene Modifier Corticosteroid or Corticosteroid-Salmeterol) trial of the American Lung Association Airways Clinical Research Centers. We evaluated the coefficient of variation of PEF (CVpef) and the scaling exponent α, reflecting self-similarity of PEF, in relation to treatment failure from the run-in period of open-label inhaled fluticasone, and the treatment periods for subjects randomized to (1) continued twice daily fluticasone (F), (2) once daily fluticasone plus salmeterol (F + S), or (3) once daily oral montelukast (M). The CVpef was higher in those with treatment failure in the F and F + S groups in the run-in phase, and all three groups in the treatment phase. α was similar between those with and without treatment failure in all three groups during the run-in phase but was higher among those with treatment failure in the F and F + S groups during the treatment phase. Participants in all three groups showed variable patterns of change in α leading up to treatment failure. We conclude that increased temporal self-similarity (α) of more variable lung function (CVpef) is associated with treatment failure, but the pattern of change in self-similarity leading up to treatment failure is variable across individuals.

  7. Difficulty in obtaining peak expiratory flow measurements in children with acute asthma.

    Science.gov (United States)

    Gorelick, Marc H; Stevens, Molly W; Schultz, Theresa; Scribano, Philip V

    2004-01-01

    To determine the frequency with which children >or=6 years with acute asthma can perform peak expiratory flow rate measurements (PEFR) in an emergency department (ED). Data were obtained from a prospective cohort study of children with acute asthma. All children (age 2-18 years old) treated in an urban pediatric ED for an acute exacerbation during randomly selected days over a 12-month period were prospectively evaluated. According to treatment protocols, PEFR was to be measured in all children age 6 years and older before therapy and after each treatment with inhaled bronchodilators. Registered respiratory therapists obtained PEFR and evaluated whether patients were able to perform the maneuver adequately. Four hundred and fifty-six children, 6 to 18 years old (median 10 years), were enrolled; 291 (64%) had PEFR measured at least once. Of those in whom PEFR was attempted at least once, only 190 (65%) were able to perform adequately. At the start of therapy, 54% (142/262) were able to perform PEFR. Of the 120 who were unable to perform initially, 76 had another attempt at the end of the ED treatment, and 55 (72%) were still unable to perform. A total of 149 patients had attempts at PEFR both at the start and end of treatment, of these, only 71 (48%) provided valid information on both attempts. Patients unable to perform PEFR were younger (mean +/- SD = 8.7 +/- 2.8 years) than those who were able to perform successfully (11.2 +/- 3.2 years) and those with no attempts (10.0 +/- 3.4 years). Children admitted to the hospital were more likely to be unable to perform PEFR (58/126 = 46%) than those discharged from the ED (43/330 = 13%, P < 0.0001). Adequate PEFR measurements are difficult to obtain in children with acute asthma. Treatment and research protocols cannot rely exclusively on PEFR for evaluation of severity.

  8. Daily changes of peak expiratory flow and respiratory symptom occurrence around a soy processing factory

    Directory of Open Access Journals (Sweden)

    Dick Heederik

    2014-04-01

    Full Text Available Objectives. To evaluate sensitization and acute respiratory health effects in inhabitants living in the vicinity of a factory producing soy oil. Methods. Two panels of potential responders were created on the basis of a response to a short screening questionnaire sent to random samples of 1,000 exposed and 1,000 non-exposed individuals living around the factory and a control area. Individuals responding to the questionnaire were invited for a medical evaluation, including a respiratory symptom questionnaire and skin prick testing, for a panel of common allergens and a soy allergen extract. This resulted in 53 atopic and/or asthmatic inhabitants from the area surrounding the factory and 30 comparable control subjects. In these subjects, morning and evening Peak Expiratory Flow (PEF, respiratory symptoms and medication use were recorded daily during a 10-week period in the autumn. At the same time, soy allergen and endotoxin concentrations were determined in airborne dust in the exposed and the control area. The wind direction relative to the location of a subjects’ house and the factory was used to determine whether an individual was exposed on a particular day. Results. Only few of the atopic subjects were sensitized to soy. PEF showed a decrease, respiratory symptoms and bronchodilator use, an increase among soy sensitized subjects after having been downwind from the factory. Airborne soy allergen was found more frequently in the area surrounding the factory and levels were higher than in the control area. Highest levels were found on the factory premises. Only a weak association was found with wind direction. Airborne endotoxin concentrations did not show a consistent pattern with distance, but levels were clearly higher on the factory premises. Conclusion. Sensitization to soy allergen was not increased among the population sample living in the vicinity of the factory. Soy sensitized individuals living in the surroundings of the factory

  9. Daily changes of peak expiratory flow and respiratory symptom occurrence around a soy processing factory

    Directory of Open Access Journals (Sweden)

    Dick Heederik

    2014-03-01

    Full Text Available Objectives. To evaluate sensitization and acute respiratory health effects in inhabitants living in the vicinity of a factory producing soy oil. Methods. Two panels of potential responders were created on the basis of a response to a short screening questionnaire sent to random samples of 1,000 exposed and 1,000 non-exposed individuals living around the factory and a control area. Individuals responding to the questionnaire were invited for a medical evaluation, including a respiratory symptom questionnaire and skin prick testing, for a panel of common allergens and a soy allergen extract. This resulted in 53 atopic and/or asthmatic inhabitants from the area surrounding the factory and 30 comparable control subjects. In these subjects, morning and evening Peak Expiratory Flow (PEF, respiratory symptoms and medication use were recorded daily during a 10-week period in the autumn. At the same time, soy allergen and endotoxin concentrations were determined in airborne dust in the exposed and the control area. The wind direction relative to the location of a subjects’ house and the factory was used to determine whether an individual was exposed on a particular day. Results. Only few of the atopic subjects were sensitized to soy. PEF showed a decrease, respiratory symptoms and bronchodilator use, an increase among soy sensitized subjects after having been downwind from the factory. Airborne soy allergen was found more frequently in the area surrounding the factory and levels were higher than in the control area. Highest levels were found on the factory premises. Only a weak association was found with wind direction. Airborne endotoxin concentrations did not show a consistent pattern with distance, but levels were clearly higher on the factory premises. Conclusion. Sensitization to soy allergen was not increased among the population sample living in the vicinity of the factory. Soy sensitized individuals living in the surroundings of the factory

  10. Comparison of peak expiratory flow rate and lipid profile in asymptomatic smokers and non-smokers

    International Nuclear Information System (INIS)

    Fatima, F.; Abbasi, M.A.; Jadoon, J.; Sohail, M.; Shah, J.; Afridi, U.; Noor, M.M.

    2015-01-01

    Tobacco is the major risk factor for chronic obstructive airway disease (COAD), other pulmonary diseases, cancer, cardiovascular and cerebrovascular diseases. The objective of study was to determine the mean Peak Expiratory Flow Rate (PEFR) and serum lipid profile in apparently healthy male smokers and non-smokers. Methods: This cross-sectional study was conducted in Ayub Teaching Hospital, Abbottabad from 15th December, 2009 to 15th June, 2010. Apparently healthy smokers and non-smokers from population coming to Hospital as attendants of the patients or as employees of the hospital were inducted in the study. PEFR and lipid profile of all the subjects was accessed. Results: There were total of 300 male subjects, 150 smokers and 150 non-smokers. The mean age of study subjects was 26.60 ± 5.5 years. The mean PEFR of smokers was 450.62l/min and that of non-smokers was 494.81 L/min, the difference being statistically significant (p-value <0.05).The mean total cholesterol of smokers is 5.30 ± 0.86 mmol/l and it was 3.84 ± 0.54 mmol/l in non-smokers. Mean serum Triacyl Glycerols (TAGs) and Low Density Lipoproteins (LDL) cholesterol of smokers was 2.04 ± 0.38 and 3.5 ± 0.83 mmol/l whereas it was 1.44 ± 0.52 and 2.02 ± 0.66 mmol/l in non-smokers. Mean High Density Lipo-protein (HDL) of smokers was 0.86 ± 0.30 mmol/l and of non-smokers is 1.20 ± 0.41 mmo/l. There was statistically significant difference between serum lipid profile of smokers and non-smokers (p<0.05). the mean serum Total Cholesterol (TC), TAGs and LDL were significantly higher in smokers as compared to non-smokers. However HDL was significantly lower in smokers in comparison to non-smokers. Conclusion: There was statistically significant difference between PEFR of smokers and non-smokers. Higher and significant mean values of TC, TAG and LDL-C was observed in smokers as compared to non-smokers. (author)

  11. Role of bronchodilation and pattern of breathing in increasing tidal expiratory flow with progressive induced hypercapnia in chronic obstructive pulmonary disease.

    Science.gov (United States)

    Finucane, Kevin E; Singh, Bhajan

    2018-01-01

    Hypercapnia (HC) in vitro relaxes airway smooth muscle; in vivo, it increases respiratory effort, tidal expiratory flows (V̇ exp ), and, by decreasing inspiratory duration (Ti), increases elastic recoil pressure (Pel) via lung viscoelasticity; however, its effect on airway resistance is uncertain. We examined the contributions of bronchodilation, Ti, and expiratory effort to increasing V̇ exp with progressive HC in 10 subjects with chronic obstructive pulmonary disease (COPD): mean forced expiratory volume in 1 s (FEV 1 ) 53% predicted. Lung volumes (Vl), V̇ exp , esophageal pressure (Pes), Ti, and end-tidal Pco 2 ([Formula: see text]) were measured during six tidal breaths followed by an inspiratory capacity (IC), breathing air, and at three levels of HC. V̇ exp and V̇ with submaximal forced vital capacities breathing air (V̇ sFVC ) were compared. Pulmonary resistance ( Rl) was measured from the Pes-V̇ relationship. V̇ exp and Pes at end-expiratory lung volume (EELV) + 0.3 tidal volume [V̇ (0.3Vt) and Pes (0.3Vt) , respectively], Ti, and Rl correlated with [Formula: see text] ( P tidal expiratory flows by inducing bronchodilation and via an increased rate of inspiration and lung viscoelasticity, a probable increase in lung elastic recoil pressure, both changes increasing expiratory flows, promoting lung emptying and a stable end-expiratory volume. Bronchodilation with HC occurred despite optimal standard bronchodilator therapy, suggesting that in COPD further bronchodilation is possible.

  12. Functional electrical stimulation to the abdominal wall muscles synchronized with the expiratory flow does not induce muscle fatigue.

    Science.gov (United States)

    Okuno, Yukako; Takahashi, Ryoichi; Sewa, Yoko; Ohse, Hirotaka; Imura, Shigeyuki; Tomita, Kazuhide

    2017-03-01

    [Purpose] Continuous electrical stimulation of abdominal wall muscles is known to induce mild muscle fatigue. However, it is not clear whether this is also true for functional electrical stimulation delivered only during the expiratory phase of breathing. This study aimed to examine whether or not intermittent electrical stimulation delivered to abdominal wall muscles induces muscle fatigue. [Subjects and Methods] The subjects were nine healthy adults. Abdominal electrical stimulation was applied for 1.5 seconds from the start of expiration and then turned off during inspiration. The electrodes were attached to both sides of the abdomen at the lower margin of the 12th rib. Abdominal electrical stimulation was delivered for 15 minutes with the subject in a seated position. Expiratory flow was measured during stimulus. Trunk flexor torque and electromyography activity were measured to evaluate abdominal muscle fatigue. [Results] The mean stimulation on/off ratio was 1:2.3. The declining rate of abdominal muscle torque was 61.1 ± 19.1% before stimulus and 56.5 ± 20.9% after stimulus, not significantly different. The declining rate of mean power frequency was 47.8 ± 11.7% before stimulus and 47.9 ± 10.2% after stimulus, not significantly different. [Conclusion] It was found that intermittent electrical stimulation to abdominal muscles synchronized with the expiratory would not induce muscle fatigue.

  13. Assessment and monitoring of flow limitation and other parameters from flow/volume loops.

    Science.gov (United States)

    Dueck, R

    2000-01-01

    Flow/volume (F/V) spirometry is routinely used for assessing the type and severity of lung disease. Forced vital capacity (FVC) and timed vital capacity (FEV1) provide the best estimates of airflow obstruction in patients with asthma, chronic obstructive pulmonary disease (COPD) and emphysema. Computerized spirometers are now available for early home recognition of asthma exacerbation in high risk patients with severe persistent disease, and for recognition of either infection or rejection in lung transplant patients. Patients with severe COPD may exhibit expiratory flow limitation (EFL) on tidal volume (VT) expiratory F/V (VTF/V) curves, either with or without applying negative expiratory pressure (NEP). EFL results in dynamic hyperinflation and persistently raised alveolar pressure or intrinsic PEEP (PEEPi). Hyperinflation and raised PEEPi greatly enhance dyspnea with exertion through the added work of the threshold load needed to overcome raised pleural pressure. Esophageal (pleural) pressure monitoring may be added to VTF/V loops for assessing the severity of PEEPi: 1) to optimize assisted ventilation by mask or via endotracheal tube with high inspiratory flow rates to lower I:E ratio, and 2) to assess the efficacy of either pressure support ventilation (PSV) or low level extrinsic PEEP in reducing the threshold load of PEEPi. Intraoperative tidal volume F/V loops can also be used to document the efficacy of emphysema lung volume reduction surgery (LVRS) via disappearance of EFL. Finally, the mechanism of ventilatory constraint can be identified with the use of exercise tidal volume F/V loops referenced to maximum F/V loops and static lung volumes. Patients with severe COPD show inspiratory F/V loops approaching 95% of total lung capacity, and flow limitation over the entire expiratory F/V curve during light levels of exercise. Surprisingly, patients with a history of congestive heart failure may lower lung volume towards residual volume during exercise

  14. Paired inspiratory/expiratory volumetric CT and deformable image registration for quantitative and qualitative evaluation of airflow limitation in smokers with or without copd.

    Science.gov (United States)

    Nishio, Mizuho; Matsumoto, Sumiaki; Tsubakimoto, Maho; Nishii, Tatsuya; Koyama, Hisanobu; Ohno, Yoshiharu; Sugimura, Kazuro

    2015-03-01

    To evaluate paired inspiratory/expiratory computed tomography (CT; iCT/eCT) and deformable image registration for quantitative and qualitative assessment of airflow limitation in smokers. Paired iCT/eCT images acquired from 35 smokers (30 men and 5 women) were coregistered and subtraction images (air trapping CT images [aCT]) generated. To evaluate emphysema quantitatively, the percentage of low-attenuation volume (LAV%) on iCT was calculated at -950 HU, as were mean and kurtosis on aCT for quantitative assessment of air trapping. Parametric response maps of emphysema (PRMe) and of functional small airways disease (PRMs) were also obtained. For qualitative evaluation of emphysema, low-attenuation areas on iCT were scored by consensus of two radiologists using Goddard classification. To assess air trapping qualitatively, the degree of air trapping on aCT was scored. For each quantitative and qualitative index, the Spearman rank correlation coefficient for forced expiratory flow in 1 second was calculated, and differences in correlation coefficients were statistically tested. The correlation coefficients for the indices were as follows: mean on aCT, 0.800; kurtosis on aCT, -0.726; LAV%, -0.472; PRMe, -0.570; PRMs, -0.565; addition of PRMe and PRMs, -0.653; emphysema score, -0.502; air trapping score, -0.793. The indices showing significant differences were as follows: mean on aCT and addition of PRMe and PRMs (P = 1.43 × 10(-8)); air trapping score and emphysema score (P = .0169). Air trapping images yielded more accurate quantitative and qualitative evaluation of airflow limitation than did LAV%, PRMe, PRMs, and Goddard classification. Copyright © 2015 AUR. Published by Elsevier Inc. All rights reserved.

  15. Paired maximum inspiratory and expiratory plain chest radiographs for assessment of airflow limitation in chronic obstructive pulmonary disease

    Energy Technology Data Exchange (ETDEWEB)

    Kinoshita, Takashi, E-mail: tkino@med.kurume-u.ac.jp [Division of Respirology, Neurology, and Rheumatology, Department of Medicine, Kurume University School of Medicine, Kurume (Japan); Kawayama, Tomotaka, E-mail: kawayama_tomotaka@med.kurume-u.ac.jp [Division of Respirology, Neurology, and Rheumatology, Department of Medicine, Kurume University School of Medicine, Kurume (Japan); Imamura, Youhei, E-mail: mamura_youhei@med.kurume-u.ac.jp [Division of Respirology, Neurology, and Rheumatology, Department of Medicine, Kurume University School of Medicine, Kurume (Japan); Sakazaki, Yuki, E-mail: sakazaki@med.kurume-u.ac.jp [Division of Respirology, Neurology, and Rheumatology, Department of Medicine, Kurume University School of Medicine, Kurume (Japan); Hirai, Ryo, E-mail: hirai_ryou@kurume-u.ac.jp [Division of Respirology, Neurology, and Rheumatology, Department of Medicine, Kurume University School of Medicine, Kurume (Japan); Ishii, Hidenobu, E-mail: shii_hidenobu@med.kurume-u.ac.jp [Division of Respirology, Neurology, and Rheumatology, Department of Medicine, Kurume University School of Medicine, Kurume (Japan); Suetomo, Masashi, E-mail: jin_t_f_c@yahoo.co.jp [Division of Respirology, Neurology, and Rheumatology, Department of Medicine, Kurume University School of Medicine, Kurume (Japan); Matsunaga, Kazuko, E-mail: kmatsunaga@kouhoukai.or.jp [Division of Respirology, Neurology, and Rheumatology, Department of Medicine, Kurume University School of Medicine, Kurume (Japan); Azuma, Koichi, E-mail: azuma@med.kurume-u.ac.jp [Division of Respirology, Neurology, and Rheumatology, Department of Medicine, Kurume University School of Medicine, Kurume (Japan); Fujimoto, Kiminori, E-mail: kimichan@med.kurume-u.ac.jp [Department of Radiology, Kurume University School of Medicine, Kurume (Japan); Hoshino, Tomoaki, E-mail: hoshino@med.kurume-u.ac.jp [Division of Respirology, Neurology, and Rheumatology, Department of Medicine, Kurume University School of Medicine, Kurume (Japan)

    2015-04-15

    Highlights: •It is often to use computed tomography (CT) scan for diagnosis of chronic obstructive pulmonary disease. •CT scan is more expensive and higher. •A plane chest radiography more simple and cheap. Moreover, it is useful as detection of pulmonary emphysema, but not airflow limitation. •Our study demonstrated that the maximum inspiratory and expiratory plane chest radiography technique could detect severe airflow limitations. •We believe that the technique is helpful to diagnose the patients with chronic obstructive pulmonary disease. -- Abstract: Background: The usefulness of paired maximum inspiratory and expiratory (I/E) plain chest radiography (pCR) for diagnosis of chronic obstructive pulmonary disease (COPD) is still unclear. Objectives: We examined whether measurement of the I/E ratio using paired I/E pCR could be used for detection of airflow limitation in patients with COPD. Methods: Eighty patients with COPD (GOLD stage I = 23, stage II = 32, stage III = 15, stage IV = 10) and 34 control subjects were enrolled. The I/E ratios of frontal and lateral lung areas, and lung distance between the apex and base on pCR views were analyzed quantitatively. Pulmonary function parameters were measured at the same time. Results: The I/E ratios for the frontal lung area (1.25 ± 0.01), the lateral lung area (1.29 ± 0.01), and the lung distance (1.18 ± 0.01) were significantly (p < 0.05) reduced in COPD patients compared with controls (1.31 ± 0.02 and 1.38 ± 0.02, and 1.22 ± 0.01, respectively). The I/E ratios in frontal and lateral areas, and lung distance were significantly (p < 0.05) reduced in severe (GOLD stage III) and very severe (GOLD stage IV) COPD as compared to control subjects, although the I/E ratios did not differ significantly between severe and very severe COPD. Moreover, the I/E ratios were significantly correlated with pulmonary function parameters. Conclusions: Measurement of I/E ratios on paired I/E pCR is simple and

  16. Acu-TENS and Postexercise Expiratory Flow Volume in Healthy Subjects

    Directory of Open Access Journals (Sweden)

    Shirley P. C. Ngai

    2011-01-01

    Full Text Available Transcutaneous Electrical Nerve Stimulation over acupoints (Acu-TENS facilitates recovery of resting heart rate after treadmill exercise in healthy subjects. Its effect on postexercise respiratory indices has not been reported. This study investigates the effect of Acu-TENS on forced expiratory volume in 1 second (FEV1 and forced vital capacity (FVC in healthy subjects after a submaximal exercise. Eleven male subjects were invited to the laboratory twice, two weeks apart, to receive in random order either Acu-TENS or Placebo-TENS (no electrical output from the TENS unit over bilateral Lieque (LU7 and Dingchuan (EX-B1 for 45 minutes, before undergoing exercise following the Bruce protocol. Exercise duration, rate of perceived exertion (RPE, and peak heart rate (PHR were recorded. Between-group FEV1 and FVC, before, immediately after, at 15, 30, and 45minutes postexercise, were compared. While no between-group differences in PHR, RPE, and FVC were found, Acu-TENS was associated with a longer exercise duration (0.9 min (P=.026 and a higher percentage increase in FEV1 at 15 and 45 minutes postexercise (3.3 ± 3.7% (P=.013 and 5.1 ± 7.5% (P=.047, resp. compared to Placebo-TENS. We concluded that Acu-TENS was associated with a higher postexercise FEV1 and a prolongation of submaximal exercise.

  17. Effects of positive end-expiratory pressure and body position on pulmonary blood flow redistribution in mechanically ventilated normal pigs.

    Science.gov (United States)

    Richard, Jean-Christophe; Decailliot, Francois; Janier, Marc; Annat, Guy; Guérin, Claude

    2002-09-01

    To assess the respective effects of position and positive end-expiratory pressure (PEEP) on the distribution of regional pulmonary blood flow (PBF). Prospective randomized animal study. Animal research facility in a university hospital. Normal pigs that were tracheostomized, anesthetized, and mechanically ventilated. PBF was measured in seven pigs in the supine position (SP) and the prone position (PP) at both zero end-expiratory pressure (ZEEP) and 10 cm H(2)O of PEEP. The regional PBF was assessed by the radioactive microsphere method. The lungs from each pig were sliced into 90 samples. The heterogeneity of PBF was estimated from its coefficient of variation. The lung samples had a mean (+/- SD) weight of 1.60 +/- 0.39 g. Changing position from SP to PP at ZEEP redistributed PBF toward the anterior, superior, and peripheral regions and did not significantly reduce the coefficient of variation for regional PBF (reduction, 44.7 +/- 7% to 42.2 +/- 8%). Changing from the SP to PP position at PEEP induced a similar, but more marked, redistribution of PBF and a significant reduction in the coefficient of variation from 53 +/- 13% to 30.4 +/- 7% (p < 0.001). In the SP, PEEP redistributed PBF toward the posterior, inferior, and central regions without changing the heterogeneity of PBF. In the PP, PEEP had little effect on the PBF redistribution but significantly reduced the coefficient of variation of PBF from 42.2 +/- 8% to 30.4 +/- 7% (p < 0.05). Pigs in the PP had altered gravitational dependence of PBF compared to that observed when pigs were in the SP. This effect was enhanced by using a PEEP of 10 cm H(2)O.

  18. Distribution of peak expiratory flow variability by age, gender and smoking habits in a random population sample aged 20-70 yrs

    NARCIS (Netherlands)

    Boezen, H M; Schouten, J. P.; Postma, D S; Rijcken, B

    1994-01-01

    Peak expiratory flow (PEF) variability can be considered as an index of bronchial lability. Population studies on PEF variability are few. The purpose of the current paper is to describe the distribution of PEF variability in a random population sample of adults with a wide age range (20-70 yrs),

  19. Inadequate peak expiratory flow meter characteristics detected by a computerised explosive decompression device

    DEFF Research Database (Denmark)

    Miller, M.R.; Atkins, P.R.; Pedersen, O.F.

    2003-01-01

    Methods: The dynamic response of mini-Wright (MW), Vitalograph (V), TruZone (TZ), MultiSpiro (MS) and pneumotachograph (PT) flow meters was tested by delivering two differently shaped flow-time profiles from a computer controlled explosive decompression device fitted with a fast response solenoid.......1) and 257 (39.2), respectively, and at ≈200 l/min they were 51 (23.9) and 1 (0.5). All the meters met ATS accuracy requirements when tested with their waveforms. Conclusions: An improved method for testing the dynamic response of flow meters detects marked overshoot (underdamping) of TZ and MS responses...

  20. Comparative evaluation of ventilatory function through pre and postoperative peak expiratory flow in patients submitted to elective upper abdominal surgery.

    Science.gov (United States)

    Scheeren, Caio Fernando Cavanus; Gonçalves, José Júlio Saraiva

    2016-01-01

    to evaluate the ventilatory function by Peak Expiratory Flow (PEF) in the immediate pre and postoperative periods of patients undergoing elective surgical procedures in the upper abdomen. we conducted a prospective cohort study including 47 patients admitted to the Hospital Regional de Mato Grosso do Sul from July to December 2014, who underwent elective surgeries of the upper abdomen, and submiited to spirometric evaluation and measurement of PEF immediately before and after surgery. of the 47 patients, 22 (46.8%) were male and 25 (53.20%) female. The mean preoperative PEF was 412.1±91.7, and postoperative, 331.0±87.8, indicating significant differences between the two variables. Men had higher PEF values than women, both in the pre and postoperative periods. There was a reasonable inverse correlation between age and decreased PEF. Both situations showed statistical significance (pvalores de PFE do que o feminino, tanto no pré-cirúrgico quanto no pós-cirúrgico. Observou-se razoável correlação inversamente proporcional entre as variáveis idade e diminuição do PFE. Ambas as situações mostraram significância estatística (pvalores de PFE tanto no pré como no pós-operatório. O grupo composto por portadores de co-morbidades (HAS e/ou DM) apresentou menores valores de PFE tanto no pré como no pós-operatório (p=0,005). Em ambos os grupos, o pós-operatório determinou uma diminuição significativa do PFE (p<0,001). O tipo de cirurgia realizada e o tipo de anestesia não mostraram diferenças significantes em relação ao PFE. as variáveis mais implicadas na diminuição da função ventilatória, avaliadas através da PFE, foram: idade avançada, tabagismo e presença de comorbidades.

  1. Peak expiratory flow rate in healthy rural school going children (5-16 years) of bellur region for construction of nomogram.

    Science.gov (United States)

    Cb, Manjunath; Sc, Kotinatot; Babu, Manjunatha

    2013-12-01

    Peak Expiratory Flow Rate (PEFR) recording is an essential measure in the management and evaluation of asthmatic children.It is helpful in monitoring disease progression and response to treatment. The PEFR can be measured by a simple instrument-peak expiratory flow meter. To construct nomogram of PEFR in healthy rural school going children from Mandya district of Karnataka state, India and to use these nomograms for comparison with that of children with obstructive lung diseases for this region. The study was conducted on Healthy rural school going children, both boys and girls between the age group of 5-16 years. For the determination of PEFR we used Mini Wright Peak Flow Meter. At three time measurement, the highest value of PEFR was recorded. Formula for prediction of PEFR was estimated by linear regression analysis after the correlation of PEFR with age and height for both boys and girls. PEFR was measured in 1028 children aged 5 to 16 years by using Wright's mini peak flow meter. Prediction equations were derived for PEFR with height in boys and girls. Normograms were plotted based on the observed values of PEFR in the study population. Significant linear correlation was seen of PEFR with height in boys (paffected by regional, environmental and anthropometric factors. Hence, it is necessary to have regional reference values for children. Among different factors affecting PEFR, height correlates better with PEFR than weight and sex. Hence nomograms constructed can be used for this region.

  2. An asthma patient with steroid-resistant decrease in peak expiratory flow after the Great East Japan earthquake showing spontaneous recovery after 1 month.

    Science.gov (United States)

    Yanagimoto, Shintaro; Haida, Michiko; Suko, Matsunobu

    2012-01-01

    People living in Japan were affected in various ways after the Great East Japan earthquake of March 11, 2011. A 52-year-old female asthma patient not directly affected by the disaster experienced a decrease in peak expiratory flow (PEF) immediately after the earthquake. Despite increasing the inhaled and oral corticosteroid doses, her PEF did not recover. One month later, her PEF level abruptly returned to normal with minimal medications, which were previously ineffective, and the asthma-related symptoms vanished. The stabilization of her state of mind and actual social state seemed to be a part of the reason for the patient's recovery.

  3. TO FIND OUT THE EFFECT OF VARIOUS BODY POSITIONS ON PEAK EXPIRATORY FLOW RATE (PEFR IN COPD PATIENTS

    Directory of Open Access Journals (Sweden)

    Meghan Metha

    2016-06-01

    Full Text Available Background: COPD is the second most common lung disorder. Respiratory mechanics of COPD is altered. Lung volumes & biomechanical changes lead to weak & ineffective expiratory maneuvers. Methods: 40 COPD subjects above the age of 45years were selected through purposive sampling. The subjects were placed in seven different positions namely Standing, Chair sitting, Long sitting, Semi fowler’s position, Supine, Side lying, Head down. Following this the subject performed three tests of PEFR with intermittent rest period as preferred by the subject between each trial. Results: PEFR achieved by subjects with COPD were significantly affected by body position. Standing (161.82 led to results which were significantly higher than all other positions followed by chair sitting (150.079, long sitting (141.495,semi fowler’s position (136.746, supine lying (126.829, side lying (120.162 and head low position (107.829 led to results which were significantly lower than all other positions. Conclusion: More the upright position, higher the PEFR. PEFR is more in standing and Head down position has the lowest PEFR value. Increased lung volumes in standing position can be related to the increased thoracic cavity volume owing to the effect of gravity and the inspiratory muscles would be able to expand the unrestricted thorax in all directions in this position & expiratory muscles attain their optimal length during standing.

  4. Unraveling the Pathophysiology of the Asthma-COPD Overlap Syndrome: Unsuspected Mild Centrilobular Emphysema Is Responsible for Loss of Lung Elastic Recoil in Never Smokers With Asthma With Persistent Expiratory Airflow Limitation.

    Science.gov (United States)

    Gelb, Arthur F; Yamamoto, Alfred; Verbeken, Eric K; Nadel, Jay A

    2015-08-01

    Investigators believe most patients with asthma have reversible airflow obstruction with treatment, despite airway remodeling and hyperresponsiveness. There are smokers with chronic expiratory airflow obstruction despite treatment who have features of both asthma and COPD. Some investigators refer to this conundrum as the asthma-COPD overlap syndrome (ACOS). Furthermore, a subset of treated nonsmokers with moderate to severe asthma have persistent expiratory airflow limitation, despite partial reversibility. This residuum has been assumed to be due to large and especially small airway remodeling. Alternatively, we and others have described reversible loss of lung elastic recoil in acute and persistent loss in patients with moderate to severe chronic asthma who never smoked and its adverse effect on maximal expiratory airflow. The mechanism(s) responsible for loss of lung elastic recoil and persistent expiratory airflow limitation in nonsmokers with chronic asthma consistent with ACOS remain unknown in the absence of structure-function studies. Recently we reported a new pathophysiologic observation in 10 treated never smokers with asthma with persistent expiratory airflow obstruction, despite partial reversibility: All 10 patients with asthma had a significant decrease in lung elastic recoil, and unsuspected, microscopic mild centrilobular emphysema was noted in all three autopsies obtained although it was not easily identified on lung CT scan. These sentinel pathophysiologic observations need to be confirmed to further unravel the epiphenomenon of ACOS. The proinflammatory and proteolytic mechanism(s) leading to lung tissue breakdown need to be further investigated.

  5. Peak expiratory flow mediates the relationship between handgrip strength and timed up and go performance in elderly women, but not men

    Directory of Open Access Journals (Sweden)

    Raphael Mendes Ritti-Dias

    Full Text Available OBJECTIVE: The aim of the present study was to verify if there is sex difference in the associations among handgrip strength, peak expiratory flow (PEF and timed up and go (TUG test results. METHODS: The sample included 288 consecutive elderly men (n=93 and women (n=195. Functional capacity was measured using the TUG test, and muscle strength was measured based on handgrip. Moreover, as a measure of current health status, PEF was evaluated. Linear regression procedures were performed to analyze the relationships between handgrip and both PEF and TUG test results, with adjustment for confounders, and to identify the possible mediating role of PEF in the association between handgrip strength and TUG test results. RESULTS: In men, handgrip strength was associated with both PEF and TUG performance (p<0.01. After adjustment for PEF, the relationship between handgrip strength and TUG performance remained significant. In women, handgrip strength was also associated with both PEF and TUG performance (p<0.01. However, after adjustment for PEF, the relationship between handgrip strength and TUG performance was no longer significant. CONCLUSION: Mobility in the elderly is sex dependent. In particular, PEF mediates the relationship between handgrip strength and TUG performance in women, but not in men.

  6. Study of Peak Expiratory Flow Rate as the Assessment of Lung Function in Occupationally Exposed Petrol Pump Workers of Western Maharashtra

    Directory of Open Access Journals (Sweden)

    Patil Smita V

    2016-04-01

    Full Text Available Background: Fast urbanization trends, rapid industrial growth, globalization, and poor environmental conditions at work places have created a lot of healthrelated issues. Aim and Objectives: The aim of this study is to investigate Peak Expiratory Flow Rate (PEFR as the assessment of lung function in occupationally exposed petrol pump workers and also check whether PEFR increases or decreases with duration of exposure. Material and Methods: The study was conducted on 60 male petrol pump workers between age group of 20-40 years who were working as petrol filling attendants for more than one year from western Maharashtra. 50 normal healthy males with same socioeconomic status were chosen as controls to find out the effect of occupational exposure to petroleum product on PEFR as the assessment of lung function tests. Petrol pump workers were divided into three groups based on their duration of exposure i.e. 1- 5 yrs, 6- 10 yrs and more than 11 years. PEFR of petrol pump workers and control was measured by using a Mini Wright peak flow meter which is a portable device for measuring ventilator functions. Comparisons was done using unpaired t-test for 2 groups comparisons and one way ANOVAfor multiple groups of exposures. Results: The PEFR was significantly lower decrease (p=0.001 around petrol pump workers (389.17 as compared to control (534.2. As year of exposure increased mean value of PEFR was significantly decreased from 452.17, 378.00 and 283.64 respectively in petrol pump workers. Conclusion: The results suggested that respiratory functions i.e. PEFR of occupationally exposed petrol pump workers are significantly reduced as compared to controls, also PEFR is significantly reduced with increase in the duration of exposure.

  7. Limited predictability of maximal muscular pressure using the difference between peak airway pressure and positive end-expiratory pressure during proportional assist ventilation (PAV).

    Science.gov (United States)

    Su, Po-Lan; Kao, Pei-Shan; Lin, Wei-Chieh; Su, Pei-Fang; Chen, Chang-Wen

    2016-11-27

    If the proportional assist ventilation (PAV) level is known, muscular effort can be estimated from the difference between peak airway pressure and positive end-expiratory pressure (PEEP) (ΔP) during PAV. We conjectured that deducing muscle pressure from ΔP may be an interesting method to set PAV, and tested this hypothesis using the oesophageal pressure time product calculation. Eleven mechanically ventilated patients with oesophageal pressure monitoring under PAV were enrolled. Patients were randomly assigned to seven assist levels (20-80%, PAV20 means 20% PAV gain) for 15 min. Maximal muscular pressure calculated from oesophageal pressure (P mus, oes ) and from ΔP (P mus, aw ) and inspiratory pressure time product derived from oesophageal pressure (PTP oes ) and from ΔP (PTP aw ) were determined from the last minute of each level. P mus, oes and PTP oes with consideration of PEEPi were expressed as P mus, oes, PEEPi and PTP oes, PEEPi , respectively. Pressure time product was expressed as per minute (PTP oes , PTP oes, PEEPi , PTP aw ) and per breath (PTP oes, br , PTP oes, PEEPi, br , PTP aw, br ). PAV significantly reduced the breathing effort of patients with increasing PAV gain (PTP oes 214.3 ± 80.0 at PAV20 vs. 83.7 ± 49.3 cmH 2 O•s/min at PAV80, PTP oes, PEEPi 277.3 ± 96.4 at PAV20 vs. 121.4 ± 71.6 cmH 2 O•s/min at PAV80, p PAV and underestimates P mus, oes for moderate-gain to high-gain PAV. An optimal P mus, aw could be achieved in 91% of cases with PAV60. When the PAV gain was adjusted to P mus, aw of 5-10 cmH 2 O, there was a 93% probability of PTP oes PAV has limited accuracy. The extrapolated pressure time product from ΔP is usually less than the pressure time product calculated from oesophageal pressure tracing. However, when the PAV gain was adjusted to P mus, aw of 5-10 cmH 2 O, there was a 90% probability of PTP oes and PTP oes, PEEPi within acceptable ranges. This information should be considered when applying

  8. Limited predictability of maximal muscular pressure using the difference between peak airway pressure and positive end-expiratory pressure during proportional assist ventilation (PAV)

    OpenAIRE

    Su, Po-Lan; Kao, Pei-Shan; Lin, Wei-Chieh; Su, Pei-Fang; Chen, Chang-Wen

    2016-01-01

    Background If the proportional assist ventilation (PAV) level is known, muscular effort can be estimated from the difference between peak airway pressure and positive end-expiratory pressure (PEEP) (?P) during PAV. We conjectured that deducing muscle pressure from ?P may be an interesting method to set PAV, and tested this hypothesis using the oesophageal pressure time product calculation. Methods Eleven mechanically ventilated patients with oesophageal pressure monitoring under PAV were enro...

  9. Diffusion-limited mixing by incompressible flows

    Science.gov (United States)

    Miles, Christopher J.; Doering, Charles R.

    2018-05-01

    Incompressible flows can be effective mixers by appropriately advecting a passive tracer to produce small filamentation length scales. In addition, diffusion is generally perceived as beneficial to mixing due to its ability to homogenize a passive tracer. However we provide numerical evidence that, in cases where advection and diffusion are both actively present, diffusion may produce negative effects by limiting the mixing effectiveness of incompressible optimal flows. This limitation appears to be due to the presence of a limiting length scale given by a generalised Batchelor length (Batchelor 1959 J. Fluid Mech. 5 113–33). This length scale limitation may in turn affect long-term mixing rates. More specifically, we consider local-in-time flow optimisation under energy and enstrophy flow constraints with the objective of maximising the mixing rate. We observe that, for enstrophy-bounded optimal flows, the strength of diffusion may not impact the long-term mixing rate. For energy-constrained optimal flows, however, an increase in the strength of diffusion can decrease the mixing rate. We provide analytical lower bounds on mixing rates and length scales achievable under related constraints (point-wise bounded speed and rate-of-strain) by extending the work of Lin et al (2011 J. Fluid Mech. 675 465–76) and Poon (1996 Commun. PDE 21 521–39).

  10. Acute effects of particulate matter and black carbon from seasonal fires on peak expiratory flow of schoolchildren in the Brazilian Amazon.

    Directory of Open Access Journals (Sweden)

    Ludmilla da Silva Viana Jacobson

    Full Text Available BACKGROUND: Panel studies have shown adverse effects of air pollution from biomass burning on children's health. This study estimated the effect of current levels of outdoor air pollution in the Amazonian dry season on peak expiratory flow (PEF. METHODS: A panel study with 234 schoolchildren from 6 to 15 years old living in the municipality of Tangará da Serra, Brazil was conducted. PEF was measured daily in the dry season in 2008. Mixed-effects models and unified modelling repeated for every child were applied. Time trends, temperature, humidity, and subject characteristics were regarded. Inhalable particulate matter (PM10, fine particulate matter (PM2.5, and black carbon (BC effects were evaluated based on 24-hour exposure lagged by 1 to 5 days and the averages of 2 or 3 days. Polynomial distributed lag models (PDLM were also applied. RESULTS: The analyses revealed reductions in PEF for PM10 and PM2.5 increases of 10 µg/m(3 and 1 µg/m(3 for BC. For PM10, the reductions varied from 0.15 (confidence interval (CI95%: -0.29; -0.01 to 0.25 l/min (CI95%: -0.40; -0.10. For PM2.5, they ranged from 0.46 (CI95%: -0.86 to -0.06 to 0.54 l/min (CI95%:-0.95; -0.14. As for BC, the reduction was approximately 1.40 l/min. In relation to PDLM, adverse effects were noticed in models based on the exposure on the current day through the previous 3 days (PDLM 0-3 and on the current day through the previous 5 days (PDLM 0-5, specially for PM10. For all children, for PDLM 0-5 the global effect was important for PM10, with PEF reduction of 0.31 l/min (CI95%: -0.56; -0.05. Also, reductions in lags 3 and 4 were observed. These associations were stronger for children between 6 and 8 years old. CONCLUSION: Reductions in PEF were associated with air pollution, mainly for lagged exposures of 3 to 5 days and for younger children.

  11. Periodic leg movement, nasal CPAP, and expiratory muscles.

    Science.gov (United States)

    Seo, Won Hee; Guilleminault, Christian

    2012-07-01

    Periodic leg movements (PLMs) may appear during nasal CPAP titration, persisting despite the elimination of hypopneas. Systematic recordings of expiratory abdominal muscles on the right and left sides with surface electromyographic (EMG) electrodes lateral to navel, and close from the lateral side of abdomen, were added during nasal CPAP titration for treatment of obstructive sleep apnea (OSA). Positive airway pressure was titrated during nocturnal polysomnography, based on analysis of the flow curve derived from the CPAP equipment and EEG analysis, including persistence of phases A2 and A3 of the cyclic alternating pattern (CAP). The requirement was to eliminate American Association of Sleep Medicine (AASM)-defined hypopnea and also flow limitation and abnormal EEG patterns. When CPAP reached valid results, it was lowered at the time of awakening by 2 or 3 cm H(2)O, and titration was performed again. Data collected during a 7-month period on adults with a prior diagnosis of OSA who had received treatment with nasal CPAP regardless of age and sex were rendered anonymous and were retrospectively rescored by a blinded investigator. Eighty-one successively seen patients with PLMs during CPAP titration were investigated. Elimination of AASM-defined hypopnea was not sufficient to eliminate the PLMs observed during the titration; higher CPAP eliminated flow limitation and CAP phases A2 and A3 and persisting PLMs. PLMs were associated with simultaneous EMG bursts in expiratory abdominal muscles. The presence of PLMs during CPAP titration indicates the persistence of sleep-disordered breathing. PLMs during CPAP titration are related to the presence of abdominal expiratory muscle activity.

  12. [Relationship between expiratory muscle dysfunction and dynamic hyperinflation in advanced chronic obstructive pulmonary disease].

    Science.gov (United States)

    Mota, Susana; Güell, Rosa; Barreiro, Esther; Casan, Pere; Gea, Joaquim; Sanchis, Joaquín

    2009-10-01

    Dynamic hyperinflation (DH) and expiratory flow limitation (EFL) are physiologically linked and seem to be involved in the genesis of dyspnea and the quality of life (QL) impairment in chronic obstructive pulmonary disease (COPD). Advanced COPD patients often show expiratory muscles dysfunction that could be involved in DH development. Study the relationships between expiratory muscle dysfunction and DH, and their association with dyspnea and QL, in advanced COPD. In 25 patients we measured lung function, exercise capacity (incremental ergometry and walking test), EFL and end-expiratory lung volume (EELV) at rest and during exercise, respiratory muscles strength and endurance, dyspnea and QL (Saint George Respiratory Questionnaire, SGRQ). The patients (mean FEV(1)=31% predicted) showed a moderate decrease of respiratory muscles strength and endurance. Nineteen patients exhibited EFL at rest and 24 at 70% of maximal workload (W(max)). The EELV increased from rest to 70% W(max) (9% of predicted FVC). At 70% W(max) EELV correlated inversely with the EFL amount (rho=-0.42), the inspiratory and expiratory muscles endurance (rho=-0.43 and -0.42 respectively) and y VO(2max) (rho=-0.52). The EELV increase from resting to 70% W(max) correlated with dyspnea (rho=0.53) and the amount of EFL at 70%W(max) with the activity score of SGRQ. The FEV(1,) expiratory muscles endurance and LFE amount were independent predictors of EELV at 70% W(max). In advanced COPD a poorer expiratory muscles endurance is related with higher DH during exercise (and lower EFL), which is correlated with higher dyspnea and worse QL.

  13. Flux Limiter Lattice Boltzmann for Compressible Flows

    International Nuclear Information System (INIS)

    Chen Feng; Li Yingjun; Xu Aiguo; Zhang Guangcai

    2011-01-01

    In this paper, a new flux limiter scheme with the splitting technique is successfully incorporated into a multiple-relaxation-time lattice Boltzmann (LB) model for shacked compressible flows. The proposed flux limiter scheme is efficient in decreasing the artificial oscillations and numerical diffusion around the interface. Due to the kinetic nature, some interface problems being difficult to handle at the macroscopic level can be modeled more naturally through the LB method. Numerical simulations for the Richtmyer-Meshkov instability show that with the new model the computed interfaces are smoother and more consistent with physical analysis. The growth rates of bubble and spike present a satisfying agreement with the theoretical predictions and other numerical simulations. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  14. Potential hazard of the Neopuff T-piece resuscitator in the absence of flow limitation.

    LENUS (Irish Health Repository)

    Hawkes, C P

    2012-01-31

    OBJECTIVE: (1) To assess peak inspiratory pressure (PIP), positive end expiratory pressure (PEEP) and maximum pressure relief (P(max)) at different rates of gas flow, when the Neopuff had been set to function at 5 l\\/min. (2) To assess maximum PIP and PEEP at a flow rate of 10 l\\/min with a simulated air leak of 50%. DESIGN: 5 Neopuffs were set to a PIP of 20, PEEP of 5 and P(max) of 30 cm H(2)O at a gas flow of 5 l\\/min. PIP, PEEP and P(max) were recorded at flow rates of 10, 15 l\\/min and maximum flow. Maximum achievable pressures at 10 l\\/min gas flow, with a 50% air leak, were measured. RESULTS: At gas flow of 15 l\\/min, mean PEEP increased to 20 (95% CI 20 to 21), PIP to 28 (95% CI 28 to 29) and the P(max) to 40 cm H(2)O (95% CI 38 to 42). At maximum flow (85 l\\/min) a PEEP of 71 (95% CI 51 to 91) and PIP of 92 cm H(2)O (95% CI 69 to 115) were generated. At 10 l\\/min flow, with an air leak of 50%, the maximum PEEP and PIP were 21 (95% CI 19 to 23) and 69 cm H(2)O (95% CI 66 to 71). CONCLUSIONS: The maximum pressure relief valve is overridden by increasing the rate of gas flow and potentially harmful PIP and PEEP can be generated. Even in the presence of a 50% gas leak, more than adequate pressures can be provided at 10 l\\/min gas flow. We recommend the limitation of gas flow to a rate of 10 l\\/min as an added safety mechanism for this device.

  15. Negative expiratory pressure (NEP) parameters can predict obstructive sleep apnea syndrome in snoring patients.

    Science.gov (United States)

    Rouatbi, Sonia; Tabka, Zouhair; Dogui, Mohamed; Abdelghani, Ahmed; Guénard, Hervé

    2009-01-01

    The objective of this study was to assess whether parameters of the negative expiratory pressure (NEP) technique are able to detect obstructive sleep apnea syndrome (OSAS) in snoring patients. A cross-sectional study included 42 OSAS patients diagnosed by polysomnography (PSG), 34 simple snorers, and 32 healthy subjects. Lung function was measured by using a plethysmograph and the NEP technique was performed with the patient in the seated and supine positions in a random order. The depression was fixed to 5 cmH(2)O. All patients had normal forced expiratory flow/volume loops. Apneic patients had lower Dflow in both positions with a number of oscillations on the expiratory curve obtained with NEP and an expiratory flow limitation (EFL) in the supine position higher than that of other groups (p < 0.05). Changing from the sitting to the supine position raised the EFL of the three groups, with a significant decrease in Dflow and an increase in the number of oscillations in snoring and OSAS patients (p < 0.05). The analysis of variance showed that only the number of oscillations was significantly different between apneic and snoring patients. NEP constitutes a simple and useful tool for the screening OSAS by EFL, especially the number of oscillations obtained with NEP.

  16. Infant ventilator design: performance during expiratory limb occlusion.

    Science.gov (United States)

    Hall, M W; Peevy, K J

    1983-01-01

    We examined the specifications and design of the inspiratory pressure regulating valve of 8 continuous flow, pressure-limited infant ventilators. Two pressure regulating designs are currently available; one placing the primary pressure regulating valve on the inspiratory limb, the other placing it on the expiratory limb. Seven ventilators incorporate the latter design to limit inspiratory pressure and must have a safety pressure-relief valve located on the inspiratory limb to vent pressure in case of circuit occlusion. These pressure-relief valves are generally set by the manufacturer far in excess of pressures normally used for infant ventilation. Alarm systems are often absent or inadequate to warn of high pressure conditions during circuit obstruction. A case report detailing the fatal complication of prolonged excessive airway pressure during circuit occlusion is presented. Improvements in the pressure-relief valve designs currently available are possible, and may be necessary to provide adequate protection from barotrauma. The majority of infant ventilators currently available expose the patient to unnecessary excessive airway pressures in the case of expiratory limb occlusion, and the lack of alarm systems may leave the operator unaware of malfunction.

  17. Pico do fluxo expiratório na avaliação da função pulmonar na fibrose cística Peak expiratory flow rate in the management of cystic fibrosis

    Directory of Open Access Journals (Sweden)

    Paulo A.M. Camargos

    2002-02-01

    Full Text Available Objetivo: avaliar o valor do pico de fluxo expiratório, obtido através de medidores portáteis, como método alternativo de acompanhamento da função pulmonar na fibrose cística. Métodos: quarenta e nove pacientes, de 5 a 19 anos, clinicamente estáveis e aptos a realizar a manobra para obtenção do pico do fluxo foram incluídos no estudo. Na mesma visita, pontuou-se o escore de Shwachman-Kulczycki e registrou-se o valor do pico do fluxo expiratório. Analisou-se a correlação entre esses dois parâmetros pela regressão linear, com nível de significância de P = 0,05. Resultados: obteve-se uma correlação discreta, mas estatisticamente significante, entre os valores absolutos e percentuais desse parâmetro funcional com o escore clínico-radiológico (r = 0,31, P = 0,02 e r = 0,30, P = 0,03, respectivamente. Conclusões: conclui-se que a significância estatística observada não corresponde necessariamente a uma relevância clínica e, portanto, a função pulmonar na fibrose cística deve ser avaliada pela espirometria convencional.Objective: to verify the role of peak expiratory flow, measured through portable meters, as an alternative test to assess pulmonary disease in cystic fibrosis. Methods: forty-nine patients aged five to 19 years old in stable health condition and able to perform the peak expiratory flow maneuver were included. In the same visit, Shwachman-Kulczycki score was recorded. Linear regression was used to assess the correlation between the Shwachman-Kulczycki score and the peak expiratory flow rate. A P value of 0.05 was considered to be significant.Results: a slight, but statistically significant correlation between absolute and percent values for this functional parameter and the Shwachman-Kulczycki score (r = 0.31, P = 0.02 and r = 0.30, P = 0.03, respectively was found. Conclusions: although this correlation was statistically significant, these findings are not clinically relevant, i.e., the lung involvement

  18. A study of experimental acute lung injury in pigs on zero end-expiratory pressure.

    Science.gov (United States)

    Guérin, Claude; Levrat, Albrice; Pontier, Sandrine; Annat, Guy

    2008-03-01

    Tidal expiratory flow limitation (EFL) has been reported in humans with acute lung injury (ALI) and assumed to be associated with small airway closure. Detection of EFL is important because by selecting positive end-expiratory pressure at such a level that EFL is no longer present in the tidal breath, the repeated opening and closure of small airways can be prevented. The objective of this study was to investigate the occurrence of EFL in two experimental models of ALI. Ten female piglets. Animals were anaesthetized, tracheotomized and mechanically ventilated on zero end-expiratory pressure. Acute lung injury was induced by oleic acid (OA) (n = 5) or saline lavage (SL) (n = 5). Tidal EFL was assessed by the negative expiratory pressure test. Lung and chest wall mechanics were partitioned using an oesophageal balloon. Resistance and static elastance were assessed by a rapid airway occlusion technique at baseline ventilatory settings. There was no EFL at any time before and after ALI in both models. This may be due to an increased elastance which promoted higher expiratory flow after ALI and to a decreased chest wall to lung static elastance ratio which could favour small airways patency. The similar increase in total lung resistance, in the two models, after ALI was mostly due to an increased airway resistance in the OA model and to the lung tissue resistance in the SL model. Tidal EFL was not detected in experimental ALI. This finding casts some doubt about the usefulness of some experimental models of ALI to mimic some reported findings in human ALI.

  19. Limited bronchoconstriction to methacholine using partial flow-volume curves in nonasthmatic subjects

    NARCIS (Netherlands)

    Sterk, P. J.; Daniel, E. E.; Zamel, N.; Hargreave, F. E.

    1985-01-01

    We investigated whether the plateau of the dose-response to nonsensitizing stimuli, such as methacholine, could be explained by the airway dilation that follows lung inflation in nonasthmatics. We used maximal expiratory partial flow-volume curves to measure the response of the airways to doubling

  20. What's in a name? Expiratory tracheal narrowing in adults explained

    International Nuclear Information System (INIS)

    Leong, P.; Bardin, P.G.; Lau, K.K.

    2013-01-01

    Tracheomalacia, tracheobronchomalacia, and excessive dynamic airway collapse are all terms used to describe tracheal narrowing in expiration. The first two describe luminal reduction from cartilage softening and the latter refers to luminal reduction from exaggerated posterior membrane movement. Expiratory tracheal narrowing is a frequent occurrence that can cause symptoms of airway obstruction, such as dyspnoea, wheeze, and exercise intolerance. The accurate diagnosis and quantification of expiratory tracheal narrowing has important aetiological, therapeutic, and prognostic implications. The reference standard for diagnosis has traditionally been bronchoscopy; however, this method has significant limitations. Expiratory tracheal disorders are readily detected by four-dimensional dynamic volume multidetector computed tomography (4D-CT), an emerging, non-invasive method that will potentially enable detection and quantification of these conditions. This review discusses the morphological forms of expiratory tracheal narrowing and demonstrates the utility of 4D-CT in the diagnosis, quantification, and treatment of these important conditions

  1. Estimating Postsecondary Student Flow with Limited Data.

    Science.gov (United States)

    Rumpf, David L.; And Others

    1987-01-01

    A model is presented that combines a polynomial lag econometric model with a goal programming model to satisfy the known conditions while making efficient use of limited data. The model is applied to data for a large public university. (Author/MLW)

  2. Reduced Expiratory Flow Rate among Heavy Smokers Increases Lung Cancer Risk. Results from the National Lung Screening Trial-American College of Radiology Imaging Network Cohort.

    Science.gov (United States)

    Hopkins, Raewyn J; Duan, Fenghai; Chiles, Caroline; Greco, Erin M; Gamble, Greg D; Aberle, Denise; Young, Robert P

    2017-03-01

    Although epidemiological studies consistently show that chronic obstructive pulmonary disease is associated with an increased risk of lung cancer, debate exists as to whether there is a linear relationship between the severity of airflow limitation and lung cancer risk. We examined this in a large, prospective study of older heavy smokers from the American College of Radiology Imaging Network subcohort of the National Lung Screening Trial (ACRIN). Airflow limitation was defined by prebronchodilator spirometry subgrouped according to Global Initiative for Chronic Obstructive Lung Disease (GOLD) grades 1-4. In the National Lung Screening Trial-ACRIN cohort of 18,473 screening participants, 6,436 had airflow limitation (35%) and 12,037 (65%) had no airflow limitation. From these groups, 758 lung cancer cases were prospectively identified. Participants with airflow limitation were stratified according to GOLD groups 1 (n = 1,607), 2 (n = 3,528), 3 (n = 1,083), and 4 (n = 211). Lung cancer incidence at study end (mean follow-up, 6.4 yr) was compared between the GOLD groups and those with no airflow limitation (referent group). Compared with those with no airflow limitation, where lung cancer incidence was 3.78/1,000 person years, incidence rates increased in a simple linear relationship: GOLD 1 (6.27/1,000 person yr); GOLD 2 (7.86/1,000 person yr); GOLD 3 (10.71/1,000 person yr); and GOLD 4 (13.25/1,000 person yr). All relationships were significant versus the reference group at a P value of 0.0001 or less. In a large prospective study of high-risk cigarette smokers, we report a strong linear relationship between increasing severity of airflow limitation and risk of lung cancer.

  3. Pedestrian Flow in the Mean Field Limit

    KAUST Repository

    Haji Ali, Abdul Lateef

    2012-11-01

    We study the mean-field limit of a particle-based system modeling the behavior of many indistinguishable pedestrians as their number increases. The base model is a modified version of Helbing\\'s social force model. In the mean-field limit, the time-dependent density of two-dimensional pedestrians satisfies a four-dimensional integro-differential Fokker-Planck equation. To approximate the solution of the Fokker-Planck equation we use a time-splitting approach and solve the diffusion part using a Crank-Nicholson method. The advection part is solved using a Lax-Wendroff-Leveque method or an upwind Backward Euler method depending on the advection speed. Moreover, we use multilevel Monte Carlo to estimate observables from the particle-based system. We discuss these numerical methods, and present numerical results showing the convergence of observables that were calculated using the particle-based model as the number of pedestrians increases to those calculated using the probability density function satisfying the Fokker-Planck equation.

  4. Counter-current flow limited CHF in thin rectangular channels

    International Nuclear Information System (INIS)

    Cheng, L.Y.

    1990-01-01

    An analytical expression for counter-current-flow-limitation (CCFL) was used to predict critical heat flux (CHF) for downward flow in thin vertical rectangular channels which are prototypes of coolant channels in test and research nuclear reactors. Top flooding is the mechanism for counter-current flow limited CHF. The CCFL correlation also was used to determine the circulation and flooding-limited CHF. Good agreements were observed between the period the model predictions and data on the CHF for downflow. The minimum CHF for downflow is lower than the flooding-limited CHF and it is predicted to occur at a liquid flow rate higher than that at the flooding limit. 17 refs., 7 figs

  5. Abdominal wall reconstruction for large incisional hernia restores expiratory lung function

    DEFF Research Database (Denmark)

    Jensen, Kristian K; Backer, Vibeke; Jorgensen, Lars N

    2017-01-01

    (horizontal fascial defect width >10 cm) were compared with 18 patients with an intact abdominal wall who underwent colorectal resection. Patients were examined pre- and 1-year postoperatively. Examined measures included forced vital capacity, forced expiratory volume in first second, peak expiratory flow...

  6. Cost-effectiveness of a nurse-led telemonitoring intervention based on peak expiratory flow measurements in asthmatics: results of a randomised controlled trial

    Directory of Open Access Journals (Sweden)

    Wouters Emiel FM

    2007-07-01

    Full Text Available Abstract Background Asthma is a chronic lung disease in which recurrent asthma symptoms create a substantial burden to individuals and their families. At the same time the economic burden associated with asthma is considerable. Methods The cost-effectiveness study was part of a single centre prospective randomised controlled trial comparing a nurse-led telemonitoring programme to usual care in a population of asthmatic outpatients. The study included 109 asthmatic outpatients (56 children; 53 adults. The duration of follow-up was 12 months, and measurements were performed at baseline, 4, 8, and 12 months. Patients were asked to transfer their monitor data at least twice daily and by judging the received data and following a stepwise intervention protocol a nurse was able to act as the main caregiver in the intervention group. In both groups the EQ-5D and the SF-6D were used to obtain estimates of health state utilities. One year health care costs, patient and family costs, and productivity losses were calculated. The mean incremental costs were weighted against the mean incremental effect in terms of QALY. Results The study population generally represented mild to moderate asthmatics. No significant differences were found between the groups with regard to the generic quality of life. Overall, the mean health care costs per patient were higher in the intervention group than in the control group. The intervention costs mainly caused the cost difference between the groups. The intervention costs the society € 31,035/QALY gained with regard to adults and with regard to children € 59,071/QALY gained. Conclusion If the outcome is measured by generic quality of life the nurse-led telemonitoring programme is of limited cost-effectiveness in the study population. From the societal perspective the probability of the programme being cost-effective compared to regular care was 85% at a ceiling ratio of € 80,000/QALY gained among the adults and 68

  7. Tracheal sound parameters of respiratory cycle phases show differences between flow-limited and normal breathing during sleep

    International Nuclear Information System (INIS)

    Kulkas, A; Huupponen, E; Virkkala, J; Saastamoinen, A; Rauhala, E; Tenhunen, M; Himanen, S-L

    2010-01-01

    The objective of the present work was to develop new computational parameters to examine the characteristics of respiratory cycle phases from the tracheal breathing sound signal during sleep. Tracheal sound data from 14 patients (10 males and 4 females) were examined. From each patient, a 10 min long section of normal and a 10 min section of flow-limited breathing during sleep were analysed. The computationally determined proportional durations of the respiratory phases were first investigated. Moreover, the phase durations and breathing sound amplitude levels were used to calculate the area under the breathing sound envelope signal during inspiration and expiration phases. An inspiratory sound index was then developed to provide the percentage of this type of area during the inspiratory phase with respect to the combined area of inspiratory and expiratory phases. The proportional duration of the inspiratory phase showed statistically significantly higher values during flow-limited breathing than during normal breathing and inspiratory pause displayed an opposite difference. The inspiratory sound index showed statistically significantly higher values during flow-limited breathing than during normal breathing. The presented novel computational parameters could contribute to the examination of sleep-disordered breathing or as a screening tool

  8. Determining the Limiting Current Density of Vanadium Redox Flow Batteries

    Directory of Open Access Journals (Sweden)

    Jen-Yu Chen

    2014-09-01

    Full Text Available All-vanadium redox flow batteries (VRFBs are used as energy storage systems for intermittent renewable power sources. The performance of VRFBs depends on materials of key components and operating conditions, such as current density, electrolyte flow rate and electrolyte composition. Mass transfer overpotential is affected by the electrolyte flow rate and electrolyte composition, which is related to the limiting current density. In order to investigate the effect of operating conditions on mass transport overpotential, this study established a relationship between the limiting current density and operating conditions. First, electrolyte solutions with different states of charge were prepared and used for a single cell to obtain discharging polarization curves under various operating conditions. The experimental results were then analyzed and are discussed in this paper. Finally, this paper proposes a limiting current density as a function of operating conditions. The result helps predict the effect of operating condition on the cell performance in a mathematical model.

  9. The limiting current in a one-dimensional situation: Transition from a space charge limited to magnetically limited flow

    International Nuclear Information System (INIS)

    Kumar, Raghwendra; Biswas, Debabrata

    2008-01-01

    For a nonrelativistic electron beam propagating in a cylindrical drift tube, it is shown that the limiting current density does not saturate to the electrostatic one-dimensional (1D) estimate with increasing beam radius. Fully electromagnetic particle-in-cell (PIC) simulation studies show that beyond a critical aspect ratio, the limiting current density is lower than the 1D electrostatic prediction. The lowering in the limiting current density is found to be due to the transition from the space charge limited to magnetically limited flow. An adaptation of Alfven's single particle trajectory method is used to estimate the magnetically limited current as well as the critical radius beyond which the flow is magnetically limited in a drift tube. The predictions are found to be in close agreement with PIC simulations

  10. Use of tidal breathing curves for evaluating expiratory airway obstruction in infants.

    Science.gov (United States)

    Hevroni, Avigdor; Goldman, Aliza; Blank-Brachfeld, Miriam; Abu Ahmad, Wiessam; Ben-Dov, Lior; Springer, Chaim

    2018-01-15

    To evaluate tidal breathing (TB) flow-volume and flow-time curves for identification of expiratory airway obstruction in infants. Pulmonary function tests were analyzed retrospectively in 156 infants aged 3-24 months with persistent or recurrent respiratory complaints. Parameters derived from TB curves were compared to maximal expiratory flow at functional residual capacity ([Formula: see text]maxFRC) measured by rapid thoracoabdominal compression technique. Analyzed parameters were: inspiratory time (t I ), expiratory time (t E ), tidal volume, peak tidal expiratory flow (PTEF), time to peak tidal expiratory flow (t PTEF ), expiratory flow when 50% and 25% of tidal volume remains in the lungs (FEF 50 , FEF 25 , respectively), and the ratios t PTEF /t E , t I /t E , FEF 50 /PTEF, and FEF 25 /PTEF. Statistical comparisons between flow indices and TB parameters were performed using mean squared error and Pearson's sample correlation coefficient. The study population was also divided into two groups based on severity of expiratory obstruction (above or below z-score for [Formula: see text]maxFRC of -2) to generate receiver operating characteristic (ROC) curves and calculate discriminatory values between the groups. TB parameters that were best correlated to [Formula: see text]maxFRC were: t PTEF /t E , FEF 50 /PTEF, and FEF 25 /PTEF, with r = 0.61, 0.67, 0.65, respectively (p < 0.0001 for all). ROC curves for FEF 50 /PTEF, FEF 25 /PTEF and t PTEF /t E showed areas under the curve of 0.813, 0.797, and 0.796, respectively. Cutoff value z-scores of -0.35, -0.34, and -0.43 for these three parameters, respectively, showed an 86% negative predictive value for severe airway obstructions. TB curves can assist in ruling out severe expiratory airway obstruction in infants.

  11. Effects of positive end-expiratory pressure on renal function.

    Science.gov (United States)

    Järnberg, P O; de Villota, E D; Eklund, J; Granberg, P O

    1978-01-01

    The effects were studied positive end-expiratory pressure (PEEP) on renal function in eight patients with acute respiratory failure, requiring mechanical ventilation. On application of PEEP + 10 cm H2O, central venous pressure increased, systolic blood pressure decreased, urine flow and PAH-clearance were reduced, while inulin clearance remained stable. There was a marked increase in fractional sodium reabsorption and a concurrent decrease in fractional osmolal excretion. Fractional free-water clearance and the ratio UOsm/POsm did change.

  12. Correlation of Normal Gravity Mixed Convection Blowoff Limits with Microgravity Forced Flow Blowoff Limits

    Science.gov (United States)

    Marcum, Jeremy W.; Olson, Sandra L.; Ferkul, Paul V.

    2016-01-01

    The axisymmetric rod geometry in upward axial stagnation flow provides a simple way to measure normal gravity blowoff limits to compare with microgravity Burning and Suppression of Solids - II (BASS-II) results recently obtained aboard the International Space Station. This testing utilized the same BASS-II concurrent rod geometry, but with the addition of normal gravity buoyant flow. Cast polymethylmethacrylate (PMMA) rods of diameters ranging from 0.635 cm to 3.81 cm were burned at oxygen concentrations ranging from 14 to 18% by volume. The forced flow velocity where blowoff occurred was determined for each rod size and oxygen concentration. These blowoff limits compare favorably with the BASS-II results when the buoyant stretch is included and the flow is corrected by considering the blockage factor of the fuel. From these results, the normal gravity blowoff boundary for this axisymmetric rod geometry is determined to be linear, with oxygen concentration directly proportional to flow speed. We describe a new normal gravity 'upward flame spread test' method which extrapolates the linear blowoff boundary to the zero stretch limit in order to resolve microgravity flammability limits-something current methods cannot do. This new test method can improve spacecraft fire safety for future exploration missions by providing a tractable way to obtain good estimates of material flammability in low gravity.

  13. Weighted Polynomial Approximation for Automated Detection of Inspiratory Flow Limitation

    Directory of Open Access Journals (Sweden)

    Sheng-Cheng Huang

    2017-01-01

    Full Text Available Inspiratory flow limitation (IFL is a critical symptom of sleep breathing disorders. A characteristic flattened flow-time curve indicates the presence of highest resistance flow limitation. This study involved investigating a real-time algorithm for detecting IFL during sleep. Three categories of inspiratory flow shape were collected from previous studies for use as a development set. Of these, 16 cases were labeled as non-IFL and 78 as IFL which were further categorized into minor level (20 cases and severe level (58 cases of obstruction. In this study, algorithms using polynomial functions were proposed for extracting the features of IFL. Methods using first- to third-order polynomial approximations were applied to calculate the fitting curve to obtain the mean absolute error. The proposed algorithm is described by the weighted third-order (w.3rd-order polynomial function. For validation, a total of 1,093 inspiratory breaths were acquired as a test set. The accuracy levels of the classifications produced by the presented feature detection methods were analyzed, and the performance levels were compared using a misclassification cobweb. According to the results, the algorithm using the w.3rd-order polynomial approximation achieved an accuracy of 94.14% for IFL classification. We concluded that this algorithm achieved effective automatic IFL detection during sleep.

  14. Calculation of Wind Power Limit adjusting the Continuation Power Flow

    International Nuclear Information System (INIS)

    Santos Fuentefria, Ariel; Castro Fernández, Miguel; Martínez García, Antonio

    2012-01-01

    The wind power insertion in the power system is an important issue and can create some instability problems in voltage and system frequency due to stochastic origin of wind. Know the Wind Power Limit is a very important matter. Existing in bibliography a few methods for calculation of wind power limit. The calculation is based in static constrains, dynamic constraints or both. In this paper is developed a method for the calculation of wind power limit using some adjust in the continuation power flow, and having into account the static constrains. The method is complemented with Minimal Power Production Criterion. The method is proved in the Isla de la Juventud Electric System. The software used in the simulations was the Power System Analysis Toolbox (PSAT). (author)

  15. Maximum static inspiratory and expiratory pressures with different lung volumes

    Directory of Open Access Journals (Sweden)

    Johnson Monique M

    2006-05-01

    Full Text Available Abstract Background Maximum pressures developed by the respiratory muscles can indicate the health of the respiratory system, help to determine maximum respiratory flow rates, and contribute to respiratory power development. Past measurements of maximum pressures have been found to be inadequate for inclusion in some exercise models involving respiration. Methods Maximum inspiratory and expiratory airway pressures were measured over a range of lung volumes in 29 female and 19 male adults. A commercial bell spirometry system was programmed to occlude airflow at nine target lung volumes ranging from 10% to 90% of vital capacity. Results In women, maximum expiratory pressure increased with volume from 39 to 61 cmH2O and maximum inspiratory pressure decreased with volume from 66 to 28 cmH2O. In men, maximum expiratory pressure increased with volume from 63 to 97 cmH2O and maximum inspiratory pressure decreased with volume from 97 to 39 cmH2O. Equations describing pressures for both sexes are: Pe/Pmax = 0.1426 Ln( %VC + 0.3402 R2 = 0.95 Pi/Pmax = 0.234 Ln(100 - %VC - 0.0828 R2 = 0.96 Conclusion These results were found to be consistent with values and trends obtained by other authors. Regression equations may be suitable for respiratory mechanics models.

  16. Peak-counts blood flow model-errors and limitations

    International Nuclear Information System (INIS)

    Mullani, N.A.; Marani, S.K.; Ekas, R.D.; Gould, K.L.

    1984-01-01

    The peak-counts model has several advantages, but its use may be limited due to the condition that the venous egress may not be negligible at the time of peak-counts. Consequently, blood flow measurements by the peak-counts model will depend on the bolus size, bolus duration, and the minimum transit time of the bolus through the region of interest. The effect of bolus size on the measurement of extraction fraction and blood flow was evaluated by injecting 1 to 30ml of rubidium chloride in the femoral vein of a dog and measuring the myocardial activity with a beta probe over the heart. Regional blood flow measurements were not found to vary with bolus sizes up to 30ml. The effect of bolus duration was studied by injecting a 10cc bolus of tracer at different speeds in the femoral vein of a dog. All intravenous injections undergo a broadening of the bolus duration due to the transit time of the tracer through the lungs and the heart. This transit time was found to range from 4-6 second FWHM and dominates the duration of the bolus to the myocardium for up to 3 second injections. A computer simulation has been carried out in which the different parameters of delay time, extraction fraction, and bolus duration can be changed to assess the errors in the peak-counts model. The results of the simulations show that the error will be greatest for short transit time delays and for low extraction fractions

  17. Abdominal wall reconstruction for large incisional hernia restores expiratory lung function.

    Science.gov (United States)

    Jensen, Kristian K; Backer, Vibeke; Jorgensen, Lars N

    2017-02-01

    Respiratory complications secondary to intermittent intra-abdominal hypertension and/or atelectasis are common after abdominal wall reconstruction for large incisional hernias. It is unknown if the respiratory function of this patient group is affected long term or impairs activities of daily living. We hypothesized that abdominal wall reconstruction for large incisional hernia would not lead to improved, long-term pulmonary function or respiratory quality of life. Eighteen patients undergoing open abdominal wall reconstruction with mesh for a large incisional hernia (horizontal fascial defect width >10 cm) were compared with 18 patients with an intact abdominal wall who underwent colorectal resection. Patients were examined pre- and 1-year postoperatively. Examined measures included forced vital capacity, forced expiratory volume in first second, peak expiratory flow, maximal in- and expiratory mouth pressure, and 2 validated questionnaires on respiratory quality of life. In order to decrease heterogeneity, objectively examined parameters were presented relative to the predicted values, which were normality adjusted pulmonary measures. At 1-year follow-up, the abdominal wall reconstruction group showed significant improvement in percent predicted peak expiratory flow and maximal expiratory mouth pressure, whereas all other measurements of lung function remained unchanged. Respiratory quality of life did not change significantly. Patients who underwent abdominal wall reconstruction showed a significantly greater improvement of percent predicted peak expiratory flow compared with patients undergoing colorectal resection. Abdominal wall reconstruction for large incisional hernia improved long-term expiratory lung function. Respiratory quality of life did not change significantly after abdominal wall reconstruction. Copyright © 2016 Elsevier Inc. All rights reserved.

  18. Estimation of tracheal pressure and imposed expiratory work of breathing by the endotracheal tube, heat and moisture exchanger, and ventilator during mechanical ventilation.

    Science.gov (United States)

    Uchiyama, Akinori; Yoshida, Takeshi; Yamanaka, Hidenori; Fujino, Yuji

    2013-07-01

    The resistance of the endotracheal tube (ETT), the heat and moisture exchanger (HME), and the ventilator may affect the patient's respiratory status. Although previous studies examined the inspiratory work of breathing (WOB), investigation of WOB in the expiratory phase is rare. We estimated tracheal pressure at the tip of the ETT (Ptrach) and calculated expiratory WOB imposed by the ETT, the HME, and the expiratory valve. We examined imposed expiratory WOB in patients under a continuous mandatory ventilation (CMV) mode and during spontaneous breathing trials (SBTs). We hypothesized that imposed expiratory WOB would increase with heightened ventilatory demand. We measured airway pressure (Paw) and respiratory flow (V). We estimated Ptrach using the equation Ptrach = Paw - K1 × V(K2) - 2.70 × V(L/s)(1.42). K1 and K2 were determined by the inner diameter (ID) of the ETT. Imposed expiratory WOB was calculated from the area of Ptrach above PEEP versus lung volume. We examined imposed expiratory WOB and imposed expiratory resistance in relation to mean expiratory flow. We examined 28 patients under CMV mode, and 29 during SBT. During both CMV and SBT, as mean expiratory flow increased, imposed expiratory WOB increased. The regression curves between mean expiratory flow (x) (L/s) and imposed expiratory WOB (y) (J/L) were y = 1.35x(0.83) (R(2) = 0.79) for 7 mm ID ETT under CMV, y = 1.12x(0.82) (R(2) = 0.73) for 8 mm ID ETT under CMV, y = 1.07x(1.04) (R(2) = 0.85) for 7 mm ID ETT during SBT, and y = 0.84x(0.93) (R(2) = 0.75) for 8 mm ID ETT during SBT. Levels of imposed expiratory WOB were affected by ETT diameter and ventilator mode. The reason for increasing imposed expiratory WOB was an increase in expiratory resistance imposed by the ETT and HME. Under mechanical ventilation, imposed expiratory WOB should be considered in patients with higher minute ventilation.

  19. Effects of expiratory muscle training on the frail elderly's respiratory function.

    Science.gov (United States)

    Chigira, Yusuke; Miyazaki, Ikuri; Izumi, Masataka; Oda, Takahiro

    2018-02-01

    [Purpose] The present study examined the effects of expiratory muscle training on elderly day care service users, who had been classified into Care Grades 1 and 2 based on Japan's long-term care insurance system. [Subjects and Methods] Intervention was provided for 29 Care Grade 1 or 2 day care service users. During intervention, expiratory muscle training was performed by slowly expiring using the abdominal muscles and a device after maximal inspiration. Each intervention session lasted for approximately 10 minutes, and 2 sessions were held weekly for 3 months to compare respiratory function test values before and after intervention. [Results] The results were favorable. The vital capacity (VC) and peak expiratory flow (PEF) significantly varied between before and after intervention. [Conclusion] Expiratory muscle training generally improved their respiratory function, particularly their VC and PEF that significantly varied between before and after intervention. As both of these items influence the cough capacity, they may be key to the prevention of aspiration pneumonia. Expiratory muscle training may also contribute to activities of daily living (ADL) and the quality of life, and it is expected to play an important role in rehabilitation as a field of preventive medicine.

  20. The role of heater thermal response in reactor thermal limits during oscillartory two-phase flows

    Energy Technology Data Exchange (ETDEWEB)

    Ruggles, A.E.; Brown, N.W. [Univ. of Tennessee, Knoxville, TN (United States); Vasil`ev, A.D. [Nuclear Safety Institute, Moscow, (Russian Federation); Wendel, M.W. [Oak Ridge National Lab., TN (United States)

    1995-09-01

    Analytical and numerical investigations of critical heat flux (CHF) and reactor thermal limits are conducted for oscillatory two-phase flows often associated with natural circulation conditions. It is shown that the CHF and associated thermal limits depend on the amplitude of the flow oscillations, the period of the flow oscillations, and the thermal properties and dimensions of the heater. The value of the thermal limit can be much lower in unsteady flow situations than would be expected using time average flow conditions. It is also shown that the properties of the heater strongly influence the thermal limit value in unsteady flow situations, which is very important to the design of experiments to evaluate thermal limits for reactor fuel systems.

  1. Observational study on efficacy of negative expiratory pressure test proposed as screening for obstructive sleep apnea syndrome among commercial interstate bus drivers - protocol study

    Directory of Open Access Journals (Sweden)

    Hirata Raquel P

    2011-12-01

    Full Text Available Abstract Background Obstructive sleep apnea (OSA is a respiratory disease characterized by the collapse of the extrathoracic airway and has important social implications related to accidents and cardiovascular risk. The main objective of the present study was to investigate whether the drop in expiratory flow and the volume expired in 0.2 s during the application of negative expiratory pressure (NEP are associated with the presence and severity of OSA in a population of professional interstate bus drivers who travel medium and long distances. Methods/Design An observational, analytic study will be carried out involving adult male subjects of an interstate bus company. Those who agree to participate will undergo a detailed patient history, physical examination involving determination of blood pressure, anthropometric data, circumference measurements (hips, waist and neck, tonsils and Mallampati index. Moreover, specific questionnaires addressing sleep apnea and excessive daytime sleepiness will be administered. Data acquisition will be completely anonymous. Following the medical examination, the participants will perform a spirometry, NEP test and standard overnight polysomnography. The NEP test is performed through the administration of negative pressure at the mouth during expiration. This is a practical test performed while awake and requires little cooperation from the subject. In the absence of expiratory flow limitation, the increase in the pressure gradient between the alveoli and open upper airway caused by NEP results in an increase in expiratory flow. Discussion Despite the abundance of scientific evidence, OSA is still underdiagnosed in the general population. In addition, diagnostic procedures are expensive, and predictive criteria are still unsatisfactory. Because increased upper airway collapsibility is one of the main determinants of OSA, the response to the application of NEP could be a predictor of this disorder. With the

  2. Effects of duty cycle and positive end-expiratory pressure on mucus clearance during mechanical ventilation*.

    Science.gov (United States)

    Li Bassi, Gianluigi; Saucedo, Lina; Marti, Joan-Daniel; Rigol, Montserrat; Esperatti, Mariano; Luque, Nestor; Ferrer, Miquel; Gabarrus, Albert; Fernandez, Laia; Kolobow, Theodor; Torres, Antoni

    2012-03-01

    During mechanical ventilation, air flows may play a role in mucus transport via two-phase gas liquid flow. The aim of this study was to evaluate effects of duty cycles and positive end-expiratory pressure on mucus clearance in pigs using mechanical ventilation, and to assess their safety. Prospective randomized animal study. Animal research facility, University of Barcelona, Spain. Eight healthy pigs. Pigs were intubated and on volume-control mechanical ventilation for up to 84 hrs. After 4, 24, 48, and 72 hrs of mechanical ventilation, six levels of duty cycle (0.26, 0.33, 0.41, 0.50, 0.60, and 0.75) with no associated positive end-expiratory pressure or 5 cm H2O of positive end-expiratory pressure were randomly applied. Surgical bed was oriented 30 degrees in the reverse Trendelenburg position, as in the semirecumbent position. Inspiratory and expiratory flows and hemodynamics were measured after each 30-min ventilation period. Mucus movement was assessed through fluoroscopy tracking of radio-opaque markers. Mucus velocity was described by a positive vector (toward the glottis) or negative vector (toward the lungs). No effect of positive end-expiratory pressure was found; however, as duty cycle was increasingly prolonged, a trend toward reduced velocity of mucus moving toward the lungs and increased outward mucus velocity was found (p = .064). Two clusters of mucus velocities were identified as duty cycle was prolonged beyond 0.41. Thus, duty cycle >0.41 increased mean expiratory-inspiratory flow bias from -4.1 ± 4.6 to 7.9 ± 5.9 L/min (p < .0001) and promoted outward mucus velocity from -0.22 ± 1.71 mm/min (range, -5.78 to 2.42) to 0.53 ± 1.06 mm/min (-1.91 to 3.88; p = .0048). Duty cycle of 0.75 resulted in intrinsic positive end-expiratory pressure (2.1 ± 1.1 cm H2O [p < .0001] vs. duty cycle 0.26-0.5), with no hemodynamic compromise. In the semirecumbent position, mucus clearance is improved with prolongation of the duty cycle. However, in clinical

  3. Endocannabinoids Control Platelet Activation and Limit Aggregate Formation under Flow

    Science.gov (United States)

    De Angelis, Valentina; Koekman, Arnold C.; Weeterings, Cees; Roest, Mark; de Groot, Philip G.; Herczenik, Eszter; Maas, Coen

    2014-01-01

    Background The endocannabinoid system has previously been implicated in the regulation of neurons and inflammatory cells. Additionally, it has been reported that endocannabinoid receptors are present on circulating platelets, but there has been conflicting evidence on their contribution to platelet function. Objectives Our aim was to examine the role of endocannabinoids in platelet function in vitro and in vivo. Methods and Results We studied the effects of the well-characterized endogenous endocannabinoid anandamide on platelet aggregation in suspension, α-granule release, calcium mobilization, Syk phosphorylation, as well as platelet spreading and aggregate formation under flow. Anandamide inhibits platelet aggregation and α-granule release by collagen, collagen-derived peptide CRP-XL, ADP, arachidonic acid and thromboxane A2 analogue U46619. However, activation via thrombin receptor PAR-1 stays largely unaffected. Calcium mobilization is significantly impaired when platelets are stimulated with collagen or CRP-XL, but remains normal in the presence of the other agonists. In line with this finding, we found that anandamide prevents collagen-induced Syk phosphorylation. Furthermore, anandamide-treated platelets exhibit reduced spreading on immobilized fibrinogen, have a decreased capacity for binding fibrinogen in solution and show perturbed platelet aggregate formation under flow over collagen. Finally, we investigated the influence of Cannabis sativa consumption by human volunteers on platelet activation. Similar to our in vitro findings with anandamide, ex vivo collagen-induced platelet aggregation and aggregate formation on immobilized collagen under flow were impaired in whole blood of donors that had consumed Cannabis sativa. Conclusions Endocannabinoid receptor agonists reduce platelet activation and aggregate formation both in vitro and ex vivo after Cannabis sativa consumption. Further elucidation of this novel regulatory mechanism for platelet function

  4. Endocannabinoids control platelet activation and limit aggregate formation under flow.

    Directory of Open Access Journals (Sweden)

    Valentina De Angelis

    Full Text Available The endocannabinoid system has previously been implicated in the regulation of neurons and inflammatory cells. Additionally, it has been reported that endocannabinoid receptors are present on circulating platelets, but there has been conflicting evidence on their contribution to platelet function.Our aim was to examine the role of endocannabinoids in platelet function in vitro and in vivo.We studied the effects of the well-characterized endogenous endocannabinoid anandamide on platelet aggregation in suspension, α-granule release, calcium mobilization, Syk phosphorylation, as well as platelet spreading and aggregate formation under flow. Anandamide inhibits platelet aggregation and α-granule release by collagen, collagen-derived peptide CRP-XL, ADP, arachidonic acid and thromboxane A2 analogue U46619. However, activation via thrombin receptor PAR-1 stays largely unaffected. Calcium mobilization is significantly impaired when platelets are stimulated with collagen or CRP-XL, but remains normal in the presence of the other agonists. In line with this finding, we found that anandamide prevents collagen-induced Syk phosphorylation. Furthermore, anandamide-treated platelets exhibit reduced spreading on immobilized fibrinogen, have a decreased capacity for binding fibrinogen in solution and show perturbed platelet aggregate formation under flow over collagen. Finally, we investigated the influence of Cannabis sativa consumption by human volunteers on platelet activation. Similar to our in vitro findings with anandamide, ex vivo collagen-induced platelet aggregation and aggregate formation on immobilized collagen under flow were impaired in whole blood of donors that had consumed Cannabis sativa.Endocannabinoid receptor agonists reduce platelet activation and aggregate formation both in vitro and ex vivo after Cannabis sativa consumption. Further elucidation of this novel regulatory mechanism for platelet function may prove beneficial in the search

  5. Endocannabinoids control platelet activation and limit aggregate formation under flow.

    Science.gov (United States)

    De Angelis, Valentina; Koekman, Arnold C; Weeterings, Cees; Roest, Mark; de Groot, Philip G; Herczenik, Eszter; Maas, Coen

    2014-01-01

    The endocannabinoid system has previously been implicated in the regulation of neurons and inflammatory cells. Additionally, it has been reported that endocannabinoid receptors are present on circulating platelets, but there has been conflicting evidence on their contribution to platelet function. Our aim was to examine the role of endocannabinoids in platelet function in vitro and in vivo. We studied the effects of the well-characterized endogenous endocannabinoid anandamide on platelet aggregation in suspension, α-granule release, calcium mobilization, Syk phosphorylation, as well as platelet spreading and aggregate formation under flow. Anandamide inhibits platelet aggregation and α-granule release by collagen, collagen-derived peptide CRP-XL, ADP, arachidonic acid and thromboxane A2 analogue U46619. However, activation via thrombin receptor PAR-1 stays largely unaffected. Calcium mobilization is significantly impaired when platelets are stimulated with collagen or CRP-XL, but remains normal in the presence of the other agonists. In line with this finding, we found that anandamide prevents collagen-induced Syk phosphorylation. Furthermore, anandamide-treated platelets exhibit reduced spreading on immobilized fibrinogen, have a decreased capacity for binding fibrinogen in solution and show perturbed platelet aggregate formation under flow over collagen. Finally, we investigated the influence of Cannabis sativa consumption by human volunteers on platelet activation. Similar to our in vitro findings with anandamide, ex vivo collagen-induced platelet aggregation and aggregate formation on immobilized collagen under flow were impaired in whole blood of donors that had consumed Cannabis sativa. Endocannabinoid receptor agonists reduce platelet activation and aggregate formation both in vitro and ex vivo after Cannabis sativa consumption. Further elucidation of this novel regulatory mechanism for platelet function may prove beneficial in the search for new

  6. Numerical study on flow rate limitation of open capillary channel flow through a wedge

    Directory of Open Access Journals (Sweden)

    Ting-Ting Zhang

    2016-04-01

    Full Text Available The flow characteristics of slender-column flow in wedge-shaped channel under microgravity condition are investigated in this work. The one-dimensional theoretical model is applied to predict the critical flow rate and surface contour of stable flow. However, the one-dimensional model overestimates the critical flow rate for not considering the extra pressure loss. Then, we develop a three-dimensional simulation method with OpenFOAM, a computational fluid dynamics tool, to simulate various phenomena in wedge channels with different lengths. The numerical results are verified with the capillary channel flow experimental data on the International Space Station. We find that the three-dimensional simulation perfectly predicts the critical flow rates and surface contours under various flow conditions. Meanwhile, the general behaviors in subcritical, critical, and supercritical flow are studied in three-dimensional simulation considering variations of flow rate and open channel length. The numerical techniques for three-dimensional simulation is validated for a wide range of configurations and is hopeful to provide valuable guidance for capillary channel flow experiment and efficient liquid management in space.

  7. Klystron - Space-charge limited flow, guns, Perveance

    International Nuclear Information System (INIS)

    Isagawa, S.

    1999-01-01

    This paper treats Thermionic emission, Cathode as an e - emitter, Space-charge limited effect and 3/2 power law, Perveance, Beam spread due to space charge, Pierce guns, Magnetically immersed guns, Method of gun design including simulations, and Examples, mainly treating E3786, which attendees will operate above 1 MW-CW in a practical exercise course at KEK. (author). 74 refs

  8. Investigations on interactions between the flowing liquid lithium limiter and plasmas

    International Nuclear Information System (INIS)

    Ren, J.; Zuo, G.Z.; Hu, J.S.; Sun, Z.; Li, J.G.; Zakharov, L.E.; Ruzic, D.N.; Xu, W.Y.

    2016-01-01

    Two different designs of flowing liquid lithium limiter were first tested for power exhaust and particle removal in HT-7 in 2012 autumn campaign. During the experiments, the reliability and compatibility of the limiters within Tokamak were experimentally demonstrated, and some positive results were achieved. It was found that the flowing liquid lithium limiter was effective for suppressing H concentration and led to a low ratio of H/(H + D). O impurity was slightly decreased by using limiters as well as when using a Li coating. A significant increase of the wall retention ratio was also observed which resulted from the outstanding D particles pumping ability of flowing liquid lithium limiters. The strong interaction between plasma and lithium surface could cause lithium ejection into plasma and lead to disruptions. The stable plasmas produced by uniform Li flow were in favor of lithium control. While the limiters were applied with a uniform Li flow, the normal plasma was easy to be obtained, and the energy confinement time increased from ∼0.025 s to 0.04 s. Furthermore, it was encouraging to note that the application of flowing liquid lithium limiters could further improve the confinement of plasma by ∼10% on the basis of Li coating. These remarkable results will help for the following design of flowing liquid lithium limiter in EAST to improve the plasma operation.

  9. Regularized semiclassical limits: Linear flows with infinite Lyapunov exponents

    KAUST Repository

    Athanassoulis, Agissilaos

    2016-08-30

    Semiclassical asymptotics for Schrödinger equations with non-smooth potentials give rise to ill-posed formal semiclassical limits. These problems have attracted a lot of attention in the last few years, as a proxy for the treatment of eigenvalue crossings, i.e. general systems. It has recently been shown that the semiclassical limit for conical singularities is in fact well-posed, as long as the Wigner measure (WM) stays away from singular saddle points. In this work we develop a family of refined semiclassical estimates, and use them to derive regularized transport equations for saddle points with infinite Lyapunov exponents, extending the aforementioned recent results. In the process we answer a related question posed by P.L. Lions and T. Paul in 1993. If we consider more singular potentials, our rigorous estimates break down. To investigate whether conical saddle points, such as -|x|, admit a regularized transport asymptotic approximation, we employ a numerical solver based on posteriori error control. Thus rigorous upper bounds for the asymptotic error in concrete problems are generated. In particular, specific phenomena which render invalid any regularized transport for -|x| are identified and quantified. In that sense our rigorous results are sharp. Finally, we use our findings to formulate a precise conjecture for the condition under which conical saddle points admit a regularized transport solution for the WM. © 2016 International Press.

  10. High frequency components of tracheal sound are emphasized during prolonged flow limitation

    International Nuclear Information System (INIS)

    Tenhunen, M; Huupponen, E; Saastamoinen, A; Kulkas, A; Himanen, S-L; Rauhala, E

    2009-01-01

    A nasal pressure transducer, which is used to study nocturnal airflow, also provides information about the inspiratory flow waveform. A round flow shape is presented during normal breathing. A flattened, non-round shape is found during hypopneas and it can also appear in prolonged episodes. The significance of this prolonged flow limitation is still not established. A tracheal sound spectrum has been analyzed further in order to achieve additional information about breathing during sleep. Increased sound frequencies over 500 Hz have been connected to obstruction of the upper airway. The aim of the present study was to examine the tracheal sound signal content of prolonged flow limitation and to find out whether prolonged flow limitation would consist of abundant high frequency activity. Sleep recordings of 36 consecutive patients were examined. The tracheal sound spectral analysis was performed on 10 min episodes of prolonged flow limitation, normal breathing and periodic apnea-hypopnea breathing. The highest total spectral amplitude, implicating loudest sounds, occurred during flow-limited breathing which also presented loudest sounds in all frequency bands above 100 Hz. In addition, the tracheal sound signal during flow-limited breathing constituted proportionally more high frequency activities compared to normal breathing and even periodic apnea-hypopnea breathing

  11. COUNTERCURRENT FLOW LIMITATION EXPERIMENTS AND MODELING FOR IMPROVED REACTOR SAFETY

    International Nuclear Information System (INIS)

    Vierow, Karen

    2008-01-01

    This project is investigating countercurrent flow and 'flooding' phenomena in light water reactor systems to improve reactor safety of current and future reactors. To better understand the occurrence of flooding in the surge line geometry of a PWR, two experimental programs were performed. In the first, a test facility with an acrylic test section provided visual data on flooding for air-water systems in large diameter tubes. This test section also allowed for development of techniques to form an annular liquid film along the inner surface of the 'surge line' and other techniques which would be difficult to verify in an opaque test section. Based on experiences in the air-water testing and the improved understanding of flooding phenomena, two series of tests were conducted in a large-diameter, stainless steel test section. Air-water test results and steam-water test results were directly compared to note the effect of condensation. Results indicate that, as for smaller diameter tubes, the flooding phenomena is predominantly driven by the hydrodynamics. Tests with the test sections inclined were attempted but the annular film was easily disrupted. A theoretical model for steam venting from inclined tubes is proposed herein and validated against air-water data. Empirical correlations were proposed for air-water and steam-water data. Methods for developing analytical models of the air-water and steam-water systems are discussed, as is the applicability of the current data to the surge line conditions. This report documents the project results from July 1, 2005 through June 30, 2008

  12. COUNTERCURRENT FLOW LIMITATION EXPERIMENTS AND MODELING FOR IMPROVED REACTOR SAFETY

    Energy Technology Data Exchange (ETDEWEB)

    Vierow, Karen

    2008-09-26

    This project is investigating countercurrent flow and “flooding” phenomena in light water reactor systems to improve reactor safety of current and future reactors. To better understand the occurrence of flooding in the surge line geometry of a PWR, two experimental programs were performed. In the first, a test facility with an acrylic test section provided visual data on flooding for air-water systems in large diameter tubes. This test section also allowed for development of techniques to form an annular liquid film along the inner surface of the “surge line” and other techniques which would be difficult to verify in an opaque test section. Based on experiences in the air-water testing and the improved understanding of flooding phenomena, two series of tests were conducted in a large-diameter, stainless steel test section. Air-water test results and steam-water test results were directly compared to note the effect of condensation. Results indicate that, as for smaller diameter tubes, the flooding phenomena is predominantly driven by the hydrodynamics. Tests with the test sections inclined were attempted but the annular film was easily disrupted. A theoretical model for steam venting from inclined tubes is proposed herein and validated against air-water data. Empirical correlations were proposed for air-water and steam-water data. Methods for developing analytical models of the air-water and steam-water systems are discussed, as is the applicability of the current data to the surge line conditions. This report documents the project results from July 1, 2005 through June 30, 2008.

  13. Measurements of exhaled nitric oxide with the single-breath technique and positive expiratory pressure in infants.

    Science.gov (United States)

    Wildhaber, J H; Hall, G L; Stick, S M

    1999-01-01

    The aim of this study was to adapt the single-breath technique with positive expiratory pressure to measure exhaled nitric oxide (eNO) in infants. We hypothesized that exhaled eNO was greater in wheezy than in healthy infants. We studied 30 infants (16 wheezy and 14 healthy). The forced expiratory volume in 0.5 s (FEV0.5) was determined with the raised volume rapid thoracic compression technique, and eNO was measured during constant expiratory flow with a rapid-response chemiluminescence analyzer. After passive inflation to a preset pressure of 20 cm H2O, thoracic compression with an inflatable jacket caused forced expiration to occur through a face-mask with an expiratory flow resistor attached. During the forced expiration, the jacket pressure was increased to maintain a constant driving mouth pressure and hence a constant expiratory flow (50 ml/s). The mean level of eNO in the wheezy infants (31.8 ppb) was significantly higher than the level in healthy infants (18.8 ppb) (p = 0.03). A family history of atopy in parents was associated with increased eNO levels (p history of atopy.

  14. Limits to ductility set by plastic flow localization

    International Nuclear Information System (INIS)

    Needleman, A.; Rice, J.R.

    1977-11-01

    The theory of strain localization is reviewed with reference both to local necking in sheet metal forming processes and to more general three dimensional shear band localizations that sometimes mark the onset of ductile rupture. Both bifurcation behavior and the growth of initial imperfections are considered. In addition to analyses based on classical Mises-like constitutive laws, approaches to localization based on constitutive models that may more accurately model processes of slip and progressive rupturing on the microscale in structural alloys are discussed. Among these non-classical constitutive features are the destabilizing roles of yield surface vertices and of non-normality effects, arising, for example, from slight pressure sensitivity of yield. Analyses based on a constitutive model of a progressively cavitating dilational plastic material which is intended to model the process of ductile void growth in metals are also discussed. A variety of numerical results are presented. In the context of the three dimensional theory of localization, it is shown that a simple vertex model predicts ratios of ductility in plane strain tension to ductility in axisymmetric tension qualitatively consistent with experiment, and the destabilizing influence of a hydrostatic stress dependent void nucleation criterion is illustrated. In the sheet necking context, and focussing on positive biaxial stretching, it is shown that forming limit curves based on a simple vertex model and those based on a simple void growth model are qualitatively in accord, although attributing instability to very different physical mechanisms. These forming limit curves are compared with those obtained from the Mises material model and employing various material and geometric imperfections

  15. Expiratory muscle control during vomiting - Role of brain stem expiratory neurons

    Science.gov (United States)

    Miller, A. D.; Tan, L. K.

    1987-01-01

    The neural mechanisms controlling the muscles involved during vomiting were examined using decerebrated cats. In one experiment, the activity of the ventral respiratory group (VRG) expiratory (E) neurons was recorded during induced 'fictive vomiting' (i.e., a series of bursts of coactivation of abdominal and phrenic nerves that would be expected to produce expulsion in unparalyzed animals) and vomiting. In a second, abdominal muscle electromyographic and nerve activity were compared before and after sectioning the axons of descending VRG E neurons as they cross the midline between C1 and the obex (the procedure that is known to abolish expiratory modulation of internal intercostal muscle activity). The results of the study indicate that the abdominal muscles are controlled differently during respiration and vomiting.

  16. Melt Flow and Energy Limitation of Laser Cutting

    Directory of Open Access Journals (Sweden)

    Pavel Hudeček

    2016-01-01

    Full Text Available Laser technology is a convertible technology for plenty of parts in most materials. Laser material processing for industrial manufacturing applications is today a widespread procedure for welding, cutting, marking and micro machining of metal and plastic parts and components. Involvement and support this huge mass-production industry of laser cutting, new technology and dry-process using lasers were and are being actively developed. Fundamentally, industrial laser cutting or other applications on industry should satisfy the four key practical application issues including “Quality or Performance”, “Throughput or Speed”, “Cost or Total Ownership Cost”, and “Reliability”. Laser requires for examples several complicated physical factors to be resolved including die strength to be enable good wire-bonding and survival of severe cycling test, clean cutting wall surface, good cutting of direct attach film, and proper speed of cutting for achieving economy of throughput. Some example of maximum cutting rate, wherewith is normally limited laser energy, cutting speed is depend on type laser, different of cutting with one laser beam and beam pattern and applied laser power/material thickness will be introduced in this paper.

  17. Effect of Training Frequency on Maximum Expiratory Pressure

    Science.gov (United States)

    Anand, Supraja; El-Bashiti, Nour; Sapienza, Christine

    2012-01-01

    Purpose: To determine the effects of expiratory muscle strength training (EMST) frequency on maximum expiratory pressure (MEP). Method: We assigned 12 healthy participants to 2 groups of training frequency (3 days per week and 5 days per week). They completed a 4-week training program on an EMST trainer (Aspire Products, LLC). MEP was the primary…

  18. Expiratory Snoring Predicts Obstructive Pulmonary Disease in Patients with Sleep-disordered Breathing.

    Science.gov (United States)

    Alchakaki, Abdulrazak; Riehani, Anas; Shikh-Hamdon, Mulham; Mina, Nader; Badr, M Safwan; Sankari, Abdulghani

    2016-01-01

    Sleep-disordered breathing and chronic obstructive pulmonary disease are two common conditions that may present concomitantly. The effects of chronic obstructive pulmonary disease on the polysomnographic manifestation of sleep-disordered breathing have not been studied. We hypothesized that the presence of airflow obstruction could be predicted by the presence of expiratory upper airway narrowing during sleep in patients with sleep-disordered breathing. Ninety-three patients with sleep-disordered breathing (19 men; age, 51.6 yr; body mass index, 40.1 kg/m(2); apnea-hypopnea index, 37.4 events/h) were observed. Every patient had an in-lab polysomnography study and complete pulmonary function tests. Sleep and respiratory events were scored using American Academy of Sleep Medicine recommended scoring criteria. Expiratory snoring events were identified on polysomnography using microphone sensor and/or pressure flow sensor in each patient. The FEV1/FVC ratio less than 70 was used to define the presence of airflow obstruction. The proportion analysis demonstrated that patients with expiratory snoring have 11 times higher odds of having evidence of lower airway obstruction, defined as FEV1/FVC less than 70 (odds ratio [OR], 11.03; P snoring, smoking, 3% oxygen desaturation index, 2% oxygen desaturation index, and age (P snoring and smoking (OR, 11.76; confidence interval, 3.23-42.83; and OR, 9.95; confidence interval, 2.67-37.09), respectively. The multiple linear regression analysis revealed that the linear combination of mean SaO2 and expiratory snoring (P snoring predicts obstructive airway disorders. Patients with expiratory snoring and low mean oxygen saturation during sleep should be carefully assessed for pulmonary disorders such as asthma and chronic obstructive pulmonary disease.

  19. Numerical study on modeling of liquid film flow under countercurrent flow limitation in volume of fluid method

    Energy Technology Data Exchange (ETDEWEB)

    Watanabe, Taro, E-mail: watanabe_t@qe.see.eng.osaka-u.ac.jp [Graduate School of Engineering, Osaka University, 2-1, Yamadaoka, Suita-shi, Osaka 565-7895 (Japan); Takata, Takashi, E-mail: takata.takashi@jaea.go.jp [Japan Atomic Energy Agency, 4002 Narita-chou, Oarai-machi, Higashi-Ibaraki-gun, Ibaraki 331-1393 (Japan); Yamaguchi, Akira, E-mail: yamaguchi@n.t.u-tokyo.ac.jp [Graduate School of Engineering, The University of Tokyo, 2-22 Shirakata-Shirane, Tokai-mura, Naka-gun, Ibaraki 319-1188 (Japan)

    2017-03-15

    Highlights: • Thin liquid film flow under CCFL was modeled and coupled with the VOF method. • The difference of the liquid flow rate in experiments of CCFL was evaluated. • The proposed VOF method can quantitatively predict CCFL with low computational cost. - Abstract: Countercurrent flow limitation (CCFL) in a heat transfer tube at a steam generator (SG) of pressurized water reactor (PWR) is one of the important issues on the core cooling under a loss of coolant accident (LOCA). In order to improve the prediction accuracy of the CCFL characteristics in numerical simulations using the volume of fluid (VOF) method with less computational cost, a thin liquid film flow in a countercurrent flow is modeled independently and is coupled with the VOF method. The CCFL characteristics is evaluated analytically in condition of a maximizing down-flow rate as a function of a void fraction or a liquid film thickness considering a critical thickness. Then, we have carried out numerical simulations of a countercurrent flow in a vertical tube so as to investigate the CCFL characteristics and compare them with the previous experimental results. As a result, it has been concluded that the effect of liquid film entrainment by upward gas flux will cause the difference in the experiments.

  20. Correlation Between Abdominal Muscle Thickness and Maximal Expiratory Pressure.

    Science.gov (United States)

    Ishida, Hiroshi; Suehiro, Tadanobu; Kurozumi, Chiharu; Ono, Koji; Watanabe, Susumu

    2015-11-01

    The activity of abdominal muscles mainly produces high expiratory pressure. These include the rectus abdominis, external oblique, internal oblique, and transverse abdominis muscles. The purpose of this study was to determine whether maximal expiratory pressure is associated with each abdominal muscle thickness at rest. Thirty-nine healthy male volunteers (mean age ± SD, 20.7 ± 2.7 years) participated in the study. The thickness of the right rectus abdominis, external oblique, internal oblique, and transverse abdominis muscles was measured by B-mode sonography in the supine position. The maximal expiratory pressure was obtained with a spirometer in the sitting position. The correlations between each abdominal muscle thickness and maximal expiratory pressure were determined by the Pearson correlation coefficient. The correlation coefficient between the rectus abdominis muscle and maximal expiratory pressure was 0.571 (Pmuscles and maximal expiratory pressure were 0.297 (P = .066), 0.267 (P = .100), and 0.022 (P = .894), respectively. Our results indicate that the rectus abdominis muscle thickness might be more highly correlated with expiratory pressure production than the external oblique, internal oblique, and transverse abdominis muscle thickness. © 2015 by the American Institute of Ultrasound in Medicine.

  1. Barriers to the Flow of Technical Information: Limitation Statements - Legal Basis.

    Science.gov (United States)

    Downie, Currie S.

    The new "Freedom of Information Act" and the more important reasons for limitations on the flow of information are discussed. The legal basis for these limitations can be found in the almost 100 statutory provisions which prohibit, exempt, or otherwise protect certain types of information from disclosure. The Export Control Acts of the Department…

  2. Effect of tube size and obstacles on explosion limits in flowing gases.

    NARCIS (Netherlands)

    Bolk, Jeroen W.; Bolk, J.W.; Westerterp, K.R.

    1999-01-01

    In a large pilot plant the upper explosion limit of ethene-air-nitrogen mixtures was experimented in 3.0-m-long and 21-, 50-, and 100-mm-dia. tubes at different flow rates, pressures, and temperatures. The upper explosion limit, influenced by the gas velocity, becomes smaller and shifts to higher

  3. [Study of personal best value of peak expiratory flow in patients with asthma--comparison of the highest value of daily PEF under good control and the highest value of daily PEF obtained after using repeated inhaled beta2-agonist during high-dose inhaled steroid treatment].

    Science.gov (United States)

    Watanabe, Naoto; Makino, Sohei; Kihara, Norio; Fukuda, Takeshi

    2008-12-01

    In the guideline for asthma management, it is important to find the personal best value of peak expiratory flow (best PEF). Recently, we have substituted the highest value of PEF in daily life under good control (daily highest PEF) for the best PEF. In the present study, we considered whether the daily highest PEF could be used as the best PEF or not. Subjects were 30 asthmatics who were well controlled but whose baseline PEF values were less than 80 percent of predicted values. We compared the daily highest PEF and the highest of PEF obtained after repeated inhaled beta2-agonist (salbutamol MDI every 20 minutes three times). All subjects then received 1600 microg/day of beclomethasone dipropionate (BDP) for 4 to 8 weeks. We studied the effect of high-dose inhaled steroid treatment on each PEF value and compared the daily highest PEF and the highest PEF obtained after using repeated salbutamol MDI during high dose inhaled steroid therapy on the examination day again. The baseline PEF, daily highest PEF and the highest PEF obtained after salbutamol MDI were significantly less than the each values obtained after high-dose BDP. The best PEF value of them was the value obtained after repeated salbutamol MDI during high dose BDP. We suggest that the daily highest PEF under good control is not a substitute for best PEF because it changes according to the degree of improvement of airway inflammation. We recommend that a course of high dose inhaled steroid is effective in finding the best value of PEF for each individual with moderate asthma.

  4. Comparison of forced expiratory spirometric flow changes following ...

    African Journals Online (AJOL)

    Group B received intrathecal anaesthesia 15 mgs of bupivacaine with 0.5 ml of normal saline and Group BF received 15 mgs of bupivacaine with 0.5 ml of fentanyl (25 μg) intrathecally. The patients were instructed about the performance of the spirometry on the previous evening of the surgery. Forced vital capacity, forced ...

  5. Reference population equations using peak expiratory flow meters ...

    African Journals Online (AJOL)

    Many formulae for predicting lung function values for Nigerians have been produced by a lot of investigators. The same principle but different statistical methods were adopted by different authors in generating these equations, hence the variability observed among these formulae. Most equations in current use are based on ...

  6. Changes in Peak Expiratory Flow Rate, Blood Pressure

    African Journals Online (AJOL)

    FinePrint

    2010-03-23

    Mar 23, 2010 ... There are many compounds in coffee that are often thought to have implications upon human health; these include. Caffeine, Micronutrients, LDL. Cholesterols and Chlorogenic acid. The major physiologically active substance in coffee is the alkaloid caffeine. (C H O N .H O), also called guaranine or. 8. 10.

  7. 16 reference population equations using peak expiratory flow meters

    African Journals Online (AJOL)

    DR. AMINU

    Department of Human Physiology Faculty of Medicine, Bayero University, Kano. ABSTRACT. Many formulae for predicting lung function values for Nigerians have been produced by a lot of investigators. The same principle but different statistical methods were adopted by different authors in generating these equations, ...

  8. factors influencing peak expiratory flow in teenage boys

    African Journals Online (AJOL)

    physically demanding the activity was deemed to be by the authors. (A value of 1 (least demanding) was assigned to goU, 2 to cricket, table tennis and hiking, 3 to tennis, gym, waterpolo, basketball, running, cycling, soccer, ice-skating and surfing, 4 to athletics, hockey, squash, karate, kung-fu and swimming, and 5 to rugby.).

  9. Factors influencing peak expiratory flow in teenage boys | van ...

    African Journals Online (AJOL)

    To establish PEF values for teenage boys in a Cape Town suburb and examine factors that possibly influence this measurement. Setting. A high school for boys in the southern suburbs of CapeTown. Methods. Measurements of PEF were taken for 124 boys. Subjects were approximately 16 years old and apparently healthy ...

  10. Overcoming Information Limitations for the Prescription of an Environmental Flow Regime for a Central American River

    Directory of Open Access Journals (Sweden)

    Peter C. Esselman

    2010-03-01

    Full Text Available Hydropower dam construction is expanding rapidly in Central America because of the increasing demand for electricity. Although hydropower can provide a low-carbon source of energy, dams can also degrade socially valued riverine and riparian ecosystems and the services they provide. Such degradation can be partially mitigated by the release of environmental flows below dams. However, environmental flows have been applied infrequently to dams in Central America, partly because of the lack of information on the ecological, social, and economic aspects of rivers. This paper presents a case study of how resource and information limitations were addressed in the development of environmental flow recommendations for the Patuca River in Honduras below a proposed hydroelectric dam. To develop flow recommendations, we applied a multistep process that included hydrological analysis and modeling, the collection of traditional ecological knowledge (TEK during field trips, expert consultation, and environmental flow workshops for scientists, water managers, and community members. The final environmental flow recommendation specifies flow ranges for different components of river hydrology, including low flows for each month, high-flow pulses, and floods, in dry, normal, and wet years. The TEK collected from local and indigenous riverine communities was particularly important for forming hypotheses about flow-dependent ecological and social factors that may be vulnerable to disruption from dam-modified river flows. We show that our recommended environmental flows would have a minimal impact on the dam's potential to generate electricity. In light of rapid hydropower development in Central America, we suggest that environmental flows are important at the local scale, but that an integrated landscape perspective is ultimately needed to pursue hydropower development in a manner that is as ecologically sustainable as possible.

  11. Flow motifs reveal limitations of the static framework to represent human interactions

    Science.gov (United States)

    Rocha, Luis E. C.; Blondel, Vincent D.

    2013-04-01

    Networks are commonly used to define underlying interaction structures where infections, information, or other quantities may spread. Although the standard approach has been to aggregate all links into a static structure, some studies have shown that the time order in which the links are established may alter the dynamics of spreading. In this paper, we study the impact of the time ordering in the limits of flow on various empirical temporal networks. By using a random walk dynamics, we estimate the flow on links and convert the original undirected network (temporal and static) into a directed flow network. We then introduce the concept of flow motifs and quantify the divergence in the representativity of motifs when using the temporal and static frameworks. We find that the regularity of contacts and persistence of vertices (common in email communication and face-to-face interactions) result on little differences in the limits of flow for both frameworks. On the other hand, in the case of communication within a dating site and of a sexual network, the flow between vertices changes significantly in the temporal framework such that the static approximation poorly represents the structure of contacts. We have also observed that cliques with 3 and 4 vertices containing only low-flow links are more represented than the same cliques with all high-flow links. The representativity of these low-flow cliques is higher in the temporal framework. Our results suggest that the flow between vertices connected in cliques depend on the topological context in which they are placed and in the time sequence in which the links are established. The structure of the clique alone does not completely characterize the potential of flow between the vertices.

  12. Estimation of expiratory time constants via fuzzy clustering

    NARCIS (Netherlands)

    M.S. Lourens (M.S.); L. Ali (Lejla); B.W. van den Berg (Bart); A.F.M. Verbraak (Anton); J.M. Bogaard (Jan); H.C. Hoogsteden (Henk); R. Babuška (R.)

    2001-01-01

    markdownabstractObjective. In mechanically ventilated patients the expiratorytime constant provides information about respiratory mechanics. In thepresent study a new method, fuzzy clustering, is proposed to determine expiratory time constants. Fuzzy clustering differs from other methods since it

  13. The evolution of sensory divergence in the context of limited gene flow in the bumblebee bat.

    Science.gov (United States)

    Puechmaille, Sébastien J; Gouilh, Meriadeg Ar; Piyapan, Piyathip; Yokubol, Medhi; Mie, Khin Mie; Bates, Paul J; Satasook, Chutamas; Nwe, Tin; Bu, Si Si Hla; Mackie, Iain J; Petit, Eric J; Teeling, Emma C

    2011-12-06

    The sensory drive theory of speciation predicts that populations of the same species inhabiting different environments can differ in sensory traits, and that this sensory difference can ultimately drive speciation. However, even in the best-known examples of sensory ecology driven speciation, it is uncertain whether the variation in sensory traits is the cause or the consequence of a reduction in levels of gene flow. Here we show strong genetic differentiation, no gene flow and large echolocation differences between the allopatric Myanmar and Thai populations of the world's smallest mammal, Craseonycteris thonglongyai, and suggest that geographic isolation most likely preceded sensory divergence. Within the geographically continuous Thai population, we show that geographic distance has a primary role in limiting gene flow rather than echolocation divergence. In line with sensory-driven speciation models, we suggest that in C. thonglongyai, limited gene flow creates the suitable conditions that favour the evolution of sensory divergence via local adaptation.

  14. Evaluation and limitations of standard wall functions in channel and step flow configurations

    OpenAIRE

    Stanković, B.; Stojanović, A.; Sijerčić, M.; Belošević, S.; Čantrak, S.

    2014-01-01

    This paper reviews and investigates the implementation, evaluation and limitations of conventional wall functions, based on law of the wall, in combination with linear k   turbulence model in simple (fully developed channel) and complex (backward facing step) flow configurations. The near-wall viscosity-affected layer of a turbulent fluid flow poses a number of challenges, from both modeling and numerical viewpoints. Over this thin wall-adjacent region turbulence properties change orders of...

  15. The limit of the Yang-Mills-Higgs flow on Higgs bundles

    OpenAIRE

    Li, Jiayu; Zhang, Xi

    2014-01-01

    In this paper, we consider the gradient flow of the Yang-Mills-Higgs functional for Higgs pairs on a Hermitian vector bundle $(E, H_{0})$ over a compact K\\"ahler manifold $(M, \\omega )$. We study the asymptotic behavior of the Yang-Mills-Higgs flow for Higgs pairs at infinity, and show that the limiting Higgs sheaf is isomorphic to the double dual of the graded Higgs sheaves associated to the Harder-Narasimhan-Seshadri filtration of the initial Higgs bundle.

  16. Feasibility study of respiratory questionnaire and peak flow recordings in autobody shop workers exposed to isocyanate-containing spray paint: observations and limitations.

    Science.gov (United States)

    Cullen, M R; Redlich, C A; Beckett, W S; Weltmann, B; Sparer, J; Jackson, G; Ruff, T; Rubinstein, E; Holden, W

    1996-06-01

    Diisocyanates, highly reactive monomers which cross-link polyurethane, are the most widely recognized causes of occupational asthma. Many exposed workers are end-users, including autobody spray painters who form a large population at risk. Neither the factors which determine incidence rate nor strategies for control have been adequately studied in this setting. We have conducted a cross-sectional survey of 23 (about one in five) autobody shops in the New Haven area to determine the feasibility of clinical epidemiological studies in this population. Among 102 workers, there was a high rate of airway symptoms consistent with occupational asthma (19.6%). Symptoms were most prevalent among those with the greatest opportunity for exposure (dedicated spray painters) and least among office workers; part-time painters had intermediate rates. Atopy was not associated with risk while smoking seemed to correlate with symptoms. Regular use of air-supplied respirators appeared to be associated with lower risk among workers who painted part- or full-time. We were unable to validate the questionnaire responses with peak expiratory flow record data attempted on a 1/3 sample of the workers. Despite intensive training and effort, subject compliance was limited. Among those who provided adequate data (24 of 38), only two demonstrated unequivocal evidence of labile airways; two others demonstrated lesser changes consistent with an occupational effect on flow rates. There was no clear association between these findings and either questionnaire responses or exposure classification. Overall, the survey suggests that there is a high prevalence of airway symptoms among workers in autobody shops, at least in part due to work-related asthma. However, there is need for both methodological and substantive research in this setting to document rates of occupational asthma and to develop a scientific basis for its effective control.

  17. The ω-limit sets of a flow and periodic orbits

    International Nuclear Information System (INIS)

    Wang Xiaoxia; Blackmore, Denis; Wang Chengwen

    2009-01-01

    In this paper we discuss the ω-limit sets of a flow using the Conley theory, chain recurrence and Morse decompositions. Our results generalize and improve the related result in [Schropp J. A reduction principle for ω-limit sets. Z Angew Math Meth 1996;76(6):349-56], and we also show how they can be used as a basis for some new criteria for the existence of periodic orbits.

  18. Impact of humidification and nebulization during expiratory limb protection: an experimental bench study.

    Science.gov (United States)

    Tonnelier, Alexandre; Lellouche, François; Bouchard, Pierre Alexandre; L'Her, Erwan

    2013-08-01

    Different filtering devices are used during mechanical ventilation to avoid dysfunction of flow and pressure transducers or for airborne microorganisms containment. Water condensates, resulting from the use of humidifiers, but also residual nebulization particles may have a major influence on expiratory limb resistance. To evaluate the influence of nebulization and active humidification on the resistance of expiratory filters. A respiratory system analog was constructed using a test lung, an ICU ventilator, heated humidifiers, and a piezoelectric nebulizer. Humidifiers were connected to different types of circuits (unheated, mono-heated, new-generation and old-generation bi-heated). Five filter types were evaluated: electrostatic, heat-and-moisture exchanger, standard, specific, and internal heated high-efficiency particulate air [HEPA] filter. Baseline characteristics were obtained from each dry filter. Differential pressure measurements were carried out after 24 hours of continuous in vitro use for each condition, and after 24 hours of use with an old-generation bi-heated circuit without nebulization. While using unheated circuits, measurements had to be interrupted before 24 hours for all the filtering devices except the internal heated HEPA filter. The heat-and-moisture exchangers occluded before 24 hours with the unheated and mono-heated circuits. The circuit type, nebulization practice, and duration of use did not influence the internal heated HEPA filter resistance. Expiratory limb filtration is likely to induce several major adverse events. Expiratory filter resistance increase is due mainly to the humidification circuit type, rather than to nebulization. If filtration is mandatory while using an unheated circuit, a dedicated filter should be used for ≤ 24 hours, or a heated HEPA for a longer duration.

  19. Maximal hysteresis: a new method to set positive end-expiratory pressure in acute lung injury?

    Science.gov (United States)

    Koefoed-Nielsen, J; Andersen, G; Barklin, A; Bach, A; Lunde, S; Tønnesen, E; Larsson, A

    2008-05-01

    No methods are superior when setting positive end-expiratory pressure (PEEP) in acute lung injury (ALI). In ALI, the vertical distance (hysteresis) between the inspiratory and expiratory limbs of a static pressure-volume (PV) loop mainly indicates lung recruitment. We hypothesized that PEEP set at the pressure where hysteresis is 90% of its maximum (90%MH) would give similar oxygenation, but less cardiovascular depression than PEEP set at the pressure at lower inflection point (LIP) on the inspiratory limb or at the point of maximal curvature (PMC) on the expiratory limb in ALI. In 12 mechanically ventilated pigs, ALI was induced in a randomized fashion by lung lavage, lung lavage plus injurious ventilation, or by oleic acid. From a static PV loop obtained by an interrupted low-flow method, the pressures at LIP [25 (25, 25) cmH(2)O, mean and 25, 75 percentiles], at PMC [24 (20, 24) cmH(2)O], and at 90% MH [19 (18, 19) cmH(2)O] were determined and used for the PEEP-settings. We measured lung inflation (by computed tomography), end-expiratory lung volume (EELV), airway pressures, compliance of the respiratory system (Crs), blood gases, cardiac output and arterial blood pressure. There were no differences between the PEEP settings in EELV or oxygenation, but the 90%MH setting gave lower end-inspiratory pause pressure (P<0.025), higher Crs (P<0.025), less hyper-aeration (P<0.025) and better maintained hemodynamics. In this porcine lung injury model, PEEP set at 90% MH gave better lung mechanics and hemodynamics, than PEEP set at PMC or LIP.

  20. Chest physiotherapy using passive expiratory techniques does not reduce bronchiolitis severity: a randomised controlled trial.

    Science.gov (United States)

    Rochat, Isabelle; Leis, Patricia; Bouchardy, Marie; Oberli, Christine; Sourial, Hendrika; Friedli-Burri, Margrit; Perneger, Thomas; Barazzone Argiroffo, Constance

    2012-03-01

    Chest physiotherapy (CP) using passive expiratory manoeuvres is widely used in Western Europe for the treatment of bronchiolitis, despite lacking evidence for its efficacy. We undertook an open randomised trial to evaluate the effectiveness of CP in infants hospitalised for bronchiolitis by comparing the time to clinical stability, the daily improvement of a severity score and the occurrence of complications between patients with and without CP. Children bronchiolitis in a tertiary hospital during two consecutive respiratory syncytial virus seasons were randomised to group 1 with CP (prolonged slow expiratory technique, slow accelerated expiratory flow, rarely induced cough) or group 2 without CP. All children received standard care (rhinopharyngeal suctioning, minimal handling, oxygen for saturation ≥92%, fractionated meals). Ninety-nine eligible children (mean age, 3.9 months), 50 in group 1 and 49 in group 2, with similar baseline variables and clinical severity at admission. Time to clinical stability, assessed as primary outcome, was similar for both groups (2.9 ± 2.1 vs. 3.2 ± 2.8 days, P = 0.45). The rate of improvement of a clinical and respiratory score, defined as secondary outcome, only showed a slightly faster improvement of the respiratory score in the intervention group when including stethoacoustic properties (P = 0.044). Complications were rare but occurred more frequently, although not significantly (P = 0.21), in the control arm. In conclusion, this study shows the absence of effectiveness of CP using passive expiratory techniques in infants hospitalised for bronchiolitis. It seems justified to recommend against the routine use of CP in these patients.

  1. Amplified fragment length polymorphism fingerprints support limited gene flow among social spider populations

    NARCIS (Netherlands)

    Smith, Deborah; van Rijn, Sander; Henschel, Joh; Bilde, Trine; Lubin, Yael

    We used DNA fingerprints to determine whether the population structure and colony composition of the cooperative social spider Stegodyphus dumicola are compatible with requirements of interdemic ('group') selection: differential proliferation of demes or groups and limited gene flow among groups. To

  2. The lower limit of the flowing pore throat radius in the extra-low permeability reservoir

    Science.gov (United States)

    Xiang, Junhui; Yin, Daiyin

    2018-02-01

    In this paper, a method for determining the lower limit of flowing pore throat radius of the extra low permeability reservoir in the periphery of Changyuan Oil Fields is given. The capillary pressure curve is divided into linear type and concave type. The nuclear magnetic resonance (NMR) T2 spectrum is divided into 3 types: the left peak is greater than the right peak, the left peak is equal to the right one, and the left peak is smaller than the right one. The method for determining the lower limit of flowing pore throat radius is, first, converting the nuclear magnetic resonance T2 spectrum to the capillary pressure curve calculated, then fitting the capillary pressure curves measured by the constant speed mercury injection experiment and the capillary pressure curve calculated. After finding the relevant parameters, converting the horizontal axis of the NMR T2 spectra from relaxation time to pore throat radius, and the pore throat radius corresponding to the T2 cutoff value is the lower limit of the flowing pore throat radius. The lower limit of the flowing pore throat radius of the extra low permeability Fuyang Oil Reservoir in the periphery of Changyuan Oil Fields is about 0.68μm

  3. How to identify the speed limiting factor of a TCP flow

    NARCIS (Netherlands)

    Timmer, Mark

    2005-01-01

    This thesis develops a method for identifying the speed limiting factor of a TCP flow. Five factors are considered: the receive window, the send buffer, the network and two kinds of application layer factors. Criteria for recognizing each factor based on TCP header information are put forward. These

  4. On singular limits arising in the scale analysis of stratified fluid flows

    Czech Academy of Sciences Publication Activity Database

    Feireisl, Eduard; Klein, R.; Novotný, A.; Zatorska, E.

    2016-01-01

    Roč. 26, č. 3 (2016), s. 419-443 ISSN 0218-2025 Grant - others:European Research Council(XE) MATHEF(320078) Institutional support: RVO:67985840 Keywords : isentropic fluid flow * strong stratification * singular limit * anelastic approximation Subject RIV: BA - General Mathematics Impact factor: 2.860, year: 2016 http://www.worldscientific.com/doi/10.1142/S021820251650007X

  5. Detection of alloreactive T cells by flow cytometry : A new test compared with limiting dilution assay

    NARCIS (Netherlands)

    de Haan, A; van der Gun, [No Value; van der Bij, W; de Leij, LFMH; Prop, J

    2002-01-01

    Background. Frequencies of alloreactive T cells determined by limiting dilution assays (LDA) may not adequately reflect the donor-reactive immune status in transplant recipients. To reevaluate LDA frequencies, we developed a flow cytometry test for direct determination of alloreactive T-cell

  6. Comparison of changes in tidal volume associated with expiratory rib cage compression and expiratory abdominal compression in patients on prolonged mechanical ventilation

    OpenAIRE

    Morino, Akira; Shida, Masahiro; Tanaka, Masashi; Sato, Kimihiro; Seko, Toshiaki; Ito, Shunsuke; Ogawa, Shunichi; Takahashi, Naoaki

    2015-01-01

    [Purpose] This study was designed to compare and clarify the relationship between expiratory rib cage compression and expiratory abdominal compression in patients on prolonged mechanical ventilation, with a focus on tidal volume. [Subjects and Methods] The subjects were 18 patients on prolonged mechanical ventilation, who had undergone tracheostomy. Each patient received expiratory rib cage compression and expiratory abdominal compression; the order of implementation was randomized. Subjects ...

  7. Comparison of changes in tidal volume associated with expiratory rib cage compression and expiratory abdominal compression in patients on prolonged mechanical ventilation.

    Science.gov (United States)

    Morino, Akira; Shida, Masahiro; Tanaka, Masashi; Sato, Kimihiro; Seko, Toshiaki; Ito, Shunsuke; Ogawa, Shunichi; Takahashi, Naoaki

    2015-07-01

    [Purpose] This study was designed to compare and clarify the relationship between expiratory rib cage compression and expiratory abdominal compression in patients on prolonged mechanical ventilation, with a focus on tidal volume. [Subjects and Methods] The subjects were 18 patients on prolonged mechanical ventilation, who had undergone tracheostomy. Each patient received expiratory rib cage compression and expiratory abdominal compression; the order of implementation was randomized. Subjects were positioned in a 30° lateral recumbent position, and a 2-kgf compression was applied. For expiratory rib cage compression, the rib cage was compressed unilaterally; for expiratory abdominal compression, the area directly above the navel was compressed. Tidal volume values were the actual measured values divided by body weight. [Results] Tidal volume values were as follows: at rest, 7.2 ± 1.7 mL/kg; during expiratory rib cage compression, 8.3 ± 2.1 mL/kg; during expiratory abdominal compression, 9.1 ± 2.2 mL/kg. There was a significant difference between the tidal volume during expiratory abdominal compression and that at rest. The tidal volume in expiratory rib cage compression was strongly correlated with that in expiratory abdominal compression. [Conclusion] These results indicate that expiratory abdominal compression may be an effective alternative to the manual breathing assist procedure.

  8. The ecological limits of hydrologic alteration (ELOHA): A new framework for developing regional environmental flow standards

    Science.gov (United States)

    Poff, N.L.; Richter, B.D.; Arthington, A.H.; Bunn, S.E.; Naiman, R.J.; Kendy, E.; Acreman, M.; Apse, C.; Bledsoe, B.P.; Freeman, Mary C.; Henriksen, J.; Jacobson, R.B.; Kennen, J.G.; Merritt, D.M.; O'Keeffe, J. H.; Olden, J.D.; Rogers, K.; Tharme, R.E.; Warner, A.

    2010-01-01

    The flow regime is a primary determinant of the structure and function of aquatic and riparian ecosystems for streams and rivers. Hydrologic alteration has impaired riverine ecosystems on a global scale, and the pace and intensity of human development greatly exceeds the ability of scientists to assess the effects on a river-by-river basis. Current scientific understanding of hydrologic controls on riverine ecosystems and experience gained from individual river studies support development of environmental flow standards at the regional scale. 2. This paper presents a consensus view from a group of international scientists on a new framework for assessing environmental flow needs for many streams and rivers simultaneously to foster development and implementation of environmental flow standards at the regional scale. This framework, the ecological limits of hydrologic alteration (ELOHA), is a synthesis of a number of existing hydrologic techniques and environmental flow methods that are currently being used to various degrees and that can support comprehensive regional flow management. The flexible approach allows scientists, water-resource managers and stakeholders to analyse and synthesise available scientific information into ecologically based and socially acceptable goals and standards for management of environmental flows. 3. The ELOHA framework includes the synthesis of existing hydrologic and ecological databases from many rivers within a user-defined region to develop scientifically defensible and empirically testable relationships between flow alteration and ecological responses. These relationships serve as the basis for the societally driven process of developing regional flow standards. This is to be achieved by first using hydrologic modelling to build a 'hydrologic foundation' of baseline and current hydrographs for stream and river segments throughout the region. Second, using a set of ecologically relevant flow variables, river segments within the

  9. Countercurrent flow-limiting characteristics of a Savannah River Plant control rod septifoil

    International Nuclear Information System (INIS)

    Anderson, J.L.

    1992-07-01

    Experiments were performed at the Idaho National Engineering Laboratory to investigate the counter-current flow limiting characteristics of a Savannah River Plant control rod septifoil assembly. These experiments were unheated, using air and water as the working fluids. Results are presented in terms of the Wallis flooding correlation for several different control rod configurations. Flooding was observed to occur in the vicinity of the inlet slots/holes of the septifoil, rather than within the rod bundle at the location of the minimum flow area. Nearly identical flooding characteristics of the septifoil were observed for configurations with zero, three, and four rods inserted, but significantly different results occurred with 5 rods inserted

  10. SPH modelling of depth‐limited turbulent open channel flows over rough boundaries

    Science.gov (United States)

    Kazemi, Ehsan; Nichols, Andrew; Tait, Simon

    2016-01-01

    Summary A numerical model based on the smoothed particle hydrodynamics method is developed to simulate depth‐limited turbulent open channel flows over hydraulically rough beds. The 2D Lagrangian form of the Navier–Stokes equations is solved, in which a drag‐based formulation is used based on an effective roughness zone near the bed to account for the roughness effect of bed spheres and an improved sub‐particle‐scale model is applied to account for the effect of turbulence. The sub‐particle‐scale model is constructed based on the mixing‐length assumption rather than the standard Smagorinsky approach to compute the eddy‐viscosity. A robust in/out‐flow boundary technique is also proposed to achieve stable uniform flow conditions at the inlet and outlet boundaries where the flow characteristics are unknown. The model is applied to simulate uniform open channel flows over a rough bed composed of regular spheres and validated by experimental velocity data. To investigate the influence of the bed roughness on different flow conditions, data from 12 experimental tests with different bed slopes and uniform water depths are simulated, and a good agreement has been observed between the model and experimental results of the streamwise velocity and turbulent shear stress. This shows that both the roughness effect and flow turbulence should be addressed in order to simulate the correct mechanisms of turbulent flow over a rough bed boundary and that the presented smoothed particle hydrodynamics model accomplishes this successfully. © 2016 The Authors International Journal for Numerical Methods in Fluids Published by John Wiley & Sons Ltd PMID:28066121

  11. The role of flow limitation as an important diagnostic tool and clinical finding in mild sleep-disordered breathing

    Directory of Open Access Journals (Sweden)

    Nevin Arora

    2015-11-01

    Full Text Available Obstructive sleep apnea (OSA is defined by quantifying apneas and hypopneas along with symptoms suggesting sleep disruption. Subtler forms of sleep-disordered breathing can be missed when this criteria is used. Newer technologies allow for non-invasive detection of flow limitation, however consensus classification is needed. Subjects with flow limitation demonstrate electroencephalogram changes and clinical symptoms indicating sleep fragmentation. Flow limitation may be increased in special populations and treatment with nasal continuous positive airway pressure (CPAP has been shown to improve outcomes. Titrating CPAP to eliminate flow limitation may be associated with improved clinical outcomes compared to treating apneas and hypopneas.

  12. Short-term effects of positive expiratory airway pressure in patients being weaned from mechanical ventilation

    Directory of Open Access Journals (Sweden)

    Marcelo de Mello Rieder

    2009-05-01

    Full Text Available OBJECTIVE: To investigate the feasibility and the cardiorespiratory effects of using positive expiratory airway pressure, a physiotherapeutic tool, in comparison with a T-tube, to wean patients from mechanical ventilation. METHODS/DESIGN: A prospective, randomized, cross-over study. SETTING: Two intensive care units. PATIENTS AND INTERVENTIONS: We evaluated forty patients who met weaning criteria and had been mechanically-ventilated for more than 48 hours, mean age 59 years, including 23 males. All patients were submitted to the T-tube and Expiratory Positive Airway Pressure devices, at 7 cm H2O, during a 30-minute period. Cardiorespiratory variables including work of breathing, respiratory rate (rr, peripheral oxygen saturation (SpO2, heart rate (hr, systolic, diastolic and mean arterial pressures (SAP, DAP, MAP were measured in the first and thirtieth minutes. The condition was analyzed as an entire sample set (n=40 and was also divided into subconditions: chronic obstructive pulmonary disease (n=14 and non-chronic obstructive pulmonary disease (non- chronic obstructive pulmonary disease (n=26 categories. Comparisons were made using a t-test and Analysis of Variance. The level of significance was p < 0.05. RESULTS: Our data showed an increase in work of breathing in the first and thirtieth minutes in the EPAP condition (0.86+ 0.43 and 1.02+1.3 as compared with the T-tube condition (0.25+0.26 and 0.26+0.35 (p<0.05, verified by the flow-sensor monitor (values in J/L. No statistical differences were observed when comparing the Expiratory Positive Airway Pressure and T-tube conditions with regard to cardiorespiratory measurements. The same result was observed for both chronic obstructive pulmonary disease and non- chronic obstructive pulmonary disease subconditions. CONCLUSIONS: Our study demonstrated that, in weaning patients from mechanical ventilation, the use of a fixed level of Expiratory Positive Airway Pressure caused an increase in work of

  13. Edge shear flows and particle transport near the density limit of the HL-2A tokamak

    Science.gov (United States)

    Hong, R.; Tynan, G. R.; Diamond, P. H.; Nie, L.; Guo, D.; Long, T.; Ke, R.; Wu, Y.; Yuan, B.; Xu, M.; The HL-2A Team

    2018-01-01

    Edge shear flow and its effect on regulating turbulent transport have long been suspected to play an important role in plasmas operating near the Greenwald density limit n G. In this study, equilibrium profiles as well as the turbulent particle flux and Reynolds stress across the separatrix in the HL-2A tokamak are examined as nG is approached in ohmic L-mode discharges. As the normalized line-averaged density \\bar{n}_e/nG is raised, the shearing rate of the mean poloidal flow ω_sh drops, and the turbulent drive for the low-frequency zonal flow (the Reynolds power P_Re ) collapses. Correspondingly, the turbulent particle transport increases drastically with increasing collision rates. The geodesic acoustic modes (GAMs) gain more energy from the ambient turbulence at higher densities, but have smaller shearing rate than low-frequency zonal flows. The increased density also introduces decreased adiabaticity which not only enhances the particle transport but is also related to reduction in the eddy-tilting and the Reynolds power. Both effects may lead to cooling of edge plasmas and therefore the onset of MHD instabilities that limit the plasma density.

  14. Stability limits of superhydrophobic longitudinal microgrooves in high Reynolds number turbulent flows

    Science.gov (United States)

    Rastegari, Amirreza; Akhavan, Rayhaneh

    2017-11-01

    The stability of the liquid/gas interfaces on SuperHydrophobic (SH) Longitudinal MicroGrooves (LMGs) in high Reynolds number turbulent flows of practical interest is investigated by analytical extrapolation of DNS results in turbulent channel flow at Reτ0 222 and 442 with SH LMGs at protrusion angle of θ = -30o . Given that the magnitude of pressure fluctuations in turbulent channel flow scales as prms+ √{ ln(Reτ) } , it is found that the stability limits of SH LMGs diminishes by factors of 4 when the Reynolds number of the base flow increases from Reτ0 200 of DNS to Reτ0 105 -106 of practical applications. For SH LMGs operating at Weber numbers of We+0 ≡ μuτ0 / σ 3 ×10-3 - 1.5 ×10-2 , corresponding to friction velocities of uτ0 0.2 - 1 m/s, this limits the size of stable LMGs to g+0 5 - 30 at Reτ0 105 and g+0 4 - 20 at Reτ0 106 , and the maximum drag reductions to DRmax 20 - 30 % at Reτ0 105 and DRmax 10 - 20 % at Reτ0 106 .

  15. A probabilistic method for determining effluent temperature limits for flow instability for SRS reactors

    International Nuclear Information System (INIS)

    Hardy, B.J.; White, A.M.

    1990-06-01

    This manual describes the uncertainty analysis used to determine the effluent temperature limits for a Mark 22 charge in the Savannah River Site production reactors. The postulated accident scenario is a DEGB/LOCA resulting from a coolant pipe break at the plenum inlet accompanied by the safety rod failure described in the previous chapter. The analysis described in this manual is used to calculate the limits for the flow instability phase of the accident. For this phase of the accident, the limits criterion is that the Stanton number does not exceed 0.00455 [1]. The limits are determined for a specified 84% probability that the Stanton number will not exceed 0.00455 in any assembly in the core

  16. Possibilities and Limitations of CFD Simulation for Flashing Flow Scenarios in Nuclear Applications

    OpenAIRE

    Liao, Yixiang; Lucas, Dirk

    2017-01-01

    The flashing phenomenon is relevant to nuclear safety analysis, for example by a loss of coolant accident and safety release scenarios. It has been studied intensively by means of experiments and simulations with system codes, but computational fluid dynamics (CFD) simulation is still at the embryonic stage. Rapid increasing computer speed makes it possible to apply the CFD technology in such complex flow situations. Nevertheless, a thorough evaluation on the limitations and restrictions is s...

  17. The Economic Role and Limitations of Cooperatives: An Investment Cash Flow Derivation

    OpenAIRE

    Peterson, H. Christopher

    1992-01-01

    The economic role and limitations of cooperatives are derived using an approach based on investment cash flows and net present value. Cooperatives are viewed as an option for member investment as well as an option for member patronage. The investment approach yields results similar to the traditional paradigms that focus on patronage. In addition, the approach makes more explicit the impact of member investment on cooperative existence, valuation, performance measurement, and strategy options.

  18. Flutter-Limited Reconfiguration of a Flat Plate Bending in a Fluid Flow

    Science.gov (United States)

    Gosselin, Frederick; Sansas, Fabien; Prakash, Aviral; Bhati, Awan; Laurendeau, Eric

    Plants rely on their flexibility to change form and reduce their drag when subjected to fluid flow. Flexibility allows plants to reconfigure and reduce their drag, however it is well known that flexibility can also lead to a loss of stability and thus increased dynamical loads. Fluttering flags are a good example. In the present work, we consider the limitation to reconfiguration brought by a dynamic loss of stability in constant uniform flow. To understand the trade-off that flexibility brings to real plants in terms of drag reduction and loss of stability, we study an idealised two-dimensional system: a beam clamped at its centre and subjected to a normal flow. We combine wind tunnel experiments and numerical simulations to study how the beam bends in the flow statically when the flow velocity is increased until a critical value is reached and the beam starts fluttering. We observe the competition between reconfiguration and flutter in flat plates in a wind tunnel. We also adopt a computational approach coupling an ALE finite volume aerodynamics code to a finite difference solution of the large deformation beam equation. We find that for a lighter structure in a heavier fluid, the critical velocity is higher and more reconfiguration is possible without reaching an instability. NSERC.

  19. Coronal Rain in Magnetic Arcades: Rebound Shocks, Limit Cycles, and Shear Flows

    Science.gov (United States)

    Fang, X.; Xia, C.; Keppens, R.; Van Doorsselaere, T.

    2015-07-01

    We extend our earlier multidimensional, magnetohydrodynamic simulations of coronal rain occurring in magnetic arcades with higher resolution, grid-adaptive computations covering a much longer (>6 hr) time span. We quantify how blob-like condensations forming in situ grow along and across field lines and show that rain showers can occur in limit cycles, here demonstrated for the first time in 2.5D setups. We discuss dynamical, multi-dimensional aspects of the rebound shocks generated by the siphon inflows and quantify the thermodynamics of a prominence-corona transition-region-like structure surrounding the blobs. We point out the correlation between condensation rates and the cross-sectional size of loop systems where catastrophic cooling takes place. We also study the variations of the typical number density, kinetic energy, and temperature while blobs descend, impact, and sink into the transition region. In addition, we explain the mechanisms leading to concurrent upflows while the blobs descend. As a result, there are plenty of shear flows generated with relative velocity difference around 80 km s-1 in our simulations. These shear flows are siphon flows set up by multiple blob dynamics and they in turn affect the deformation of the falling blobs. In particular, we show how shear flows can break apart blobs into smaller fragments, within minutes.

  20. Genetic differentiation of the malaria vector Anopheles gambiae across Nigeria suggests that selection limits gene flow.

    Science.gov (United States)

    Onyabe, D Y; Conn, J E

    2001-12-01

    Gene flow was investigated in Anopheles gambiae from eight localities that span the ecological zones of Nigeria (arid savanna zones in the north gradually turn into humid forest zones in the south). Genetic differentiation was measured over 10 microsatellite loci and, to determine any effects of selection, five loci were located within chromosome inversions and the other five were outside inversions. Over all loci, the largest estimates of differentiation were in comparisons between localities in the savanna vs. forest zones (range FST 0.024-0.087, Nm 2.6-10.1; RST 0.014-0.100, Nm 2.2-16.4). However, three loci located within inversions on chromosome II, whose frequencies varied clinically from north to south, were responsible for virtually all of the differentiation. When the three loci were removed, genetic distances across the remaining seven loci were markedly reduced even between localities in the forest and savanna zones (range FST 0.001-0.019, Nm 12.7-226.1) or no longer significant (P > 0.05) in the case of RST. Although tests of isolation by distance gave seemingly equivocal results, geographical distance does not appear to limit gene flow. These observations suggest that gene flow is extensive across the country but that selection on genes located within some inversions on chromosome II counters the homogenizing effects of gene flow.

  1. Reaching for the limits in continuous-flow dielectrophoretic DNA analysis.

    Science.gov (United States)

    Täuber, Sarah; Kunze, Lena; Grauberger, Oleg; Grundmann, Armin; Viefhues, Martina

    2017-12-04

    The efficient purification and analysis of topological DNA variants is mandatory for many state-of-the-art molecular medicine technologies, like gene- and cancer-therapy as well as plasmid vaccination. In this work, we exploit dielectrophoresis (DEP) for a fast and efficient continuous-flow separation and analysis that goes beyond the standard methods of gel electrophoresis and capillary electrophoresis. The aim of this work was to reach for the limits in dielectrophoretic analysis of DNA regarding the size resolution and the topological conformation. A continuous-flow analytical separation of analyte mixtures of small linear DNA-fragments (10.0 kbp, 8.0 kbp, 6.0 kbp, and 5.0 kbp) and topological DNA variants (linear and supercoiled conformation) was investigated. We present a world record in the minimal size difference of 16.7% of DNA samples that can be resolved in a dielectrophoretic continuous-flow separation. Moreover, we demonstrate for the first time a microfluidic continuous-flow separation of DNA molecules based on their topological conformation. Since dielectrophoresis is virtually label-free, it offers a fast in-process quality control with low consumption, e.g. for the production of gene vaccines.

  2. Variable speed limit strategies analysis with mesoscopic traffic flow model based on complex networks

    Science.gov (United States)

    Li, Shu-Bin; Cao, Dan-Ni; Dang, Wen-Xiu; Zhang, Lin

    As a new cross-discipline, the complexity science has penetrated into every field of economy and society. With the arrival of big data, the research of the complexity science has reached its summit again. In recent years, it offers a new perspective for traffic control by using complex networks theory. The interaction course of various kinds of information in traffic system forms a huge complex system. A new mesoscopic traffic flow model is improved with variable speed limit (VSL), and the simulation process is designed, which is based on the complex networks theory combined with the proposed model. This paper studies effect of VSL on the dynamic traffic flow, and then analyzes the optimal control strategy of VSL in different network topologies. The conclusion of this research is meaningful to put forward some reasonable transportation plan and develop effective traffic management and control measures to help the department of traffic management.

  3. A state of the art on the flooding phenomena and countercurrent flow limiting modeling

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Young Jong; Chang, Won Pyo [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    1996-07-01

    Countercurrent flow limiting phenomenon and its modeling for vertical and nearly horizontal pipes has been reviewed in two phase flow. A number of analytical and empirical model have been developed for flooding in the vertical pipes and annulars. These may be classified as stability theory, envelope theory, static equilibrium theory, slug formation theory, Wallis correlation, and Kutateladze correlation. The theories and empirical correlations are reviewed and comparison with the various experimental data. The scatter of the experimental data is large because of the different flooding condition and because of the influence of the experimental conditions. Application of flooding for PWR best estimate system codes is reviewed. The codes provide the user options to implement CCFL correlation for the specific geometry. The codes can accommodate generally Wallis, Kutateladze, or Bankoff correlation. 4 tabs., 36 figs., 52 refs. (Author).

  4. Limiter

    Science.gov (United States)

    Cohen, S.A.; Hosea, J.C.; Timberlake, J.R.

    1984-10-19

    A limiter with a specially contoured front face is provided. The front face of the limiter (the plasma-side face) is flat with a central indentation. In addition, the limiter shape is cylindrically symmetric so that the limiter can be rotated for greater heat distribution. This limiter shape accommodates the various power scrape-off distances lambda p, which depend on the parallel velocity, V/sub parallel/, of the impacting particles.

  5. Filamentous sieve element proteins are able to limit phloem mass flow, but not phytoplasma spread.

    Science.gov (United States)

    Pagliari, Laura; Buoso, Sara; Santi, Simonetta; Furch, Alexandra C U; Martini, Marta; Degola, Francesca; Loschi, Alberto; van Bel, Aart J E; Musetti, Rita

    2017-06-15

    In Fabaceae, dispersion of forisomes-highly ordered aggregates of sieve element proteins-in response to phytoplasma infection was proposed to limit phloem mass flow and, hence, prevent pathogen spread. In this study, the involvement of filamentous sieve element proteins in the containment of phytoplasmas was investigated in non-Fabaceae plants. Healthy and infected Arabidopsis plants lacking one or two genes related to sieve element filament formation-AtSEOR1 (At3g01680), AtSEOR2 (At3g01670), and AtPP2-A1 (At4g19840)-were analysed. TEM images revealed that phytoplasma infection induces phloem protein filament formation in both the wild-type and mutant lines. This result suggests that, in contrast to previous hypotheses, sieve element filaments can be produced independently of AtSEOR1 and AtSEOR2 genes. Filament presence was accompanied by a compensatory overexpression of sieve element protein genes in infected mutant lines in comparison with wild-type lines. No correlation was found between phloem mass flow limitation and phytoplasma titre, which suggests that sieve element proteins are involved in defence mechanisms other than mechanical limitation of the pathogen. © The Author 2017. Published by Oxford University Press on behalf of the Society for Experimental Biology.

  6. Calculation of the capnographic index based on expiratory molar mass-volume-curves--a suitable tool to screen for cystic fibrosis lung disease.

    Science.gov (United States)

    Fuchs, Susanne I; Junge, Sibylle; Ellemunter, Helmut; Ballmann, Manfred; Gappa, Monika

    2013-05-01

    Volumetric capnography reflecting the course of CO2-exhalation is used to assess ventilation inhomogeneity. Calculation of the slope of expiratory phase 3 and the capnographic index (KPIv) from expirograms allows quantification of extent and severity of small airway impairment. However, technical limitations have hampered more widespread use of this technique. Using expiratory molar mass-volume-curves sampled with a handheld ultrasonic flow sensor during tidal breathing is a novel approach to extract similar information from expirograms in a simpler manner possibly qualifying as a screening tool for clinical routine. The aim of the present study was to evaluate calculation of the KPIv based on molar mass-volume-curves sampled with an ultrasonic flow sensor in patients with CF and controls by assessing feasibility, reproducibility and comparability with the Lung Clearance Index (LCI) derived from multiple breath washout (MBW) used as the reference method. Measurements were performed in patients with CF and healthy controls during a single test occasion using the EasyOne Pro, MBW Module (ndd Medical Technologies, Switzerland). Capnography and MBW were performed in 87/96 patients with CF and 38/42 controls, with a success rate of 90.6% for capnography. Mean age (range) was 12.1 (4-25) years. Mean (SD) KPIv was 6.94 (3.08) in CF and 5.10 (2.06) in controls (p=0.001). Mean LCI (SD) was 8.0 (1.4) in CF and 6.2 (0.4) in controls (p=molar mass-volume-curves is feasible. KPIv is significantly different between patients with CF and controls and correlates with the LCI. However, individual data revealed a relevant overlap between patients and controls requiring further evaluation, before this method can be recommended for clinical use. Copyright © 2012 European Cystic Fibrosis Society. Published by Elsevier B.V. All rights reserved.

  7. Upper-airway flow limitation and transcutaneous carbon dioxide during sleep in normal pregnancy.

    Science.gov (United States)

    Rimpilä, Ville; Jernman, Riina; Lassila, Katariina; Uotila, Jukka; Huhtala, Heini; Mäenpää, Johanna; Polo, Olli

    2017-08-01

    Sleep during pregnancy involves a physiological challenge to provide sufficient gas exchange to the fetus. Enhanced ventilatory responses to hypercapnia and hypoxia may protect from deficient gas exchange, but sleep-disordered breathing (SDB) may predispose to adverse events. The aim of this study was to analyze sleep and breathing in healthy pregnant women compared to non-pregnant controls, with a focus on CO 2 changes and upper-airway flow limitation. Healthy women in the third trimester and healthy non-pregnant women with normal body mass index (BMI) were recruited for polysomnography. Conventional analysis of sleep and breathing was performed. Transcutaneous carbon dioxide (TcCO 2 ) was determined for each sleep stage. Flow-limitation was analyzed using the flattening index and TcCO 2 values were recorded for every inspiration. Eighteen pregnant women and 12 controls were studied. Pregnancy was associated with shorter sleep duration and more superficial sleep. Apnea-hypopnea index, arterial oxyhemoglobin desaturation, flow-limitation, snoring or periodic leg movements were similar in the two groups. Mean SaO 2 and minimum SaO 2 were lower and average heart rate was higher in the pregnant group. TcCO 2 levels did not differ between groups but variance of TcCO 2 was smaller in pregnant women during non-rapid eye movement (NREM). TcCO 2 profiles showed transient TcCO 2 peaks, which seem specific to pregnancy. Healthy pregnancy does not predispose to SDB. Enhanced ventilatory control manifests as narrowing threshold of TcCO 2 between wakefulness and sleep. Pregnant women have a tendency for rapid CO 2 increases during sleep which might have harmful consequences if not properly compensated. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. Johnson-Segalman -- Saint-Venant equations for viscoelastic shallow flows in the elastic limit

    OpenAIRE

    Boyaval, Sébastien

    2016-01-01

    The shallow-water equations of Saint-Venant, often used to model the long-wave dynamics of free-surface flows driven by inertia and hydrostatic pressure, can be generalized to account for the elongational rheology of non-Newtonian fluids too. We consider here the $4 \\times 4$ shallow-water equations generalized to viscoelastic fluids using the Johnson-Segalman model in the elastic limit (i.e. at infinitely-large Deborah number, when source terms vanish). The system of nonlinear first-order eq...

  9. Partial analysis of wind power limit in an electric micro system using continuation power flow

    International Nuclear Information System (INIS)

    Fiallo Guerrero, Jandry; Santos Fuentefria, Ariel; Castro Fernández, Miguel

    2013-01-01

    The wind power insertion in the power system is an important issue and can create some instability problems in voltage and system frequency due to stochastic origin of wind. Know the Wind Power Limit that can insert in an electric grid without losing stability is a very important matter. Existing in bibliography a few methods for calculation of wind power limit, some of them are based in static constrains, an example is a method based in a continuation power flow analysis. In the present work the method is applied in an electric micro system formed when the system is disconnected of the man grid, the main goal was prove the method in a weak and island network. The software used in the simulations was the Power System Analysis Toolbox (PSAT). (author)

  10. Lactate delivery (not oxygen) limits hepatic gluconeogenesis when blood flow is reduced.

    Science.gov (United States)

    Sumida, Ken D; Urdiales, Jerry H; Donovan, Casey M

    2006-01-01

    The purpose of this study was to determine, using the isolated liver perfusion technique, whether the limiting factor for hepatic gluconeogenesis (GNG) from lactate was precursor delivery or oxygen availability during reduced flow rates of 0.85 or 0.60 ml.min(-1).g liver(-1). After a 24-h fast, three different experimental protocols were employed. Protocol 1 examined the impact on GNG when reservoir lactate concentration was maintained but oxygen delivery was elevated via increases in hematocrit (Hct). Elevating the Hct from 22.5+/- 0.8% to 30.9+/- 0.4% at a blood flow of 0.89+/- 0.01 ml.min(-1).g liver(-1) increased the oxygen consumption (Vo(2)) but did not augment GNG. Similarly, when the Hct was elevated from 22.5+/- 0.8% to 41.5+/- 0.7% at 0.59+/- 0.04 ml.min(-1).g liver(-1), Vo(2) was increased, but GNG was unaffected. Protocol 2 examined the impact on GNG when Hct was maintained but precursor delivery was elevated via increases in reservoir lactate concentration ([LA]). Specifically, elevating the [LA] from 2.31+/- 0.07 to 3.61+/- 0.33 mM at a flow rate of 0.82+/- 0.04 ml.min(-1).g liver(-1) significantly increased GNG. Similarly, elevating the [LA] from 2.31+/- 0.07 to 4.24+/- 0.37 mM at a flow rate of 0.58+/- 0.02 ml.min(-1).g liver(-1) increased GNG. Finally, we examined the impact of increasing both the oxygen and lactate delivery (Protocol 3). Again, Vo(2) was elevated with increased oxygen delivery, but GNG was not augmented beyond that observed with elevations in lactate delivery alone, i.e., Protocol 2. The results indicate that, during decrements in blood flow, GNG is limited primarily by precursor delivery, not oxygen availability.

  11. Upgraded flowing liquid lithium limiter for improving Li coverage uniformity and erosion resistance in EAST device

    Science.gov (United States)

    Zuo, G. Z.; Hu, J. S.; Maingi, R.; Yang, Q. X.; Sun, Z.; Huang, M.; Chen, Y.; Yuan, X. L.; Meng, X. C.; Xu, W.; Gentile, C.; Carpe, A.; Diallo, A.; Lunsford, R.; Mansfield, D.; Osborne, T.; Tritz, K.; Li, J. G.

    2017-12-01

    We report on design and technology improvements for a flowing liquid lithium (FLiLi) limiter inserted into auxiliary heated discharges in the experimental advanced superconducting tokamak device. In order to enhance Li coverage uniformity and erosion resistance, a new liquid Li distributor with homogenous channels was implemented. In addition, two independent electromagnetic pumps and a new horizontal capillary structure contributed to an improvement in the observed Li flow uniformity (from 30% in the previous FLiLi design to >80% in this FLiLi design). To improve limiter surface erosion resistance, hot isostatic press technology was applied, which improved the thermal contact between thin stainless steel protective layers covering the Cu heat sink. The thickness of the stainless steel layer was increased from 0.1 mm to 0.5 mm, which also helped macroscopic erosion resilience. Despite the high auxiliary heating power up to 4.5 MW, no Li bursts were recorded from FLiLi, underscoring the improved performance of this new design.

  12. L^1 singular limit for relaxation and viscosity approximations of extended traffic flow models

    Directory of Open Access Journals (Sweden)

    Christian Klingenberg

    2003-03-01

    Full Text Available This paper considers the Cauchy problem for an extended traffic flow model with $L^1$-bounded initial data. A solution of the corresponding equilibrium equation with $L^1$-bounded initial data is given by the limit of solutions of viscous approximations of the original system as the dissipation parameter $epsilon$ tends to zero more slowly than the response time $au$. The proof of convergence is obtained by applying the Young measure to solutions introduced by DiPerna and, based on the estimate $$ | ho(t,x| leq sqrt {| ho_0(x|_1/(ct} $$ derived from one of Lax's results and Diller's idea, the limit function $ ho(t,x$ is shown to be a $L^1$-entropy week solution. A direct byproduct is that we can get the existence of $L^1$-entropy solutions for the Cauchy problem of the scalar conservation law with $L^1$-bounded initial data without any restriction on the growth exponent of the flux function provided that the flux function is strictly convex. Our result shows that, unlike the weak solutions of the incompressible fluid flow equations studied by DiPerna and Majda in [6], for convex scalar conservation laws with $L^1$-bounded initial data, the concentration phenomenon will never occur in its global entropy solutions.

  13. Diagnostic methods to assess inspiratory and expiratory muscle strength

    OpenAIRE

    Caruso, Pedro; Albuquerque, André Luis Pereira de; Santana, Pauliane Vieira; Cardenas, Leticia Zumpano; Ferreira, Jeferson George; Prina, Elena; Trevizan, Patrícia Fernandes; Pereira, Mayra Caleffi; Iamonti, Vinicius; Pletsch, Renata; Macchione, Marcelo Ceneviva; Carvalho, Carlos Roberto Ribeiro

    2015-01-01

    Impairment of (inspiratory and expiratory) respiratory muscles is a common clinical finding, not only in patients with neuromuscular disease but also in patients with primary disease of the lung parenchyma or airways. Although such impairment is common, its recognition is usually delayed because its signs and symptoms are nonspecific and late. This delayed recognition, or even the lack thereof, occurs because the diagnostic tests used in the assessment of respiratory muscle strength are not w...

  14. Space-charge-limited ion flow through an ionizing neutral layer

    International Nuclear Information System (INIS)

    Duvall, R.E.; Litwin, C.; Maron, Y.

    1993-01-01

    Space-charge-limited ion flow through an ionizing layer of neutral atoms is studied. The ion flow is between two parallel conducting plates (anode and cathode) with an externally applied voltage between them. An expanding layer of neutral atoms is adjacent to the anode surface, extending a finite distance into the anode--cathode gap. All ions originate either from the anode surface or from the ionization of neutrals; electrons originate only from ionization. Electrons are strongly magnetized by an externally applied, time-independent direct current (dc) magnetic field directed across the ion flow. The ions are unmagnetized, all motion being perpendicular to the conducting plates. Two different models of the anode layer were used to analyze this problem: a multifluid steady-state model and a single fluid time-dependent model. From both models it was found that the anode surface becomes shielded after the ion flux from the ionizing layer becomes larger than the space-charge-limited flux of the reduced gap between the neutral layer and cathode. Comparison was made between the time-dependent model and results from magnetically insulated ion beam diode (MID) experiments. Using an initial areal density of neutral hydrogen and carbon equal to the final observed electron areal density, comparison was made between calculated plasma shielding times and upper bounds on the shielding time observed in experiments. It was found that a layer of neutral hydrogen must contain a minimum of 15% carbon (by number density) to explain the rapid electric field screening observed in experiments

  15. Diagnostic methods to assess inspiratory and expiratory muscle strength

    Directory of Open Access Journals (Sweden)

    Pedro Caruso

    2015-04-01

    Full Text Available Impairment of (inspiratory and expiratory respiratory muscles is a common clinical finding, not only in patients with neuromuscular disease but also in patients with primary disease of the lung parenchyma or airways. Although such impairment is common, its recognition is usually delayed because its signs and symptoms are nonspecific and late. This delayed recognition, or even the lack thereof, occurs because the diagnostic tests used in the assessment of respiratory muscle strength are not widely known and available. There are various methods of assessing respiratory muscle strength during the inspiratory and expiratory phases. These methods are divided into two categories: volitional tests (which require patient understanding and cooperation; and non-volitional tests. Volitional tests, such as those that measure maximal inspiratory and expiratory pressures, are the most commonly used because they are readily available. Non-volitional tests depend on magnetic stimulation of the phrenic nerve accompanied by the measurement of inspiratory mouth pressure, inspiratory esophageal pressure, or inspiratory transdiaphragmatic pressure. Another method that has come to be widely used is ultrasound imaging of the diaphragm. We believe that pulmonologists involved in the care of patients with respiratory diseases should be familiar with the tests used in order to assess respiratory muscle function.Therefore, the aim of the present article is to describe the advantages, disadvantages, procedures, and clinical applicability of the main tests used in the assessment of respiratory muscle strength.

  16. Abdominal expiratory muscle activity in anesthetized vagotomized neonatal rats.

    Science.gov (United States)

    Iizuka, Makito

    2009-05-01

    The pattern of respiratory activity in abdominal muscles was studied in anesthetized, spontaneously breathing, vagotomized neonatal rats at postnatal days 0-3. Anesthesia (2.0% isoflurane, 50% O(2)) depressed breathing and resulted in hypercapnia. Under this condition, abdominal muscles showed discharge late in the expiratory phase (E2 activity) in most rats. As the depth of anesthesia decreased, the amplitude of discharges in the diaphragm and abdominal muscles increased. A small additional burst frequently occurred in abdominal muscles just after the termination of diaphragmatic inspiratory activity (E1 or postinspiratory activity). Since this E1 activity is not often observed in adult rats, the abdominal respiratory pattern likely changes during postnatal development. Anoxia-induced gasping after periodic expiratory activity without inspiratory activity, and in most rats, abdominal expiratory activity disappeared before terminal apnea. These results suggest that a biphasic abdominal motor pattern (a combination of E2 and E1 activity) is a characteristic of vagotomized neonatal rats during normal respiration.

  17. Enhanced Dissipation, Hypoellipticity, and Anomalous Small Noise Inviscid Limits in Shear Flows

    Science.gov (United States)

    Bedrossian, Jacob; Coti Zelati, Michele

    2017-06-01

    We analyze the decay and instant regularization properties of the evolution semigroups generated by two-dimensional drift-diffusion equations in which the scalar is advected by a shear flow and dissipated by full or partial diffusion. We consider both the space-periodic T^2 setting and the case of a bounded channel T × [0,1] with no-flux boundary conditions. In the infinite Péclet number limit (diffusivity {ν\\to 0}), our work quantifies the enhanced dissipation effect due to the shear. We also obtain hypoelliptic regularization, showing that solutions are instantly Gevrey regular even with only partial diffusion. The proofs rely on localized spectral gap inequalities and ideas from hypocoercivity with an augmented energy functional with weights replaced by pseudo-differential operators (of a rather simple form). As an application, we study small noise inviscid limits of invariant measures of stochastic perturbations of passive scalars, and show that the classical Freidlin scaling between noise and diffusion can be modified. In particular, although statistically stationary solutions blow up in {H^1} in the limit {ν \\to 0}, we show that viscous invariant measures still converge to a unique inviscid measure.

  18. Numerical simulation study on the air/water countercurrent flow limitation in nuclear reactors

    Energy Technology Data Exchange (ETDEWEB)

    Morghi, Youssef; Mesquita, Amir Z., E-mail: ssfmorghi@gmail.com, E-mail: amir@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil); Puente, Jesus, E-mail: jpuente720@gmail.com [Centro Federal de Educaçao Tecnologica Celso Suckowda Fonseca (CEFET), Angra dos Reis, RJ (Brazil); Baliza, Ana R., E-mail: baliza@eletronuclear.gov.br [Eletrobras Eletronuclear Angra dos Reis, RJ (Brazil)

    2017-07-01

    After a loss-of-coolant accident (LOCA) in a Pressurized Water Reactor (PWR), the temperature of the fuel elements cladding increases dramatically due to the heat produced by the fission products decay, which is not adequately removed by the vapor contained in the core. In order to avoid this sharp rise in temperature and consequent melting of the core, the Emergency Core Cooling System is activated. This system initially injects borated water from accumulator tanks of the reactor through the inlet pipe (cold leg) and the outlet pipe (hot leg), or through the cold leg only, depending on the plant manufacturer. Some manufacturers add to this, direct injection into the upper plenum of the reactor. The penetration of water into the reactor core is a complex thermo fluid dynamic process because it involves the mixing of water with the vapor contained in the reactor, added to that generated in the contact of the water with the still hot surfaces in various geometries. In some critical locations, the vapor flowing in the opposite direction of the water can control the penetration of this into the core. This phenomenon is known as Countercurrent Flow Limitation (CCFL) or Flooding, and it is characterized by the control that a gas exerts in the liquid flow in the opposite direction. This work presents a proposal to use a CFD to simulate the CCFL phenomenon. Numerical computing can provide important information and data that is difficult or expensive to measure or test experimentally. Given the importance of computational science today, it can be considered a third and independent branch of science on an equal footing with the theoretical and experimental sciences. (author)

  19. Combined micro and macro geodynamic modelling of mantle flow: methods, potentialities and limits.

    Science.gov (United States)

    Faccenda, M.

    2015-12-01

    Over the last few years, geodynamic simulations aiming at reconstructing the Earth's internal dynamics have increasingly attempted to link processes occurring at the micro (i.e., strain-induced lattice preferred orientation (LPO) of crystal aggregates) and macro scale (2D/3D mantle convection). As a major outcome, such a combined approach results in the prediction of the modelled region's elastic properties that, in turn, can be used to perform seismological synthetic experiments. By comparison with observables, the geodynamic simulations can then be considered as a good numerical analogue of specific tectonic settings, constraining their deep structure and recent tectonic evolution. In this contribution, I will discuss the recent methodologies, potentialities and current limits of combined micro- and macro-flow simulations, with particular attention to convergent margins whose dynamics and deep structure is still the object of extensive studies.

  20. Externally Phase-Locked Flux Flow Oscillator for Submm Integrated Receivers; Achievements and Limitations

    DEFF Research Database (Denmark)

    Koshelets, V. P.; Shitov, S. V.; Dmitriev, P. N.

    2003-01-01

    A Josephson Flux Flow Oscillator (FFO) is the most developed superconducting local oscillator for integration with an SIS mixer in a single-chip submm-wave receiver. Recently, using a new FFO design, a free-running linewidth less than or equal to10 MHz has been measured in the frequency range up...... to 712 GHz, limited only by the gap frequency of Nb. This enabled us to phase lock the FFO in the frequency range 500-712 GHz where continuous frequency tuning is possible; resulting in an absolute FFO phase noise as low as -80 dBc at 707 GHz. Comprehensive measurements of the FFO radiation linewidth...... have been performed using an integrated SIS harmonic mixer. The influence of FFO parameters on radiation linewidth, particularly the effect of the differential resistances associated both with the bias current and the applied magnetic field has been studied in order to further optimize the FFO design...

  1. Flow-Through Stream Modeling with MODFLOW and MT3D: Certainties and Limitations.

    Science.gov (United States)

    Ben Simon, Rose; Bernard, Stéphane; Meurville, Charles; Rebour, Vincent

    2015-01-01

    This paper aims to assess MODFLOW and MT3D capabilities for simulating the spread of contaminants from a river exhibiting an unusual relationship with an alluvial aquifer, with the groundwater head higher than the river head on one side and lower on the other (flow-through stream). A series of simulation tests is conducted using a simple hypothetical model so as to characterize and quantify these limitations. Simulation results show that the expected contaminant spread could be achieved with a specific configuration composed of two sets of parameters: (1) modeled object parameters (hydraulic groundwater gradient, hydraulic conductivity values of aquifer and streambed), and (2) modeling parameters (vertical discretization of aquifer, horizontal refinement of stream modeled with River [RIV] package). The influence of these various parameters on simulation results is investigated, and potential complications and errors are identified. Contaminant spread from stream to aquifer is not always reproduced by MT3D due to the RIV package's inability to simulate lateral exchange fluxes between stream and aquifer. This paper identifies the need for a MODFLOW streamflow package allowing lateral stream-aquifer interactions and streamflow routine calculations. Such developments could be of particular interest for modeling contaminated flow-through streams. © 2015, National Ground Water Association.

  2. Blow-out limits of nonpremixed turbulent jet flames in a cross flow at atmospheric and sub-atmospheric pressures

    KAUST Repository

    Wang, Qiang

    2015-07-22

    The blow-out limits of nonpremixed turbulent jet flames in cross flows were studied, especially concerning the effect of ambient pressure, by conducting experiments at atmospheric and sub-atmospheric pressures. The combined effects of air flow and pressure were investigated by a series of experiments conducted in an especially built wind tunnel in Lhasa, a city on the Tibetan plateau where the altitude is 3650 m and the atmospheric pressure condition is naturally low (64 kPa). These results were compared with results obtained from a wind tunnel at standard atmospheric pressure (100 kPa) in Hefei city (altitude 50 m). The size of the fuel nozzles used in the experiments ranged from 3 to 8 mm in diameter and propane was used as the fuel. It was found that the blow-out limit of the air speed of the cross flow first increased (“cross flow dominant” regime) and then decreased (“fuel jet dominant” regime) as the fuel jet velocity increased in both pressures; however, the blow-out limit of the air speed of the cross flow was much lower at sub-atmospheric pressure than that at standard atmospheric pressure whereas the domain of the blow-out limit curve (in a plot of the air speed of the cross flow versus the fuel jet velocity) shrank as the pressure decreased. A theoretical model was developed to characterize the blow-out limit of nonpremixed jet flames in a cross flow based on a Damköhler number, defined as the ratio between the mixing time and the characteristic reaction time. A satisfactory correlation was obtained at relative strong cross flow conditions (“cross flow dominant” regime) that included the effects of the air speed of the cross flow, fuel jet velocity, nozzle diameter and pressure.

  3. The effect of water temperature and flow on respiration in barnacles: patterns of mass transfer versus kinetic limitation.

    Science.gov (United States)

    Nishizaki, Michael T; Carrington, Emily

    2014-06-15

    In aquatic systems, physiological processes such as respiration, photosynthesis and calcification are potentially limited by the exchange of dissolved materials between organisms and their environment. The nature and extent of physiological limitation is, therefore, likely to be dependent on environmental conditions. Here, we assessed the metabolic sensitivity of barnacles under a range of water temperatures and velocities, two factors that influence their distribution. Respiration rates increased in response to changes in temperature and flow, with an interaction where flow had less influence on respiration at low temperatures, and a much larger effect at high temperatures. Model analysis suggested that respiration is mass transfer limited under conditions of low velocity (temperature (20-25°C). In contrast, limitation by uptake reaction kinetics, when the biotic capacity of barnacles to absorb and process oxygen is slower than its physical delivery by mass transport, prevailed at high flows (40-150 cm s(-1)) and low temperatures (5-15°C). Moreover, there are intermediate flow-temperature conditions where both mass transfer and kinetic limitation are important. Behavioral monitoring revealed that barnacles fully extend their cirral appendages at low flows and display abbreviated 'testing' behaviors at high flows, suggesting some form of mechanical limitation. In low flow-high temperature treatments, however, barnacles displayed distinct 'pumping' behaviors that may serve to increase ventilation. Our results suggest that in slow-moving waters, respiration may become mass transfer limited as temperatures rise, whereas faster flows may serve to ameliorate the effects of elevated temperatures. Moreover, these results underscore the necessity for approaches that evaluate the combined effects of multiple environmental factors when examining physiological and behavioral performance. © 2014. Published by The Company of Biologists Ltd.

  4. Possibilities and Limitations of CFD Simulation for Flashing Flow Scenarios in Nuclear Applications

    Directory of Open Access Journals (Sweden)

    Yixiang Liao

    2017-01-01

    Full Text Available The flashing phenomenon is relevant to nuclear safety analysis, for example by a loss of coolant accident and safety release scenarios. It has been studied intensively by means of experiments and simulations with system codes, but computational fluid dynamics (CFD simulation is still at the embryonic stage. Rapid increasing computer speed makes it possible to apply the CFD technology in such complex flow situations. Nevertheless, a thorough evaluation on the limitations and restrictions is still missing, which is however indispensable for reliable application, as well as further development. In the present work, the commonly-used two-fluid model with different mono-disperse assumptions is used to simulate various flashing scenarios. With the help of available experimental data, the results are evaluated, and the limitations are discussed. A poly-disperse method is found necessary for a reliable prediction of mean bubble size and phase distribution. The first attempts to trace the evolution of the bubble size distribution by means of poly-disperse simulations are made.

  5. ELM Suppression and performance improvement with a flowing liquid lithium limiter in EAST

    Science.gov (United States)

    Zuo, G. Z.; Hu, J. S.; Maingi, R.; Sun, Z.; Xu, W.; Li, J. G.; Diallo, A.; Lunsford, R.; Osborne, T.; Tritz, K.; EAST Team

    2017-10-01

    Improvements in plasma performance were observed using a second-generation flowing liquid lithium limiter (FLiLi) in EAST. Compared to the H mode discharges without FLiLi, ELM frequency and amplitude were both lower with FLiLi. Also, ELM frequency and amplitude gradually decreased discharge-by-discharge with FLiLi, similar to the gradual ELM mitigation by real-time Li aerosol injection in successive discharges. Moreover, transient ELM-free H-modes with a strong increase of WMHD and H98 were observed for the first time with FLiLi. During the ELM-free phases, MHD activity interpreted from high frequency Mirnov probes differed from activity in the ELMy phases. In addition to the typical low-frequency 50 kHz edge coherent MHD mode (ECM), a second mode 220-240 kHz also was observed in the ELM-free phase. By computing the Li efflux from the FLiLi limiter surface, it was found that the Li efflux from sputtering during discharges and evaporation between discharges was comparable to the typical mass delivery rates used for Li powder injection rate during plasma operation in EAST. Therefore, gradual accumulation of Li in EAST via real time Li efflux from the FLiLi surface produces similar effects to aerosol injection, i.e. reduced recycling, enhanced fluctuations, and ELM mitigation.

  6. Enhancement of the detection limit for lateral flow immunoassays: evaluation and comparison of bioconjugates.

    Science.gov (United States)

    Linares, Elisângela M; Kubota, Lauro T; Michaelis, Jens; Thalhammer, Stefan

    2012-01-31

    There is an increasing demand for convenient and accurate point-of-care tools that can detect and diagnose different stages of a disease in remote or impoverished settings. In recent years, lateral flow immunoassays (LFIA) have been indicated as a suitable medical diagnostic tool for these environments because they require little or no sample preparation, provide rapid and reliable results with no electronic components and thus can be manufactured at low costs and operated by unskilled personnel. However, even though they have been successfully applied to acute and chronic disease detection, LFIA based on gold nanoparticles, the standard marker, show serious limitations when high sensitivity is needed, such as early stage disease detection. Moreover, based on the lack of comparative information for label performance, significant optimization of the systems that are currently in use might be possible. To this end, in the presented work, we compare the detection limit between the four most used labels: colloidal-gold, silver enhanced gold, blue latex bead and carbon black nanoparticles. Preliminary results were obtained by using the biotin-streptavidin coupling as a model system and showed that carbon black had a remarkably low detection limit of 0.01 μg/mL in comparison to 0.1 μg/mL, 1 μg/mL and 1mg/mL for silver-coated gold nanoparticles, gold nanoparticles and polystyrene beads, respectively. Therefore, as a proof of concept, carbon black was used in a detection system for Dengue fever. This was achieved by immobilizing monoclonal antibodies for the nonstructural glycoprotein (NS1) of the Dengue virus to carbon black. We found that the colorimetric detection limit of 57 ng/mL for carbon black was ten times lower than the 575 ng/mL observed for standard gold nanoparticles; which makes it sensitive enough to diagnose a patient on the first days of infection. We therefore conclude that, careful screening of detection labels should be performed as a necessary step

  7. Axial-Flow Turbine Rotor Discharge-Flow Overexpansion and Limit-Loading Condition, Part I: Computational Fluid Dynamics (CFD) Investigation

    Science.gov (United States)

    Chen, Shu-Cheng S.

    2017-01-01

    A Computational Fluid Dynamic (CFD) investigation is conducted over a two-dimensional axial-flow turbine rotor blade row to study the phenomena of turbine rotor discharge flow overexpansion at subcritical, critical, and supercritical conditions. Quantitative data of the mean-flow Mach numbers, mean-flow angles, the tangential blade pressure forces, the mean-flow mass flux, and the flow-path total pressure loss coefficients, averaged or integrated across the two-dimensional computational domain encompassing two blade-passages, are obtained over a series of 14 inlet-total to exit-static pressure ratios, from 1.5 (un-choked; subcritical condition) to 10.0 (supercritical with excessively high pressure ratio.) Detailed flow features over the full domain-of-computation, such as the streamline patterns, Mach contours, pressure contours, blade surface pressure distributions, etc. are collected and displayed in this paper. A formal, quantitative definition of the limit loading condition based on the channel flow theory is proposed and explained. Contrary to the comments made in the historical works performed on this subject, about the deficiency of the theoretical methods applied in analyzing this phenomena, using modern CFD method for the study of this subject appears to be quite adequate and successful. This paper describes the CFD work and its findings.

  8. Analysis of Limit Cycle Oscillation/Transonic High Alpha Flow Visualization. Part 1: Discussion

    National Research Council Canada - National Science Library

    Cunningham, Atlee M

    1998-01-01

    ...) at low alpha conditions typical of transonic LCO flows with and without tip stores. Laser light sheet/water vapor techniques were used to illuminate the flows, and video recording was used to obtain the data...

  9. Analysis of Limit Cycle Oscillation/Transonic High ALPHA Flow Visualization. Part 2 Stationary Model Data

    National Research Council Canada - National Science Library

    Cunningham, Atlee M

    1998-01-01

    ...) at low alpha conditions typical of transonic LCO flows with and without tip stores. Laser light sheet/water vapor techniques were used to illuminate the flows, and video recording was used to obtain the data...

  10. Analysis of Limit Cycle Oscillation/Transonic High Alpha Flow Visualization

    National Research Council Canada - National Science Library

    Cunningham, Atlee M

    1997-01-01

    ...) at low alpha condition typical of transonic LCO flows with and without tip stores. Laser light sheet/water vapor techniques were used to illuminate the flows, and video recording was used to obtain the data...

  11. Analysis of Limit Cycle Oscillation/Transonic High ALPHA Flow Visualization. Part 3 Oscillating Model Data

    National Research Council Canada - National Science Library

    Cunningham, Atlee M

    1998-01-01

    ...) at low alpha conditions typical of transonic LCO flows with and without tip stores. Laser light sheet/water vapor techniques were used to illuminate the flows, and video recording was used to obtain the data...

  12. Axial annular flow of power-law fluids - applicability of the limiting cases

    Czech Academy of Sciences Publication Activity Database

    Filip, Petr; David, Jiří

    2007-01-01

    Roč. 52, č. 4 (2007), s. 365-371 ISSN 0001-7043 R&D Projects: GA ČR GA103/06/1033 Institutional research plan: CEZ:AV0Z20600510 Keywords : Concentric annuli * Poiseuile flow * annular flow * power- law fluids * flow rate * pressure drop Subject RIV: BK - Fluid Dynamics

  13. The Upper Limit of Cerebral Blood Flow Autoregulation Is Decreased with Elevations in Intracranial Pressure.

    Science.gov (United States)

    Pesek, Matthew; Kibler, Kathleen; Easley, R Blaine; Mytar, Jennifer; Rhee, Christopher; Andropolous, Dean; Brady, Ken

    2016-01-01

    The upper limit of cerebrovascular pressure autoregulation (ULA) is inadequately characterized. We sought to delineate the ULA in a neonatal swine model. Neonatal piglets with sham surgery (n = 9), interventricular fluid infusion (INF; n = 10), controlled cortical impact (CCI; n = 10), or impact + infusion (CCI + INF; n = 11) had intracranial pressure monitoring and bilateral cortical laser-Doppler flux recordings during arterial hypertension until lethality. An increase in red cell flux as a function of cerebral perfusion pressure was determined by piecewise linear regression and static rates of autoregulation (SRoRs) were determined above and below this inflection. When identified, the ULA (median [interquartile range]) was as follows: sham group: 102 mmHg (97-109), INF group: 75 mmHg (52-84), CCI group: 81 mmHg (69-101), and CCI + INF group: 61 mmHg (52-57; p = 0.01). Both groups with interventricular infusion had significantly lower ULA compared with the sham group. Neonatal piglets without intracranial pathological conditions tolerated acute hypertension, with minimal perturbation of cerebral blood flow. Piglets with acutely elevated intracranial pressure, with or without trauma, demonstrated loss of autoregulation when subjected to arterial hypertension.

  14. An expiratory assist during spontaneous breathing can compensate for endotracheal tube resistance.

    Science.gov (United States)

    Uchiyama, Akinori; Chang, Cheng; Suzuki, Shinya; Mashimo, Takashi; Fujino, Yuji

    2009-08-01

    Although inspiratory assist of spontaneous breathing in intubated patients is common, expiratory assist functions have rarely been reported. Effective expiratory support (ES) could be used to compensate for endotracheal tube (ETT) resistance during spontaneous breathing. In this study, we examined the performance of a new system designed to provide both inspiratory support (IS) and ES during spontaneous breathing with the goal of reducing the effective resistance of the ETT. The ES system consisted of a ventilator demand valve and a computer-controlled piston cylinder, which aspirated gas from the respiratory circuit during the expiratory phase. The movement of the piston was synchronized with spontaneous breathing. We compared the pressures at the tip of the ETT and in the breathing circuit during spontaneous breathing through an ETT of internal diameter (ID) 5 mm with that of an ETT with ID 8 mm in nine healthy adult male volunteers. The ventilatory mode was set to maintain a continuous airway pressure of 0 cm H(2)O. Three ventilator settings (no support, IS only, and IS plus ES) were compared using ID 5 mm ETT. We monitored pressure in the breathing circuit (P(aw)), ETT tip pressure (P(tip)), and respiratory flow. The P(tip) of the ID 5 mm ETT showed a large negative deflection during inspiration and a positive deflection during expiration without support. IS alone did not improve the respiratory pattern through the small ETT. However, IS plus ES resulted in negative P(aw) during expiration in addition to positive deflection of P(aw) during inspiration, making the pressure characteristics of P(tip) similar to those of ID 8 mm ETT. Moreover, IS plus ES produced a respiratory pattern through the ID 5 mm ETT that was similar to that through the ID 8 mm ETT. In this study of healthy volunteers, IS plus ES compensated for the airway resistance imposed by a ID 5.0 mm ETT to create pressure changes at the tip of the ETT similar to those of an ID 8.0 mm ETT.

  15. End expiratory oxygen concentrations to predict central venous oxygen saturation: an observational pilot study

    Directory of Open Access Journals (Sweden)

    Steuerwald Michael

    2006-09-01

    Full Text Available Abstract Background A non-invasive surrogate measurement for central venous oxygen saturation (ScVO2 would be useful in the ED for assessing therapeutic interventions in critically ill patients. We hypothesized that either linear or nonlinear mathematical manipulation of the partial pressure of oxygen in breath at end expiration (EtO2 would accurately predict ScVO2. Methods Prospective observational study of a convenience sample of hemodialysis patients age > 17 years with existing upper extremity central venous catheters were enrolled. Using a portable respiratory device, we collected both tidal breathing and end expiratory oxygen and carbon dioxide concentrations, volume and flow on each patient. Simultaneous ScVO2 measurements were obtained via blood samples collected from the hemodialysis catheter. Two models were used to predict ScVO2: 1 Best-fit multivariate linear regression equation incorporating all respiratory variables; 2 MathCAD to model the decay curve of EtO2 versus expiratory volume using the least squares method to estimate the pO2 that would occur at Results From 21 patients, the correlation between EtO2 and measured ScVO2 yielded R2 = 0.11. The best fit multivariate equation included EtCO2 and EtO2 and when solved for ScVO2, the equation yielded a mean absolute difference from the measured ScVO2 of 8 ± 6% (range -18 to +17%. The predicted ScVO2 value was within 10% of the actual value for 57% of the patients. Modeling of the EtO2 curve did not accurately predict ScVO2 at any lung volume. Conclusion We found no significant correlation between EtO2 and ScVO2. A linear equation incorporating EtCO2 and EtO2 had at best modest predictive accuracy for ScVO2.

  16. Effects of positive end-expiratory pressure on the sigmoid equation in experimental acute lung injury.

    Science.gov (United States)

    Bayle, Frederique; Guerin, Claude; Viale, Jean-Paul; Richard, Jean-Christophe; Annat, Guy

    2004-11-01

    To describe inflation and deflation volume-pressure (V-P) curves of the respiratory system by the sigmoidal equation at different levels of positive end-expiratory pressure (PEEP) in acute lung injury. Experimental study. Physiological laboratory in a university setting. Six pigs of 25 kg each. Acute lung injury was induced by oleic acid. PEEP was applied from 0 to 15 cm H(2)O and from 15 to 0 cm H(2)O for 10 min in steps of 5 cmH(2)O. Inflation and deflation V-P curves were constructed from an automated super-syringe that delivers a constant flow of 7 l/min in both inspiratory and expiratory directions. V-P curves were obtained at each level of PEEP without disconnecting the animal from the ventilator. The experimental data were fitted to the sigmoid equation which provided the true inflection point (c), the point of maximal compliance increase (Pmci) reflecting opening/closure and the point of maximal compliance decrease (Pmcd) reflecting end of recruitment/onset of de-recruitment. The sigmoid equation provided an excellent fit. The values of the coefficients of determination were greater than 0.970 (median 0.996, IQR 0.994-0.997 for the 84 determinations). Negative values of Pmci in the deflation limb of the V-P curve were recorded in five pigs, suggesting closure below the volume range studied. Inflation and deflation V-P curves at different PEEPs can be fitted by the sigmoid equation. However, further work is needed to investigate the meaning of negative values for Pmci.

  17. MOLECULAR METHODS USED TO ASSESS THE RISKS OF TRANSGENE FLOW; BENEFITS AND LIMITATIONS

    Science.gov (United States)

    The US EPA WED has initiated a gene flow project to characterize ecological risks of gene flow from GM plants to native species. Development of molecular assays for risk characterization down to gene expression level is of high interest to the EPA. Phylogenetic analyses of ampl...

  18. Effect of Flow Direction on the Extinction Limit for Flame Spread over Wire Insulation in Microgravity

    DEFF Research Database (Denmark)

    Nagachi, Masashi; Mitsui, Fumiya; Citerne, Jean-Marie

    and polyethylene insulated Nickel-Chrome (NiCr) wires with inner core diameter of 0.50 mm and insulation thickness of 0.30 mm were examined with external flow velocities ranging from 50mm/s to 200mm/s. The results for the Copper wires show that with increasing external flow velocity, the LOC monotonically...

  19. Pollination of pima pineapple cactus (Coryphantha sheeri var. robustispina): does pollen flow limit abundance of this endangered species?

    Science.gov (United States)

    Christopher J. McDonald; Guy R. McPherson

    2005-01-01

    Pima pineapple cactus (PPC) (Coryphantha sheeri var. robustispina), a federally listed endangered species, occurs throughout southeastern Arizona and has relatively low population densities. To determine whether pollination limits reproduction of PPC we used florescent dye to quantify pollen flow between individuals in a PPC...

  20. Control of abdominal and expiratory intercostal muscle activity during vomiting - Role of ventral respiratory group expiratory neurons

    Science.gov (United States)

    Miller, Alan D.; Tan, L. K.; Suzuki, Ichiro

    1987-01-01

    The role of ventral respiratory group (VRG) expiratory (E) neurons in the control of abdominal and internal intercostal muscle activity during vomiting was investigated in cats. Two series of experiments were performed: in one, the activity of VRG E neurons was recorded during fictive vomiting in cats that were decerebrated, paralyzed, and artificially ventilated; in the second, the abdominal muscle activity during vomiting was compared before and after sectioning the axons of descending VRG E neurons in decerebrate spontaneously breathing cats. The results show that about two-thirds of VRG E neurons that project at least as far caudally as the lower thoracic cord contribute to internal intercostal muscle activity during vomiting. The remaining VRG E neurons contribute to abdominal muscle activation. As shown by severing the axons of the VRG E neurons, other, as yet unidenified, inputs (either descending from the brain stem or arising from spinal reflexes) can also produce abdominal muscle activation.

  1. Expiratory and expiratory plus inspiratory muscle training improves respiratory muscle strength in subjects with COPD: systematic review.

    Science.gov (United States)

    Neves, Leonardo F; Reis, Manoela H; Plentz, Rodrigo D M; Matte, Darlan L; Coronel, Christian C; Sbruzzi, Graciele

    2014-09-01

    Inspiratory muscle training (IMT) produces beneficial effects in COPD subjects, but the effects of expiratory muscle training (EMT) and EMT plus IMT in ventilatory training are still unclear. The aim of this study was to systematically review the effects of EMT and EMT plus IMT compared to control groups of COPD subjects. This study is a systematic review and meta-analysis. The search strategy included MEDLINE, Embase, LILACS, PEDro, and Cochrane CENTRAL and also manual search of references in published studies on the subject. Randomized trials comparing EMT and EMT plus IMT versus control groups of subjects with COPD were included. The outcomes analyzed were respiratory muscle strength and functional capacity. Two reviewers independently extracted the data. The search retrieved 609 articles. Five studies were included. We observed that EMT provided higher gain in maximum expiratory pressure (P(E(max)) 21.49 cm H2O, 95% CI 13.39-29.59) and maximum inspiratory pressure (P(I(max)) 7.68 cm H2O, 95% CI 0.90-14.45) compared to control groups. There was no significant difference in the 6-min walk test distance (29.01 m, 95% CI -39.62 to 97.65) and dyspnea (0.15, 95% CI -0.77 to 1.08). In relation to EMT plus IMT, we observed that P(E(max)) (31.98 cm H2O, 95% CI 26.93-37.03) and P(I(max)) (27.98 cm H2O, 95% CI 20.10-35.85) presented higher values compared to control groups. EMT and EMT plus IMT improve respiratory muscle strength and can be used as part of the treatment during pulmonary rehabilitation of subjects with severe to very severe COPD. Copyright © 2014 by Daedalus Enterprises.

  2. Parameters affecting the tidal volume during expiratory abdominal compression in patients with prolonged tracheostomy mechanical ventilation.

    Science.gov (United States)

    Morino, Akira; Shida, Masahiro; Tanaka, Masashi; Sato, Kimihiro; Seko, Toshiaki; Ito, Shunsuke; Ogawa, Shunichi; Takahashi, Naoaki

    2015-07-01

    [Purpose] The aim of this study was to clarify physical parameters affecting the tidal volume during expiratory abdominal compression in patients with prolonged tracheostomy mechanical ventilation. [Methods] Eighteen patients with prolonged mechanical ventilation were included in this study. Expiratory abdominal compression was performed on patients lying in a supine position. The abdomen above the navel was vertically compressed in synchronization with expiration and released with inspiration. We measured the tidal volume during expiratory abdominal compression. [Results] The mean tidal volume during expiratory abdominal compression was higher than that at rest (430.6 ± 127.1 mL vs. 344.0 ± 94.3 mL). The tidal volume during expiratory abdominal compression was correlated with weight, days of ventilator support, dynamic compliance and abdominal expansion. Stepwise multiple regression analysis revealed that weight (β = 0.499), dynamic compliance (β = 0.387), and abdominal expansion (β = 0.365) were factors contributing to the tidal volume during expiratory abdominal compression. [Conclusion] Expiratory abdominal compression increased the tidal volume in patients with prolonged tracheostomy mechanical ventilation. The tidal volume during expiratory abdominal compression was influenced by each of the pulmonary conditions and the physical characteristics.

  3. The effect of positive end-expiratory pressure on pulse pressure ...

    African Journals Online (AJOL)

    The effect of positive end-expiratory pressure on pulse pressure variation. FJ Smith, M Geyser, I Schreuder, PJ Becker. Abstract. Objectives: To determine the effect of different levels of positive end-expiratory pressure (PEEP) on pulse pressure variation (PPV). Design: An observational study. Setting: Operating theatres of a ...

  4. Granular flows at recurring slope lineae on Mars indicate a limited role for liquid water

    Science.gov (United States)

    Dundas, Colin M.; McEwen, Alfred S.; Chojnacki, Matthew; Milazzo, Moses P.; Byrne, Shane; McElwaine, Jim N.; Urso, Anna

    2017-12-01

    Recent liquid water flow on Mars has been proposed based on geomorphological features, such as gullies. Recurring slope lineae — seasonal flows that are darker than their surroundings — are candidate locations for seeping liquid water on Mars today, but their formation mechanism remains unclear. Topographical analysis shows that the terminal slopes of recurring slope lineae match the stopping angle for granular flows of cohesionless sand in active Martian aeolian dunes. In Eos Chasma, linea lengths vary widely and are longer where there are more extensive angle-of-repose slopes, inconsistent with models for water sources. These observations suggest that recurring slope lineae are granular flows. The preference for warm seasons and the detection of hydrated salts are consistent with some role for water in their initiation. However, liquid water volumes may be small or zero, alleviating planetary protection concerns about habitable environments.

  5. Scaling up ecohydrological processes: role of surface water flow in water-limited landscapes

    CSIR Research Space (South Africa)

    Popp, A

    2009-11-01

    Full Text Available microscale processes like ecohydrological feedback mechanisms and spatial exchange like surface water flow, the authors derive transition probabilities from a fine-scale simulation model. They applied two versions of the landscape model, one that includes...

  6. Two-phase flow experiments on Counter-Current Flow Limitation in a model of the hot leg of a pressurized water reactor (2015 test series)

    Energy Technology Data Exchange (ETDEWEB)

    Beyer, Matthias; Lucas, Dirk; Pietruske, Heiko; Szalinski, Lutz

    2016-12-15

    Counter-Current Flow Limitation (CCFL) is of importance for PWR safety analyses in several accident scenarios connected with loss of coolant. Basing on the experiences obtained during a first series of hot leg tests now new experiments on counter-current flow limitation were conducted in the TOPFLOW pressure vessel. The test series comprises air-water tests at 1 and 2 bar as well as steam-water tests at 10, 25 and 50 bar. During the experiments the flow structure was observed along the hot leg model using a high-speed camera and web-cams. In addition pressure was measured at several positions along the horizontal part and the water levels in the reactor-simulator and steam-generator-simulator tanks were determined. This report documents the experimental setup including the description of operational and special measuring techniques, the experimental procedure and the data obtained. From these data flooding curves were obtained basing on the Wallis parameter. The results show a slight shift of the curves in dependency of the pressure. In addition a slight decrease of the slope was found with increasing pressure. Additional investigations concern the effects of hysteresis and the frequencies of liquid slugs. The latter ones show a dependency on pressure and the mass flow rate of the injected water. The data are available for CFD-model development and validation.

  7. Two-phase flow experiments on Counter-Current Flow Limitation in a model of the hot leg of a pressurized water reactor (2015 test series)

    International Nuclear Information System (INIS)

    Beyer, Matthias; Lucas, Dirk; Pietruske, Heiko; Szalinski, Lutz

    2016-12-01

    Counter-Current Flow Limitation (CCFL) is of importance for PWR safety analyses in several accident scenarios connected with loss of coolant. Basing on the experiences obtained during a first series of hot leg tests now new experiments on counter-current flow limitation were conducted in the TOPFLOW pressure vessel. The test series comprises air-water tests at 1 and 2 bar as well as steam-water tests at 10, 25 and 50 bar. During the experiments the flow structure was observed along the hot leg model using a high-speed camera and web-cams. In addition pressure was measured at several positions along the horizontal part and the water levels in the reactor-simulator and steam-generator-simulator tanks were determined. This report documents the experimental setup including the description of operational and special measuring techniques, the experimental procedure and the data obtained. From these data flooding curves were obtained basing on the Wallis parameter. The results show a slight shift of the curves in dependency of the pressure. In addition a slight decrease of the slope was found with increasing pressure. Additional investigations concern the effects of hysteresis and the frequencies of liquid slugs. The latter ones show a dependency on pressure and the mass flow rate of the injected water. The data are available for CFD-model development and validation.

  8. The evolution of sensory divergence in the context of limited gene flow in the bumblebee bat

    OpenAIRE

    Puechmaille, S?bastien J.; Gouilh, Meriadeg Ar; Piyapan, Piyathip; Yokubol, Medhi; Mie, Khin Mie; Bates, Paul J.; Satasook, Chutamas; Nwe, Tin; Bu, Si Si Hla; Mackie, Iain J.; Petit, Eric J.; Teeling, Emma C.

    2011-01-01

    The sensory drive theory of speciation predicts that populations of the same species inhabiting different environments can differ in sensory traits, and that this sensory difference can ultimately drive speciation. However, even in the best-known examples of sensory ecology driven speciation, it is uncertain whether the variation in sensory traits is the cause or the consequence of a reduction in levels of gene flow. Here we show strong genetic differentiation, no gene flow and large echoloca...

  9. Effects of posture on flow-volume curves during normocapnia and hypercapnia in patients with obstructive sleep apnoea.

    OpenAIRE

    Miura, C; Hida, W; Miki, H; Kikuchi, Y; Chonan, T; Takishima, T

    1992-01-01

    BACKGROUND: A high ratio of forced expiratory to forced inspiratory maximal flow at 50% of vital capacity (FEF50/FIF50) may identify upper airway dysfunction. Since hypercapnia increases the motor activity of airway dilating muscles its effects on the maximum expiratory and inspiratory flow-volume curves (MEIFV) in patients with obstructive sleep apnoea and in normal subjects in different postures was studied. METHODS: The effects of posture on the maximum expiratory and inspiratory flow-volu...

  10. Short hypobaric hypoxia and breathing pattern: effect of positive end expiratory pressure.

    Science.gov (United States)

    Savourey, G; Besnard, Y; Launay, J C; Guinet, A; Hanniquet, A M; Caterini, R; Bittel, J

    1999-09-01

    The ventilatory effects of a 5-cm H2O positive end expiratory pressure (PEEP) and its influence on the breathing pattern during short hypoxic exposure both at rest and during physical exercise were studied. There were 22 healthy subjects who were submitted to normoxia and to 4-h of hypoxia in a hypobaric chamber (4500 m, PB = 589 hPa) both at rest and during an 8-min cycle ergometer exercise (100 W) without and with a 5 cm H2O PEEP. The results show that hypoxia compared with normoxia induces increases in tidal volume (VT) (+28.5%, p breathing pattern expressed as duty cycle (tI/tt) is unchanged, whereas an increased mean inspiratory flow (VT/tI) is observed (p hypoxia significantly increases VT (+22.2% p breathing pattern in hypoxia since VT/tI and tI/tt are unchanged. Heart rate and arterial O2 saturation are also unaffected by PEEP. In conclusion, this study shows that a 4-h hypoxia modifies ventilatory parameters and mean inspiratory flow (VT/tI) at rest and during exercise (100 W), whereas a 5-cm H2O PEEP does not alter the breathing pattern despite changes in ventilatory parameters are observed.

  11. Performance of intact and partially degraded concrete barriers in limiting fluid flow

    International Nuclear Information System (INIS)

    Walton, J.C.; Seitz, R.R.

    1991-07-01

    Concrete barriers will play a critical role in the long-term isolation of low-level radioactive wastes. Over time the barriers will degrade, and in many cases, the fundamental processes controlling performance of the barriers will be different for intact and degraded conditions. This document examines factors controlling fluid flow through intact and degraded concrete disposal facilities. Simplified models are presented fro predicting build up of fluid above a vault; fluid flow through and around intact vaults, through flaws in coatings/liners applied to a vault, and through cracks in a concrete vault; and the influence of different backfill materials around the outside of the vault. Example calculations are presented to illustrate the parameters and processes that influence fluid flow. 46 refs., 49 figs., 2 tabs

  12. Upper limit of cerebral blood flow autoregulation in experimental renovascular hypertension in the baboon

    DEFF Research Database (Denmark)

    Strandgaard, S; Jones, J V; MacKenzie, E T

    1975-01-01

    The effect of arterial hypertension on cerebral blood flow was studied by the intracarotid 133Xe clearance method in baboons. The arterial blood pressure was raised in gradual steps with angiotensin. Baboons with renal hypertension of 8-12 weeks duration were studied along with normotensive baboo...

  13. Limitations to upscaling of groundwater flow models dominated by surface water interaction

    NARCIS (Netherlands)

    Vermeulen, P.T.M.; Te Stroet, C.B.M.; Heemink, A.W.

    2006-01-01

    Different upscaling methods for groundwater flow models are investigated. A suite of different upscaling methods is applied to several synthetic cases with structured and unstructured porous media. Although each of the methods applies best to one of the synthetic cases, no performance differences

  14. Low blood flow at onset of moderate-intensity exercise does not limit muscle oxygen uptake

    DEFF Research Database (Denmark)

    Nyberg, Michael Permin; Mortensen, Stefan P; Saltin, Bengt

    2010-01-01

    The effect of low blood flow at onset of moderate-intensity exercise on the rate of rise in muscle oxygen uptake was examined. Seven male subjects performed a 3.5-min one-legged knee-extensor exercise bout (24 +/- 1 W, mean +/- SD) without (Con) and with (double blockade; DB) arterial infusion of...... of exercise. Additionally, prostanoids and/or nitric oxide appear to play important roles in elevating skeletal muscle blood flow in the initial phase of exercise.......The effect of low blood flow at onset of moderate-intensity exercise on the rate of rise in muscle oxygen uptake was examined. Seven male subjects performed a 3.5-min one-legged knee-extensor exercise bout (24 +/- 1 W, mean +/- SD) without (Con) and with (double blockade; DB) arterial infusion...... of inhibitors of nitric oxide synthase (N(G)-monomethyl-l-arginine) and cyclooxygenase (indomethacin) to inhibit the synthesis of nitric oxide and prostanoids, respectively. Leg blood flow and leg oxygen delivery throughout exercise was 25-50% lower (P

  15. Low blood flow at onset of moderate intensity exercise does not limit muscle oxygen uptake

    DEFF Research Database (Denmark)

    Nyberg, Michael Permin; Mortensen, Stefan Peter; Saltin, Bengt

    2010-01-01

    The effect of low blood flow at onset of moderate intensity exercise on the rate of rise in muscle oxygen uptake was examined. Seven male subjects performed a 3.5 minute one-legged knee-extensor exercise bout (24+/-1 (+/-S.D.) W) without (CON) and with (double blockade; DB) arterial infusion of i....... Additionally, prostanoids and/or NO appear to play important roles in elevating skeletal muscle blood flow in the initial phase of exercise. Key words: Oxygen delivery, oxygen extraction, nitric oxide, prostanoids.......The effect of low blood flow at onset of moderate intensity exercise on the rate of rise in muscle oxygen uptake was examined. Seven male subjects performed a 3.5 minute one-legged knee-extensor exercise bout (24+/-1 (+/-S.D.) W) without (CON) and with (double blockade; DB) arterial infusion...... of inhibitors of nitric oxide synthase (NOS; L-NMMA) and cyclooxygenase (COX; indomethacin) in order to inhibit the synthesis of nitric oxide (NO) and prostanoids, respectively.. Leg blood flow and leg oxygen delivery throughout exercise was 25-50 % lower (P

  16. A tool to estimate bar patterns and flow conditions in estuaries when limited data is available

    Science.gov (United States)

    Leuven, J.; Verhoeve, S.; Bruijns, A. J.; Selakovic, S.; van Dijk, W. M.; Kleinhans, M. G.

    2017-12-01

    The effects of human interventions, natural evolution of estuaries and rising sea-level on food security and flood safety are largely unknown. In addition, ecologists require quantified habitat area to study future evolution of estuaries, but they lack predictive capability of bathymetry and hydrodynamics. For example, crucial input required for ecological models are values of intertidal area, inundation time, peak flow velocities and salinity. While numerical models can reproduce these spatial patterns, their computational times are long and for each case a new model must be developed. Therefore, we developed a comprehensive set of relations that accurately predict the hydrodynamics and the patterns of channels and bars, using a combination of the empirical relations derived from approximately 50 estuaries and theory for bars and estuaries. The first step is to predict local tidal prisms, which is the tidal prism that flows through a given cross-section. Second, the channel geometry is predicted from tidal prism and hydraulic geometry relations. Subsequently, typical flow velocities can be estimated from the channel geometry and tidal prism. Then, an ideal estuary shape is fitted to the measured planform: the deviation from the ideal shape, which is defined as the excess width, gives a measure of the locations where tidal bars form and their summed width (Leuven et al., 2017). From excess width, typical hypsometries can be predicted per cross-section. In the last step, flow velocities are calculated for the full range of occurring depths and salinity is calculated based on the estuary shape. Here, we will present a prototype tool that predicts equilibrium bar patterns and typical flow conditions. The tool is easy to use because the only input required is the estuary outline and tidal amplitude. Therefore it can be used by policy makers and researchers from multiple disciplines, such as ecologists, geologists and hydrologists, for example for paleogeographic

  17. Overcoming the acoustic diffraction limit in photoacoustic imaging by the localization of flowing absorbers.

    Science.gov (United States)

    Vilov, Sergey; Arnal, Bastien; Bossy, Emmanuel

    2017-11-01

    The resolution of photoacoustic imaging deep inside scattering media is limited by the acoustic diffraction limit. In this Letter, taking inspiration from super-resolution imaging techniques developed to beat the optical diffraction limit, we demonstrate that the localization of individual optical absorbers can provide super-resolution photoacoustic imaging well beyond the acoustic diffraction limit. As a proof-of-principle experiment, photoacoustic cross-sectional images of microfluidic channels were obtained with a 15 MHz linear capacitive micromachined ultrasonic transducer array, while absorbing beads were flown through the channels. The localization of individual absorbers allowed us to obtain a super-resolved cross-sectional image of the channels by reconstructing both the channel width and position with an accuracy better than λ/10. Given the discrete nature of endogenous absorbers such as red blood cells, or that of exogenous particular contrast agents, localization is a promising approach to push the current resolution limits of photoacoustic imaging.

  18. Proposal Intensity Adequacy of Expiratory Effort and Heart Rate Behavior During the Valsalva Maneuver in Preadolescents

    Directory of Open Access Journals (Sweden)

    Mario Augusto Paschoal

    2014-08-01

    Full Text Available Background: When performing the Valsalva maneuver (VM, adults and preadolescents produce the same expiratory resistance values. Objective: To analyze heart rate (HR in preadolescents performing VM, and propose a new method for selecting expiratory resistance. Method: The maximal expiratory pressure (MEP was measured in 45 sedentary children aged 9-12 years who subsequently performed VM for 20 s using an expiratory pressure of 60%, 70%, or 80% of MEP. HR was measured before, during, and after VM. These procedures were repeated 30 days later, and the data collected in the sessions (E1, E2 were analyzed and compared in periods before, during (0-10 and 10-20 s, and after VM using nonparametric tests. Results: All 45 participants adequately performed VM in E1 and E2 at 60% of MEP. However, only 38 (84.4% and 25 (55.5% of the participants performed the maneuver at 70% and 80% of MEP, respectively. The HR delta measured during 0-10 s and 10-20 s significantly increased as the expiratory effort increased, indicating an effective cardiac autonomic response during VM. However, our findings suggest the VM should not be performed at these intensities. Conclusion: HR increased with all effort intensities tested during VM. However, 60% of MEP was the only level of expiratory resistance that all participants could use to perform VM. Therefore, 60% of MEP may be the optimal expiratory resistance that should be used in clinical practice.

  19. Blood flow and vascular reactivity during attacks of classic migraine--limitations of the Xe-133 intraarterial technique

    International Nuclear Information System (INIS)

    Skyhoj Olsen, T.; Lassen, N.A.

    1989-01-01

    The present study reports cerebral blood flow (CBF) measurements in 11 patients during attacks of classic migraine (CM)--migraine with aura. In 6 and 7 patients, respectively, cerebral vascular reactivity to increased blood pressure and to hypocapnia was also investigated during the CM attacks. The Xenon-133 intraarterial injection technique was used to measure CBF. In this study, based in part on previously published data, methodological limitations, in particular caused by scattered radiation (Compton scatter), are critically analysed. Based on this analysis and the results of the CBF studies it is concluded: During CM attacks CBF appears to decrease focally in the posterior part of the brain to a level around 20 ml/100 g/min which is consistent with a mild degree of ischemia. Changes of CBF in focal low flow areas are difficult to evaluate accurately with the Xe-133 technique. In most cases true CBF may change 50% or more in the low flow areas without giving rise to significantly measurable changes of CBF. This analysis suggests that the autoregulation response cannot be evaluated in the low flow areas with the technique used while the observations are compatible with the concept that a vasoconstrictive state, unresponsive to hypocapnia, prevails in the low flow areas during CM attacks. The gradual increase in size of the low flow area seen in several cases may be interpreted in two different ways. A spreading process may actually exist. However, due to Compton scatter, a gradual decrease of CBF in a territory that does not increase in size will also appear as a gradually spreading low flow area when studied with the Xe-133 intracarotid technique

  20. Limitations to upscaling of groundwater flow models dominated by surface water interaction

    OpenAIRE

    Vermeulen, P.T.M.; Te Stroet, C.B.M.; Heemink, A.W.

    2006-01-01

    Different upscaling methods for groundwater flow models are investigated. A suite of different upscaling methods is applied to several synthetic cases with structured and unstructured porous media. Although each of the methods applies best to one of the synthetic cases, no performance differences are formed if the methods were applied to a real three-dimensional case. Furthermore, we focus on boundary conditions, such as Dirichlet, Neumann, and Cauchy conditions, that characterize the interac...

  1. Empirical analysis of gross vehicle weight and free flow speed and consideration on its relation with differential speed limit.

    Science.gov (United States)

    Saifizul, Ahmad Abdullah; Yamanaka, Hideo; Karim, Mohamed Rehan

    2011-05-01

    Most highly motorized countries in the world have implemented different speed limits for light weight and heavy weight vehicles. The heavy vehicle speed limit is usually chosen to be lower than that of passenger cars due to the difficulty for the drivers to safely maneuver the heavy vehicle at high speed and greater impact during a crash. However, in many cases, the speed limit for heavy vehicle is set by only considering the vehicle size or category, mostly due to simplicity in enforcement. In this study, traffic and vehicular data for all vehicle types were collected using a weigh-in-motion system installed at Federal Route 54 in Malaysia. The first finding from the data showed that the weight variation for each vehicle category is considerable. Therefore, the effect of gross vehicle weight (GVW) and category of heavy vehicle on free flow speed and their interaction were analyzed using statistical techniques. Empirical analysis results showed that statistically for each type of heavy vehicle, there was a significant relationship between free flow speed of a heavy vehicle and GVW. Specifically, the results suggest that the mean and variance of free flow speed decrease with an increase GVW by the amount unrelated to size and shape for all GVW range. Then, based on the 85th percentile principle, the study proposed a new concept for setting the speed limit for heavy vehicle by incorporating GVW where a different speed limit is imposed to the heavy vehicle, not only based on vehicle classification, but also according to its GVW. Copyright © 2010 Elsevier Ltd. All rights reserved.

  2. Electrochemical flow injection analysis of hydrazine in an excess of an active pharmaceutical ingredient: achieving pharmaceutical detection limits electrochemically.

    Science.gov (United States)

    Channon, Robert B; Joseph, Maxim B; Bitziou, Eleni; Bristow, Anthony W T; Ray, Andrew D; Macpherson, Julie V

    2015-10-06

    The quantification of genotoxic impurities (GIs) such as hydrazine (HZ) is of critical importance in the pharmaceutical industry in order to uphold drug safety. HZ is a particularly intractable GI and its detection represents a significant technical challenge. Here, we present, for the first time, the use of electrochemical analysis to achieve the required detection limits by the pharmaceutical industry for the detection of HZ in the presence of a large excess of a common active pharmaceutical ingredient (API), acetaminophen (ACM) which itself is redox active, typical of many APIs. A flow injection analysis approach with electrochemical detection (FIA-EC) is utilized, in conjunction with a coplanar boron doped diamond (BDD) microband electrode, insulated in an insulating diamond platform for durability and integrated into a two piece flow cell. In order to separate the electrochemical signature for HZ such that it is not obscured by that of the ACM (present in excess), the BDD electrode is functionalized with Pt nanoparticles (NPs) to significantly shift the half wave potential for HZ oxidation to less positive potentials. Microstereolithography was used to fabricate flow cells with defined hydrodynamics which minimize dispersion of the analyte and optimize detection sensitivity. Importantly, the Pt NPs were shown to be stable under flow, and a limit of detection of 64.5 nM or 0.274 ppm for HZ with respect to the ACM, present in excess, was achieved. This represents the first electrochemical approach which surpasses the required detection limits set by the pharmaceutical industry for HZ detection in the presence of an API and paves the wave for online analysis and application to other GI and API systems.

  3. Flow-through SIP - A novel stable isotope probing approach limiting cross-feeding

    Science.gov (United States)

    Mooshammer, Maria; Kitzinger, Katharina; Schintlmeister, Arno; Kjedal, Henrik; Nielsen, Jeppe Lund; Nielsen, Per; Wagner, Michael

    2017-04-01

    Stable isotope probing (SIP) is a widely applied tool to link specific microbial populations to metabolic processes in the environment without the prerequisite of cultivation, which has greatly advanced our understanding of the role of microorganisms in biogeochemical cycling. SIP relies on tracing specific isotopically labeled substrates (e.g., 13C, 15N, 18O) into cellular biomarkers, such as DNA, RNA or phospholipid fatty acids, and is considered to be a robust technique to identify microbial populations that assimilate the labeled substrate. However, cross-feeding can occur when labeled metabolites are released from a primary consumer and then used by other microorganisms. This leads to erroneous identification of organisms that are not directly responsible for the process of interest, but are rather connected to primary consumers via a microbial food web. Here, we introduce a new approach that has the potential to eliminate the effect of cross-feeding in SIP studies and can thus also be used to distinguish primary consumers from other members of microbial food webs. In this approach, a monolayer of microbial cells are placed on a filter membrane, and labeled substrates are supplied by a continuous flow. By means of flow-through, labeled metabolites and degradation products are constantly removed, preventing secondary consumption of the substrate. We present results from a proof-of-concept experiment using nitrifiers from activated sludge as model system, in which we used fluorescence in situ hybridization (FISH) with rRNA-targeted oligonucleotide probes for identification of nitrifiers in combination with nanoscale secondary ion mass spectrometry (NanoSIMS) for visualization of isotope incorporation at the single-cell level. Our results show that flow-through SIP is a promising approach to significantly reduce cross-feeding and secondary substrate consumption in SIP experiments.

  4. Efeitos da fisioterapia respiratória convencional versus aumento do fluxo expiratório na saturação de O2, freqüência cardíaca e freqüência respiratória, em prematuros no período pós-extubação Effects of conventional chest physical therapy versus increased expiratory flow on oxygen saturation, heart rate and respiratory rate in premature infants following extubation

    Directory of Open Access Journals (Sweden)

    LCO Antunes

    2006-01-01

    Full Text Available INTRODUÇÃO: Recém-nascidos (RN prematuros apresentam elevada morbidade respiratória e necessidade de ventilação mecânica, assim, a fisioterapia respiratória é parte integrante da assistência neonatal. Objetivo: Comparar os efeitos da fisioterapia respiratória convencional (FRC versus aumento do fluxo expiratório (AFE, na saturação de O2 (SpO2, freqüência cardíaca (FC e na freqüência respiratória (FR em prematuros no período pós-extubação. Método: Ensaio clínico randomizado realizado na UTI Neonatal do Hospital das Clínicas de BotucatuUNESP, comparando duas técnicas fisioterapêuticas, aplicadas em recém-nascidos prematuros, nas primeiras 48 horas pós-extubação. Para a análise estatística foram utilizados o teste t Student, Mann-Whitney, Qui-quadrado e o teste exato de Fisher, com nível de significância em 5%. Resultados: Os dois grupos de estudo: Grupo FRC (n= 20 e grupo AFE (n= 20, não diferiram quanto à idade gestacional (média de 28 semanas e peso de nascimento (média de 1100 gramas. Em ambos os grupos a síndrome do desconforto respiratório (SDR foi o principal diagnóstico. A mediana da idade no início da fisioterapia foi de sete dias no grupo AFE e 11 dias na FRC. Ambas as técnicas produziram aumento significativo da SpO2 aos 10 e 30 minutos, sem alterações na FR. A FC aumentou significativamente após a FRC e não se alterou após o AFE. Conclusão: Os resultados sugerem que o AFE é menos estressante que a FRC e pode ser aplicado em prematuros no período pós-extubação. Nestes recém-nascidos o AFE parece ser seguro e benéfico a curto prazo.Background: Respiratory morbidity and the need for mechanical ventilation are very high among preterm infants. Chest physical therapy is therefore an essential component of neonatal care. Objective: To compare the effects of conventional chest physical therapy (CCP and increased expiratory flow (IEF on the oxygen saturation (SpO2, heart rate, and

  5. Explosion and fire in the expiratory limb of a Fisher and Paykel "three in one" respiratory care system.

    Science.gov (United States)

    Gowardman, J R; Moriarty, B

    1998-08-01

    We report an incident involving a Fisher and Paykel "There in One Respiratory Care System" (Fisher and Paykel Healthcare, Auckland, New Zealand). This is a new ventilator circuit designed to be adaptable to the needs of ventilator, intubated CPAP, and mask therapies. In this case the patient had received eight hours of CPAP therapy overnight, during which time the "Three in One" circuit had been broken down to the CPAP configuration. The expiratory limb heater element, normally disconnected, was inadvertently left connected to the heater base. Under the extreme conditions of heating under "no gas flow" mode, the heater element malfunctioned. As a result when the circuit was reconfigured to provide pressure-supported ventilation, in the high oxygen environment of the expiratory limb (FiO2 0.5), ignition and combustion of the respiratory circuit occurred. The case is reported because of the potentially serious consequences and because the incident prompted the manufacturer to redesign and change componentry in parts of the circuit implicated.

  6. Radial space-charge-limited electron flow in semi-insulating GaN:Fe

    Czech Academy of Sciences Publication Activity Database

    Mareš, Jiří J.; Hubík, Pavel; Krištofik, Jozef; Prušáková, Lucie; Uxa, Štěpán; Paskova, T.; Evans, K.

    2011-01-01

    Roč. 110, č. 1 (2011), 013723/1-013723/6 ISSN 0021-8979 R&D Projects: GA ČR GAP204/10/0212 Institutional research plan: CEZ:AV0Z10100521 Keywords : gallium nitride * semi-insulator * space-charge-limited current Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.168, year: 2011

  7. Electronic cleansing for 24-h limited bowel preparation CT colonography using principal curvature flow

    NARCIS (Netherlands)

    van Ravesteijn, Vincent F.; Boellaard, Thierry N.; van der Paardt, Marije P.; Serlie, Iwo W. O.; de Haan, Margriet C.; Stoker, Jaap; van Vliet, Lucas J.; Vos, Frans M.

    2013-01-01

    CT colonography (CTC) is one of the recommended methods for colorectal cancer screening. The subject's preparation is one of the most burdensome aspects of CTC with a cathartic bowel preparation. Tagging of the bowel content with an oral contrast medium facilitates CTC with limited bowel

  8. Model predictive control for power flows in networks with limited capacity

    DEFF Research Database (Denmark)

    Biegel, Benjamin; Stoustrup, Jakob; Bendtsen, Jan Dimon

    2012-01-01

    We consider an interconnected network of consumers powered through an electrical grid of limited capacity. A subset of the consumers are intelligent consumers and have the ability to store energy in a controllable fashion; they can be filled and emptied as desired under power and capacity...... ensuring high performance....

  9. A single photon emission computed tomograph based on a limited dumber of detectors for fluid flow visualization

    International Nuclear Information System (INIS)

    Legoupil, S.

    1999-01-01

    We present in this work a method for fluid flow visualization in a system using radioactive tracers. The method is based on single photon emission computed tomography techniques, applied to a limited number of discrete detectors. We propose in this work a method for the estimation of the transport matrix of photons, associated to the acquisition system. This method is based on the modelization of profiles acquired for a set of point sources located in the imaged volume. Monte Carlo simulations allow to separate scattered photons from those directly collected by the system. The influence of the energy tracer is exposed. The reconstruction method is based on the maximum likelihood - expectation maximization algorithm. An experimental device, based on 36 detectors was realised for the visualization of water circulation in a vessel. A video monitoring allows to visualize the dye water tracer. Dye and radioactive tracers are injected simultaneously in a water flow circulating in the vessel. Reconstructed and video images are compared. Quantitative and qualitative analysis show that fluid flow visualization is feasible with a limited number of detectors. This method can be applied for system involving circulations of fluids. (author)

  10. EFFECT OF POSITIVE EXPIRATORY PRESSURE ON BREATHING PATTERN IN HEALTHY-SUBJECTS

    NARCIS (Netherlands)

    VANDERSCHANS, CP; DEJONG, W; DEVRIES, G; POSTMA, DS; KOETER, GH; VANDERMARK, TW

    The purpose of this study was to register breathing patterns, in healthy subjects, during breathing with a positive expiratory pressure. Integrated electromyographic (IEMG) activity of the following muscles was assessed: scalene muscle, parasternal muscle and abdominal muscles, using surface

  11. Discrete particle swarm optimization to solve multi-objective limited-wait hybrid flow shop scheduling problem

    Science.gov (United States)

    Santosa, B.; Siswanto, N.; Fiqihesa

    2018-04-01

    This paper proposes a discrete Particle Swam Optimization (PSO) to solve limited-wait hybrid flowshop scheduing problem with multi objectives. Flow shop schedulimg represents the condition when several machines are arranged in series and each job must be processed at each machine with same sequence. The objective functions are minimizing completion time (makespan), total tardiness time, and total machine idle time. Flow shop scheduling model always grows to cope with the real production system accurately. Since flow shop scheduling is a NP-Hard problem then the most suitable method to solve is metaheuristics. One of metaheuristics algorithm is Particle Swarm Optimization (PSO), an algorithm which is based on the behavior of a swarm. Originally, PSO was intended to solve continuous optimization problems. Since flow shop scheduling is a discrete optimization problem, then, we need to modify PSO to fit the problem. The modification is done by using probability transition matrix mechanism. While to handle multi objectives problem, we use Pareto Optimal (MPSO). The results of MPSO is better than the PSO because the MPSO solution set produced higher probability to find the optimal solution. Besides the MPSO solution set is closer to the optimal solution

  12. Flowing liquid lithium plasma-facing components – Physics, technology and system analysis of the LiMIT system

    Directory of Open Access Journals (Sweden)

    D.N. Ruzic

    2017-08-01

    Full Text Available The use of low atomic number liquid metals has been shown to have the potential to solve many of the prevalent problems like erosion and radiation losses associated with the interaction of fusion plasma with the plasma facing component (PFC structures in tokamaks. Since the first evidence of lithium increasing plasma performance in TFTR [1], the benefits of using lithium in fusion environments have been seen in many devices, including CDX-U [2], NSTX [3], LTX [4], and DIII-D [5]. While both fast flow and slow flow concepts have been studied with regards to liquid lithium first wall alternatives, this report will focus on efforts placed on fast flow research and will mainly focus on advancements in the LiMIT device that help to eliminate concerns over the broad use of liquid lithium. Due to the promising TFTR results along with results obtained at the University of Illinois at Urbana-Champaign [6], suitably designed trench structures holding liquid lithium could be an appropriate fast flow candidate for PFC modules in future fusion devices. There are four potential shortcomings of this approach: (1 Droplet ejection, (2 Wetting control, (3 Tritium retention, and (4 Limited heat flux handling. Droplet ejection is discussed in a companion publication [7], while this paper addresses the topics of wetting control and heat flux handling. Limitations in wetting and prevention of lithium creep (i.e. getting and keeping the lithium only where it should be have been solved by laser-texturing the base material with extreme short laser pulses (pico – femto second of high power (several 10s of W. Micro- and nano-structuring results indicate that the textured substrates displayed significant change in their wetting properties, increasing the temperature needed to wet from 310 °C to 390 °C. Lastly, initial designs for the Lithium Metal Infused Trenches (LiMIT [6] showed dryout above 3 MW/m2, but new designs of the trench shaping show potential to be

  13. Flow protection trip limits operational charge-discharge facility -- C Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Van Wormer, F.W.

    1958-09-19

    Because of wide variations in the venturi throat pressure, well beyond the panellit gage trip range, that occur during the sequence of operational charge-discharge, the panellit gage cannot be included in the scram safety circuit during the period of time that charge- discharge operations are being performed. In its stead, the function of the panellit gage is replaced in an overlapping manner by a tube inlet pressure monitor that is equipped with high and low pressure trip mechanisms that may be included in the scram safety circuit during the time that the panellit gage must be by-passed. The tube inlet pressure monitor is then used to provide the protection from unstable flow that is normally obtained with the panellit gage. This memorandum describes the manner in which the tube inlet pressure monitor trip points are to be determined and used.

  14. A continuous-flow periphyton bioassay: tests of nutrient limitation in a tundra stream

    International Nuclear Information System (INIS)

    Peterson, B.J.; Hobbie, J.E.; Corliss, T.L.; Kriet, K.

    1983-01-01

    The effect of added nutrients on the periphyton of a tundra stream was tested during July and August. Flow-through systems consisting of a bank of clear plastic tubes containing racks of microscope slides were suspended from floats in the stream. Nutrients were enriched in the experimental tubes by siphoning concentrated nutrient solutions from Mariotte bottles into the upstream end of each tube. Slides from each tube were assayed at 2-6 day intervals for chlorophyll content and photosynthetic 14 CO 2 uptake. Levels of chlorophyll and CO 2 uptake were significantly higher than the controls both in the tubes with 10μg PO 4 -P>liter -1 of stream water and in those with P plus 100 μg NH 4 NO 3 -N.liter. Nitrogen alone gave no stimulation

  15. Possible complication regarding phosphorus removal with a continuous flow biofilm system: Diffusion limitation

    DEFF Research Database (Denmark)

    Falkentoft, C.M.; Arnz, P.; Henze, Mogens

    2001-01-01

    Diffusion limitation of phosphate possibly constitutes a serious problem regarding the use of a biofilm reactor for enhanced biological phosphorus removal. A lab-scale reactor for simultaneous removal of phosphorus and nitrate was operated in a continuous alternating mode of operation. For a steady......-state operation with excess amounts of carbon source (acetate) during the anaerobic phase, the same amount of phosphate was released during the anaerobic phase as was taken up during the anoxic phase. The measured phosphorus content of the biomass that detached during backwash after an anoxic phase was low, 2.......4 ± 0.4% (equal to 24 ± 4 mg P/g TS). A simplified computer model indicated the reason to be phosphate diffusion limitation and the model revealed a delicate balance between the obtainable phosphorus contents of the biomass and operating parameters, such as backwash interval, biofilm thickness after...

  16. A note on 'A simple approach to search for all d-MCs of a limited-flow network'

    International Nuclear Information System (INIS)

    Salehi Fathabadi, H.; Forghani-elahabadi, M.

    2009-01-01

    Many real-world systems are multi-state systems composed of multi-state components in which the reliability can be computed in terms of the lower bound points of level d, called d-Mincuts (d-MCs). Such systems (electric power, transportation, etc.) may be considered as network flows whose arcs have independent and discrete random capacities. In this comment, we investigate the algorithm proposed by Yeh [A simple approach to search for all d-MCs of a limited-flow network. Reliability Engineering and System Safety 2001;71(1):15-19]. We show that the algorithm misses some real d-MCs, and then pinpoint the algorithm's failure and suggest the correcting point.

  17. Coronal rain in magnetic arcades: Rebound shocks, Limit cycles, and Shear flows

    OpenAIRE

    Fang, X.; Xia, C.; Keppens, R.; Van Doorsselaere, T.

    2015-01-01

    We extend our earlier multidimensional, magnetohydrodynamic simulations of coronal rain occurring in magnetic arcades with higher resolution, grid-adaptive computations covering a much longer ($>6$ hour) timespan. We quantify how in-situ forming blob-like condensations grow along and across field lines and show that rain showers can occur in limit cycles, here demonstrated for the first time in 2.5D setups. We discuss dynamical, multi-dimensional aspects of the rebound shocks generated by the...

  18. On the low Mach number limit of compressible flows in exterior moving domains

    Czech Academy of Sciences Publication Activity Database

    Feireisl, Eduard; Kreml, Ondřej; Mácha, Václav; Nečasová, Šárka

    2016-01-01

    Roč. 16, č. 3 (2016), s. 705-722 ISSN 1424-3199 R&D Projects: GA ČR GA13-00522S Institutional support: RVO:67985840 Keywords : compressible Navier - Stokes system * incompressible limit * moving domain Subject RIV: BA - General Mathematics Impact factor: 1.038, year: 2016 http://link.springer.com/article/10.1007%2Fs00028-016-0338-2

  19. Drag reduction by microbubbles in turbulent flows: the limit of minute bubbles.

    Science.gov (United States)

    L'vov, Victor S; Pomyalov, Anna; Procaccia, Itamar; Tiberkevich, Vasil

    2005-05-06

    Drag reduction by microbubbles is a promising engineering method for improving ship performance. A fundamental theory of the phenomenon is lacking, however, making actual design quite haphazard. We offer here a theory of drag reduction by microbubbles in the limit of very small bubbles, when the effect of the bubbles is mainly to normalize the density and the viscosity of the carrier fluid. The theory culminates with a prediction of the degree of drag reduction given the concentration profile of the bubbles. Comparisons with experiments are discussed and the road ahead is sketched.

  20. Linking skeletal muscle blood flow and metabolism to the limits of human performance.

    Science.gov (United States)

    Boushel, Robert

    2017-01-01

    Over the last 50 years, Bengt Saltin's contributions to our understanding of physiology of the circulation, the matching of the circulation to muscle metabolism, and the underlying mechanisms that set the limits for exercise performance were enormous. His research addressed the key questions in the field using sophisticated experimental methods including field expeditions. From the Dallas Bedrest Study to the 1-leg knee model to the physiology of lifelong training, his prodigious body of work was foundational in the field of exercise physiology and his leadership propelled integrative human physiology into the mainstream of biological sciences.

  1. Externally Phase-Locked Flux Flow Oscillator for Submm Integrated Receivers; Achievements and Limitations

    DEFF Research Database (Denmark)

    Koshelets, V. P.; Shitov, S. V.; Dmitriev, P. N.

    2003-01-01

    to 712 GHz, limited only by the gap frequency of Nb. This enabled us to phase lock the FFO in the frequency range 500-712 GHz where continuous frequency tuning is possible; resulting in an absolute FFO phase noise as low as -80 dBc at 707 GHz. Comprehensive measurements of the FFO radiation linewidth...... have been performed using an integrated SIS harmonic mixer. The influence of FFO parameters on radiation linewidth, particularly the effect of the differential resistances associated both with the bias current and the applied magnetic field has been studied in order to further optimize the FFO design...

  2. Natural history of optical coherence tomography-detected non-flow-limiting edge dissections following drug-eluting stent implantation

    DEFF Research Database (Denmark)

    Radu, Maria D; Räber, Lorenz; Heo, Jungho

    2014-01-01

    history and clinical implications remain unclear. The objectives of the present study were to assess the morphology, healing response, and clinical outcomes of OCT-detected edge dissections using serial OCT imaging at baseline and at one year following drug-eluting stent (DES) implantation. METHODS......, and clinical outcomes were assessed. Sixty-three lesions (57 patients) were studied with OCT at baseline and one-year follow-up. Twenty-two non-flow-limiting edge dissections in 21 lesions (20 patients) were identified by OCT; only two (9%) were angiographically visible. Flaps were found in 96% of cases...

  3. The limited and localized flow of fresh groundwater to the world's oceans

    Science.gov (United States)

    Luijendijk, E.; Gleeson, T. P.; Moosdorf, N.

    2017-12-01

    Submarine groundwater discharge, the flow of fresh or saline groundwater to oceans [Burnett et al., 2003], may be a significant contributor to the water and chemical budgets of the world's oceans [Taniguchi et al., 2002] potentially buffering ocean acidification with groundwater alkalinity and is arguably the most uncertain component of the global groundwater budget [Alley et al., 2002]. The fresh component of submarine groundwater discharge is critical due to its high solute and nutrient load, and has been quantified locally and but only roughly estimated globally using significant assumptions. Here we show that that fresh submarine groundwater discharge is an insignificant water contributor to global oceans (0.05% of the total input) but that the freshwater discharge may still be an important chemical and nutrient contributor especially around distinct hotspots. The first spatially-explicit, physically-based global estimate of fresh submarine groundwater discharge was derived by combining density-dependent numerical groundwater models and a geospatial analysis of global coastal watersheds to robustly simulate the partitioning of onshore and offshore groundwater discharge. Although fresh submarine groundwater discharge is an insignificant part of fresh coastal groundwater discharge, results are consistent with previous estimates of significant recirculated seawater discharging as groundwater as well as quantifying the significant near-shore terrestrial discharge, a flux that has so far been overlooked in global hydrological studies and that affects coastal water budgets, evapotranspiration and ecosystems.

  4. Peering below the diffraction limit: robust and specific sorting of viruses with flow cytometry.

    Science.gov (United States)

    Lance, Shea T; Sukovich, David J; Stedman, Kenneth M; Abate, Adam R

    2016-12-01

    Viruses are incredibly diverse organisms and impact all forms of life on Earth; however, individual virions are challenging to study due to their small size and mass, precluding almost all direct imaging or molecular analysis. Moreover, like microbes, the overwhelming majority of viruses cannot be cultured, impeding isolation, replication, and study of interesting new species. Here, we introduce PCR-activated virus sorting, a method to isolate specific viruses from a heterogeneous population. Specific sorting opens new avenues in the study of uncultivable viruses, including recovering the full genomes of viruses based on genetic fragments in metagenomes, or identifying the hosts of viruses. PAVS enables specific sorting of viruses with flow cytometry. A sample containing a virus population is processed through a microfluidic device to encapsulate it into droplets, such that the droplets contain different viruses from the sample. TaqMan PCR reagents are also included targeting specific virus species such that, upon thermal cycling, droplets containing the species become fluorescent. The target viruses are then recovered via droplet sorting. The recovered virus genomes can then be analyzed with qPCR and next generation sequencing. We describe the PAVS workflow and demonstrate its specificity for identifying target viruses in a heterogeneous population. In addition, we demonstrate recovery of the target viruses via droplet sorting and analysis of their nucleic acids with qPCR.

  5. An Assessment of Counter-current Flow Limitation Phenomena Using MARS Code

    Energy Technology Data Exchange (ETDEWEB)

    Huong, Phan Thi [Korea Institute Advance Science and Tehnology, Daejeon (Korea, Republic of); Chang, Won Joon; Cho, Yong Jin [Korea Institute of Nuclear Safety, Daejeon (Korea, Republic of)

    2013-10-15

    Wallis and Kutateladze who studied counter current of liquid-gas flow in vertically channel found the inversely proportional relationship of the liquid and gas velocity. There are a number of experimental models conducted over the years for flooding, or CCFL, that base on the different viewpoints on the initiation and the basic mechanism of flooding. However, according to development of computational technology, analysis is more convenient by using computational analysis, such as TRACE code. MARS code was developed by KAERI based on RELAP5/MOD3 and RELAP5 code adopted the simple CCFL model. Some studies had been performed to assess CCFL phenomenon using MARS. However, the CCFL assessments have not been extensively performed. In this paper, simple CCFL phenomena occurrences were investigated and further studies were suggested. The results of this paper show that MARS code can predict well the onset of CCFL: small pipe for Wallis correlation; large pipe for Kutateladze correlation at low pressure environment. However, to analysis CCFL phenomenon in real reactor geometry, further researches need be conducted at varied pressures to ensure that the MARS code predicts well the onset of CCFL in the high pressure - the actual condition of the reactor.

  6. Transpulmonary Pressure Describes Lung Morphology During Decremental Positive End-Expiratory Pressure Trials in Obesity.

    Science.gov (United States)

    Fumagalli, Jacopo; Berra, Lorenzo; Zhang, Changsheng; Pirrone, Massimiliano; Santiago, Roberta R De Santis; Gomes, Susimeire; Magni, Federico; Dos Santos, Glaucia A B; Bennett, Desmond; Torsani, Vinicius; Fisher, Daniel; Morais, Caio; Amato, Marcelo B P; Kacmarek, Robert M

    2017-08-01

    Atelectasis develops in critically ill obese patients when undergoing mechanical ventilation due to increased pleural pressure. The current study aimed to determine the relationship between transpulmonary pressure, lung mechanics, and lung morphology and to quantify the benefits of a decremental positive end-expiratory pressure trial preceded by a recruitment maneuver. Prospective, crossover, nonrandomized interventional study. Medical and Surgical Intensive Care Units at Massachusetts General Hospital (Boston, MA) and University Animal Research Laboratory (São Paulo, Brazil). Critically ill obese patients with acute respiratory failure and anesthetized swine. Clinical data from 16 mechanically ventilated critically ill obese patients were analyzed. An animal model of obesity with reversible atelectasis was developed by placing fluid filled bags on the abdomen to describe changes of lung mechanics, lung morphology, and pulmonary hemodynamics in 10 swine. In obese patients (body mass index, 48 ± 11 kg/m), 21.7 ± 3.7 cm H2O of positive end-expiratory pressure resulted in the lowest elastance of the respiratory system (18.6 ± 6.1 cm H2O/L) after a recruitment maneuver and decremental positive end-expiratory pressure and corresponded to a positive (2.1 ± 2.2 cm H2O) end-expiratory transpulmonary pressure. Ventilation at lowest elastance positive end-expiratory pressure preceded by a recruitment maneuver restored end-expiratory lung volume (30.4 ± 9.1 mL/kg ideal body weight) and oxygenation (273.4 ± 72.1 mm Hg). In the swine model, lung collapse and intratidal recruitment/derecruitment occurred when the positive end-expiratory transpulmonary pressure decreased below 2-4 cm H2O. After the development of atelectasis, a decremental positive end-expiratory pressure trial preceded by lung recruitment identified the positive end-expiratory pressure level (17.4 ± 2.1 cm H2O) needed to restore poorly and nonaerated lung tissue

  7. Power flow analysis and optimal locations of resistive type superconducting fault current limiters.

    Science.gov (United States)

    Zhang, Xiuchang; Ruiz, Harold S; Geng, Jianzhao; Shen, Boyang; Fu, Lin; Zhang, Heng; Coombs, Tim A

    2016-01-01

    Based on conventional approaches for the integration of resistive-type superconducting fault current limiters (SFCLs) on electric distribution networks, SFCL models largely rely on the insertion of a step or exponential resistance that is determined by a predefined quenching time. In this paper, we expand the scope of the aforementioned models by considering the actual behaviour of an SFCL in terms of the temperature dynamic power-law dependence between the electrical field and the current density, characteristic of high temperature superconductors. Our results are compared to the step-resistance models for the sake of discussion and clarity of the conclusions. Both SFCL models were integrated into a power system model built based on the UK power standard, to study the impact of these protection strategies on the performance of the overall electricity network. As a representative renewable energy source, a 90 MVA wind farm was considered for the simulations. Three fault conditions were simulated, and the figures for the fault current reduction predicted by both fault current limiting models have been compared in terms of multiple current measuring points and allocation strategies. Consequently, we have shown that the incorporation of the E - J characteristics and thermal properties of the superconductor at the simulation level of electric power systems, is crucial for estimations of reliability and determining the optimal locations of resistive type SFCLs in distributed power networks. Our results may help decision making by distribution network operators regarding investment and promotion of SFCL technologies, as it is possible to determine the maximum number of SFCLs necessary to protect against different fault conditions at multiple locations.

  8. Reduced-order aeroelastic model for limit-cycle oscillations in vortex-dominated unsteady airfoil flows

    Science.gov (United States)

    Suresh Babu, Arun Vishnu; Ramesh, Kiran; Gopalarathnam, Ashok

    2017-11-01

    In previous research, Ramesh et al. (JFM,2014) developed a low-order discrete vortex method for modeling unsteady airfoil flows with intermittent leading edge vortex (LEV) shedding using a leading edge suction parameter (LESP). LEV shedding is initiated using discrete vortices (DVs) whenever the Leading Edge Suction Parameter (LESP) exceeds a critical value. In subsequent research, the method was successfully employed by Ramesh et al. (JFS, 2015) to predict aeroelastic limit-cycle oscillations in airfoil flows dominated by intermittent LEV shedding. When applied to flows that require large number of time steps, the computational cost increases due to the increasing vortex count. In this research, we apply an amalgamation strategy to actively control the DV count, and thereby reduce simulation time. A pair each of LEVs and TEVs are amalgamated at every time step. The ideal pairs for amalgamation are identified based on the requirement that the flowfield in the vicinity of the airfoil is least affected (Spalart, 1988). Instead of placing the amalgamated vortex at the centroid, we place it at an optimal location to ensure that the leading-edge suction and the airfoil bound circulation are conserved. Results of the initial study are promising.

  9. Flux Limiter Lattice Boltzmann Scheme Approach to Compressible Flows with Flexible Specific-Heat Ratio and Prandtl Number

    International Nuclear Information System (INIS)

    Gan Yanbiao; Li Yingjun; Xu Aiguo; Zhang Guangcai

    2011-01-01

    We further develop the lattice Boltzmann (LB) model [Physica A 382 (2007) 502] for compressible flows from two aspects. Firstly, we modify the Bhatnagar-Gross-Krook (BGK) collision term in the LB equation, which makes the model suitable for simulating flows with different Prandtl numbers. Secondly, the flux limiter finite difference (FLFD) scheme is employed to calculate the convection term of the LB equation, which makes the unphysical oscillations at discontinuities be effectively suppressed and the numerical dissipations be significantly diminished. The proposed model is validated by recovering results of some well-known benchmarks, including (i) The thermal Couette flow; (ii) One- and two-dimensional Riemann problems. Good agreements are obtained between LB results and the exact ones or previously reported solutions. The flexibility, together with the high accuracy of the new model, endows the proposed model considerable potential for tracking some long-standing problems and for investigating nonlinear nonequilibrium complex systems. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  10. Level-set reconstruction algorithm for ultrafast limited-angle X-ray computed tomography of two-phase flows.

    Science.gov (United States)

    Bieberle, M; Hampel, U

    2015-06-13

    Tomographic image reconstruction is based on recovering an object distribution from its projections, which have been acquired from all angular views around the object. If the angular range is limited to less than 180° of parallel projections, typical reconstruction artefacts arise when using standard algorithms. To compensate for this, specialized algorithms using a priori information about the object need to be applied. The application behind this work is ultrafast limited-angle X-ray computed tomography of two-phase flows. Here, only a binary distribution of the two phases needs to be reconstructed, which reduces the complexity of the inverse problem. To solve it, a new reconstruction algorithm (LSR) based on the level-set method is proposed. It includes one force function term accounting for matching the projection data and one incorporating a curvature-dependent smoothing of the phase boundary. The algorithm has been validated using simulated as well as measured projections of known structures, and its performance has been compared to the algebraic reconstruction technique and a binary derivative of it. The validation as well as the application of the level-set reconstruction on a dynamic two-phase flow demonstrated its applicability and its advantages over other reconstruction algorithms. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

  11. Assessment of nitrogen and phosphorus flows in agricultural and urban systems in a small island under limited data availability.

    Science.gov (United States)

    Firmansyah, I; Spiller, M; de Ruijter, F J; Carsjens, G J; Zeeman, G

    2017-01-01

    Nitrogen (N) and phosphorus (P) are two essential macronutrients required in agricultural production. The major share of this production relies on chemical fertilizer that requires energy and relies on limited resources (P). Since these nutrients are lost to the environment, there is a need to shift from this linear urban metabolism to a circular metabolism in which N and P from domestic waste and wastewater are reused in agriculture. A first step to facilitate a transition to more circular urban N and P management is to understand the flows of these resources in a coupled urban-agricultural system. For the first time this paper presents a Substance Flow Analysis (SFA) approach for the assessment of the coupled agricultural and urban systems under limited data availability in a small island. The developed SFA approach is used to identify intervention points that can provide N and P stocks for agricultural production. The island of St. Eustatius, a small island in the Caribbean, was used as a case study. The model developed in this study consists of eight sub-systems: agricultural and natural lands, urban lands, crop production, animal production, market, household consumption, soakage pit and open-dump landfill. A total of 26 flows were identified and quantified for a period of one year (2013). The results showed that the agricultural system is a significant source for N and P loss because of erosion/run-off and leaching. Moreover, urban sanitation systems contribute to deterioration of the island's ecosystem through N and P losses from domestic waste and wastewater by leaching and atmospheric emission. Proposed interventions are the treatment of blackwater and greywater for the recovery of N and P. In conclusion, this study allows for identification of potential N and P losses and proposes mitigation measures to improve nutrient management in a small island context. Copyright © 2016 Elsevier B.V. All rights reserved.

  12. Effect of Supplementing Oxygen with Positive end Expiratory Pressure During Elective Caesarean Section under Spinal Anaesthesia on Foetus

    Science.gov (United States)

    Prabhu, Ramesh; Jayaraj; Shenoy, U Kailasanath

    2010-01-01

    Background: It is known fact that pre-oxygenation with positive end-expiratory pressure (PEEP) improves the Partial pressure of oxygen (PO 2). In this regard not many studies have been done in pregnant women to know its effect on foetus. In this randomised double blind controlled study, we analysed effect of pre-oxygenation with PEEP during caesarean section on foetal umbilical venous PO 2. Patients & Methods: 40 term pregnant women, ASA I or II, undergoing elective Caesarean section under spinal anaes-thesia were randomly divided into PEEP and Non-PEEP groups of 20 each. PEEP group received oxygen flow of 6 L/minute with PEEP of 5 cmH 2O using a modified Mapleson A circuit with fixed unidirectional PEEP valve at the expiratory port during pre-oxygenation and Non PEEP group received same fresh gas flow of oxygen using same breathing circuit without PEEP. Maternal arterial blood samples were collected before applying PEEP and at the end of 5 minutes of facemask application for oxygen analysis. Immediately after baby was delivered umbilical venous samples were taken for blood gas analysis. Results: Both groups were comparable in terms of maternal baseline oxygen saturation (Spo 2) and base line Po 2. After 5 minutes PO 2was higher in PEEP Group than non PEEP group (491.65 + 49.96 vs. 452.08 + 77.61). Umbilical venous Po 2in PEEP group was higher than non PEEP group (34.22 + 6.50 vs. 28.29 + 6.10 mm of Hg). Conclusion: Application of PEEP during pre-oxygenation for spinal anaesthesia can increase foetal umbilical venous PO2. PMID:21547172

  13. Current Flow and Pair Creation at Low Altitude in Rotation-Powered Pulsars' Force-Free Magnetospheres: Space Charge Limited Flow

    Science.gov (United States)

    Timokhin, A. N.; Arons, J.

    2013-01-01

    We report the results of an investigation of particle acceleration and electron-positron plasma generation at low altitude in the polar magnetic flux tubes of rotation-powered pulsars, when the stellar surface is free to emit whatever charges and currents are demanded by the force-free magnetosphere. We apply a new 1D hybrid plasma simulation code to the dynamical problem, using Particle-in-Cell methods for the dynamics of the charged particles, including a determination of the collective electrostatic fluctuations in the plasma, combined with a Monte Carlo treatment of the high-energy gamma-rays that mediate the formation of the electron-positron pairs.We assume the electric current flowing through the pair creation zone is fixed by the much higher inductance magnetosphere, and adopt the results of force-free magnetosphere models to provide the currents which must be carried by the accelerator. The models are spatially one dimensional, and designed to explore the physics, although of practical relevance to young, high-voltage pulsars. We observe novel behaviour (a) When the current density j is less than the Goldreich-Julian value (0 current carrying beam is mild, with the full Goldreich-Julian charge density comprising the charge densities of the beam and a cloud of electrically trapped particles with the same sign of charge as the beam. The voltage drops are of the order of mc(sup 2)/e, and pair creation is absent. (b) When the current density exceeds the Goldreich-Julian value (j/j(sub GJ) > 1), the system develops high voltage drops (TV or greater), causing emission of curvature gamma-rays and intense bursts of pair creation. The bursts exhibit limit cycle behaviour, with characteristic time-scales somewhat longer than the relativistic fly-by time over distances comparable to the polar cap diameter (microseconds). (c) In return current regions, where j/j(sub GJ) currents and adjust the charge density and average electric field to force-free conditions. We also

  14. Abdominal muscle activity during breathing with and without inspiratory and expiratory loads in healthy subjects.

    Science.gov (United States)

    Mesquita Montes, António; Baptista, João; Crasto, Carlos; de Melo, Cristina Argel; Santos, Rita; Vilas-Boas, João Paulo

    2016-10-01

    Central Nervous System modulates the motor activities of all trunk muscles to concurrently regulate the intra-abdominal and intra-thoracic pressures. The study aims to evaluate the effect of inspiratory and expiratory loads on abdominal muscle activity during breathing in healthy subjects. Twenty-three higher education students (21.09±1.56years; 8males) breathed at a same rhythm (inspiration: two seconds; expiration: four seconds) without load and with 10% of the maximal inspiratory or expiratory pressures, in standing. Surface electromyography was performed to assess the activation intensity of rectus abdominis, external oblique and transversus abdominis/internal oblique muscles, during inspiration and expiration. During inspiration, transversus abdominis/internal oblique activation intensity was significantly lower with inspiratory load when compared to without load (p=0.009) and expiratory load (p=0.002). During expiration, the activation intensity of all abdominal muscles was significantly higher with expiratory load when compared to without load (pactivation intensity of external oblique (p=0.036) and transversus abdominis/internal oblique (p=0.022) was significantly higher with inspiratory load when compared to without load. Transversus abdominis/internal oblique activation intensity was significantly higher with expiratory load when compared to inspiratory load (pmuscle to modulate the intra-abdominal pressure for the breathing mechanics. Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. Effect of end-expiratory lung volume on upper airway collapsibility in sleeping men and women.

    Science.gov (United States)

    Squier, Samuel B; Patil, Susheel P; Schneider, Hartmut; Kirkness, Jason P; Smith, Philip L; Schwartz, Alan R

    2010-10-01

    The relationship between changes in absolute end-expiratory lung volume (EELV) and collapsibility has not been rigorously quantified. We hypothesized that pharyngeal collapsibility varies inversely with absolute lung volume in sleeping humans during 1) conventional and 2) isovolume measurements of passive critical pressure (Pcrit). Eighteen healthy subjects (11 male, 7 female) slept in a negative pressure ventilator for measurements of pharyngeal collapsibility (Pcrit) during non-rapid eye movement sleep. EELV was 1) allowed to vary with changes in nasal pressure for conventional Pcrit measurements and 2) controlled by maintaining a fixed pressure difference across the respiratory system (P(RS)) from the nose to the body surface for isovolume Pcrit measurements at elevated EELV (P(RS) = +10 cmH(2)O), reduced EELV (P(RS) = -5 cmH(2)O), and functional residual capacity (FRC; P(RS) = 0 cmH(2)O). In each condition, the absolute EELV was determined and the corresponding Pcrit was derived from upper airway pressure-flow relationships. In the entire group, Pcrit varied inversely with EELV (P cmH(2)O/l (P cmH(2)O exhibited greater reductions in EELV and correspondingly greater decreases in the FRC isovolume compared with the conventional Pcrit (P cmH(2)O/l (P cmH(2)O, P < 0.05), implying that the men had larger lungs and more collapsible airways than the women. The ΔPcrit/ΔEELV response was independent of sex, conventional Pcrit, body mass index, and neck, waist, and hip circumferences. We conclude that Pcrit varies inversely with absolute EELV, which may lead to 1) an underestimation of the magnitude of quantitative differences in Pcrit across the spectrum from health (negative Pcrit) to disease (positive Pcrit) and 2) increases in sleep apnea susceptibility in obesity.

  16. Nasal Expiratory Positive Airway Pressure Devices (Provent for OSA: A Systematic Review and Meta-Analysis

    Directory of Open Access Journals (Sweden)

    Muhammad Riaz

    2015-01-01

    Full Text Available Objective. To quantify the effectiveness of nasal expiratory positive airway pressure (nasal EPAP devices or Provent as treatment for obstructive sleep apnea (OSA. Methods. PubMed and six other databases were searched through November 15, 2015, without language limitations. Results. Eighteen studies (920 patients were included. Pre- and post-nasal EPAP means ± standard deviations (M ± SD for apnea-hypopnea index (AHI in 345 patients decreased from 27.32±22.24 to 12.78±16.89 events/hr (relative reduction = 53.2%. Random effects modeling mean difference (MD was −14.78 events/hr [95% CI −19.12, −10.45], p value < 0.00001. Oxygen desaturation index (ODI in 247 patients decreased from 21.2±19.3 to 12.4±14.1 events/hr (relative reduction = 41.5%, p value < 0.00001. Lowest oxygen saturation (LSAT M ± SD improved in 146 patients from 83.2±6.8% to 86.2±11.1%, MD 3 oxygen saturation points [95% CI 0.57, 5.63]. Epworth Sleepiness Scale (ESS M ± SD improved (359 patients from 9.9±5.3 to 7.4±5.0, MD −2.5 [95% CI −3.2, −1.8], p value < 0.0001. Conclusion. Nasal EPAP (Provent reduced AHI by 53.2%, ODI by 41.5% and improved LSAT by 3 oxygen saturation points. Generally, there were no clear characteristics (demographic factors, medical history, and/or physical exam finding that predicted favorable response to these devices. However, limited evidence suggests that high nasal resistance could be associated with treatment failure. Additional studies are needed to identify demographic and polysomnographic characteristics that would predict therapeutic success with nasal EPAP (Provent.

  17. Determination of fatty acid oxidation in premature infants by means of 13CO2 expiratory tests with simultaneous, continuous infusion of 13C-triolein

    International Nuclear Information System (INIS)

    Broesicke, H.

    1987-01-01

    It was the purpose of this long-term test to develop a method of determining the parameters of metabolism in isotopic flow equilibrium adapted to the specific conditions of intravenous feeding. The most important requirement to be met for this 13 CO 2 expiratory test is constant supply of the substrate, and this condition is fulfilled by the parenteral alimentation of premature infants or newborn babies, so that the study was carried out on this group of patients. (orig./MG) With 37 figs., 14 tabs [de

  18. Flow

    DEFF Research Database (Denmark)

    Knoop, Hans Henrik

    2006-01-01

    FLOW. Orden i hovedet på den fede måde Oplevelsesmæssigt er flow-tilstanden kendetegnet ved at man er fuldstændig involveret, fokuseret og koncentreret; at man oplever stor indre klarhed ved at vide hvad der skal gøres, og i hvilket omfang det lykkes; at man ved at det er muligt at løse opgaven...

  19. Does attenuated skin blood flow lower sweat rate and the critical environmental limit for heat balance during severe heat exposure?

    Science.gov (United States)

    Cramer, Matthew N; Gagnon, Daniel; Crandall, Craig G; Jay, Ollie

    2017-02-01

    What is the central question of this study? Does attenuated skin blood flow diminish sweating and reduce the critical environmental limit for heat balance, which indicates maximal heat loss potential, during severe heat stress? What is the main finding and its importance? Isosmotic hypovolaemia attenuated skin blood flow by ∼20% but did not result in different sweating rates, mean skin temperatures or critical environmental limits for heat balance compared with control and volume-infusion treatments, suggesting that the lower levels of skin blood flow commonly observed in aged and diseased populations may not diminish maximal whole-body heat dissipation. Attenuated skin blood flow (SkBF) is often assumed to impair core temperature (T c ) regulation. Profound pharmacologically induced reductions in SkBF (∼85%) lead to impaired sweating, but whether the smaller attenuations in SkBF (∼20%) more often associated with ageing and certain diseases lead to decrements in sweating and maximal heat loss potential is unknown. Seven healthy men (28 ± 4 years old) completed a 30 min equilibration period at 41°C and a vapour pressure (P a ) of 2.57 kPa followed by incremental steps in P a of 0.17 kPa every 6 min to 5.95 kPa. Differences in heat loss potential were assessed by identifying the critical vapour pressure (P crit ) at which an upward inflection in T c occurred. The following three separate treatments elicited changes in plasma volume to achieve three distinct levels of SkBF: control (CON); diuretic-induced isosmotic dehydration to lower SkBF (DEH); and continuous saline infusion to maintain SkBF (SAL). The T c , mean skin temperature (T sk ), heart rate, mean laser-Doppler flux (forearm and thigh; LDF mean ), mean local sweat rate (forearm and thigh; LSR mean ) and metabolic rate were measured. In DEH, a 14.2 ± 5.7% lower plasma volume resulted in a ∼20% lower LDF mean in perfusion units (PU) (DEH, 139 ± 23 PU; CON, 176 ± 22 PU; and SAL

  20. Positive expiratory pressure improves oxygenation in healthy subjects exposed to hypoxia.

    Directory of Open Access Journals (Sweden)

    Hugo Nespoulet

    Full Text Available INTRODUCTION: Positive end-expiratory pressure (PEEP is commonly used in critical care medicine to improve gas exchange. Altitude sickness is associated with exaggerated reduction in arterial oxygenation. We assessed the effect of PEEP and pursed lips breathing (PLB on arterial and tissue oxygenation under normobaric and hypobaric hypoxic conditions. METHODS: Sixteen healthy volunteers were exposed to acute normobaric hypoxia (Laboratory study, FiO₂=0.12. The protocol consisted in 3-min phases with PEEPs of 0, 5 or 10 cmH₂O, PLB or similar ventilation than with PEEP-10, interspaced with 3-min phases of free breathing. Arterial (pulse oximetry and quadriceps (near-infrared spectroscopy oxygenation, ventilation, cardiac function, esophageal and gastric pressures and subjects' subjective perceptions were recorded continuously. In addition, the effect of PEEP on arterial oxygenation was tested at 4,350 m of altitude in 9 volunteers breathing for 20 min with PEEP-10 (Field study. RESULTS: During the laboratory study, PEEP-10 increased arterial and quadriceps oxygenation (arterial oxygen saturation +5.6±5.0% and quadriceps oxyhemoglobin +58±73 µmol.cm compared to free breathing; p0.05 compared to PEEP-0. During the field study, PEEP-10 increased arterial oxygen saturation by +6.7±6.0% after the 3(rd minute with PEEP-10 without further significant increase until the 20(th minute with PEEP-10. Subjects did not report any significant discomfort with PEEP. CONCLUSIONS: These data indicate that 10-cmH₂O PEEP significantly improves arterial and muscle oxygenation under both normobaric and hypobaric hypoxic conditions in healthy subjects. PEEP-10 could be an attractive non-pharmacological tool to limit blood oxygen desaturation and possibly symptoms at altitude.

  1. Positive expiratory pressure improves oxygenation in healthy subjects exposed to hypoxia.

    Science.gov (United States)

    Nespoulet, Hugo; Rupp, Thomas; Bachasson, Damien; Tamisier, Renaud; Wuyam, Bernard; Lévy, Patrick; Verges, Samuel

    2013-01-01

    Positive end-expiratory pressure (PEEP) is commonly used in critical care medicine to improve gas exchange. Altitude sickness is associated with exaggerated reduction in arterial oxygenation. We assessed the effect of PEEP and pursed lips breathing (PLB) on arterial and tissue oxygenation under normobaric and hypobaric hypoxic conditions. Sixteen healthy volunteers were exposed to acute normobaric hypoxia (Laboratory study, FiO₂=0.12). The protocol consisted in 3-min phases with PEEPs of 0, 5 or 10 cmH₂O, PLB or similar ventilation than with PEEP-10, interspaced with 3-min phases of free breathing. Arterial (pulse oximetry) and quadriceps (near-infrared spectroscopy) oxygenation, ventilation, cardiac function, esophageal and gastric pressures and subjects' subjective perceptions were recorded continuously. In addition, the effect of PEEP on arterial oxygenation was tested at 4,350 m of altitude in 9 volunteers breathing for 20 min with PEEP-10 (Field study). During the laboratory study, PEEP-10 increased arterial and quadriceps oxygenation (arterial oxygen saturation +5.6±5.0% and quadriceps oxyhemoglobin +58±73 µmol.cm compared to free breathing; pbreathing pattern, end-tidal CO₂ or cardiac function (all p>0.05) compared to PEEP-0. During the field study, PEEP-10 increased arterial oxygen saturation by +6.7±6.0% after the 3(rd) minute with PEEP-10 without further significant increase until the 20(th) minute with PEEP-10. Subjects did not report any significant discomfort with PEEP. These data indicate that 10-cmH₂O PEEP significantly improves arterial and muscle oxygenation under both normobaric and hypobaric hypoxic conditions in healthy subjects. PEEP-10 could be an attractive non-pharmacological tool to limit blood oxygen desaturation and possibly symptoms at altitude.

  2. Peak Expiratory Flow as a Surrogate for Health Related Quality of ...

    African Journals Online (AJOL)

    Spirometry was done using American Thoracic Society's standards and reference equations from African American norms of the US population. Quality of life was measured with the St George's Respiratory Questionnaire (SGRQ) Results: Out of 50 patients recruited for the study, 48 provided complete data with acceptable ...

  3. Daily changes of peak expiratory flow and respiratory symptom occurrence around a soy processing factory

    NARCIS (Netherlands)

    Heederik, Dick; Doekes, Gert; van Strien, Rob; Brunekreef, Bert

    2014-01-01

    Objectives. To evaluate sensitization and acute respiratory health effects in inhabitants living in the vicinity of a factory producing soy oil. Methods. Two panels of potential responders were created on the basis of a response to a short screening questionnaire sent to random samples of 1,000

  4. Evaluation of Peak Expiratory Flow Rates (PEFR) of Workers in a ...

    African Journals Online (AJOL)

    DATONYE ALASIA

    ABSTRACT: Background: Occupational lung diseases. (OLD) remain one of the most common workplace health challenges since the industrial revolution. One of the risks for OLD is the exposure to cement dust which is associated with varying degrees of respiratory symptoms and reduction in lung function. This study ...

  5. Evaluation of Peak Expiratory Flow rates (PEFR) of Workers in a ...

    African Journals Online (AJOL)

    Background: Occupational lung diseases (OLD) remain one of the most common workplace health challenges since the industrial revolution. One of the risks for OLD is the exposure to cement dust which is associated with varying degrees of respiratory symptoms and reduction in lung function. This study aimed to measure ...

  6. Carbon dioxide rebreathing caused by deformed silicon leaflet in the expiratory unidirectional valve

    Directory of Open Access Journals (Sweden)

    Arumugam Vasudevan

    2013-01-01

    Full Text Available Rebreathing of carbon dioxide caused by incompetent ′cage and disc′ unidirectional valves has been reported earlier. Some manufacturers have changed the design of unidirectional valves to ′flexible leaflets′. We report a series of cases where a deformed membrane leaflet in expiratory unidirectional valves led to rebreathing of carbon dioxide.

  7. Dead space and slope indices from the expiratory carbon dioxide tension-volume curve

    NARCIS (Netherlands)

    A.H. Kars (Alice); J.M. Bogaard (Jan); Th. Stijnen (Theo); J. de Vries; A.F.M. Verbraak (Anton); C. Hilvering

    1997-01-01

    textabstractThe slope of phase 3 and three noninvasively determined dead space estimates derived from the expiratory carbon dioxide tension (PCO2) versus volume curve, including the Bohr dead space (VD,Bohr), the Fowler dead space (VD,Fowler) and pre-interface expirate

  8. EFFECTS OF POSITIVE EXPIRATORY PRESSURE BREATHING DURING EXERCISE IN PATIENTS WITH COPD

    NARCIS (Netherlands)

    VANDERSCHANS, GP; DEJONG, W; DEVRIES, G; KAAN, WA; POSTMA, DS; KOETER, GH; VANDERMARK, TW

    The effect of breathing with a positive expiratory pressure of 5 cm H2O was investigated in eight patients with COPD (mean [SD] FEV(1) = 54 [13] percent predicted). Specific work of breathing (Wsp) and myoelectrical activity of the following respiratory muscles were measured at rest: scalene muscle,

  9. EFFECT OF POSITIVE EXPIRATORY PRESSURE BREATHING IN PATIENTS WITH CYSTIC-FIBROSIS

    NARCIS (Netherlands)

    VANDERSCHANS, CP; VANDERMARK, TW; DEVRIES, G; PIERS, DA; BEEKHUIS, H; DANKERTROELSE, JE; POSTMA, DS; KOETER, GH

    The effect of positive expiratory pressure breathing, alone and in combination with coughing, was investigated in eight patients with cystic fibrosis. Functional residual capacity and total lung capacity was measured with a body plethysmograph before, during, and immediately after breathing with

  10. Pharmacologic Interventions to Improve Splanchnic Oxygenation During Ventilation with Positive End-Expiratory Pressure

    NARCIS (Netherlands)

    Fournell, A.; Scheeren, T. W. L.; Picker, O.; Schwarte, L. A.; Wolf, M; Bucher, HU; Rudin, M; VanHuffel, S; Wolf, U; Bruley, DF; Harrison, DK

    2012-01-01

    Mechanical ventilation with positive end-expiratory pressure (PEEP) is an indispensable tool in the management of respiratory failure to preserve or improve lung function and systemic oxygenation. However, PEEP per se may also, as has been shown in experimental animals, impair regional

  11. THE EFFECT OF SUBMAXIMAL INHALATION ON MEASURES DERIVED FROM FORCED EXPIRATORY SPIROMETRY

    Science.gov (United States)

    THE EFFECT OF SUBMAXIMAL INHALATION ON MEASURES DERIVED FROM FORCED EXPIRATORY SPIROMETRY. William F. McDonnell Human Studies Division, NHEERL, U.S. Environmental Protection Agency, RTP, NC 27711. Short-term exposure to ozone results in a neurally-mediated decrease in the ab...

  12. Modeling the Fate of Expiratory Aerosols and the Associated Infection Risk in an Aircraft Cabin Environment

    DEFF Research Database (Denmark)

    Wan, M.P.; To, G.N.S.; Chao, C.Y.H.

    2009-01-01

    The transport and deposition of polydispersed expiratory aerosols in an aircraft cabin were simulated using a Lagrangian-based model validated by experiments conducted in an aircraft cabin mockup. Infection risk by inhalation was estimated using the aerosol dispersion data and a model was developed...

  13. Effects of midline laparotomy on expiratory muscle activation in anesthetized dogs.

    Science.gov (United States)

    Farkas, G A; De Troyer, A

    1989-08-01

    Abdominal surgery has a marked inhibitory influence on the diaphragm, but its effect on the expiratory muscles is not known. Therefore, we have recorded the electromyograms of the triangularis sterni, abdominal external oblique, and transversus abdominis before and after a midline laparotomy in 10 anesthetized, spontaneously breathing dogs. Measurements were obtained during quiet breathing in the supine posture, during breathing against expiratory threshold loads, during head-up tilting, and during hyperoxic hypercapnia. Expiratory activation of the transversus abdominis in all conditions was considerably reduced after laparotomy. This reduction was real, as no change in the compound muscle action potential during single pulse stimulation was observed. In contrast, expiratory recruitment of either the triangularis sterni or the abdominal external oblique was maintained or increased. We therefore conclude that laparotomy inhibits not only activation of the diaphragm during inspiration but also activation of the transversus abdominis during expiration. Visceral afferents thus affect in concert the two respiratory muscles lining the peritoneum. The present findings also emphasize the important fact that the pattern of activation of a particular abdominal muscle is not necessarily representative of the entire abdominal musculature.

  14. Changes in forced expiratory volume in 1 second over time in COPD

    DEFF Research Database (Denmark)

    Vestbo, Jørgen; Edwards, Lisa D; Scanlon, Paul D

    2011-01-01

    A key feature of chronic obstructive pulmonary disease (COPD) is an accelerated rate of decline in forced expiratory volume in 1 second (FEV(1)), but data on the variability and determinants of this change in patients who have established disease are scarce....

  15. Influence of inspiratory resistive loading on expiratory muscle fatigue in healthy humans.

    Science.gov (United States)

    Peters, Carli M; Welch, Joseph F; Dominelli, Paolo B; Molgat-Seon, Yannick; Romer, Lee M; McKenzie, Donald C; Sheel, A William

    2017-09-01

    What is the central question of this study? This study is the first to measure objectively both inspiratory and expiratory muscle fatigue after inspiratory resistive loading to determine whether the expiratory muscles are activated to the point of fatigue when specifically loading the inspiratory muscles. What is the main finding and its importance? The absence of abdominal muscle fatigue suggests that future studies attempting to understand the neural and circulatory consequences of diaphragm fatigue can use inspiratory resistive loading without considering the confounding effects of abdominal muscle fatigue. Expiratory resistive loading elicits inspiratory as well as expiratory muscle fatigue, suggesting parallel coactivation of the inspiratory muscles during expiration. It is unknown whether the expiratory muscles are likewise coactivated to the point of fatigue during inspiratory resistive loading (IRL). The purpose of this study was to determine whether IRL elicits expiratory as well as inspiratory muscle fatigue. Healthy male subjects (n = 9) underwent isocapnic IRL (60% maximal inspiratory pressure, 15 breaths min -1 , 0.7 inspiratory duty cycle) to task failure. Abdominal and diaphragm contractile function was assessed at baseline and at 3, 15 and 30 min post-IRL by measuring gastric twitch pressure (P ga,tw ) and transdiaphragmatic twitch pressure (P di,tw ) in response to potentiated magnetic stimulation of the thoracic and phrenic nerves, respectively. Fatigue was defined as a significant reduction from baseline in P ga,tw or P di,tw . Throughout IRL, there was a time-dependent increase in cardiac frequency and mean arterial blood pressure, suggesting activation of the respiratory muscle metaboreflex. The P di,tw was significantly lower than baseline (34.3 ± 9.6 cmH 2 O) at 3 (23.2 ± 5.7 cmH 2 O, P muscle fatigue. Agonist-antagonist interactions for the respiratory muscles appear to be more important during expiratory versus inspiratory

  16. Detection of nanoplastics in food by asymmetric flow field-flow fractionation coupled to multi-angle light scattering: possibilities, challenges and analytical limitations

    DEFF Research Database (Denmark)

    Correia, Manuel; Löschner, Katrin

    2018-01-01

    We tested the suitability of asymmetric flow field-flow fractionation (AF4) coupled to multi-angle light scattering (MALS) for detection of nanoplastics in fish. A homogenized fish sample was spiked with 100 nm polystyrene nanoparticles (PSNPs) (1.3 mg/g fish). Two sample preparation strategies w...

  17. Expiratory rib cage compression in mechanically ventilated adults: systematic review with meta-analysis

    Science.gov (United States)

    Borges, Lúcia Faria; Saraiva, Mateus Sasso; Saraiva, Marcos Ariel Sasso; Macagnan, Fabrício Edler; Kessler, Adriana

    2017-01-01

    Objective To review the literature on the effects of expiratory rib cage compression on ventilatory mechanics, airway clearance, and oxygen and hemodynamic indices in mechanically ventilated adults. Methods Systematic review with meta-analysis of randomized clinical trials in the databases MEDLINE (via PubMed), EMBASE, Cochrane CENTRAL, PEDro, and LILACS. Studies on adult patients hospitalized in intensive care units and under mechanical ventilation that analyzed the effects of expiratory rib cage compression with respect to a control group (without expiratory rib cage compression) and evaluated the outcomes static and dynamic compliance, sputum volume, systolic blood pressure, diastolic blood pressure, mean arterial pressure, heart rate, peripheral oxygen saturation, and ratio of arterial oxygen partial pressure to fraction of inspired oxygen were included. Experimental studies with animals and those with incomplete data were excluded. Results The search strategy produced 5,816 studies, of which only three randomized crossover trials were included, totaling 93 patients. With respect to the outcome of heart rate, values were reduced in the expiratory rib cage compression group compared with the control group [-2.81 bpm (95% confidence interval [95%CI]: -4.73 to 0.89; I2: 0%)]. Regarding dynamic compliance, there was no significant difference between groups [-0.58mL/cmH2O (95%CI: -2.98 to 1.82; I2: 1%)]. Regarding the variables systolic blood pressure and diastolic blood pressure, significant differences were found after descriptive evaluation. However, there was no difference between groups regarding the variables secretion volume, static compliance, ratio of arterial oxygen partial pressure to fraction of inspired oxygen, and peripheral oxygen saturation. Conclusion There is a lack of evidence to support the use of expiratory rib cage compression in routine care, given that the literature on this topic offers low methodological quality and is inconclusive. PMID

  18. Rebreathing in the Mapleson A, C and D breathing systems with sinusoidal and exponential flow waveforms.

    Science.gov (United States)

    Cook, L B

    1997-12-01

    The degree of rebreathing in Mapleson A, C and D breathing systems for sinusoidal and exponential flow waveforms is analysed mathematically. The effects of altering the I:E ratio and of introducing an expiratory pause are investigated. The results for sinusoidal waveforms closely resemble those for a square wave. Exponential flow waveforms produce results similar to triangular flow waveforms. The Mapleson A system is always the most efficient. The Mapleson C system is efficient when the I:E ratio is 1:1, becoming less efficient with longer expiration and very inefficient with an expiratory pause. The Mapleson D system becomes efficient when the expiratory pause is long.

  19. The closed circuit and the low flow systems

    Directory of Open Access Journals (Sweden)

    S Parthasarathy

    2013-01-01

    Full Text Available A breathing system is defined as an assembly of components, which delivers gases from the anesthesia machine to the patients′ airways. When the components are arranged as a circle, it is termed a circle system. The flow of exhaled gases is unidirectional in the system. The system contains a component (absorber, which absorbs exhaled carbon dioxide and it is not necessary to give high fresh gas flows as in Mapleson systems. When the adjustable pressure limiting (APL valve is closed and all the exhaled gases without carbon dioxide are returned to the patient, the system becomes a totally closed one. Such a circle system can be used with flows as low as 250 to 500 mL and clinically can be termed as low-flow systems. The components of the circle system can be arranged in different ways with adherence to basic rules: (1 Unidirectional valve must be present between the reservoir bag and the patient on both inspiratory and expiratory sides; (2 fresh gas must not enter the system between the expiratory unidirectional valve and the patient; and (3 the APL valve must not be placed between the patient and the inspiratory unidirectional valve. The functional analysis is explained in detail. During the function, the arrangement of components is significant only at higher fresh gas flows. With the introduction of low resistance valves, improved soda lime canisters and low dead space connectors, the use of less complicated pediatric circle systems is gaining popularity to anesthetize children. There are bidirectional flow systems with carbon dioxide absorption. The Waters to and fro system, a classic example of bidirectional flow systems with a canister to absorb carbon dioxide, is valveless and portable. It was widely used in the past and now is only of historical importance.

  20. [Clinical research of using optimal compliance to determine positive end-expiratory pressure].

    Science.gov (United States)

    Xu, Lei; Feng, Quan-sheng; Lian, Fu; Shao, Xin-hua; Li, Zhi-bo; Wang, Zhi-yong; Li, Jun

    2012-07-01

    To observe the availability and security of optimal compliance strategy to titrate the optimal positive end-expiratory pressure (PEEP), compared with quasi-static pressure-volume curve (P-V curve) traced by low-flow method. Fourteen patients received mechanical ventilation with acute respiratory distress syndrome (ARDS) admitted in intensive care unit (ICU) of Tianjin Third Central Hospital from November 2009 to December 2010 were divided into two groups(n = 7). The quasi-static P-V curve method and the optimal compliance titration were used to set the optimal PEEP respectively, repeated 3 times in a row. The optimal PEEP and the consistency of repeated experiments were compared between groups. The hemodynamic parameters, oxygenation index (OI), lung compliance (C), cytokines and pulmonary surfactant-associated protein D (SP-D) concentration in plasma before and 2, 4, and 6 hours after the experiment were observed in each group. (1) There were no significant differences in gender, age and severity of disease between two groups. (2)The optimal PEEP [cm H(2)O, 1 cm H(2)O=0.098 kPa] had no significant difference between quasi-static P-V curve method group and the optimal compliance titration group (11.53 ± 2.07 vs. 10.57 ± 0.87, P>0.05). The consistency of repeated experiments in quasi-static P-V curve method group was poor, the slope of the quasi-static P-V curve in repeated experiments showed downward tendency. The optimal PEEP was increasing in each measure. There was significant difference between the first and the third time (10.00 ± 1.58 vs. 12.80 ± 1.92, P vs. 93.71 ± 5.38, temperature: 38.05 ± 0.73 vs. 36.99 ± 1.02, IL-6: 144.84 ± 23.89 vs. 94.73 ± 5.91, TNF-α: 151.46 ± 46.00 vs. 89.86 ± 13.13, SP-D: 33.65 ± 8.66 vs. 16.63 ± 5.61, MAP: 85.47 ± 9.24 vs. 102.43 ± 8.38, CCI: 3.00 ± 0.48 vs. 3.81 ± 0.81, OI: 62.00 ± 21.45 vs. 103.40 ± 37.27, C: 32.10 ± 2.92 vs. 49.57 ± 7.18, all P safety and usability.

  1. High-inflation pressure and positive end-expiratory pressure. Injurious to the lung? No.

    Science.gov (United States)

    Nelson, L D

    1996-07-01

    during ARDS) and limiting exposure to toxic concentrations of oxygen minimize ventilator-induced secondary lung injury and maximize chances for survival. Arbitrary limitations of peak inspiratory or end-expiratory airway pressure or mandatory tidal volume in patients with severe ARDS seem to be unfounded. Failure to achieve adequate physiologic end-points in these patients may increase morbidity and mortality rates.

  2. The Neopuff's PEEP valve is flow sensitive.

    LENUS (Irish Health Repository)

    Hawkes, Colin Patrick

    2011-03-01

    The current recommendation in setting up the Neopuff is to use a gas flow of 5-15 L\\/min. We investigated if the sensitivity of the positive end expiratory pressure (PEEP) valve varies at different flow rates within this range.

  3. Interaction between intra-abdominal pressure and positive-end expiratory pressure

    Directory of Open Access Journals (Sweden)

    Jamili Anbar Torquato

    2009-02-01

    Full Text Available OBJECTIVE: The aim of this study was to quantify the interaction between increased intra-abdominal pressure and Positive-End Expiratory Pressure. METHODS: In 30 mechanically ventilated ICU patients with a fixed tidal volume, respiratory system plateau and abdominal pressure were measured at a Positive-End Expiratory Pressure level of zero and 10 cm H2O. The measurements were repeated after placing a 5 kg weight on the patients' belly. RESULTS: After the addition of 5 kg to the patients' belly at zero Positive-End Expiratory Pressure, both intra-abdominal pressure (p<0.001 and plateau pressures (p=0.005 increased significantly. Increasing the Positive-End Expiratory Pressure levels from zero to 10 cm H2O without weight on the belly did not result in any increase in intra-abdominal pressure (p=0.165. However, plateau pressures increased significantly (p< 0.001. Increasing Positive-End Expiratory Pressure from zero to 10 cm H2O and adding 5 kg to the belly increased intra-abdominal pressure from 8.7 to 16.8 (p<0.001 and plateau pressure from 18.26 to 27.2 (p<0.001. Maintaining Positive-End Expiratory Pressure at 10 cm H2O and placing 5 kg on the belly increased intra-abdominal pressure from 12.3 +/- 1.7 to 16.8 +/- 1.7 (p<0.001 but did not increase plateau pressure (26.6+/-1.2 to 27.2 +/-1.1 -p=0.83. CONCLUSIONS: The addition of a 5kg weight onto the abdomen significantly increased both IAP and the airway plateau pressure, confirming that intra-abdominal hypertension elevates the plateau pressure. However, plateau pressure alone cannot be considered a good indicator for the detection of elevated intra-abdominal pressure in patients under mechanical ventilation using PEEP. In these patients, the intra-abdominal pressure must also be measured.

  4. Segmentation of expiratory and inspiratory sounds in baby cry audio recordings using hidden Markov models.

    Science.gov (United States)

    Aucouturier, Jean-Julien; Nonaka, Yulri; Katahira, Kentaro; Okanoya, Kazuo

    2011-11-01

    The paper describes an application of machine learning techniques to identify expiratory and inspiration phases from the audio recording of human baby cries. Crying episodes were recorded from 14 infants, spanning four vocalization contexts in their first 12 months of age; recordings from three individuals were annotated manually to identify expiratory and inspiratory sounds and used as training examples to segment automatically the recordings of the other 11 individuals. The proposed algorithm uses a hidden Markov model architecture, in which state likelihoods are estimated either with Gaussian mixture models or by converting the classification decisions of a support vector machine. The algorithm yields up to 95% classification precision (86% average), and its ability generalizes over different babies, different ages, and vocalization contexts. The technique offers an opportunity to quantify expiration duration, count the crying rate, and other time-related characteristics of baby crying for screening, diagnosis, and research purposes over large populations of infants.

  5. Detection of T and B cells specific complement-fixing alloantibodies using flow cytometry: A diagnostic approach for a resource limited laboratory

    Directory of Open Access Journals (Sweden)

    Dharmendra Jain

    2017-01-01

    Conclusions: We postulate that this method incorporates most of the features of all the available modalities (i.e., National Institute of Health-complement dependent lymphocytotoxicity, FCXM, cytotoxic FCXM and C4d-flowPRA yet cost-effective and best suited for resource-limited laboratory/ies which is a common scenario in developing countries.

  6. The effect of statin treatment on the prevention of stent mediated flow limited edge dissections during PCI in patients with stable angina.

    Science.gov (United States)

    Oksuz, Fatih; Yarlioglues, Mikail; Yayla, Cagrı; Canpolat, Ugur; Murat, Sani Namık; Aydogdu, Sinan

    2016-10-01

    The effect of statin therapy before PCI with direct stenting may reduce the development of flow limited edge dissections (ED) in patients with stable angina. Flow limited ED after PCI is associated with an increased risk of major adverse cardiovascular events. Statin therapy induces important changes in the plaque composition which have been previously identified as strong predictors of ED. 100 patients complicated with flow limited ED and 100 control patients with successful procedure were enrolled into the study. EDs were described as the 5-mm regions that were immediately adjacent to the stent borders, both distally and proximally on the coronary angiography. Rate of statin use and duration of statin use were significantly higher in patients with non-ED group (63%) versus ED group (25%) (p<0.001). In addition, patients in ED group had significantly higher levels of C-reactive protein (CRP) at admission (9.9mg/dL (5.89-16.45) vs. 4.40mg/dL (3.5-7.09), respectively, p=0.014). Our findings suggested that maintenance statin treatment before PCI with direct stenting may reduce the development of flow limited ED in patients with stable angina. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  7. Focal airtrapping at expiratory high-resolution CT: comparison with pulmonary function tests

    International Nuclear Information System (INIS)

    Kauczor, H.U.; Hast, J.; Heussel, C.P.; Mildenberger, P.; Thelen, M.; Schlegel, J.

    2000-01-01

    This study was undertaken to determine prevalence, extent, and severity of focal airtrapping at expiratory high-resolution CT, and to compare focal airtrapping with age, gender, pulmonary function tests, and blood gas analysis. Two-hundred seventeen patients with and without pulmonary disease underwent paired inspiratory/expiratory high-resolution CT. Six scan pairs with corresponding scan levels were visually assessed for focal - not diffuse - airtrapping using a four-point scale. Pulmonary function tests and blood gas analysis were available for correlation in all patients (mean interval 5 days). Focal airtrapping with lower lung predominance was observed in 80 % of patients. Twenty-six of 26 patients with restrictive lung function impairment exhibited focal airtrapping (mean score 2.4), whereas only 72 of 98 (74 %) patients with obstruction did (mean score 1.5; p < 0.05). Fifty-eight of 70 (83 %) patients with normal lung function (mean score 1.8) and 19 of 23 (83 %) patients with mixed impairment (mean score 1.8) had focal airtrapping. Focal airtrapping showed negative correlations with static lung volumes (-0.27 to -0.37; p < 0.001) in all patients and moderate positive correlations with dynamic parameters (0.3-0.4; p < 0.001) in patients with obstruction. No significant correlations were found with age, gender, and blood gas analysis. Visual assessment of focal - not diffuse - airtrapping at expiratory high-resolution CT does not correlate with physiological evidence of obstruction as derived from pulmonary function tests since the perception of focal airtrapping requires an adequate expiratory increase in lung density. (orig.)

  8. High resolution CT in cystic fibrosis--the contribution of expiratory scans

    International Nuclear Information System (INIS)

    Dorloechter, Ludger; Nes, Harald; Fluge, Gjermund; Rosendahl, Karen

    2003-01-01

    Introduction: The use of high-resolution computed tomography (HRCT) is well accepted as an accurate method for evaluation of lung parenchyma in cystic fibrosis (CF). Several scoring methods exist and, in common, all are based on HRCT findings during inspiration alone. Objective: To examine whether expiratory HRCT scans could add information about the degree of mosaic perfusion in patients with CF. Methods and patients: Pulmonary HRCT was performed in 17 CF patients (median age of 12 years) with 1-mm thin sections and 10-mm intervals during inspiration, followed by 1-mm thin sections with 20-mm intervals during expiration. HRCT was scored by using a modified Bhalla method. Results: The mean HRCT score was 8.2. Out of 17 patients, 11 (65%) demonstrated a pathological mosaic perfusion in expiration, while only three patients showed mosaic perfusion in inspiration. The degree of expiratory mosaic perfusion was graded as severe in nine patients and moderate in two patients. There was a significant correlation between our modified HRCT score and lung function, as measured by forced expiratory volume in 1 s (FEV1% predicted, P<0.01). Conclusion: Mosaic perfusion in expiration was a common pathological HRCT finding in our study group. The clinical significance of this finding needs further evaluation

  9. Chemical Safety Alert: Emergency Isolation for Hazardous Material Fluid Transfer Systems - Application and Limitations of Excess Flow Valves

    Science.gov (United States)

    While excess flow valves (EFV) are in extensive service and have prevented numerous pipe or hose breaks from becoming much more serious incidents, experience shows that in some cases the EFV did not perform as intended, usually because of misapplication.

  10. The differential effects of inspiratory, expiratory, and combined resistive breathing on healthy lung

    Directory of Open Access Journals (Sweden)

    Loverdos K

    2016-07-01

    Full Text Available Konstantinos Loverdos,1 Dimitrios Toumpanakis,1 Eleni Litsiou,1 Vassiliki Karavana,1 Constantinos Glynos,1 Christina Magkou,2 Stamatios Theocharis,3 Theodoros Vassilakopoulos1 1Department of Critical Care, Pulmonary Unit and Marianthi Simou Applied Biomedical Research and Training Center, Evangelismos General Hospital, University of Athens Medical School, 2Department of Pathology, Evangelismos General Hospital, 31st Department of Pathology, University of Athens Medical School, Athens, Greece Abstract: Combined resistive breathing (CRB is the hallmark of obstructive airway disease pathophysiology. We have previously shown that severe inspiratory resistive breathing (IRB induces acute lung injury in healthy rats. The role of expiratory resistance is unknown. The possibility of a load-dependent type of resistive breathing-induced lung injury also remains elusive. Our aim was to investigate the differential effects of IRB, expiratory resistive breathing (ERB, and CRB on healthy rat lung and establish the lowest loads required to induce injury. Anesthetized tracheostomized rats breathed through a two-way valve. Varying resistances were connected to the inspiratory, expiratory, or both ports, so that the peak inspiratory pressure (IRB was 20%–40% or peak expiratory (ERB was 40%–70% of maximum. CRB was assessed in inspiratory/expiratory pressures of 30%/50%, 40%/50%, and 40%/60% of maximum. Quietly breathing animals served as controls. At 6 hours, respiratory system mechanics were measured, and bronchoalveolar lavage was performed for measurement of cell and protein concentration. Lung tissue interleukin-6 and interleukin-1β levels were estimated, and a lung injury histological score was determined. ERB produced significant, load-independent neutrophilia, without mechanical or permeability derangements. IRB 30% was the lowest inspiratory load that provoked lung injury. CRB increased tissue elasticity, bronchoalveolar lavage total cell, macrophage

  11. An Enhanced Discrete Artificial Bee Colony Algorithm to Minimize the Total Flow Time in Permutation Flow Shop Scheduling with Limited Buffers

    Directory of Open Access Journals (Sweden)

    Guanlong Deng

    2016-01-01

    Full Text Available This paper presents an enhanced discrete artificial bee colony algorithm for minimizing the total flow time in the flow shop scheduling problem with buffer capacity. First, the solution in the algorithm is represented as discrete job permutation to directly convert to active schedule. Then, we present a simple and effective scheme called best insertion for the employed bee and onlooker bee and introduce a combined local search exploring both insertion and swap neighborhood. To validate the performance of the presented algorithm, a computational campaign is carried out on the Taillard benchmark instances, and computations and comparisons show that the proposed algorithm is not only capable of solving the benchmark set better than the existing discrete differential evolution algorithm and iterated greedy algorithm, but also capable of performing better than two recently proposed discrete artificial bee colony algorithms.

  12. The effect of direct and counter-current flow-through delignification on enzymatic hydrolysis of wheat straw, and flow limits due to compressibility.

    Science.gov (United States)

    Pihlajaniemi, Ville; Sipponen, Mika Henrikki; Pastinen, Ossi; Nyyssölä, Antti; Laakso, Simo

    2016-12-01

    This article compares the processes for wheat straw lignocellulose fractionation by percolation, counter-current progressing batch percolation and batch reaction at low NaOH-loadings (3-6% of DM). The flow-through processes were found to improve delignification and subsequent enzymatic saccharification, reduce NaOH-consumption and allow reduction of thermal severity, whereas hemicellulose dissolution was unaffected. However, contrary to previous expectations, a counter-current process did not provide additional benefits to regular percolation. The compressibility and flow properties of a straw bed were determined and used for simulation of the packing density profile and dynamic pressure in an industrial scale column. After dissolution of 30% of the straw DM by delignification, a pressure drop above 100 kPa m -1 led to clogging of the flow due to compaction of straw. Accordingly, the maximum applicable feed pressure and volumetric straw throughput was determined as a function of column height, indicating that a 10 m column can be operated at a maximum feed pressure of 530 kPa, corresponding to an operation time of 50 min and a throughput of 163 kg m -3  h -1 . Biotechnol. Bioeng. 2016;113: 2605-2613. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  13. The importance of the expiratory pause. Comparison of the Mapleson A, C and D breathing systems using a lung model.

    Science.gov (United States)

    Cook, L B

    1996-05-01

    A physical lung model simulating spontaneous respiration was used to investigate the influence of the respiratory pattern on the efficiency of the Mapleson A, C and D breathing systems. It is shown that the Mapleson A system is always the most efficient breathing system and that its performance is relatively independent of the respiratory pattern. When the expiratory pause is minimal, the Mapleson C system is almost as efficient as the Mapleson A, but becomes ever less efficient as the expiratory pause increases. The Mapleson D system is very inefficient when the expiratory pause is short. With a longer expiratory pause, this system's efficiency approaches that of the Mapleson A. The experimental results are compared with predictions generated by a mathematical model. There is good agreement between the two, validating the mathematics used.

  14. Experimental Study of Dispersion and Deposition of Expiratory Aerosols in Aircraft Cabins and Impact on Infectious Disease Transmission

    DEFF Research Database (Denmark)

    To, G.N.S.; Wan, M.P.; Chao, C.Y.H.

    2009-01-01

    The dispersion and deposition characteristics of polydispersed expiratory aerosols were investigated in an aircraft cabin mockup to study the transmission of infectious diseases. The airflow was characterized by particle image velocimetry (PIV) measurements. Aerosol dispersionwas measured...

  15. A Comprehensive Prediction Model of Hydraulic Extended-Reach Limit Considering the Allowable Range of Drilling Fluid Flow Rate in Horizontal Drilling.

    Science.gov (United States)

    Li, Xin; Gao, Deli; Chen, Xuyue

    2017-06-08

    Hydraulic extended-reach limit (HERL) model of horizontal extended-reach well (ERW) can predict the maximum measured depth (MMD) of the horizontal ERW. The HERL refers to the well's MMD when drilling fluid cannot be normally circulated by drilling pump. Previous model analyzed the following two constraint conditions, drilling pump rated pressure and rated power. However, effects of the allowable range of drilling fluid flow rate (Q min  ≤ Q ≤ Q max ) were not considered. In this study, three cases of HERL model are proposed according to the relationship between allowable range of drilling fluid flow rate and rated flow rate of drilling pump (Q r ). A horizontal ERW is analyzed to predict its HERL, especially its horizontal-section limit (L h ). Results show that when Q min  ≤ Q r  ≤ Q max (Case I), L h depends both on horizontal-section limit based on rated pump pressure (L h1 ) and horizontal-section limit based on rated pump power (L h2 ); when Q min  < Q max  < Q r (Case II), L h is exclusively controlled by L h1 ; while L h is only determined by L h2 when Q r  < Q min  < Q max (Case III). Furthermore, L h1 first increases and then decreases with the increase in drilling fluid flow rate, while L h2 keeps decreasing as the drilling fluid flow rate increases. The comprehensive model provides a more accurate prediction on HERL.

  16. Test-retest reliability of expiratory abdominal compression with a handheld dynamometer in patients with prolonged mechanical ventilation.

    Science.gov (United States)

    Morino, Akira; Shida, Masahiro; Tanaka, Masashi; Sato, Kimihiro; Seko, Toshiaki; Ito, Shunsuke; Ogawa, Shunichi; Takahashi, Naoaki

    2015-07-01

    [Purpose] The present study aimed to examine the test-retest reliability of expiratory abdominal compression with a handheld dynamometer in patients with prolonged mechanical ventilation. [Subjects and Methods] We recruited 18 patients with prolonged mechanical ventilation. All patients had impaired consciousness. The mode of the ventilator was synchronized intermittent mandatory ventilation. The abdomen above the navel was vertically compressed using a handheld dynamometer in synchronization with expiration. Expiratory abdominal compression was performed two times. We measured the tidal volume during expiratory abdominal compression. There was an interval of 5 minutes between the first and second measurements. Intraclass correlation coefficient (ICC) and Bland-Altman analysis were performed to examine the test-retest reliability of expiratory abdominal compression with a handheld dynamometer. [Results] The test-retest reliability of expiratory abdominal compression was excellent (ICC(1, 1): 0.987). Bland-Altman analysis showed that there was no fixed bias and no proportional bias. [Conclusion] The findings of this study suggest that expiratory abdominal compression with a handheld dynamometer is reliable and useful for patients with respiratory failure and prolonged mechanical ventilation.

  17. Positive end-expiratory pressure (PEEP) does not depress left ventricular function in patients with pulmonary edema

    International Nuclear Information System (INIS)

    Calvin, J.E.; Driedger, A.A.; Sibbald, W.J.

    1981-01-01

    Researchers evaluated the effects of positive end-expiratory pressure (PEEP) on left ventricular function in 15 patients with acute respiratory insufficiency secondary to pulmonary edema with invasive (pressure; flow) measurements and radionuclide angiography (RA). Using RNA allowed a definition of the left ventricular ejection fraction (LVEF), and then calculation of the left ventricular end-diastolic volume (LVEDV), both before and after PEEP. With a mean PEEP of 14.2 +/- 1.8 cm H2O (mean +/- SD) (range, 10 to 15), a fall in the cardiac index (4.34 +/- 1.5 to 3.84 +/- 1.4 L/min/M2; p less than 0.001) was accompanied by a significant decrease in the stroke volume index (42 +/- 13 to 39 +/- 12 ml/beat M2; p less than 0.01) and pulse rate (103.4 +/- 14.3 to 98 +/- 13.5 beats/min; p less than 0.01). The decrease in the stroke volume index was primarily due to a significant decrease in left ventricular preload (LVEDV) from 85.9 +/- 19 to 71.4 +/- 21.4 ml/m2 (p less than 0.01). Simultaneously, the mean LVEF increased from 0.47 +/- 0.10 to 0.53 +/- 0.08 (p less than 0.05), despite a significant increase in the systemic vascular resistance (1,619 +/- 575 to 1,864 +/- 617 dynes . s. cm-5/M2; p less than 0.01). Researchers concluded that the use of PEEP in patients with acute pulmonary edema, to the degree used in this study, may depress cardiac output by simply decreasing left ventricular preload. Researchers were unable to produce any evidence that would support a change in the contractile state of the left ventricle as a cause of depressed forward flow with the use of PEEP

  18. Blood flow and vascular reactivity during attacks of classic migraine--limitations of the Xe-133 intraarterial technique

    DEFF Research Database (Denmark)

    Skyhøj Olsen, T; Lassen, N A

    1989-01-01

    The present study reports cerebral blood flow (CBF) measurements in 11 patients during attacks of classic migraine (CM)--migraine with aura. In 6 and 7 patients, respectively, cerebral vascular reactivity to increased blood pressure and to hypocapnia was also investigated during the CM attacks. T...

  19. Limitation of parallel flow in double diffusive convection: Two- and three-dimensional transitions in a horizontal porous domain

    Energy Technology Data Exchange (ETDEWEB)

    Mimouni, N.; Chikh, S.; Rahli, O. [Laboratoire LTPMP, Fac GMGP, USTHB, BP 32, Alia, Bab Ezzouar, Algiers (Algeria); Bennacer, R., E-mail: Rachid.Bennacer@ens-cachan.fr [LMT-ENS Cachan, 61 av. du président Wilson F-94235 Cachan Cedex (France)

    2014-07-15

    Two-dimensional (2D) and three-dimensional (3D) numerical simulations of double diffusion natural convection in an elongated enclosure filled with a binary fluid saturating a porous medium are carried out in the present work. The Boussinesq approximation is made in the formulation of the problem, and Neumann boundary conditions for temperature and concentration are adopted, respectively, on vertical and horizontal walls of the cavity. The used numerical method is based on the control volume approach, with the third order quadratic upstream interpolation scheme in approximating the advection terms. A semi implicit method algorithm is used to handle the velocity-pressure coupling. To avoid the excessively high computer time inherent to the solution of 3D natural convection problems, full approximation storage with full multigrid method is used to solve the problem. A wide range of the controlling parameters (Rayleigh-Darcy number Ra, lateral aspect ratio Ay, Lewis number Le, and the buoyancy ration N) is investigated. We clearly show that increasing the depth of the cavity (i.e., the lateral aspect ratio) has an important effect on the flow patterns. The 2D perfect parallel flows obtained for small lateral aspect ratio are drastically destabilized by increasing the cavity lateral dimension. This yields a 3D fluid motion with a much more complex flow pattern and the usually considered 2D parallel flow model cannot be applied.

  20. Experimental observation and modelling of roughness variation due to supply-limited sediment transport in uni-directional flow

    NARCIS (Netherlands)

    Tuijnder, Arjan; Ribberink, Jan S.

    2012-01-01

    This paper presents a study on the relationship between supply-limited bedform formation and the hydraulic roughness of the riverbed. The results of several new sets of flume experiments with supply-limited or partial transport conditions with bimodal sediment are presented. The results show that

  1. Positive end-expiratory pressure increases pulmonary clearance of inhaled 99mTc-DTPA in nonsmokers but not in healthy smokers

    International Nuclear Information System (INIS)

    Nolop, K.B.; Braude, S.; Royston, D.; Maxwell, D.L.; Hughes, J.M.B.

    1987-01-01

    Positive end-expiratory pressure (PEEP) is widely used in the treatment of severe pulmonary oedema, although its effects on the clearance of water and small solutes from alveolus to blood are not well characterized. We studied the effect of the application of 10 cmH 2 O of PEEP on the flux of inhaled 99 mTc-diethylene-triamine-penta-acetic acid (DTPA) from lung to blood in six healthy smoking and six nonsmoking subjects. The rate of flux was corrected for possible changes in pulmonary blood volume during PEEP by use of an intravenous injection of 99m Tc-DTPA. The baseline clearance rate (K,%.min -1 ) for nonsmokers was 1.48±0.12 (mean±SE) and increased to 2.40±0.29 during PEEP (p<0.05). In contrast, the mean clearance rate for smokers was 3.26±0.82 at baseline and 3.03±0.82 during PEEP (p=NS). The application of positive end-expiratory pressure appears to increase alveolar solute flux in nonsmokers but not in smokers, suggesting that the pathway for solute clearance in smokers is governed by different rate-limiting steps to those of nonsmokers

  2. Effect of Acu-TENS on post-exercise expiratory lung volume in subjects with asthma-A randomized controlled trial.

    Science.gov (United States)

    Ngai, Shirley P C; Jones, Alice Y M; Hui-Chan, Christina W Y; Ko, Fanny W S; Hui, David S C

    2009-07-31

    This study examined the effect of transcutaneous electrical nerve stimulation applied over acupoints (Acu-TENS) on forced expiratory volume, in patients with asthma, after exercise. Thirty subjects were randomly assigned to three groups. Group 1 received Acu-TENS over acupuncture points Lieque and Dingchuan for 45 min prior to a symptom-limited treadmill exercise test. Group 2 had Acu-TENS similarly applied prior to and throughout the exercise test. Group 3 mimicked Group 1 but without any electrical output from the device. Forced expiratory volume in one second (FEV(1)) and forced vital capacity (FVC) were recorded before, immediately after and at 20-min intervals post-exercise for 1h. Immediately after exercise, FEV(1) and FVC rose in Group 2 (p=0.015), but decreased in Group 1 and more so in Group 3. The differences became even more marked at 20, 40 and 60 min. Adjunctive Acu-TENS therapy appears to reduce decline of FEV(1) following exercise training in patients with asthma.

  3. Inspiratory and expiratory muscle training in subacute stroke: A randomized clinical trial.

    Science.gov (United States)

    Messaggi-Sartor, Monique; Guillen-Solà, Anna; Depolo, Marina; Duarte, Esther; Rodríguez, Diego A; Barrera, Maria-Camelia; Barreiro, Esther; Escalada, Ferran; Orozco-Levi, Mauricio; Marco, Ester

    2015-08-18

    To assess the effectiveness, feasibility, and safety of short-term inspiratory and expiratory muscle training (IEMT) in subacute stroke patients. Within 2 weeks of stroke onset, 109 patients with a first ischemic stroke event were randomly assigned to the IEMT (n = 56) or sham IEMT (n = 53) study group. The IEMT consisted of 5 sets of 10 repetitions, twice a day, 5 days per week for 3 weeks, at a training workload equivalent to 30% of maximal respiratory pressures. Patients and researchers assessing outcome variables were blinded to the assigned study group. The main outcome was respiratory muscle strength assessed by maximal inspiratory and expiratory pressures (PImax, PEmax). Respiratory complications at 6 months were also recorded. Both groups improved respiratory muscle strength during the study. IEMT was associated with significantly improved %PImax and %PEmax: effect size d = 0.74 (95% confidence interval [CI] 0.28-1.20) and d = 0.56 (95% CI 0.11-1.02), respectively. No significant training effect was observed for peripheral muscle strength. Respiratory complications at 6 months occurred more frequently in the sham group (8 vs 2, p = 0.042), with an absolute risk reduction of 14%. The number needed to treat to prevent one lung infection event over a follow-up of 6 months was 7. No major adverse events or side effects were observed. IEMT induces significant improvement in inspiratory and expiratory muscle strength and could potentially offer an additional therapeutic tool aimed to reduce respiratory complications at 6 months in stroke patients. This study provides Class II evidence that short-term training may have the potential to improve respiratory muscle strength in patients with subacute stroke. © 2015 American Academy of Neurology.

  4. Effect of pilates method on inspiratory and expiratory muscle strength in the elderly

    Directory of Open Access Journals (Sweden)

    Beatriz Mendes Tozim

    2018-03-01

    Full Text Available With aging, the respiratory muscle strength decreases and the pilates method is a technique that uses respiration as one of its principles. The present study has the aim of analyzing the influence of the pilates method on respiratory muscle strength in older women. For the evaluation of respiratory muscle strength (inspiratory and expiratory, manovacuometer was used. Thirty-one older women were divided into two groups: 14 participated in the pilates group and 17 in the control group. Participants of the pilates group performed 16 sessions of pilates method with an hour of training, twice week for eight weeks. The control group participated in four educational lectures for eight weeks. For statistical analysis, Shapiro-Wilk, ANOVA for repeated measures (p <0.05 and Cohen’s D index were performed. The results showed significant difference and the mean effect for the Cohen’s D index expiratory muscle strength of the pilates group when comparing before (69.71 ± 25.48 and after (85.23 ± 22.21 training (p<0.05 with an increase of 23%. The results of inspiratory muscle strength were not significant but presented an average effect for the Cohen’s D index for the pilates group before (69.71 ± 35.46 and after (88.00 ± 34.87 training, with an increase of 27%. The control group did not present significant differences for the variables evaluated. It could be concluded that the pilates method is effective in improving expiratory muscle strength and provides positive effects on the increase in inspiratory muscle strength.

  5. Unidirectional Expiratory Valve Method to Assess Maximal Inspiratory Pressure in Individuals without Artificial Airway.

    Directory of Open Access Journals (Sweden)

    Samantha Torres Grams

    Full Text Available Maximal Inspiratory Pressure (MIP is considered an effective method to estimate strength of inspiratory muscles, but still leads to false positive diagnosis. Although MIP assessment with unidirectional expiratory valve method has been used in patients undergoing mechanical ventilation, no previous studies investigated the application of this method in subjects without artificial airway.This study aimed to compare the MIP values assessed by standard method (MIPsta and by unidirectional expiratory valve method (MIPuni in subjects with spontaneous breathing without artificial airway. MIPuni reproducibility was also evaluated.This was a crossover design study, and 31 subjects performed MIPsta and MIPuni in a random order. MIPsta measured MIP maintaining negative pressure for at least one second after forceful expiration. MIPuni evaluated MIP using a unidirectional expiratory valve attached to a face mask and was conducted by two evaluators (A and B at two moments (Tests 1 and 2 to determine interobserver and intraobserver reproducibility of MIP values. Intraclass correlation coefficient (ICC[2,1] was used to determine intraobserver and interobserver reproducibility.The mean values for MIPuni were 14.3% higher (-117.3 ± 24.8 cmH2O than the mean values for MIPsta (-102.5 ± 23.9 cmH2O (p<0.001. Interobserver reproducibility assessment showed very high correlation for Test 1 (ICC[2,1] = 0.91, and high correlation for Test 2 (ICC[2,1] = 0.88. The assessment of the intraobserver reproducibility showed high correlation for evaluator A (ICC[2,1] = 0.86 and evaluator B (ICC[2,1] = 0.77.MIPuni presented higher values when compared with MIPsta and proved to be reproducible in subjects with spontaneous breathing without artificial airway.

  6. Significant, but limited collateral blood flow increases occur with prolonged training in rats with femoral artery occlusion.

    Science.gov (United States)

    Prior, B M; Ren, J; Terjung, R L; Yang, H T

    2011-04-01

    This study examined the capacity of collateral dependent blood flow induced by a prolonged treadmill training program, as compared to a low collateral resistance model created by femoral artery to vein (A-V) shunt. Sprague-Dawley rats, with bilateral femoral artery occlusion were confined to cage activity (Sed, n=9) or trained by daily treadmill exercise (Tr, n=15; up to ≈350 min/d) for 15 weeks. Another set of animals received a femoral A-V anastomosis in one limb and treated with (n=4) or without VEGF(165) (n=9) infusion for 2 weeks. The contralateral side was used as control. Blood flow (BF) was measured with isotope labeled microspheres. Maximal calf muscle BF increased by 15 week training (up to 100±5.0 ml x min(-1) x 100g(-1) (ptraining programs used previously. In contrast, femoral A-V shunt with VEGF(165) increased calf muscle conductance to 1.70±0.3 ml x min(-1) x 100 g(-1) x mmHg(-1) that is similar to blood flows observed in non-occluded rats during maximal running. Our data indicate that the collateral circuit development is related to the driving stimulus and that exercise training, does not provide a maximal stimulus for adaptation that is possible. Nonetheless, exercise training results in profound increases in exercise capacity associated with this enhanced collateral blood flow. Our results illustrate that vascular adaptations can be much greater when physiologically induced stimuli are enhanced at the time of therapeutic angiogenesis.

  7. The Kölliker-Fuse nucleus orchestrates the timing of expiratory abdominal nerve bursting.

    Science.gov (United States)

    Barnett, William H; Jenkin, Sarah E M; Milsom, William K; Paton, Julian F R; Abdala, Ana P; Molkov, Yaroslav I; Zoccal, Daniel B

    2018-02-01

    Coordination of respiratory pump and valve muscle activity is essential for normal breathing. A hallmark respiratory response to hypercapnia and hypoxia is the emergence of active exhalation, characterized by abdominal muscle pumping during the late one-third of expiration (late-E phase). Late-E abdominal activity during hypercapnia has been attributed to the activation of expiratory neurons located within the parafacial respiratory group (pFRG). However, the mechanisms that control emergence of active exhalation, and its silencing in restful breathing, are not completely understood. We hypothesized that inputs from the Kölliker-Fuse nucleus (KF) control the emergence of late-E activity during hypercapnia. Previously, we reported that reversible inhibition of the KF reduced postinspiratory (post-I) motor output to laryngeal adductor muscles and brought forward the onset of hypercapnia-induced late-E abdominal activity. Here we explored the contribution of the KF for late-E abdominal recruitment during hypercapnia by pharmacologically disinhibiting the KF in in situ decerebrate arterially perfused rat preparations. These data were combined with previous results and incorporated into a computational model of the respiratory central pattern generator. Disinhibition of the KF through local parenchymal microinjections of gabazine (GABA A receptor antagonist) prolonged vagal post-I activity and inhibited late-E abdominal output during hypercapnia. In silico, we reproduced this behavior and predicted a mechanism in which the KF provides excitatory drive to post-I inhibitory neurons, which in turn inhibit late-E neurons of the pFRG. Although the exact mechanism proposed by the model requires testing, our data confirm that the KF modulates the formation of late-E abdominal activity during hypercapnia. NEW & NOTEWORTHY The pons is essential for the formation of the three-phase respiratory pattern, controlling the inspiratory-expiratory phase transition. We provide

  8. Bench and mathematical modeling of the effects of breathing a helium/oxygen mixture on expiratory time constants in the presence of heterogeneous airway obstructions

    Directory of Open Access Journals (Sweden)

    Martin Andrew R

    2012-05-01

    Full Text Available Abstract Background Expiratory time constants are used to quantify emptying of the lung as a whole, and emptying of individual lung compartments. Breathing low-density helium/oxygen mixtures may modify regional time constants so as to redistribute ventilation, potentially reducing gas trapping and hyperinflation for patients with obstructive lung disease. In the present work, bench and mathematical models of the lung were used to study the influence of heterogeneous patterns of obstruction on compartmental and whole-lung time constants. Methods A two-compartment mechanical test lung was used with the resistance in one compartment held constant, and a series of increasing resistances placed in the opposite compartment. Measurements were made over a range of lung compliances during ventilation with air or with a 78/22% mixture of helium/oxygen. The resistance imposed by the breathing circuit was assessed for both gases. Experimental results were compared with predictions of a mathematical model applied to the test lung and breathing circuit. In addition, compartmental and whole-lung time constants were compared with those reported by the ventilator. Results Time constants were greater for larger minute ventilation, and were reduced by substituting helium/oxygen in place of air. Notably, where time constants were long due to high lung compliance (i.e. low elasticity, helium/oxygen improved expiratory flow even for a low level of resistance representative of healthy, adult airways. In such circumstances, the resistance imposed by the external breathing circuit was significant. Mathematical predictions were in agreement with experimental results. Time constants reported by the ventilator were well-correlated with those determined for the whole-lung and for the low-resistance compartment, but poorly correlated with time constants determined for the high-resistance compartment. Conclusions It was concluded that breathing a low-density gas mixture, such

  9. Bench and mathematical modeling of the effects of breathing a helium/oxygen mixture on expiratory time constants in the presence of heterogeneous airway obstructions.

    Science.gov (United States)

    Martin, Andrew R; Katz, Ira M; Terzibachi, Karine; Gouinaud, Laure; Caillibotte, Georges; Texereau, Joëlle

    2012-05-30

    Expiratory time constants are used to quantify emptying of the lung as a whole, and emptying of individual lung compartments. Breathing low-density helium/oxygen mixtures may modify regional time constants so as to redistribute ventilation, potentially reducing gas trapping and hyperinflation for patients with obstructive lung disease. In the present work, bench and mathematical models of the lung were used to study the influence of heterogeneous patterns of obstruction on compartmental and whole-lung time constants. A two-compartment mechanical test lung was used with the resistance in one compartment held constant, and a series of increasing resistances placed in the opposite compartment. Measurements were made over a range of lung compliances during ventilation with air or with a 78/22% mixture of helium/oxygen. The resistance imposed by the breathing circuit was assessed for both gases. Experimental results were compared with predictions of a mathematical model applied to the test lung and breathing circuit. In addition, compartmental and whole-lung time constants were compared with those reported by the ventilator. Time constants were greater for larger minute ventilation, and were reduced by substituting helium/oxygen in place of air. Notably, where time constants were long due to high lung compliance (i.e. low elasticity), helium/oxygen improved expiratory flow even for a low level of resistance representative of healthy, adult airways. In such circumstances, the resistance imposed by the external breathing circuit was significant. Mathematical predictions were in agreement with experimental results. Time constants reported by the ventilator were well-correlated with those determined for the whole-lung and for the low-resistance compartment, but poorly correlated with time constants determined for the high-resistance compartment. It was concluded that breathing a low-density gas mixture, such as helium/oxygen, can improve expiratory flow from an obstructed

  10. Study of counter current flow limitation model of MARS-KS and SPACE codes under Dukler's air/water flooding test conditions

    International Nuclear Information System (INIS)

    Lee, Won Woong; Kim, Min Gil; Lee, Jeong Ik; Bang, Young Seok

    2015-01-01

    In particular, CCFL(the counter current flow limitation) occurs in components such as hot leg, downcomer annulus and steam generator inlet plenum during LOCA which is possible to have flows in two opposite directions. Therefore, CCFL is one of the thermal-hydraulic models which has significant effect on the reactor safety analysis code performance. In this study, the CCFL model will be evaluated with MARS-KS based on two-phase two-field governing equations and SPACE code based on two-phase three-field governing equations. This study will be conducted by comparing MARS-KS code which is being used for evaluating the safety of a Korean Nuclear Power Plant and SPACE code which is currently under assessment for evaluating the safety of the designed nuclear power plant. In this study, comparison of the results of liquid upflow and liquid downflow rate for different gas flow rate from two code to the famous Dukler's CCFL experimental data are presented. This study will be helpful to understand the difference between system analysis codes with different governing equations, models and correlations, and further improving the accuracy of system analysis codes. In the nuclear reactor system, CCFL is an important phenomenon for evaluating the safety of nuclear reactors. This is because CCFL phenomenon can limit injection of ECCS water when CCFL occurs in components such as hot leg, downcomer annulus or steam generator inlet plenum during LOCA which is possible to flow in two opposite directions. Therefore, CCFL is one of the thermal-hydraulic models which has significant effect on the reactor safety analysis code performance. In this study, the CCFL model was evaluated with MARS-KS and SPACE codes for studying the difference between system analysis codes with different governing equations, models and correlations. This study was conducted by comparing MARS-KS and SPACE code results of liquid upflow and liquid downflow rate for different gas flow rate to the famous Dukler

  11. Tidal breathing flow-volume loop analysis for clinical assessment of airway obstruction in conscious dogs.

    Science.gov (United States)

    Amis, T C; Kurpershoek, C

    1986-05-01

    Using a mask, pneumotachograph, and X-Y recorder, tidal breathing flow-volume loops (TBFVL) were evaluated in 33 healthy dogs and in 18 dogs with acquired obstructive respiratory tract disease. The loops were evaluated for qualitative shape, tidal volume (VT), respiratory rate, peak and midtidal inspiratory flow (PIF and IF50, respectively), peak and midtidal expiratory flow (PEF and EF50, respectively), inspiratory and expiratory flow at end expiratory volume plus 25% VT (IF25 and EF25, respectively), inspiratory time, and expiratory time. Indices of loop shape were developed by division of flow measurements (eg, PEF/PIF and IF50/IF25). Twenty healthy dogs had the same TBFVL (type 1). Typically, PEF occurred at the beginning of expiration, and PIF occurred toward the end of inspiration. Three other TBFVL types were identified in the remaining dogs. Mean coefficients of variation for TBFVL indices ranged from 7% to 18%. Dogs with a fixed-type upper airway obstruction (pharyngeal or laryngeal mass, n = 7) had TBFVL abnormalities, indicating inspiratory and expiratory phase flattening. Concavity or late expiratory phase flattening was detected in TBFVL from dogs with chronic bronchitis/tracheal collapse (n = 11). The TBFVL were easily evaluated in conscious dogs and were useful in the functional assessment of airway obstruction.

  12. Longitudinal pressure-driven flows between superhydrophobic grooved surfaces: Large effective slip in the narrow-channel limit

    Science.gov (United States)

    Schnitzer, Ory; Yariv, Ehud

    2017-07-01

    The gross amplification of the fluid velocity in pressure-driven flows due to the introduction of superhydrophobic walls is commonly quantified by an effective slip length. The canonical duct-flow geometry involves a periodic structure of longitudinal shear-free stripes at either one or both of the bounding walls, corresponding to flat-meniscus gas bubbles trapped within a periodic array of grooves. This grating configuration is characterized by two geometric parameters, namely the ratio κ of channel width to microstructure period and the areal fraction Δ of the shear-free stripes. For wide channels, κ ≫1 , this geometry is known to possess an approximate solution where the dimensionless slip length λ , normalized by the duct semiwidth, is small, indicating a weak superhydrophobic effect. We here address the other extreme of narrow channels, κ ≪1 , identifying large O (κ-2) values of λ for the symmetric configuration, where both bounding walls are superhydrophobic. This velocity enhancement is associated with an unconventional Poiseuille-like flow profile where the parabolic velocity variation takes place in a direction parallel (rather than perpendicular) to the boundaries. Use of matched asymptotic expansions and conformal-mapping techniques provides λ up to O (κ-1) , establishing the approximationλ ˜κ-2Δ/33 +κ-1Δ/2π ln4 +⋯, which is in excellent agreement with a semianalytic solution of the dual equations governing the respective coefficients of a Fourier-series representation of the fluid velocity. No similar singularity occurs in the corresponding asymmetric configuration, involving a single superhydrophobic wall; in that geometry, a Hele-Shaw approximation shows that λ =O (1 ) .

  13. Pressure Drop Versus Flow Rate Analysis of the Limited Streamer Tube Gas System of the BaBar Muon Detector Upgrade

    International Nuclear Information System (INIS)

    Yi, M.

    2004-01-01

    It has been proposed that Limited Streamer Tubes (LST) be used in the current upgrade of the muon detector in the BaBar detector. An LST consists of a thin silver plated wire centered in a graphite-coated cell. One standard LST tube consists of eight such cells, and two or three such tubes form an LST module. Under operation, the cells are filled with a gas mixture of CO 2 , argon and isobutane. During normal operation of the detector, the gas will be flushed out of the system at a constant low rate of one volume change per day. During times such as installation, however, it is often desired to flush and change the LST gas volumes very rapidly, leading to higher than normal pressure which may damage the modules. This project studied this pressure as a function of flow rate and the number of modules that are put in series in search of the maximal safe flow rate at which to flush the modules. Measurements of pressure drop versus flow rate were taken using a flow meter and a pressure transducer on configurations of one to five modules put in series. Minimal Poly-Flo tubing was used for all connections between test equipment and modules. They contributed less than 25% to all measurements. A ratio of 0.00022 ± 0.00001 mmHg per Standard Cubic Centimeter per Minute (SCCM) per module was found, which was a slight overestimate since it included the contributions from the tubing connections. However, for the purpose of finding a flow rate at which the modules can be safely flushed, this overestimate acts as a safety cushion. For a standard module with a volume of 16 liters and a known safe overpressure of 2 inches of water, the ratio translates into a flow rate of 17000 ± 1000SCCM and a time requirement of 56 ± 5 seconds to flush an entire module

  14. Effect of the radiofrequency volumetric tissue reduction of inferior turbinate on expiratory nasal sound frequency.

    Science.gov (United States)

    Seren, Erdal

    2009-01-01

    We sought to evaluate the short-term efficacy of radiofrequency volumetric tissue reduction (RFVTR) in treatment of inferior turbinate hypertrophy (TH) as measured by expiratory nasal sound spectra. In our study, we aimed to investigate the Odiosoft-rhino (OR) as a new diagnostic method to evaluate the nasal airflow of patients before and after RFVTR. In this study, we have analyzed and recorded the expiratory nasal sound in patients with inferior TH before and after RFVTR. This analysis includes the time expanded waveform, the spectral analysis with time averaged fast Fourier transform (FFT), and the waveform analysis of nasal sound. We found an increase in sound intensity at high frequency (Hf) in the sound analyses of the patients before RFVTR and a decrease in sound intensity at Hf was found in patients after RFVTR. This study indicates that RFVTR is an effective procedure to improve nasal airflow in the patients with nasal obstruction with inferior TH. We found significant decreases in the sound intensity level at Hf in the sound spectra after RFVTR. The OR results from the 2000- to 4000-Hz frequency (Hf) interval may be more useful in assessing patients with nasal obstruction than other frequency intervals. OR may be used as a noninvasive diagnostic tool to evaluate the nasal airflow.

  15. Control of positive end-expiratory pressure (PEEP for small animal ventilators

    Directory of Open Access Journals (Sweden)

    Leão Nunes Marcelo V

    2010-07-01

    Full Text Available Abstract Background The positive end-expiratory pressure (PEEP for the mechanical ventilation of small animals is frequently obtained with water seals or by using ventilators developed for human use. An alternative mechanism is the use of an on-off expiratory valve closing at the moment when the alveolar pressure is equal to the target PEEP. In this paper, a novel PEEP controller (PEEP-new and the PEEP system of a commercial small-animal ventilator, both based on switching an on-off valve, are evaluated. Methods The proposed PEEP controller is a discrete integrator monitoring the error between the target PEEP and the airways opening pressure prior to the onset of an inspiratory cycle. In vitro as well as in vivo experiments with rats were carried out and the PEEP accuracy, settling time and under/overshoot were considered as a measure of performance. Results The commercial PEEP controller did not pass the tests since it ignores the airways resistive pressure drop, resulting in a PEEP 5 cmH2O greater than the target in most conditions. The PEEP-new presented steady-state errors smaller than 0.5 cmH2O, with settling times below 10 s and under/overshoot smaller than 2 cmH2O. Conclusion The PEEP-new presented acceptable performance, considering accuracy and temporal response. This novel PEEP generator may prove useful in many applications for small animal ventilators.

  16. Benefit of educational feedback for the use of positive expiratory pressure device

    Science.gov (United States)

    Reychler, Gregory; Jacquemart, Manon; Poncin, William; Aubriot, Anne-Sophie; Liistro, Giuseppe

    2015-01-01

    BACKGROUND: Positive expiratory pressure (PEP) is regularly used as a self-administered airway clearance technique. OBJECTIVE: The aim of this study was to evaluate the need to teach the correct use of the PEP device and to measure the progress of the success rate of the maneuver after training. METHOD: A PEP system (PariPEP-S Sytem) was used to generate PEP in 30 healthy volunteers. They were instructed by a qualified physical therapist to breathe correctly through the PEP device. Then they were evaluated during a set of ten expirations. Two other evaluations were performed at day 2 and day 8 (before and after feedback). The mean PEP and the success rate were calculated for each set of expirations. The number of maneuvers needed to obtain a correct use was calculated on the first session. RESULTS: An optimal PEP was reached after 7.5 SD 2.7 attempts by all subjects. Success rates and mean pressures were similar between the different sets of expirations (p=0.720 and p=0.326, respectively). Pressure variability was around 10%. After one week, 30% of subjects generated more than two non-optimal pressures in the set of ten expirations. No difference in success rate was observed depending on the evaluations. CONCLUSION: This study demonstrates that good initial training on the use of the PEP device and regular follow-up are required for the subject to reach optimal expiratory pressure. PMID:26647746

  17. Relationship of end-expiratory pressure, lung volume, and /sup 99m/Tc-DTPA clearance

    International Nuclear Information System (INIS)

    Cooper, J.A.; van der Zee, H.; Line, B.R.; Malik, A.B.

    1987-01-01

    We investigated the dose-response effect of positive end-expiratory pressure (PEEP) and increased lung volume on the pulmonary clearance rate of aerosolized technetium-99m-labeled diethylenetriaminepentaacetic acid (99mTc-DTPA). Clearance of lung radioactivity was expressed as percent decrease per minute. Base-line clearance was measured while anesthetized sheep (n = 20) were ventilated with 0 cmH 2 O end-expiratory pressure. Clearance was remeasured during ventilation at 2.5, 5, 10, 15, or 20 cmH 2 O PEEP. Further studies showed stepwise increases in functional residual capacity (FRC) (P less than 0.05) measured at 0, 2.5, 5, 10, 15, and 20 cmH 2 O PEEP. At 2.5 cmH 2 O PEEP, the clearance rate was not different from that at base line (P less than 0.05), although FRC was increased from base line. Clearance rate increased progressively with increasing PEEP at 5, 10, and 15 cmH 2 O (P less than 0.05). Between 15 and 20 cmH 2 O PEEP, clearance rate was again unchanged, despite an increase in FRC. The pulmonary clearance of aerosolized /sup 99m/Tc-DTPA shows a sigmoidal response to increasing FRC and PEEP, having both threshold and maximal effects. This relationship is most consistent with the hypothesis that alveolar epithelial permeability is increased by lung inflation

  18. Focal cerebral ischemia measured by the intra-arterial 133xenon method. Limitations of 2-dimensional blood flow measurements

    DEFF Research Database (Denmark)

    Skyhøj Olsen, T; Larsen, B; Bech Skriver, E

    1981-01-01

    The limitations of 2-dimensional isotope techniques in the study of focal cerebral ischemia were investigated using the intra-carotid 133 xenon injection method and a 254 multidetector scintillation camera. To make sure that the detectors "look" directly on infarcted areas, only patients with inf...

  19. High flow nasal cannula for respiratory support in preterm infants.

    LENUS (Irish Health Repository)

    Wilkinson, Dominic

    2011-01-01

    High flow nasal cannulae (HFNC) are small, thin, tapered cannulae used to deliver oxygen or blended oxygen and air at flow rates of > 1 L\\/min. HFNC can be used to provide high concentrations of oxygen and may deliver positive end-expiratory pressure.

  20. FLAVODIIRON2 and FLAVODIIRON4 Proteins Mediate an Oxygen-Dependent Alternative Electron Flow in Synechocystis sp. PCC 6803 under CO2-Limited Conditions1[OPEN

    Science.gov (United States)

    Shimakawa, Ginga; Shaku, Keiichiro; Nishi, Akiko; Hayashi, Ryosuke; Yamamoto, Hiroshi; Sakamoto, Katsuhiko; Makino, Amane; Miyake, Chikahiro

    2015-01-01

    This study aims to elucidate the molecular mechanism of an alternative electron flow (AEF) functioning under suppressed (CO2-limited) photosynthesis in the cyanobacterium Synechocystis sp. PCC 6803. Photosynthetic linear electron flow, evaluated as the quantum yield of photosystem II [Y(II)], reaches a maximum shortly after the onset of actinic illumination. Thereafter, Y(II) transiently decreases concomitantly with a decrease in the photosynthetic oxygen evolution rate and then recovers to a rate that is close to the initial maximum. These results show that CO2 limitation suppresses photosynthesis and induces AEF. In contrast to the wild type, Synechocystis sp. PCC 6803 mutants deficient in the genes encoding FLAVODIIRON2 (FLV2) and FLV4 proteins show no recovery of Y(II) after prolonged illumination. However, Synechocystis sp. PCC 6803 mutants deficient in genes encoding proteins functioning in photorespiration show AEF activity similar to the wild type. In contrast to Synechocystis sp. PCC 6803, the cyanobacterium Synechococcus elongatus PCC 7942 has no FLV proteins with high homology to FLV2 and FLV4 in Synechocystis sp. PCC 6803. This lack of FLV2/4 may explain why AEF is not induced under CO2-limited photosynthesis in S. elongatus PCC 7942. As the glutathione S-transferase fusion protein overexpressed in Escherichia coli exhibits NADH-dependent oxygen reduction to water, we suggest that FLV2 and FLV4 mediate oxygen-dependent AEF in Synechocystis sp. PCC 6803 when electron acceptors such as CO2 are not available. PMID:25540330

  1. Effect of simultaneous application of postural techniques and expiratory muscle strength training on the enhancement of the swallowing function of patients with dysphagia caused by parkinson's disease.

    Science.gov (United States)

    Byeon, Haewon

    2016-06-01

    [Purpose] This study aimed to investigate the effect of simultaneous application of postural techniques and expiratory muscle strength training on the enhancement of the swallowing function of patients with dysphagia caused by Parkinson's disease. [Subjects and Methods] The subjects of this study were 18 patients who received simultaneous application of postural techniques and expiratory muscle strength training and 15 patients who received expiratory muscle strength training only. Postural techniques were conducted in the order of chin tucking, head rotation, head tilting, bending head back, and lying down, while expiratory muscle strength training was conducted at a resistance level of about 70% of the maximal expiratory pressure. Swallowing recovery was assessed by using the Functional Dysphagia Scale based on videofluoroscopic studies. [Results] The mean value obtained in the videofluoroscopic studies for both groups decreased after the treatment. In the postural techniques plus expiratory muscle strength training group, the decrease was significantly greater than that in the expiratory muscle strength training-only group. [Conclusion] The results imply that simultaneous performance of postural techniques and expiratory muscle strength training is more effective than expiratory muscle strength training alone when applied in the swallowing rehabilitation for patients with dysphagia caused by Parkinson's disease.

  2. Using an expiratory resistor, arterial pulse pressure variations predict fluid responsiveness during spontaneous breathing: an experimental porcine study.

    Science.gov (United States)

    Dahl, Michael K; Vistisen, Simon T; Koefoed-Nielsen, Jacob; Larsson, Anders

    2009-01-01

    Fluid responsiveness prediction is difficult in spontaneously breathing patients. Because the swings in intrathoracic pressure are minor during spontaneous breathing, dynamic parameters like pulse pressure variation (PPV) and systolic pressure variation (SPV) are usually small. We hypothesized that during spontaneous breathing, inspiratory and/or expiratory resistors could induce high arterial pressure variations at hypovolemia and low variations at normovolemia and hypervolemia. Furthermore, we hypothesized that SPV and PPV could predict fluid responsiveness under these conditions. Eight prone, anesthetized and spontaneously breathing pigs (20 to 25 kg) were subjected to a sequence of 30% hypovolemia, normovolemia, and 20% and 40% hypervolemia. At each volemic level, the pigs breathed in a randomized order either through an inspiratory and/or an expiratory threshold resistor (7.5 cmH2O) or only through the tracheal tube without any resistor. Hemodynamic and respiratory variables were measured during the breathing modes. Fluid responsiveness was defined as a 15% increase in stroke volume (DeltaSV) following fluid loading. Stroke volume was significantly lower at hypovolemia compared with normovolemia, but no differences were found between normovolemia and 20% or 40% hypervolemia. Compared with breathing through no resistor, SPV was magnified by all resistors at hypovolemia whereas there were no changes at normovolemia and hypervolemia. PPV was magnified by the inspiratory resistor and the combined inspiratory and expiratory resistor. Regression analysis of SPV or PPV versus DeltaSV showed the highest R2 (0.83 for SPV and 0.52 for PPV) when the expiratory resistor was applied. The corresponding sensitivity and specificity for prediction of fluid responsiveness were 100% and 100%, respectively, for SPV and 100% and 81%, respectively, for PPV. Inspiratory and/or expiratory threshold resistors magnified SPV and PPV in spontaneously breathing pigs during hypovolemia

  3. Water Saturation Relations and Their Diffusion-Limited Equilibration in Gas Shale: Implications for Gas Flow in Unconventional Reservoirs

    Science.gov (United States)

    Tokunaga, Tetsu K.; Shen, Weijun; Wan, Jiamin; Kim, Yongman; Cihan, Abdullah; Zhang, Yingqi; Finsterle, Stefan

    2017-11-01

    Large volumes of water are used for hydraulic fracturing of low permeability shale reservoirs to stimulate gas production, with most of the water remaining unrecovered and distributed in a poorly understood manner within stimulated regions. Because water partitioning into shale pores controls gas release, we measured the water saturation dependence on relative humidity (rh) and capillary pressure (Pc) for imbibition (adsorption) as well as drainage (desorption) on samples of Woodford Shale. Experiments and modeling of water vapor adsorption into shale laminae at rh = 0.31 demonstrated that long times are needed to characterize equilibrium in larger (5 mm thick) pieces of shales, and yielded effective diffusion coefficients from 9 × 10-9 to 3 × 10-8 m2 s-1, similar in magnitude to the literature values for typical low porosity and low permeability rocks. Most of the experiments, conducted at 50°C on crushed shale grains in order to facilitate rapid equilibration, showed significant saturation hysteresis, and that very large Pc (˜1 MPa) are required to drain the shales. These results quantify the severity of the water blocking problem, and suggest that gas production from unconventional reservoirs is largely associated with stimulated regions that have had little or no exposure to injected water. Gravity drainage of water from fractures residing above horizontal wells reconciles gas production in the presence of largely unrecovered injected water, and is discussed in the broader context of unsaturated flow in fractures.

  4. TU-CD-BRA-11: Application of Bone Suppression Technique to Inspiratory/expiratory Chest Radiography

    Energy Technology Data Exchange (ETDEWEB)

    Tanaka, R; Sanada, S [Kanazawa University, Kanazawa, Ishikawa (Japan); Sakuta, K; Kawashima, H [Kanazawa University Hospital, Kanazawa, Ishikawa (Japan); Kishitani, Y [TOYO Corporation, Chuoh-ku, Tokyo (Japan)

    2015-06-15

    Purpose: The bone suppression technique based on advanced image processing can suppress the conspicuity of bones on chest radiographs, creating soft tissue images normally obtained by the dual-energy subtraction technique. This study was performed to investigate the usefulness of bone suppression technique in quantitative analysis of pulmonary function in inspiratory/expiratory chest radiography. Methods: Commercial bone suppression image processing software (ClearRead; Riverain Technologies) was applied to paired inspiratory/expiratory chest radiographs of 107 patients (normal, 33; abnormal, 74) to create corresponding bone suppression images. The abnormal subjects had been diagnosed with pulmonary diseases, such as pneumothorax, pneumonia, emphysema, asthma, and lung cancer. After recognition of the lung area, the vectors of respiratory displacement were measured in all local lung areas using a cross-correlation technique. The measured displacement in each area was visualized as displacement color maps. The distribution pattern of respiratory displacement was assessed by comparison with the findings of lung scintigraphy. Results: Respiratory displacement of pulmonary markings (soft tissues) was able to be quantified separately from the rib movements on bone suppression images. The resulting displacement map showed a left-right symmetric distribution increasing from the lung apex to the bottom region of the lung in many cases. However, patients with ventilatory impairments showed a nonuniform distribution caused by decreased displacement of pulmonary markings, which were confirmed to correspond to area with ventilatory impairments found on the lung scintigrams. Conclusion: The bone suppression technique was useful for quantitative analysis of respiratory displacement of pulmonary markings without any interruption of the rib shadows. Abnormal areas could be detected as decreased displacement of pulmonary markings. Inspiratory/expiratory chest radiography combined

  5. Properties of end-expiratory breath hold responses measured with near-infrared spectroscopy

    Science.gov (United States)

    Virtanen, Jaakko; Noponen, Tommi; Ilmoniemi, Risto J.

    2011-02-01

    Near-infrared spectroscopy (NIRS) can be used to assess the cerebrovascular response to breath hold. We measured eight healthy subjects during voluntary end-expiratory breath hold to study inter- and intraindividual variability of the deoxy- (HbR) and oxyhemoglobin (HbO2) response curves for the scalp and cerebral cortex. Although cortical [HbO2] behaves qualitatively similarly in all subjects, there is large inter- and intraindividual variability, and in the case of [HbR] also qualitative variability. However, the linearity of [HbO2] increase during the breath hold has encouraging measurement repeatability, and it may even indicate an individual's CO2 tolerance. This result may help understand why breath hold duration varies between subjects more than the total [HbO2] increase during breath hold.

  6. Vagal afferent control of abdominal expiratory activity in response to hypoxia and hypercapnia in rats.

    Science.gov (United States)

    Lemes, Eduardo V; Zoccal, Daniel B

    2014-11-01

    In the present study, we tested the hypothesis that vagal afferent information modulates the pattern of expiratory response to hypercapnia and hypoxia. Simultaneous recordings of airflow, diaphragmatic (DIA) and oblique abdominal muscle (ABD) activities were performed in anesthetized (urethane, 1.2g/kg), tracheostomized, spontaneously breathing male Wistar rats (290-320g, n=12). The animals were exposed to hypercapnia (7 and 10% CO2 for 5min) and hypoxia (7% O2 for 1min) before and after bilateral vagotomy. We verified that the percentage increase in DIA burst amplitude elicited by hypercapnia and hypoxia episodes was similar between intact and vagotomized rats (P>0.05). In contrast, hypercapnia and hypoxia promoted a marked increase in ABD activity in vagotomized, but not in intact rats (Phypoxia in rats. Copyright © 2014 Elsevier B.V. All rights reserved.

  7. THE KÖLLIKER–FUSE NUCLEUS ACTS AS A TIMEKEEPER FOR LATE-EXPIRATORY ABDOMINAL ACTIVITY

    Science.gov (United States)

    JENKIN, SARAH E. M.; MILSOM, WILLIAM K.; ZOCCAL, DANIEL B.

    2018-01-01

    While the transition from the inspiratory to the post-inspiratory (post-I) phase is dependent on the pons, little attention has been paid to understanding the role of the pontine respiratory nuclei, specifically the Kölliker–Fuse nucleus (KF), in transitioning from post-I to the late expiratory (late-E) activity seen with elevated respiratory drive. To elucidate this, we used the in situ working heart-brainstem preparation of juvenile male Holtzman rats and recorded from the vagus (cVN), phrenic (PN) and abdominal nerves (AbN) during baseline conditions and during chemoreflex activation [with potassium cyanide (KCN; n = 13) or hypercapnia (8% CO2; n = 10)] to recruit active expiration. Chemoreflex activation with KCN increased PN frequency and cVN post-I and AbN activities. The inhibition of KF with isoguvacine microinjections (10 mM) attenuated the typical increase in PN frequency and cVN post-I activity, and amplified the AbN response. During hypercapnia, AbN late-E activity emerged in association with a significant reduction in expiratory time. KF inhibition during hypercapnia significantly decreased PN frequency and reduced the duration and amplitude of post-I cVN activity, while the onset of the AbN late-E bursts occurred significantly earlier. Our data reveal a negative relationship between KF-induced post-I and AbN late-E activities, suggesting that the KF coordinates the transition between post-I to late-E activity during conditions of elevated respiratory drive. PMID:28188852

  8. Some infant ventilators do not limit peak inspiratory pressure reliably during active expiration.

    Science.gov (United States)

    Kirpalani, H; Santos-Lyn, R; Roberts, R

    1988-09-01

    In order to minimize barotrauma in newborn infants with respiratory failure, peak inspiratory pressures should not exceed those required for adequate gas exchange. We examined whether four commonly used pressure-limited, constant flow ventilators limit pressure reliably during simulated active expiration against the inspiratory stroke of the ventilator. Three machines of each type were tested at 13 different expiratory flow rates (2 to 14 L/min). Flow-dependent pressure overshoot above a dialed pressure limit of 20 cm H2O was observed in all machines. However, the magnitude differed significantly between ventilators from different manufacturers (p = .0009). Pressure overshoot above 20 cm H2O was consistently lowest in the Healthdyne (0.8 cm H2O at 2 L/min, 3.6 cm H2O at 14 L/min) and highest in the Bourns BP200 (3.0 cm H2O at 2 L/min, 15.4 cm H2O at 14 L/min). We conclude that peak inspiratory pressure overshoots on pressure-limited ventilators occur during asynchronous expiration. This shortcoming may contribute to barotrauma in newborn infants who "fight" positive-pressure ventilation.

  9. Exogenous and endogenous angiotensin‐II decrease renal cortical oxygen tension in conscious rats by limiting renal blood flow

    Science.gov (United States)

    Emans, Tonja W.; Janssen, Ben J.; Pinkham, Maximilian I.; Ow, Connie P. C.; Evans, Roger G.; Joles, Jaap A.; Malpas, Simon C.; Krediet, C. T. Paul

    2016-01-01

    Key points Our understanding of the mechanisms underlying the role of hypoxia in the initiation and progression of renal disease remains rudimentary.We have developed a method that allows wireless measurement of renal tissue oxygen tension in unrestrained rats.This method provides stable and continuous measurements of cortical tissue oxygen tension (PO2) for more than 2 weeks and can reproducibly detect acute changes in cortical oxygenation.Exogenous angiotensin‐II reduced renal cortical tissue PO2 more than equi‐pressor doses of phenylephrine, probably because it reduced renal oxygen delivery more than did phenylephrine.Activation of the endogenous renin–angiotensin system in transgenic Cyp1a1Ren2 rats reduced cortical tissue PO2; in this model renal hypoxia precedes the development of structural pathology and can be reversed acutely by an angiotensin‐II receptor type 1 antagonist.Angiotensin‐II promotes renal hypoxia, which may in turn contribute to its pathological effects during development of chronic kidney disease. Abstract We hypothesised that both exogenous and endogenous angiotensin‐II (AngII) can decrease the partial pressure of oxygen (PO2) in the renal cortex of unrestrained rats, which might in turn contribute to the progression of chronic kidney disease. Rats were instrumented with telemeters equipped with a carbon paste electrode for continuous measurement of renal cortical tissue PO2. The method reproducibly detected acute changes in cortical oxygenation induced by systemic hyperoxia and hypoxia. In conscious rats, renal cortical PO2 was dose‐dependently reduced by intravenous AngII. Reductions in PO2 were significantly greater than those induced by equi‐pressor doses of phenylephrine. In anaesthetised rats, renal oxygen consumption was not affected, and filtration fraction was increased only in the AngII infused animals. Oxygen delivery decreased by 50% after infusion of AngII and renal blood flow (RBF) fell by 3.3 ml min−1

  10. FLAVODIIRON2 and FLAVODIIRON4 proteins mediate an oxygen-dependent alternative electron flow in Synechocystis sp. PCC 6803 under CO2-limited conditions.

    Science.gov (United States)

    Shimakawa, Ginga; Shaku, Keiichiro; Nishi, Akiko; Hayashi, Ryosuke; Yamamoto, Hiroshi; Sakamoto, Katsuhiko; Makino, Amane; Miyake, Chikahiro

    2015-02-01

    This study aims to elucidate the molecular mechanism of an alternative electron flow (AEF) functioning under suppressed (CO2-limited) photosynthesis in the cyanobacterium Synechocystis sp. PCC 6803. Photosynthetic linear electron flow, evaluated as the quantum yield of photosystem II [Y(II)], reaches a maximum shortly after the onset of actinic illumination. Thereafter, Y(II) transiently decreases concomitantly with a decrease in the photosynthetic oxygen evolution rate and then recovers to a rate that is close to the initial maximum. These results show that CO2 limitation suppresses photosynthesis and induces AEF. In contrast to the wild type, Synechocystis sp. PCC 6803 mutants deficient in the genes encoding FLAVODIIRON2 (FLV2) and FLV4 proteins show no recovery of Y(II) after prolonged illumination. However, Synechocystis sp. PCC 6803 mutants deficient in genes encoding proteins functioning in photorespiration show AEF activity similar to the wild type. In contrast to Synechocystis sp. PCC 6803, the cyanobacterium Synechococcus elongatus PCC 7942 has no FLV proteins with high homology to FLV2 and FLV4 in Synechocystis sp. PCC 6803. This lack of FLV2/4 may explain why AEF is not induced under CO2-limited photosynthesis in S. elongatus PCC 7942. As the glutathione S-transferase fusion protein overexpressed in Escherichia coli exhibits NADH-dependent oxygen reduction to water, we suggest that FLV2 and FLV4 mediate oxygen-dependent AEF in Synechocystis sp. PCC 6803 when electron acceptors such as CO2 are not available. © 2015 American Society of Plant Biologists. All Rights Reserved.

  11. Does phase 2 of the expiratory PCO2 versus volume curve have diagnostic value in emphysema patients?

    NARCIS (Netherlands)

    A.H. Kars (Alice); G. Goorden; Th. Stijnen (Theo); J.M. Bogaard (Jan); A.F.M. Verbraak (Anton); C. Hilvering

    1995-01-01

    textabstractIt has been postulated that serial inhomogeneity of ventilation in the peripheral airways in emphysema is represented by the shape of expiratory carbon dioxide tension versus volume curve. We examined the diagnostic value of this test in patients with various degrees of emphysema. The

  12. Does phase 2 of the expiratory PCO2 versus volume curve have diagnostic value in emphysema patients?

    NARCIS (Netherlands)

    A.H. Kars (Alice); G. Goorden; Th. Stijnen (Theo); J.M. Bogaard (Jan); A.F.M. Verbraak (Anton); C. Hilvering

    1995-01-01

    textabstractIt has been postulated that serial inhomogeneity of ventilation in the peripheral airways in emphysema is represented by the shape of expiratory carbon dioxide tension versus volume curve. We examined the diagnostic value of this test in patients with various degrees of

  13. Nebulized hypertonic saline via positive expiratory pressure versus via jet nebulizer in patients with severe cystic fibrosis.

    LENUS (Irish Health Repository)

    O'Connell, Oisin J

    2011-06-01

    Nebulized hypertonic saline is a highly effective therapy for patients with cystic fibrosis (CF), yet 10% of patients are intolerant of hypertonic saline administered via jet nebulizer. Positive expiratory pressure (PEP) nebulizers splint open the airways and offers a more controlled rate of nebulization.

  14. The respiratory drive to thoracic motoneurones in the cat and its relation to the connections from expiratory bulbospinal neurones

    DEFF Research Database (Denmark)

    Saywell, S A; Anissimova, N P; Ford, T W

    2007-01-01

    of connection revealed were related to the presence and size of central respiratory drive potentials in the same motoneurones. Intracellular recordings were made from motoneurones in segments T5-T9 of the spinal cord of anaesthetized cats. Spike-triggered averaging from expiratory bulbospinal neurones...

  15. Improvement of lung mechanics by exogenous surfactant: effect of prior application of high positive end-expiratory pressure

    NARCIS (Netherlands)

    A. Hartog (Anneke); D.A.M.P.J. Gommers (Diederik); J.J. Haitsma (Jack); B.F. Lachmann (Burkhard)

    2000-01-01

    textabstractThe use of a ventilation strategy with high positive end-expiratory pressure (PEEP) that is intended to recruit collapsed alveoli and to prevent recurrent collapse can reduce alveolar protein influx in experimental acute lung injury (ALI). This could affect

  16. Positive end-expiratory pressure improves survival in a rodent model of cardiopulmonary resuscitation using high-dose epinephrine.

    LENUS (Irish Health Repository)

    McCaul, Conán

    2009-10-01

    Multiple interventions have been tested in models of cardiopulmonary resuscitation (CPR) to optimize drug use, chest compressions, and ventilation. None has studied the effects of positive end-expiratory pressure (PEEP) on outcome. We hypothesized that because PEEP can reverse pulmonary atelectasis, lower pulmonary vascular resistance, and potentially improve cardiac output, its use during CPR would increase survival.

  17. Levels of maximum end-expiratory carbon monoxide and certain cardiovascular parameters following hubble-bubble smoking.

    Science.gov (United States)

    Shafagoj, Yanal A; Mohammed, Faisal I

    2002-08-01

    The physiological effects of cigarette smoking have been widely studied, however, little is known regarding the effects of smoking hubble-bubble. We examined the acute effects of hubble-bubble smoking on heart rate, systolic, diastolic, and mean arterial blood pressure and maximum end-expiratory carbon monoxide. This study was carried out in the student laboratory, School of Medicine, Department of Physiology, University of Jordan, Amman, Jordan, during the summer of 1999. In 18 healthy habitual hubble-bubble smokers, heart rate, blood pressure, and maximum end-expiratory carbon monoxide was measured before, during and post smoking of one hubble-bubble run (45 minutes). Compared to base line (time zero), at the end of smoking heart rate, systolic blood pressure, diastolic blood pressure, mean arterial blood pressure, and maximum end-expiratory carbon monoxide were increased 16 2.4 beats per minute, 6.7 2.5 mm Hg, 4.4 1.6 mm Hg, 5.2 1.7 mm Hg, and 14.2 1.8 ppm, (mean standard error of mean, Phubble-bubble smoking elicits a modest increase in heart rate, systolic blood pressure, diastolic blood pressure, mean arterial blood pressure and maximum end-expiratory carbon monoxide in healthy hubble-bubble smokers.

  18. Effects of the positive end-expiratory pressure increase on sublingual microcirculation in patients with acute respiratory distress syndrome

    Directory of Open Access Journals (Sweden)

    Nathaly Fonseca Nunes

    Full Text Available Abstract Objective: The aim of this study was to evaluate the impact of increased positive end-expiratory pressure on the sublingual microcirculation. Methods: Adult patients who were sedated, under mechanical ventilation, and had a diagnosis of circulatory shock and acute respiratory distress syndrome were included. The positive end-expiratory pressure level was settled to obtain a plateau pressure of 30 cm H2O and then maintained at this level for 20 minutes. Microcirculatory (obtained by videomicroscopy and hemodynamic variables were collected at baseline and compared with those at the end of 20 min. Results: Twelve patients were enrolled. Overall, the microcirculation parameters did not significantly change after increasing the positive end-expiratory pressure. However, there was considerable interindividual variability. There was a negative, moderate correlation between the changes in the De Backer score (r = -0.58, p = 0.048, total vessel density (r = -0.60, p = 0.039 and baseline values. The changes in total vessel density (r = 0.54, p = 0.07 and perfused vessel density (r = 0.52, p = 0.08 trended toward correlating with the changes in the mean arterial pressure. Conclusion: Overall, the microcirculation parameters did not significantly change after increasing the positive end-expiratory pressure. However, at individual level, such response was heterogeneous. The changes in the microcirculation parameters could be correlated with the baseline values and changes in the mean arterial pressure.

  19. Clinical assessment of auto-positive end-expiratory pressure by diaphragmatic electrical activity during pressure support and neurally adjusted ventilatory assist.

    Science.gov (United States)

    Bellani, Giacomo; Coppadoro, Andrea; Patroniti, Nicolò; Turella, Marta; Arrigoni Marocco, Stefano; Grasselli, Giacomo; Mauri, Tommaso; Pesenti, Antonio

    2014-09-01

    Auto-positive end-expiratory pressure (auto-PEEP) may substantially increase the inspiratory effort during assisted mechanical ventilation. Purpose of this study was to assess whether the electrical activity of the diaphragm (EAdi) signal can be reliably used to estimate auto-PEEP in patients undergoing pressure support ventilation and neurally adjusted ventilatory assist (NAVA) and whether NAVA was beneficial in comparison with pressure support ventilation in patients affected by auto-PEEP. In 10 patients with a clinical suspicion of auto-PEEP, the authors simultaneously recorded EAdi, airway, esophageal pressure, and flow during pressure support and NAVA, whereas external PEEP was increased from 2 to 14 cm H2O. Tracings were analyzed to measure apparent "dynamic" auto-PEEP (decrease in esophageal pressure to generate inspiratory flow), auto-EAdi (EAdi value at the onset of inspiratory flow), and IDEAdi (inspiratory delay between the onset of EAdi and the inspiratory flow). The pressure necessary to overcome auto-PEEP, auto-EAdi, and IDEAdi was significantly lower in NAVA as compared with pressure support ventilation, decreased with increase in external PEEP, although the effect of external PEEP was less pronounced in NAVA. Both auto-EAdi and IDEAdi were tightly correlated with auto-PEEP (r = 0.94 and r = 0.75, respectively). In the presence of auto-PEEP at lower external PEEP levels, NAVA was characterized by a characteristic shape of the airway pressure. In patients with auto-PEEP, NAVA, compared with pressure support ventilation, led to a decrease in the pressure necessary to overcome auto-PEEP, which could be reliably monitored by the electrical activity of the diaphragm before inspiratory flow onset (auto-EAdi).

  20. Dangerous Pressurization and Inappropriate Alarms during Water Occlusion of the Expiratory Circuit of Commonly Used Infant Ventilators.

    Directory of Open Access Journals (Sweden)

    Murray Hinder

    Full Text Available Non-invasive continuous positive airways pressure is commonly a primary respiratory therapy delivered via multi-purpose ventilators in premature newborns. Expiratory limb occlusion due to water accumulation or 'rainout' from gas humidification is a frequent issue. A case of expiratory limb occlusion due to rainout causing unexpected and excessive repetitive airway pressurisation in a Draeger VN500 prompted a systematic bench test examination of currently available ventilators.To assess neonatal ventilator response to partial or complete expiratory limb occlusion when set to non-invasive continuous positive airway pressure mode.Seven commercially available neonatal ventilators connected to a test lung using a standard infant humidifier circuit with partial and/or complete expiratory limb occlusion were examined in a bench test study. Each ventilator was set to deliver 6 cmH2O in non-invasive mode and respiratory mechanics data for 75%, 80% and 100% occlusion were collected.Several ventilators responded inappropriately with complete occlusion by cyclical pressurisation/depressurisation to peak pressures of between 19·4 and 64·6 cm H2O at rates varying between 2 to 77 inflations per minute. Tidal volumes varied between 10·1 and 24·3mL. Alarm responses varied from 'specific' (tube occluded to 'ambiguous' (Safety valve open. Carefusion Avea responded by continuing to provide the set distending pressure and displaying an appropriate alarm message. Draeger Babylog 8000 did not alarm with partial occlusions and incorrectly displayed airways pressure at 6·1cmH2O compared to the measured values of 13cmH2O.This study found a potential for significant adverse ventilator response due to complete or near complete expiratory limb occlusion in CPAP mode.

  1. Positive end expiratory pressure for preterm infants requiring conventional mechanical ventilation for respiratory distress syndrome or bronchopulmonary dysplasia.

    Science.gov (United States)

    Bamat, Nicolas; Millar, David; Suh, Sanghee; Kirpalani, Haresh

    2012-01-18

    Conventional mechanical ventilation (CMV) of neonates has been used as a treatment of respiratory failure for over 30 years. While CMV facilitates gas exchange, it may simultaneously damage the lung. Positive end expiratory pressure (PEEP) has received less attention than other ventilation parameters when considering this balance of benefit and possible harm. While an appropriate level of PEEP may exert substantial benefits in ventilation, both inappropriately low or high levels may lead to harm. An appropriate level of PEEP for neonates may also be best achieved by an individualized approach. 1. To compare the effects of different levels of PEEP in preterm newborn infants requiring CMV for respiratory distress syndrome (RDS).2. To compare the effects of different levels of PEEP in preterm infants requiring CMV for bronchopulmonary dysplasia (BPD).3. To compare the effects of different methods for individualizing PEEP to an optimal level in preterm newborn infants requiring CMV for RDS. The search was performed in accordance with the standard search strategy for the Cochrane Neonatal Review Group. The Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library), Ovid MEDLINE, EMBASE, study references and experts were utilized for study identification. All randomized and quasi-randomized controlled trials studying preterm infants (less than 37 weeks gestational age) requiring CMV with endotracheal intubation and undergoing randomization to either different PEEP levels (RDS or BPD) or two or more alternative methods for individualizing PEEP levels (RDS only) were included. Cross-over trials were included but we limited the findings to those in the first cross-over period. Data collection and analysis were performed in accordance with the recommendations of the Cochrane Neonatal Review Group. An initial evaluation identified 10 eligible articles. Ultimately, a single study met our inclusion criteria. The study addressed the effects of different

  2. Determination of respiratory system mechanics during inspiration and expiration by FLow-controlled EXpiration (FLEX): a pilot study in anesthetized pigs.

    Science.gov (United States)

    Schumann, S; Goebel, U; Haberstroh, J; Vimlati, L; Schneider, M; Lichtwarck-Aschoff, M; Guttmann, J

    2014-01-01

    Differences between inspiratory and expiratory lung mechanics result in the hysteresis of the pressure volume-loop. While hysteresis area is a global parameter describing the difference between inspiration and expiration in mechanics under quasi-static conditions, a detailed analysis of this difference under the dynamic conditions of mechanical ventilation is feasible once inspiratory and expiratory compliance (Cin/Cex) are determined separately. This requires uncoupling of expiratory flow rate and volume (V). Five piglets were mechanically ventilated at positive end-expiratory pressure (PEEP) levels ranging from 0 to 15 cmH2O. Expiratory flow rate was linearized by a computer-controlled resistor (flow-controlled expiration). The volume-dependent Cin(V) and Cex(V) profiles were calculated from the tracheal pressure volume-loops. The intratidal curve-progression of Cex(V) was altogether higher with a steeper slope compared to Cin(V). With increasing positive end-expiratory pressure (PEEP) dynamic hysteresis area decreased and Cex(V) tended to run more parallel to Cin(V). The relation between inspiratory and expiratory compliance profiles is associated with the hysteresis area and behaves PEEP dependent. Analysing the Cin-Cex-relation might therefore potentially offer a new approach to titrate PEEP and tidal volume.

  3. On the Bipolar DC Flow Field-Effect-Transistor for Multifunctional Sample Handing in Microfluidics: A Theoretical Analysis under the Debye–Huckel Limit

    Directory of Open Access Journals (Sweden)

    Weiyu Liu

    2018-02-01

    Full Text Available We present herein a novel method of bipolar field-effect control on DC electroosmosis (DCEO from a physical point of view, in the context of an intelligent and robust operation tool for stratified laminar streams in microscale systems. In this unique design of the DC flow field-effect-transistor (DC-FFET, a pair of face-to-face external gate terminals are imposed with opposite gate-voltage polarities. Diffuse-charge dynamics induces heteropolar Debye screening charge within the diffuse double layer adjacent to the face-to-face oppositely-polarized gates, respectively. A background electric field is applied across the source-drain terminal and forces the face-to-face counterionic charge of reversed polarities into induced-charge electroosmotic (ICEO vortex flow in the lateral direction. The chaotic turbulence of the transverse ICEO whirlpool interacts actively with the conventional plug flow of DCEO, giving rise to twisted streamlines for simultaneous DCEO pumping and ICEO mixing of fluid samples along the channel length direction. A mathematical model in thin-layer approximation and the low-voltage limit is subsequently established to test the feasibility of the bipolar DC-FFET configuration in electrokinetic manipulation of fluids at the micrometer dimension. According to our simulation analysis, an integrated device design with two sets of side-by-side, but upside-down gate electrode pair exhibits outstanding performance in electroconvective pumping and mixing even without any externally-applied pressure difference. Moreover, a paradigm of a microdevice for fully electrokinetics-driven analyte treatment is established with an array of reversed bipolar gate-terminal pairs arranged on top of the dielectric membrane along the channel length direction, from which we can obtain almost a perfect liquid mixture by using a smaller magnitude of gate voltages for causing less detrimental effects at a small Dukhin number. Sustained by theoretical

  4. Influence of the respiratory flow pattern on rebreathing in Mapleson A and D circuits.

    Science.gov (United States)

    Jonsson, L O; Zetterström, H

    1987-02-01

    In a lung model the rebreathing effects of different respiratory flow patterns (RFP) were studied in the coaxial Mapleson A (Lack) and D (Bain, Coax-II) systems during spontaneous breathing. In the Mapleson A system RFP was not found to have any impact. In the D systems FACO2 was higher with an RFP typical of halothane-anaesthetized patients than with an RFP with an exponentially decreasing expiratory flow and an end-expiratory flow pause (FTEP). The difference in FACO2 was 26% with a VF corresponding to 100 ml X min-1 X kg-1 body weight. The RFP in a non-anaesthetized volunteer was intermediate between these two patterns. Rebreathing decreased in the D systems with prolongation of FTEP and when a decelerating expiratory flow was used.

  5. A Comprehensive Breath Plume Model for Disease Transmission via Expiratory Aerosols

    Science.gov (United States)

    Halloran, S. K.; Wexler, A. S.; Ristenpart, W. D.

    2012-11-01

    The peak in influenza incidence during wintertime represents a longstanding unresolved scientific question. One hypothesis is that the efficacy of airborne transmission via aerosols is increased at low humidity and temperature, conditions that prevail in wintertime. Recent experiments with guinea pigs suggest that transmission is indeed maximized at low humidity and temperature, a finding which has been widely interpreted in terms of airborne influenza virus survivability. This interpretation, however, neglects the effect of the airflow on the transmission probability. Here we provide a comprehensive model for assessing the probability of disease transmission via expiratory aerosols between test animals in laboratory conditions. The spread of aerosols emitted from an infected animal is modeled using dispersion theory for a homogeneous turbulent airflow. The concentration and size distribution of the evaporating droplets in the resulting ``Gaussian breath plume'' are calculated as functions of downstream position. We demonstrate that the breath plume model is broadly consistent with the guinea pig experiments, without invoking airborne virus survivability. Moreover, the results highlight the need for careful characterization of the airflow in airborne transmission experiments.

  6. Volume-monitored chest CT: a simplified method for obtaining motion-free images near full inspiratory and end expiratory lung volumes

    Energy Technology Data Exchange (ETDEWEB)

    Mueller, Kathryn S. [The Ohio State University College of Medicine, Columbus, OH (United States); Long, Frederick R. [Nationwide Children' s Hospital, The Children' s Radiological Institute, Columbus, OH (United States); Flucke, Robert L. [Nationwide Children' s Hospital, Department of Pulmonary Medicine, Columbus, OH (United States); Castile, Robert G. [The Research Institute at Nationwide Children' s Hospital, Center for Perinatal Research, Columbus, OH (United States)

    2010-10-15

    Lung inflation and respiratory motion during chest CT affect diagnostic accuracy and reproducibility. To describe a simple volume-monitored (VM) method for performing reproducible, motion-free full inspiratory and end expiratory chest CT examinations in children. Fifty-two children with cystic fibrosis (mean age 8.8 {+-} 2.2 years) underwent pulmonary function tests and inspiratory and expiratory VM-CT scans (1.25-mm slices, 80-120 kVp, 16-40 mAs) according to an IRB-approved protocol. The VM-CT technique utilizes instruction from a respiratory therapist, a portable spirometer and real-time documentation of lung volume on a computer. CT image quality was evaluated for achievement of targeted lung-volume levels and for respiratory motion. Children achieved 95% of vital capacity during full inspiratory imaging. For end expiratory scans, 92% were at or below the child's end expiratory level. Two expiratory exams were judged to be at suboptimal volumes. Two inspiratory (4%) and three expiratory (6%) exams showed respiratory motion. Overall, 94% of scans were performed at optimal volumes without respiratory motion. The VM-CT technique is a simple, feasible method in children as young as 4 years to achieve reproducible high-quality full inspiratory and end expiratory lung CT images. (orig.)

  7. Current limiters

    Energy Technology Data Exchange (ETDEWEB)

    Loescher, D.H. [Sandia National Labs., Albuquerque, NM (United States). Systems Surety Assessment Dept.; Noren, K. [Univ. of Idaho, Moscow, ID (United States). Dept. of Electrical Engineering

    1996-09-01

    The current that flows between the electrical test equipment and the nuclear explosive must be limited to safe levels during electrical tests conducted on nuclear explosives at the DOE Pantex facility. The safest way to limit the current is to use batteries that can provide only acceptably low current into a short circuit; unfortunately this is not always possible. When it is not possible, current limiters, along with other design features, are used to limit the current. Three types of current limiters, the fuse blower, the resistor limiter, and the MOSFET-pass-transistor limiters, are used extensively in Pantex test equipment. Detailed failure mode and effects analyses were conducted on these limiters. Two other types of limiters were also analyzed. It was found that there is no best type of limiter that should be used in all applications. The fuse blower has advantages when many circuits must be monitored, a low insertion voltage drop is important, and size and weight must be kept low. However, this limiter has many failure modes that can lead to the loss of over current protection. The resistor limiter is simple and inexpensive, but is normally usable only on circuits for which the nominal current is less than a few tens of milliamperes. The MOSFET limiter can be used on high current circuits, but it has a number of single point failure modes that can lead to a loss of protective action. Because bad component placement or poor wire routing can defeat any limiter, placement and routing must be designed carefully and documented thoroughly.

  8. Peak expiratory flow rate in asymptomatic male workers exposed to chemical fumes, in various industries of Hyderabad

    Directory of Open Access Journals (Sweden)

    Padaki Samata K, Dambal Amrut , Kokiwar Prashant

    2014-11-01

    Full Text Available Context: The prevalence of occupational health hazards and mortality has been reported to be unusually high among people of India. Although developed countries are very much careful about the health in occupations it is quite neglected in the developing countries like India. Aims: To record PEFR in asymptomatic male workers exposed to chemical fumes for more than 2 years and compare the results with age matched unexposed, healthy male controls. Methods and Material: This was a comparative study between 50 asymptomatic male workers exposed to chemical fumes for more than 2 years in various industries located at Jeedimetla Industrial Area and 50 unexposed healthy male individuals from general population. The sampling was done by simple random sampling (lottery method. The data was collected in the Research Laboratory of Physiology. Anthropometry like weight, height, was measured and the PEFR test was performed in the standing position by taking a deep inspiration and then blowing out as hard and as quickly as possible with their nose closed. Data was analyzed by using SPSS package and was expressed in terms of mean ± SD. Results: It was observed that mean PEFR was statistically highly significant in cases (p = 0.0001, and PEFR decreased with increase in duration of exposure. Conclusions: Thus, it can be concluded that apparently healthy individuals may also have abnormal PEFR findings. Hence, a regular check on these parameters will help them in reducing the chances of its manifestation at a future date.

  9. Cystic Fibrosis: Are Volumetric Ultra-Low-Dose Expiratory CT Scans Sufficient for Monitoring Related Lung Disease?

    DEFF Research Database (Denmark)

    Loeve, Martine; Lequin, Maarten H; Bruijne, Marleen de

    2009-01-01

    with CF aged 6–20 years (eight males, 12 females) underwent low-dose end-inspiratory CT and ultra-low-dose end-expiratory CT. Informed consent was obtained. Scans were randomized and scored by using the Brody-II CT scoring system to assess bronchiectasis, airway wall thickening, mucus plugging......-inspiratory and end-expiratory CT scores for Brody-II total score (ICC = 0.96), bronchiectasis (ICC = 0.98), airway wall thickening (ICC = 0.94), mucus plugging (ICC = 0.96), and opacities (ICC = 0.90). Intra- and interobserver agreement were good to very good (ICC range, 0.70–0.98). Bland-Altman plots showed...

  10. Influence of ion effects on a space charge limited field emission flow: from non-relativistic to ultra-relativistic regimes

    Science.gov (United States)

    Lin, M. C.; Chang, P. C.; Lu, P. S.; Verboncoeur, J. P.

    2011-10-01

    Influence of ion effects on a space charge limited field emission flow has been studied systematically, by employing both analytical and numerical approaches. In our model, the field emission of electrons is described by the Fowler-Nordheim equation. The cathode plasma and surface properties are considered within the framework of an effective work function approximation. Ionization effects at the anode as well as electron space-charge effects are described by Poisson's equation coupled with the energy conservation equation including the relativistic effects. The calculations are carried out self-consistently to yield the steady states of the bipolar flow. The electric field on the cathode surface is found to be saturated due to space charge effects and is determined by the effective work function approximately. In addition, the upstream ion current bas been treated as a tuning parameter. It is found that the field emission currents in the presence of saturated ion currents can be enhanced to be nearly 1.8, 1.5, and 1.4 times of the cases with no upstream ion current in non-relativistic, intermediate, and ultra-relativistic regimes, respectively. The solutions have also been verified using 1D PIC simulations, as implemented in the OOPD1 code developed by PTSG of UC Berkeley. Work supported by the National Science Council, Taiwan, R.O.C. under Grant No. NSC 96-2112-M-030-004-MY3, National Center for Theoretical Sciences, and National Center for High-Performance Computing, Taiwan, ROC which provides the computing resources.

  11. An experimental study on the impacts of inspiratory and expiratory muscles activities during mechanical ventilation in ARDS animal model

    OpenAIRE

    Xianming Zhang; Juan Du; Weiliang Wu; Yongcheng Zhu; Ying Jiang; Rongchang Chen

    2017-01-01

    In spite of intensive investigations, the role of spontaneous breathing (SB) activity in ARDS has not been well defined yet and little has been known about the different contribution of inspiratory or expiratory muscles activities during mechanical ventilation in patients with ARDS. In present study, oleic acid-induced beagle dogs? ARDS models were employed and ventilated with the same level of mean airway pressure. Respiratory mechanics, lung volume, gas exchange and inflammatory cytokines w...

  12. Effects of positive end-expiratory pressure and recruitment maneuvers in a ventilator-induced injury mouse model.

    Science.gov (United States)

    Cagle, Laura A; Franzi, Lisa M; Linderholm, Angela L; Last, Jerold A; Adams, Jason Y; Harper, Richart W; Kenyon, Nicholas J

    2017-01-01

    Positive-pressure mechanical ventilation is an essential therapeutic intervention, yet it causes the clinical syndrome known as ventilator-induced lung injury. Various lung protective mechanical ventilation strategies have attempted to reduce or prevent ventilator-induced lung injury but few modalities have proven effective. A model that isolates the contribution of mechanical ventilation on the development of acute lung injury is needed to better understand biologic mechanisms that lead to ventilator-induced lung injury. To evaluate the effects of positive end-expiratory pressure and recruitment maneuvers in reducing lung injury in a ventilator-induced lung injury murine model in short- and longer-term ventilation. 5-12 week-old female BALB/c mice (n = 85) were anesthetized, placed on mechanical ventilation for either 2 hrs or 4 hrs with either low tidal volume (8 ml/kg) or high tidal volume (15 ml/kg) with or without positive end-expiratory pressure and recruitment maneuvers. Alteration of the alveolar-capillary barrier was noted at 2 hrs of high tidal volume ventilation. Standardized histology scores, influx of bronchoalveolar lavage albumin, proinflammatory cytokines, and absolute neutrophils were significantly higher in the high-tidal volume ventilation group at 4 hours of ventilation. Application of positive end-expiratory pressure resulted in significantly decreased standardized histology scores and bronchoalveolar absolute neutrophil counts at low- and high-tidal volume ventilation, respectively. Recruitment maneuvers were essential to maintain pulmonary compliance at both 2 and 4 hrs of ventilation. Signs of ventilator-induced lung injury are evident soon after high tidal volume ventilation (as early as 2 hours) and lung injury worsens with longer-term ventilation (4 hrs). Application of positive end-expiratory pressure and recruitment maneuvers are protective against worsening VILI across all time points. Dynamic compliance can be used guide the frequency

  13. Effects of positive end-expiratory pressure and recruitment maneuvers in a ventilator-induced injury mouse model.

    Directory of Open Access Journals (Sweden)

    Laura A Cagle

    Full Text Available Positive-pressure mechanical ventilation is an essential therapeutic intervention, yet it causes the clinical syndrome known as ventilator-induced lung injury. Various lung protective mechanical ventilation strategies have attempted to reduce or prevent ventilator-induced lung injury but few modalities have proven effective. A model that isolates the contribution of mechanical ventilation on the development of acute lung injury is needed to better understand biologic mechanisms that lead to ventilator-induced lung injury.To evaluate the effects of positive end-expiratory pressure and recruitment maneuvers in reducing lung injury in a ventilator-induced lung injury murine model in short- and longer-term ventilation.5-12 week-old female BALB/c mice (n = 85 were anesthetized, placed on mechanical ventilation for either 2 hrs or 4 hrs with either low tidal volume (8 ml/kg or high tidal volume (15 ml/kg with or without positive end-expiratory pressure and recruitment maneuvers.Alteration of the alveolar-capillary barrier was noted at 2 hrs of high tidal volume ventilation. Standardized histology scores, influx of bronchoalveolar lavage albumin, proinflammatory cytokines, and absolute neutrophils were significantly higher in the high-tidal volume ventilation group at 4 hours of ventilation. Application of positive end-expiratory pressure resulted in significantly decreased standardized histology scores and bronchoalveolar absolute neutrophil counts at low- and high-tidal volume ventilation, respectively. Recruitment maneuvers were essential to maintain pulmonary compliance at both 2 and 4 hrs of ventilation.Signs of ventilator-induced lung injury are evident soon after high tidal volume ventilation (as early as 2 hours and lung injury worsens with longer-term ventilation (4 hrs. Application of positive end-expiratory pressure and recruitment maneuvers are protective against worsening VILI across all time points. Dynamic compliance can be used guide

  14. Unintentional variation in positive end expiratory pressure during resuscitation with a T-piece resuscitator.

    Science.gov (United States)

    Finer, Neil N; Rich, Wade D

    2011-06-01

    The ability of T-piece resuscitators to deliver consistent peak inspiratory pressure (PIP) and positive end expiratory pressure (PEEP) during real and simulated neonatal resuscitation has been well described. The Neopuff (Fisher & Paykel Healthcare, Auckland, New Zealand) has been the device used for nearly all of these comparisons. All high risk resuscitations were carried out in our dedicated resuscitation room, and were recorded on video tape for quality assurance purposes.(1) In addition to the audio and video recording, physiologic signals and resuscitation parameters, including oxygen saturation, pulse rate, airway pressure, FiO(2), and others signals as appropriate were also captured. These recordings were reviewed on a biweekly basis as part of a continuing quality review process. Resuscitations were graded for standard of care and the resuscitation checklist was reviewed to determine if the team had any unresolved issues that needed to be addressed. In the year between April of 2009 and March 2010, a period when we fully reviewed approximately 120 videos, we recognized visually obvious PEEP changes on 8 different occasions in ELBW infants. Our target PEEP was 5 cm H20. We observed rapid changes in the PEEP to as high as 15 cm H20 during resuscitation. Based on our single-center experience, a T-piece resuscitation device which has the adjustment for the PEEP level and the orifice which is occluded to deliver a breath in the same location has the potential to cause an inadvertent and potentially toxic increase of PEEP which might not be noticed by the operator. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

  15. Positive end-expiratory pressure improves gas exchange and pulmonary mechanics during partial liquid ventilation.

    Science.gov (United States)

    Kirmse, M; Fujino, Y; Hess, D; Kacmarek, R M

    1998-11-01

    Partial liquid ventilation (PLV) with perflubron (PFB) has been proposed as an adjunct to the current therapies for the acute respiratory distress syndrome (ARDS). Because PFB has been also referred to as "liquid PEEP," distributing to the most gravity-dependent regions of the lung, less attention has been paid to the amount of applied positive end-expiratory pressure (PEEP). We hypothesized that higher PEEP levels than currently applied are needed to optimize gas exchange, and that the lower inflection point (LIP) of the pressure-volume curve could be used to estimate the amount of PEEP needed when the lung is filled with PFB. Lung injury was induced in 23 sheep by repeated lung lavage with warmed saline until the PaO2/FIO2 ratio fell below 150. Five sheep were used to investigate the change of the LIP when the lung was filled with PFB in increments of 5 ml/kg/body weight to a total of 30 ml/kg/body weight. To evaluate the impact of PEEP set at LIP +1 cm H2O we randomized an additional 15 sheep to three groups with different doses (7.5 ml, 15 ml, 30 ml/kg/body weight) of PFB. In random order a PEEP of 5 cm H2O or PEEP at LIP +1 cm H2O was applied. The LIP decreased with incremental filling of PFB to a minimum at 10 ml (p PFB shifts the LIP to the left, and that setting PEEP at LIP +1 cm H2O improves gas exchange at moderate to high doses of PFB.

  16. Pulmonary acute respiratory distress syndrome: positive end-expiratory pressure titration needs stress index.

    Science.gov (United States)

    Huang, Yingzi; Yang, Yi; Chen, Qiuhua; Liu, Songqiao; Liu, Ling; Pan, Chun; Yang, Congshan; Qiu, Haibo

    2013-11-01

    The heterogeneity of lung injury in pulmonary acute respiratory distress syndrome (ARDS) may have contributed to the greater response of hyperinflated area with positive end-expiratory pressure (PEEP). PEEP titrated by stress index can reduce the risk of alveolar hyperinflation in patients with pulmonary ARDS. The authors sought to investigate the effects of PEEP titrated by stress index on lung recruitment and protection after recruitment maneuver (RM) in pulmonary ARDS patients. Thirty patients with pulmonary ARDS were enrolled. After RM, PEEP was randomly set according to stress index, oxygenation, static pulmonary compliance (Cst), or lower inflection point (LIP) + 2 cmH2O strategies. Recruitment volume, gas exchange, respiratory mechanics, and hemodynamic parameters were collected. PEEP titrated by stress index (15.1 ± 1.8 cmH2O) was similar to the levels titrated by oxygenation (14.5 ± 2.9 cmH2O), higher than that titrated by Cst (11.3 ± 2.5 cmH2O) and LIP (12.9 ± 1.6 cmH2O) (P stress index and oxygenation but higher than that titrated by Cst and LIP. Compared with baseline, lung compliance increased significantly when PEEP determined by Cst, but there was no difference of Cst in these four strategies. There was no influence of PEEP titration with the four strategies on hemodynamic parameters. PEEP titration by stress index might be more beneficial for pulmonary ARDS patients after RM. Copyright © 2013 Elsevier Inc. All rights reserved.

  17. The Effect of Positive End-Expiratory Pressure on Intracranial Pressure and Cerebral Hemodynamics.

    Science.gov (United States)

    Boone, Myles D; Jinadasa, Sayuri P; Mueller, Ariel; Shaefi, Shahzad; Kasper, Ekkehard M; Hanafy, Khalid A; O'Gara, Brian P; Talmor, Daniel S

    2017-04-01

    Lung protective ventilation has not been evaluated in patients with brain injury. It is unclear whether applying positive end-expiratory pressure (PEEP) adversely affects intracranial pressure (ICP) and cerebral perfusion pressure (CPP). We aimed to evaluate the effect of PEEP on ICP and CPP in a large population of patients with acute brain injury and varying categories of acute lung injury, defined by PaO 2 /FiO 2 . Retrospective data were collected from 341 patients with severe acute brain injury admitted to the ICU between 2008 and 2015. These patients experienced a total of 28,644 paired PEEP and ICP observations. Demographic, hemodynamic, physiologic, and ventilator data at the time of the paired PEEP and ICP observations were recorded. In the adjusted analysis, a statistically significant relationship between PEEP and ICP and PEEP and CPP was found only among observations occurring during periods of severe lung injury. For every centimeter H 2 O increase in PEEP, there was a 0.31 mmHg increase in ICP (p = 0.04; 95 % CI [0.07, 0.54]) and a 0.85 mmHg decrease in CPP (p = 0.02; 95 % CI [-1.48, -0.22]). Our results suggest that PEEP can be applied safely in patients with acute brain injury as it does not have a clinically significant effect on ICP or CPP. Further prospective studies are required to assess the safety of applying a lung protective ventilation strategy in brain-injured patients with lung injury.

  18. A comprehensive breath plume model for disease transmission via expiratory aerosols.

    Directory of Open Access Journals (Sweden)

    Siobhan K Halloran

    Full Text Available The peak in influenza incidence during wintertime in temperate regions represents a longstanding, unresolved scientific question. One hypothesis is that the efficacy of airborne transmission via aerosols is increased at lower humidities and temperatures, conditions that prevail in wintertime. Recent work with a guinea pig model by Lowen et al. indicated that humidity and temperature do modulate airborne influenza virus transmission, and several investigators have interpreted the observed humidity dependence in terms of airborne virus survivability. This interpretation, however, neglects two key observations: the effect of ambient temperature on the viral growth kinetics within the animals, and the strong influence of the background airflow on transmission. Here we provide a comprehensive theoretical framework for assessing the probability of disease transmission via expiratory aerosols between test animals in laboratory conditions. The spread of aerosols emitted from an infected animal is modeled using dispersion theory for a homogeneous turbulent airflow. The concentration and size distribution of the evaporating droplets in the resulting "Gaussian breath plume" are calculated as functions of position, humidity, and temperature. The overall transmission probability is modeled with a combination of the time-dependent viral concentration in the infected animal and the probability of droplet inhalation by the exposed animal downstream. We demonstrate that the breath plume model is broadly consistent with the results of Lowen et al., without invoking airborne virus survivability. The results also suggest that, at least for guinea pigs, variation in viral kinetics within the infected animals is the dominant factor explaining the increased transmission probability observed at lower temperatures.

  19. The stationary flow in a heterogeneous compliant vessel network

    International Nuclear Information System (INIS)

    Filoche, Marcel; Florens, Magali

    2011-01-01

    We introduce a mathematical model of the hydrodynamic transport into systems consisting in a network of connected flexible pipes. In each pipe of the network, the flow is assumed to be steady and one-dimensional. The fluid-structure interaction is described through tube laws which relate the pipe diameter to the pressure difference across the pipe wall. We show that the resulting one-dimensional differential equation describing the flow in the pipe can be exactly integrated if one is able to estimate averages of the Reynolds number along the pipe. The differential equation is then transformed into a non linear scalar equation relating pressures at both ends of the pipe and the flow rate in the pipe. These equations are coupled throughout the network with mass conservation equations for the flow and zero pressure losses at the branching points of the network. This allows us to derive a general model for the computation of the flow into very large inhomogeneous networks consisting of several thousands of flexible pipes. This model is then applied to perform numerical simulations of the human lung airway system at exhalation. The topology of the system and the tube laws are taken from morphometric and physiological data in the literature. We find good qualitative and quantitative agreement between the simulation results and flow-volume loops measured in real patients. In particular, expiratory flow limitation which is an essential characteristic of forced expiration is found to be well reproduced by our simulations. Finally, a mathematical model of a pathology (Chronic Obstructive Pulmonary Disease) is introduced which allows us to quantitatively assess the influence of a moderate or severe alteration of the airway compliances.

  20. The stationary flow in a heterogeneous compliant vessel network

    Energy Technology Data Exchange (ETDEWEB)

    Filoche, Marcel [Physique de la Matiere Condensee, Ecole Polytechnique, CNRS, 91228 Palaiseau (France); Florens, Magali [CMLA, ENS Cachan, CNRS, UniverSud, 61 av. du President Wilson, Cachan (France)

    2011-09-15

    We introduce a mathematical model of the hydrodynamic transport into systems consisting in a network of connected flexible pipes. In each pipe of the network, the flow is assumed to be steady and one-dimensional. The fluid-structure interaction is described through tube laws which relate the pipe diameter to the pressure difference across the pipe wall. We show that the resulting one-dimensional differential equation describing the flow in the pipe can be exactly integrated if one is able to estimate averages of the Reynolds number along the pipe. The differential equation is then transformed into a non linear scalar equation relating pressures at both ends of the pipe and the flow rate in the pipe. These equations are coupled throughout the network with mass conservation equations for the flow and zero pressure losses at the branching points of the network. This allows us to derive a general model for the computation of the flow into very large inhomogeneous networks consisting of several thousands of flexible pipes. This model is then applied to perform numerical simulations of the human lung airway system at exhalation. The topology of the system and the tube laws are taken from morphometric and physiological data in the literature. We find good qualitative and quantitative agreement between the simulation results and flow-volume loops measured in real patients. In particular, expiratory flow limitation which is an essential characteristic of forced expiration is found to be well reproduced by our simulations. Finally, a mathematical model of a pathology (Chronic Obstructive Pulmonary Disease) is introduced which allows us to quantitatively assess the influence of a moderate or severe alteration of the airway compliances.

  1. Protective intraoperative ventilation with higher versus lower levels of positive end-expiratory pressure in obese patients (PROBESE): study protocol for a randomized controlled trial

    NARCIS (Netherlands)

    Bluth, T.; Teichmann, R.; Kiss, T.; Bobek, I.; Canet, J.; Cinnella, G.; de Baerdemaeker, L.; Gregoretti, C.; Hedenstierna, G.; Hemmes, S. N.; Hiesmayr, M.; Hollmann, M. W.; Jaber, S.; Laffey, J. G.; Licker, M. J.; Markstaller, K.; Matot, I.; Müller, G.; Mills, G. H.; Mulier, J. P.; Putensen, C.; Rossaint, R.; Schmitt, J.; Senturk, M.; Serpa Neto, A.; Severgnini, P.; Sprung, J.; Vidal Melo, M. F.; Wrigge, H.; Schultz, M. J.; Pelosi, P.; Gama de Abreu, M.; Güldner, Andreas; Huhle, Robert; Uhlig, Christopher; Vivona, Luigi; Bergamaschi, Alice; Rossaint, Rolf; Stevanovic, Ana; Treschan, Tanja; Schaefer, Maximilian; Kienbaum, Peter; Laufenberg-Feldmann, Rita; Bergmann, Lars; Ebner, Felix; Robitzky, Luisa; Mölders, Patrick; Unterberg, Matthias; Busch, Cornelius; Achilles, Marc; Menzen, Angelika; Freesemann, Harbert; Putensen, Christian; Machado, Humberto; Cavaleiro, Carla; Ferreira, Cristina; Pinho, Daniela; Carvalho, Marta; Pinho, Sílvia; Soares, Maria; Castro, Diogo Sousa; Abelha, Fernando; Rabico, Rui; Delphin, Ellise; Sprung, Juraj; Weingarten, Toby N.; Kellogg, Todd A.; Martin, Yvette N.; McKenzie, Travis J.; Brull, Sorin J.; Renew, J. Ross; Ramakrishna, Harish; Fernandez-Bustamante, Ana; Balonov, Konstantin; Baig, Harris R.; Kacha, Aalok; Pedemonte, Juan C.; Altermatt, Fernando; Corvetto, Marcia A.; Paredes, Sebastian; Carmona, Javiera; Rolle, Augusto; Bos, Elke; Beurskens, Charlotte; Veering, B.; Zonneveldt, Harry; Boer, Christa; Godfried, Marc; Thiel, Bram; Kabon, Barbara; Reiterer, Christian; Canet, Jaume; Tolós, Raquel; Sendra, Mar; González, Miriam; Gómez, Noemí; Ferrando, Carlos; Socorro, Tania; Izquierdo, Ana; Soro, Marina; Granell Gil, Manuel; Hernández Cádiz, María José; Biosca Pérez, Elena; Suarez-de-la-Rica, Alejandro; Lopez-Martinez, Mercedes; Huercio, Iván; Maseda, Emilio; Yagüe, Julio; Cebrian Moreno, Alba; Rivas, Eva; Lopez-Baamonde, Manuel; Elgendy, Hamed; Sayedalahl, Mohamed; SIibai, Abdul Razak; Yavru, Aysen; Sivrikoz, Nukhet; Karadeniz, Meltem; Corman Dincer, Pelin; Ayanoglu, Hilmi Omer; Tore Altun, Gulbin; Kavas, Ayse Duygu; Dinc, Bora; Kuvaki, Bahar; Ozbilgin, Sule; Erdogan, Dilek; Koksal, Ceren; Abitagaglu, Suheyla; Aurilio, Caterina; Sansone, Pasquale; Pace, Caterina Maria; Donatiello, Valerio; Mattera, Silvana; Nazareno, Palange; Di Colandrea, Salvatore; Spadaro, Savino; Volta, Carlo Alberto; Ragazzi, Riccardo; Ciardo, Stefano; Gobbi, Luca; Severgnini, Paolo; Bacuzzi, Alessandro; Brugnoni, Elisa; Gratarola, Angelo; Micalizzi, Camilla; Simonassi, Francesca; Malerbi, Patrizia; Carboni, Adrea; Licker, Marc-Joseph; Dullenkopf, Alexander; Goettel, Nicolai; Nesek Adam, Visnja; Karaman Ilić, Maja; Klaric, Vlasta; Vitkovic, Bibiana; Milic, Morena; Miro, Zupcic; de Baerdemaeker, Luc; de Hert, Stefan; Heyse, Bjorn; van Limmen, Jurgen; van Nieuwenhove, Yves; Mertens, Els; Neyrinck, Arne; Mulier, Jan; Kahn, David; Godoroja, Daniela; Martin-Loeches, Martin; Vorotyntsev, Sergiy; Fronchko, Valentyna; Matot, Idit; Goren, Or; Zac, Lilach; Gaszynski, Thomasz; Laffey, Jon; Mills, Gary; Nalwaya, Pramod; Mac Gregor, Mark; Paddle, Jonathan; Balaji, Packianathaswamy; Rubulotta, Francesca; Adebesin, Afeez; Margarson, Mike; Davies, Simon; Rangarajan, Desikan; Newell, Christopher; Shosholcheva, Mirjana; Papaspyros, Fotios; Skandalou, Vasiliki; Dzurňáková, Paula

    2017-01-01

    Background: Postoperative pulmonary complications (PPCs) increase the morbidity and mortality of surgery in obese patients. High levels of positive end-expiratory pressure (PEEP) with lung recruitment maneuvers may improve intraoperative respiratory function, but they can also compromise

  2. Application of the Novel Ventilation Mode FLow-Controlled EXpiration (FLEX): A Crossover Proof-of-Principle Study in Lung-Healthy Patients.

    Science.gov (United States)

    Wirth, Steffen; Springer, Sebastian; Spaeth, Johannes; Borgmann, Silke; Goebel, Ulrich; Schumann, Stefan

    2017-10-01

    Traditionally, mechanical ventilation is achieved via active lung inflation during inspiration and passive lung emptying during expiration. By contrast, the novel FLEX (FLow-controlled EXpiration) ventilator mode actively decreases the rate of lung emptying. We investigated whether FLEX can be used during intraoperative mechanical ventilation of lung-healthy patients. In 30 adult patients scheduled for neurosurgical procedures, we studied respiratory system mechanics, regional ventilation, oxygenation, and hemodynamics during ventilation with and without FLEX at positive end-expiratory pressure (PEEP) of 5 and 7 cm H2O. The FLEX system was integrated into the expiratory limb and modified the expiratory flow profile by continuously changing expiratory resistance according to a computer-controlled algorithm. Mean airway pressure increased with PEEP by 1.9 cm H2O and with FLEX by 1 cm H2O (all P ventilated during general anesthesia. FLEX improves the homogeneous distribution of ventilation in the lungs.

  3. Using an aqueous two-phase polymer-salt system to rapidly concentrate viruses for improving the detection limit of the lateral-flow immunoassay.

    Science.gov (United States)

    Jue, Erik; Yamanishi, Cameron D; Chiu, Ricky Y T; Wu, Benjamin M; Kamei, Daniel T

    2014-12-01

    The development of point-of-need (PON) diagnostics for viruses has the potential to prevent pandemics and protects against biological warfare threats. Here we discuss the approach of using aqueous two-phase systems (ATPSs) to concentrate biomolecules prior to the lateral-flow immunoassay (LFA) for improved viral detection. In this paper, we developed a rapid PON detection assay as an extension to our previous proof-of-concept studies which used a micellar ATPS. We present our investigation of a more rapid polymer-salt ATPS that can drastically improve the assay time, and show that the phase containing the concentrated biomolecule can be extracted prior to macroscopic phase separation equilibrium without affecting the measured biomolecule concentration in that phase. We could therefore significantly decrease the time of the diagnostic assay with an early extraction time of just 30 min. Using this rapid ATPS, the model virus bacteriophage M13 was concentrated between approximately 2 and 10-fold by altering the volume ratio between the two phases. As the extracted virus-rich phase contained a high salt concentration which destabilized the colloidal gold indicator used in LFA, we decorated the gold nanoprobes with polyethylene glycol (PEG) to provide steric stabilization, and used these nanoprobes to demonstrate a 10-fold improvement in the LFA detection limit. Lastly, a MATLAB script was used to quantify the LFA results with and without the pre-concentration step. This approach of combining a rapid ATPS with LFA has great potential for PON applications, especially as greater concentration-fold improvements can be achieved by further varying the volume ratio. Biotechnol. Bioeng. 2014;111: 2499-2507. © 2014 Wiley Periodicals, Inc. © 2014 Wiley Periodicals, Inc.

  4. A combined inspiratory and expiratory muscle training program improves respiratory muscle strength and fatigue in multiple sclerosis.

    Science.gov (United States)

    Ray, Andrew D; Udhoji, Supriya; Mashtare, Terry L; Fisher, Nadine M

    2013-10-01

    To determine the effects of a short-duration, combined (inspiratory and expiratory), progressive resistance respiratory muscle training (RMT) protocol on respiratory muscle strength, fatigue, health-related quality of life, and functional performance in individuals with mild-to-moderate multiple sclerosis (MS). Quasi-experimental before-after trial. University rehabilitation research laboratory. Volunteers with MS (N=21) were divided into 2 groups: RMT (n=11; 9 women, 2 men; mean age ± SD, 50.9 ± 5.7y, mean Expanded Disability Status Scale score ± SD, 3.2 ± 1.9) and a control group that did not train (n=10; 7 women, 3 men; mean age ± SD, 56.2 ± 8.8y, mean Expanded Disability Status Scale score ± SD, 4.4 ± 2.1). Expanded Disability Status Scale scores ranged from 1 to ≤6.5. No patients withdrew from the study. Training was a 5-week combined progressive resistance RMT program, 3d/wk, 30 minutes per session. The primary outcome measures were maximal inspiratory pressure and expiratory pressure and the Modified Fatigue Impact Scale. All subjects completed secondary measures of pulmonary function, the six-minute walk test, the timed stair climb, the Multiple Sclerosis Self-Efficacy Scale, the Medical Outcomes Study 36-Item Short-Form Health Survey, and the Physical Activity Disability Scale. Maximal inspiratory pressure and expiratory pressure (mean ± SD) increased 35% ± 22% (Pfatigue (Modified Fatigue Impact Scale, Pmuscle strength and reduced fatigue in patients with mild to moderate MS. Copyright © 2013 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

  5. Paired inspiratory/expiratory spiral CT and continuous respiration cine CT in the diagnosis of tracheal instability

    International Nuclear Information System (INIS)

    Heussel, C.P.; Schreiber, W.; Thelen, M.; Kauczor, H.U.; Hafner, B.; Lill, J.

    2001-01-01

    In tracheo- and bronchomalacia, localisation and determination of collapse is necessary for planning of surgical procedure. We compared inspiratory and expiratory spiral CT, cine CT, bronchoscopy, exemplary cine MR, and evaluated the clinical relevance. Twenty-nine patients (2 follow-ups; mean age 61 years, age range 27-85 years) with suspected or verified tracheal stenosis or collapse (post-tracheotomy: n=17; neoplasm: n=5; other: n=7) underwent paired breath-hold inspiratory and expiratory spiral CT. Forty-five additional cine CT were performed at 1-4 levels (mean 1.5) during continuous respiration (increment 100 ms) to clarify respiratory collapse. The tracheal cross-sectional diameters of both techniques were calculated. Comparison with bronchoscopy, follow-up, and influence upon therapy were evaluated retrospectively. Exemplary comparison with cine MR (8 frames/s) was done in 3 cases. In addition to bronchoscopy, further information concerning localisation, extent, collapse, stability of the tracheal wall, distal portions of the stenosis and extraluminal compressions were obtained. A significantly higher degree and more pathological collapses (>50%) were seen using cine CT (38%) compared with paired spiral CT (13%; degree: p<0.0001; number: p<0.001). The findings changed the further therapeutic procedure in 16 of 29 patients. Further stenoses were excluded and bronchoscopy was verified in another 13 of 29. Temporal resolution of cine CT and cine MR is sufficient; however, spatial resolution of cine MR is inferior. Paired inspiratory and expiratory spiral CT localises tracheal stenoses and demonstrates relevant extraluminal compression. Significantly improved evaluation of respiratory collapse and further information of localised tracheal instability is obtained by cine CT. Cine MR promises more functional information especially due to free choice of imaging plane. (orig.)

  6. Positive end-expiratory pressure attenuates hemodynamic effects induced by an overload of inspiratory muscles in patients with COPD

    Directory of Open Access Journals (Sweden)

    Schaper-Magalhães F

    2017-10-01

    Full Text Available Flavia Schaper-Magalhães,1 José Felippe Pinho,1 Carolina Andrade Bragança Capuruço,2 Maria Glória Rodrigues-Machado1 1Medical Sciences Faculty of Minas Gerais, Post-Graduation Program in Health Sciences, Belo Horizonte, Brazil; 2Department of Cardiology, Clinics Hospital, Federal University of Minas Gerais, Belo Horizonte, Brazil Background: Inspiratory muscle training (IMT using a Threshold® device is commonly used to improve the strength and endurance of inspiratory muscles. However, the effect of IMT, alone or with positive end-expiratory pressure (PEEP, on hemodynamic parameters in patients with chronic obstructive pulmonary disease (COPD remains unknown.Objective: To assess the effects of an overload of inspiratory muscles using IMT fixed at 30% of the maximal inspiratory pressure (MIP, and IMT associated with 5 cmH2O of PEEP (IMT + PEEP, on the echocardiographic parameters in healthy subjects and patients with COPD.Methods: Twenty patients with COPD (forced expiratory volume in 1 second 53.19±24.71 pred% and 15 age-matched healthy volunteers were evaluated using spirometry, MIP, the COPD assessment test (CAT, and the modified Medical Research Council (mMRC dyspnea scale. The E- (fast-filling phase and A- (atrial contraction phase waves were evaluated at the tricuspid and mitral valves during inspiration and expiration in the following sequence: at basal conditions, using IMT, and using IMT + PEEP.Results: Patients with COPD had reduced MIPs versus the control group. Ten patients had CAT scores <10 and 12 patients had mMRC scores <2. E-wave values at the mitral valve were significantly decreased with IMT during the inspiratory phase in both groups. These effects were normalized with IMT + PEEP. During the expiratory phase, use of IMT + PEEP normalized the reduction in E-wave values in the COPD group. During inspiration at the tricuspid valve, reduction in E-wave values during IMT was normalized by IMT + PEEP in COPD group. During the

  7. Early warning and prevention of pneumonia in acute leukemia by patient education, spirometry, and positive expiratory pressure

    DEFF Research Database (Denmark)

    Møller, Tom; Moser, Claus; Adamsen, Lis

    2016-01-01

    fever, emphasizing the need to approach infection protection with complementary efforts. In a randomized controlled design, we examined the applicability of patient-performed daily spirometry [forced expiratory volume in one second (FEV1)] as an early warning tool and explored the effectiveness...... in their continuous daily measurement of FEV1 and use of PEP. Daily measures of FEV1 may be an important early warning tool for assessment of pulmonary deterioration during critical phases of neutropenia. We suggest that strategic patient education in the use of spirometry and PEP should be part of standard of care...

  8. Alveolar Tidal recruitment/derecruitment and Overdistension During Four Levels of End-Expiratory Pressure with Protective Tidal Volume During Anesthesia in a Murine Lung-Healthy Model.

    Science.gov (United States)

    Soares, Joao Henrique Neves; Carvalho, Alysson Roncally; Bergamini, Bruno Curty; Gress, Maria Alice Kuster; Jandre, Frederico Caetano; Zin, Walter Araujo; Giannella-Neto, Antonio

    2018-02-12

    We compared respiratory mechanics between the positive end-expiratory pressure of minimal respiratory system elastance (PEEP minErs ) and three levels of PEEP during low-tidal-volume (6 mL/kg) ventilation in rats. Twenty-four rats were anesthetized, paralyzed, and mechanically ventilated. Airway pressure (P aw ), flow (F), and volume (V) were fitted by a linear single compartment model (LSCM) P aw (t) = E rs  × V(t) + R rs  × F(t) + PEEP or a volume- and flow-dependent SCM (VFDSCM) P aw (t) = (E 1  + E 2  × V(t)) × V(t) + (K 1  + K 2  × |F(t)|) × F(t) + PEEP, where E rs and R rs are respiratory system elastance and resistance, respectively; E 1 and E 2 × V are volume-independent and volume-dependent E rs , respectively; and K 1 and K 2  × F are flow-independent and flow-dependent R rs , respectively. Animals were ventilated for 1 h at PEEP 0 cmH 2 O (ZEEP); PEEP minErs ; 2 cmH 2 O above PEEP minErs (PEEP minErs+2 ); or 4 cmH 2 O above PEEP minErs (PEEP minErs+4 ). Alveolar tidal recruitment/derecruitment and overdistension were assessed by the index %E 2  = 100 × [(E 2  × V T )/(E 1  + |E 2 | × V T )], and alveolar stability by the slope of E rs (t). %E 2 varied between 0 and 30% at PEEP minErs in most respiratory cycles. Alveolar Tidal recruitment/derecruitment (%E 2   30) were predominant in the absence of PEEP and in PEEP levels higher than PEEP minErs , respectively. The slope of E rs (t) was different from zero in all groups besides PEEP minErs+4 . PEEP minErs presented the best compromise between alveolar tidal recruitment/derecruitment and overdistension, during 1 h of low-V T mechanical ventilation.

  9. Limiting oxygen concentration for extinction of upward spreading flames over inclined thin polyethylene-insulated NiCr electrical wires with opposed-flow under normal- and micro-gravity

    KAUST Repository

    Hu, Longhua

    2016-10-02

    Materials, such as electrical wire, used in spacecraft must pass stringent fire safety standards. Tests for such standards are typically performed under normal gravity conditions and then extended to applications under microgravity conditions. The experiments reported here used polyethylene (PE)-insulated (thickness of 0.15 mm) Nichrome (NiCr)-core (diameter of 0.5 mm) electrical wires. Limiting oxygen concentrations (LOC) at extinction were measured for upward spreading flame at various forced opposed-flow (downward) speeds (0−25 cm/s) at several inclination angles (0−75°) under normal gravity conditions. The differences from those previously obtained under microgravity conditions were quantified and correlated to provide a reference for the development of fire safety test standards for electrical wires to be used in space exploration. It was found that as the opposed-flow speed increased for a specified inclination angle (except the horizontal case), LOC first increased, then decreased and finally increased again. The first local maximum of this LOC variation corresponded to a critical forced flow speed resulted from the change in flame spread pattern from concurrent to counter-current type. This critical forced flow speed correlated well with the buoyancy-induced flow speed component in the wire\\'s direction when the flame base width along the wire was used as a characteristic length scale. LOC was generally higher under the normal gravity than under the microgravity and the difference between the two decreased as the opposed-flow speed increases, following a reasonably linear trend at relatively higher flow speeds (over 10 cm/s). The decrease in the difference in LOC under normal- and microgravity conditions as the opposed-flow speed increases correlated well with the gravity acceleration component in the wire\\'s direction, providing a measure to extend LOC determined by the tests under normal gravity conditions (at various inclination angles and opposed-flow

  10. Interpersonal Transport of Expiratory Aerosols among Three Manikins in a Full-Scale Test Room

    DEFF Research Database (Denmark)

    Liu, Li; Nielsen, Peter Vilhelm; Jensen, Rasmus Lund

    2014-01-01

    installed to induce fresh air without generating sensible drafts in an occupied zone with fully mixing flow. The exposures of two target manikins to aerosols exhaled by one susceptible manikin were measured. Tracer gas N2O was used to simulate droplet nuclei. Comparisons on different mutual distances were...

  11. High Flow Nasal Cannula Therapy for Improving Obstructive Sleep Apnea: A Case Report

    Directory of Open Access Journals (Sweden)

    Se Joong Kim

    2015-06-01

    Full Text Available Although continuous positive airway pressure is the treatment of choice for obstructive sleep apnea, its compliance is low. Therefore, alternative therapeutic strategies are often required. High flow nasal cannula therapy uses an air compressor to deliver a constant flow of oxygen via the nasal cannula at a maximum of 60 L/m. It can produce positive end expiratory pressure and increase end expiratory pharyngeal pressure, which can help to alleviate upper airway obstruction. This is a case report of high flow nasal cannula therapy for a 71 year-old man. He had an obstructive sleep apnea and severe desaturation but failed to use continuous positive airway pressure. He underwent titration with high flow nasal cannula under polysomnography. Using high flow nasal cannula at an airflow of 45 L/m, his apnea-hypopnea, respiratory arousal and oxygen desaturation were improved. Importantly, he is very compliant with high flow nasal cannula therapy.

  12. Effect of simultaneous application of postural techniques and expiratory muscle strength training on the enhancement of the swallowing function of patients with dysphagia caused by parkinson?s disease

    OpenAIRE

    Byeon, Haewon

    2016-01-01

    [Purpose] This study aimed to investigate the effect of simultaneous application of postural techniques and expiratory muscle strength training on the enhancement of the swallowing function of patients with dysphagia caused by Parkinson?s disease. [Subjects and Methods] The subjects of this study were 18 patients who received simultaneous application of postural techniques and expiratory muscle strength training and 15 patients who received expiratory muscle strength training only. Postural t...

  13. Flow Resistance in Open Channels and Limits of Applicability of Manning's Formula; Resistencia al flujo en canales y limites de aplicabilidad de la formula de manning

    Energy Technology Data Exchange (ETDEWEB)

    Aldama, Alvaro A; R Ocon, Afredo [Instituto Mexicano de Tecnologia del Agua, Jiutepec, Morelos (Mexico)

    2002-03-01

    The concepts involved in the estimation of flow resistance in open channels are reviewed. In particular, of expressions for the friction factor that allow the derivation of expressions for the friction factor that appears in Darcy-Weisbach's formula for circular channels flowing full or at a depth equal half the diameter, and for wide channels, conveying hydraulically rough, fully turbulent flow. The results of such analyses show that it is possible to avoid adjustments to the numerical values that appear in Colebrook's formula, in order to reproduce experimental data. They also make it possible to explain the empirical dispersion observed in the values of the parameters of an expression used to estimate the Darcy-Weisbach friction coefficient for wide channels. On the basis of these results, the range of validity for Manning's formula is determined. Finally, additional evidence is provided in the estimation of flow resistance in open channels, being well represented by the hydraulic radius alone. This observation allows to foresees the possibility of developing a universally valid formula for the Darcy-Weisbach friction factor, applicable to flow in open channels. [Spanish] Se revisan los conceptos involucrados en la estimacion de la resistencia al flujo en canales. En particular, se senalan los inconvenientes de la popular formula de Manning. Tambien se presentan analisis teoricos que permiten determinar expresiones para el factor de friccion de la formula de Darcy-Weisbach para canales circulares trabajando llenos a la mitad, y para canales anchos conduciendo flujo hidraulicamente rugoso con turbulencia desarrollada. Se demuestra que los resultados de dichos analisis permiten evitar hacer ajustes en los valores numericos que aparecen en la formula de Colebrook, a fin de reproducir observaciones experimentales. Asimismo, hacen posible explicar la dispersion experimental en los valores de los parametros que aparecen en una expresion para el calculo

  14. Evidence of Zonal-Flow-Driven Limit-Cycle Oscillations during L-H Transition and at H-mode Pedestal of a New Small-ELM Regime in EAST

    DEFF Research Database (Denmark)

    Xu, G.; Wang, H.; Guo, H.

    Small-amplitude edge localized oscillations have been observed, for the first time, in EAST preceding the L-H transition at marginal input power, which manifest themselves as dithering in the divertor D signals at a frequency under 4 kHz, much lower than the GAM frequency. Detailed measurements...... providing a direct evidence of the zonal flows for the L-H transition at marginal input power. Furthermore, near the transition threshold sawtooth heat pulses appear to periodically enhance the dithering, finally triggering the L-H transition after a big sawtooth crash. The zonal flow induced limit...... link between them. A novel predator-prey model, incorporating the evolution of zonal flows, pressure gradient and turbulences at two different frequency ranges, has been developed and successfully reproduced the key features of this newly observed small-ELM regime....

  15. Determination of fatty acid oxidation in premature infants by means of /sup 13/CO/sub 2/ expiratory tests with simultaneous, continuous infusion of /sup 13/C-triolein. Bestimmung der Fettsaeureoxidation Fruehgeborener mit dem /sup 13/CO/sub 2/-Atemtest waehrend kontinuierlicher /sup 13/C-Triolein-Infusion

    Energy Technology Data Exchange (ETDEWEB)

    Broesicke, H.

    1987-01-01

    It was the purpose of this long-term test to develop a method of determining the parameters of metabolism in isotopic flow equilibrium adapted to the specific conditions of intravenous feeding. The most important requirement to be met for this /sup 13/CO/sub 2/ expiratory test is constant supply of the substrate, and this condition is fulfilled by the parenteral alimentation of premature infants or newborn babies, so that the study was carried out on this group of patients. (orig./MG) With 37 figs., 14 tabs.

  16. Peak flow variation in childhood asthma : Relationship to symptoms, atopy, airways obstruction and hyperresponsiveness

    NARCIS (Netherlands)

    Brand, PLP; Duiverman, EJ; Postma, DS; Waalkens, HJ; Kerrebijn, KF; vanEssenZandvliet, EEM; Quanjer, PH; Sluiter, HJ; Pouw, EM; Schoonbrood, DFME; Roos, CM; Jansen, HM; DeGooijer, A; Kerstjens, HAM; vanderMark, TW; Koeter, GH; deJong, PM; Sterk, PJ; Weaver, AMJ; Dijkman, JH; Dekhuijzen, PNR; Folgering, HTM; vanHerwaarden, CLA; Overbeek, SE; Bogaard, JM; Hilvering, C; Gans, SJ; Mengelers, HJJ; vanderBruggenBogaarts, BAHA; Kreukniet, J; Kouwenberg, JM; Prinsen, JE; Gerritsen, J; Knol, K; deMonchy, JGR; Dekker, FW; Kaptein, AA; Merkus, PJFM; Pocock, SJ; Hughes, MD; Robinson, NJ; Bleecker, ER; Meyers, DA

    Although home recording of peak expiratory flow (PEF) is considered useful in managing asthma, little is known about the relationship of PEF variation to other indicators of disease activity, We examined the relationship of PEF variation, expressed in various ways, to symptoms, atopy, level of lung

  17. The Effect of a Single Cigarette Puff on Air Flow in the Lungs | Iyawe ...

    African Journals Online (AJOL)

    Peak expiratory flow rate (PEFR) was measured in 160 apparently healthy males, 15 50 years of age, consisting of 60 non-smokers (control) and 100 who volunteered to smoke (experimental subjects). Out of the 100 subjects, 50 who were also non-smokers smoked a cigarette through a single suck (puff). Another 50 who ...

  18. Impacts of Modelling Simplifications on Predicted Dispersion of Human Expiratory Droplets

    DEFF Research Database (Denmark)

    Liu, Li; Nielsen, Peter Vilhelm; Xu, Chunwen

    2016-01-01

    simplifying the room air condition into isothermal condition, or neglecting the body plume of the manikin. It will also change the microenvironment completely by simplifying the shape of human grid in to a robot shape. The trajectories of both the exhalation airflows and droplet nuclei are significantly...... different from a detailed shape of human body and mouth........ The exhalation airflows are compared and validated by measurement results of human subjects. The flow field between two manikins are found significantly influenced by their exhalation airflows. Mono-dispersed droplets with an initial diameter of 10 μm are released from one breathe of a manikin. All droplets...

  19. Hypercapnia attenuates inspiratory amplitude and expiratory time responsiveness to hypoxia in vagotomized and vagal-intact rats

    Science.gov (United States)

    Tin, Chung; Song, Gang; Poon, Chi-Sang

    2012-01-01

    A negative influence of central chemosensitivity on peripheral chemoreflex response has been demonstrated recently in a decerebrate-vagotomized rat preparation in situ with separate carotid body and brainstem perfusions. Here, we report similar negative influences of hypercapnia on the hypoxic respiratory response in anesthetized, spontaneously breathing rats before and after vagotomy and anesthetized, artificially ventilated rats after vagotomy. Baseline breathing patterns and responsiveness to hypercapnia and hypoxia varied widely between the three respiratory modes. Despite this, the responses in inspiratory amplitude and expiratory duration (and hence respiratory frequency and neural ventilation) to hypoxia varied inversely with the background CO2 level in all three groups. Results demonstrate a hypoadditive hypercapnic-hypoxic interaction in vivo that resembles the hypoadditive central-peripheral chemoreceptor interaction in situ for these respiratory variables in the rat, regardless of differences in vagal feedback, body temperature and ventilation method. These observations stand in contrast to previous reports of hyperadditive peripheral-central chemoreceptor interaction. PMID:22326640

  20. Special Course on Shock-Wave/Boundary-Layer Interactions in Supersonic and Hypersonic Flows (Interactions entre Ondes de Choc et Couches Limites dans les Ecoulements Supersoniques et Hpersoniques).

    Science.gov (United States)

    1993-08-01

    Laser Corp.) was used as the flow was well-mixed in the wind tunnel stilling a light source. More recently, a 5-Watt Argon -Ion chamber by capturing...component capability, the ve- scattering mode. For all the tests presented here, the locimeter is equipped with two identical Argon lasers that forward...Directour dui Service des=oe o~us LUXEMBOURG Mmisirede l Ddw NVoireldgique Ottawa, Ontario KIA 0K2 I4ORVEGE DANEMAIU( Norwegia Defence Research

  1. Microwave plasma ion sources for selected ion flow tube mass spectrometry: Optimizing their performance and detection limits for trace gas analysis

    Czech Academy of Sciences Publication Activity Database

    Španěl, Patrik; Dryahina, Kseniya; Smith, D.

    2007-01-01

    Roč. 267, 1-3 (2007), s. 117-124 ISSN 1387-3806 R&D Projects: GA ČR GA202/06/0776 Institutional research plan: CEZ:AV0Z40400503 Keywords : microwave plasma ion source * selected ion flow tube mass spectrometry * SIFT-MS * breath analysis Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.411, year: 2007

  2. Quantitative assessment of cross-sectional area of small pulmonary vessels in patients with COPD using inspiratory and expiratory MDCT

    Energy Technology Data Exchange (ETDEWEB)

    Matsuura, Yukiko, E-mail: matsuyuki_future@yahoo.co.jp [Department of Respirology, Graduate School of Medicine, Chiba University, Chiba 260-8670 Japan (Japan); Kawata, Naoko, E-mail: chumito_03@yahoo.co.jp [Department of Respirology, Graduate School of Medicine, Chiba University, Chiba 260-8670 Japan (Japan); Yanagawa, Noriyuki, E-mail: yanagawa@ho.chiba-u.ac.jp [Department of Respirology, Graduate School of Medicine, Chiba University, Chiba 260-8670 Japan (Japan); Sugiura, Toshihiko, E-mail: sugiura@js3.so-net.ne.jp [Department of Respirology, Graduate School of Medicine, Chiba University, Chiba 260-8670 Japan (Japan); Sakurai, Yoriko, E-mail: yoliri@nifty.com [Department of Respirology, Graduate School of Medicine, Chiba University, Chiba 260-8670 Japan (Japan); Sato, Misuzu, E-mail: mis_misuzu@yahoo.co.jp [Department of Respirology, Graduate School of Medicine, Chiba University, Chiba 260-8670 Japan (Japan); Iesato, Ken, E-mail: iesato_k@yahoo.co.jp [Department of Respirology, Graduate School of Medicine, Chiba University, Chiba 260-8670 Japan (Japan); Terada, Jiro, E-mail: jirotera@chiba-u.jp [Department of Respirology, Graduate School of Medicine, Chiba University, Chiba 260-8670 Japan (Japan); Sakao, Seiichiro, E-mail: sakao@faculty.chiba-u.jp [Department of Respirology, Graduate School of Medicine, Chiba University, Chiba 260-8670 Japan (Japan); Tada, Yuji, E-mail: ytada@faculty.chiba-u.jp [Department of Respirology, Graduate School of Medicine, Chiba University, Chiba 260-8670 Japan (Japan); Tanabe, Nobuhiro, E-mail: ntanabe@faculty.chiba-u.jp [Department of Respirology, Graduate School of Medicine, Chiba University, Chiba 260-8670 Japan (Japan); Suzuki, Yoichi, E-mail: ysuzuki@faculty.chiba-u.jp [Department of public Health, Graduate School of Medicine, Chiba University, Chiba 260-8670 Japan (Japan); Tatsumi, Koichiro, E-mail: tatsumi@faculty.chiba-u.jp [Department of Respirology, Graduate School of Medicine, Chiba University, Chiba 260-8670 Japan (Japan)

    2013-10-01

    Objectives: Structural and functional changes in pulmonary vessels are prevalent at the initial stages of chronic obstructive pulmonary disease (COPD). These vascular alterations can be assessed using cross-sectional area (CSA) of small pulmonary vessels. However, neither in non-COPD smokers nor in COPD patients it has been defined whether the structural changes of pulmonary vessels detected by paired inspiratory and expiratory CT scans are associated with emphysematous changes. We quantified the CSA and low attenuation area (LAA) and evaluated the changes in these parameters in the inspiratory and expiratory phases. Materials and methods: Fifty consecutive non-COPD smokers and COPD patients were subjected to multi detector-row CT and the percentage of vessels with a CSA less than 5 mm{sup 2} as well as the percentage LAA for total lung area (%CSA < 5, %LAA, respectively) were calculated. Results: The %CSA < 5 correlated negatively with %LAA. The %CSA < 5 was lower in COPD patients with emphysema as compared with non-COPD smokers and COPD patients with or without mild emphysema. In addition, the %CSA < 5 was lower in the no/mild emphysema subgroup as compared with non-COPD smokers. The respiratory phase change of %CSA < 5 in COPD patients was greater than that in non-COPD smokers. Conclusion: The percentage of small pulmonary vessels decreased as emphysematous changes increase, and this decrease was observed even in patients with no/mild emphysema. Furthermore, respiratory phase changes in CSA were higher in COPD patients than in non-COPD smokers.

  3. Inspiratory and expiratory HRCT findings in Behcet's disease and correlation with pulmonary function tests

    Energy Technology Data Exchange (ETDEWEB)

    Oezer, Caner [Department of Radiology, Mersin University, Faculty of Medicine, Mersin (Turkey)]. E-mail: cozer@mersin.edu.tr; Duce, Meltem Nass [Department of Radiology, Mersin University, Faculty of Medicine, Mersin (Turkey); Ulubas, Bahar [Department of Respiratory Disease, Mersin University, Faculty of Medicine, Mersin (Turkey); Bicer, Ali [Department of Physical Medicine and Rehabilitation, Mersin University, Faculty of Medicine, Mersin (Turkey); Tuersen, Uemit [Department of Dermatology, Mersin University, Faculty of Medicine, Mersin (Turkey); Apaydin, F. Demir [Department of Radiology, Mersin University, Faculty of Medicine, Mersin (Turkey); Yildiz, Altan [Department of Radiology, Mersin University, Faculty of Medicine, Mersin (Turkey); Camdeviren, Handan [Department of Biostatistics, Mersin University, Faculty of Medicine, Mersin (Turkey)

    2005-10-01

    Purpose: The purpose of our study was to describe the pulmonary parenchymal changes of Behcet's disease using high-resolution computed tomography and to correlate them with pulmonary function tests. Materials and methods: Thirty-four patients with Behcet's disease (18 men, 16 women), 3 of whom were symptomatic, were included as the study group. Four of 34 patients were smokers. Twenty asymptomatic volunteers (12 men, 8 women), 4 of whom were smokers, constituted the control group. The pulmonary function tests and high-resolution computed tomography were performed for both groups. Results: Inspiratory high-resolution computed tomography findings were abnormal in nine patients (26.5%) of the study group. In eight patients, there were multiple abnormalities, whereas one patient had only one abnormality. Pleural thickening and irregularities, major fissure thickening, emphysematous changes, bronchiectasis, parenchymal bands, and irregular densities, and parenchymal nodules were the encountered abnormalities. Inspiratory high-resolution computed tomography scans were normal in the control group. On expiratory scans, there was statistically significant difference between study group and control group when air trapping, especially grades 3 and 4, was compared (P < 0.01). Pulmonary function tests of both the study and the control groups were in normal ranges, and there was no statistically significant difference between the two groups according to pulmonary function tests (P > 0.05). Discussion and conclusion: High-resolution computed tomography is sensitive in the demonstration of pulmonary changes in patients with Behcet's disease. End-expiratory high-resolution computed tomography examination is very useful and necessary to show the presence of air trapping, thus the presence of small airway disease, even if the patient is asymptomatic or has normal pulmonary function tests.

  4. Incidence of tracheobronchomalacia associated with pulmonary emphysema. Detection with paired inspiratory-expiratory multidetector computed tomography using a low-dose technique

    International Nuclear Information System (INIS)

    Inoue, Masanori; Hasegawa, Ichiro; Nakano, Keiko; Yamaguchi, Kazuhiro; Kuribayashi, Sachio

    2009-01-01

    The purpose of this study was to evaluate the frequency of tracheobronchomalacia (TBM) associated with pulmonary emphysema with paired inspiratory-expiratory multidetector computed tomography (MDCT) using a low-dose technique. This study included 56 consecutive patients (55 men, 1 woman; mean age 68.9 years) with pulmonary emphysema who had undergone paired inspiratory-expiratory CT scanning with a low-dose technique (40 mA). All images were retrospectively examined by two thoracic radiologists in a blinded fashion. The diagnosis of TBM was based on the standard criterion of >50% reduction in the cross-sectional area of the tracheobronchial lumen at the end-expiratory phase. A mild TBM criterion of >30% reduction was also reviewed. All patients underwent pulmonary function tests. The relation between the forced expiratory volume in 1 s (FEV 1.0% ) and TBM was statistically analyzed. Four (7.1%) and eight (14.3%) patients were diagnosed as TBM based on the standard and mild criteria, respectively. In four patients, the percentages of luminal narrowing were 63.4% and 51.2%, respectively for tracheomalacia and 59.2% and 62.0%, respectively, for bronchomalacia. The FEV 1.0% values between patients with and without TBM showed no statistical difference. The incidence of TBM associated with pulmonary emphysema was 7.1% with the standard criterion. It is possible that TBM has been underdiagnosed in a number of patients with pulmonary emphysema. (author)

  5. Influence of Changing the Diameter of the Bubble Generator Bottle and Expiratory Limb on Bubble CPAP: An in vitro Study

    Directory of Open Access Journals (Sweden)

    Chun-Shan Wu

    2012-12-01

    Conclusion: The size and submergence depth of an expiratory limb of a CPAP circuit, the diameter of the bubble generator bottle, and the compliance of the model lung all influence the magnitude and frequency of the transmitted pressure waveform. Therefore, these factors may affect lung volume recruitment and breathing efficiency in bubble CPAP.

  6. Associations between positive end-expiratory pressure and outcome of patients without ARDS at onset of ventilation: a systematic review and meta-analysis of randomized controlled trials

    NARCIS (Netherlands)

    Serpa Neto, Ary; Filho, Roberto Rabello; Cherpanath, Thomas; Determann, Rogier; Dongelmans, Dave A.; Paulus, Frederique; Tuinman, Pieter Roel; Pelosi, Paolo; de Abreu, Marcelo Gama; Schultz, Marcus J.

    2016-01-01

    The aim of this investigation was to compare ventilation at different levels of positive end-expiratory pressure (PEEP) with regard to clinical important outcomes of intensive care unit (ICU) patients without acute respiratory distress syndrome (ARDS) at onset of ventilation. Meta-analysis of

  7. Comparative effects of arotinolol, labetalol and propranolol on regional myocardial dysfunction induced by flow-limiting coronary stenosis in anesthetized dogs.

    Science.gov (United States)

    Noguchi, K; Kato, T; Kinjo, N; Moromizato, H; Sakanashi, M

    1990-07-01

    Effects of arotinolol, a combined alpha- and beta-adrenoceptor blocking agent, on regional myocardial dysfunction produced by severe coronary stenosis in anesthetized dogs were examined and compared with those of labetalol and propranolol. Doses of these three antagonists were selected to produce a comparable degree of the negative chrono- and inotropic effect but a different potency of alpha-adrenoceptor blockade (labetalol greater than arotinolol). Regional myocardial function measured as segment shortening (%SS) was decreased to around 2-3% by constriction of the left circumflex coronary artery (LCX), and then drug or saline was administered i.v. The stenosis of LCX was released 30 min after the administration. No significant alteration in hemodynamic and contractility parameters was seen as compared to the predrug value up to at least 30 min after saline i.v. Arotinolol and propranolol both reduced heart rate and peak positive left ventricular dP/dt (LVdP/dt) without a significant change in LCX flow. Concomitantly, %SS distal to a coronary stenosis was significantly improved by arotinolol and propranolol. On the other hand, labetalol significantly reduced LCX flow probably due to systemic hypotension and failed to improve %SS in the ischemic area, although the agent markedly decreased heart rate and LVdP/dt. These results indicate that arotinolol improves impaired regional myocardial function distal to a coronary stenosis in a similar manner with propranolol.

  8. The need for standardisation of peak flow charts

    OpenAIRE

    Reddel, H; Vincent, S; Civitico, J

    2005-01-01

    Peak expiratory flow (PEF) monitoring is recommended in asthma guidelines as a tool for assessing severity, monitoring response to treatment, detecting exacerbations, identifying triggers, and providing objective justification for treatment to the patient, but some clinicians have expressed concerns about its relevance in the management of asthma. We have identified a sevenfold variation in the scale of existing PEF charts, with resulting wide variation in the appearance of the same PEF date ...

  9. Study of the influence of the turbulent boundary conditions of a flow with parietal injection; Etude de l'influence des conditions aux limites turbulentes d'un ecoulement avec injection parietale

    Energy Technology Data Exchange (ETDEWEB)

    Chaouat, B.

    1998-07-01

    Numerical simulations of flows inside a solid propellant rocket engine with parietal injection are performed using the numerical resolution of Navier-Stokes equations in a k-{epsilon} turbulence model. Boundary conditions are defined considering laminar and turbulent fluid injections on the wall. In parallel, a Couette-type model is used to determine the velocity profile near the wall and the wall constraint for a laminar fluid injection. An analysis of simulations shows the influence of boundary conditions on the transition of the flow from the laminar to the turbulent regime, on the velocity profile near the wall, and on the evolution of Reynolds pressures. The average velocity profile is well reproduced but the first-order k-{epsilon} turbulence model shows limitations for the reproduction of turbulent pressure levels. A second-order Reynolds pressure model should be more appropriate. (J.S.)

  10. Relationship between respiratory impedance and positive end-expiratory pressure in mechanically ventilated neonates.

    Science.gov (United States)

    Dellacà, Raffaele L; Veneroni, C; Vendettuoli, V; Zannin, E; Matassa, P G; Pedotti, A; Colnaghi, M; Mosca, F

    2013-03-01

    To evaluate the feasibility of forced oscillation technique (FOT) measurements at the bedside and to describe the relationship between positive end-expiration pressure (PEEP) and lung mechanics in different groups of ventilated infants. Twenty-eight infants were studied: 5 controls, 16 newborns with respiratory distress syndrome (RDS) and 7 chronically ventilated newborns that developed bronchopulmonary dysplasia. An incremental/decremental PEEP trial was performed by changing PEEP in 1-min steps of 1 cmH(2)O between 2 and 10 cmH(2)O. Forced oscillations at 5 Hz were superimposed on the ventilator waveform. Pressure and flow, measured at the inlet of the ETT, were used to compute resistance (Rrs) and reactance (Xrs). In controls Rrs and Xrs were on average 41 ± 21 and -22 ± 6 cmH(2)O s/l respectively and were almost unaffected by PEEP. RDS infants presented similar Rrs (48 ± 25 cmH(2)O s/l) and reduced Xrs (-71 ± 19 cmH(2)O s/l) at the beginning of the trial. Two behaviours were observed as PEEP was increased: in extremely low birth weight infants Xrs decreased with PEEP with marked hysteresis; in very low and low birth weight infants Xrs and Rrs were less PEEP dependent. Chronically ventilated infants had very high Rrs and very negative Xrs values at very low PEEPs (121 ± 41 and -95 ± 13 cmH(2)O s/l at PEEP = 2 cmH(2)O) that markedly changed as PEEP exceeded 3-4 cmH(2)O. Rrs and Xrs measurement in preterm newborns is feasible, and data are representative of the lung mechanics and very sensitive to its changes with PEEP, making FOT a promising technique for the non-invasive bedside titration of mechanical ventilation in preterm newborns.

  11. Kinetics of 13N-ammonia uptake in myocardial single cells indicating potential limitations in its applicability as a marker of myocardial blood flow

    International Nuclear Information System (INIS)

    Rauch, B.; Helus, F.; Grunze, M.; Braunwell, E.; Mall, G.; Hasselbach, W.; Kuebler, W.

    1985-01-01

    To study kinetics and principles of cellular uptake of 13 N-ammonia, a marker of coronary perfusion in myocardial scintigraphy, heart muscle cells of adult rats were isolated by perfusion with collagenase and hyaluronidase. Net uptake of 13 N, measured by flow dialysis, reached equilibrium within 20 sec in the presence of sodium bicarbonate and carbon dioxide (pH 7.4, 37 degrees C). Total extraction, 80 sec after the reaction start, was 786 +/- 159 mumol/ml cell volume. Cells destroyed by calcium overload were unable to extract 13 N-ammonia. Omission of bicarbonate and carbon dioxide reduced total extraction to 36% of control. 13 N-Ammonia uptake could also be reduced by 50 muM 4,4' diisothiocyanostilbene 2,2' disulfonic acid, by 100 micrograms/ml 1-methionine sulfoximine, and by preincubation with 5 muM free oleic acid. These results indicate that in addition to metabolic trapping by glutamine synthetase, the extraction of 13 N-ammonia by myocardial cells is influenced by cell membrane integrity, intracellular-extracellular pH gradient, and possibly an anion exchange system for bicarbonate. For this reason, the uptake of 13 N-ammonia may not always provide a valid measurement of myocardial perfusion

  12. A single photon emission computed tomograph based on a limited dumber of detectors for fluid flow visualization; Tomographie d'emission gamma a partir d'un nombre limite de detecteurs appliquee a la visualisation d'ecoulements

    Energy Technology Data Exchange (ETDEWEB)

    Legoupil, S

    1999-07-01

    We present in this work a method for fluid flow visualization in a system using radioactive tracers. The method is based on single photon emission computed tomography techniques, applied to a limited number of discrete detectors. We propose in this work a method for the estimation of the transport matrix of photons, associated to the acquisition system.This method is based on the modelization of profiles acquired for a set of point sources located in the imaged volume. Monte Carlo simulations allow to separate scattered photons from those directly collected by the system. The influence of the energy tracer is exposed. The reconstruction method is based on the maximum likelihood - expectation maximization algorithm. An experimental device, based on 36 detectors was realised for the visualization of water circulation in a vessel. A video monitoring allows to visualize the dye water tracer. Dye and radioactive tracers are injected simultaneously in a water flow circulating in the vessel. Reconstructed and video images are compared. Quantitative and qualitative analysis show that fluid flow visualization is feasible with a limited number of detectors. This method can be applied for system involving circulations of fluids. (author)

  13. Pulmonary sarcoidosis: correlation of expiratory high-resolution CT findings with inspiratory patterns and pulmonary function tests

    International Nuclear Information System (INIS)

    Magkanas, E.; Voloudaki, A.; Bouros, D.; Prassopoulos, P.; Alexopoulou, C.; Tzanakis, N.; Gourtsoyiannis, N.; Linardakis, M.

    2001-01-01

    Purpose: To assess the presence and extent of air trapping (AT) on chest high-resolution CT (HRCT) in sarcoidosis and to correlate such findings with patterns, lesion extent on inspiratory CT and pulmonary function tests (PFT). Material and Methods: Thirty patients with sarcoidosis underwent inspiratory and expiratory HRCT and PFT. HRCT images were evaluated for presence, distribution and AT extent as well as the predominant HRCT pattern and the extent of lesions at inspiration. Attenuation difference in the AT regions at expiration and at inspiration were calculated. The presence and extent of AT were correlated with PFT, extent of involvement and predominant inspiratory patterns. Results: AT was present in 25/30 patients with no lung zone predilection. AT was the only CT indication of pulmonary sarcoidosis in 3/30 patients who also had normal PFT. Attenuation difference between inspiration and expiration ranged from -40 HU to 106 HU. In 2 patients, a paradoxical decrease of lung attenuation was observed at expiration. A significant correlation was found between AT extent at expiration, with residual volume-total lung capacity ratio and residual volume. Conclusion: AT is an additional HRCT finding in sarcoidosis. AT may involve any lung zone, including costophrenic angles and may be the only CT feature of pulmonary sarcoidosis. Strong correlation is only found with PFT values that are specific for incomplete lung emptying at expiration

  14. Influence of Positive End-Expiratory Pressure on Myocardial Strain Assessed by Speckle Tracking Echocardiography in Mechanically Ventilated Patients

    Directory of Open Access Journals (Sweden)

    Federico Franchi

    2013-01-01

    Full Text Available Purpose. The effects of mechanical ventilation (MV on speckle tracking echocardiography- (STE-derived variables are not elucidated. The aim of the study was to evaluate the effects of positive end-expiratory pressure (PEEP ventilation on 4-chamber longitudinal strain (LS analysis by STE. Methods. We studied 20 patients admitted to a mixed intensive care unit who required intubation for MV and PEEP titration due to hypoxia. STE was performed at three times: (T1 PEEP = 5 cmH2O; (T2 PEEP = 10 cmH2O; and (T3 PEEP = 15 cmH2O. STE analysis was performed offline using a dedicated software (XStrain MyLab 70 Xvision, Esaote. Results. Left peak atrial-longitudinal strain (LS was significantly reduced from T1 to T2 and from T2 to T3 (. Right peak atrial-LS and right ventricular-LS showed a significant reduction only at T3 (. Left ventricular-LS did not change significantly during titration of PEEP. Cardiac chambers’ volumes showed a significant reduction at higher levels of PEEP (. Conclusions. We demonstrated for the first time that incremental PEEP affects myocardial strain values obtained with STE in intubated critically ill patients. Whenever performing STE in mechanically ventilated patients, care must be taken when PEEP is higher than 10 cmH2O to avoid misinterpreting data and making erroneous decisions.

  15. Expiratory CT in cigarette smokers: correlation between areas of decreased lung attenuation, pulmonary function tests and smoking history

    Energy Technology Data Exchange (ETDEWEB)

    Verschakelen, J.A.; Scheinbaum, K.; Bogaert, J.; Baert, A.L. [Department of Radiology, University Hospitals, Leuven (Belgium); Demedts, M.; Lacquet, L.L. [Department of Pneumology, University Hospitals, Leuven (Belgium)

    1998-10-01

    The aim of this study was to determine the correlation between cigarette-smoke-related bronchial disease and air trapping as assessed by expiratory high-resolution CT (HRCT) scans. Thirty healthy subjects (11 non-smokers, 7 ex-smokers for > 2 years, 12 current smokers; age range 35-55 years) with a smoking history between 0 and 28.5 pack-years underwent pulmonary function tests (PFT) and HRCT in inspiration and expiration in supine and prone position. The extent of air trapping was scored in ventral and dorsal aspects of the upper, middle and lower lung portions. In 24 subjects (7 non-smokers, 7 ex-smokers, 10 current smokers) areas of focal air trapping were found, and were present significantly more often in dependent lung portions (p < 0.05) compared with non-dependent portions. No significant differences were found between apical and basal lung zones. Scores of focal air trapping were not significantly different between smokers and ex-smokers, but were significantly lower (p < 0.05) in non-smokers and showed a significant (p < 0.0005) correlation with pack-years. The degree of air trapping was also associated with several lung function tests, especially RV, DLCO, FRC, FEV1 and FEV1/VC. Air trapping is seen in smokers with normal PFT and correlates with the severity of the smoking history, independently of current smoking status. (orig.) (orig.) With 4 figs., 4 tabs., 59 refs.

  16. Positive end-expiratory pressure optimization using electric impedance tomography in morbidly obese patients during laparoscopic gastric bypass surgery.

    Science.gov (United States)

    Erlandsson, K; Odenstedt, H; Lundin, S; Stenqvist, O

    2006-08-01

    Morbidly obese patients have an increased risk for peri-operative lung complications and develop a decrease in functional residual capacity (FRC). Electric impedance tomography (EIT) can be used for continuous, fast-response measurement of lung volume changes. This method was used to optimize positive end-expiratory pressure (PEEP) to maintain FRC. Fifteen patients with a body mass index of 49 +/- 8 kg/m(2) were studied during anaesthesia for laparoscopic gastric bypass surgery. Before induction, 16 electrodes were placed around the thorax to monitor ventilation-induced impedance changes. Calibration of the electric impedance tomograph against lung volume changes was made by increasing the tidal volume in steps of 200 ml. PEEP was titrated stepwise to maintain a horizontal baseline of the EIT curve, corresponding to a stable FRC. Absolute FRC was measured with a nitrogen wash-out/wash-in technique. Cardiac output was measured with an oesophageal Doppler method. Volume expanders, 1 +/- 0.5 l, were given to prevent PEEP-induced haemodynamic impairment. Impedance changes closely followed tidal volume changes (R(2) > 0.95). The optimal PEEP level was 15 +/- 1 cmH(2)O, and FRC at this PEEP level was 1706 +/- 447 ml before and 2210 +/- 540 ml after surgery (P depression in spite of a high PEEP level.

  17. High versus low positive end-expiratory pressure during general anaesthesia for open abdominal surgery (PROVHILO trial): a multicentre randomised controlled trial.

    Science.gov (United States)

    Hemmes, Sabrine N T; Gama de Abreu, Marcelo; Pelosi, Paolo; Schultz, Marcus J

    2014-08-09

    The role of positive end-expiratory pressure in mechanical ventilation during general anaesthesia for surgery remains uncertain. Levels of pressure higher than 0 cm H2O might protect against postoperative pulmonary complications but could also cause intraoperative circulatory depression and lung injury from overdistension. We tested the hypothesis that a high level of positive end-expiratory pressure with recruitment manoeuvres protects against postoperative pulmonary complications in patients at risk of complications who are receiving mechanical ventilation with low tidal volumes during general anaesthesia for open abdominal surgery. In this randomised controlled trial at 30 centres in Europe and North and South America, we recruited 900 patients at risk for postoperative pulmonary complications who were planned for open abdominal surgery under general anaesthesia and ventilation at tidal volumes of 8 mL/kg. We randomly allocated patients to either a high level of positive end-expiratory pressure (12 cm H2O) with recruitment manoeuvres (higher PEEP group) or a low level of pressure (≤2 cm H2O) without recruitment manoeuvres (lower PEEP group). We used a centralised computer-generated randomisation system. Patients and outcome assessors were masked to the intervention. Primary endpoint was a composite of postoperative pulmonary complications by postoperative day 5. Analysis was by intention-to-treat. The study is registered at Controlled-Trials.com, number ISRCTN70332574. From February, 2011, to January, 2013, 447 patients were randomly allocated to the higher PEEP group and 453 to the lower PEEP group. Six patients were excluded from the analysis, four because they withdrew consent and two for violation of inclusion criteria. Median levels of positive end-expiratory pressure were 12 cm H2O (IQR 12-12) in the higher PEEP group and 2 cm H2O (0-2) in the lower PEEP group. Postoperative pulmonary complications were reported in 174 (40%) of 445 patients in the higher

  18. Avaliação da pressão positiva expiratória final utilizando o aparelho fisioterápico Quake Evaluation of positive end expiratory pressure using a physiotherapy device called Quake

    Directory of Open Access Journals (Sweden)

    Cristiane Cenachi Coelho

    2009-12-01

    Full Text Available O objetivo deste estudo foi avaliar, em voluntários saudáveis, o valor médio da pressão positiva expiratória final (PEEP na utilização do recurso fisioterápico Quake, relativamente novo no mercado. Participaram 62 indivíduos de ambos os sexos, entre 18 e 30 anos, que foram submetidos a: prova de função pulmonar; avaliação do pico de fluxo expiratório, da sensação subjetiva de esforço (escala de Borg e da saturação de oxigênio; e à utilização do aparelho, acoplado a um manovacuômetro, para efetuar duas seqüências respiratórias, de 10 e 20 incursões por minuto, monitoradas por retroalimentação visual. Os dados foram tratados estatisticamente. Foi observada diferença significativa entre os valores das pressões geradas apenas na seqüência de 10 incursões por minuto (p=0,03. Na comparação das pressões entre as seqüências, os valores foram significativamente menores na de 10 incursões (29,42±8,04 cmH2O; p=0,03. Não foram encontradas correlações entre as pressões e as variáveis da espirometria, idade e pico de fluxo expiratório. Foi observada uma fraca correlação significativa antes (r=0,36; p=0,003 e depois (r=0,31; p=0,014 da seqüência de 20 incursões entre as pressões nessa seqüência e os escores de fadiga na escala de Borg, tendo o mesmo ocorido com a saturação de oxigênio. A PEEP gerada pelo Quake em indivíduos saudáveis varia de acordo com a frequência em incursões por minuto, sendo maior durante a seqüência mais rápida, que também gera maior cansaço.The aim of this study was to assess the mean positive end expiratory pressure (PEEP during use of the Quake, a relatively new device, in healthy volunteers. Participants were 62 subjects of both sexes aged 18 to 30 years old, who were submitted to: pulmonary function tests; expiratory peak flow evaluation; the Borg scale; assessment of oxygen saturation; and use of the device, coupled to a manometer, in two sequences, of 10 and 20

  19. Turbulence Considerations for Comparing Ecosystem Exchange over Old-Growth and Clear-Cut Stands For Limited Fetch and Complex Canopy Flow Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Wharton, S; Schroeder, M; Paw U, K T; Falk, M; Bible, K

    2009-01-08

    Carbon dioxide, water vapor and energy fluxes were measured using eddy covariance (EC) methodology over three adjacent forests in southern Washington State to identify stand-level age-effects on ecosystem exchange. The sites represent Douglas-fir forest ecosystems at two contrasting successional stages: old-growth (OG) and early seral (ES). Here we present eddy flux and meteorological data from two early seral stands and the Wind River AmeriFlux old-growth forest during the growing season (March-October) in 2006 and 2007. We show an alternative approach to the usual friction velocity (u*) method for determining periods of adequate atmospheric boundary layer (ABL) mixing based on the ratio of mean horizontal ({bar u}) and vertical ({bar w}) wind flow to a modified turbulent kinetic energy scale (uTKE). This new parameter in addition to footprint modeling showed that daytime CO{sub 2} fluxes (F{sub NEE}) in small clear-cuts (< 10 hectares) can be measured accurately with EC if micrometeorological conditions are carefully evaluated. Peak midday CO{sub 2} fluxes (F{sub NEE} = -14.0 to -12.3 {micro}mol m{sup -2} s{sup -1}) at OG were measured in April in both 2006 and 2007 before bud break when air and soil temperatures and vapor pressure deficit were relatively low, and soil moisture and light levels were favorable for photosynthesis. At the early seral stands, peak midday CO{sub 2} fluxes (F{sub NEE} = -11.0 to -8.7 {micro}mol m{sup -2} s{sup -1}) were measured in June and July while spring-time CO{sub 2} fluxes were much smaller (F{sub NEE} = -3.8 to -3.6 {micro}mol m{sup -2} s{sup -1}). Overall, we measured lower evapotranspiration (OG = 230 mm; ES = 297 mm) higher midday F{sub NEE} (OG F{sub NEE} = -9.0 {micro}mol m{sup -2} s{sup -1}; ES F{sub NEE} = -7.3 {micro}mol m{sup -2} s{sup -1}) and higher Bowen ratios (OG {beta} = 2.0. ES {beta} = 1.2) at the old-growth forest than at the ES sites during the summer months (May-August). Eddy covariance studies such as ours

  20. Inorganic Phosphate (Pi) Enhancement of Dark Respiration in the Pi-Limited Green Alga Selenastrum minutum (Interactions between H+/Pi Cotransport, the Plasmalemma H+-ATPase, and Dark Respiratory Carbon Flow).

    Science.gov (United States)

    Gauthier, D. A.; Turpin, D. H.

    1994-02-01

    Inorganic phosphate (Pi) enrichment of the Pi-limited green alga Selenastrum minutum in the dark caused a 2.5-fold increase in the rate of O2 consumption. Alkalization of the media during Pi assimilation was consistent with a H+/Pi cotransport mechanism with a stoichiometry of at least 2 H+ cotransported per Pi. Dark O2 consumption remained enhanced beyond the period of Pi assimilation and did not recover until the medium was reacidified. This result, coupled with an immediate decrease in adenylate energy charge following Pi enrichment, suggested that respiration is regulated by the ATP requirements of a plasmalemma H+-ATPase that is activated to maintain intracellular pH and provide proton motive force to power Pi uptake. Concentrations of tricarboxylic acid cycle intermediates decreased following Pi enrichment and respiratory CO2 efflux increased, indicating that the tricarboxylic acid cycle was activated to supply reductant to the mitochondrial electron transport chain. These results are consistent with direct inhibition of electron transport by ADP limitation. Enhanced rates of starch breakdown and increases in glycolytic metabolites indicated that respiratory carbon flow was activated to supply reductant to the electron transport chain and to rapidly assimilate Pi into metabolic intermediates. The mechanism that initiates glycolytic carbon flow could not be clearly identified by product:substrate ratios due to the complex nature of Pi assimilation. High levels of triose-P and low levels of phosphoenolpyruvate were the primary regulators of pyruvate kinase and phosphofructokinase, respectively.

  1. [ProSeal™laryngeal mask in normal weight and obese patients : oxygenation under pressure-controlled ventilation and different end-expiratory pressures].

    Science.gov (United States)

    Goldmann, K; Gerlach, M; Bornträger, C

    2011-10-01

    Most of the data on combining pressure-controlled ventilation (PCV) with positive end-expiratory pressure (PEEP) come from studies with an endotracheal tube (ETT) whereas data on utilization of PEEP with a laryngeal mask airway (LMA) are limited. The LMA-ProSeal® (PLMA) forms a more effective seal of the airway than the LMA-Classic™ (CLMA). The application of PEEP when PCV is used with the PLMA could have an impact on oxygenation in adult patients. For this study 148 patients with an mean age of 44 years (range18-65 years) and mean weight of 86 kg (range 49-120 kg) were recruited in 2 groups: group N ((Normal)): body-mass index (BMI) cmH(2)O, 5 cmH(2)O or 8 cmH(2)O PEEP. An arterial blood gas sample was taken 50 min after induction of anesthesia under an inspiratory oxygen fraction (F(I)O(2)) of 0.3. In the first part partial oxygen pressure (p(a)O(2)) under 0 cmH(2)O was compared with p(a)O(2) under 5 cmH(2)O and in the second part p(a)O(2) under 5 cmH(2)O was compared with p(a)O(2) under 8 cmH(2)O. A significant difference was set as pcmH(2)O. Both findings are in contrast to findings of studies using an ETT which suggests that higher pressures (40 cmH(2)O) are needed for recruitment of collapsed alveoli and higher PEEP (10 cmH(2)O) is needed to produce a clinically significant improvement in oxygenation in obese patients. The results of this study support data showing that the consequences of bronchopulmonary airway reactions known to occur with an ETT are less pronounced or absent when an LMA is used.

  2. Randomised controlled trial of weightlifting exercise in patients with chronic airflow limitation.

    OpenAIRE

    Simpson, K; Killian, K; McCartney, N; Stubbing, D G; Jones, N L

    1992-01-01

    BACKGROUND PATIENTS: with chronic airflow obstruction are often limited by muscle fatigue and weakness. As exercise rehabilitation programmes have produced modest improvements at best a study was designed to determine whether specific muscle training techniques are helpful. METHODS: Thirty four patients with chronic airflow limitation (forced expiratory volume in one second (FEV1) 38% of predicted values) were stratified for FEV1 to vital capacity (VC) ratio less than 40% and arterial oxygen ...

  3. Be-limiter experiment on ISX

    International Nuclear Information System (INIS)

    Mioduszewski, P.K.

    1984-01-01

    The relevance of this experiment to the JET experiment is described. Data on the following issues are given: (1) thermo-mechanical properties of the Be-limiter; (2) particle flow to limiter; (3) heat flow to the limiter; (4) limiter-plasma-wall interaction; (5) plasma properties/operation; (6) active control of plasma-limiter operation; and (7) fault conditions

  4. Impact of changes of positive end-expiratory pressure on functional residual capacity at low tidal volume ventilation during general anesthesia

    OpenAIRE

    Satoh, Daizoh; Kurosawa, Shin; Kirino, Wakaba; Wagatsuma, Toshihiro; Ejima, Yutaka; Yoshida, Akiko; Toyama, Hiroaki; Nagaya, Kei

    2012-01-01

    Purpose Several reports in the literature have described the effects of positive end-expiratory pressure (PEEP) level upon functional residual capacity (FRC) in ventilated patients during general anesthesia. This study compares FRC in mechanically low tidal volume ventilation with different PEEP levels during upper abdominal surgery. Methods Before induction of anesthesia (awake) for nine patients with upper abdominal surgery, a tight-seal facemask was applied with 2 cmH2O pressure support ve...

  5. Expiratory activation of abdominal muscle is associated with improved respiratory stability and an increase in minute ventilation in REM epochs of adult rats

    OpenAIRE

    Andrews, Colin G.; Pagliardini, Silvia

    2015-01-01

    Breathing is more vulnerable to apneas and irregular breathing patterns during rapid eye movement (REM) sleep in both humans and rodents. We previously reported that robust and recurrent recruitment of expiratory abdominal (ABD) muscle activity is present in rats during REM epochs despite ongoing REM-induced muscle atonia in skeletal musculature. To develop a further understanding of the characteristics of ABD recruitment during REM epochs and their relationship with breathing patterns and ir...

  6. CORRELATION OF SEVERITY OF APNOEA HYPOPNOEA INDEX (AHI WITH FORCED EXPIRATORY VOLUME 1 (FEV1 IN OVERLAP SYNDROME

    Directory of Open Access Journals (Sweden)

    Meenakshi Narasimhan

    2017-08-01

    Full Text Available BACKGROUND Overlap syndrome was first described by David Flenley in 1980 refers to the coexistence of Chronic Obstructive Pulmonary Disease (COPD and Obstructive Sleep Apnoea (OSA. The global prevalence of Overlap syndrome is 11-14% and 7.5% in India Overlap patients are at higher risk of developing Nocturnal desaturations, hypertension, congestive heart failure, stroke etc. resulting in greater mortality and morbidity. There are very few studies in India correlating factors like poor lung function, body mass index, high ESS score, MMRC dyspnea grading in COPD patients with OSA .Hence, this study was undertaken to correlate the association and severity of OSA using AHI with Forced Expiratory Volume in 1 sec (FEV1, Body Mass Index (BMI, Modified Medical Research Council dyspnea grade (MRC and high Epworth Sleepiness Scale (ESS. MATERIALS AND METHODS A prospective observational study, done in 66 COPD patients in Department of Respiratory Medicine, CHRI, Chennai. The diagnosis of COPD was based upon GOLD guidelines 2016. The OSA was diagnosed based on the American Academy of Sleep Medicine guidelines (AASMA. All COPD patients were subjected to detailed clinical history, thorough physical examination, ENT examination to rule out Upper airway obstruction. All patients were asked to fill up the Epworth sleepiness questionnaire. BMI was recorded. Dyspnea grading was done using MMRC scale. Patient was also subjected to Spirometry and overnight Polysomnography, RESULTS In patients with overlap syndrome, no correlation of statistical significance between the AHI and FEV1. Though, the grade of AHI showed an increase as the FEV1 decreased. Significant positive correlation was observed between AHI and MMRC as well as AHI and ESS. CONCLUSION In COPD patients FEV1 did not correlate with AHI grade and hence lung function cannot be used as predictor of OSA in COPD. However, simple clinical parameters like ESS and MMRC which show a positive correlation with AHI

  7. A fully automated approach for baby cry signal segmentation and boundary detection of expiratory and inspiratory episodes.

    Science.gov (United States)

    Abou-Abbas, Lina; Tadj, Chakib; Fersaie, Hesam Alaie

    2017-09-01

    The detection of cry sounds is generally an important pre-processing step for various applications involving cry analysis such as diagnostic systems, electronic monitoring systems, emotion detection, and robotics for baby caregivers. Given its complexity, an automatic cry segmentation system is a rather challenging topic. In this paper, a framework for automatic cry sound segmentation for application in a cry-based diagnostic system has been proposed. The contribution of various additional time- and frequency-domain features to increase the robustness of a Gaussian mixture model/hidden Markov model (GMM/HMM)-based cry segmentation system in noisy environments is studied. A fully automated segmentation algorithm to extract cry sound components, namely, audible expiration and inspiration, is introduced and is grounded on two approaches: statistical analysis based on GMMs or HMMs classifiers and a post-processing method based on intensity, zero crossing rate, and fundamental frequency feature extraction. The main focus of this paper is to extend the systems developed in previous works to include a post-processing stage with a set of corrective and enhancing tools to improve the classification performance. This full approach allows to precisely determine the start and end points of the expiratory and inspiratory components of a cry signal, EXP and INSV, respectively, in any given sound signal. Experimental results have indicated the effectiveness of the proposed solution. EXP and INSV detection rates of approximately 94.29% and 92.16%, respectively, were achieved by applying a tenfold cross-validation technique to avoid over-fitting.

  8. Comparison of intermittent positive pressure breathing and temporary positive expiratory pressure in patients with severe chronic obstructive pulmonary disease.

    Science.gov (United States)

    Nicolini, Antonello; Mollar, Elena; Grecchi, Bruna; Landucci, Norma

    2014-01-01

    Results supporting the use and the effectiveness of positive expiratory, pressure devices in chronic obstructive pulmonary disease (COPD) patients are still controversial, We have tested the hypothesis that adding TPEP or IPPB to standard pharmacological therapy may provide additional clinical benefit over, pharmacological therapy only in patients with severe COPD. Fourty-five patients were randomized in three groups: a group was treated; with IPPB,a group was treated with TPEP and a group with pharmacological; therapy alone (control group). Primary outcome measures included the measurement of scale or, questionnaire concerning dyspnea (MRC scale),dyspnea,cough, and, sputum (BCSS) and quality of life (COPD assessment test) (CAT). Secondary, outcome measures were respiratory function testing,arterial blood gas,analysis,and hematological examinations. Both patients in the IPPB group and in the TPEP group showed a significant, improvement in two of three tests (MRC,CAT) compared to the control, group.However,in the group comparison analysis for, the same variables between IPPB group and TPEP group we observed a, significant improvement in the IPPB group (P≤.05 for MRC and P≤.01 for, CAT). The difference of action of the two techniques are evident in the results of, pulmonary function testing: IPPB increases FVC, FEV1, and MIP; this reflects, its capacity to increase lung volume. Also TPEP increases FVC and FEV1 (less, than IPPB), but increases MEP, while decreasing total lung capacity and, residual volume. The two techniques (IPPB and TPEP) improves significantly dyspnea; quality of; life tools and lung function in patients with severe COPD. IPPB demonstrated a greater effectiveness to improve dyspnea and quality of life tools (MRC, CAT) than TPEP. Copyright © 2013 SEPAR. Published by Elsevier Espana. All rights reserved.

  9. Peripheral chemoreceptors tune inspiratory drive via tonic expiratory neuron hubs in the medullary ventral respiratory column network.

    Science.gov (United States)

    Segers, L S; Nuding, S C; Ott, M M; Dean, J B; Bolser, D C; O'Connor, R; Morris, K F; Lindsey, B G

    2015-01-01

    Models of brain stem ventral respiratory column (VRC) circuits typically emphasize populations of neurons, each active during a particular phase of the respiratory cycle. We have proposed that "tonic" pericolumnar expiratory (t-E) neurons tune breathing during baroreceptor-evoked reductions and central chemoreceptor-evoked enhancements of inspiratory (I) drive. The aims of this study were to further characterize the coordinated activity of t-E neurons and test the hypothesis that peripheral chemoreceptors also modulate drive via inhibition of t-E neurons and disinhibition of their inspiratory neuron targets. Spike trains of 828 VRC neurons were acquired by multielectrode arrays along with phrenic nerve signals from 22 decerebrate, vagotomized, neuromuscularly blocked, artificially ventilated adult cats. Forty-eight of 191 t-E neurons fired synchronously with another t-E neuron as indicated by cross-correlogram central peaks; 32 of the 39 synchronous pairs were elements of groups with mutual pairwise correlations. Gravitational clustering identified fluctuations in t-E neuron synchrony. A network model supported the prediction that inhibitory populations with spike synchrony reduce target neuron firing probabilities, resulting in offset or central correlogram troughs. In five animals, stimulation of carotid chemoreceptors evoked changes in the firing rates of 179 of 240 neurons. Thirty-two neuron pairs had correlogram troughs consistent with convergent and divergent t-E inhibition of I cells and disinhibitory enhancement of drive. Four of 10 t-E neurons that responded to sequential stimulation of peripheral and central chemoreceptors triggered 25 cross-correlograms with offset features. The results support the hypothesis that multiple afferent systems dynamically tune inspiratory drive in part via coordinated t-E neurons. Copyright © 2015 the American Physiological Society.

  10. Elevated tricuspid regurgitant jet velocity, reduced forced expiratory volume in 1 second, and mortality in adults with sickle cell disease.

    Science.gov (United States)

    Chaturvedi, Shruti; Labib Ghafuri, Djamila; Kassim, Adetola; Rodeghier, Mark; DeBaun, Michael R

    2017-02-01

    Cardiopulmonary disease is the leading cause of mortality in adults with sickle cell disease (SCD). Elevated tricuspid regurgitant jet velocity (TRJV) and reduced forced expiratory volume in 1 second (FEV 1 ) %predicted are associated with early mortality in SCD; however their relationship and combined effect on survival is unknown. We investigated the relationship between TRJV and FEV 1 %predicted, and their combined effect on mortality, in a retrospective cohort of 189 adults with SCD who underwent both pulmonary function testing and echocardiography. Nineteen (9.9%) of 189 patients died over a median follow-up of 1.4 years; cardiopulmonary disease was the major cause of death in 52.6%. FEV 1 %predicted was negatively associated with TRJV (Spearman rho, -0.34, P 70% [45.8% versus 17.1%; odds ratio (OR) 4.1 (95% Confidence interval ([CI] 2.1-8.0); P = 0.001]. In a multivariable cox regression model, the combination of TRJV ≥2.5 m/second and FEV 1 %predicted ≤70% predicted earlier mortality [hazard ratio (HR) 4.97 (95% CI 1.30-18.91; P = 0.019)] after adjusting for age, sex, and nephropathy. Both FEV 1 %predicted ≤70% and TRJV ≥2.5 m/second were independently associated with nephropathy [OR 4.48 (95% CI 1.51-13.31); P = 0.004] and [OR 3.27 (95% CI 1.19-9.00); P = 0.017], respectively. In conclusion, pulmonary and cardiac impairment are associated with, and contribute to mortality in SCD. Therapies aimed at improving reduced FEV 1 %predicted and elevated TRJV could improve survival in patients with SCD. Am. J. Hematol. 92:125-130, 2017. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  11. Effects of positive expiratory pressure on pulmonary clearance of aerosolized technetium-99m-labeled diethylenetriaminepentaacetic acid in healthy individuals

    International Nuclear Information System (INIS)

    Albuquerque, Isabella Martins de; Masiero, Paulo Ricardo; Menna-Barreto, Sergio Saldanha; Resqueti, Vanessa Regiane; Fregonezi, Guilherme Augusto de Freitas

    2016-01-01

    Objective: To evaluate the effects of positive expiratory pressure (PEP) on pulmonary epithelial membrane permeability in healthy subjects. Methods: We evaluated a cohort of 30 healthy subjects (15 males and 15 females) with a mean age of 28.3 ± 5.4 years, a mean FEV 1 /FVC ratio of 0.89 ± 0.14, and a mean FEV 1 of 98.5 ± 13.1% of predicted. Subjects underwent technetium-99m labeled diethylenetriaminepentaacetic acid ( 99m TcDTPA) radio aerosol inhalation lung scintigraphy in two stages: during spontaneous breathing; and while breathing through a PEP mask at one of three PEP levels—10 cmH 2 O (n = 10), 15 cmH 2 O (n = 10), and 20 cmH 2 O (n = 10). The 99m Tc-DTPA was nebulized for 3 min, and its clearance was recorded by scintigraphy over a 30-min period during spontaneous breathing and over a 30-min period during breathing through a PEP mask. Results: The pulmonary clearance of 99m Tc-DTPA was significantly shorter when PEP was applied—at 10 cmH 2 O (p = 0.044), 15 cmH 2 O (p = 0.044), and 20 cmH 2 O (p = 0.004) - in comparison with that observed during spontaneous breathing. Conclusions: Our findings indicate that PEP, at the levels tested, is able to induce an increase in pulmonary epithelial membrane permeability and lung volume in healthy subjects. (author)

  12. Differential Effects of Intraoperative Positive End-expiratory Pressure (PEEP) on Respiratory Outcome in Major Abdominal Surgery Versus Craniotomy

    Science.gov (United States)

    Vidal Melo, Marcos F.; Staehr-Rye, Anne Kathrine; Bittner, Edward A.; Kurth, Tobias; Eikermann, Matthias

    2016-01-01

    Objectives In this study, we examined whether (1) positive end-expiratory pressure (PEEP) has a protective effect on the risk of major postoperative respiratory complications in a cohort of patients undergoing major abdominal surgeries and craniotomies, and (2) the effect of PEEP is differed by surgery type. Background Protective mechanical ventilation with lower tidal volumes and PEEP reduces compounded postoperative complications after abdominal surgery. However, data regarding the use of intraoperative PEEP is conflicting. Methods In this observational study, we included 5915 major abdominal surgery patients and 5063 craniotomy patients. Analysis was performed using multivariable logistic regression. The primary outcome was a composite of major postoperative respiratory complications (respiratory failure, reintubation, pulmonary edema, and pneumonia) within 3 days of surgery. Results Within the entire study population (major abdominal surgeries and craniotomies), we found an association between application of PEEP ≥5cmH2O and a decreased risk of postoperative respiratory complications compared with PEEP 5cmH2O was associated with a significant lower odds of respiratory complications in patients undergoing major abdominal surgery (odds ratio 0.53, 95% confidence interval 0.39 – 0.72), effects that translated to deceased hospital length of stay [median hospital length of stay : 6 days (4–9 days), incidence rate ratios for each additional day: 0.91 (0.84 - 0.98)], whereas PEEP >5cmH2O was not significantly associated with reduced odds of respiratory complications or hospital length of stay in patients undergoing craniotomy. Conclusions The protective effects of PEEP are procedure specific with meaningful effects observed in patients undergoing major abdominal surgery. Our data suggest that default mechanical ventilator settings should include PEEP of 5–10cmH2O during major abdominal surgery. PMID:26496082

  13. [A comparative study between inflation and deflation pressure-volume curve in determining the optimal positive end-expiratory pressure].

    Science.gov (United States)

    Gang, Li; Sun, Xiao-yi; Xu, Jin-quan; Zhang, Xin-li; Kou, Lu-xin; Jiang, Zhi-hong; Zhang, Lei

    2012-02-01

    To determine the optimal positive end-expiratory pressure (PEEP) according to inflation and deflation pressure-volume curve (P-V curve) in patients with acute respiratory distress syndrome (ARDS). ARDS models were reproduced in 20 dogs, and they were randomly divided into two groups. In both groups, Levenberg-Marquardt iterative algorithm was employed using software to explore parameters fitting with Boltzmann formula, by which the real inflection point of pressure (Pinf d) in deflation limb or lower inflection point pressure (PLip) in inflation limb on P-V curve were defined. For the control group (inflation curve) P-V curve of PLip + 2 cm H(2)O [1 cm H(2)O = 0.098 kPa] was applied as the best PEEP value. In the experimental group (deflation curve) the Pinf d was taken as the best PEEP value. The heart rate (HR), blood pressure (BP), fingertip pulse oxygen saturation [SpO(2)], static lung compliance (Cst), arterial partial pressure of oxygen [PaO(2)] and arterial partial pressure of carbon dioxide [PaCO(2)] were monitored at 0, 2, 6, 12, 24 and 48 hours. Oxygenation index increased significantly both in control and experimental groups. In experimental group, oxygenation index (mm Hg, 1 mm Hg = 0.133 kPa) of 12, 24 and 48 hours was respectively significantly higher than that of the control group (12 hours: 177.63 ± 8.94 vs. 165.60 ± 8.90, 24 hours: 194.19 ± 10.67 vs. 168.70 ± 10.60, 48 hours: 203.15 ± 13.21 vs. 171.26 ± 9.21, all P deflation P-V curve was better than that of inflation curve.

  14. Validation of a protocol to evaluate maximal expiratory pressure using a pressure transducer and a signal conditioner

    Directory of Open Access Journals (Sweden)

    Viviane Soares

    2011-09-01

    Full Text Available The respiratory muscles can present fatigue and even chronic inability to generate force. So, reliable devices are necessary to their evaluation. The aim of this study is to evaluate the MEP (Maximal Expiratory Pressure values of individuals between 20 and 25 years old and to validate a protocol using a pressure transducer and a signal conditioner comparing it with the digital manometer. We evaluated the MEP of 10 participants. They remained seated and made six respiratory maneuvers from Total Lung Capacity (TLC to Residual Volume (RV. The results in the study showed no statistically significant differences when compared to values reported in the literature, and that the pressure transducer provides reliable values for MEP.Os músculos respiratórios podem apresentar fadiga e até mesmo a incapacidade crônica na geração de força, sendo necessários dispositivos confiáveis para sua avaliação. O objetivo deste estudo foi avaliar a pressão expiratória máxima (PeMáx de indivíduos entre 20 e 25 anos e validar um protocolo que utiliza um transdutor de pressão e um condicionador de sinais comparando-o com a manovacuometria. Foram avaliadas a PeMáx de 10 participantes. Estes permaneceram sentados e realizaram seis manobras respiratórias a partir da capacidade pulmonar total (CPT até o volume residual (VR. Os resultados do estudo não apresentaram diferenças estatisticamente significativas quando comparados com os valores de normalidade descritos na literatura e mostraram que o transdutor de pressão fornece valores confiáveis para Pe máx.

  15. Effects of positive end-expiratory pressure on intraoperative core temperature in patients undergoing posterior spine surgery: prospective randomised trial.

    Science.gov (United States)

    Seo, Hyungseok; Do Son, Je; Lee, Hyung-Chul; Oh, Hyung-Min; Jung, Chul-Woo; Park, Hee-Pyoung

    2018-03-01

    Objective Positive end-expiratory pressure (PEEP) causes carotid baroreceptor unloading, which leads to thermoregulatory peripheral vasoconstriction. However, the effects of PEEP on intraoperative thermoregulation in the prone position remain unknown. Methods Thirty-seven patients undergoing spine surgery in the prone position were assigned at random to receive either 10 cmH 2 O PEEP (Group P) or no PEEP (Group Z). The primary endpoint was core temperature 180 minutes after intubation. Secondary endpoints were delta core temperature (difference in core temperature between 180 minutes and immediately after tracheal intubation), incidence of intraoperative hypothermia (core temperature of peripheral vasoconstriction-related data. Results The median [interquartile range] core temperature 180 minutes after intubation was 36.1°C [35.9°C-36.2°C] and 36.0°C [35.9°C-36.4°C] in Groups Z and P, respectively. The delta core temperature and incidences of intraoperative hypothermia and peripheral vasoconstriction were not significantly different between the two groups. The peripheral vasoconstriction threshold (36.2°C±0.5°C vs. 36.7°C±0.6°C) was lower and the onset of peripheral vasoconstriction (66 [60-129] vs. 38 [28-70] minutes) was slower in Group Z than in Group P. Conclusions Intraoperative PEEP did not reduce the core temperature decrease in the prone position, although it resulted in an earlier onset and higher threshold of peripheral vasoconstriction.

  16. Effects of positive end-expiratory pressure on mechanical ventilation duration after coronary artery bypass grafting: a randomized clinical trial.

    Science.gov (United States)

    Lago Borges, Daniel; José da Silva Nina, Vinícius; Pereira Baldez, Thiago Eduardo; de Albuquerque Gonçalves Costa, Marina; Pereira dos Santos, Natália; Mendes Lima, Ilka; Lima da Silva Lula, Josimary

    2014-01-01

    Patients undergoing cardiac surgery remain on mechanical ventilation postoperatively until they regain consciousness. Positive end-expiratory pressure (PEEP) may influence the duration of mechanical ventilation after coronary artery bypass grafting (CABG). The aim of this study was to compare the effects of different levels of PEEP on the duration of mechanical ventilation after coronary artery bypass grafting. This was a randomized clinical trial with 136 patients undergoing CABG between January 2011 and March 2012. We divided the patients into three groups with different levels of PEEP at the onset of mechanical ventilation: Group A, PEEP=5 cmH2O (n=44); Group B, PEEP=8 cmH2O (n=47) and Group C, PEEP=10 cmH2O (n=45). Mechanical ventilation time was obtained from a Physical Therapy Evaluation Form. We excluded patients with chronic obstructive pulmonary disease and those requiring concomitant, emergency or off-pump surgeries. For statistical analysis, we used the Kruskal-Wallis, G and Chi-square tests, with pweaning from mechanical ventilation until 12 hours after intensive care unit (ICU) admission, we saw a statistically different duration of mechanical ventilation between groups (p=0.029). In Group A, the average mechanical ventilation time was 6.7±3.2 hours; it was 6.8±3.3 hours in Group B and 5.1±2.9 hours in Group C. The use of higher levels of PEEP was associated with shorter duration of mechanical ventilation in postoperative CABG patients.

  17. Flow regime analysis of non-Newtonian duct flows

    Science.gov (United States)

    Speetjens, Michel; Rudman, Murray; Metcalfe, Guy

    2006-01-01

    Reoriented duct flows of generalized Newtonian fluids are an idealization of non-Newtonian fluid flow in industrial in-line mixers. Based on scaling analysis and computation we find that non-Newtonian duct flows have several limit behaviors, in the sense that such flows can become (nearly) independent of one or more of the rheological and dynamical control parameters, simplifying the general flow and mixing problem. These limit flows give several levels of modeling complexity to the full problem of non-Newtonian duct flow. We describe the sets of simplified flow models and their corresponding regions of validity. This flow-model decomposition captures the essential rheological and dynamical characteristics of the reoriented duct flows and enables a more efficient and systematic study and design of flow and mixing of non-Newtonian fluids in ducts. Key aspects of the flow-model decomposition are demonstrated via a specific, but representative, duct flow.

  18. Angle β of greater than 80° at the start of spirometry may identify high-quality flow volume curves.

    Science.gov (United States)

    Lian, Ningfang; Li, Li; Ren, Weiying; Jiang, Zhilong; Zhu, Lei

    2017-04-01

    The American Thoracic Society (ATS) and European Respiratory Society (ERS) emphasize a satisfactory start in maximal expiratory flow-volume (MEFV) curves and highlight subjective parameters: performance without hesitation and expiration with maximum force. We described a new parameter, angle β for characterization of the start to the MEFV curve. Subjects completed the MEFV curve at least three times and at least two curves met ATS/ERS quality. Subjects were divided into normal, restrictive and obstructive groups according to pulmonary function test results. The tangent line was drawn at the start of the MEFV curve's ascending limb to the x-axis and the angle β between the tangent line and x-axis was obtained. The relationships between tangent of β, pulmonary function parameters (PFPs) and anthropometric data were assessed. The MEFV curves with insufficient explosion at the start were considered as poor-quality MEFV curves. In 998 subjects with high-quality spirometry, although PFP varied in relation to the three aspects: the angle β and its tangent were similar (P > 0.05), the tangent of β did not correlate with PFP or anthropometric measurements (P > 0.05) and the lower limit of normal (LLN) of the angle β was 80° in the group with high-quality spirometry (P < 0.05). Angle β derived from poor-quality MEFV curves was smaller than that from good quality one (P < 0.05). Angle β may function as a parameter to assess the expiratory efforts, which can be used to assess the quality of the MEFV curve start. © 2016 Asian Pacific Society of Respirology.

  19. Clinical evidence on high flow oxygen therapy and active humidification in adults.

    Science.gov (United States)

    Gotera, C; Díaz Lobato, S; Pinto, T; Winck, J C

    2013-01-01

    Recently there has been growing interest in an alternative to conventional oxygen therapy: the heated, humidified high flow nasal cannula oxygen therapy (HFNC). A number of physiological effects have been described with HFNC: pharyngeal dead space washout, reduction of nasopharyngeal resistance, a positive expiratory pressure effect, an alveolar recruitment, greater humidification, more comfort and better tolerance by the patient, better control of FiO2 and mucociliary clearance. There is limited experience of HFNC in adults. There are no established guidelines or decision-making pathways to guide use of the HFNC therapy for adults. In this article we review the existing evidence of HFNC oxygen therapy in adult patients, its advantages, limitations and the current literature on clinical applications. Further research is required to determine the long-term effect of this therapy and identify the adult patient population to whom it is most beneficial. Copyright © 2013 Sociedade Portuguesa de Pneumologia. Published by Elsevier España. All rights reserved.

  20. Ventilator flow data predict bronchopulmonary dysplasia in extremely premature neonates

    Directory of Open Access Journals (Sweden)

    Mariann H. Bentsen

    2018-03-01

    Full Text Available Early prediction of bronchopulmonary dysplasia (BPD may facilitate tailored management for neonates at risk. We investigated whether easily accessible flow data from a mechanical ventilator can predict BPD in neonates born extremely premature (EP. In a prospective population-based study of EP-born neonates, flow data were obtained from the ventilator during the first 48 h of life. Data were logged for >10 min and then converted to flow–volume loops using custom-made software. Tidal breathing parameters were calculated and averaged from ≥200 breath cycles, and data were compared between those who later developed moderate/severe and no/mild BPD. Of 33 neonates, 18 developed moderate/severe and 15 no/mild BPD. The groups did not differ in gestational age, surfactant treatment or ventilator settings. The infants who developed moderate/severe BPD had evidence of less airflow obstruction, significantly so for tidal expiratory flow at 50% of tidal expiratory volume (TEF50 expressed as a ratio of peak tidal expiratory flow (PTEF (p=0.007. A compound model estimated by multiple logistic regression incorporating TEF50/PTEF, birthweight z-score and sex predicted moderate/severe BPD with good accuracy (area under the curve 0.893, 95% CI 0.735–0.973. This study suggests that flow data obtained from ventilators during the first hours of life may predict later BPD in premature neonates. Future and larger studies are needed to validate these findings and to determine their clinical usefulness.

  1. Positive end-expiratory pressure improves survival in a rodent model of cardiopulmonary resuscitation using high-dose epinephrine.

    Science.gov (United States)

    McCaul, Conán; Kornecki, Alik; Engelberts, Doreen; McNamara, Patrick; Kavanagh, Brian P

    2009-10-01

    Multiple interventions have been tested in models of cardiopulmonary resuscitation (CPR) to optimize drug use, chest compressions, and ventilation. None has studied the effects of positive end-expiratory pressure (PEEP) on outcome. We hypothesized that because PEEP can reverse pulmonary atelectasis, lower pulmonary vascular resistance, and potentially improve cardiac output, its use during CPR would increase survival. Anesthetized Sprague-Dawley rats were exposed to 1 min of asphyxial cardiac arrest. Resuscitation was standardized and consisted of chest compressions, oxygen (Fio(2) 1.0), and IV epinephrine 30 microg/kg (Series 1) and 10 microg/kg (Series 2). Left ventricular function was assessed by echocardiography (Series 1), and animals were randomized to receive either 5 cm H(2)O PEEP or zero PEEP at commencement of CPR and throughout resuscitation. Survival was defined as the presence of a spontaneous circulation 60 or 120 min (Series 2) after initial resuscitation. There were no baseline differences between the groups. In Series 1, administration of 5 cm H(2)O PEEP (Fio(2) 1.0 and 0.21) was associated with improved survival compared with zero PEEP (7/9 and 6/6 vs 0/9, P CPR did not adversely affect left ventricular systolic function or arterial blood pressure. The outcome differences were not due to increased oxygenation because the rank order of survival was 5 cm H(2)O PEEP (Fio(2) 1.0) approximately 5 cm H(2)O PEEP (Fio(2) 0.21) > zero PEEP (Fio(2) 1.0), whereas the rank order of Pao(2) was 5 cm H(2)O PEEP (Fio(2) 1.0) > 5 cm H(2)O PEEP (Fio(2) 0.21) approximately zero PEEP (Fio(2) 1.0). In an additional series in which epinephrine 10 microg/kg was used (Series 2), the survival was 100% with no beneficial effects of PEEP. In asphyxial cardiac arrest in a small rodent model, continuous application of PEEP (5 cm H(2)O) during and after CPR had beneficial effects on survival that were independent of oxygenation and without adverse cardiovascular effects.

  2. Current limiter circuit system

    Energy Technology Data Exchange (ETDEWEB)

    Witcher, Joseph Brandon; Bredemann, Michael V.

    2017-09-05

    An apparatus comprising a steady state sensing circuit, a switching circuit, and a detection circuit. The steady state sensing circuit is connected to a first, a second and a third node. The first node is connected to a first device, the second node is connected to a second device, and the steady state sensing circuit causes a scaled current to flow at the third node. The scaled current is proportional to a voltage difference between the first and second node. The switching circuit limits an amount of current that flows between the first and second device. The detection circuit is connected to the third node and the switching circuit. The detection circuit monitors the scaled current at the third node and controls the switching circuit to limit the amount of the current that flows between the first and second device when the scaled current is greater than a desired level.

  3. Diversity in photosynthetic electron transport under [CO2]-limitation: the cyanobacterium Synechococcus sp. PCC 7002 and green alga Chlamydomonas reinhardtii drive an O2-dependent alternative electron flow and non-photochemical quenching of chlorophyll fluorescence during CO2-limited photosynthesis.

    Science.gov (United States)

    Shimakawa, Ginga; Akimoto, Seiji; Ueno, Yoshifumi; Wada, Ayumi; Shaku, Keiichiro; Takahashi, Yuichiro; Miyake, Chikahiro

    2016-12-01

    Some cyanobacteria, but not all, experience an induction of alternative electron flow (AEF) during CO 2 -limited photosynthesis. For example, Synechocystis sp. PCC 6803 (S. 6803) exhibits AEF, but Synechococcus elongatus sp. PCC 7942 does not. This difference is due to the presence of flavodiiron 2 and 4 proteins (FLV2/4) in S. 6803, which catalyze electron donation to O 2 . In this study, we observed a low-[CO 2 ] induced AEF in the marine cyanobacterium Synechococcus sp. PCC 7002 that lacks FLV2/4. The AEF shows high affinity for O 2 , compared with AEF mediated by FLV2/4 in S. 6803, and can proceed under extreme low [O 2 ] (about a few µM O 2 ). Further, the transition from CO 2 -saturated to CO 2 -limited photosynthesis leads a preferential excitation of PSI to PSII and increased non-photochemical quenching of chlorophyll fluorescence. We found that the model green alga Chlamydomonas reinhardtii also has an O 2 -dependent AEF showing the same affinity for O 2 as that in S. 7002. These data represent the diverse molecular mechanisms to drive AEF in cyanobacteria and green algae. In this paper, we further discuss the diversity, the evolution, and the physiological function of strategy to CO 2 -limitation in cyanobacterial and green algal photosynthesis.

  4. Effect of expiratory muscle strength training on swallowing-related muscle strength in community-dwelling elderly individuals: a randomized controlled trial.

    Science.gov (United States)

    Park, Ji-Su; Oh, Dong-Hwan; Chang, Moon-Young

    2017-03-01

    This study aimed to investigate the effect of expiratory muscle strength training (EMST) on swallowing-related muscle strength in community-dwelling elderly individuals. Expiratory muscle strength training is an intervention for patients with oropharyngeal dysphagia. This training is associated with respiration, coughing, speech and swallowing, and its effectiveness has been proven in previous studies. However, the effects of EMST on elderly individuals and evidence are still lacking. This study included 24 community-dwelling senior citizens aged ≥65 years (12 men and 12 women). The experimental group trained at the 70% threshold value of the maximum expiratory pressure using an EMST device 5 days per week for 4 weeks and comprised five sets of five breaths through the device for 25 breaths per day. The placebo group trained with a resistance-free sham device. Post-intervention, muscle strength of the bilateral buccinator and the orbicularis oris muscles (OOM) was measured using the Iowa Oral Performance Instrument. Surface electromyography was used to measure activation of the suprahyoid muscles (SM). After intervention, the strength of the buccinator and the OOM in the experimental group showed statistically significant improvement. There was also statistically significant activation of the SM. In the placebo group, the strength of the orbicularis oris muscle alone improved. No statistically significant differences between groups were found for the strength of the buccinator and the OOM and the activation of the SM. EMST had a positive effect on swallowing-related muscle strength in elderly participants. © 2016 John Wiley & Sons A/S and The Gerodontology Association. Published by John Wiley & Sons Ltd.

  5. Safety and effectiveness of alveolar recruitment maneuvers and positive end-expiratory pressure during general anesthesia for cesarean section: a prospective, randomized trial.

    Science.gov (United States)

    Aretha, D; Fligou, F; Kiekkas, P; Messini, C; Panteli, E; Zintzaras, E; Karanikolas, M

    2017-05-01

    During cesarean section, the supine position reduces functional residual capacity and worsens lung compliance. We tested the hypothesis that alveolar recruitment maneuvers and positive end-expiratory pressure improve lung compliance in women undergoing general anesthesia for cesarean section. Ninety women undergoing cesarean section were randomly assigned to one of two groups in a prospective, double-blind trial. In the alveolar recruitment maneuver group, pressure-control ventilation was used and inspiratory time was increased to 50% after delivery; positive end-expiratory pressure was increased to 20cmH 2 O and peak airway inspiratory pressure gradually increased to 45-50cmH 2 O. Volume-control ventilation was then used with low tidal volumes (6mL/kg) and positive end-expiratory pressure was reduced stepwise to 8cmH 2 O. In the control group, alveolar recruitment maneuvers were not used. Data were collected before and 3, 10 and 20min after the alveolar recruitment maneuver, before extubation and postoperatively at 10 and 20min. Dynamic compliance, peak airway inspiratory pressure, PaO 2 and PaO 2 /FiO 2 were significantly different in the alveolar recruitment maneuver group compared to controls at all time points during surgery except at baseline. Oxygen saturation was significantly greater in the alveolar recruitment maneuver group at 10 and 20min and before extubation. Dynamic compliance was 29.7-42.5% higher and peak airway inspiratory pressure 3.6-10.2% lower in the alveolar recruitment maneuver group compared to controls. The PaO 2 , PaO 2 /FiO 2 and oxygen saturation were higher (9.4-12%, 10.3-11.9% and 0.4-1.3%, respectively) in the alveolar recruitment maneuver group. Postoperatively, PaO 2 and oxygen saturation were significantly higher in the alveolar recruitment maneuver group compared to controls (PaO 2 9.2% at 10min and 8.4% at 20min, oxygen saturation 0.8% at 10min and 1.1% at 20min). There were no significant differences in hemodynamic stability or

  6. Flow Rounding

    OpenAIRE

    Kang, Donggu; Payor, James

    2015-01-01

    We consider flow rounding: finding an integral flow from a fractional flow. Costed flow rounding asks that we find an integral flow with no worse cost. Randomized flow rounding requires we randomly find an integral flow such that the expected flow along each edge matches the fractional flow. Both problems are reduced to cycle canceling, for which we develop an $O(m \\log(n^2/m))$ algorithm.

  7. Quench limits

    International Nuclear Information System (INIS)

    Sapinski, M.

    2012-01-01

    With thirteen beam induced quenches and numerous Machine Development tests, the current knowledge of LHC magnets quench limits still contains a lot of unknowns. Various approaches to determine the quench limits are reviewed and results of the tests are presented. Attempt to reconstruct a coherent picture emerging from these results is taken. The available methods of computation of the quench levels are presented together with dedicated particle shower simulations which are necessary to understand the tests. The future experiments, needed to reach better understanding of quench limits as well as limits for the machine operation are investigated. The possible strategies to set BLM (Beam Loss Monitor) thresholds are discussed. (author)

  8. Dose limits

    International Nuclear Information System (INIS)

    Fitoussi, L.

    1987-12-01

    The dose limit is defined to be the level of harmfulness which must not be exceeded, so that an activity can be exercised in a regular manner without running a risk unacceptable to man and the society. The paper examines the effects of radiation categorised into stochastic and non-stochastic. Dose limits for workers and the public are discussed

  9. Comparison of pulmonary function in patients with COPD, asthma-COPD overlap syndrome, and asthma with airflow limitation

    Directory of Open Access Journals (Sweden)

    Kitaguchi Y

    2016-05-01

    Full Text Available Yoshiaki Kitaguchi, Masanori Yasuo, Masayuki Hanaoka First Department of Internal Medicine, Shinshu University School of Medicine, Matsumoto, Japan Background: This study was conducted in order to investigate the differences in the respiratory physiology of patients with chronic obstructive pulmonary disease (COPD, asthma-COPD overlap syndrome (ACOS, and asthma with airflow limitation (asthma FL+. Methods: The medical records for a series of all stable patients with persistent airflow limitation due to COPD, ACOS, or asthma were retrospectively reviewed and divided into the COPD group (n=118, the ACOS group (n=32, and the asthma FL+ group (n=27. All the patients underwent chest high-resolution computed tomography (HRCT and pulmonary function tests, including respiratory impedance. Results: The low attenuation area score on chest HRCT was significantly higher in the COPD group than in the ACOS group (9.52±0.76 vs 5.09±1.16, P<0.01. The prevalence of bronchial wall thickening on chest HRCT was significantly higher in the asthma FL+ group than in the COPD group (55.6% vs 25.0%, P<0.01. In pulmonary function, forced expiratory volume in 1 second (FEV1 and peak expiratory flow rate were significantly higher in the asthma FL+ group than in the ACOS group (76.28%±2.54% predicted vs 63.43%±3.22% predicted, P<0.05 and 74.40%±3.16% predicted vs 61.08%±3.54% predicted, P<0.05, respectively. Although residual volume was significantly lower in the asthma FL+ group than in the COPD group (112.05%±4.34% predicted vs 137.38%±3.43% predicted, P<0.01 and the ACOS group (112.05%±4.34% predicted vs148.46%±6.25% predicted, P<0.01, there were no significant differences in functional residual capacity or total lung capacity. The increase in FEV1 in response to short-acting ß2-agonists was significantly greater in the ACOS group than in the COPD group (229±29 mL vs 72±10 mL, P<0.01 and the asthma FL+ group (229±29 mL vs 153±21 mL, P<0.05. Regarding

  10. Comparison of pulmonary function in patients with COPD, asthma-COPD overlap syndrome, and asthma with airflow limitation.

    Science.gov (United States)

    Kitaguchi, Yoshiaki; Yasuo, Masanori; Hanaoka, Masayuki

    2016-01-01

    This study was conducted in order to investigate the differences in the respiratory physiology of patients with chronic obstructive pulmonary disease (COPD), asthma-COPD overlap syndrome (ACOS), and asthma with airflow limitation (asthma FL(+)). The medical records for a series of all stable patients with persistent airflow limitation due to COPD, ACOS, or asthma were retrospectively reviewed and divided into the COPD group (n=118), the ACOS group (n=32), and the asthma FL(+) group (n=27). All the patients underwent chest high-resolution computed tomography (HRCT) and pulmonary function tests, including respiratory impedance. The low attenuation area score on chest HRCT was significantly higher in the COPD group than in the ACOS group (9.52±0.76 vs 5.09±1.16, Pbronchial wall thickening on chest HRCT was significantly higher in the asthma FL(+) group than in the COPD group (55.6% vs 25.0%, P<0.01). In pulmonary function, forced expiratory volume in 1 second (FEV1) and peak expiratory flow rate were significantly higher in the asthma FL(+) group than in the ACOS group (76.28%±2.54% predicted vs 63.43%±3.22% predicted, P<0.05 and 74.40%±3.16% predicted vs 61.08%±3.54% predicted, P<0.05, respectively). Although residual volume was significantly lower in the asthma FL(+) group than in the COPD group (112.05%±4.34% predicted vs 137.38%±3.43% predicted, P<0.01) and the ACOS group (112.05%±4.34% predicted vs148.46%±6.25% predicted, P<0.01), there were no significant differences in functional residual capacity or total lung capacity. The increase in FEV1 in response to short-acting β2-agonists was significantly greater in the ACOS group than in the COPD group (229±29 mL vs 72±10 mL, P<0.01) and the asthma FL(+) group (229±29 mL vs 153±21 mL, P<0.05). Regarding respiratory impedance, resistance at 5 Hz and resistance at 20 Hz, which are oscillatory parameters of respiratory resistance, were significantly higher in the asthma FL(+) group than in the COPD group

  11. Effects of Hemibridge with Ball and Balloon Exercise on Forced Expiratory Volume and Pain in Patients with Chronic Low Back Pain: An Experimental Study

    Directory of Open Access Journals (Sweden)

    Jorida Fernandes

    2017-08-01

    Full Text Available Background and objectives: Suboptimal breathing patterns and impairments of posture and trunk stability are often associated with musculoskeletal complaints such as low back pain. Respiration is also affected by poor neuromuscular control of core muscles. Immediate effects of hemibridge with ball and balloon exercise has been studied on chronic pain in athlete population. Objective: To evaluate the effects of hemibridge with ball and balloon exercise on pain, forced expiratory volume and functional abilities in patients with chronic low back pain using Visual Analogue Scale (VAS, Forced Expiratory Volume (FEV and Modified Oswestry Disability Questionnaire (MODQ. Methods: The present experimental study was conducted among 30 participants between the age of 21 to 55 years with chronic non-specific LBP. The participants were given a hemibridge with ball and balloon exercise. Pre-interventional and 3rd day Post-interventional outcome measurements were taken using VAS, FEV1 and FEV6 and MODQ. Results: The difference between pre-and post of VAS was statistically highly significant (p=0.0001. The p value of FEV6 and MODQ by paired t test was statistically significant with p value of 0.02 and 0.0007 respectively. Conclusion: The study concludes that there is an immediate effect of hemibridge with ball and balloon exercise on pain, FEV6 and functional ability in patients with chronic LBP.

  12. [POSITIVE END-EXPIRATORY PRESSURE (PEEP) INFLUENCES ON INTRACRANIAL PRESSURE, SYSTEMIC HEMODYNAMICS AND PULMONARY GAS EXCHANGE IN PATIENTS WITH INTRACRANIAl HEMORRHAGE IN CRITICAL STATE].

    Science.gov (United States)

    Solodov, A A; Petrikov, S S; Krylov, V V

    2016-01-01

    Positive end-expiratory pressure is one of the main parameters of respiratory support influencing the gas exchange. However, despite the number ofpositive effects, PEEP can compromise venous outflow from the cranial cavity, increased intracranial pressure, decreased venous return and cardiac output and, consequently, reduced blood pressure and cerebral perfusion. The article presents the results of a survey of 39 patients with intracranial hemorrhage in critical state, undergoing respiratory support with different levels of positive end-expiratory pressure. Increasing of PEEP to 15 cm H2O had no adverse effect on mean arterial pressure, heart rate and cerebral perfusion pressure and led only to an clinical insignificant increase (maximum on 2.4 +/- 5.1 mmHg) in intracranial pressure. The greatest hemodynamic changes were observed with increasing PEEP up to 20 cm H2O in patients with preserved compliance ofthe respiratory system. The instability of cerebral perfusion and intracranial pressure associated with a decrease in cardiac output and preload and the exhaustion of compensatory mechanism of peripheral vascular resistance. High levels of PEEP despite the trend towards Cstat reduction will not lead to an increase in the content of extravascular lung water Thus a gradual increase of PEEP to 15 cm H2O can be safe and effective method of improving pulmonary gas exchange in patients with intracranial hemorrhage in critical state.

  13. Expiratory activation of abdominal muscle is associated with improved respiratory stability and an increase in minute ventilation in REM epochs of adult rats.

    Science.gov (United States)

    Andrews, Colin G; Pagliardini, Silvia

    2015-11-01

    Breathing is more vulnerable to apneas and irregular breathing patterns during rapid eye movement (REM) sleep in both humans and rodents. We previously reported that robust and recurrent recruitment of expiratory abdominal (ABD) muscle activity is present in rats during REM epochs despite ongoing REM-induced muscle atonia in skeletal musculature. To develop a further understanding of the characteristics of ABD recruitment during REM epochs and their relationship with breathing patterns and irregularities, we sought to compare REM epochs that displayed ABD muscle recruitment with those that did not, within the same rats. Specifically, we investigated respiratory characteristics that preceded and followed recruitment. We hypothesized that ABD muscle recruitment would be likely to occur following respiratory irregularities and would subsequently contribute to respiratory stability and the maintenance of good ventilation following recruitment. Our data demonstrate that epochs of REM sleep containing ABD recruitments (REM(ABD+)) were characterized by increased respiratory rate variability and increased presence of spontaneous brief central apneas. Within these epochs, respiratory events that displayed ABD muscle activation were preceded by periods of increased respiratory rate variability. Onset of ABD muscle activity increased tidal volume, amplitude of diaphragmatic contractions, and minute ventilation compared with the periods preceding ABD muscle activation. These results show that expiratory muscle activity is more likely recruited when respiration is irregular and its recruitment is subsequently associated with an increase in minute ventilation and a more regular respiratory rhythm. Copyright © 2015 the American Physiological Society.

  14. Inverse Limits

    CERN Document Server

    Ingram, WT

    2012-01-01

    Inverse limits provide a powerful tool for constructing complicated spaces from simple ones. They also turn the study of a dynamical system consisting of a space and a self-map into a study of a (likely more complicated) space and a self-homeomorphism. In four chapters along with an appendix containing background material the authors develop the theory of inverse limits. The book begins with an introduction through inverse limits on [0,1] before moving to a general treatment of the subject. Special topics in continuum theory complete the book. Although it is not a book on dynamics, the influen

  15. Pressures delivered by nasal high flow oxygen during all phases of the respiratory cycle.

    Science.gov (United States)

    Parke, Rachael L; McGuinness, Shay P

    2013-10-01

    Nasal high flow (NHF) oxygen therapy and CPAP are modes of noninvasive respiratory support used to improve respiratory function in multiple patient groups. Both therapies provide positive pressure, although this varies during the respiratory cycle. The purpose of this study was to measure and compare the airway pressure generated during different phases of the respiratory cycle in patients receiving NHF at various gas flows. Patients scheduled for elective cardiac surgery were invited to participate. Nasopharyngeal pressure measurements were performed using NHF with gas flows of 30, 40, and 50 L/min. All measurements were performed in random order, with the subject breathing with mouth closed. During NHF the mean ± SD nasopharyngeal airway pressures were 1.5 ± 0.6, 2.2 ± 0.8, and 3.1 ± 1.2 at 30, 40, and 50 L/min using NHF. Analyses also determined the mean peak expiratory and mean expiratory plateau pressures. The expiratory pressure during NHF was higher than the mean pressure previously reported for NHF. This may account in part for the disproportional clinical effects seen with NHF. (Australian Clinical Trials Registry www.anzctr.org.au ACTRN12609000305224).

  16. The Control of Junction Flows

    National Research Council Canada - National Science Library

    Smith, Charles

    1997-01-01

    An experimental study of the effects of spatially-limited (i.e. localized) surface suction on unsteady laminar and turbulent junction flows was performed using hydrogen bubble flow visualization and Particle Image Velocimetry (PIV...

  17. Passive leg-raising and end-expiratory occlusion tests perform better than pulse pressure variation in patients with low respiratory system compliance.

    Science.gov (United States)

    Monnet, Xavier; Bleibtreu, Alexandre; Ferré, Alexis; Dres, Martin; Gharbi, Rim; Richard, Christian; Teboul, Jean-Louis

    2012-01-01

    We tested whether the poor ability of pulse pressure variation to predict fluid responsiveness in cases of acute respiratory distress syndrome was related to low lung compliance. We also tested whether the changes in cardiac index induced by passive leg-raising and by an end-expiratory occlusion test were better than pulse pressure variation at predicting fluid responsiveness in acute respiratory distress syndrome patients. Prospective study. Medical intensive care unit. We included 54 patients with circulatory shock (63 ± 13 yrs; Simplified Acute Physiology Score II, 63 ± 24). Twenty-seven patients had acute respiratory distress syndrome (compliance of the respiratory system, 22 ± 3 mL/cm H2O). In nonacute respiratory distress syndrome patients, the compliance of the respiratory system was 45 ± 9 mL/cm H2O. We measured the response of cardiac index (transpulmonary thermodilution) to fluid administration (500 mL saline). Before fluid administration, we recorded pulse pressure variation and the changes in pulse contour analysis-derived cardiac index induced by passive leg-raising and end-expiratory occlusion. Fluid increased cardiac index ≥ 15% (44% ± 39%) in 30 "responders." Pulse pressure variation was significantly correlated with compliance of the respiratory system (r = .58), but not with tidal volume. The higher the compliance of the respiratory system, the better the prediction of fluid responsiveness by pulse pressure variation. A compliance of the respiratory system of 30 mL/cm H2O was the best cut-off for discriminating patients regarding the ability of pulse pressure variation to predict fluid responsiveness. If compliance of the respiratory system was >30 mL/cm H2O, then the area under the receiver-operating characteristics curve for predicting fluid responsiveness was not different for pulse pressure variation and the passive leg-raising and end-expiratory occlusion tests (0.98 ± 0.03, 0.91 ± 0.06, and 0.97 ± 0.03, respectively). By contrast

  18. Ajuste de las simulaciones de flujos continuados para el cálculo del Límite de Potencia Eólica; Calculation of Wind Power Limit adjusting the Continuation Power Flow

    Directory of Open Access Journals (Sweden)

    Ariel Santos Fuentefria

    2012-07-01

    Full Text Available La integración de la energía eólica en los sistemas eléctricos puede provocar problemas de estabilidad ligados fundamentalmente a la variación aleatoria del viento y que se reflejan en la tensión y la frecuencia del sistema. Por lo que conocer el Límite de Potencia Eólica (LPE que puede insertarse en la red sin que esta pierda la estabilidad es un aspecto de extrema importancia, en el cual se han realizando métodos de cálculo para encontrar dicho límite. Estos métodos se desarrollan teniendo en cuenta las restricciones del sistema en estado estacionario, en estado dinámico o ambos. En el siguiente trabajo se desarrolla un método para el cálculo de LPE teniendo en cuenta las restricciones en estado estacionario del sistema. El método propuesto se basa en un análisis de flujo continuado, complementado con el método de Producción Mínima de Potencia Activa, desarrollado en la bibliografía. Se prueba en el sistema eléctrico de la Isla de la Juventud, Cuba y se usa elsoftware libre PSAT para la realización de estos estudios.  The wind power insertion in the power system is an important issue and can create some instability problems in voltage and system frequency due to stochastic origin of wind. Know the Wind Power Limit is a very importantmatter. Existing In bibliography a few methods for calculation of wind power limit. The calculation is based in static constrains, dynamic constraints or both. In this paper is developed a method for the calculation of wind power limit using some adjust in the continuation power flow, and having into account the static constrains. The method is complemented with Minimal Power Production Criterion. The method is proved in the Isla de la Juventud Electric System. The software used in the simulations was the Power System Analysis Toolbox (PSAT.

  19. Effects of equipment and technique on peak flow measurements

    Directory of Open Access Journals (Sweden)

    O'Driscoll B Ronan

    2006-06-01

    Full Text Available Abstract Background Different lung function equipment and different respiratory manoeuvres may produce different Peak Expiratory Flow (PEF results. Although the PEF is the most common lung function test, there have been few studies of these effects and no previous study has evaluated both factors in a single group of patients. Methods We studied 36 subjects (PEF range 80–570 l/min. All patients recorded PEF measurements using a short rapid expiration following maximal inspiration (PEF technique or a forced maximal expiration to residual volume (FVC technique. Measurements were made using a Wright's peak flow meter, a turbine spirometer and a Fleisch pneumotachograph spirometer. Results The mean PEF was 8.7% higher when the PEF technique was used (compared with FVC technique, p Conclusion Peak flow measurements are affected by the instruction given and by the device and Peak Flow scale used. Patient management decisions should not be based on PEF measurement made on different instruments.

  20. Changes in Cross-Sectional Area and Transverse Diameter of the Heart on Inspiratory and Expiratory Chest CT: Correlation with Changes in Lung Size and Influence on Cardiothoracic Ratio Measurement.

    Directory of Open Access Journals (Sweden)

    Hayato Tomita

    Full Text Available The aim of this study was to investigate physiological changes in cardiac area and diameters between inspiratory and expiratory chest computed tomography (CT, and to assess their correlation with lung size change and influence on cardiothoracic ratio (CTR measurements.The institutional review board of our institution approved this study, and informed consent was waived. Forty-three subjects underwent inspiratory and expiratory chest CT as part of routine clinical care. On both inspiratory and expiratory scans, lung volumes and maximum lung diameters (transverse and vertical directions were measured. The maximum cardiac cross-sectional area (CSA and the maximum transverse cardiac diameter were measured on both scans, and the CT-based CTR was calculated. Changes in the lung and cardiac measurements were expressed as the expiratory/inspiratory (E/I ratios. Comparisons between inspiratory and expiratory measurements were made by the Wilcoxon signed-rank test. Correlations between the E/I ratios of lung and heart measurements were evaluated by Spearman's rank correlation analysis.Cardiac CSA and transverse cardiac diameter was significantly larger on expiratory than on inspiratory CT (p < 0.0001. Significant negative correlations were found between the E/I ratios of these cardiac measurements and the E/I ratios of lung volume and vertical lung diameter (p < 0.01. CT-based CTR was significantly larger on expiration than on inspiration (p < 0.0001.Heart size on chest CT depends on the phase of ventilation, and is correlated with changes in lung volume and craniocaudal lung diameter. The CTR is also significantly influenced by ventilation.

  1. Combined coronary angiography and myocardial perfusion by computed tomography in the identification of flow-limiting stenosis - The CORE320 study: An integrated analysis of CT coronary angiography and myocardial perfusion.

    Science.gov (United States)

    Magalhães, Tiago A; Kishi, Satoru; George, Richard T; Arbab-Zadeh, Armin; Vavere, Andrea L; Cox, Christopher; Matheson, Matthew B; Miller, Julie M; Brinker, Jeffrey; Di Carli, Marcelo; Rybicki, Frank J; Rochitte, Carlos E; Clouse, Melvin E; Lima, João A C

    2015-01-01

    The combination of coronary CT angiography (CTA) and myocardial CT perfusion (CTP) is gaining increasing acceptance, but a standardized approach to be implemented in the clinical setting is necessary. To investigate the accuracy of a combined coronary CTA and myocardial CTP comprehensive protocol compared to coronary CTA alone, using a combination of invasive coronary angiography and single photon emission CT as reference. Three hundred eighty-one patients included in the CORE320 trial were analyzed in this study. Flow-limiting stenosis was defined as the presence of ≥50% stenosis by invasive coronary angiography with a related perfusion defect by single photon emission CT. The combined CTA + CTP definition of disease was the presence of a ≥50% stenosis with a related perfusion defect. All data sets were analyzed by 2 experienced readers, aligning anatomic findings by CTA with perfusion defects by CTP. Mean patient age was 62 ± 6 years (66% male), 27% with prior history of myocardial infarction. In a per-patient analysis, sensitivity for CTA alone was 93%, specificity was 54%, positive predictive value was 55%, negative predictive value was 93%, and overall accuracy was 69%. After combining CTA and CTP, sensitivity was 78%, specificity was 73%, negative predictive value was 64%, positive predictive value was 0.85%, and overall accuracy was 75%. In a per-vessel analysis, overall accuracy of CTA alone was 73% compared to 79% for the combination of CTA and CTP (P perfusion defect. Copyright © 2015 Society of Cardiovascular Computed Tomography. Published by Elsevier Inc. All rights reserved.

  2. Sensitivity and specificity of hypopnoea detection using nasal pressure in the presence of a nasal expiratory resistive device (Provent®)

    International Nuclear Information System (INIS)

    Milne, Stephen; Amis, Terence C; Wheatley, John R; Kairaitis, Kristina

    2014-01-01

    Nasal expiratory resistive valves (Provent ® ) have been proposed as novel therapy for obstructive sleep apnea. We compared pressure measurements from a standard nasal pressure catheter used to assess nasal airflow during sleep with those from nasal expiratory resistive device with attached proprietary nasal pressure cannula. Nasal pressure cannula or Provent ® + proprietary nasal pressure cannula were attached to a bench model of human anterior nares and nasal passages, and pressure measured (P). Respiratory airflows generated by a subject breathing were applied to rear of model and airflow ( V-dot ) measured via pneumotachograph. Airflow amplitude (Δ V-dot ) was plotted against pressure amplitude (ΔP). Hypopnoea detection (<50% Δ V-dot ) sensitivity and specificity was tested by expressing ΔP in terms of two reference breaths: reference breath 1, Δ V-dot 0.55 L s −1  = 100%; and reference breath 2, Δ V-dot 0.45 L s −1  = 100%. ΔP/Δ V-dot relationships were linear for Δ V-dot  ≤ 0.55 L s −1 ; ΔP = 0.37ΔV + 0.16 (nasal pressure cannula), ΔP = 2.7ΔV + 0.12 (Provent ® + proprietary nasal pressure cannula); both R 2  > 0.65, p < 0.0001; p < 0.0001 for between slope difference). For nasal pressure cannula, specificity of hypopnoea detection differed between reference breaths one and two (80.2% and 40.0%, respectively), and Provent ® + proprietary nasal pressure cannula (30.3% and 74.2%, respectively). Quantification of airflow obstruction in the presence of Provent ® + proprietary nasal pressure cannula is greatly influenced by the reference breath chosen to determine a reduction in nasal airflow. Reported variability in therapeutic response to nasal expiratory resistive devices may relate to differences in measurement technique specificity used to quantify the severity of sleep disordered breathing. (paper)

  3. Intraoperative and postoperative evaluation of low tidal volume combined with low-level positive end-expiratory pressure ventilation in laparoscopic surgery in elderly patients

    Directory of Open Access Journals (Sweden)

    Ye-Qiu Li

    2016-01-01

    Full Text Available Objective: To evaluate intraoperative and postoperative condition of low tidal volume combined with low-level positive end-expiratory pressure ventilation in laparoscopic surgery in elderly patients. Methods: A total of 176 cases of elderly patients (more than 60 years old receiving laparoscopic surgery in our hospital from July 2013 to July 2015 were selected as research subjects and randomly divided into observation group and control group, each group included 88 cases, control group received conventional ventilation strategy, observation group received low tidal volume combined with low-level positive end-expiratory pressure ventilation strategy, and then levels of hemodynamic indexes, respiratory mechanical indexes, serology indexes and cerebral vessel related indexes, etc of two groups were compared. Results: Intraoperative and postoperative heart rate and mean arterial pressure levels of observation group were lower than those of control group, arterial partial pressure of oxygen and oxygenation index levels were higher than those of control group and differences had statistical significance (P<0.05; intraoperative APIP and Pplat values of observation group were lower than those of control group, Cs value was higher than that of control group and differences had statistical significance (P<0.05; intraoperative and postoperative serum IL-8 and TNF-α levels of observation group were lower than those of control group, IL-10 level was higher than that of control group and differences had statistical significance (P<0.05; intraoperative and postoperative PjvO2, SjvO2 and CjvO2 levels of observation group were higher than those of control group, Da-jvO2 level was lower than that of control group and differences had statistical significance (P<0.05. Conclusions: When elderly patients receive laparoscopic surgery, the use of low tidal volume combined with low-level positive end-expiratory pressure ventilation strategy can stabilize hemodynamic

  4. The correlation between the paired inspiratory and expiratory three-dimensional quantitative CT and pulmonary function test in chronic obstructive pulmonary disease

    International Nuclear Information System (INIS)

    Sui Xi; Song Wei; Xue Huadan; Song Lan; Yang Liang; Jin Zhengyu

    2013-01-01

    Objective: To investigate the correlation between the paired inspiratory and expiratory quantitative CT and pulmonary function tests (PFTs) in patients with chronic obstructive pulmonary disease (COPD). Methods: A total of 84 patients with COPD were enrolled. For each patient, CT scan was performed in deep inspiration and expiration. Using automatic post-processing software, a three-dimension quantitative measurement was employed to assess the CT parameters of emphysema and air trapping. The correlation between CT and PFT was evaluated by the Spearman rank correlation test and multivariate linear regression analysis. Results: The percent 1 [Perc 1 , (-984.28 ± 17.93) HU] and percent 15 [Perc 15 , (-948.35 ± 22.26) HU] from the CT parameters of emphysema were positively correlated with the forced expiratory volume in 1 second predicted (FEV 1 %, 48.69 ± 23, 47), the ratio of forced expiratory volume in 1 second over forced vital capacity [FEV 1 /FVC, (45.89 ± 15.36)%, r = 0.45-0.67, P < 0.01], was negatively correlated with the ratio of residual volume to total lung capacity [RV/TLC, (61.32 ± 14.48)%]. The other CT parameters of emphysema index (EI) and the parameters of air trapping, the change in relative lung volume with attenuation values from -860 to -950 HU [RVC -860--950 , (17.66 ± 22.36)%], the expiration to inspiration ratio of mean lung density (MLD ex/in , 0.93 ± 0.06), the expiration to inspiration ratio of lung volume (LV ex/in , 0.71 ± 0.14) had negative correlations with logFEV 1 %, FEV 1 /FVC (r = -0.48--0.69, P < 0.01) and positive correlations with RV/TLC (r = 0.41-0.66, P < 0.01). The further univariate linear regressions showed that EI, Perc 1 , Pere 15 , RVC -860--950 , MLD ex/in , LV ex/in were correlated with the parameters of PFTs (R square values of the regression equation, ranged from 0.27 to 0.66, P < 0.01). After the pairwise combinations of the parameters of emphysema and air trapping, multivariate stepwise regressions showed

  5. Age Limits

    OpenAIRE

    Jan Antfolk

    2017-01-01

    Whereas women of all ages prefer slightly older sexual partners, men—regardless of their age—have a preference for women in their 20s. Earlier research has suggested that this difference between the sexes’ age preferences is resolved according to women’s preferences. This research has not, however, sufficiently considered that the age range of considered partners might change over the life span. Here we investigated the age limits (youngest and oldest) of considered and actual sex partners in...

  6. Effect of a mixture of pyridostigmine and atropine on forced expiratory volume (FEV1), and serum cholinesterase activity in normal subjects

    DEFF Research Database (Denmark)

    Feldt-Rasmussen, B F; Gefke, Kaj; Mosbech, H

    1985-01-01

    Pyridostigmine 0.143 mg kg-1 (maximum 10 mg) and atropine 0.0143 mg kg-1 (maximum 1 mg) were administered i.v. to six healthy male volunteers. Peripheral venous blood samples were drawn for measurement of serum cholinesterase activity. Maximum inhibition of the enzyme was found 5 min after...... injection with a decrease to 27 +/- 5% (mean +/- SEM) of the original activity. Forced expiratory volume in the first 1s (FEV1) was measured at fixed time intervals for 90 min. No decrease in FEV1 was observed; on the contrary, there was a small increase. We conclude that atropine effectively antagonizes...... the muscarinic side-effects of pyridostigmine on bronchial smooth muscle tone and bronchial secretions, when administered in clinical doses to normal human subjects....

  7. The effect of inspiratory and expiratory loads on abdominal muscle activity during breathing in subjects "at risk" for the development of chronic obstructive pulmonary disease and healthy.

    Science.gov (United States)

    Mesquita Montes, António; Crasto, Carlos; de Melo, Cristina Argel; Santos, Rita; Pereira, Susana; Vilas-Boas, João Paulo

    2017-06-01

    The abdominal muscle activity has been shown to be variable in subjects with chronic obstructive pulmonary disease (COPD) when respiratory demand increases and their recruitment pattern may change the mechanics, as well as the work and cost of breathing. The scientific evidence in subjects "at risk" for the development of COPD may be important to understand the natural history of this disease. This study aims to evaluate the effect of inspiratory and expiratory loads on the abdominal muscle activity during breathing in subjects "at risk" for the development of COPD and healthy. Thirty-one volunteers, divided in "At Risk" for COPD (n=17; 47.71±5.11years) and Healthy (n=14; 48.21±6.87years) groups, breathed at the same rhythm without load and with 10% of the maximal inspiratory or expiratory pressures, in standing. Surface electromyography was performed to assess the activation intensity of rectus abdominis (RA), external oblique and transversus abdominis/internal oblique (TrA/IO) muscles, during inspiration and expiration. During inspiration, in "At Risk" for COPD group, RA muscle activation was higher with loaded expiration (p=0.016); however, in Healthy group it was observed a higher activation of external oblique and TrA/IO muscles (pmuscle activation was higher with loaded inspiration (p=0.009), in Healthy group TrA/IO muscle showed a higher activation (p=0.025). Subjects "at risk" for the development of COPD seemed to have a specific recruitment of the superficial layer of ventrolateral abdominal wall for the mechanics of breathing. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. The effect of body mass and sex on the accuracy of respiratory magnetometers for measurement of end-expiratory lung volumes.

    Science.gov (United States)

    Avraam, Joanne; Bourke, Rosie; Trinder, John; Nicholas, Christian L; Brazzale, Danny; O'Donoghue, Fergal J; Rochford, Peter D; Jordan, Amy S

    2016-11-01

    Respiratory magnetometers are increasingly being used in sleep studies to measure changes in end-expiratory lung volume (EELV), including in obese obstructive sleep apnea patients. Despite this, the accuracy of magnetometers has not been confirmed in obese patients nor compared between sexes. Thus we compared spirometer-measured and magnetometer-estimated lung volume and tidal volume changes during voluntary end-expiratory lung volume changes of 1.5, 1, and 0.5 l above and 0.5 l below functional respiratory capacity in supine normal-weight [body mass index (BMI) 30 kg/m) men and women. Two different magnetometer calibration techniques proposed by Banzett et al. [Banzett RB, Mahan ST, Garner DM, Brughera A, Loring SH. J Appl Physiol (1985) 79: 2169-2176, 1995] and Sackner et al. [Sackner MA, Watson H, Belsito AS, Feinerman D, Suarez M, Gonzalez G, Bizousky F, Krieger B. J Appl Physiol (1985) 66: 410-420, 1989] were assessed. Across all groups and target volumes, magnetometers overestimated spirometer-measured EELV by ~65 ml (women for all target volumes except +0.5 l, whereas no differences between mass or sex groups were observed for the Sackner technique. The variability of breath-to-breath measures of EELV was significantly higher for obese compared with nonobese subjects and was higher for the Sackner than Banzett technique. On the other hand, for tidal volume, both calibration techniques underestimated spirometer measurements (men than in women (0.003). These results indicate that both body mass and sex affect the accuracy of respiratory magnetometers in measuring EELV and tidal volume. Copyright © 2016 the American Physiological Society.

  9. Modelling nasal high flow therapy effects on upper airway resistance and resistive work of breathing.

    Science.gov (United States)

    Adams, Cletus F; Geoghegan, Patrick H; Spence, Callum J; Jermy, Mark C

    2018-04-07

    The goal of this paper is to quantify upper airway resistance with and without nasal high flow (NHF) therapy. For adults, NHF therapy feeds 30-60 L/min of warm humidified air into the nose through short cannulas which do not seal the nostril. NHF therapy has been reported to increase airway pressure, increase tidal volume (V t ) and decrease respiratory rate (RR), but it is unclear how these findings affect the work done to overcome airway resistance to air flow during expiration. Also, there is little information on how the choice of nasal cannula size may affect work of breathing. In this paper, estimates of airway resistance without and with different NHF flow (applied via different cannula sizes) were made. The breathing efforts required to overcome airway resistance under these conditions were quantified. NHF was applied via three different cannula sizes to a 3-D printed human upper airway. Pressure drop and flow rate were measured and used to estimate inspiratory and expiratory upper airway resistances. The resistance information was used to compute the muscular work required to overcome the resistance of the upper airway to flow. NHF raises expiratory resistance relative to spontaneous breathing if the breathing pattern does not change but reduces work of breathing if peak expiratory flow falls. Of the cannula sizes used, the large cannula produced the greatest resistance and the small cannula produced the least. The work required to cause tracheal flow through the upper airway was reduced if the RR and minute volume are reduced by NHF. NHF has been observed to do so in COPD patients (Bräunlich et al., 2013). A reduction in I:E ratio due to therapy was found to reduce work of breathing if the peak inspiratory flow is less than the flow below which no inspiratory effort is required to overcome upper airway resistance. NHF raises expiratory resistance but it can reduce the work required to overcome upper airway resistance via a fall in inspiratory work of

  10. Limiting volume with modern ventilators.

    Science.gov (United States)

    Wing, Thomas J; Haan, Lutana; Ashworth, Lonny J; Anderson, Jeff

    2015-06-01

    The acute respiratory distress syndrome (ARDS) network low tidal-volume study comparing tidal volumes of 12 ml/kg versus 6 ml/kg was published in 2000. The study was stopped early as data revealed a 22% relative reduction in mortality rate when using 6 ml/kg tidal volume. The current generation of critical care ventilators allows the tidal volume to be set during volume-targeted, assist/control (volume A/C); however, some ventilators include options that may prevent the tidal volume from being controlled. The purpose of this bench study was to evaluate the delivered tidal volume, when these options are active, in a spontaneously breathing lung model using an electronic breathing simulator. Four ventilators were evaluated: CareFusion AVEA (AVEA), Dräger Evita® XL (Evita XL), Covidien Puritan Bennett® 840(TM) (PB 840), and Maquet SERVO-i (SERVO-i). Each ventilator was connected to the Hans Rudolph Electronic Breathing Simulator at an amplitude of 0 cm H2O and then 10 cm H2O. All four ventilators were set to deliver volume A/C, tidal volume 400 ml, respiratory rate 20 bpm, positive end-expiratory pressure 5 cm H2O, peak flowrate 60 L/min. The displayed tidal volume was recorded for each ventilator at the above settings with additional options OFF and then ON. The AVEA has two options in volume A/C: demand breaths and V-sync. When activated, these options allow the patient to exceed the set tidal volume. When using the Evita XL, the option AutoFlow can be turned ON or OFF, and when this option is ON, the tidal volume may vary. The PB 840 does not have any additional options that affect volume delivery, and it maintains the set tidal volume regardless of patient effort. The SERVO-i's demand valve allows additional flow if the patient's inspiratory flowrate exceeds the set flowrate, increasing the delivered tidal volume; this option can be turned OFF with the latest software upgrade. Modern ventilators have an increasing number of optional settings. These settings may

  11. Age Limits.

    Science.gov (United States)

    Antfolk, Jan

    2017-03-01

    Whereas women of all ages prefer slightly older sexual partners, men-regardless of their age-have a preference for women in their 20s. Earlier research has suggested that this difference between the sexes' age preferences is resolved according to women's preferences. This research has not, however, sufficiently considered that the age range of considered partners might change over the life span. Here we investigated the age limits (youngest and oldest) of considered and actual sex partners in a population-based sample of 2,655 adults (aged 18-50 years). Over the investigated age span, women reported a narrower age range than men and women tended to prefer slightly older men. We also show that men's age range widens as they get older: While they continue to consider sex with young women, men also consider sex with women their own age or older. Contrary to earlier suggestions, men's sexual activity thus reflects also their own age range, although their potential interest in younger women is not likely converted into sexual activity. Compared to homosexual men, bisexual and heterosexual men were more unlikely to convert young preferences into actual behavior, supporting female-choice theory.

  12. Age Limits

    Directory of Open Access Journals (Sweden)

    Jan Antfolk

    2017-01-01

    Full Text Available Whereas women of all ages prefer slightly older sexual partners, men—regardless of their age—have a preference for women in their 20s. Earlier research has suggested that this difference between the sexes’ age preferences is resolved according to women’s preferences. This research has not, however, sufficiently considered that the age range of considered partners might change over the life span. Here we investigated the age limits (youngest and oldest of considered and actual sex partners in a population-based sample of 2,655 adults (aged 18-50 years. Over the investigated age span, women reported a narrower age range than men and women tended to prefer slightly older men. We also show that men’s age range widens as they get older: While they continue to consider sex with young women, men also consider sex with women their own age or older. Contrary to earlier suggestions, men’s sexual activity thus reflects also their own age range, although their potential interest in younger women is not likely converted into sexual activity. Compared to homosexual men, bisexual and heterosexual men were more unlikely to convert young preferences into actual behavior, supporting female-choice theory.

  13. Low flow hydrology: a review

    CSIR Research Space (South Africa)

    Smakhtin, VU

    2001-01-10

    Full Text Available prolonged dry weather’. This definition does not make a clear distinction between low flows and droughts. Low flows is a seasonal phenomenon, and an integral component of a flow regime of any river. Drought, on the other hand, is a natural event...-flow generating mechanisms is rather limited. At the same time, identification of relative importance of various low-flow generation mechanisms and factors should ideally precede any low-flow analysis and also form an integral part of developing plans...

  14. Flow visualization

    CERN Document Server

    Merzkirch, Wolfgang

    1974-01-01

    Flow Visualization describes the most widely used methods for visualizing flows. Flow visualization evaluates certain properties of a flow field directly accessible to visual perception. Organized into five chapters, this book first presents the methods that create a visible flow pattern that could be investigated by visual inspection, such as simple dye and density-sensitive visualization methods. It then deals with the application of electron beams and streaming birefringence. Optical methods for compressible flows, hydraulic analogy, and high-speed photography are discussed in other cha

  15. Flow-dependent effect of formoterol dry-powder inhaled from the Aerolizer

    DEFF Research Database (Denmark)

    Nielsen, K G; Skov, M; Klug, B

    1997-01-01

    with exercise-induced asthma (EIA) took part in the main trial comparing the protective effect of 12 micrograms formoterol inhaled at 60 and 120 L.min-1. The effect from high and low inspiratory flow was judged from the protective effect against EIA 12 h after drug administration. The decrease in forced...... expiratory volume in one second (FEV1) after exercise was 34% on the placebo day, but only 15% when formoterol was inhaled at the high flow rate. This difference was statistically significant. The decrease in FEV1 was 23% after treatment with formoterol inhaled at the low flow rate...... a flow-dependent effect of formoterol dry powder inhaled from the Aerolizer, within the range of inspiratory flow rate obtainable by school-children. This questions its applicability in children with asthma....

  16. The acute effects of a single session of expiratory muscle strength training on blood pressure, heart rate, and oxygen saturation in healthy adults.

    Science.gov (United States)

    Laciuga, Helena; Davenport, Paul; Sapienza, Christine

    2012-01-01

    Expiratory muscle strength training (EMST) is a rehabilitative program that has been tested for outcomes related to respiratory muscle strength, cough, swallow, and voice function in healthy young adult, elderly individuals, and in patients with progressive neurodegenerative disease. Because EMST has been used in patient care, the associated cardiovascular responses during EMST are of importance. This study investigated the changes in systolic blood pressure (SBP), diastolic blood pressure (DBP), heart rate (HR), and oxygen saturation (SpO(2)) during one session of EMST in healthy, young adults as a preliminary study of device safety. Thirty-one participants completed a single session of 25 trials with the EMST device. Valsalva maneuvers were performed at the beginning and at the end of the EMST trials for task comparison. The SBP, DBP, HR, and SpO(2) were recorded at the baseline and after completing the following tasks: a Valsalva maneuver, 12 trials using the EMST device, 13 trials using the EMST device, and 5 min of rest following the EMST session. A mixed linear model tested for changes across the six time points. The results indicated no significant change of SBP, DBP, HR, or SpO(2) during or following the EMST trials or after performing the Valsalva maneuver. The results suggest that EMST does not elicit significant fluctuations of blood pressure, HR, and SpO(2) in healthy young adults even when considering the effects of covariates on the outcomes measures.

  17. Changes in Positive End-Expiratory Pressure Alter the Distribution of Ventilation within the Lung Immediately after Birth in Newborn Rabbits

    Science.gov (United States)

    Kitchen, Marcus J.; Siew, Melissa L.; Wallace, Megan J.; Fouras, Andreas; Lewis, Robert A.; Yagi, Naoto; Uesugi, Kentaro; te Pas, Arjan B.; Hooper, Stuart B.

    2014-01-01

    Current recommendations suggest the use of positive end-expiratory pressures (PEEP) to assist very preterm infants to develop a functional residual capacity (FRC) and establish gas exchange at birth. However, maintaining a consistent PEEP is difficult and so the lungs are exposed to changing distending pressures after birth, which can affect respiratory function. Our aim was to determine how changing PEEP levels alters the distribution of ventilation within the lung. Preterm rabbit pups (28 days gestation) were delivered and mechanically ventilated with one of three strategies, whereby PEEP was changed in sequence; 0-5-10-5-0 cmH2O, 5-10-0-5-0 cmH2O or 10-5-0-10-0 cmH2O. Phase contrast X-ray imaging was used to analyse the distribution of ventilation in the upper left (UL), upper right (UR), lower left (LL) and lower right (LR) quadrants of the lung. Initiating ventilation with 10PEEP resulted in a uniform increase in FRC throughout the lung whereas initiating ventilation with 5PEEP or 0PEEP preferentially aerated the UR than both lower quadrants (pventilation at 10PEEP, the distribution of air at end-inflation was uniform across all quadrants and remained so regardless of the PEEP level. Uniform distribution of ventilation can be achieved by initiating ventilation with a high PEEP. After the lungs have aerated, small and stepped reductions in PEEP result in more uniform changes in ventilation. PMID:24690890

  18. The effect of positive-end expiratory pressure on oxygenation during high frequency jet ventilation and conventional mechanical ventilation in the rabbit model of acute lung injury.

    Science.gov (United States)

    Bang, Jae Ouk; Ha, Seung Il; Choi, In-Cheol

    2012-10-01

    The use of positive end expiratory pressure (PEEP) in patients with acute lung injury (ALI) improves arterial oxygenation by alleviating pulmonary shunting, helping the respiratory muscles to decrease the work of breathing, decreasing the rate of infiltrated and atelectatic tissues, and increasing functional residual capacity. In a rabbit model of saline lavage-induced ALI, we examined the effects of PEEP on gas exchange, hemodynamics, and oxygenation during high frequency jet ventilation (HFJV), and then compared these parameters with those during conventional mechanical ventilation (CMV). Twelve rabbits underwent repeated saline lavage to create ALI. The animals were divided in 2 groups: 1) Group CMV (n = 6), and 2) Group HFJV (n = 6). In both groups, we applied 2 levels of PEEP (5 cmH(2)O and 10 cmH(2)O) and then measured the arterial blood gas, mixed venous blood gas, and hemodynamic parameters. With administration of PEEP of either 5 cmH(2)O or 10 cmH(2)O, the arterial oxygen content of both groups was increased, although without statistically significant differences between groups. On the contrary, the arterial carbon dioxide content was significantly decreased in the HFJV group, as compared with the CMV group, during the entire experiment. Furthermore, there was significant decreases in mean arterial pressures in both groups with a PEEP of 10 cmH(2)O. The application of PEEP in rabbits with ALI effectively improves oxygenation in either HFJV or CMV.

  19. Variable positive end-expiratory pressure can maintain oxygenation in experimental acute respiratory distress syndrome induced by oleic acid in dogs

    Directory of Open Access Journals (Sweden)

    F.C. Lanza

    2009-08-01

    Full Text Available The use of positive end-expiratory pressure (PEEP or lung recruitment maneuvers (RM to improve oxygenation in acute respiratory distress syndrome (ARDS is used but it may reduce cardiac output (CO. Intermittent PEEP may avoid these complications. Our objective was to determine if variable PEEP compared with constant PEEP is capable of maintaining arterial oxygenation and minimizing hemodynamic alterations with or without RM. Eighteen dogs with ARDS induced by oleic acid were randomized into three equal groups: group 1, low variable PEEP; group 2, high variable PEEP, and group 3, RM + high variable PEEP. All groups were submitted to constant PEEP, followed by variable PEEP (PEEP was increased from 5 to 10 cmH2O in group 1, and from 5 to 18 cmH2O in the other two groups. PaO2 was higher in group 3 (356.2 ± 65.4 mmHg than in group 1 (92.7 ± 29.7 mmHg and group 2 (228.5 ± 72.4 mmHg, P 0.05. Variable PEEP is able to maintain PaO2 when performed in combination with RM in dogs with ARDS. After RM, CO was reduced and there was no relevant difference between the variable and constant PEEP periods.

  20. Effects of respiratory rate, plateau pressure, and positive end-expiratory pressure on PaO2 oscillations after saline lavage.

    Science.gov (United States)

    Baumgardner, James E; Markstaller, Klaus; Pfeiffer, Birgit; Doebrich, Marcus; Otto, Cynthia M

    2002-12-15

    One of the proposed mechanisms of ventilator-associated lung injury is cyclic recruitment of atelectasis. Collapse of dependent lung regions with every breath should lead to large oscillations in PaO2 as shunt varies throughout the respiratory cycle. We placed a fluorescence-quenching PO2 probe in the brachiocephalic artery of six anesthetized rabbits after saline lavage. Using pressure-controlled ventilation with oxygen, ventilator settings were varied in random order over three levels of positive end-expiratory pressure (PEEP), respiratory rate (RR), and plateau pressure minus PEEP (Delta). Dependence of the amplitude of PaO2 oscillations on PEEP, RR, and Delta was modeled by multiple linear regression. Before lavage, arterial PO2 oscillations varied from 3 to 22 mm Hg. After lavage, arterial PO2 oscillations varied from 5 to 439 mm Hg. Response surfaces showed markedly nonlinear dependence of amplitude on PEEP, RR, and Delta. The large PaO2 oscillations observed provide evidence for cyclic recruitment in this model of lung injury. The important effect of RR on the magnitude of PaO2 oscillations suggests that the static behavior of atelectasis cannot be accurately extrapolated to predict dynamic behavior at realistic breathing frequencies.

  1. Income trusts and limited partnerships

    International Nuclear Information System (INIS)

    Toews, E.L.

    1999-01-01

    This author provided a conceptual overview of income trusts and limited partnerships that are designed to pass operating cash flow directly to investors without the imposition of corporate taxes, discussed the evolution of the market, the mechanism used to price income funds, past and present performance of the sector, and made some predictions concerning the sector's future performance. 13 figs

  2. Solubility limits on radionuclide dissolution

    Energy Technology Data Exchange (ETDEWEB)

    Kerrisk, J.F.

    1984-12-31

    This paper examines the effects of solubility in limiting dissolution rates of a number of important radionuclides from spent fuel and high-level waste. Two simple dissolution models were used for calculations that would be characteristics of a Yucca Mountain repository. A saturation-limited dissolution model, in which the water flowing through the repository is assumed to be saturated with each waste element, is very conservative in that it overestimates dissolution rates. A diffusion-limited dissolution model, in which element-dissolution rates are limited by diffusion of waste elements into water flowing past the waste, is more realistic, but it is subject to some uncertainty at this time. Dissolution rates of some elements (Pu, Am, Sn, Th, Zr, Sm) are always limited by solubility. Dissolution rates of other elements (Cs, Tc, Np, Sr, C, I) are never solubility limited; their release would be limited by dissolution of the bulk waste form. Still other elements (U, Cm, Ni, Ra) show solubility-limited dissolution under some conditions. 9 references, 3 tables.

  3. Simulation of gas compressible flow by free surface water flow

    International Nuclear Information System (INIS)

    Altafini, C.R.; Silva Ferreira, R.T. da

    1981-01-01

    The analogy between the water flow with a free surface and the compressible fluid flow, commonly called hydraulic analogy, is analyzed and its limitations are identified. The water table is the equipment used for this simulation, which allows the quatitative analysis of subsonic and supersonic flow with a low cost apparatus. The hydraulic analogy is applied to subsonic flow around circular cylinders and supersonic flow around cones. The results are compared with available theoretical and experimental data and a good agreement is achieved. (Author) [pt

  4. Influência da técnica de pressão expiratória positiva oscilante utilizando pressões expiratórias pré-determinadas na viscosidade e na transportabilidade do escarro em pacientes com bronquiectasia Influence that oscillating positive expiratory pressure using predetermined expiratory pressures has on the viscosity and transportability of sputum in patients with bronchiectasis

    Directory of Open Access Journals (Sweden)

    Ercy Mara Cipulo Ramos

    2009-12-01

    Full Text Available OBJETIVO: Verificar a efetividade da técnica de pressão expiratória positiva oscilante (PEPO utilizando pressões expiratórias pré-determinadas sobre a viscosidade e a transportabilidade do escarro em pacientes com bronquiectasia. MÉTODOS: Foram incluídos no estudo 15 pacientes estáveis com bronquiectasia (7 homens; média de idade = 53 ± 16 anos, submetidos a duas intervenções PEPO consecutivas, com 24 h de intervalo entre si, utilizando pressões expiratórias de 15 cmH2O (P15 e 25 cmH2O (P25. O protocolo consistiu de tosse voluntária; nova expectoração voluntária após 20 min, denominado tempo zero (T0; repouso de 10 min; e utilização da técnica em duas séries de 10 min (S1 e S2 de PEPO em P15 e P25, com intervalo de 10 min entre si. A viscosidade e transportabilidade do escarro foram avaliadas pela viscosimetria, velocidade relativa de transporte no palato de rã, deslocamento em máquina simuladora de tosse e ângulo de adesão. As amostras de escarro foram coletadas em T0, após S1 e após S2. Testes estatísticos específicos foram aplicados de acordo com a distribuição dos dados. RESULTADOS: Houve diminuição significante da viscosidade do escarro após S1 em P15 e após S2 em P25. Não houve diferenças significantes entre todas as amostras para a transportabilidade. CONCLUSÕES: Houve diminuição da viscosidade do escarro quando a PEPO foi realizada em P15 e P25, o que sugere que não seja necessário gerar alta pressão expiratória para obter o resultado desejado.OBJECTIVE: To determine the effectiveness of oscillating positive expiratory pressure (OPEP using predetermined expiratory pressures on the viscosity and transportability of sputum in patients with bronchiectasis. METHODS: The study involved 15 stable patients with bronchiectasis (7 males; mean age = 53 ± 16 years, submitted to two consecutive OPEP interventions, with a 24-h interval between the two, using positive expiratory pressures set at 15 cmH2O

  5. The Neopuff's PEEP valve is flow sensitive.

    LENUS (Irish Health Repository)

    Hawkes, Colin Patrick

    2012-01-31

    AIM: The current recommendation in setting up the Neopuff is to use a gas flow of 5-15 L\\/min. We investigated if the sensitivity of the positive end expiratory pressure (PEEP) valve varies at different flow rates within this range. METHODS: Five Neopuffs were set up to provide a PEEP of 5 cm H(2) O. The number of clockwise revolutions to complete occlusion of the PEEP valve and the mean and range of pressures at each quarter clockwise revolution were recorded at gas flow rates between 5 and 15 L\\/min. Results: At 5, 10 and 15 L\\/min, 0.5, 1.7 and 3.4 full clockwise rotations were required to completely occlude the PEEP valve, and pressures rose from 5 to 11.4, 18.4 and 21.5 cm H(2) O, respectively. At a flow rate of 5 L\\/min, half a rotation of the PEEP dial resulted in a rise in PEEP from 5 to 11.4cm H(2) O. At 10 L\\/min, half a rotation resulted in a rise from 5 to 7.7cm H(2) O, and at 15 L\\/min PEEP rose from 5 to 6.8cm H(2) O. CONCLUSION: Users of the Neopuff should be aware that the PEEP valve is more sensitive at lower flow rates and that half a rotation of the dial at 5 L\\/min gas flow can more than double the PEEP.

  6. The use of high-flow nasal oxygen in COPD patients

    Directory of Open Access Journals (Sweden)

    Silva Santos P

    2016-09-01

    Full Text Available Pedro Silva Santos,1 Antonio M Esquinas21Pulmonology Unit, Centro Hospitalar e Universitário de Coimbra – Hospitais da Universidade de Coimbra, Coimbra, Portugal; 2Internsive Care Unit, Hospital Morales Meseguer, Múrcia, SpainHigh-flow nasal cannula (HFNC oxygen therapy is an innovative and useful mode for the treatment of patients with respiratory failure.1–3 It delivers heated and humidified air providing higher and more expected gas flow rates and fraction inspired oxygen (FiO2 than traditional oxygen therapy.2     We read the article by Bräunlich et al1 carefully and congratulate the authors on their study about the use of nasal high-flow therapy in COPD patients. There are, however, some limitations to the study that need to be considered.    First, this study has a small number of patients, particularly in groups A and B, which in our opinion will affect the comparison of data with the group C that contains a greater variety of patients with more severe outcomes, including forced expiratory volume in 1 second and forced vital capacity. Second, as a study on mean airway pressure, it would be interesting to evaluate partial pressure of CO2 with higher flows.    Third, one of the aims of this study was to characterize changes in hypercapnia, so it is not correct to include nonhypercapnic patients. Fourth, it would be interesting to know the FiO2 that was given and whether the patients had domiciliary oxygen or noninvasive ventilation, as most of them are hypercapnic patients. Finally, regarding comfort and dyspnea scale, HFNC showed better results, which may increase its use when intolerant to noninvasive ventilation.    In short, HFNC is an interesting mode for the future treatment of COPD patients with respiratory failure, which may lead to larger and randomized trials to confirm this indication.View original paper by Bräunlich et al.

  7. Limits of mass-transfer in parallel plate dialyzers

    NARCIS (Netherlands)

    Kolev, S.D.; Kolev, Spas D.; van der Linden, W.E.

    1992-01-01

    The absolute limits of mass transfer across the membrane in a parallel-plate dialyser set by the flow pattern in both channels were determined on the basis of a mathematical model assuming axially dispersed plug flow. The lower limit corresponds to the case of mass transfer under laminar flow

  8. Perspectives on the relevance of the circadian time structure to workplace threshold limit values and employee biological monitoring.

    Science.gov (United States)

    Smolensky, Michael H; Reinberg, Alain E; Sackett-Lundeen, Linda

    2017-01-01

    The circadian time structure (CTS) and its disruption by rotating and nightshift schedules relative to work performance, accident risk, and health/wellbeing have long been areas of occupational medicine research. Yet, there has been little exploration of the relevance of the CTS to setting short-term, time-weighted, and ceiling threshold limit values (TLVs); conducting employee biological monitoring (BM); and establishing normative reference biological exposure indices (BEIs). Numerous publications during the past six decades document the CTS substantially affects the disposition - absorption, distribution, metabolism, and elimination - and effects of medications. Additionally, laboratory animal and human studies verify the tolerance to chemical, biological (contagious), and physical agents can differ extensively according to the circadian time of exposure. Because of slow and usually incomplete CTS adjustment by rotating and permanent nightshift workers, occupational chemical and other contaminant encounters occur during a different circadian stage than for dayshift workers. Thus, the intended protection of some TLVs when working the nightshift compared to dayshift might be insufficient, especially in high-risk settings. The CTS is germane to employee BM in that large-amplitude predictable-in-time 24h variation can occur in the concentration of urine, blood, and saliva of monitored chemical contaminants and their metabolites plus biomarkers indicative of adverse xenobiotic exposure. The concept of biological time-qualified (for rhythms) reference values, currently of interest to clinical laboratory pathology practice, is seemingly applicable to industrial medicine as circadian time and workshift-specific BEIs to improve surveillance of night workers, in particular. Furthermore, BM as serial assessments performed frequently both during and off work, exemplified by employee self-measurement of lung function using a small portable peak expiratory flow meter, can

  9. Experimental blunt chest trauma--cardiorespiratory effects of different mechanical ventilation strategies with high positive end-expiratory pressure: a randomized controlled study.

    Science.gov (United States)

    Schreiter, Dierk; Carvalho, Nadja C; Katscher, Sebastian; Mende, Ludger; Reske, Alexander P; Spieth, Peter M; Carvalho, Alysson R; Beda, Alessandro; Lachmann, Burkhard; Amato, Marcelo B P; Wrigge, Hermann; Reske, Andreas W

    2016-01-12

    Uncertainty persists regarding the optimal ventilatory strategy in trauma patients developing acute respiratory distress syndrome (ARDS). This work aims to assess the effects of two mechanical ventilation strategies with high positive end-expiratory pressure (PEEP) in experimental ARDS following blunt chest trauma. Twenty-six juvenile pigs were anesthetized, tracheotomized and mechanically ventilated. A contusion was applied to the right chest using a bolt-shot device. Ninety minutes after contusion, animals were randomized to two different ventilation modes, applied for 24 h: Twelve pigs received conventional pressure-controlled ventilation with moderately low tidal volumes (VT, 8 ml/kg) and empirically chosen high external PEEP (16 cmH2O) and are referred to as the HP-CMV-group. The other group (n = 14) underwent high-frequency inverse-ratio pressure-controlled ventilation (HFPPV) involving respiratory rate of 65 breaths · min(-1), inspiratory-to-expiratory-ratio 2:1, development of intrinsic PEEP and recruitment maneuvers, compatible with the rationale of the Open Lung Concept. Hemodynamics, gas exchange and respiratory mechanics were monitored during 24 h. Computed tomography and histology were analyzed in subgroups. Comparing changes which occurred from randomization (90 min after chest trauma) over the 24-h treatment period, groups differed statistically significantly (all P values for group effect <0.001, General Linear Model analysis) for the following parameters (values are mean ± SD for randomization vs. 24-h): PaO2 (100% O2) (HFPPV 186 ± 82 vs. 450 ± 59 mmHg; HP-CMV 249 ± 73 vs. 243 ± 81 mmHg), venous admixture (HFPPV 34 ± 9.8 vs. 11.2 ± 3.7%; HP-CMV 33.9 ± 10.5 vs. 21.8 ± 7.2%), PaCO2 (HFPPV 46.9 ± 6.8 vs. 33.1 ± 2.4 mmHg; HP-CMV 46.3 ± 11.9 vs. 59.7 ± 18.3 mmHg) and normally aerated lung mass (HFPPV 42.8 ± 11.8 vs. 74.6 ± 10.0 %; HP-CMV 40.7 ± 8.6 vs. 53.4 ± 11.6%). Improvements occurring after recruitment in the HFPPV-group persisted

  10. Limit, breakthrough and prosperity

    International Nuclear Information System (INIS)

    Takahashi, Minoru

    1973-01-01

    It is pointed out that the flow toward serious crises is in progress with regard to energy and industrial problems. Technical and industrial preparation and countermeasure to the flow are proposed, and the existence of a certain new world attainable on the assumption that the countermeasure is successful is described. The relation between oil output and the increasing demand for energy is pointed out as a subject matter of the crisis. The contribution of oil energy to total energy, after the output turns to decreasing process, decreases by 177.87x10 6 tons (converted to coal at the rate 6848 kcal/kg) per year at maximum. Converted to the GNP of the world, this becomes (425 dollar/ton x 177.87 x 10 6 ton=75.6 x 10 9 dollar). This fluctuation width in a year must be compensated by the change of industrial structure and energy supplying means. The countermeasure and preparation are proposed from the viewpoints of the energy and the industrial structure in which nuclear power generation plays important role. The largest production on the earth limited by energy consumption and the temperature balance on the earth is investigated, and the perspective in the future is given. (Yamamoto, Y.)

  11. Flow regimes

    International Nuclear Information System (INIS)

    Liles, D.R.

    1982-01-01

    Internal boundaries in multiphase flow greatly complicate fluid-dynamic and heat-transfer descriptions. Different flow regimes or topological configurations can have radically dissimilar interfacial and wall mass, momentum, and energy exchanges. To model the flow dynamics properly requires estimates of these rates. In this paper the common flow regimes for gas-liquid systems are defined and the techniques used to estimate the extent of a particular regime are described. Also, the current computer-code procedures are delineated and introduce a potentially better method is introduced

  12. Positive end expiratory pressure during one-lung ventilation: Selecting ideal patients and ventilator settings with the aim of improving arterial oxygenation

    Directory of Open Access Journals (Sweden)

    Hoftman Nir

    2011-01-01

    Full Text Available The efficacy of positive end-expiratory pressure (PEEP in treating intraoperative hypoxemia during one-lung ventilation (OLV remains in question given conflicting results of prior studies. This study aims to (1 evaluate the efficacy of PEEP during OLV, (2 assess the utility of preoperative predictors of response to PEEP, and (3 explore optimal intraoperative settings that would maximize the effects of PEEP on oxygenation. Forty-one thoracic surgery patients from a single tertiary care university center were prospectively enrolled in this observational study. After induction of general anesthesia, a double-lumen endotracheal tube was fiberoptically positioned and OLV initiated. Intraoperatively, PEEP = 5 and 10 cmH 2 O were sequentially applied to the ventilated lung during OLV. Arterial oxygenation, cardiovascular performance parameters, and proposed perioperative variables that could predict or enhance response to PEEP were analysed. T-test and c2 tests were utilized for continuous and categorical variables, respectively. Multivariate analyses were carried out using a classification tree model of binary recursive partitioning. PEEP improved arterial oxygenation by ≥20% in 29% of patients (n = 12 and failed to do so in 71% (n = 29; however, no cardiovascular impact was noted. Among the proposed clinical predictors, only intraoperative tidal volume per kilogram differed significantly between responders to PEEP and non-responders (mean 6.6 vs. 5.7 ml/kg, P = 0.013; no preoperative variable predicted response to PEEP. A multivariate analysis did not yield a clinically significant model for predicting PEEP responsiveness. PEEP improved oxygenation in a subset of patients; larger, although still protective tidal volumes favored a positive response to PEEP. No preoperative variables, however, could be identified as reliable predictors for PEEP responders.

  13. Predictors of response to a nasal expiratory resistor device and its potential mechanisms of action for treatment of obstructive sleep apnea.

    Science.gov (United States)

    Patel, Amit V; Hwang, Dennis; Masdeu, Maria J; Chen, Guo-Ming; Rapoport, David M; Ayappa, Indu

    2011-02-15

    A one-way nasal resistor has recently been shown to reduce sleep disordered breathing (SDB) in a subset of patients with Obstructive Sleep Apnea Hypopnea Syndrome (OSAHS). The purpose of this study was to examine characteristics predictive of therapeutic response to the device and provide pilot data as to its potential mechanisms of action. PATIENTS, INTERVENTIONS, AND MEASUREMENTS: 20 subjects (15M/5F, age 54 ± 12 years, BMI 33.5 ± 5.6 kg/m²) with OSAHS underwent 3 nocturnal polysomnograms (NPSG) including diagnostic, therapeutic (with a Provent® nasal valve device), and CPAP. Additional measurements included intranasal pressures and PCO₂, closing pressures (Pcrit), and awake lung volumes in different body positions. In 19/20 patients who slept with the device, RDI was significantly reduced with the nasal valve device compared to the diagnostic NPSG (27 ± 29/h vs 49 ± 28/h), with 50% of patients having an acceptable therapeutic response. Among demographic, lung volume, or diagnostic NPSG measures or markers of collapsibility, no significant predictors of therapeutic response were found. There was a suggestion that patients with position-dependent SDB (supine RDI > lateral RDI) were more likely to have an acceptable therapeutic response to the device. Successful elimination of SDB was associated with generation and maintenance of an elevated end expiratory pressure. No single definitive mechanism of action was elucidated. The present study shows that the nasal valve device can alter SDB across the full spectrum of SDB severity. There was a suggestion that subjects with positional or milder SDB in the lateral position were those most likely to respond.

  14. Changes in positive end-expiratory pressure alter the distribution of ventilation within the lung immediately after birth in newborn rabbits.

    Directory of Open Access Journals (Sweden)

    Marcus J Kitchen

    Full Text Available Current recommendations suggest the use of positive end-expiratory pressures (PEEP to assist very preterm infants to develop a functional residual capacity (FRC and establish gas exchange at birth. However, maintaining a consistent PEEP is difficult and so the lungs are exposed to changing distending pressures after birth, which can affect respiratory function. Our aim was to determine how changing PEEP levels alters the distribution of ventilation within the lung. Preterm rabbit pups (28 days gestation were delivered and mechanically ventilated with one of three strategies, whereby PEEP was changed in sequence; 0-5-10-5-0 cmH2O, 5-10-0-5-0 cmH2O or 10-5-0-10-0 cmH2O. Phase contrast X-ray imaging was used to analyse the distribution of ventilation in the upper left (UL, upper right (UR, lower left (LL and lower right (LR quadrants of the lung. Initiating ventilation with 10PEEP resulted in a uniform increase in FRC throughout the lung whereas initiating ventilation with 5PEEP or 0PEEP preferentially aerated the UR than both lower quadrants (p<0.05. Consequently, the relative distribution of incoming VT was preferentially directed into the lower lobes at low PEEP, primarily due to the loss of FRC in those lobes. Following ventilation at 10PEEP, the distribution of air at end-inflation was uniform across all quadrants and remained so regardless of the PEEP level. Uniform distribution of ventilation can be achieved by initiating ventilation with a high PEEP. After the lungs have aerated, small and stepped reductions in PEEP result in more uniform changes in ventilation.

  15. Effects of positive expiratory pressure on pulmonary clearance of aerosolized technetium-{sup 99m}-labeled diethylenetriaminepentaacetic acid in healthy individuals

    Energy Technology Data Exchange (ETDEWEB)

    Albuquerque, Isabella Martins de, E-mail: albuisa@gmail.com [Universidade Federal de Santa Maria (UFSM), Santa Maria, RS (Brazil). Departamento de Fisioterapia e Reabilitacao; Cardoso, Dannuey Machado; Paiva, Dulciane Nunes [Universidade de Santa Cruz do Sul, RS (Brazil); Masiero, Paulo Ricardo; Menna-Barreto, Sergio Saldanha [Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre (Brazil); Resqueti, Vanessa Regiane; Fregonezi, Guilherme Augusto de Freitas [Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil)

    2016-11-15

    Objective: To evaluate the effects of positive expiratory pressure (PEP) on pulmonary epithelial membrane permeability in healthy subjects. Methods: We evaluated a cohort of 30 healthy subjects (15 males and 15 females) with a mean age of 28.3 ± 5.4 years, a mean FEV{sub 1}/FVC ratio of 0.89 ± 0.14, and a mean FEV{sub 1} of 98.5 ± 13.1% of predicted. Subjects underwent technetium-99m labeled diethylenetriaminepentaacetic acid ({sup 99m}TcDTPA) radio aerosol inhalation lung scintigraphy in two stages: during spontaneous breathing; and while breathing through a PEP mask at one of three PEP levels—10 cmH{sub 2}O (n = 10), 15 cmH{sub 2}O (n = 10), and 20 cmH{sub 2}O (n = 10). The {sup 99m}Tc-DTPA was nebulized for 3 min, and its clearance was recorded by scintigraphy over a 30-min period during spontaneous breathing and over a 30-min period during breathing through a PEP mask. Results: The pulmonary clearance of {sup 99m}Tc-DTPA was significantly shorter when PEP was applied—at 10 cmH{sub 2}O (p = 0.044), 15 cmH{sub 2}O (p = 0.044), and 20 cmH{sub 2}O (p = 0.004) - in comparison with that observed during spontaneous breathing. Conclusions: Our findings indicate that PEP, at the levels tested, is able to induce an increase in pulmonary epithelial membrane permeability and lung volume in healthy subjects. (author)

  16. Effects of positive end-expiratory pressure and 30% inspired oxygen on pulmonary mechanics and atelectasis in cats undergoing non-bronchoscopic bronchoalveolar lavage.

    Science.gov (United States)

    Bernhard, Christa; Masseau, Isabelle; Dodam, John; Outi, Hilton; Krumme, Stacy; Bishop, Kaitlin; Graham, Amber; Reinero, Carol

    2017-06-01

    Objectives The objective of this study was to determine if modification of inspired oxygen concentration or positive end-expiratory pressure (PEEP) would alter bronchoalveolar lavage (BAL)-induced changes in pulmonary mechanics or atelectasis, as measured using ventilator-acquired pulmonary mechanics and thoracic CT. Methods Six experimentally asthmatic cats underwent anesthesia and non-bronchoscopic BAL, each under four randomized treatment conditions: 100% oxygen, zero PEEP; 30% oxygen, zero PEEP; 100% oxygen, PEEP 2 cmH 2 O; and 30% oxygen, PEEP 2 cmH 2 O. Pulse oximetry was used to estimate oxygen saturation (SpO 2 ). Ventilator-acquired pulmonary mechanics and thoracic CT scans were collected prior to BAL and at 1, 5 and 15 mins post-BAL. Results While receiving 100% oxygen, no cat had SpO 2 90% by 1 min later. There was a significant increase in airway resistance and a decrease in lung compliance following BAL, but there was no significant difference between treatment groups. Cats receiving no PEEP and 30% oxygen conserved better aeration of the lung parenchyma in BAL-sampled areas than those receiving no PEEP and 100% oxygen. Conclusions and relevance Alterations in pulmonary mechanics or atelectasis may not be reflected by SpO 2 following BAL. The use of 30% inspired oxygen concentration failed to show any significant improvement in pulmonary mechanics but did diminish atelectasis. In some cats, it was also associated with desaturation of hemoglobin. The use of PEEP in this study did not show any effect on our outcome parameters. Further studies using higher PEEP (5-10 cmH 2 O) and intermediate inspired oxygen concentration (40-60%) are warranted to determine if they would confer clinical benefit in cats undergoing diagnostic BAL.

  17. Forced Expiratory Volume in 1 Second Variability Helps Identify Patients with Cystic Fibrosis at Risk of Greater Loss of Lung Function.

    Science.gov (United States)

    Morgan, Wayne J; VanDevanter, Donald R; Pasta, David J; Foreman, Aimee J; Wagener, Jeffrey S; Konstan, Michael W

    2016-02-01

    To evaluate several alternative measures of forced expiratory volume in 1 second percent predicted (FEV1 %pred) variability as potential predictors of future FEV1 %pred decline in patients with cystic fibrosis. We included 13,827 patients age ≥6 years from the Epidemiologic Study of Cystic Fibrosis 1994-2002 with ≥4 FEV1 %pred measurements spanning ≥366 days in both a 2-year baseline period and a 2-year follow-up period. We predicted change from best baseline FEV1 %pred to best follow-up FEV1 %pred and change from baseline to best in the second follow-up year by using multivariable regression stratified by 4 lung-disease stages. We assessed 5 measures of variability (some as deviations from the best and some as deviations from the trend line) both alone and after controlling for demographic and clinical factors and for the slope and level of FEV1 %pred. All 5 measures of FEV1 %pred variability were predictive, but the strongest predictor was median deviation from the best FEV1 %pred in the baseline period. The contribution to explanatory power (R(2)) was substantial and exceeded the total contribution of all other factors excluding the FEV1 %pred rate of decline. Adding the other variability measures provided minimal additional value. Median deviation from the best FEV1 %pred is a simple metric that markedly improves prediction of FEV1 %pred decline even after the inclusion of demographic and clinical characteristics and the FEV1 %pred rate of decline. The routine calculation of this variability measure could allow clinicians to better identify patients at risk and therefore in need of increased intervention. Copyright © 2016 Elsevier Inc. All rights reserved.

  18. Impact of changes of positive end-expiratory pressure on functional residual capacity at low tidal volume ventilation during general anesthesia.

    Science.gov (United States)

    Satoh, Daizoh; Kurosawa, Shin; Kirino, Wakaba; Wagatsuma, Toshihiro; Ejima, Yutaka; Yoshida, Akiko; Toyama, Hiroaki; Nagaya, Kei

    2012-10-01

    Several reports in the literature have described the effects of positive end-expiratory pressure (PEEP) level upon functional residual capacity (FRC) in ventilated patients during general anesthesia. This study compares FRC in mechanically low tidal volume ventilation with different PEEP levels during upper abdominal surgery. Before induction of anesthesia (awake) for nine patients with upper abdominal surgery, a tight-seal facemask was applied with 2 cmH(2)O pressure support ventilation and 100 % O(2) during FRC measurements conducted on patients in a supine position. After tracheal intubation, lungs were ventilated with bilevel airway pressure with a volume guarantee (7 ml/kg predicted body weight) and with an inspired oxygen fraction (FIO(2)) of 0.4. PEEP levels of 0, 5, and 10 cmH(2)O were used. Each level of 5 and 10 cmH(2)O PEEP was maintained for 2 h. FRC was measured at each PEEP level. FRC awake was significantly higher than that at PEEP 0 cmH(2)O (P cmH(2)O was significantly lower than that at 10 cmH(2)O (P cmH(2)O (P cmH(2)O was significantly lower than that for PEEP 5 cmH(2)O or PEEP 10 cmH(2)O (P cmH(2)O, PEEP 5 cmH(2)O after 2 h, and PEEP 10 cmH(2)O after 2 h were correlated with FRC (R = 0.671, P cmH(2)O is necessary to maintain lung function if low tidal volume ventilation is used during upper abdominal surgery.

  19. Low pulmonary artery flush perfusion pressure combined with high positive end-expiratory pressure reduces oedema formation in isolated porcine lungs

    International Nuclear Information System (INIS)

    Schumann, Stefan; Schließmann, Stephan J; Wagner, Giskard; Goebel, Ulrich; Priebe, Hans-Joachim; Guttmann, Josef; Kirschbaum, Andreas

    2010-01-01

    Flush perfusion of the pulmonary artery with organ protection solution is a standard procedure before lung explantation. However, rapid flush perfusion may cause pulmonary oedema which is deleterious in the lung transplantation setting. In this study we tested the hypotheses that high pulmonary perfusion pressure contributes to the development of pulmonary oedema and positive end-expiratory pressure (PEEP) counteracts oedema formation. We expected oedema formation to increase weight and decrease compliance of the lungs on the basis of a decrease in alveolar volume as fluid replaces alveolar air spaces. The pulmonary artery of 28 isolated porcine lungs was perfused with a low-potassium dextrane solution at low (mean 27 mmHg) or high (mean 40 mmHg) pulmonary artery pressure (PAP) during mechanical ventilation at low (4 cmH 2 O) or high (8 cmH 2 O) PEEP, respectively. Following perfusion and storage, relative increases in lung weight were smaller (p < 0.05) during perfusion at low PAP (62 ± 32% and 42 ± 26%, respectively) compared to perfusion at high PAP (133 ± 54% and 87 ± 30%, respectively). Compared to all other PAP–PEEP combinations, increases in lung weight were smallest (44 ± 9% and 27 ± 12%, respectively), nonlinear intratidal lung compliance was largest (46% and 17% respectively, both p < 0.05) and lung histology showed least infiltration of mononuclear cells in the alveolar septa, and least alveolar destruction during the combination of low perfusion pressure and high PEEP. The findings suggest that oedema formation during pulmonary artery flush perfusion in isolated and ventilated lungs can be reduced by choosing low perfusion pressure and high PEEP. PAP–PEEP titration to minimize pulmonary oedema should be based on lung mechanics and PAP monitoring

  20. Effects of positive end-expiratory pressure titration and recruitment maneuver on lung inflammation and hyperinflation in experimental acid aspiration-induced lung injury.

    Science.gov (United States)

    Ambrosio, Aline M; Luo, Rubin; Fantoni, Denise T; Gutierres, Claudia; Lu, Qin; Gu, Wen-Jie; Otsuki, Denise A; Malbouisson, Luiz M S; Auler, Jose O C; Rouby, Jean-Jacques

    2012-12-01

    In acute lung injury positive end-expiratory pressure (PEEP) and recruitment maneuver are proposed to optimize arterial oxygenation. The aim of the study was to evaluate the impact of such a strategy on lung histological inflammation and hyperinflation in pigs with acid aspiration-induced lung injury. Forty-seven pigs were randomly allocated in seven groups: (1) controls spontaneously breathing; (2) without lung injury, PEEP 5 cm H2O; (3) without lung injury, PEEP titration; (4) without lung injury, PEEP titration + recruitment maneuver; (5) with lung injury, PEEP 5 cm H2O; (6) with lung injury, PEEP titration; and (7) with lung injury, PEEP titration + recruitment maneuver. Acute lung injury was induced by intratracheal instillation of hydrochloric acid. PEEP titration was performed by incremental and decremental PEEP from 5 to 20 cm H2O for optimizing arterial oxygenation. Three recruitment maneuvers (pressure of 40 cm H2O maintained for 20 s) were applied to the assigned groups at each PEEP level. Proportion of lung inflammation, hemorrhage, edema, and alveolar wall disruption were recorded on each histological field. Mean alveolar area was measured in the aerated lung regions. Acid aspiration increased mean alveolar area and produced alveolar wall disruption, lung edema, alveolar hemorrhage, and lung inflammation. PEEP titration significantly improved arterial oxygenation but simultaneously increased lung inflammation in juxta-diaphragmatic lung regions. Recruitment maneuver during PEEP titration did not induce additional increase in lung inflammation and alveolar hyperinflation. In a porcine model of acid aspiration-induced lung injury, PEEP titration aimed at optimizing arterial oxygenation, substantially increased lung inflammation. Recruitment maneuvers further improved arterial oxygenation without additional effects on inflammation and hyperinflation.

  1. Comparação entre inspirometria de incentivo e pressão positiva expiratória na função pulmonar após cirurgia bariátrica Comparison between incentive spirometry and expiratory positive airway pressure on pulmonary function after bariatric surgery

    Directory of Open Access Journals (Sweden)

    Marcela C. Barbalho-Moulim

    2009-06-01

    Full Text Available O objetivo deste estudo foi comparar o efeito da pressão positiva expiratória (EPAP, na sigla em inglês e da inspirometria de incentivo a fluxo sobre a função pulmonar após o bypass gástrico em Y de Roux por videolaparoscopia. Participaram 28 mulheres, não-tabagistas e não-pneumopatas, com índice de massa corporal entre 35 e 50 kg/m², submetidas à cirurgia bariátrica. Todas foram avaliadas por espirometria, cirtometria toracoabdominal e quanto à mobilidade diafragmática no pré e segundo dia de pós-operatório (o tempo de internação foi de 2 dias. Foram divididas em dois grupos, GI - grupo inspirômetro (n=13 e GE, grupo EPAP (n=15. A fisioterapia foi iniciada no dia da cirurgia, cada técnica, inspirometria ou EPAP, com duração de 15 minutos; a fisioterapia motora foi padronizada para ambos os grupos. No pós-operatório, houve redução similar nos dois grupos das variáveis: capacidade vital, volume de reserva inspiratório, capacidade vital forçada e ventilação voluntária máxima. Não houve alteração nos valores do volume corrente no GI e volume de reserva expiratório no GE. A mobilidade diafragmática e a mobilidade toracoabdominal foram menos prejudicadas no GI. No pós-operatório da cirurgia bariátrica por videolaparoscopia, a inspirometria de incentivo a fluxo exerceu melhores efeitos na manutenção do volume corente, na mobilidade diafragmática e toracoabdominal, enquanto a EPAP foi mais eficaz no restabelecimento do volume de reserva expiratório.The aim of this study was to compare the effect of expiratory positive airway pressure (EPAP and flow-oriented incentive spirometry on pulmonary function after laparoscopic Roux-en-Y gastric bypass surgery. Twenty-eight non-smoking women, with no lung disease and body mass index of 35 to 50 kg/m², undergoing laparoscopic gastric bypass surgery (hospitalized for two days were assessed by spirometry, thoracoabdominal cirtometry and as to diaphragmatic motion

  2. Peak flow as predictor of overall mortality in asthma and chronic obstructive pulmonary disease

    DEFF Research Database (Denmark)

    Hansen, Ejvind Frausing; Vestbo, Jørgen; Phanareth, K

    2001-01-01

    Lung function is a strong predictor of overall mortality in asthma and chronic obstructive pulmonary disease (COPD). FEV1 is considered to be the "gold standard," whereas peak expiratory flow (PEF) is mostly used in absence of FEV1 measurements. We compared the predictive power of PEF and FEV1...... reflecting different components of COPD, i.e., chronic bronchitis, small airways disease, and emphysema. Furthermore, extrapulmonary components such as muscle mass and general "vigour" probably affect PEF to a greater extent than they affect FEV1....

  3. Theoretical study of inspiratory flow waveforms during mechanical ventilation on pulmonary blood flow and gas exchange.

    Science.gov (United States)

    Niranjan, S C; Bidani, A; Ghorbel, F; Zwischenberger, J B; Clark, J W

    1999-08-01

    A lumped two-compartment mathematical model of respiratory mechanics incorporating gas exchange and pulmonary circulation is utilized to analyze the effects of square, descending and ascending inspiratory flow waveforms during mechanical ventilation. The effects on alveolar volume variation, alveolar pressure, airway pressure, gas exchange rate, and expired gas species concentration are evaluated. Advantages in ventilation employing a certain inspiratory flow profile are offset by corresponding reduction in perfusion rates, leading to marginal effects on net gas exchange rates. The descending profile provides better CO2 exchange, whereas the ascending profile is more advantageous for O2 exchange. Regional disparities in airway/lung properties create maldistribution of ventilation and a concomitant inequality in regional alveolar gas composition and gas exchange rates. When minute ventilation is maintained constant, for identical time constant disparities, inequalities in compliance yield pronounced effects on net gas exchange rates at low frequencies, whereas the adverse effects of inequalities in resistance are more pronounced at higher frequencies. Reduction in expiratory air flow (via increased airway resistance) reduces the magnitude of upstroke slope of capnogram and oxigram time courses without significantly affecting end-tidal expired gas compositions, whereas alterations in mechanical factors that result in increased gas exchanges rates yield increases in CO2 and decreases in O2 end-tidal composition values. The model provides a template for assessing the dynamics of cardiopulmonary interactions during mechanical ventilation by combining concurrent descriptions of ventilation, capillary perfusion, and gas exchange. Copyright 1999 Academic Press.

  4. Respiratory effects of low versus high tidal volume with or without positive end-expiratory pressure in anesthetized dogs with healthy lungs.

    Science.gov (United States)

    De Monte, Valentina; Bufalari, Antonello; Grasso, Salvatore; Ferrulli, Fabienne; Crovace, Alberto Maria; Lacitignola, Luca; Staffieri, Francesco

    2018-05-01

    OBJECTIVE To evaluate the impact of 2 tidal volumes (T V s) with or without positive end-expiratory pressure (PEEP) on lung mechanics, aeration, and gas exchange in healthy anesthetized dogs. ANIMALS 40 mixed-breed dogs with healthy lungs. PROCEDURES Anesthetized dogs were randomly assigned to 4 groups (n = 10/group) with different ventilatory settings: T V of 8 mL/kg and PEEP of 0 cm H 2 O (low T V group), T V of 8 mL/kg and PEEP of 5 cm H 2 O (low T V plus PEEP group), T V of 15 mL/kg and PEEP of 0 cm H 2 O (high T V group), or T V of 15 mL/kg and PEEP of 5 cm H 2 O (high T V plus PEEP group). Expired CO 2 and respiratory rate were titrated on the basis of a predetermined stepwise protocol. Gas exchange, respiratory mechanics, and pulmonary aeration were evaluated by means of CT 30 minutes after starting mechanical ventilation at the assigned setting. RESULTS Partial pressures of arterial and expired CO 2 were higher in the low T V and low T V plus PEEP groups than in the high T V and high T V plus PEEP groups. Peak and plateau airway pressures were higher in the PEEP group than in the other groups. Static lung compliance was higher in the high T V plus PEEP group than in the low T V group. Relative percentages of atelectatic and poorly aerated lung were lower in the high T V plus PEEP group than in the other groups. Oxygenation was similar among groups. CONCLUSIONS AND CLINICAL RELEVANCE Differences in T V and PEEP application during mechanical ventilation may affect respiratory function in anesthetized dogs with healthy lungs. Ventilation with a T V of 15 mL/kg and PEEP of 5 cm H 2 O significantly improved lung compliance and reduced the amount of atelectatic and poorly aerated lung.

  5. Clinical evidence on high flow oxygen therapy and active humidification in adults

    Directory of Open Access Journals (Sweden)

    C. Gotera

    2013-09-01

    Full Text Available Recently there has been growing interest in an alternative to conventional oxygen therapy: the heated, humidified high flow nasal cannula oxygen therapy (HFNC. A number of physiological effects have been described with HFNC: pharyngeal dead space washout, reduction of nasopharyngeal resistance, a positive expiratory pressure effect, an alveolar recruitment, greater humidification, more comfort and better tolerance by the patient, better control of FiO2 and mucociliary clearance. There is limited experience of HFNC in adults. There are no established guidelines or decision-making pathways to guide use of the HFNC therapy for adults. In this article we review the existing evidence of HFNC oxygen therapy in adult patients, its advantages, limitations and the current literature on clinical applications. Further research is required to determine the long-term effect of this therapy and identify the adult patient population to whom it is most beneficial. Resumo: Recentemente, uma alternativa à oxigenoterapia convencional tem recebido atenção crescente: trata-se da oxigenoterapia humidificada de alto débito com cânulas nasais (HFNC. Um número de efeitos fisiológicos têm sido descritos: «lavagem» do espaço morto faríngeo, redução da resistência da nasofarige, efeito tipo «CPAP», recrutamento alveolar, maior humidificação, maior conforto e melhor tolerância do doente, melhor controle do FiO2 e do «clearance» mucociliar. A experiência com HFNC em adultos ainda é limitada e de momento não há «guidelines» para o seu uso. Neste artigo revemos a evidência existente do uso da HFNC em adultos, as suas vantagens, limitações e a literatura mais recente sobre as suas aplicações clínicas. Mais investigação será necessária para determinar os efeitos a longo prazo desta terapêutica e identificar quais as populações em que é mais benéfica. Keywords: High flow nasal cannula, Non-invasive ventilation, Gas exchange, Respiratory

  6. Limit cycles in quantum systems

    Energy Technology Data Exchange (ETDEWEB)

    Niemann, Patrick

    2015-04-27

    In this thesis we investigate Limit Cycles in Quantum Systems. Limit cycles are a renormalization group (RG) topology. When degrees of freedom are integrated out, the coupling constants flow periodically in a closed curve. The presence of limit cycles is restricted by the necessary condition of discrete scale invariance. A signature of discrete scale invariance and limit cycles is log-periodic behavior. The first part of this thesis is concerned with the study of limit cycles with the similarity renormalization group (SRG). Limit cycles are mainly investigated within conventional renormalization group frameworks, where degrees of freedom, which are larger than a given cutoff, are integrated out. In contrast, in the SRG potentials are unitarily transformed and thereby obtain a band-diagonal structure. The width of the band structure can be regarded as an effective cutoff. We investigate the appearance of limit cycles in the SRG evolution. Our aim is to extract signatures as well as the scaling factor of the limit cycle. We consider the 1/R{sup 2}-potential in a two-body system and a three-body system with large scattering lengths. Both systems display a limit cycle. Besides the frequently used kinetic energy generator we apply the exponential and the inverse generator. In the second part of this thesis, Limit Cycles at Finite Density, we examine the pole structure of the scattering amplitude for distinguishable fermions at zero temperature in the medium. Unequal masses and a filled Fermi sphere for each fermion species are considered. We focus on negative scattering lengths and the unitary limit. The properties of the three-body spectrum in the medium and implications for the phase structure of ultracold Fermi gases are discussed.

  7. Magnetic shielding of a limiter

    International Nuclear Information System (INIS)

    Brevnov, N.N.; Stepanov, S.B.; Khimchenko, L.N.; Matthews, G.F.; Goodal, D.H.J.

    1991-01-01

    Localization of plasma interaction with material surfaces in a separate chamber, from where the escape of impurities is hardly realized, i.e. application of magnetic divertors or pump limiters, is the main technique for reduction of the impurity content in a plasma. In this case, the production of a divertor configuration requires a considerable power consumption and results in a less effective utilization of the magnetic field volume. Utilization of a pump limiter, for example the ICL-type, under tokamak-reactor conditions would result in the extremely high and forbidden local heat loadings onto the limiter surface. Moreover, the magnetically-shielded pump limiter (MSL) was proposed to combine positive properties of the divertor and the pump limiter. The idea of magnetic shielding is to locate the winding with current inside the limiter head so that the field lines of the resultant magnetic field do not intercept the limiter surface. In this case the plasma flows around the limiter leading edges and penetrates into the space under the limiter. The shielding magnetic field can be directed either counter the toroidal field or counter the poloidal one of a tokamak, dependent on the concrete diagram of the device. Such a limiter has a number of advantages: -opportunity to control over the particle and impurity recycling without practical influence upon the plasma column geometry, - perturbation of a plasma column magnetic configuration from the side of such a limiter is less than that from the side of the divertor coils. The main deficiency is the necessity to locate active windings inside the discharge chamber. (author) 5 refs., 3 figs

  8. Efficiency of osmotic pipe flows

    DEFF Research Database (Denmark)

    Haaning, Louise Sejling; Jensen, Kaare Hartvig; Helix Nielsen, Claus

    2013-01-01

    on the relative magnitude of radial diffusion and advection as well as the ratio of the osmotic velocity to pumping velocity, in very good agreement with experiments and with no adjustable parameters. Our analysis provides criteria that are useful for optimizing osmotic flow processes in, e.g., water purification......We present experiments and theory for flows of sugar or salt solutions in cylindrical tubes with semipermeable walls (hollow fiber membranes) immersed in water, quantifying the strength of the osmotic driving force in relation to the dimensionless parameters that specify the system. The pumping...... efficiency of these flows is limited by the presence of “unstirred” concentration boundary layers near the tube walls, and our primary aim is to understand and quantify these layers and their effect on the flow. We measure the outlet flow rate Qout while varying the inlet flow rate Q*, concentration c...