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Sample records for measure blood oxygen

  1. Optoacoustic measurements of human placenta and umbilical blood oxygenation

    Science.gov (United States)

    Nanovskaya, T. N.; Petrov, I. Y.; Petrov, Y.; Patrikeeva, S. L.; Ahmed, M. S.; Hankins, G. D. V.; Prough, D. S.; Esenaliev, R. O.

    2016-03-01

    Adequate oxygenation is essential for normal embryogenesis and fetal growth. Perturbations in the intrauterine oxidative environment during pregnancy are associated with several pathophysiological disorders such as pregnancy loss, preeclampsia, and intrauterine growth restriction. We proposed to use optoacoustic technology for monitoring placental and fetal umbilical blood oxygenation. In this work, we studied optoacoustic monitoring of oxygenation in placenta and umbilical cord blood ex vivo using technique of placenta perfusion. We used a medical grade, nearinfrared, tunable, optoacoustic system developed and built for oxygenation monitoring in blood vessels and in tissues. First, we calibrated the system for cord blood oxygenation measurements by using a CO-Oximeter (gold standard). Then we performed validation in cord blood circulating through the catheters localized on the fetal side of an isolated placental lobule. Finally, the oxygenation measurements were performed in the perfused placental tissue. To increase or decrease blood oxygenation, we used infusion of a gas mixture of 95% O2 + 5% CO2 and 95% N2 + 5% CO2, respectively. In placental tissue, up to four cycles of changes in oxygenation were performed. The optoacoustically measured oxygenation in circulating cord blood and in placental lobule closely correlated with the actual oxygenation data measured by CO-Oximeter. We plan to further test the placental and cord blood oxygenation monitoring with optoacoustics in animal and clinical studies.

  2. Single-cell measurement of red blood cell oxygen affinity

    OpenAIRE

    Caprio, Di; Stokes, Chris; Higgins, John M.; Schonbrun, Ethan

    2015-01-01

    Oxygen is transported throughout the body by hemoglobin in red blood cells. While the oxygen affinity of blood is well understood and is routinely assessed in patients by pulse oximetry, variability at the single-cell level has not been previously measured. In contrast, single-cell measurements of red blood cell volume and hemoglobin concentration are taken millions of times per day by clinical hematology analyzers and are important factors in determining the health of the hematologic system....

  3. Single-cell measurement of red blood cell oxygen affinity.

    Science.gov (United States)

    Di Caprio, Giuseppe; Stokes, Chris; Higgins, John M; Schonbrun, Ethan

    2015-08-11

    Oxygen is transported throughout the body by hemoglobin (Hb) in red blood cells (RBCs). Although the oxygen affinity of blood is well-understood and routinely assessed in patients by pulse oximetry, variability at the single-cell level has not been previously measured. In contrast, single-cell measurements of RBC volume and Hb concentration are taken millions of times per day by clinical hematology analyzers, and they are important factors in determining the health of the hematologic system. To better understand the variability and determinants of oxygen affinity on a cellular level, we have developed a system that quantifies the oxygen saturation, cell volume, and Hb concentration for individual RBCs in high throughput. We find that the variability in single-cell saturation peaks at an oxygen partial pressure of 2.9%, which corresponds to the maximum slope of the oxygen-Hb dissociation curve. In addition, single-cell oxygen affinity is positively correlated with Hb concentration but independent of osmolarity, which suggests variation in the Hb to 2,3-diphosphoglycerate (2-3 DPG) ratio on a cellular level. By quantifying the functional behavior of a cellular population, our system adds a dimension to blood cell analysis and other measurements of single-cell variability.

  4. Cerebral blood oxygenation measurements in neonates with optoacoustic technique

    Science.gov (United States)

    Herrmann, Stephen; Petrov, Irene Y.; Petrov, Yuriy; Richardson, C. Joan; Fonseca, Rafael A.; Prough, Donald S.; Esenaliev, Rinat O.

    2017-03-01

    Cerebral hypoxia is a major contributor to neonatal/infant mortality and morbidity including severe neurological complications such as mental retardation, cerebral palsy, motor impairment, and epilepsy. Currently, no technology is capable of accurate monitoring of neonatal cerebral oxygenation. We proposed to use optoacoustics for this application by probing the superior sagittal sinus (SSS), a large central cerebral vein. We developed and built a multi-wavelength, optical parametric oscillator (OPO) and laser diode optoacoustic systems for measurement of SSS blood oxygenation in the reflection mode through open anterior or posterior fontanelles and in the transmission mode through the skull in the occipital area. In this paper we present results of initial tests of the laser diode system for neonatal cerebral oxygenation measurements. First, the system was tested in phantoms simulating neonatal SSS. Then, using the data obtained in the phantoms, we optimized the system's hardware and software and tested it in neonates admitted in the Neonatal Intensive Care Unit. The laser diode system was capable of detecting SSS signals in the reflection mode through the open anterior and posterior fontanelles as well as in the transmission mode through the skull with high signal-to-noise ratio. Using the signals measured at different wavelengths and algorithms developed for oxygenation measurements, the laser diode system provided real-time, continuous oxygenation monitoring with high precision at all these locations.

  5. Photoacoustic measurements of red blood cell oxygen saturation in blood bags in situ

    Science.gov (United States)

    Pinto, Ruben N.; Bagga, Karan; Douplik, Alexandre; Acker, Jason P.; Kolios, Michael C.

    2017-03-01

    Red blood cell (RBC) transfusion is a critical component of the health care services. RBCs are stored in blood bags in hypothermic temperatures for a maximum of 6 weeks post donation. During this in vitro storage period, RBCs have been documented to undergo changes in structure and function due to mechanical and biochemical stress. Currently, there are no assessment methods that monitor the quality of RBCs within blood bags stored for transfusion. Conventional assessment methods require the extraction of samples, consequently voiding the sterility of the blood bags and potentially rendering them unfit for transfusions. It is hypothesized that photoacoustic (PA) technology can provide a rapid and non-invasive indication of RBC quality. In this study, a novel PA setup was developed for the acquisition of oxygen saturation (SO2) of two blood bags in situ. These measurements were taken throughout the lifespan of the blood bags (42 days) and compared against the clinical gold standard method of the blood gas analyzer (BGA). SO2 values of the blood bags increased monotonically throughout the storage period. A strong correlation between PA SO2 and BGA SO2 was found, however, PA values were on average 3.5% lower. Both techniques found the bags to increase by an SO2 of approximately 20%, and measured very similar rates of SO2 change. Future work will be focused on determining the cause of discrepancy between SO2 values acquired from PA versus BGA, as well as establishing links between the measured SO2 increase and other changes in RBC in situ.

  6. Definition, significance and measurement of quantities pertaining to the oxygen carrying properties of human blood

    NARCIS (Netherlands)

    Zijlstra, WG; Maas, AHJ; Moran, RF

    1996-01-01

    A consistent set of definitions is given of the principal quantities pertaining to the oxygen transport by the blood, and of their mutual relationships, in relation to the methods used in their measurement. At the core is the correct definition of oxygen saturation, the deviation of which has

  7. Retinal hemodynamic oxygen reactivity assessed by perfusion velocity, blood oximetry and vessel diameter measurements

    DEFF Research Database (Denmark)

    Klefter, Oliver Niels; Lauritsen, Anne Øberg; Larsen, Michael

    2015-01-01

    PURPOSE: To test the oxygen reactivity of a fundus photographic method of measuring macular perfusion velocity and to integrate macular perfusion velocities with measurements of retinal vessel diameters and blood oxygen saturation. METHODS: Sixteen eyes in 16 healthy volunteers were studied at two...... is a valid method for assessing macular perfusion. Results were consistent with previous observations of hyperoxic blood flow reduction using blue field entoptic and laser Doppler velocimetry. Retinal perfusion seemed to be regulated around individual set points according to blood glucose levels. Multimodal...

  8. The Choroidal Eye Oximeter - An instrument for measuring oxygen saturation of choroidal blood in vivo

    Science.gov (United States)

    Laing, R. A.; Danisch, L. A.; Young, L. R.

    1975-01-01

    The Choroidal Eye Oximeter is an electro-optical instrument that noninvasively measures the oxygen saturation of choroidal blood in the back of the human eye by a spectrophotometric method. Since choroidal blood is characteristic of blood which is supplied to the brain, the Choroidal Eye Oximeter can be used to monitor the amount of oxygen which is supplied to the brain under varying external conditions. The instrument consists of two basic systems: the optical system and the electronic system. The optical system produces a suitable bi-chromatic beam of light, reflects this beam from the fundus of the subject's eye, and onto a low-noise photodetector. The electronic system amplifies the weak composite signal from the photodetector, computes the average oxygen saturation from the area of the fundus that was sampled, and displays the value of the computed oxygen saturation on a panel meter.

  9. Limitations of quantitative photoacoustic measurements of blood oxygenation in small vessels

    International Nuclear Information System (INIS)

    Sivaramakrishnan, Mathangi; Maslov, Konstantin; Zhang, Hao F; Stoica, George; Wang, Lihong V

    2007-01-01

    We investigate the feasibility of obtaining accurate quantitative information, such as local blood oxygenation level (sO 2 ), with a spatial resolution of about 50 μm from spectral photoacoustic (PA) measurements. The optical wavelength dependence of the peak values of the PA signals is utilized to obtain the local blood oxygenation level. In our in vitro experimental models, the PA signal amplitude is found to be linearly proportional to the blood optical absorption coefficient when using ultrasonic transducers with central frequencies high enough such that the ultrasonic wavelengths are shorter than the light penetration depth into the blood vessels. For an optical wavelength in the 578-596 nm region, with a transducer central frequency that is above 25 MHz, the sensitivity and accuracy of sO 2 inversion is shown to be better than 4%. The effect of the transducer focal position on the accuracy of quantifying blood oxygenation is found to be negligible. In vivo oxygenation measurements of rat skin microvasculature yield results consistent with those from in vitro studies, although factors specific to in vivo measurements, such as the spectral dependence of tissue optical attenuation, dramatically affect the accuracy of sO 2 quantification in vivo

  10. New principle for measuring arterial blood oxygenation, enabling motion-robust remote monitoring

    OpenAIRE

    Mark van Gastel; Sander Stuijk; Gerard de Haan

    2016-01-01

    Finger-oximeters are ubiquitously used for patient monitoring in hospitals worldwide. Recently, remote measurement of arterial blood oxygenation (SpO2) with a camera has been demonstrated. Both contact and remote measurements, however, require the subject to remain static for accurate SpO2 values. This is due to the use of the common ratio-of-ratios measurement principle that measures the relative pulsatility at different wavelengths. Since the amplitudes are small, they are easily corrupted ...

  11. Influence of partial pressure of oxygen in blood samples on measurement performance in glucose-oxidase-based systems for self-monitoring of blood glucose.

    Science.gov (United States)

    Baumstark, Annette; Schmid, Christina; Pleus, Stefan; Haug, Cornelia; Freckmann, Guido

    2013-11-01

    Partial pressure of oxygen (pO2) in blood samples can affect blood glucose (BG) measurements, particularly in systems that employ the glucose oxidase (GOx) enzyme reaction on test strips. In this study, we assessed the impact of different pO2 values on the performance of five GOx systems and one glucose dehydrogenase (GDH) system. Two of the GOx systems are labeled by the manufacturers to be sensitive to increased blood oxygen content, while the other three GOx systems are not. Aliquots of 20 venous samples were adjusted to the following pO2 values: oxygen sensitive. © 2013 Diabetes Technology Society.

  12. Dual-wavelength photothermal optical coherence tomography for blood oxygen saturation measurement

    Science.gov (United States)

    Yin, Biwei; Kuranov, Roman V.; McElroy, Austin B.; Milner, Thomas E.

    2013-03-01

    We report design and demonstration of a dual wavelength photothermal (DWP) optical coherence tomography (OCT) system for imaging of a phantom microvessel and measurement of hemoglobin oxygen saturation (SO2) level. The DWP-OCT system contains a swept-source (SS) two-beam phase-sensitive (PhS) OCT system (1060 nm) and two intensity modulated photothermal excitation lasers (770 nm and 800 nm). The PhS-OCT probe beam (1060 nm) and photothermal excitation beams are combined into one single-mode optical fiber. A galvanometer based two-dimensional achromatic scanning system is designed to provide 14 μm lateral resolution for the PhS-OCT probe beam (1060 nm) and 13 μm lateral resolution for photothermal excitation beams. DWP-OCT system's sensitivity is 102 dB, axial resolution is 13 μm in tissue and uses a real-time digital dispersion compensation algorithm. Noise floor for optical pathlength measurements is 300 pm in the signal frequency range (380-400 Hz) of photothermal modulation frequencies. Blood SO2 level is calculated from measured optical pathlength (op) signal in a 300 μm diameter microvessel phantom introduced by the two photothermal excitation beams. En-face and B-scan images of a phantom microvessel are recorded, and six blood samples' SO2 levels are measured using DWP-OCT and compared with values provided by a commercial blood oximeter. A mathematical model indicates thermal diffusion introduces a systematic artifact that over-estimates SO2 values and is consistent with measured data.

  13. New principle for measuring arterial blood oxygenation, enabling motion-robust remote monitoring.

    Science.gov (United States)

    van Gastel, Mark; Stuijk, Sander; de Haan, Gerard

    2016-12-07

    Finger-oximeters are ubiquitously used for patient monitoring in hospitals worldwide. Recently, remote measurement of arterial blood oxygenation (SpO 2 ) with a camera has been demonstrated. Both contact and remote measurements, however, require the subject to remain static for accurate SpO 2 values. This is due to the use of the common ratio-of-ratios measurement principle that measures the relative pulsatility at different wavelengths. Since the amplitudes are small, they are easily corrupted by motion-induced variations. We introduce a new principle that allows accurate remote measurements even during significant subject motion. We demonstrate the main advantage of the principle, i.e. that the optimal signature remains the same even when the SNR of the PPG signal drops significantly due to motion or limited measurement area. The evaluation uses recordings with breath-holding events, which induce hypoxemia in healthy moving subjects. The events lead to clinically relevant SpO 2 levels in the range 80-100%. The new principle is shown to greatly outperform current remote ratio-of-ratios based methods. The mean-absolute SpO 2 -error (MAE) is about 2 percentage-points during head movements, where the benchmark method shows a MAE of 24 percentage-points. Consequently, we claim ours to be the first method to reliably measure SpO 2 remotely during significant subject motion.

  14. Detection of haemoglobins with abnormal oxygen affinity by single blood gas analysis and 2,3-diphosphoglycerate measurement.

    Science.gov (United States)

    Guerrini, G; Morabito, A; Samaja, M

    2000-10-01

    The aim is to determine if a single measurement of blood 2,3-diphosphoglycerate combined with gas analysis (pH, PCO2, PO2 and saturation) can identify the cause of an altered blood-oxygen affinity: the presence of an abnormal haemoglobin or a red cell disorder. The population (n=94) was divided into healthy controls (A, n=14), carriers of red cell disorders (B, n=72) and carriers of high oxygen affinity haemoglobins (C, n=8). Those variables were measured both in samples equilibrated at selected PCO2 and PO2 and in venous blood. In the univariable approach applied to equilibrated samples, we correctly identified C subjects in 93.6% or 96.8% of the cases depending on the selected variable, the standard P50 (PO2 at which 50% of haemoglobin is oxygenated) or a composite variable calculated from the above measurements. After introducing the haemoglobin concentration as a further discriminating variable, the A and B subjects were correctly identified in 91.9% or 94.2% of the cases, respectively. These figures become 93.0% or 86.1%, and 93.7% or 94.9% of the cases when using direct readings from venous blood, thereby avoiding the blood equilibration step. This test is feasible also in blood samples stored at 4 degrees C for 48 h, or at room temperature for 8 h.

  15. Quantification of photocatalytic oxygenation of human blood.

    Science.gov (United States)

    Subrahmanyam, Aryasomayajula; Thangaraj, Paul R; Kanuru, Chandrasekhar; Jayakumar, Albert; Gopal, Jayashree

    2014-04-01

    Photocatalytic oxygenation of human blood is an emerging concept based on the principle of photocatalytic splitting of water into oxygen and hydrogen. This communication reports: (i) a design of a photocatalytic cell (PC) that separates the blood from UV (incident) radiation source, (ii) a pH, temperature and flow controlled circuit designed for quantifying the oxygenation of human blood by photocatalysis and (iii) measuring the current efficacy of ITO/TiO2 nano thin films in oxygenating human blood in a dynamic circuit in real time. The average increase in oxygen saturation was around 5% above baseline compared to control (p<0.0005). We believe this is one of the first attempts to quantify photocatalytic oxygenation of human blood under controlled conditions. Copyright © 2013 IPEM. Published by Elsevier Ltd. All rights reserved.

  16. Influence of Partial Pressure of Oxygen in Blood Samples on Measurement Performance in Glucose-Oxidase-Based Systems for Self-Monitoring of Blood Glucose

    Science.gov (United States)

    Baumstark, Annette; Schmid, Christina; Pleus, Stefan; Haug, Cornelia; Freckmann, Guido

    2013-01-01

    Background Partial pressure of oxygen (pO2) in blood samples can affect blood glucose (BG) measurements, particularly in systems that employ the glucose oxidase (GOx) enzyme reaction on test strips. In this study, we assessed the impact of different pO2 values on the performance of five GOx systems and one glucose dehydrogenase (GDH) system. Two of the GOx systems are labeled by the manufacturers to be sensitive to increased blood oxygen content, while the other three GOx systems are not. Methods Aliquots of 20 venous samples were adjusted to the following pO2 values: pO2 ~70 mmHg, which is considered to be similar to pO2 in capillary blood samples, and the mean BG result at pO2 pO2 pO2 ≥150 mmHg. For both pO2 levels, relative differences of all tested GOx systems were significant (p pO2 values pO2 variations lead to clinically relevant BG measurement deviations in GOx systems, even in GOx systems that are not labeled as being oxygen sensitive. PMID:24351177

  17. The influence of external factors on the accuracy of non-invasive measuring of oxygen in blood

    Directory of Open Access Journals (Sweden)

    Y. M. Snizhko

    2016-05-01

    Full Text Available In this paper we investigated a pulse oximetry-based method for mobile devices. This method obtains bio-signals related to blood pulsation in transparent parts of body. The most widely accepted field for use of this method is hospital care. In these cases a pulse oximeter is the best solution for the monitoring of emergency patients. A promising field for pulse oximetry is physical exercise. It only requires simple clips such as ear-clips, finger-clips, headbands etc. However this method presents some difficulties: weak signal, noise ratio, motion artefacts, low perfusion. We used a MAX30100 Oximeter and Heart Rate Sensor integrated circuit to obtain signals of blood pulse waves from red and infrared light emission diodes (LED. This device measures the oxygen saturation of a person’s blood by placing an LED and a photodetector against the thin skin of a person’s body, such as a fingertip, wrist or earlobe. The MAX30100 is a 14-pin surface mount integrated circuit that contains sensors for measuring a person’s heart rate. It can also indirectly determine the oxygen saturation of a person’s blood. The MAX30100 provides a complete pulse oximetry and heart rate measurement solution for medical monitors and wearable fitness devices. As each LED emits light into a person’s finger, the integrated photodetector measures variations in light caused by changes in blood volume. An integrated 16-bit analog to digital converter (ADC with programmable sample rate converts the photodetector output to a digital value. The MAX30100 filters out ambient light that can interfere with an accurate reading. Data are read through a serial I2C interface to computer for further processing. The LED current can be programmed from 0 to 50 mA with proper supply voltage. The LED pulse width can be programmed from 200 µs to 1.6 ms to optimize measurement accuracy and power consumption based on use cases. The SpO2 algorithm is relatively insensitive to the wavelength

  18. Measurement of local blood flow and oxygen consumption in evolving irreversible cerebral infarction: an in vivo study in man

    International Nuclear Information System (INIS)

    Baron, J.C.; Rougemont, D.; Lebrun-Grandie, P.; Bousser, M.G.; Cabanis, E.; Bories, J.; Comar, D.; Castaigne, P.

    1982-09-01

    Positron emission tomography (PET) allows in vivo measurement of local cerebral blood flow (1CBF), oxygen consumption rate (1CMRO 2 ) and glucose utilisation (1CMRG1c) in man. Although 1CMRG1c is accessible in animals, this is not the case for 1CMRO 2 , an excellent index of local functional state. PET imaging of the local interrelationship of CBF and metabolism in completed ischemic stroke has attracted considerable interest because of its potential to differentiate irreversibly damaged from viable tissue on the basis of the CBF- metabolism patterns. Several qualitative or semi-quantitative pioneering studies provided a limited insight into this question, while the single truly quantitative study was only briefly reported. We report here a detailed study of the local CBF-CMRO 2 quantitative patterns in irreversibly infarcted brain regions

  19. Measurement of Diaphragmatic Blood Flow and Oxygen Consumption in the Dog by the Kety-Schmidt Technique

    Science.gov (United States)

    Rochester, Dudley F.

    1974-01-01

    To assess energy expenditure of the diaphragm directly, a method was devised for percutaneous catheterization of the left inferior phrenic vein in dogs. Necropsy studies, including retrograde injection of india ink and measurement of radioactivity in diaphragmatic muscle strips, suggested that the territory drained by the inferior phrenic vein was uniformly perfused, and that there were no major anastomoses between this bed and adjacent ones. Diaphragmatic blood flow (˙Q di) was calculated from the integrated diaphragmatic arteriovenous difference of 85Kr by the Kety-Schmidt technique. Diaphragmatic oxygen consumption (˙Vo2 di) was determined as the product of ˙Q di and the diaphragmatic arteriovenous oxygen content difference [(A-V)O2 di]. When lightly anesthetized dogs breathed quietly, ˙Q di was 22±SD 6 ml/min/100 g, (A-V)O2 di was 6.1±SD 2.5 ml/100 ml, and ˙VO2 di averaged 1.2±SD 0.3 ml/min/100 g. This represented 1.0±SD 0.2% of total body oxygen consumption. ˙VO2 di remained relatively constant during quiet breathing, whereas ˙Q di varied directly with cardiac output and reciprocally with (A-V)O2 di. The oxygen consumption of the noncontracting diaphragm was 60±SD 20% of the level measured during quiet breathing. The energy expended by the diaphragm to support simple hyperventilation was small. A 100% increase in minute ventilation, induced by inhalation of 5% CO2 in 21% or 14% O2, increased ˙Q di 13%, (A-V)O2 di 19%, and ˙VO2 di 40%. The diaphragm consumed 0.13±SD 0.09 ml O2 for each additional liter of ventilation. In four dogs, pneumonia appeared to increase ˙VO2 both by increasing minute ventilation and by increasing the energy cost per liter of ventilation. PMID:4825221

  20. Correlation of results obtained by in-vivo optical spectroscopy with measured blood oxygen saturation using a positive linear regression fit

    Science.gov (United States)

    McCormick, Patrick W.; Lewis, Gary D.; Dujovny, Manuel; Ausman, James I.; Stewart, Mick; Widman, Ronald A.

    1992-05-01

    Near infrared light generated by specialized instrumentation was passed through artificially oxygenated human blood during simultaneous sampling by a co-oximeter. Characteristic absorption spectra were analyzed to calculate the ratio of oxygenated to reduced hemoglobin. A positive linear regression fit between diffuse transmission oximetry and measured blood oxygenation over the range 23% to 99% (r2 equals .98, p signal was observed in the patient over time. The procedure was able to be performed clinically without difficulty; rSO2 values recorded continuously demonstrate the usefulness of the technique. Using the same instrumentation, arterial input and cerebral response functions, generated by IV tracer bolus, were deconvoluted to measure mean cerebral transit time. Date collected over time provided a sensitive index of changes in cerebral blood flow as a result of therapeutic maneuvers.

  1. Effects of breathing a hyperoxic hypercapnic gas mixture on blood oxygenation and vascularity of head-and-neck tumors as measured by magnetic resonance imaging

    International Nuclear Information System (INIS)

    Rijpkema, Mark; Kaanders, Johannes H.A.M.; Joosten, Frank; Kogel, Albert J. van der; Heerschap, Arend

    2002-01-01

    Purpose: For head-and-neck tumors, breathing a hyperoxic hypercapnic gas mixture and administration of nicotinamide has been shown to result in a significantly improved tumor response to accelerated radiotherapy (ARCON, Accelerated Radiotherapy with CarbOgen and Nicotinamide). This may be caused by improved tumor oxygenation, possibly mediated by vascular effects. In this study, both blood oxygenation and vascular effects of breathing a hyperoxic hypercapnic gas mixture (98% O 2 +2% CO 2 ) were assessed by magnetic resonance imaging (MRI) in patients with head-and-neck tumors. Methods and Materials: Tumor vascularity and oxygenation were investigated by dynamic gadolinium contrast-enhanced MRI and blood oxygen level dependent (BOLD) MRI, respectively. Eleven patients with primary head-and-neck tumors were each measured twice; with and without breathing the hyperoxic hypercapnic gas mixture. Results: BOLD MR imaging revealed a significant increase of the MRI time constant of transverse magnetization decay (T 2 *) in the tumor during hypercapnic hyperoxygenation, which correlates to a decrease of the deoxyhemoglobin concentration. No changes in overall tumor vascularity were observed, as measured by the gadolinium contrast uptake rate in the tumor. Conclusion: Breathing a hyperoxic hypercapnic gas mixture improves tumor blood oxygenation in patients with head-and-neck tumors, which may contribute to the success of the ARCON therapy

  2. Skin Blood Perfusion and Oxygenation Colour Affect Perceived Human Health

    Science.gov (United States)

    Stephen, Ian D.; Coetzee, Vinet; Law Smith, Miriam; Perrett, David I.

    2009-01-01

    Skin blood perfusion and oxygenation depends upon cardiovascular, hormonal and circulatory health in humans and provides socio-sexual signals of underlying physiology, dominance and reproductive status in some primates. We allowed participants to manipulate colour calibrated facial photographs along empirically-measured oxygenated and deoxygenated blood colour axes both separately and simultaneously, to optimise healthy appearance. Participants increased skin blood colour, particularly oxygenated, above basal levels to optimise healthy appearance. We show, therefore, that skin blood perfusion and oxygenation influence perceived health in a way that may be important to mate choice. PMID:19337378

  3. MR measures of renal perfusion, oxygen bioavailability and total renal blood flow in a porcine model: noninvasive regional assessment of renal function.

    Science.gov (United States)

    Wentland, Andrew L; Artz, Nathan S; Fain, Sean B; Grist, Thomas M; Djamali, Arjang; Sadowski, Elizabeth A

    2012-01-01

    Magnetic resonance imaging (MRI) may be a useful adjunct to current methods of evaluating renal function. MRI is a noninvasive imaging modality that has the ability to evaluate the kidneys regionally, which is lacking in current clinical methods. Other investigators have evaluated renal function with MRI-based measurements, such as with techniques to measure cortical and medullary perfusion, oxygen bioavailability and total renal blood flow (TRBF). However, use of all three techniques simultaneously, and therefore the relationships between these MRI-derived functional parameters, have not been reported previously. To evaluate the ability of these MRI techniques to track changes in renal function, we scanned 11 swine during a state of hyperperfusion with acetylcholine and a saline bolus and subsequently scanned during a state of hypoperfusion with the prolonged use of isoflurane anesthesia. For each time point, measurements of perfusion, oxygen bioavailability and TRBF were acquired. Measurements of perfusion and oxygen bioavailability were compared with measurements of TRBF for all swine across all time points. Cortical perfusion, cortical oxygen bioavailability, medullary oxygen bioavailability and TRBF significantly increased with the acetylcholine challenge. Cortical perfusion, medullary perfusion, cortical oxygen bioavailability and TRBF significantly decreased during isoflurane anesthesia. Cortical perfusion (Spearman's correlation coefficient = 0.68; P renal function. Maintenance of the medullary oxygen bioavailability in low blood flow states may reflect the autoregulation particular to this region of the kidney. The ability to non-invasively measure all three parameters of kidney function in a single MRI examination and to evaluate the relationships between these functional parameters is potentially useful for evaluating the state of the human kidneys in situ in future studies.

  4. Quantitative spatially resolved measurement of tissue chromophore concentrations using photoacoustic spectroscopy: application to the measurement of blood oxygenation and haemoglobin concentration

    Science.gov (United States)

    Laufer, Jan; Delpy, Dave; Elwell, Clare; Beard, Paul

    2007-01-01

    A new approach based on pulsed photoacoustic spectroscopy for non-invasively quantifying tissue chromophore concentrations with high spatial resolution has been developed. The technique is applicable to the quantification of tissue chromophores such as oxyhaemoglobin (HbO2) and deoxyhaemoglobin (HHb) for the measurement of physiological parameters such as blood oxygen saturation (SO2) and total haemoglobin concentration. It can also be used to quantify the local accumulation of targeted contrast agents used in photoacoustic molecular imaging. The technique employs a model-based inversion scheme to recover the chromophore concentrations from photoacoustic measurements. This comprises a numerical forward model of the detected time-dependent photoacoustic signal that incorporates a multiwavelength diffusion-based finite element light propagation model to describe the light transport and a time-domain acoustic model to describe the generation, propagation and detection of the photoacoustic wave. The forward model is then inverted by iteratively fitting it to measurements of photoacoustic signals acquired at different wavelengths to recover the chromophore concentrations. To validate this approach, photoacoustic signals were generated in a tissue phantom using nanosecond laser pulses between 740 nm and 1040 nm. The tissue phantom comprised a suspension of intralipid, blood and a near-infrared dye in which three tubes were immersed. Blood at physiological haemoglobin concentrations and oxygen saturation levels ranging from 2% to 100% was circulated through the tubes. The signal amplitude from different temporal sections of the detected photoacoustic waveforms was plotted as a function of wavelength and the forward model fitted to these data to recover the concentrations of HbO2 and HHb, total haemoglobin concentration and SO2. The performance was found to compare favourably to that of a laboratory CO-oximeter with measurement resolutions of ±3.8 g l-1 (±58 µM) and ±4

  5. Quantitative spatially resolved measurement of tissue chromophore concentrations using photoacoustic spectroscopy: application to the measurement of blood oxygenation and haemoglobin concentration

    Energy Technology Data Exchange (ETDEWEB)

    Laufer, Jan; Delpy, Dave; Elwell, Clare; Beard, Paul [Department of Medical Physics and Bioengineering, University College London, Malet Place Engineering Building, London WC1E 6BT (United Kingdom)

    2007-01-07

    A new approach based on pulsed photoacoustic spectroscopy for non-invasively quantifying tissue chromophore concentrations with high spatial resolution has been developed. The technique is applicable to the quantification of tissue chromophores such as oxyhaemoglobin (HbO{sub 2}) and deoxyhaemoglobin (HHb) for the measurement of physiological parameters such as blood oxygen saturation (SO{sub 2}) and total haemoglobin concentration. It can also be used to quantify the local accumulation of targeted contrast agents used in photoacoustic molecular imaging. The technique employs a model-based inversion scheme to recover the chromophore concentrations from photoacoustic measurements. This comprises a numerical forward model of the detected time-dependent photoacoustic signal that incorporates a multiwavelength diffusion-based finite element light propagation model to describe the light transport and a time-domain acoustic model to describe the generation, propagation and detection of the photoacoustic wave. The forward model is then inverted by iteratively fitting it to measurements of photoacoustic signals acquired at different wavelengths to recover the chromophore concentrations. To validate this approach, photoacoustic signals were generated in a tissue phantom using nanosecond laser pulses between 740 nm and 1040 nm. The tissue phantom comprised a suspension of intralipid, blood and a near-infrared dye in which three tubes were immersed. Blood at physiological haemoglobin concentrations and oxygen saturation levels ranging from 2% to 100% was circulated through the tubes. The signal amplitude from different temporal sections of the detected photoacoustic waveforms was plotted as a function of wavelength and the forward model fitted to these data to recover the concentrations of HbO{sub 2} and HHb, total haemoglobin concentration and SO{sub 2}. The performance was found to compare favourably to that of a laboratory CO-oximeter with measurement resolutions of {+-}3

  6. Quantitative spatially resolved measurement of tissue chromophore concentrations using photoacoustic spectroscopy: application to the measurement of blood oxygenation and haemoglobin concentration

    International Nuclear Information System (INIS)

    Laufer, Jan; Delpy, Dave; Elwell, Clare; Beard, Paul

    2007-01-01

    A new approach based on pulsed photoacoustic spectroscopy for non-invasively quantifying tissue chromophore concentrations with high spatial resolution has been developed. The technique is applicable to the quantification of tissue chromophores such as oxyhaemoglobin (HbO 2 ) and deoxyhaemoglobin (HHb) for the measurement of physiological parameters such as blood oxygen saturation (SO 2 ) and total haemoglobin concentration. It can also be used to quantify the local accumulation of targeted contrast agents used in photoacoustic molecular imaging. The technique employs a model-based inversion scheme to recover the chromophore concentrations from photoacoustic measurements. This comprises a numerical forward model of the detected time-dependent photoacoustic signal that incorporates a multiwavelength diffusion-based finite element light propagation model to describe the light transport and a time-domain acoustic model to describe the generation, propagation and detection of the photoacoustic wave. The forward model is then inverted by iteratively fitting it to measurements of photoacoustic signals acquired at different wavelengths to recover the chromophore concentrations. To validate this approach, photoacoustic signals were generated in a tissue phantom using nanosecond laser pulses between 740 nm and 1040 nm. The tissue phantom comprised a suspension of intralipid, blood and a near-infrared dye in which three tubes were immersed. Blood at physiological haemoglobin concentrations and oxygen saturation levels ranging from 2% to 100% was circulated through the tubes. The signal amplitude from different temporal sections of the detected photoacoustic waveforms was plotted as a function of wavelength and the forward model fitted to these data to recover the concentrations of HbO 2 and HHb, total haemoglobin concentration and SO 2 . The performance was found to compare favourably to that of a laboratory CO-oximeter with measurement resolutions of ±3.8 g l -1 (±58

  7. 21 CFR 868.1200 - Indwelling blood oxygen partial pressure (PO2) analyzer.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Indwelling blood oxygen partial pressure (PO2... Indwelling blood oxygen partial pressure (PO2) analyzer. (a) Identification. An indwelling blood oxygen... electrode) and that is used to measure, in vivo, the partial pressure of oxygen in blood to aid in...

  8. A system for oxygen-15 labeled blood for medical applications

    International Nuclear Information System (INIS)

    Subramanyam, R.; Bucelewicz, W.M.; Hoop, B. Jr.; Jones, S.C.

    1977-01-01

    Oxygen-15 labeled compounds in blood have been used successfully for cerebral circulation and cerebral oxygen metabolism measurements. The present paper describes a system for the rapid sequential production of 15 O-HgB, C 15 O-Hgb and H 2 15 O in blood under sterile and pyrogen-free conditions. A tonometer has been adopted for labeling blood without hemolysis and foam production. (author)

  9. Blood conservation with membrane oxygenators and dipyridamole.

    Science.gov (United States)

    Teoh, K H; Christakis, G T; Weisel, R D; Madonik, M M; Ivanov, J; Wong, P Y; Mee, A V; Levitt, D; Benak, A; Reilly, P

    1987-07-01

    Cardiopulmonary bypass induces platelet activation and dysfunction, which result in platelet deposition and depletion. Reduced platelet numbers and abnormal platelet function may contribute to postoperative bleeding. A membrane oxygenator may preserve platelets and reduce bleeding more than a bubble oxygenator, and the antiplatelet agent dipyridamole may protect platelets intraoperatively and reduce bleeding postoperatively. A prospective randomized trial was performed in 44 patients undergoing elective coronary artery bypass grafting to assess the effects of the membrane oxygenator and dipyridamole on platelet counts, platelet activation products, and postoperative bleeding. Patients who were randomized to receive a bubble oxygenator and no dipyridamole had the lowest postoperative platelet counts, the greatest blood loss, and the most blood products transfused. Platelet counts were highest and blood loss was least in patients randomized to receive a membrane oxygenator and dipyridamole (p less than .05). A bubble oxygenator with dipyridamole and a membrane oxygenator without dipyridamole resulted in intermediate postoperative platelet counts and blood loss. Arterial thromboxane B2 and platelet factor 4 concentrations were elevated on cardiopulmonary bypass in all groups. Both the membrane oxygenator and dipyridamole were independently effective (by multivariate analysis) in preserving platelets. Optimal blood conservation was achieved with a membrane oxygenator and dipyridamole.

  10. Brain magnetic resonance imaging with contrast dependent on blood oxygenation

    International Nuclear Information System (INIS)

    Ogawa, S.; Lee, T.M.; Kay, A.R.; Tank, D.W.

    1990-01-01

    Paramagnetic deoxyhemoglobin in venous blood is a naturally occurring contrast agent for magnetic resonance imaging (MRI). By accentuating the effects of this agent through the use of gradient-echo techniques in high yields, the authors demonstrate in vivo images of brain microvasculature with image contrast reflecting the blood oxygen level. This blood oxygenation level-dependent (BOLD) contrast follows blood oxygen changes induced by anesthetics, by insulin-induced hypoglycemia, and by inhaled gas mixtures that alter metabolic demand or blood flow. The results suggest that BOLD contrast can be used to provide in vivo real-time maps of blood oxygenation in the brain under normal physiological conditions. BOLD contrast adds an additional feature to magnetic resonance imaging and complement other techniques that are attempting to provide position emission tomography-like measurements related to regional neural activity

  11. Simultaneous measurement of cerebral blood flow and oxygen extraction fraction by positron emission tomography: theoretical study and experimental evidence of cerebral blood flow measurement with the C15O2 continuous inhalation technique

    International Nuclear Information System (INIS)

    Steinling, M.

    1983-01-01

    The method of the continuous inhalation technique of oxygen-15 labelled CO 2 coupled with positron emission tomography for the measurement of cerebral blood flow (C.B.F.) is described. An indirect experimental verification that this technique allowed the measurement of C.B.F. has been carried out in baboons by showing the expected change in the measured parameter with variations in the PaCO 2 . A critical investigation of the C 15 O 2 model was performed. The amount of tracer present in the cerebral vascular pool has a negligible effect on C.B.F. value. The use of a mean brain-blood partition coefficient of water instead of that specific to gray or to white matter is commented upon, and its influence on the final C.B.F. value is studied. Lastly, the problem of the limited diffusion of water across the blood-brain-barrier is discussed. The study of the combined effects of gray-white mixing and limited wates extraction of the C.B.F. value shows that the C 15 O 2 technique tends to understimate real C.B.F., and that this error is more severe with high flows and even gray white mixing. These limitations do not depart from the possibility to estimate in the same brain locus not only C.B.F. but oxygen utilization as well by the consecutive inhalation of C 15 O 2 and 15 O 2 . The advantages of this possibility has already been shown in a number of clinical studies [fr

  12. Measuring vascular reactivity with resting-state blood oxygenation level-dependent (BOLD) signal fluctuations: A potential alternative to the breath-holding challenge?

    Science.gov (United States)

    Jahanian, Hesamoddin; Christen, Thomas; Moseley, Michael E; Pajewski, Nicholas M; Wright, Clinton B; Tamura, Manjula K; Zaharchuk, Greg

    2017-07-01

    Measurement of the ability of blood vessels to dilate and constrict, known as vascular reactivity, is often performed with breath-holding tasks that transiently raise arterial blood carbon dioxide (P a CO 2 ) levels. However, following the proper commands for a breath-holding experiment may be difficult or impossible for many patients. In this study, we evaluated two approaches for obtaining vascular reactivity information using blood oxygenation level-dependent signal fluctuations obtained from resting-state functional magnetic resonance imaging data: physiological fluctuation regression and coefficient of variation of the resting-state functional magnetic resonance imaging signal. We studied a cohort of 28 older adults (69 ± 7 years) and found that six of them (21%) could not perform the breath-holding protocol, based on an objective comparison with an idealized respiratory waveform. In the subjects that could comply, we found a strong linear correlation between data extracted from spontaneous resting-state functional magnetic resonance imaging signal fluctuations and the blood oxygenation level-dependent percentage signal change during breath-holding challenge ( R 2  = 0.57 and 0.61 for resting-state physiological fluctuation regression and resting-state coefficient of variation methods, respectively). This technique may eliminate the need for subject cooperation, thus allowing the evaluation of vascular reactivity in a wider range of clinical and research conditions in which it may otherwise be impractical.

  13. Blood oxygenation level dependent (BOLD). Renal imaging. Concepts and applications

    International Nuclear Information System (INIS)

    Nissen, Johanna C.; Haneder, Stefan; Schoenberg, Stefan O.; Michaely, Henrik J.

    2010-01-01

    Many renal diseases as well as several pharmacons cause a change in renal blood flow and/or renal oxygenation. The blood oxygenation level dependent (BOLD) imaging takes advantage of local field inhomogeneities and is based on a T2 * -weighted sequence. BOLD is a non-invasive method allowing an estimation of the renal, particularly the medullary oxygenation, and an indirect measurement of blood flow without administration of contrast agents. Thus, effects of different drugs on the kidney and various renal diseases can be controlled and observed. This work will provide an overview of the studies carried out so far and identify ways how BOLD can be used in clinical studies. (orig.)

  14. Toe blood pressure and leg muscle oxygenation with body posture.

    Science.gov (United States)

    Rosales-Velderrain, Armando; Cardno, Michael; Mateus, Jaime; Kumar, Ravindra; Schlabs, Thomas; Hargens, Alan R

    2011-05-01

    In 1980 Katkov and Chestukhin measured blood pressures and oxygenation invasively at various body tilt angles at different locations on the body, including the foot. To our knowledge, such measurements have not been performed noninvasively. Therefore, the purpose of this study was to measure toe blood pressure (TBP) and lower limb muscle oxygenation noninvasively at various body tilt angles, and to assess the use of a Finometer for noninvasive TBP measurements. Our noninvasive results are compared with those performed by Katkov and Chestukhin. We hypothesized that: 1) the Finometer provides a noninvasive measurement of TBP at different tilt angles; and 2) muscle oxygenation is highest with 0 and -6 degrees, and decreases with increased head-up tilt (HUT). There were 10 subjects who were exposed to different body tilt angles (-6, 0, 10, 30, 70, and 90 degrees). At each angle we measured TBP noninvasively with a Finometer and muscle tissue oxygenation by near infrared spectroscopy. We found a strong correlation between TBP using the Finometer and TBP predicted by adding the hydrostatic component due to body tilt to the standard arm blood pressure measurement. At 10, 30, 70, and 90 degrees both TBP and tissue oxygenation were significantly different from the 0 degree (supine) level. Oxygenation decreased and TBP increased with higher HUT angles. No differences were observed in TBP or oxygenation between -6 and 0 degree. The Finometer accurately measures TBP noninvasively with body tilt. Also, muscle oxygenation is highest at small HUT angles and decreases with increased HUT.

  15. Measurement of forearm oxygen consumption

    DEFF Research Database (Denmark)

    Astrup, A; Simonsen, L; Bülow, J

    1988-01-01

    The classical forearm technique widely used for studies of skeletal muscle metabolism requires arterial cannulation. To avoid arterial puncture it is becoming more common to arterialize blood from a contralateral hand vein by local heating. This modification and the classical method have produced...... blood flow and decreases skeletal muscle blood flow. This facilitates mixing of superficial blood with deep venous blood. Contralateral heating increased deep venous oxygen saturation and abolished the pronounced glucose-induced increase in oxygen consumption observed in the control experiments after...... contradictory results regarding the contribution of skeletal muscle to glucose-induced thermogenesis. The effect on forearm circulation and the metabolism of heating the contralateral hand was examined before and after an oral glucose load. The results suggest that contralateral heating increases subcutaneous...

  16. Measuring arterial oxygenation in a high altitude field environment: comparing portable pulse oximetry with blood gas analysis.

    Science.gov (United States)

    Ross, Elliot M; Matteucci, Michael J; Shepherd, Matthew; Barker, Matthew; Orr, Lance

    2013-06-01

    High altitude environments present unique medical treatment challenges. Medical providers often use small portable pulse oximetry devices to help guide their clinical decision making. A significant body of high altitude research is based on the use of these devices to monitor hypoxia, yet there is a paucity of evidence that these devices are accurate in these environments. We studied whether these devices perform accurately and reliably under true mountain conditions. Healthy unacclimatized active-duty military volunteers participating in mountain warfare training at 2100 m (6900 feet) above sea level were evaluated with several different pulse oximetry devices while in a cold weather, high altitude field environment and then had arterial blood gases (ABG) drawn using an i-STAT for comparison. The pulse oximeter readings were compared with the gold standard ABG readings. A total of 49 individuals completed the study. There was no statistically significant difference between any of the devices and the gold standard of ABG. The best performing device was the PalmSAT (PS) 8000SM finger probe with a mean difference of 2.17% and SD of 2.56 (95% CI, 1.42% to 2.92%). In decreasing order of performance were the PS 8000AA finger probe (mean ± SD, 2.54% ± 2.68%; 95% CI, 1.76% to 3.32%), the PS 8000Q ear probe (2.47% ± 4.36%; 95% CI, 1.21% to 3.75%), the Nonin Onyx 9500 (3.29% ± 3.12%; 95% CI, 2.39% to 4.20%), and finally the PS 8000R forehead reflectance sensor (5.15% ± 2.97%; 95% CI, 4.28% to 6.01%). Based on the results of this study, results of the newer portable pulse oximeters appear to be closely correlated to that of the ABG measurements when tested in true mountain conditions. Copyright © 2013 Wilderness Medical Society. Published by Elsevier Inc. All rights reserved.

  17. Time-dependent correlation of cerebral blood flow with oxygen metabolism in activated human visual cortex as measured by fMRI.

    Science.gov (United States)

    Lin, Ai-Ling; Fox, Peter T; Yang, Yihong; Lu, Hanzhang; Tan, Li-Hai; Gao, Jia-Hong

    2009-01-01

    The aim of this study was to investigate the relationship between relative cerebral blood flow (delta CBF) and relative cerebral metabolic rate of oxygen (delta CMRO(2)) during continuous visual stimulation (21 min at 8 Hz) with fMRI biophysical models by simultaneously measuring of BOLD, CBF and CBV fMRI signals. The delta CMRO(2) was determined by both a newly calibrated single-compartment model (SCM) and a multi-compartment model (MCM) and was in agreement between these two models (P>0.5). The duration-varying delta CBF and delta CMRO(2) showed a negative correlation with time (r=-0.97, PSCM, an incorrect and even an opposite appearance of the flow-metabolism relationship during prolonged visual stimulation (positively linear coupling) can result. The time-dependent negative correlation between flow and metabolism demonstrated in this fMRI study is consistent with a previous PET observation and further supports the view that the increase in CBF is driven by factors other than oxygen demand and the energy demands will eventually require increased aerobic metabolism as stimulation continues.

  18. Improved sample capsule for determination of oxygen in hemolyzed blood

    Science.gov (United States)

    Malik, W. M.

    1967-01-01

    Sample capsule for determination of oxygen in hemolyzed blood consists of a measured section of polytetrafluoroethylene tubing equipped at each end with a connector and a stopcock valve. This method eliminates errors from air entrainment or from the use of mercury or syringe lubricant.

  19. Database of normal human cerebral blood flow, cerebral blood volume, cerebral oxygen extraction fraction and cerebral metabolic rate of oxygen measured by positron emission tomography with {sup 15}O-labelled carbon dioxide or water, carbon monoxide and oxygen: a multicentre study in Japan

    Energy Technology Data Exchange (ETDEWEB)

    Ito, Hiroshi [Department of Radiology and Nuclear Medicine, Akita Research Institute of Brain and Blood Vessels, Akita (Japan); Department of Nuclear Medicine and Radiology, Division of Brain Sciences, Institute of Development, Aging and Cancer, Tohoku University, 4-1 Seiryo-Machi, 980-8575, Aoba-Ku, Sendai (Japan); Kanno, Iwao [Department of Radiology and Nuclear Medicine, Akita Research Institute of Brain and Blood Vessels, Akita (Japan); Kato, Chietsugu [Department of Nuclear Medicine, Hokkaido University School of Medicine, Sapporo (Japan); Sasaki, Toshiaki [Cyclotoron Research Center, Iwate Medical University, Morioka (Japan); Ishii, Kenji [Positron Medical Center, Tokyo Metropolitan Institute of Gerontology, Tokyo (Japan); Ouchi, Yasuomi [Positron Medical Center, Hamamatsu Medical Center, Hamakita (Japan); Iida, Akihiko [Nagoya City Rehabilitation Center, Nagoya (Japan); Okazawa, Hidehiko [PET Unit, Research Institute, Shiga Medical Center, Moriyama (Japan); Hayashida, Kohei [Department of Radiology, National Cardiovascular Center, Suita, Osaka (Japan); Tsuyuguchi, Naohiro [Department of Neurosurgery, Osaka City University Medical School, Osaka (Japan); Ishii, Kazunari [Division of Imaging Research, Hyogo Institute for Aging Brain and Cognitive Disorders, Himeji, Hyogo (Japan); Kuwabara, Yasuo [Department of Radiology, Faculty of Medicine, Kyushu University, Fukuoka (Japan); Senda, Michio [Department of Image-based Medicine, Institute of Biomedical Research and Innovation, Kobe (Japan)

    2004-05-01

    Measurement of cerebral blood flow (CBF), cerebral blood volume (CBV), cerebral oxygen extraction fraction (OEF) and cerebral metabolic rate of oxygen (CMRO{sub 2}) by positron emission tomography (PET) with oxygen-15 labelled carbon dioxide (C{sup 15}O{sub 2}) or {sup 15}O-labelled water (H{sub 2}{sup 15}O), {sup 15}O-labelled carbon monoxide (C{sup 15}O) and {sup 15}O-labelled oxygen ({sup 15}O{sub 2}) is useful for diagnosis and treatment planning in cases of cerebrovascular disease. The measured values theoretically depend on various factors, which may differ between PET centres. This study explored the applicability of a database of {sup 15}O-PET by examining between-centre and within-centre variation in values. Eleven PET centres participated in this multicentre study; seven used the steady-state inhalation method, one used build-up inhalation and three used bolus administration of C{sup 15}O{sub 2} (or H{sub 2}{sup 15}O) and {sup 15}O{sub 2}. All used C{sup 15}O for measurement of CBV. Subjects comprised 70 healthy volunteers (43 men and 27 women; mean age 51.8{+-}15.1 years). Overall mean{+-}SD values for cerebral cortical regions were: CBF=44.4{+-}6.5 ml 100 ml{sup -1} min{sup -1}; CBV=3.8{+-}0.7 ml 100 ml{sup -1}; OEF=0.44{+-}0.06; CMRO{sub 2}=3.3{+-}0.5 ml 100 ml{sup -1} min{sup -1}. Significant between-centre variation was observed in CBV, OEF and CMRO{sub 2} by one-way analysis of variance. However, the overall inter-individual variation in CBF, CBV, OEF and CMRO{sub 2} was acceptably small. Building a database of normal cerebral haemodynamics obtained by the{sup 15}O-PET methods may be practicable. (orig.)

  20. [Simultaneous determinations of oxygen partial pressure in the scala tympani, electrocochleography and blood pressure measurements in noise stress in guinea pigs].

    Science.gov (United States)

    Lamm, K; Lamm, C; Lamm, H; Schumann, K

    1988-09-01

    In 14 guinea pigs the pO2 in the perilymph of the scala tympani fell to 50%-80% of the original value during exposure to noise consisting of 4,000 Hz clicks with a repetition rate of 20/s, 100 dB CHL = 120 dB SPL p.e., repeated twice over a period of 24 minutes each time. For the measurements of the pO2 we used the thin 0.5 micron micro-coaxial needle electrode described by Baumgärtl and Luebbers, which was placed through the round-window membrane in the scala tympani to a depth of 600 micron. The simultaneously recorded CAP latency times were prolonged by 0.8 ms at a test loudness of 60 and 80 dB CHL. The amplitudes of the CM had declined by 60%-70% of the original values at a test loudness of 80 dB SPL p.e. The intra-arterial blood pressure in the common carotid artery of all animals remained constant. As the cortilymph spaces communicate with the perilymph of the scala tympani, our measured decline of pO2 in the perilymph could indicate a cortilymph hypoxia. During exposure to noise the oxygen-dependent Na+ and K+ pumps, which maintain the ion balance and function of the organ of Corti, can decompensate due to lack of oxygen. That would lead to a K+ contamination of the cortilymph and to an intracellular Na+ accumulation, which can cause microstructural damage (hair cell-cilia fusion, hair cell, synaptic and dendritic swelling, hair cell contraction and sustained depolarization), which would be reflected in the CMs and CAPs.

  1. Blood banking-induced alteration of red blood cell oxygen release ability.

    Science.gov (United States)

    Li, Yaojin; Xiong, Yanlian; Wang, Ruofeng; Tang, Fuzhou; Wang, Xiang

    2016-05-01

    Current blood banking procedures may not fully preserve red blood cell (RBC) function during storage, contributing to the decrease of RBC oxygen release ability. This study was undertaken to evaluate the impact of routine cold storage on RBC oxygen release ability. RBC units were collected from healthy donors and each unit was split into two parts (whole blood and suspended RBC) to exclude possible donor variability. Oxygen dissociation measurements were performed on blood units stored at 4 °C during a 5-week period. 2,3-diphosphoglycerate levels and fluorescent micrographs of erythrocyte band 3 were also analysed. P50 and oxygen release capacity decreased rapidly during the first 3 weeks, and then did not change significantly. In contrast, the kinetic properties (PO2-t curve and T*50) of oxygen release changed slowly during the first 3 weeks of storage, but then decreased significantly in the last 2 weeks. 2,3-diphosphoglycerate decreased quickly during the first 3 weeks of storage to almost undetectable levels. Band 3 aggregated significantly during the last 2 weeks of storage. RBC oxygen release ability appears to be sensitive to routine cold storage. The thermodynamic characteristics of RBC oxygen release ability changed mainly in the first 3 weeks of storage, due to the decrease of 2,3-diphosphoglycerate, whereas the kinetic characteristics of RBC oxygen release ability decreased significantly at the end of storage, probably affected by alterations of band 3.

  2. Therapeutic effect of forearm low level light treatment on blood flow, oxygenation, and oxygen consumption

    Science.gov (United States)

    Wang, Pengbo; Sun, Jiajing; Meng, Lingkang; Li, Zebin; Li, Ting

    2018-02-01

    Low level light/laser therapy (LLLT) is considered as a novel, non-invasive, and potential therapy in a variety of psychological and physical conditions, due to its effective intricate photobiomodulation. The mechanism of LLLT is that when cells are stimulated by photons, mitochondria produce a large quantity of ATP, which accelerates biochemical responses in the cell. It is of great significance to gain a clear insight into the change or interplay of various physiological parameters. In this study, we used functional near-infrared spectroscopy (fNIRS) and venous-occlusion plethysmography to measure the LLLT-induced changes in blood flow, oxygenation, and oxygen consumption in human forearms in vivo. Six healthy human participants (4 males and 2 females) were administered with 810-nm light emitted by LED array in ten minutes and blood flow, oxygenation and oxygen consumption were detected in the entire experiment. We found that LLLT induced an increase of blood flow and oxygen consumption on the treated site. Meanwhile, LLLT took a good role in promoting oxygenation of regional tissue, which was indicated by a significant increase of oxygenated hemoglobin concentration (Δ[HbO2]), a nearly invariable deoxygenated hemoglobin concentration (Δ[Hb]) and a increase of differential hemoglobin concentration (Δ[HbD] = Δ[HbO2] - Δ[Hb]). These results not only demonstrate enormous potential of LLLT, but help to figure out mechanisms of photobiomodulation.

  3. A neural measure of behavioral engagement: task-residual low-frequency blood oxygenation level-dependent activity in the precuneus.

    Science.gov (United States)

    Zhang, Sheng; Li, Chiang-Shan Ray

    2010-01-15

    Brain imaging has provided a useful tool to examine the neural processes underlying human cognition. A critical question is whether and how task engagement influences the observed regional brain activations. Here we highlighted this issue and derived a neural measure of task engagement from the task-residual low-frequency blood oxygenation level-dependent (BOLD) activity in the precuneus. Using independent component analysis, we identified brain regions in the default circuit - including the precuneus and medial prefrontal cortex (mPFC) - showing greater activation during resting as compared to task residuals in 33 individuals. Time series correlations with the posterior cingulate cortex as the seed region showed that connectivity with the precuneus was significantly stronger during resting as compared to task residuals. We hypothesized that if the task-residual BOLD activity in the precuneus reflects engagement, it should account for a certain amount of variance in task-related regional brain activation. In an additional experiment of 59 individuals performing a stop signal task, we observed that the fractional amplitude of low-frequency fluctuation (fALFF) of the precuneus but not the mPFC accounted for approximately 10% of the variance in prefrontal activation related to attentional monitoring and response inhibition. Taken together, these results suggest that task-residual fALFF in the precuneus may be a potential indicator of task engagement. This measurement may serve as a useful covariate in identifying motivation-independent neural processes that underlie the pathogenesis of a psychiatric or neurological condition.

  4. Brain oxygen saturation assessment in neonates using T2-prepared blood imaging of oxygen saturation and near-infrared spectroscopy

    DEFF Research Database (Denmark)

    Alderliesten, Thomas; De Vis, Jill B; Lemmers, Petra Ma

    2017-01-01

    saturation in the sagittal sinus (R(2 )= 0.49, p = 0.023), but no significant correlations could be demonstrated with frontal and whole brain cerebral blood flow. These results suggest that measuring oxygen saturation by T2-prepared blood imaging of oxygen saturation is feasible, even in neonates. Strong...... sinus. A strong linear relation was found between the oxygen saturation measured by magnetic resonance imaging and the oxygen saturation measured by near-infrared spectroscopy (R(2 )= 0.64, p ..., and magnetic resonance imaging measures of frontal cerebral blood flow, whole brain cerebral blood flow and venous oxygen saturation in the sagittal sinus (R(2 )= 0.71, 0.50, 0.65; p 

  5. Oxygen Measurements in Liposome Encapsulated Hemoglobin

    Science.gov (United States)

    Phiri, Joshua Benjamin

    Liposome encapsulated hemoglobins (LEH's) are of current interest as blood substitutes. An analytical methodology for rapid non-invasive measurements of oxygen in artificial oxygen carriers is examined. High resolution optical absorption spectra are calculated by means of a one dimensional diffusion approximation. The encapsulated hemoglobin is prepared from fresh defibrinated bovine blood. Liposomes are prepared from hydrogenated soy phosphatidylcholine (HSPC), cholesterol and dicetylphosphate using a bath sonication method. An integrating sphere spectrophotometer is employed for diffuse optics measurements. Data is collected using an automated data acquisition system employing lock-in -amplifiers. The concentrations of hemoglobin derivatives are evaluated from the corresponding extinction coefficients using a numerical technique of singular value decomposition, and verification of the results is done using Monte Carlo simulations. In situ measurements are required for the determination of hemoglobin derivatives because most encapsulation methods invariably lead to the formation of methemoglobin, a nonfunctional form of hemoglobin. The methods employed in this work lead to high resolution absorption spectra of oxyhemoglobin and other derivatives in red blood cells and liposome encapsulated hemoglobin (LEH). The analysis using singular value decomposition method offers a quantitative means of calculating the fractions of oxyhemoglobin and other hemoglobin derivatives in LEH samples. The analytical methods developed in this work will become even more useful when production of LEH as a blood substitute is scaled up to large volumes.

  6. Improved arterial blood oxygenation following intravenous infusion of cold supersaturated dissolved oxygen solution.

    Science.gov (United States)

    Grady, Daniel J; Gentile, Michael A; Riggs, John H; Cheifetz, Ira M

    2014-01-01

    One of the primary goals of critical care medicine is to support adequate gas exchange without iatrogenic sequelae. An emerging method of delivering supplemental oxygen is intravenously rather than via the traditional inhalation route. The objective of this study was to evaluate the gas-exchange effects of infusing cold intravenous (IV) fluids containing very high partial pressures of dissolved oxygen (>760 mm Hg) in a porcine model. Juvenile swines were anesthetized and mechanically ventilated. Each animal received an infusion of cold (13 °C) Ringer's lactate solution (30 mL/kg/hour), which had been supersaturated with dissolved oxygen gas (39.7 mg/L dissolved oxygen, 992 mm Hg, 30.5 mL/L). Arterial blood gases and physiologic measurements were repeated at 15-minute intervals during a 60-minute IV infusion of the supersaturated dissolved oxygen solution. Each animal served as its own control. Five swines (12.9 ± 0.9 kg) were studied. Following the 60-minute infusion, there were significant increases in PaO2 and SaO2 (P < 0.05) and a significant decrease in PaCO2 (P < 0.05), with a corresponding normalization in arterial blood pH. Additionally, there was a significant decrease in core body temperature (P < 0.05) when compared to the baseline preinfusion state. A cold, supersaturated dissolved oxygen solution may be intravenously administered to improve arterial blood oxygenation and ventilation parameters and induce a mild therapeutic hypothermia in a porcine model.

  7. Noninvasive optical quantification of absolute blood flow, blood oxygenation, and oxygen consumption rate in exercising skeletal muscle

    Science.gov (United States)

    Gurley, Katelyn; Shang, Yu; Yu, Guoqiang

    2012-07-01

    This study investigates a method using novel hybrid diffuse optical spectroscopies [near-infrared spectroscopy (NIRS) and diffuse correlation spectroscopy (DCS)] to obtain continuous, noninvasive measurement of absolute blood flow (BF), blood oxygenation, and oxygen consumption rate (\\Vdot O2) in exercising skeletal muscle. Healthy subjects (n=9) performed a handgrip exercise to increase BF and \\Vdot O2 in forearm flexor muscles, while a hybrid optical probe on the skin surface directly monitored oxy-, deoxy-, and total hemoglobin concentrations ([HbO2], [Hb], and THC), tissue oxygen saturation (StO2), relative BF (rBF), and relative oxygen consumption rate (r\\Vdot O2). The rBF and r\\Vdot O2 signals were calibrated with absolute baseline BF and \\Vdot O2 obtained through venous and arterial occlusions, respectively. Known problems with muscle-fiber motion artifacts in optical measurements during exercise were mitigated using a novel gating algorithm that determined muscle contraction status based on control signals from a dynamometer. Results were consistent with previous findings in the literature. This study supports the application of NIRS/DCS technology to quantitatively evaluate hemodynamic and metabolic parameters in exercising skeletal muscle and holds promise for improving diagnosis and treatment evaluation for patients suffering from diseases affecting skeletal muscle and advancing fundamental understanding of muscle and exercise physiology.

  8. Blood transfusion in preterm infants improves intestinal tissue oxygenation without alteration in blood flow.

    Science.gov (United States)

    Banerjee, J; Leung, T S; Aladangady, N

    2016-11-01

    The objective of the study was to investigate the splanchnic blood flow velocity and oximetry response to blood transfusion in preterm infants according to postnatal age. Preterm infants receiving blood transfusion were recruited to three groups: 1-7 (group 1; n = 20), 8-28 (group 2; n = 21) and ≥29 days of life (group 3; n = 18). Superior mesenteric artery (SMA) peak systolic (PSV) and diastolic velocities were measured 30-60 min pre- and post-transfusion using Doppler ultrasound scan. Splanchnic tissue haemoglobin index (sTHI), tissue oxygenation index (sTOI) and fractional tissue oxygen extraction (sFTOE) were measured from 15-20 min before to post-transfusion using near-infrared spectroscopy. The mean pretransfusion Hb in group 1, 2 and 3 was 11, 10 and 9 g/dl, respectively. The mean (SD) pretransfusion SMA PSV in group 1, 2 and 3 was 0·63 (0·32), 0·81 (0·33) and 0·97 (0·40) m/s, respectively, and this did not change significantly following transfusion. The mean (SD) pretransfusion sTOI in group 1, 2 and 3 was 36·7 (19·3), 44·6 (10·4) and 41·3 (10·4)%, respectively. The sTHI and sTOI increased (P transfusion in all groups. On multivariate analysis, changes in SMA PSV and sTOI following blood transfusion were not associated with PDA, feeding, pretransfusion Hb and mean blood pressure. Pretransfusion baseline splanchnic tissue oximetry and blood flow velocity varied with postnatal age. Blood transfusion improved intestinal tissue oxygenation without altering mesenteric blood flow velocity irrespective of postnatal ages. © 2016 International Society of Blood Transfusion.

  9. Serial blood pressure measurements

    Directory of Open Access Journals (Sweden)

    N.R. Koehler

    2002-05-01

    Full Text Available The objective of the present investigation was to study the effects of a 60-s interval of venous congestion between two noninvasive measurements of arterial blood pressure (ABP on the fluctuation of ABP, assessed by the standard deviation of the differences between two readings. ABP was measured in 345 successive patients, at rest, four times each. For 269 participants, one pair of readings was obtained with a 60-s interval and the other pair without an interval. For 76 patients, the first pair was read at the same interval, and the second pair had venous congestion interposed and there was no waiting interval. There was no increased ABP oscillation, either when there was no interval between ABP readings, or when venous congestion was interposed compared to pairs of ABP measurements performed with a 60-s interval. There was no increase in ABP oscillations when successive ABP readings were taken without an interval or even with venous congestion interposed. Contrary to the present belief, there seems to be no loss of reliability when blood pressure recordings are taken immediately one after another, in the clinical setting.

  10. Cerebral blood flow and oxygen metabolism after subarachnoid hemorrhage

    International Nuclear Information System (INIS)

    Ito, Hidemichi; Sakurai, Takashi; Hayashi, Tatsuo; Hashimoto, Takuo

    2004-01-01

    The mechanism of reduction of cerebral circulation in the early phase of aneurysmal subarachnoid hemorrhage (SAH) has not yet been clarified. Previous studies have variously indicated that cerebral blood flow (CBF) reduction may be due to cerebral vasospasm, an elevation in intracranial pressure (ICP), constriction of intraparenchymal arterioles, or metabolic reduction. The aim of this study is to investigate the relationship between cerebral circulation and oxygen metabolism. In 36 patients with aneurysmal SAH, the values of mean cerebral blood flow (mCBF), cerebral metabolic rate of oxygen (GMRO 2 ) and oxygen extraction fraction (OEF) were measured by using single photon emission computed tomography (SPECT) with arterial blood drawing and oxygen saturation of internal jugular bulb blood (SjO 2 ) in the acute stage (1-3 days after onset) and the spasm stage (7-10 days after onset). The patients in our study were selected by using the following criteria: no history of cerebrovascular or cardiopulmonary diseases; under the age of 70; the ruptured aneurysm was treated by clipping or coil embolization within 72 hours after onset; no symptoms of cerebral vasospasm; no signs of cerebral ischemic change on CT scans. These patients were divided into 2 groups according to the World Federation of Neurological Surgeons (WFNS) grading classification; the mild group (Grades I and II) consisted of 27 cases and the severe group (Grade IV) consisted of 9 cases. We studied differences in mCBF CMRO 2 , and OEF between the mild group and severe group. In the mild group, mCBF, CMRO 2 , and OEF were significantly higher than in the severe group during both the acute and the spasm stage. Also mCBF showed a direct correlation with CMRO 2 . All the patients were kept under the following conditions: the bed was positioned so that the upper body was raised at an angle at 30 deg; blood pressure was maintained at 130-150 mmHg and PaCO 2 of arterial blood was maintained at 35-40 mmHg; ICP

  11. A blood-oxygenation-dependent increase in blood viscosity due to a static magnetic field

    International Nuclear Information System (INIS)

    Yamamoto, Toru; Nagayama, Yuki; Tamura, Mamoru

    2004-01-01

    As the magnetic field of widely used MR scanners is one of the strongest magnetic fields to which people are exposed, the biological influence of the static magnetic field of MR scanners is of great concern. One magnetic interaction in biological subjects is the magnetic torque on the magnetic moment induced by biomagnetic substances. The red blood cell is a major biomagnetic substance, and the blood flow may be influenced by the magnetic field. However, the underlying mechanisms have been poorly understood. To examine the mechanisms of the magnetic influence on blood viscosity, we measured the time for blood to fall through a glass capillary inside and outside a 1.5 T MR scanner. Our in vitro results showed that the blood viscosity significantly increased in a 1.5 T MR scanner, and also clarified the mechanism of the interaction between red blood cells and the external magnetic field. Notably, the blood viscosity increased depending on blood oxygenation and the shear rate of the blood flow. Thus, our findings suggest that even a 1.5 T magnetic field may modulate blood flow

  12. Relationship between retinal blood flow and arterial oxygen.

    Science.gov (United States)

    Cheng, Richard W; Yusof, Firdaus; Tsui, Edmund; Jong, Monica; Duffin, James; Flanagan, John G; Fisher, Joseph A; Hudson, Chris

    2016-02-01

    Vascular reactivity, the response of the vessels to a vasoactive stimulus such as hypoxia and hyperoxia, can be used to assess the vascular range of adjustment in which the vessels are able to compensate for changes in PO2. Previous studies in the retina have not accurately quantified retinal vascular responses and precisely targeted multiple PaO2 stimuli at the same time as controlling the level of carbon dioxide, thus precluding them from modelling the relationship between retinal blood flow and oxygen. The present study modelled the relationship between retinal blood flow and PaO2, showing them to be a combined linear and hyperbolic function. This model demonstrates that the resting tonus of the vessels is at the mid-point and that they have great vascular range of adjustment, compensating for decreases in oxygen above a PETCO2 of 32-37 mmHg but being limited below this threshold. Retinal blood flow (RBF) increases in response to a reduction in oxygen (hypoxia) but decreases in response to increased oxygen (hyperoxia). However, the relationship between blood flow and the arterial partial pressure of oxygen has not been quantified and modelled in the retina, particularly in the vascular reserve and resting tonus of the vessels. The present study aimed to determine the limitations of the retinal vasculature by modelling the relationship between RBF and oxygen. Retinal vascular responses were measured in 13 subjects for eight different blood gas conditions, with the end-tidal partial pressure of oxygen (PETCO2) ranging from 40-500 mmHg. Retinal vascular response measurements were repeated twice; using the Canon laser blood flowmeter (Canon Inc., Tokyo, Japan) during the first visit and using Doppler spectral domain optical coherence tomography during the second visit. We determined that the relationship between RBF and PaO2 can be modelled as a combination of hyperbolic and linear functions. We concluded that RBF compensated for decreases in arterial oxygen content

  13. Diffuse reflectance spectroscopy for the measurement of tissue oxygen saturation

    International Nuclear Information System (INIS)

    Sircan-Kucuksayan, A; Canpolat, M; Uyuklu, M

    2015-01-01

    Tissue oxygen saturation (StO 2 ) is a useful parameter for medical applications. A spectroscopic method has been developed to detect pathologic tissues, due to a lack of normal blood circulation, by measuring StO 2 . In this study, human blood samples with different levels of oxygen saturation have been prepared and spectra were acquired using an optical fiber probe to investigate the correlation between the oxygen saturation levels and the spectra. A linear correlation between the oxygen saturation and ratio of the intensities (760 nm to 790 nm) of the spectra acquired from blood samples has been found. In a validation study, oxygen saturations of the blood samples were estimated from the spectroscopic measurements with an error of 2.9%. It has also been shown that the linear dependence between the ratio and the oxygen saturation of the blood samples was valid for the blood samples with different hematocrits. Spectra were acquired from the forearms of 30 healthy volunteers to estimate StO 2 prior to, at the beginning of, after 2 min, and at the release of total vascular occlusion. The average StO 2 of a forearm before and after the two minutes occlusion was significantly different. The results suggested that optical reflectance spectroscopy is a sensitive method to estimate the StO 2 levels of human tissue. The technique developed to measure StO 2 has potential to detect ischemia in real time. (paper)

  14. Photoreactivity of the occipital cortex measured by functional magnetic resonance imaging-blood oxygenation level dependent in migraine patients and healthy volunteers: pathophysiological implications.

    Science.gov (United States)

    Martín, Helena; Sánchez del Río, Margarita; de Silanes, Carlos López; Álvarez-Linera, Juan; Hernández, Juan Antonio; Pareja, Juan A

    2011-01-01

    The brain of migraineurs is hyperexcitable, particularly the occipital cortex, which is probably hypersensitive to light. Photophobia or hypersensitivity to light may be accounted for by an increased excitability of trigeminal, the visual pathways, and the occipital cortex. To study light sensitivity and photophobia by assessing the response to light stimuli with functional magnetic resonance imaging-blood oxygenation level dependent (fMRI-BOLD) of the occipital cortex in migraineurs and in controls. Also, to try to decipher the contribution of the occipital cortex to photophobia and whether the cortical reactivity of migraineurs may be part of a constitutional (defensive) mechanism or represents an acquired (sensitization) phenomenon. Nineteen patients with migraine (7 with aura and 12 without aura) and 19 controls were studied with fMRI-BOLD during 4 increasing light intensities. Eight axial image sections of 0.5 cm that covered the occipital cortex were acquired for each intensity. We measured the extension and the intensity of activation for every light stimuli. Photophobia was estimated according to a 0 to 3 semiquantitative scale of light discomfort. Migraineurs had a significantly higher number of fMRI-activated voxels at low (320.4 for migraineurs [SD = 253.9] and 164.3 for controls [SD = 102.7], P = .027) and medium-low luminance levels (501.2 for migraineurs [SD = 279.5] and 331.1 for controls [SD = 194.3], P = .034) but not at medium-high (579.5 for migraineurs [SD = 201.4] and 510.2 for controls [SD = 239.5], P = .410) and high light stimuli (496.2 for migraineurs [SD = 216.2] and 394.7 for controls [SD = 240], P = .210). No differences were found with respect to the voxel activation intensity (amplitude of the BOLD wave) between migraineurs and controls (8.98 [SD = 2.58] vs 7.99 [SD = 2.57], P = .25; 10.82 [SD = 3.27] vs 9.81 [SD = 3.19], P = .31; 11.90 [SD = 3.18] vs 11.06 [SD = 2.56], P = .62; 11.45 [SD = 2.65] vs 10.25 [SD = 2.22], P = .16). Light

  15. Interleaved quantitative BOLD: Combining extravascular R2' - and intravascular R2-measurements for estimation of deoxygenated blood volume and hemoglobin oxygen saturation.

    Science.gov (United States)

    Lee, Hyunyeol; Englund, Erin K; Wehrli, Felix W

    2018-03-23

    Quantitative BOLD (qBOLD), a non-invasive MRI method for assessment of hemodynamic and metabolic properties of the brain in the baseline state, provides spatial maps of deoxygenated blood volume fraction (DBV) and hemoglobin oxygen saturation (HbO 2 ) by means of an analytical model for the temporal evolution of free-induction-decay signals in the extravascular compartment. However, mutual coupling between DBV and HbO 2 in the signal model results in considerable estimation uncertainty precluding achievement of a unique set of solutions. To address this problem, we developed an interleaved qBOLD method (iqBOLD) that combines extravascular R 2 ' and intravascular R 2 mapping techniques so as to obtain prior knowledge for the two unknown parameters. To achieve these goals, asymmetric spin echo and velocity-selective spin-labeling (VSSL) modules were interleaved in a single pulse sequence. Prior to VSSL, arterial blood and CSF signals were suppressed to produce reliable estimates for cerebral venous blood volume fraction (CBV v ) as well as venous blood R 2 (to yield HbO 2 ). Parameter maps derived from the VSSL module were employed to initialize DBV and HbO 2 in the qBOLD processing. Numerical simulations and in vivo experiments at 3 T were performed to evaluate the performance of iqBOLD in comparison to the parent qBOLD method. Data obtained in eight healthy subjects yielded plausible values averaging 60.1 ± 3.3% for HbO 2 and 3.1 ± 0.5 and 2.0 ± 0.4% for DBV in gray and white matter, respectively. Furthermore, the results show that prior estimates of CBV v and HbO 2 from the VSSL component enhance the solution stability in the qBOLD processing, and thus suggest the feasibility of iqBOLD as a promising alternative to the conventional technique for quantifying neurometabolic parameters. Copyright © 2018. Published by Elsevier Inc.

  16. Prefrontal blood flow and oxygenation measured by NIRS during long-term memory tasks are impaired by acute hyperglycemia (Conference Presentation)

    Science.gov (United States)

    Harris, R. Luke; Bell, Lindsay; Reimer, Andrea; Pettersen, Jacqueline A.; Siakaluk, Paul; Duffels, Brian

    2017-02-01

    Our goal was to use 2-channel frequency domain near-infrared spectroscopy (NIRS) to investigate the hemodynamic and metabolic mechanisms underlying hyperglycemia-associated long-term memory impairment. We hypothesized that prefrontal cortex (PFC) oxygen saturation (%Sat) and perfusion (tHb, i.e. total hemoglobin) would decrease due to hyperglycemia during learning, and then increase during recall. During learning, participants' blood glucose was manipulated with beverages containing either 47.4 mg saccharine control (CON, n = 10), or 50 g dextrose + 23.7 mg saccharine (GLC, n = 10). In the Symbol-Digit Modalities Test (SMDT) participants matched nine symbols to corresponding digits (1-9 inclusive), completing 105 learning and 15 testing trials on day 1 and 15 testing trials on day 2. From learning to recall, CON SMDT performance was unchanged, but GLC SMDT performance was decreased 11% (P = 0.0173). There were significant interactions (2-way ANOVA) between the CON-GLC treatment effects and the learning-recall effects for both PFC perfusion and oxygen saturation. Specifically, comparing learning to recall, CON exhibited no tHb differences but for GLC there was a large tHb decrease during learning with a partial recovery toward CON values during recall (P = 0.0012); and, comparing learning to recall, CON exhibited a large %Sat decrease but GLC exhibited a large %Sat increase (P = 0.021). We speculate that, during learning, after overnight fasting (CON) the PFC demands more hemodynamic and metabolic resources and "works" harder, but with readily available sugar (GLC) the PFC exhibits decreased "effort."

  17. Modeling of Cerebral Oxygen Transport Based on In vivo Microscopic Imaging of Microvascular Network Structure, Blood Flow, and Oxygenation.

    Science.gov (United States)

    Gagnon, Louis; Smith, Amy F; Boas, David A; Devor, Anna; Secomb, Timothy W; Sakadžić, Sava

    2016-01-01

    Oxygen is delivered to brain tissue by a dense network of microvessels, which actively control cerebral blood flow (CBF) through vasodilation and contraction in response to changing levels of neural activity. Understanding these network-level processes is immediately relevant for (1) interpretation of functional Magnetic Resonance Imaging (fMRI) signals, and (2) investigation of neurological diseases in which a deterioration of neurovascular and neuro-metabolic physiology contributes to motor and cognitive decline. Experimental data on the structure, flow and oxygen levels of microvascular networks are needed, together with theoretical methods to integrate this information and predict physiologically relevant properties that are not directly measurable. Recent progress in optical imaging technologies for high-resolution in vivo measurement of the cerebral microvascular architecture, blood flow, and oxygenation enables construction of detailed computational models of cerebral hemodynamics and oxygen transport based on realistic three-dimensional microvascular networks. In this article, we review state-of-the-art optical microscopy technologies for quantitative in vivo imaging of cerebral microvascular structure, blood flow and oxygenation, and theoretical methods that utilize such data to generate spatially resolved models for blood flow and oxygen transport. These "bottom-up" models are essential for the understanding of the processes governing brain oxygenation in normal and disease states and for eventual translation of the lessons learned from animal studies to humans.

  18. Biomedical sensor for transcutaneous oxygen measurements using thick film technology

    OpenAIRE

    Lam, Yu-Zhi (Liza)

    2003-01-01

    The measurement of the partial pressure of oxygen in arterial blood is essential for the analysis of a patient's respiratory condition. There are several commercially available methods and systems to measure this parameter transcutaneously. However, they tend to be cumbersome and costly. To overcome the disadvantages presented, a new type of sensor for transcutaneous blood gas measurement was investigated, employing thick film technology, which is an excellent technique to produce sensors in ...

  19. Blood oxygen saturation determined by transmission spectrophotometry of hemolyzed blood samples

    Science.gov (United States)

    Malik, W. M.

    1967-01-01

    Use of the Lambert-Beer Transmission Law determines blood oxygen saturation of hemolyzed blood samples. This simplified method is based on the difference in optical absorption properties of hemoglobin and oxyhemoglobin.

  20. Blood oxygen and carbon dioxide transport in man

    OpenAIRE

    McElderry, Linda A.

    1981-01-01

    The effect of long term domiciliary oxygen therapy on the position and shape of the oxygen dissociation curve, together with other haematologic variables such as 2,3- diphosphoglycerate (2,3-DPG), haemoglobin concentration, packed cell volume, mean corpuscular haemoglobin concentration, and arterial blood gas and pH values, has been studied in patients with chronic bronchitis. Twenty-six patients were randomly allocated to receive either no oxygen therapy or 15 hours p...

  1. Oxygen dissociation curves of whole blood from the Egyptian free ...

    African Journals Online (AJOL)

    Tadarida aegyptiaca (mean body mass 13.5 g) is a fast flying insectivorous bat that hunts in open areas for extended periods, covering extensive distances during its foraging bouts. Whole blood samples taken from the wing arteries were analysed for 2,3-diphosphoglyceric acid, oxygen affinity and pH. The mean oxygen ...

  2. A numerical two layer model for blood oxygenation in lungs

    International Nuclear Information System (INIS)

    Aminatai, A.

    2001-01-01

    In the modelling of the simultaneous transport of O 2 and CO 2 in the pulmonary circulation described in our earlier studies, the blood has been treated as a homogeneous layer of haemoglobin solution. Since the size of the erythrocyte is not negligible in comparison with that of the capillary, the blood can no longer be considered as a homogeneous fluid and hence, It is worthwhile to consider the blood flow as a two-phase flow consisting of cells and plasma. In the present study, the heterogeneous nature of blood has been proposed by considering the axial train model for the flow [whitmore (1967)], in order to analyze the effect of cell free plasma layer on the process of blood oxygenation in pulmonary capillaries. The proposed model consists of a core of suspended erythrocytes surrounded by a cell free plasma layer near the wall. The coupled system of convective diffusion equaions together with the physiologically relevant boundary, entrance and interface conditions is solved numerically by a four-point semi-implicit scheme to gether with a fixed point iterative technique. The distance traversed by the blood before getting fully oxygenated is computed. It is shown that the core haematocrit and the thickness of the cell depleted layer affect the oxygenation process significantly. It is found that (i) oxygen takes longest and carbondioxide is the fastest to attain equilibraton, (ii) the blood is completely oxygenated within one-fifth part of its transit and (iii) the rate of oxygenation is smaller in case of homogeneous model than that in heterogenous model in the capillary. Finally, the effect of various physiological parameters on the rate of oxygenation has been examined

  3. Evaluation of Renal Blood Flow and Oxygenation in CKD Using Magnetic Resonance Imaging.

    Science.gov (United States)

    Khatir, Dinah S; Pedersen, Michael; Jespersen, Bente; Buus, Niels H

    2015-09-01

    Animal studies suggest that progression of chronic kidney disease (CKD) is related to renal hypoxia. With renal blood supply determining oxygen delivery and sodium absorption being the main contributor to oxygen consumption, we describe the relationship between renal oxygenation, renal artery blood flow, and sodium absorption in patients with CKD and healthy controls. Cross-sectional study. 62 stable patients with CKD stages 3 to 4 (mean age, 61±13 [SD] years) and 24 age- and sex-matched controls. CKD versus control status. Renal artery blood flow, tissue oxygenation (relative changes in deoxyhemoglobin concentration of the renal medulla [MR2*] and cortex [CR2*]), and sodium absorption. Renal artery blood flow was determined by phase-contrast magnetic resonance imaging (MRI); MR2* and CR2* were determined by blood oxygen level-dependent MRI. Ultrafiltered and reabsorbed sodium were determined from measured glomerular filtration rate (mGFR) and 24-hour urine collections. mGFR in patients was 37% that of controls (36±15 vs 97±23 mL/min/1.73 m(2); P renal artery blood flow was 72% that of controls (319 vs 443 mL/min; P renal artery blood flow or sodium absorption. Increasing arterial blood oxygen tension by breathing 100% oxygen had very small effects on CR2*, but reduced MR2* in both groups. Only renal artery blood flow was determined and thus regional perfusion could not be related to CR2* or MR2*. In CKD, reductions of mGFR and reabsorbed sodium are more than double that of renal artery blood flow, whereas cortical and medullary oxygenation are within the range of healthy persons. Reduction in glomerular filtration fraction may prevent renal hypoxia in CKD. Copyright © 2015 National Kidney Foundation, Inc. Published by Elsevier Inc. All rights reserved.

  4. Acute effect of glucose on cerebral blood flow, blood oxygenation, and oxidative metabolism.

    Science.gov (United States)

    Xu, Feng; Liu, Peiying; Pascual, Juan M; Xiao, Guanghua; Huang, Hao; Lu, Hanzhang

    2015-02-01

    While it is known that specific nuclei of the brain, for example hypothalamus, contain glucose-sensing neurons thus their activity is affected by blood glucose level, the effect of glucose modulation on whole-brain metabolism is not completely understood. Several recent reports have elucidated the long-term impact of caloric restriction on the brain, showing that animals under caloric restriction had enhanced rate of tricarboxylic acid cycle (TCA) cycle flux accompanied by extended life span. However, acute effect of postprandial blood glucose increase has not been addressed in detail, partly due to a scarcity and complexity of measurement techniques. In this study, using a recently developed noninvasive MR technique, we measured dynamic changes in global cerebral metabolic rate of O2 (CMRO2 ) following a 50 g glucose ingestion (N = 10). A time dependent decrease in CMRO2 was observed, which was accompanied by a reduction in oxygen extraction fraction (OEF) with unaltered cerebral blood flow (CBF). At 40 min post-ingestion, the amount of CMRO2 reduction was 7.8 ± 1.6%. A control study without glucose ingestion was performed (N = 10), which revealed no changes in CMRO2 , CBF, or OEF, suggesting that the observations in the glucose study was not due to subject drowsiness or fatigue after staying inside the scanner. These findings suggest that ingestion of glucose may alter the rate of cerebral metabolism of oxygen in an acute setting. © 2014 Wiley Periodicals, Inc.

  5. Agreement between arterial partial pressure of carbon dioxide and saturation of hemoglobin with oxygen values obtained by direct arterial blood measurements versus noninvasive methods in conscious healthy and ill foals.

    Science.gov (United States)

    Wong, David M; Alcott, Cody J; Wang, Chong; Bornkamp, Jennifer L; Young, Jessica L; Sponseller, Brett A

    2011-11-15

    To determine agreement between indirect measurements of end-tidal partial pressure of carbon dioxide (PetCO(2)) and saturation of hemoglobin with oxygen as measured by pulse oximetry (SpO(2)) with direct measurements of PaCO(2) and calculated saturation of hemoglobin with oxygen in arterial blood (SaO(2)) in conscious healthy and ill foals. Validation study. 10 healthy and 21 ill neonatal foals. Arterial blood gas analysis was performed on healthy and ill foals examined at a veterinary teaching hospital to determine direct measurements of PaCO(2) and PaO(2) along with SaO(2). Concurrently, PetCO(2) was measured with a capnograph inserted into a naris, and SpO(2) was measured with a reflectance probe placed at the base of the tail. Paired values were compared by use of Pearson correlation coefficients, and level of agreement was assessed with the Bland-Altman method. Mean ± SD difference between PaCO(2) and PetCO(2) was 0.1 ± 5.0 mm Hg. There was significant strong correlation (r = 0.779) and good agreement between PaCO(2) and PetCO(2). Mean ± SD difference between SaO(2) and SpO(2) was 2.5 ± 3.5%. There was significant moderate correlation (r = 0.499) and acceptable agreement between SaO(2) and SpO(2). Both PetCO(2) obtained by use of nasal capnography and SpO(2) obtained with a reflectance probe are clinically applicable and accurate indirect methods of estimating and monitoring PaCO(2) and SaO(2) in neonatal foals. Indirect methods should not replace periodic direct measurement of corresponding parameters.

  6. Positron emission tomography in cerebrovascular disease: The relationship between regional cerebral blood flow, blood volume and oxygen metabolism

    Energy Technology Data Exchange (ETDEWEB)

    Herold, S.

    1985-03-01

    Positron emission tomography in cerebrovascular disease has demonstrated the importance of the relationship between regional cerebral blood flow and the cerebral metabolic activity. In acute stroke it has been found that within the first hours after the onset of symptoms cerebral blood flow in the affected area is more depressed than cerebral oxygen utilisation. This relative preservation of oxygen utilisation results from an increase in the oxygen extraction ratio far above its normal value. However, the oxygen extraction fraction subsequently falls in the following days indicating the transition from a situation of possibly reversible ischaemia to irreversible infarction. In patients with carotid occlusive disease an increase in the oxygen extraction ratio has been observed only in very few cases. It has been shown, however, that at an earlier stage the relationship between CBF and CBV (as CBF/CBV-ratio) provides a sensitive measure of diminished perfusion pressure which could be helpful for the selection of patients for EC-IC bypass surgery. In patients with sickle cell anaemia it has been found that oxygen delivery to the brain is maintained by an increase in cerebral blood flow, whereas the oxygen extraction ratio is not increased despite the presence of a low oxygen affinity haemoglobin. Preliminary observations in classical migraine suggest an ischaemic situation during the attack.

  7. Measurement of oxygen consumption during muscle flaccidity exercise by near-infrared spectroscopy

    Science.gov (United States)

    Fukuda, K.; Fukawa, Y.

    2013-03-01

    Quantitative measurement oxygen consumption in the muscles is important to evaluate the effect of the exercise. Near-infrared spectroscopy (NIRS) is a noninvasive method for measuring muscle oxygenation. However, measurement results are affected by blood volume change due to changes in the blood pressure. In order to evaluate changes in blood volume and to improve measurement accuracy, we proposed a calculation method of three-wavelength measurement with considering the scattering factor and the measurement with monitoring blood flow for measuring the temporal change of the oxygen concentration more precisely. We applied three-wavelength light source (680nm, 808nm and 830nm) for the continued wave measurement. Two detectors (targeted detector and the reference detector) were placed near the target muscle and apart from it. We measured the blood flow by controlling the intravascular pressure and the oxygen consumption with the handgrip exercise in the forearm. The measured results show that the scattering factor contains the artifact at the surface and the blood flow in the artery and the vein in the same phase. The artifact and the blood flow in the same phase are reduced from the oxygenated and the deoxygenated hemoglobin densities. Thus our proposed method is effective for reducing the influence of the artifact and the blood flow in the same phase from the oxygen consumption measurement. Further, it is shown that the oxygen consumption is measured more accurately by subtracting the blood flow measured by the reference detector.

  8. Oxygen activity measurements in simulated converter matte

    CSIR Research Space (South Africa)

    Tshilombo, KG

    2007-01-01

    Full Text Available to the composition of the gas atmosphere over the melt. The measured oxygen activity was generally close to that predicted by FactSage calculations. This indicates that such oxygen activity measurements could be useful to monitor iron removal during converting...

  9. Blood oxygenation level dependent (BOLD). Renal imaging. Concepts and applications; Blood Oxygenation Level Dependent (BOLD). Bildgebung der Nieren. Konzepte und Anwendungen

    Energy Technology Data Exchange (ETDEWEB)

    Nissen, Johanna C.; Haneder, Stefan; Schoenberg, Stefan O.; Michaely, Henrik J. [Heidelberg Univ. Medizinische Fakultaet Mannheim (Germany). Inst. fuer Klinische Radiologie und Nuklearmedizin; Mie, Moritz B.; Zoellner, Frank G. [Heidelberg Univ. Medizinische Fakultaet Mannheim (DE). Inst. fuer Computerunterstuetzte Klinische Medizin (CKM)

    2010-07-01

    Many renal diseases as well as several pharmacons cause a change in renal blood flow and/or renal oxygenation. The blood oxygenation level dependent (BOLD) imaging takes advantage of local field inhomogeneities and is based on a T2{sup *}-weighted sequence. BOLD is a non-invasive method allowing an estimation of the renal, particularly the medullary oxygenation, and an indirect measurement of blood flow without administration of contrast agents. Thus, effects of different drugs on the kidney and various renal diseases can be controlled and observed. This work will provide an overview of the studies carried out so far and identify ways how BOLD can be used in clinical studies. (orig.)

  10. Renal Blood Flow, Glomerular Filtration Rate, and Renal Oxygenation in Early Clinical Septic Shock.

    Science.gov (United States)

    Skytte Larsson, Jenny; Krumbholz, Vitus; Enskog, Anders; Bragadottir, Gudrun; Redfors, Bengt; Ricksten, Sven-Erik

    2018-06-01

    Data on renal hemodynamics, function, and oxygenation in early clinical septic shock are lacking. We therefore measured renal blood flow, glomerular filtration rate, renal oxygen consumption, and oxygenation in patients with early septic shock. Prospective comparative study. General and cardiothoracic ICUs. Patients with norepinephrine-dependent early septic shock (n = 8) were studied within 24 hours after arrival in the ICU and compared with postcardiac surgery patients without acute kidney injury (comparator group, n = 58). None. Data on systemic hemodynamics and renal variables were obtained during two 30-minute periods. Renal blood flow was measured by the infusion clearance of para-aminohippuric acid, corrected for renal extraction of para-aminohippuric acid. Renal filtration fraction was measured by renal extraction of chromium-51 labeled EDTA. Renal oxygenation was estimated from renal oxygen extraction. Renal oxygen delivery (-24%; p = 0.037) and the renal blood flow-to-cardiac index ratio (-21%; p = 0.018) were lower, renal vascular resistance was higher (26%; p = 0.027), whereas renal blood flow tended to be lower (-19%; p = 0.068) in the septic group. Glomerular filtration rate (-32%; p = 0.006) and renal sodium reabsorption (-29%; p = 0.014) were both lower in the septic group. Neither renal filtration fraction nor renal oxygen consumption differed significantly between groups. Renal oxygen extraction was significantly higher in the septic group (28%; p = 0.022). In the septic group, markers of tubular injury were elevated. In early clinical septic shock, renal function was lower, which was accompanied by renal vasoconstriction, a lower renal oxygen delivery, impaired renal oxygenation, and tubular sodium reabsorption at a high oxygen cost compared with controls.

  11. Effect of blood transfusion on intestinal blood flow and oxygenation in extremely preterm infants during first week of life.

    Science.gov (United States)

    Banerjee, Jayanta; Leung, Terence S; Aladangady, Narendra

    2016-04-01

    Extremely preterm infants receive frequent blood transfusions in the first week of life. The aim of this study was to measure the effect of blood transfusion on intestinal blood flow and oxygenation during the first week of life in extremely preterm infants. Superior mesenteric artery (SMA) peak systolic velocity (PSV) and diastolic velocities were measured 30 to 60 minutes before and after transfusion. Splanchnic tissue hemoglobin index (sTHI), splanchnic tissue oxygenation index (sTOI), and splanchnic fractional tissue oxygen extraction (sFTOE) were measured continuously from 15 to 20 minutes before to after transfusion along with vital variables. Twenty infants were studied (median gestational age, 26 weeks). Ten infants were partially fed (15-68 mL/kg/day). Heart rate and SaO2 remained unaltered; blood pressure increased significantly (p transfusion. Mean SMA PSV (p = 0.63) and diastolic velocity (p = 0.65) remained unaltered. Mean pretransfusion SMA PSV was similar in partially fed (0.78 m/sec) compared to unfed infants (0.52 m/sec; p = 0.06) and the response to transfusion was not dissimilar. There was a significant increase in sTHI (mean difference, 32.3%; p transfusion. There was no significant difference in sTHI or sTOI between fed and unfed infants and their response to transfusion. Blood transfusion increased blood pressure and intestinal tissue oxygenation but did not alter blood flow velocities. Partial feeding had no impact on intestinal blood flow and tissue oxygenation changes. © 2015 AABB.

  12. Methods of Blood Oxygen Level-Dependent Magnetic Resonance Imaging Analysis for Evaluating Renal Oxygenation

    Directory of Open Access Journals (Sweden)

    Fen Chen

    2018-03-01

    Full Text Available Blood oxygen level-dependent magnetic resonance imaging (BOLD MRI has recently been utilized as a noninvasive tool for evaluating renal oxygenation. Several methods have been proposed for analyzing BOLD images. Regional ROI selection is the earliest and most widely used method for BOLD analysis. In the last 20 years, many investigators have used this method to evaluate cortical and medullary oxygenation in patients with ischemic nephropathy, hypertensive nephropathy, diabetic nephropathy, chronic kidney disease (CKD, acute kidney injury and renal allograft rejection. However, clinical trials of BOLD MRI using regional ROI selection revealed that it was difficult to distinguish the renal cortico-medullary zones with this method, and that it was susceptible to observer variability. To overcome these deficiencies, several new methods were proposed for analyzing BOLD images, including the compartmental approach, fractional hypoxia method, concentric objects (CO method and twelve-layer concentric objects (TLCO method. The compartmental approach provides an algorithm to judge whether the pixel belongs to the cortex or medulla. Fractional kidney hypoxia, measured by using BOLD MRI, was negatively correlated with renal blood flow, tissue perfusion and glomerular filtration rate (GFR in patients with atherosclerotic renal artery stenosis. The CO method divides the renal parenchyma into six or twelve layers of thickness in each coronal slice of BOLD images and provides a R2* radial profile curve. The slope of the R2* curve associated positively with eGFR in CKD patients. Indeed, each method invariably has advantages and disadvantages, and there is generally no consensus method so far. Undoubtedly, analytic approaches for BOLD MRI with better reproducibility would assist clinicians in monitoring the degree of kidney hypoxia and thus facilitating timely reversal of tissue hypoxia.

  13. Oxygenation measurements in head and neck cancers during hyperbaric oxygenation

    International Nuclear Information System (INIS)

    Becker, A.; Kuhnt, T.; Dunst, J.; Liedtke, H.; Krivokuca, A.; Bloching, M.

    2002-01-01

    Background: Tumor hypoxia has proven prognostic impact in head and neck cancers and is associated with poor response to radiotherapy. Hyperbaric oxygenation (HBO) offers an approach to overcome hypoxia. We have performed pO 2 measurements in selected patients with head and neck cancers under HBO to determine in how far changes in the oxygenation occur and whether a possible improvement of oxygenation parameters is maintained after HBO. Patients and Methods: Seven patients (five male, two female, age 51-63 years) with squamous cell cancers of the head and neck were investigated (six primaries, one local recurrence). The median pO 2 prior to HBO was determined with the Eppendorf histograph. Sites of measurement were enlarged cervical lymph nodes (n = 5), the primary tumor (n = 1) and local recurrence (n = 1). Patients then underwent HBO (100% O 2 at 240 kPa for 30 minutes) and the continuous changes in the oxygenation during HBO were determined with a Licox probe. Patients had HBO for 30 minutes (n = 6) to 40 minutes (n = 1). HBO was continued because the pO 2 had not reached a steady state after 30 minutes. After decompression, patients ventilated pure oxygen under normobaric conditions and the course of the pO 2 was further measured over about 15 minutes. Results: Prior to HBO, the median tumor pO 2 in the Eppendorf histography was 8.6 ± 5.4 mm Hg (range 3-19 mm Hg) and the pO 2 measured with the Licox probe was 17.3 ± 25.5 mm Hg (range 0-73 mm Hg). The pO 2 increased significantly during HBO to 550 ± 333 mm Hg (range 85-984 mm Hg, p = 0.018). All patients showed a marked increase irrespective of the oxygenation prior to HBO. The maximum pO 2 in the tumor was reached after 10-33 minutes (mean 17 minutes). After leaving the hyperbaric chamber, the pO 2 was 282 ± 196 mm Hg. All patients maintained an elevated pO 2 for further 5-25 minutes (138 ± 128 mm Hg, range 42-334 mm Hg, p = 0.028 vs the pO 2 prior to HBO). Conclusions: Hyperbaric oxygenation resulted in a

  14. Monitoring of blood oxygenation in brain by resonance Raman spectroscopy

    DEFF Research Database (Denmark)

    Brazhe, Nadezda A; Thomsen, Kirsten; Lønstrup, Micael

    2018-01-01

    Blood oxygenation in cerebral vessels is an essential parameter to evaluate brain function and to investigate the coupling between local blood flow and neuronal activity. We apply resonance Raman spectroscopy in vivo to study hemoglobin oxygenation in cortex vessels of anesthetized ventilated mice....... We demonstrate that the pairs of Raman peaks at 1355 and1375 cm-1(symmetric vibrations of pyrrol half-rings in the heme molecule), 1552 and 1585 cm-1and 1602 and 1638 cm-1(vibrations of methine bridges in heme molecule) are reliable markers for quantitative estimation of the relative amount...

  15. Blood flow and oxygenation in peritendinous tissue and calf muscle during dynamic exercise in humans

    DEFF Research Database (Denmark)

    Boushel, Robert Christopher; Langberg, H; Green, Sara Marie Ehrenreich

    2000-01-01

    1. Circulation around tendons may act as a shunt for muscle during exercise. The perfusion and oxygenation of Achilles' peritendinous tissue was measured in parallel with that of calf muscle during exercise to determine (1) whether blood flow is restricted in peritendinous tissue during exercise......, and (2) whether blood flow is coupled to oxidative metabolism. 2. Seven individuals performed dynamic plantar flexion from 1 to 9 W. Radial artery and popliteal venous blood were sampled for O2, peritendinous blood flow was determined by 133Xe-washout, calf blood flow by plethysmography, cardiac output...

  16. Development of an oxygen saturation measuring system by using near-infrared spectroscopy

    Science.gov (United States)

    Kono, K.; Nakamachi, E.; Morita, Y.

    2017-08-01

    Recently, the hypoxia imaging has been recognized as the advanced technique to detect cancers because of a strong relationship with the biological characterization of cancer. In previous studies, hypoxia imaging systems for endoscopic diagnosis have been developed. However, these imaging technologies using the visible light can observe only blood vessels in gastric mucous membrane. Therefore, they could not detect scirrhous gastric cancer which accounts for 10% of all gastric cancers and spreads rapidly into submucous membrane. To overcome this problem, we developed a measuring system of blood oxygen saturation in submucous membrane by using near-infrared (NIR) spectroscopy. NIR, which has high permeability for bio-tissues and high absorbency for hemoglobin, can image and observe blood vessels in submucous membrane. NIR system with LED lights and a CCD camera module was developed to image blood vessels. We measured blood oxygen saturation using the optical density ratio (ODR) of two wavelengths, based on Lambert-Beer law. To image blood vessel clearly and measure blood oxygen saturation accurately, we searched two optimum wavelengths by using a multilayer human gastric-like phantom which has same optical properties as human gastric one. By using Monte Carlo simulation of light propagation, we derived the relationship between the ODR and blood oxygen saturation and elucidated the influence of blood vessel depth on measuring blood oxygen saturation. The oxygen saturation measuring methodology was validated with experiments using our NIR system. Finally, it was confirmed that our system can detect oxygen saturation in various depth blood vessels accurately.

  17. Optoacoustic technique for noninvasive monitoring of blood oxygenation: a feasibility study

    Science.gov (United States)

    Esenaliev, Rinat O.; Larina, Irina V.; Larin, Kirill V.; Deyo, Donald J.; Motamedi, Massoud; Prough, Donald S.

    2002-08-01

    Replacement of invasive monitoring of cerebral venous oxygenation with noninvasive techniques offers great promise in the management of life-threatening neurologic illnesses including traumatic brain injury. We developed and built an optoacoustic system to noninvasively monitor cerebral venous oxygenation; the system includes a nanosecond Nd:YAG laser and a specially designed optoacoustic probe. We tested the system in vitro in sheep blood with experimentally varied oxygenation. Our results demonstrated that (1) the amplitude and temporal profile of the optoacoustic waves increase with blood oxygenation in the range from 24% to 92%, (2) optoacoustic signals can be detected despite optical and acoustic attenuation by thick bone, and (3) the system is capable of real-time and continuous measurements. These results suggest that the optoacoustic technique is technically feasible for continuous, noninvasive monitoring of cerebral venous oxygenation.

  18. Measurement of biological oxygen demand sandy beaches

    African Journals Online (AJOL)

    Measurements of biological oxygen demand in a sandy beach using conventional .... counting the cells present in a sample of aged seawater and comparing this with .... This activity peaked at 71 % above the undisturbed level after 16 hours.

  19. Arterial blood oxygen saturation during blood pressure cuff-induced hypoperfusion

    International Nuclear Information System (INIS)

    Kyriacou, P A; Shafqat, K; Pal, S K

    2007-01-01

    Pulse oximetry has been one of the most significant technological advances in clinical monitoring in the last two decades. Pulse oximetry is a non-invasive photometric technique that provides information about the arterial blood oxygen saturation (SpO 2 ) and heart rate, and has widespread clinical applications. When peripheral perfusion is poor, as in states of hypovolaemia, hypothermia and vasoconstriction, oxygenation readings become unreliable or cease. The problem arises because conventional pulse oximetry sensors must be attached to the most peripheral parts of the body, such as finger, ear or toe, where pulsatile flow is most easily compromised. Pulse oximeters estimate arterial oxygen saturation by shining light at two different wavelengths, red and infrared, through vascular tissue. In this method the ac pulsatile photoplethysmographic (PPG) signal associated with cardiac contraction is assumed to be attributable solely to the arterial blood component. The amplitudes of the red and infrared ac PPG signals are sensitive to changes in arterial oxygen saturation because of differences in the light absorption of oxygenated and deoxygenated haemoglobin at these two wavelengths. From the ratios of these amplitudes, and the corresponding dc photoplethysmographic components, arterial blood oxygen saturation (SpO 2 ) is estimated. Hence, the technique of pulse oximetry relies on the presence of adequate peripheral arterial pulsations, which are detected as photoplethysmographic (PPG) signals. The aim of this study was to investigate the effect of pressure cuff-induced hypoperfusion on photoplethysmographic signals and arterial blood oxygen saturation using a custom made finger blood oxygen saturation PPG/SpO 2 sensor and a commercial finger pulse oximeter. Blood oxygen saturation values from the custom oxygen saturation sensor and a commercial finger oxygen saturation sensor were recorded from 14 healthy volunteers at various induced brachial pressures. Both pulse

  20. Arterial blood oxygen saturation during blood pressure cuff-induced hypoperfusion

    Energy Technology Data Exchange (ETDEWEB)

    Kyriacou, P A [School of Engineering and Mathematical Sciences, City University, London EC1V 0HB (United Kingdom); Shafqat, K [School of Engineering and Mathematical Sciences, City University, London EC1V 0HB (United Kingdom); Pal, S K [St Andrew' s Centre for Plastic Surgery and Burns, Broomfield Hospital, Chelmsford, CM1 7ET (United Kingdom)

    2007-10-15

    Pulse oximetry has been one of the most significant technological advances in clinical monitoring in the last two decades. Pulse oximetry is a non-invasive photometric technique that provides information about the arterial blood oxygen saturation (SpO{sub 2}) and heart rate, and has widespread clinical applications. When peripheral perfusion is poor, as in states of hypovolaemia, hypothermia and vasoconstriction, oxygenation readings become unreliable or cease. The problem arises because conventional pulse oximetry sensors must be attached to the most peripheral parts of the body, such as finger, ear or toe, where pulsatile flow is most easily compromised. Pulse oximeters estimate arterial oxygen saturation by shining light at two different wavelengths, red and infrared, through vascular tissue. In this method the ac pulsatile photoplethysmographic (PPG) signal associated with cardiac contraction is assumed to be attributable solely to the arterial blood component. The amplitudes of the red and infrared ac PPG signals are sensitive to changes in arterial oxygen saturation because of differences in the light absorption of oxygenated and deoxygenated haemoglobin at these two wavelengths. From the ratios of these amplitudes, and the corresponding dc photoplethysmographic components, arterial blood oxygen saturation (SpO{sub 2}) is estimated. Hence, the technique of pulse oximetry relies on the presence of adequate peripheral arterial pulsations, which are detected as photoplethysmographic (PPG) signals. The aim of this study was to investigate the effect of pressure cuff-induced hypoperfusion on photoplethysmographic signals and arterial blood oxygen saturation using a custom made finger blood oxygen saturation PPG/SpO{sub 2} sensor and a commercial finger pulse oximeter. Blood oxygen saturation values from the custom oxygen saturation sensor and a commercial finger oxygen saturation sensor were recorded from 14 healthy volunteers at various induced brachial pressures

  1. Arterial blood oxygen saturation during blood pressure cuff-induced hypoperfusion

    Science.gov (United States)

    Kyriacou, P. A.; Shafqat, K.; Pal, S. K.

    2007-10-01

    Pulse oximetry has been one of the most significant technological advances in clinical monitoring in the last two decades. Pulse oximetry is a non-invasive photometric technique that provides information about the arterial blood oxygen saturation (SpO2) and heart rate, and has widespread clinical applications. When peripheral perfusion is poor, as in states of hypovolaemia, hypothermia and vasoconstriction, oxygenation readings become unreliable or cease. The problem arises because conventional pulse oximetry sensors must be attached to the most peripheral parts of the body, such as finger, ear or toe, where pulsatile flow is most easily compromised. Pulse oximeters estimate arterial oxygen saturation by shining light at two different wavelengths, red and infrared, through vascular tissue. In this method the ac pulsatile photoplethysmographic (PPG) signal associated with cardiac contraction is assumed to be attributable solely to the arterial blood component. The amplitudes of the red and infrared ac PPG signals are sensitive to changes in arterial oxygen saturation because of differences in the light absorption of oxygenated and deoxygenated haemoglobin at these two wavelengths. From the ratios of these amplitudes, and the corresponding dc photoplethysmographic components, arterial blood oxygen saturation (SpO2) is estimated. Hence, the technique of pulse oximetry relies on the presence of adequate peripheral arterial pulsations, which are detected as photoplethysmographic (PPG) signals. The aim of this study was to investigate the effect of pressure cuff-induced hypoperfusion on photoplethysmographic signals and arterial blood oxygen saturation using a custom made finger blood oxygen saturation PPG/SpO2 sensor and a commercial finger pulse oximeter. Blood oxygen saturation values from the custom oxygen saturation sensor and a commercial finger oxygen saturation sensor were recorded from 14 healthy volunteers at various induced brachial pressures. Both pulse

  2. Meal-induced changes in splanchnic blood flow and oxygen uptake in middle-aged healthy humans

    DEFF Research Database (Denmark)

    Madsen, Jan Lysgård; Søndergaard, SB; Møller, Søren

    2006-01-01

    OBJECTIVE: For decades, the determination of changes in splanchnic blood flow and oxygen uptake after a meal has been used in the management of patients with suspected chronic intestinal ischaemia. However, little is known about the normal meal-induced responses. The aim of the present study...... was therefore to measure the splanchnic blood flow and oxygen uptake before and after a standardized meal in a group of middle-aged normal volunteers. MATERIAL AND METHODS: Splanchnic blood flow and oxygen uptake were determined at baseline and after a 3600-kJ mixed meal in 8 healthy women (50-70 years) and 10...... healthy men (52-76 years). Splanchnic blood flow was measured during hepatic vein catheterization by indirect Fick principle with indocyanine green as the indicator. Splanchnic oxygen uptake was calculated from splanchnic blood flow and the arteriovenous oxygen difference. RESULTS: The meal induced...

  3. Oxygen measurements in thin ribbon silicon

    Energy Technology Data Exchange (ETDEWEB)

    Hyland, S L; Ast, D G; Baghdadi, A

    1987-03-01

    The oxygen content of thin silicon ribbons grown by the dendritic web technique was measured using a modification of the ASTM method based on Fourier transform infrared spectroscopy. Web silicon was found to have a high oxygen content, ranging from 13 to 19 ppma, calculated from the absorption peak associated with interstitial oxygen and using the new ASTM conversion coefficient. The oxygen concentration changed by about 10% along the growth direction of the ribbon. In some samples, a shoulder was detected on the absorption peak. A similar shoulder in Czochralski grown material has been variously interpreted in the literature as due to a complex of silicon, oxygen, and vacancies, or to a phase of SiO/sub 2/ developed along dislocations in the material. In the case of web silicon, it is not clear which is the correct interpretation.

  4. Cerebral blood flow, oxygen and glucose metabolism with PET in progressive supranuclear palsy

    International Nuclear Information System (INIS)

    Otsuka, Makoto; Ichiya, Yuici; Kuwabara, Yasuo

    1989-01-01

    Cerebral blood flow, cerebral oxygen metabolic rate and cerebral glucose metabolic rate were measured with positron emission tomography (PET) in four patients with progressive supranuclear palsy (PSP). Decreased blood flow and hypometabolism of oxygen and glucose were found in both subcortical and cortical regions, particularly in the striatum including the head of the caudate nucleus and the frontal cortex. The coupling between blood flow and metabolism was preserved even in the regions which showed decreased blood flow and hypometabolism. These findings indicated the hypofunction, as revealed by decreased blood flow and hypometablolism on PET, both in the striatum and the frontal cortex, and which may underlie the pathophysiological mechanism of motor and mental disturbance in PSP. (author)

  5. Quantification of modulated blood oxygenation levels in single cerebral veins by investigating their MR signal decay

    Energy Technology Data Exchange (ETDEWEB)

    Sedlacik, Jan [St. Jude Children' s Research Hospital, Memphis, TN (United States). Div. of Translational Imaging Research; University Clinics Jena (Germany). Medical Physics Group; Rauscher, Alexander [University Clinics Jena (Germany). Medical Physics Group; British Columbia Univ., Vancouver (Canada). MRI Research Centre; Reichenbach, Juergen R. [University Clinics Jena (Germany). Medical Physics Group

    2009-07-01

    The transverse magnetization of a single vein and its surrounding tissue is subject to spin dephasing caused by the local magnetic field inhomogeneity which is induced by the very same vessel. This phenomenon can be approximated and simulated by applying the model of an infinitely long and homogeneously magnetized cylinder embedded in a homogeneous tissue background. It is then possible to estimate the oxygenation level of the venous blood by fitting the simulated magnetization-time-course to the measured signal decay. In this work we demonstrate the ability of this approach to quantify the blood oxygenation level (Y) of small cerebral veins in vivo, not only under normal physiologic conditions (Y{sub native}=0.5-0.55) but also during induced changes of physiologic conditions which affect the cerebral venous blood oxygenation level. Changes of blood's oxygenation level induced by carbogen (5% CO{sub 2}, 95% O{sub 2}) and caffeine were observed and quantified, resulting in values of Y{sub carbogen}=0.7 and Y{sub caffeine}=0.42, respectively. The proposed technique may ultimately help to better understand local changes in cerebral physiology during neuronal activation by quantifying blood oxygenation in veins draining active brain areas. It may also be beneficial in clinical applications where it may improve diagnosis of cerebral pathologies as well as monitoring of responses to therapy. (orig.)

  6. Society of cardiovascular anesthesiologists: the effect of blood pressure regulation during aortic coarctation repair on brain, kidney, and muscle oxygen saturation measured by near-infrared spectroscopy: a randomized, clinical trial

    NARCIS (Netherlands)

    Moerman, Annelies; Bové, Thierry; François, Katrien; Jacobs, Stefan; Deblaere, Isabel; Wouters, Patrick; de Hert, Stefan

    2013-01-01

    In this study, we compared the effects of 3 frequently used arterial blood pressure-regulating agents on brain (rScO2), renal (SrO2), and muscle (SmO2) oxygen saturation, during aortic coarctation repair in children. Based on the reported adverse effect of sodium nitroprusside (SNP) on left-sided

  7. Relationship between muscle oxygenation by NIRS and blood lactate

    Energy Technology Data Exchange (ETDEWEB)

    Xu Guodong [School of Physical Education, Jianghan University, Hubei Wuhan 430056 (China); Mao Zongzhen; Ye Yanjie; Lv Kunru, E-mail: xguodong@wipe.edu.cn [School of Health Sciences, Wuhan Institute of Physical Education, Hubei Wuhan 430079 (China)

    2011-01-01

    The aim of the study was to investigate the relationship of muscle oxygenation in term of oxy-hemoglobin concentration change ({Delta}HbO{sub 2}) by NIRS and blood lactate (BLA) in local skeletal muscle and evaluate the capability of NIRS in the research of exercise physiology Twenty-three athlete in the national fin-swimming team took the increasing load training on the power bicycle while their {Delta}HbO{sub 2} and BLA were simultaneously recorded. The initial powers used in the training were set as 100 w for males and 40 w for females. During the experiment, the power kept constant for 3 min before each abrupt increment of 30 w until the limit of the athlete's capability. Statistical analysis and data visualization were performed. Following the increasing load training, {Delta}HbO{sub 2} step-likely increased in the phase of aerobic metabolism but linearly decreased in the phase of anaerobic metabolism. The variation tendency of BLA was the same as {Delta}HbO{sub 2} and the concurrency of crucial turning points between {Delta}HbO{sub 2} and BLA was revealed. This relationship between {Delta}HbO{sub 2} and BLA presented in the increasing load training suggested that {Delta}HbO{sub 2} might be capable for taking the place of the invasively measured parameter BLA. Considering that {Delta}HbO{sub 2} can be noninvasively measured by NIRS, {Delta}HbO{sub 2} has the potential in the evaluation of athletes' physiological function and training effect on the athletes and accordingly NIRS can be well used in this field.

  8. Relationship between muscle oxygenation by NIRS and blood lactate

    International Nuclear Information System (INIS)

    Xu Guodong; Mao Zongzhen; Ye Yanjie; Lv Kunru

    2011-01-01

    The aim of the study was to investigate the relationship of muscle oxygenation in term of oxy-hemoglobin concentration change (ΔHbO 2 ) by NIRS and blood lactate (BLA) in local skeletal muscle and evaluate the capability of NIRS in the research of exercise physiology Twenty-three athlete in the national fin-swimming team took the increasing load training on the power bicycle while their ΔHbO 2 and BLA were simultaneously recorded. The initial powers used in the training were set as 100 w for males and 40 w for females. During the experiment, the power kept constant for 3 min before each abrupt increment of 30 w until the limit of the athlete's capability. Statistical analysis and data visualization were performed. Following the increasing load training, ΔHbO 2 step-likely increased in the phase of aerobic metabolism but linearly decreased in the phase of anaerobic metabolism. The variation tendency of BLA was the same as ΔHbO 2 and the concurrency of crucial turning points between ΔHbO 2 and BLA was revealed. This relationship between ΔHbO 2 and BLA presented in the increasing load training suggested that ΔHbO 2 might be capable for taking the place of the invasively measured parameter BLA. Considering that ΔHbO 2 can be noninvasively measured by NIRS, ΔHbO 2 has the potential in the evaluation of athletes' physiological function and training effect on the athletes and accordingly NIRS can be well used in this field.

  9. Cerebral oxygenation as measured by near-infrared spectroscopy in neonatal intensive care: correlation with arterial oxygenation.

    Science.gov (United States)

    Hunter, Carol Lu; Oei, Ju Lee; Lui, Kei; Schindler, Timothy

    2017-07-01

    To assess correlation between cerebral oxygenation (rScO 2 ), as measured by near-infrared spectroscopy (NIRS), and arterial oxygenation (PaO 2 ), as measured by arterial blood gases, in preterm neonates. Preterm neonates interpretation of NIRS values in neonatal intensive care, and further evaluation is needed to determine the applicability of NIRS to management of preterm infants. ©2017 Foundation Acta Paediatrica. Published by John Wiley & Sons Ltd.

  10. Effects of oxygenation and the stress hormones adrenaline and cortisol on the viscosity of blood from the trout oncorhynchus mykiss

    DEFF Research Database (Denmark)

    Sørensen, Bodil; Weber, Roy

    1995-01-01

    Although the concentrations of the stress hormones adrenaline and cortisol in rainbow trout (Oncorhynchus mykiss) blood increase upon hypoxic exposure, the combined effects of these hormones and O2 lack upon fish blood rheology have not been investigated. Deoxygenated blood taken by caudal puncture...... exhibited lower viscosities than oxygenated samples at low shear rates, whereas the opposite was true at high shear rates. However, blood from cannulated trout had similar viscosities in its deoxygenated and oxygenated states. In the deoxygenated state, addition of adrenaline lowered viscosity at low shear...... rates and increased it at high shear rates, resembling the effects of deoxygenation observed in blood taken by venepuncture. In oxygenated blood on the contrary, no marked adrenaline effects were observed. In deoxygenated blood, addition of cortisol lowered viscosity at all measured shear rates compared...

  11. Renal blood flow and oxygenation drive nephron progenitor differentiation.

    Science.gov (United States)

    Rymer, Christopher; Paredes, Jose; Halt, Kimmo; Schaefer, Caitlin; Wiersch, John; Zhang, Guangfeng; Potoka, Douglas; Vainio, Seppo; Gittes, George K; Bates, Carlton M; Sims-Lucas, Sunder

    2014-08-01

    During kidney development, the vasculature develops via both angiogenesis (branching from major vessels) and vasculogenesis (de novo vessel formation). The formation and perfusion of renal blood vessels are vastly understudied. In the present study, we investigated the regulatory role of renal blood flow and O2 concentration on nephron progenitor differentiation during ontogeny. To elucidate the presence of blood flow, ultrasound-guided intracardiac microinjection was performed, and FITC-tagged tomato lectin was perfused through the embryo. Kidneys were costained for the vasculature, ureteric epithelium, nephron progenitors, and nephron structures. We also analyzed nephron differentiation in normoxia compared with hypoxia. At embryonic day 13.5 (E13.5), the major vascular branches were perfused; however, smaller-caliber peripheral vessels remained unperfused. By E15.5, peripheral vessels started to be perfused as well as glomeruli. While the interior kidney vessels were perfused, the peripheral vessels (nephrogenic zone) remained unperfused. Directly adjacent and internal to the nephrogenic zone, we found differentiated nephron structures surrounded and infiltrated by perfused vessels. Furthermore, we determined that at low O2 concentration, little nephron progenitor differentiation was observed; at higher O2 concentrations, more differentiation of the nephron progenitors was induced. The formation of the developing renal vessels occurs before the onset of blood flow. Furthermore, renal blood flow and oxygenation are critical for nephron progenitor differentiation. Copyright © 2014 the American Physiological Society.

  12. Cerebral blood flow and oxygen metabolism in the Rett syndrome

    International Nuclear Information System (INIS)

    Yoshikawa, Hideto; Fueki, Noboru; Suzuki, Hisaharu; Sakuragawa, Norio; Iio, Masaaki

    1992-01-01

    Positron emission tomography (PET) was performed on six patients with the Rett syndrome and the results were compared with the concurrent clinical status of the patients. The cerebral metabolic rate of oxygen (CMRO 2 ) was low in five patients, and oxygen extraction fraction (OEF) was low in four patients; both had a tendency to decline with advancing age. Although the cause is unknown, it is suggested that impaired oxidative metabolism exists in the Rett syndrome. An analysis of the distribution among brain regions showed that the ratios of values for the frontal cortex to those for the temporal cortex for both the cerebral blood flow (CBF) and CMRO 2 were lower than those for the controls, which may indicate the loss of of hyperfrontality in the Rett syndrome. Distribution of brain metabolism may be immature in the Rett syndrome. (author)

  13. Effects of Hemoglobin-Based Oxygen Carriers on Blood Coagulation

    Directory of Open Access Journals (Sweden)

    Kimia Roghani

    2014-12-01

    Full Text Available For many decades, Hemoglobin-based oxygen carriers (HBOCs have been central in the development of resuscitation agents that might provide oxygen delivery in addition to simple volume expansion. Since 80% of the world population lives in areas where fresh blood products are not available, the application of these new solutions may prove to be highly beneficial (Kim and Greenburg 2006. Many improvements have been made to earlier generation HBOCs, but various concerns still remain, including coagulopathy, nitric oxide scavenging, platelet interference and decreased calcium concentration secondary to volume expansion (Jahr et al. 2013. This review will summarize the current challenges faced in developing HBOCs that may be used clinically, in order to guide future research efforts in the field.

  14. Automated Office Blood Pressure Measurement.

    Science.gov (United States)

    Myers, Martin G

    2018-04-01

    Manual blood pressure (BP) recorded in routine clinical practice is relatively inaccurate and associated with higher readings compared to BP measured in research studies in accordance with standardized measurement guidelines. The increase in routine office BP is the result of several factors, especially the presence of office staff, which tends to make patients nervous and also allows for conversation to occur. With the disappearance of the mercury sphygmomanometer because of environmental concerns, there is greater use of oscillometric BP recorders, both in the office setting and elsewhere. Although oscillometric devices may reduce some aspects of observer BP measurement error in the clinical setting, they are still associated with higher BP readings, known as white coat hypertension (for diagnosis) or white coat effect (with treated hypertension). Now that fully automated sphygmomanometers are available which are capable of recording several readings with the patient resting quietly, there is no longer any need to have office staff present when BP is being recorded. Such readings are called automated office blood pressure (AOBP) and they are both more accurate than conventional manual office BP and not associated with the white coat phenomena. AOBP readings are also similar to the awake ambulatory BP and home BP, both of which are relatively good predictors of cardiovascular risk. The available evidence suggests that AOBP should now replace manual or electronic office BP readings when screening patients for hypertension and also after antihypertensive drug therapy is initiated. Copyright © 2018. The Korean Society of Cardiology.

  15. Blood Transfusion Strategies in Patients Undergoing Extracorporeal Membrane Oxygenation

    Directory of Open Access Journals (Sweden)

    Hyoung Soo Kim

    2017-02-01

    Full Text Available Extracorporeal membrane oxygenation (ECMO is frequently associated with bleeding and coagulopathy complications, which may lead to the need for transfusion of multiple blood products. However, blood transfusions are known to increase morbidity and mortality, as well as hospital cost, in critically ill patients. In current practice, patients on ECMO receive a transfusion, on average, of 1-5 packed red blood cells (RBCs/day, with platelet transfusion accounting for the largest portion of transfusion volume. Generally, adult patients require more transfusions than neonates or children, and patients receiving venovenous ECMO for respiratory failure tend to need smaller transfusion volumes compared to those receiving venoarterial ECMO for cardiac failure. Observation studies have reported that a higher transfusion volume was associated with increased mortality. To date, the evidence for transfusion in patients undergoing ECMO is limited; most knowledge on transfusion strategies was extrapolated from studies in critically ill patients. However, current data support a restrictive blood transfusion strategy for ECMO patients, and a low transfusion trigger seems to be safe and reasonable.

  16. Cerebral blood flow and cerebral oxygen metabolism in thalamic hemorrhage

    International Nuclear Information System (INIS)

    Yasui, Nobuyuki; Asakura, Ken

    1987-01-01

    Cerebral blood flow (CBF), cerebral oxygen consumption (CMRO 2 ), oxygen extraction fraction (OEF) and cerebral blood volume (CBV) were studied in 20 cases of thalamic hemorrhage using positron CT and 15 O labeled gas steady-state inhalation method. CBF reduction was limited around the thalamus in the small sized hematoma. CBF were significantly diminished in the mean cortical, parietal, temporal, basal ganglia and thalamic area ipsilateral and cerebellar cortex contralateral to the medium sized hematoma. There was bilateral and diffuse CBF reduction in the large sized hematoma which was caused by increased intracranial pressure. CMRO 2 value were similary changed as CBF. OEF change showed within normal limit. Diffuse CBV reduction was observed in the large sized hematoma. This reduction was the result of decreased vascular bed caused by mass effect of the hematoma and hydrocephalus. Effect of surgical treatment such as ventricular drainage and hematoma evacuation were also discussed in correlation to CBF in some case using positron and single photon ECT. (author)

  17. Effects of Intensified Vasodilatory Antihypertensive Treatment on Renal Function, Blood supply and Oxygenation in Chronic Kidney Disease

    DEFF Research Database (Denmark)

    Khatir, Dinah Sherzad; Pedersen, Michael; Ivarsen, Per

    2015-01-01

    -blocker metoprolol). At baseline and following 18 months of therapy we determined forearm resistance by venous occlusion plethysmography. Using magnetic resonance imaging (MRI) renal artery blood flow was measured for calculation of RVR, and blood oxygen level dependent (BOLD) MRI was used as a marker of renal...

  18. Eigenspectra optoacoustic tomography achieves quantitative blood oxygenation imaging deep in tissues

    Science.gov (United States)

    Tzoumas, Stratis; Nunes, Antonio; Olefir, Ivan; Stangl, Stefan; Symvoulidis, Panagiotis; Glasl, Sarah; Bayer, Christine; Multhoff, Gabriele; Ntziachristos, Vasilis

    2016-06-01

    Light propagating in tissue attains a spectrum that varies with location due to wavelength-dependent fluence attenuation, an effect that causes spectral corruption. Spectral corruption has limited the quantification accuracy of optical and optoacoustic spectroscopic methods, and impeded the goal of imaging blood oxygen saturation (sO2) deep in tissues; a critical goal for the assessment of oxygenation in physiological processes and disease. Here we describe light fluence in the spectral domain and introduce eigenspectra multispectral optoacoustic tomography (eMSOT) to account for wavelength-dependent light attenuation, and estimate blood sO2 within deep tissue. We validate eMSOT in simulations, phantoms and animal measurements and spatially resolve sO2 in muscle and tumours, validating our measurements with histology data. eMSOT shows substantial sO2 accuracy enhancement over previous optoacoustic methods, potentially serving as a valuable tool for imaging tissue pathophysiology.

  19. Eigenspectra optoacoustic tomography achieves quantitative blood oxygenation imaging deep in tissues.

    Science.gov (United States)

    Tzoumas, Stratis; Nunes, Antonio; Olefir, Ivan; Stangl, Stefan; Symvoulidis, Panagiotis; Glasl, Sarah; Bayer, Christine; Multhoff, Gabriele; Ntziachristos, Vasilis

    2016-06-30

    Light propagating in tissue attains a spectrum that varies with location due to wavelength-dependent fluence attenuation, an effect that causes spectral corruption. Spectral corruption has limited the quantification accuracy of optical and optoacoustic spectroscopic methods, and impeded the goal of imaging blood oxygen saturation (sO2) deep in tissues; a critical goal for the assessment of oxygenation in physiological processes and disease. Here we describe light fluence in the spectral domain and introduce eigenspectra multispectral optoacoustic tomography (eMSOT) to account for wavelength-dependent light attenuation, and estimate blood sO2 within deep tissue. We validate eMSOT in simulations, phantoms and animal measurements and spatially resolve sO2 in muscle and tumours, validating our measurements with histology data. eMSOT shows substantial sO2 accuracy enhancement over previous optoacoustic methods, potentially serving as a valuable tool for imaging tissue pathophysiology.

  20. Measuring oxidation processes: Atomic oxygen flux monitor

    International Nuclear Information System (INIS)

    Anon.

    1991-01-01

    Of the existing 95 high-energy accelerators in the world, the Stanford Linear Collider (SLC) at the Stanford Linear Accelerator Center (SLAC) is the only one of the linear-collider type, where electrons and positrons are smashed together at energies of 50 GeV using linear beams instead of beam rings for achieving interactions. Use of a collider eliminates energy losses in the form of x-rays due to the curved trajectory of the rings, a phenomena known as bremsstrauhlung. Because these losses are eliminated, higher interaction energies are reached. Consequently the SLC produced the first Z particle in quantities large enough to allow measurement of its physical properties with some accuracy. SLAC intends to probe still deeper into the structure of matter by next polarizing the electrons in the beam. The surface of the source for these polarized particles, typically gallium arsenide, must be kept clean of contaminants. One method for accomplishing this task requires the oxidation of the surface, from which the oxidized contaminants are later boiled off. The technique requires careful measurement of the oxidation process. SLAC researchers have developed a technique for measuring the atomic oxygen flux in this process. The method uses a silver film on a quartz-crystal, deposition-rate monitor. Measuring the initial oxidation rate of the silver, which is proportional to the atomic oxygen flux, determines a lower limit on that flux in the range of 10 13 to 10 17 atoms per square centimeter per second. Furthermore, the deposition is reversible by exposing the sensor to atomic hydrogen. This technique has wider applications to processes in solid-state and surface physics as well as surface chemistry. In semiconductor manufacturing where a precise thickness of oxide must be deposited, this technique could be used to monitor the critical flux of atomic oxygen in the process

  1. Factors associated with blood oxygen partial pressure and carbon dioxide partial pressure regulation during respiratory extracorporeal membrane oxygenation support: data from a swine model.

    Science.gov (United States)

    Park, Marcelo; Mendes, Pedro Vitale; Costa, Eduardo Leite Vieira; Barbosa, Edzangela Vasconcelos Santos; Hirota, Adriana Sayuri; Azevedo, Luciano Cesar Pontes

    2016-01-01

    The aim of this study was to explore the factors associated with blood oxygen partial pressure and carbon dioxide partial pressure. The factors associated with oxygen - and carbon dioxide regulation were investigated in an apneic pig model under veno-venous extracorporeal membrane oxygenation support. A predefined sequence of blood and sweep flows was tested. Oxygenation was mainly associated with extracorporeal membrane oxygenation blood flow (beta coefficient = 0.036mmHg/mL/min), cardiac output (beta coefficient = -11.970mmHg/L/min) and pulmonary shunting (beta coefficient = -0.232mmHg/%). Furthermore, the initial oxygen partial pressure and carbon dioxide partial pressure measurements were also associated with oxygenation, with beta coefficients of 0.160 and 0.442mmHg/mmHg, respectively. Carbon dioxide partial pressure was associated with cardiac output (beta coefficient = 3.578mmHg/L/min), sweep gas flow (beta coefficient = -2.635mmHg/L/min), temperature (beta coefficient = 4.514mmHg/ºC), initial pH (beta coefficient = -66.065mmHg/0.01 unit) and hemoglobin (beta coefficient = 6.635mmHg/g/dL). In conclusion, elevations in blood and sweep gas flows in an apneic veno-venous extracorporeal membrane oxygenation model resulted in an increase in oxygen partial pressure and a reduction in carbon dioxide partial pressure 2, respectively. Furthermore, without the possibility of causal inference, oxygen partial pressure was negatively associated with pulmonary shunting and cardiac output, and carbon dioxide partial pressure was positively associated with cardiac output, core temperature and initial hemoglobin.

  2. The effect of glycerol on regional cerebral blood flow, blood volume and oxygen metabolism

    International Nuclear Information System (INIS)

    Ishikawa, Masatsune; Kikuchi, Haruhiko; Nagata, Izumi; Yamagata, Sen; Taki, Waro; Kobayashi, Akira; Yonekura, Yoshiharu; Nishizawa, Sadahiko.

    1989-01-01

    Using positron emission tomography with 15 O-labelled CO 2 , O 2 and CO gases, the effects of glycerol on regional cerebral blood flow (CBF), blood volume (CBV) and oxygen metabolism (CMRO 2 ) were investigated in 6 patients with meningioma accompanying peritumoral brain edema. The same study was done in 5 normal volunteers. The changes of blood gases, hematocrit and hemoglobin were also examined. After a drip infusion of glycerol, the regional CBF increased not only in the peritumoral cortex and white matter but also in the intact cortex and white matter on the contralateral side. The increase of CBF was extensive and substantially there were no regional differences. In contrast, the changes of CMRO 2 were not significant. This was derived from the increase in oxygen extraction fraction throughout extensive areas including the peritumoral area. There were no changes in CBV. Hematocrit and hemoglobin decreased to a small degree. In the normal volunteers, the same findings were noted. Thus, glycerol increases the functional reserve for cerebral oxygen metabolism, not only in the peritumoral regions but also in the intact regions. The effects of glycerol on hemodynamics and metabolism were discussed with reference to some differences from mannitol. (author)

  3. Blood gas analyzer utility in evaluating oxygen kinetics of the aqueous humor

    Directory of Open Access Journals (Sweden)

    Ismail Ersan

    2015-04-01

    Full Text Available Purpose: To measure the partial pressure of oxygen (PO2 and carbon dioxide (PCO2 and the pH of aqueous humor (AH and arterial blood samples from rabbits using a blood gas analyzer. Methods: Twenty New Zealand rabbits were anesthetized intramuscularly with ketamine and xylazine and were then allowed to breathe room air. Using a gas blood analyzer, arterial blood and AH samples were analyzed for PO2, PCO2, and pH. Results: The mean arterial blood pressure was 87.14 ± 15.0 mmHg. The mean blood and AH PO2 were 95.18 ± 11.76 mmHg and 88.83 ± 9.92 mmHg, the mean blood and AH PCO2 were 25.86 ± 5.46 mmHg and 29.50 ± 5.36 mmHg, and the mean blood and AH pH were 7.38 ± 0.06 and 7.33 ± 0.09, respectively. Conclusion: Conclusions: The blood gas analyzer was easily employed to evaluate the aqueous humor in rabbits. When comparing the results of studies evaluating aqueous PO2, care should be taken to determine the methods used in these studies.

  4. Myocardial oxygen extraction fraction measured using bolus inhalation of 15O-oxygen gas and dynamic PET

    NARCIS (Netherlands)

    Lubberink, Mark; Wong, YY; Raijmakers, P. G.; Huisman, Marc C.; Schuit, Robert C.; Luurtsema, Geert; Boellaard, Ronald; Knaapen, P; Vonk-Noordegraaf, Anton; Lammertsma, Adriaan A.

    Abstract The aim of this study was to determine the accuracy of oxygen extraction fraction (OEF) measurements using a dynamic scan protocol after bolus inhalation of 15O2. The method of analysis was optimized by investigating potential reuse of myocardial blood flow (MBF), perfusable tissue

  5. Validation of the Nonin 8600V Pulse Oximeter for heart rate and oxygen saturation measurements in rats.

    Science.gov (United States)

    Bernard, Susan L; An, Dowon; Glenny, Robb W

    2004-05-01

    This report validates the use and limitations of the Nonin Pulse Oximeter for measuring heart rate and oxygen saturation in rats. Eight anesthetized Sprague-Dawley rats were intubated and catheterized. Oxygen saturation was directly measured from arterial blood by using a Radiometer OSM3 Hemoximeter adjusted for rat blood as well as indirectly by using the Nonin Pulse Oximeter. Oxygen saturation was changed by varying the level of inhaled oxygen. Heart rate was measured in two ways: 1) by using the signal from the Nonin Pulse Oximeter and 2) by counting the pressure pulses from the transduced blood pressure. There was excellent agreement between heart rate values measured by the Nonin Pulse Oximeter and that measured by counting the pulses from the arterial blood pressure recording. The Nonin Pulse Oximeter underestimated oxygen saturations by about 3% to 5% compared to the Hemoximeter. Overall, the pulse oximeter reflected important trends in oxygen saturations, making it a useful tool for laboratory animal medicine.

  6. Noninvasive diffuse optical monitoring of head and neck tumor blood flow and oxygenation during radiation delivery

    Science.gov (United States)

    Dong, Lixin; Kudrimoti, Mahesh; Cheng, Ran; Shang, Yu; Johnson, Ellis L.; Stevens, Scott D.; Shelton, Brent J.; Yu, Guoqiang

    2012-01-01

    This study explored using a novel diffuse correlation spectroscopy (DCS) flow-oximeter to noninvasively monitor blood flow and oxygenation changes in head and neck tumors during radiation delivery. A fiber-optic probe connected to the DCS flow-oximeter was placed on the surface of the radiologically/clinically involved cervical lymph node. The DCS flow-oximeter in the treatment room was remotely operated by a computer in the control room. From the early measurements, abnormal signals were observed when the optical device was placed in close proximity to the radiation beams. Through phantom tests, the artifacts were shown to be caused by scattered x rays and consequentially avoided by moving the optical device away from the x-ray beams. Eleven patients with head and neck tumors were continually measured once a week over a treatment period of seven weeks, although there were some missing data due to the patient related events. Large inter-patient variations in tumor hemodynamic responses were observed during radiation delivery. A significant increase in tumor blood flow was observed at the first week of treatment, which may be a physiologic response to hypoxia created by radiation oxygen consumption. Only small and insignificant changes were found in tumor blood oxygenation, suggesting that oxygen utilizations in tumors during the short period of fractional radiation deliveries were either minimal or balanced by other effects such as blood flow regulation. Further investigations in a large patient population are needed to correlate the individual hemodynamic responses with the clinical outcomes for determining the prognostic value of optical measurements. PMID:22312579

  7. Blood pressure and anthropometric measurements in healthy ...

    African Journals Online (AJOL)

    Methods. We measured the blood pressures of 650 healthy, randomly ... In addition, blood pressure measurement should be a part of the routine clinical examination of children. ... familial risk factors.2 ... common cause of elevated blood pressure in children.4 They ... sphygmomanometer (Accoson, hospital model BS 274,.

  8. Oxygen affinity and Bohr effect responses to 2,3-diphosphoglycerate in equine and human blood.

    Science.gov (United States)

    diBella, G; Scandariato, G; Suriano, O; Rizzo, A

    1996-05-01

    The dependence of blood oxygen affinity and the Bohr effect on the concentration of 2,3-diphosphoglycerate (DPG) in erythrocytes was investigated in 24 trotter horses and 24 healthy men. The oxygen tension at half saturation and standard conditions (P50st at pH 7.4, PCO2(40) mmHg and 37 degrees C) and the carbon dioxide or fixed-acid-induced Bohr effect (dlogP50/dpH) were determined. Samples of fresh blood and blood depleted of or enriched with DPG were studied. In the absence of measurable DPG, the equine and human blood had similar mean (SD) values of P50st (16.6 [0.6] and 16.2 [0.7] mmHg, respectively). In both species these values increased with increasing DPG, but the response of equine blood was significantly lower, at least up to physiological values (P50st = 24.6 [0.6] and 26.2 [0.7]) mmHg; DPG = 14([1.8] and 12.8 [1.2] mumol gHb-1, respectively, in fresh blood). For concentrations above 20 to 25 mumol gHb-1 of DPG the difference between the values of P50st in the two species tended to decrease because the response in human blood reached a plateau. The interactions between the Bohr effect and the concentration of DPG showed that in the horses, as in the men, the level of DPG played an important role in governing the relative magnitude of carbon dioxide and fixed acid factors. The difference between them, which is associated with the oxylabile carbamino binding, was greatest in DPG-depleted blood, but whereas in the men the difference was suppressed by an above normal DPG concentration, in the horses it was still measurable.

  9. The effect of sensory stimulation provided by family on arterial blood oxygen saturation in critical care patients.

    Science.gov (United States)

    Yousefi, Hojatollah; Naderi, Mojgan; Daryabeigi, Reza

    2015-01-01

    Stressors in the intensive care unit (ICU) impair patients' comfort, excite the stress response, and increase oxygen consumption in their body. Non-medical interventions are recommended by several studies as a treatment to improve comfort in the ICU patients. Sensory stimulation is one of the most important interventions. Since arterial blood oxygen saturation is an important index of patients' clinical and respiratory condition, this study aimed to investigate the effect of sensory stimulation provided by family on arterial blood oxygen saturation in critical care patients. This study is a clinical trial conducted on 64 patients hospitalized in the ICU wards of Al-Zahra and Kashani hospitals in Isfahan, Iran in 2012 and 2013. The patients were selected by simple sampling method and were randomly assigned to two groups (study and control). Patients' arterial blood oxygen saturations were measured 10 min before, immediately after, 10 min and 30 min after sensory stimulation in the study group, and simultaneously in the control group without any intervention. Repeated measures analysis of variance (ANOVA) showed a significant difference in the mean of arterial blood oxygen saturation levels 10 min before, immediately after, 10 min and 30 min after sensory stimulation in the study group (P 0.18). Application of sensory stimulations as a nursing and non-medical intervention by the family members improves comfort and increases the level of blood oxygen saturation in critical care patients.

  10. Effects of exercise training on calf muscle oxygen extraction and blood flow in patients with peripheral artery disease.

    Science.gov (United States)

    Baker, Wesley B; Li, Zhe; Schenkel, Steven S; Chandra, Malavika; Busch, David R; Englund, Erin K; Schmitz, Kathryn H; Yodh, Arjun G; Floyd, Thomas F; Mohler, Emile R

    2017-12-01

    We employed near-infrared optical techniques, diffuse correlation spectroscopy (DCS), and frequency-domain near-infrared spectroscopy (FD-NIRS) to test the hypothesis that supervised exercise training increases skeletal muscle microvascular blood flow and oxygen extraction in patients with peripheral artery disease (PAD) who experience claudication. PAD patients ( n = 64) were randomly assigned to exercise and control groups. Patients in the exercise group received 3 mo of supervised exercise training. Calf muscle blood flow and oxygen extraction were optically monitored before, during, and after performance of a graded treadmill protocol at baseline and at 3 mo in both groups. Additionally, measurements of the ankle-brachial index (ABI) and peak walking time (PWT) to maximal claudication were made during each patient visit. Supervised exercise training was found to increase the maximal calf muscle blood flow and oxygen extraction levels during treadmill exercise by 29% (13%, 50%) and 8% (1%, 12%), respectively [ P group population were significantly higher than corresponding changes in the control group ( P training also increased PWT by 49% (18%, 101%) ( P = 0.01). However, within statistical error, the ABI, resting calf muscle blood flow and oxygen extraction, and the recovery half-time for hemoglobin\\myoglobin desaturation following cessation of maximal exercise were not altered by exercise training. The concurrent monitoring of both blood flow and oxygen extraction with the hybrid DCS/FD-NIRS instrument revealed enhanced muscle oxidative metabolism during physical activity from exercise training, which could be an underlying mechanism for the observed improvement in PWT. NEW & NOTEWORTHY We report on noninvasive optical measurements of skeletal muscle blood flow and oxygen extraction dynamics before/during/after treadmill exercise in peripheral artery disease patients who experience claudication. The measurements tracked the effects of a 3-mo supervised

  11. Measurement of oxygen transfer from air into organic solvents

    DEFF Research Database (Denmark)

    Ramesh, Hemalata; Mayr, Torsten; Hobisch, Mathias

    2016-01-01

    biological reactions require the supply of oxygen, most normally from air. However, reliable on-line measurements of oxygen concentration in organic solvents (and hence oxygen transfer rates from air to the solvent) has to date proven impossible due limitations in the current analytical methods. Results...... applications). Subsequently, we measured the oxygen transfer rates from air into these organic solvents. Conclusion The measurement of oxygen transfer rates from air into organic solvents using the dynamic method was established using the solvent resistant optical sensor. The feasibility of online oxygen...... For the first time, we demonstrate on-line oxygen measurements in non-aqueous media using a novel optical sensor. The sensor was used to measure oxygen concentration in various organic solvents including toluene, THF, isooctane, DMF, heptane and hexane (which have all been shown suitable for several biological...

  12. Photoplethysmography for blood volumes and oxygenation changes during intermittent vascular occlusions.

    Science.gov (United States)

    Abay, T Y; Kyriacou, P A

    2018-06-01

    Photoplethysmography (PPG) is an optical technique that measures blood volume variations. The main application of dual-wavelength PPG is pulse oximetry, in which the arterial oxygen saturation (SpO[Formula: see text]) is calculated noninvasively. However, the PPG waveform contains other significant physiological information that can be used in conjunction to SpO[Formula: see text] for the assessment of oxygenation and blood volumes changes. This paper investigates the use of near infrared spectroscopy (NIRS) processing techniques for extracting relative concentration changes of oxygenated ([Formula: see text]HbO[Formula: see text]), reduced ([Formula: see text]HHb) and total haemoglobin ([Formula: see text]tHb) from dual-wavelength PPG signals during intermittent pressure-increasing vascular occlusions. A reflectance PPG sensor was attached on the left forearm of nineteen (n = 19) volunteers, along with a reference NIRS sensor positioned on the same forearm, above the left brachioradialis. The investigation protocol consisted of seven intermittent and pressure-increasing vascular occlusions. Relative changes in haemoglobin concentrations were obtained by applying the modified Beer-Lambert law to PPG signals, while oxygenation changes were estimated by the difference between red and infrared attenuations of DC PPGs (A[Formula: see text] = [Formula: see text]A[Formula: see text] - [Formula: see text]A[Formula: see text]) and by the conventional SpO[Formula: see text]. The [Formula: see text]HbO[Formula: see text], [Formula: see text]HHb, [Formula: see text]tHb from the PPG signals indicated significant changes in perfusion induced by either partial and complete occlusions (p < 0.05). The trends in the variables extracted from PPG showed good correlation with the same parameters measured by the reference NIRS monitor. Bland and Altman analysis of agreement between PPG and NIRS showed underestimation of the magnitude of changes by the PPG. A[Formula: see text

  13. Quantitative Measurement of Oxygen in Microgravity Combustion

    Science.gov (United States)

    Silver, Joel A.

    1997-01-01

    A low-gravity environment, in space or in ground-based facilities such as drop towers, provides a unique setting for studying combustion mechanisms. Understanding the physical phenomena controlling the ignition and spread of flames in microgravity has importance for space safety as well as for better characterization of dynamical and chemical combustion processes which are normally masked by buoyancy and other gravity-related effects. Due to restrictions associated with performing measurements in reduced gravity, diagnostic methods which have been applied to microgravity combustion studies have generally been limited to capture of flame emissions on film or video, laser Schlieren imaging and (intrusive) temperature measurements using thermocouples. Given the development of detailed theoretical models, more sophisticated diagnostic methods are needed to provide the kind of quantitative data necessary to characterize the properties of microgravity combustion processes as well as provide accurate feedback to improve the predictive capabilities of the models. When the demands of space flight are considered, the need for improved diagnostic systems which are rugged, compact, reliable, and operate at low power becomes apparent. The objective of this research is twofold. First, we want to develop a better understanding of the relative roles of diffusion and reaction of oxygen in microgravity combustion. As the primary oxidizer species, oxygen plays a major role in controlling the observed properties of flames, including flame front speed (in solid or liquid flames), extinguishment characteristics, flame size and flame temperature. The second objective is to develop better diagnostics based on diode laser absorption which can be of real value in both microgravity combustion research and as a sensor on-board Spacelab as either an air quality monitor or as part of a fire detection system. In our prior microgravity work, an eight line-of-sight fiber optic system measured

  14. Blood oxygen transport in common map turtles during simulated hibernation.

    Science.gov (United States)

    Maginniss, Leigh A; Ekelund, Summer A; Ultsch, Gordon R

    2004-01-01

    We assessed the effects of cold and submergence on blood oxygen transport in common map turtles (Graptemys geographica). Winter animals were acclimated for 6-7 wk to one of three conditions at 3 degrees C: air breathing (AB-3 degrees C), normoxic submergence (NS-3 degrees C), and hypoxic (PO2=49 Torr) submergence (HS-3 degrees C). NS-3 degrees C turtles exhibited a respiratory alkalosis (pH 8.07; PCO2=7.9 Torr; [lactate]=2.2 mM) relative to AB-3 degrees C animals (pH 7.89; PCO2=13.4 Torr; [lactate]=1.1 mM). HS-3 degrees C animals experienced a profound metabolic acidosis (pH 7.30; PCO2=7.9 Torr; [lactate]=81 mM). NS-3 degrees C turtles exhibited an increased blood O2 capacity; however, isoelectric focusing revealed no seasonal changes in the isohemoglobin (isoHb) profile. Blood O2 affinity was significantly increased by cold acclimation; half-saturation pressures (P50's) for air-breathing turtles at 3 degrees and 22 degrees C were 6.5 and 18.8 Torr, respectively. P50's for winter animals submerged in normoxic and hypoxic water were 5.2 and 6.5 Torr, respectively. CO2 Bohr slopes (Delta logP50/Delta pH) were -0.15, -0.16, and -0.07 for AB-3 degrees C, NS-3 degrees C, and HS-3 degrees C turtles, respectively; the corresponding value for AB-22 degrees C was -0.37. The O2 equilibrium curve (O2EC) shape was similar for AB-3 degrees C and NS-3 degrees C turtles; Hill plot n coefficients ranged from 1.8 to 2.0. The O2EC shape for HS-3 degrees C turtles was anomalous, exhibiting high O2 affinity below P50 and a right-shifted segment above half-saturation. We suggest that increases in Hb-O2 affinity and O2 capacity enhance extrapulmonary O2 uptake by turtles overwintering in normoxic water. The anomalous O2EC shape and reduced CO2 Bohr effect of HS-3 degrees C turtles may also promote some aerobic metabolism in hypoxic water.

  15. BLOOD COMPATIBILITY OF 2 DIFFERENT TYPES OF MEMBRANE-OXYGENATOR DURING CARDIOPULMONARY BYPASS IN INFANTS

    NARCIS (Netherlands)

    GU, YJ; BOONSTRA, PW; AKKERMAN, C; MUNGROOP, H; TIGCHELAAR, [No Value; VANOEVEREN, W

    1994-01-01

    The contact of blood with the artificial extracorporeal circuit causes a systemic inflammatory response due to blood activation. In this study, we compared two different paediatric membrane oxygenators used for extracorporeal circulation: a hollow fibre membrane oxygenator (Dideco Masterflo D-701,

  16. Oxygen consumption and blood flow coupling in human motor cortex during intense finger tapping

    DEFF Research Database (Denmark)

    Seyedi Vafaee, Manouchehr; Vang, Kim; Bergersen, Linda H

    2012-01-01

    Rates of cerebral blood flow (CBF) and glucose consumption (CMR(glc)) rise in cerebral cortex during continuous stimulation, while the oxygen-glucose index (OGI) declines as an index of mismatched coupling of oxygen consumption (cerebral metabolic rate of oxygen-CMRO(2)) to CBF and CMR(glc). To t...

  17. The Effects of Acutely Administered 3,4-Methylenedioxymethamphetamine on Spontaneous Brain Function in Healthy Volunteers Measured with Arterial Spin Labeling and Blood Oxygen Level–Dependent Resting State Functional Connectivity

    Science.gov (United States)

    Carhart-Harris, Robin L.; Murphy, Kevin; Leech, Robert; Erritzoe, David; Wall, Matthew B.; Ferguson, Bart; Williams, Luke T.J.; Roseman, Leor; Brugger, Stefan; De Meer, Ineke; Tanner, Mark; Tyacke, Robin; Wolff, Kim; Sethi, Ajun; Bloomfield, Michael A.P.; Williams, Tim M.; Bolstridge, Mark; Stewart, Lorna; Morgan, Celia; Newbould, Rexford D.; Feilding, Amanda; Curran, H. Val; Nutt, David J.

    2015-01-01

    Background The compound 3,4-methylenedioxymethamphetamine (MDMA) is a potent monoamine releaser that produces an acute euphoria in most individuals. Methods In a double-blind, placebo-controlled, balanced-order study, MDMA was orally administered to 25 physically and mentally healthy individuals. Arterial spin labeling and seed-based resting state functional connectivity (RSFC) were used to produce spatial maps displaying changes in cerebral blood flow (CBF) and RSFC after MDMA administration. Participants underwent two arterial spin labeling and two blood oxygen level–dependent scans in a 90-minute scan session; MDMA and placebo study days were separated by 1 week. Results Marked increases in positive mood were produced by MDMA. Decreased CBF only was observed after MDMA, and this was localized to the right medial temporal lobe (MTL), thalamus, inferior visual cortex, and the somatosensory cortex. Decreased CBF in the right amygdala and hippocampus correlated with ratings of the intensity of global subjective effects of MDMA. The RSFC results complemented the CBF results, with decreases in RSFC between midline cortical regions, the medial prefrontal cortex, and MTL regions, and increases between the amygdala and hippocampus. There were trend-level correlations between these effects and ratings of intense and positive subjective effects. Conclusions The MTLs appear to be specifically implicated in the mechanism of action of MDMA, but further work is required to elucidate how the drug’s characteristic subjective effects arise from its modulation of spontaneous brain activity. PMID:24495461

  18. The Effects of Acutely Administered 3,4-Methylenedioxymethamphetamine on Spontaneous Brain Function in Healthy Volunteers Measured with Arterial Spin Labeling and Blood Oxygen Level-Dependent Resting State Functional Connectivity.

    Science.gov (United States)

    Carhart-Harris, Robin L; Murphy, Kevin; Leech, Robert; Erritzoe, David; Wall, Matthew B; Ferguson, Bart; Williams, Luke T J; Roseman, Leor; Brugger, Stefan; De Meer, Ineke; Tanner, Mark; Tyacke, Robin; Wolff, Kim; Sethi, Ajun; Bloomfield, Michael A P; Williams, Tim M; Bolstridge, Mark; Stewart, Lorna; Morgan, Celia; Newbould, Rexford D; Feilding, Amanda; Curran, H Val; Nutt, David J

    2015-10-15

    The compound 3,4-methylenedioxymethamphetamine (MDMA) is a potent monoamine releaser that produces an acute euphoria in most individuals. In a double-blind, placebo-controlled, balanced-order study, MDMA was orally administered to 25 physically and mentally healthy individuals. Arterial spin labeling and seed-based resting state functional connectivity (RSFC) were used to produce spatial maps displaying changes in cerebral blood flow (CBF) and RSFC after MDMA administration. Participants underwent two arterial spin labeling and two blood oxygen level-dependent scans in a 90-minute scan session; MDMA and placebo study days were separated by 1 week. Marked increases in positive mood were produced by MDMA. Decreased CBF only was observed after MDMA, and this was localized to the right medial temporal lobe (MTL), thalamus, inferior visual cortex, and the somatosensory cortex. Decreased CBF in the right amygdala and hippocampus correlated with ratings of the intensity of global subjective effects of MDMA. The RSFC results complemented the CBF results, with decreases in RSFC between midline cortical regions, the medial prefrontal cortex, and MTL regions, and increases between the amygdala and hippocampus. There were trend-level correlations between these effects and ratings of intense and positive subjective effects. The MTLs appear to be specifically implicated in the mechanism of action of MDMA, but further work is required to elucidate how the drug's characteristic subjective effects arise from its modulation of spontaneous brain activity. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

  19. Systematic instrumental errors between oxygen saturation analysers in fetal blood during deep hypoxemia.

    Science.gov (United States)

    Porath, M; Sinha, P; Dudenhausen, J W; Luttkus, A K

    2001-05-01

    During a study of artificially produced deep hypoxemia in fetal cord blood, systematic errors of three different oxygen saturation analysers were evaluated against a reference CO oximeter. The oxygen tensions (PO2) of 83 pre-heparinized fetal blood samples from umbilical veins were reduced by tonometry to 1.3 kPa (10 mm Hg) and 2.7 kPa (20 mm Hg). The oxygen saturation (SO2) was determined (n=1328) on a reference CO oximeter (ABL625, Radiometer Copenhagen) and on three tested instruments (two CO oximeters: Chiron865, Bayer Diagnostics; ABL700, Radiometer Copenhagen, and a portable blood gas analyser, i-STAT, Abbott). The CO oximeters measure the oxyhemoglobin and the reduced hemoglobin fractions by absorption spectrophotometry. The i-STAT system calculates the oxygen saturation from the measured pH, PO2, and PCO2. The measurements were performed in duplicate. Statistical evaluation focused on the differences between duplicate measurements and on systematic instrumental errors in oxygen saturation analysis compared to the reference CO oximeter. After tonometry, the median saturation dropped to 32.9% at a PO2=2.7 kPa (20 mm Hg), defined as saturation range 1, and to 10% SO2 at a PO2=1.3 kPa (10 mm Hg), defined as range 2. With decreasing SO2, all devices showed an increased difference between duplicate measurements. ABL625 and ABL700 showed the closest agreement between instruments (0.25% SO2 bias at saturation range 1 and -0.33% SO2 bias at saturation range 2). Chiron865 indicated higher saturation values than ABL 625 (3.07% SO2 bias at saturation range 1 and 2.28% SO2 bias at saturation range 2). Calculated saturation values (i-STAT) were more than 30% lower than the measured values of ABL625. The disagreement among CO oximeters was small but increasing under deep hypoxemia. Calculation found unacceptably low saturation.

  20. Determination of blood oxygenation in the brain by time-resolved reflectance spectroscopy: influence of the skin, skull, and meninges

    Science.gov (United States)

    Hielscher, Andreas H.; Liu, Hanli; Wang, Lihong; Tittel, Frank K.; Chance, Britton; Jacques, Steven L.

    1994-07-01

    Near infrared light has been used for the determination of blood oxygenation in the brain but little attention has been paid to the fact that the states of blood oxygenation in arteries, veins, and capillaries differ substantially. In this study, Monte Carlo simulations for a heterogeneous system were conducted, and near infrared time-resolved reflectance measurements were performed on a heterogeneous tissue phantom model. The model was made of a solid polyester resin, which simulates the tissue background. A network of tubes was distributed uniformly through the resin to simulate the blood vessels. The time-resolved reflectance spectra were taken with different absorbing solutions filled in the network. Based on the simulation and experimental results, we investigated the dependence of the absorption coefficient obtained from the heterogeneous system on the absorption of the actual absorbing solution filled in the tubes. We show that light absorption by the brain should result from the combination of blood and blood-free tissue background.

  1. Differences in prefrontal blood oxygenation during an acute multitasking stressor in ecstasy polydrug users.

    Science.gov (United States)

    Roberts, C A; Wetherell, M A; Fisk, J E; Montgomery, C

    2015-01-01

    Cognitive deficits are well documented in ecstasy (3,4-methylenedioxymethamphetamine; MDMA) users, with such deficits being taken as evidence of dysregulation of the serotonin (5-hydroxytryptamine; 5-HT) system. More recently neuroimaging has been used to corroborate these deficits. The present study aimed to assess multitasking performance in ecstasy polydrug users, polydrug users and drug-naive individuals. It was predicted that ecstasy polydrug users would perform worse than non-users on the behavioural measure and this would be supported by differences in cortical blood oxygenation. In the study, 20 ecstasy-polydrug users, 17 polydrug users and 19 drug-naive individuals took part. On day 1, drug use history was taken and questionnaire measures were completed. On day 2, participants completed a 20-min multitasking stressor while brain blood oxygenation was measured using functional near infrared spectroscopy (fNIRS). There were no significant differences between the three groups on the subscales of the multitasking stressor. In addition, there were no significant differences on self-report measures of perceived workload (NASA Task Load Index). In terms of mood, ecstasy users were significantly less calm and less relaxed compared with drug-naive controls. There were also significant differences at three voxels on the fNIRS, indicating decreased blood oxygenation in ecstasy users compared with drug-naive controls at voxel 2 (left dorsolateral prefrontal cortex), voxel 14 and voxel 16 (right dorsolateral prefrontal cortex), and compared with polydrug controls at V14. The results of the present study provide support for changes in brain activation during performance of demanding tasks in ecstasy polydrug users, which could be related to cerebral vasoconstriction.

  2. Palpatory method of measuring diastolic blood pressure

    Directory of Open Access Journals (Sweden)

    Dinesh Sahu

    2010-01-01

    Conclusion: The palpatory method would be very useful where frequent blood pressure measurement are being done manually like in wards, in busy OPD, patient on treadmill and also whenever stethoscope is not available. The blood pressure can be measured in noisy environment too.

  3. Blood transfusion improves renal oxygenation and renal function in sepsis-induced acute kidney injury in rats.

    Science.gov (United States)

    Zafrani, Lara; Ergin, Bulent; Kapucu, Aysegul; Ince, Can

    2016-12-20

    The effects of blood transfusion on renal microcirculation during sepsis are unknown. This study aimed to investigate the effect of blood transfusion on renal microvascular oxygenation and renal function during sepsis-induced acute kidney injury. Twenty-seven Wistar albino rats were randomized into four groups: a sham group (n = 6), a lipopolysaccharide (LPS) group (n = 7), a LPS group that received fluid resuscitation (n = 7), and a LPS group that received blood transfusion (n = 7). The mean arterial blood pressure, renal blood flow, and renal microvascular oxygenation within the kidney cortex were recorded. Acute kidney injury was assessed using the serum creatinine levels, metabolic cost, and histopathological lesions. Nitrosative stress (expression of endothelial (eNOS) and inducible nitric oxide synthase (iNOS)) within the kidney was assessed by immunohistochemistry. Hemoglobin levels, pH, serum lactate levels, and liver enzymes were measured. Fluid resuscitation and blood transfusion both significantly improved the mean arterial pressure and renal blood flow after LPS infusion. Renal microvascular oxygenation, serum creatinine levels, and tubular damage significantly improved in the LPS group that received blood transfusion compared to the group that received fluids. Moreover, the renal expression of eNOS was markedly suppressed under endotoxin challenge. Blood transfusion, but not fluid resuscitation, was able to restore the renal expression of eNOS. However, there were no significant differences in lactic acidosis or liver function between the two groups. Blood transfusion significantly improved renal function in endotoxemic rats. The specific beneficial effect of blood transfusion on the kidney could have been mediated in part by the improvements in renal microvascular oxygenation and sepsis-induced endothelial dysfunction via the restoration of eNOS expression within the kidney.

  4. Negative blood oxygen level dependent signals during speech comprehension.

    Science.gov (United States)

    Rodriguez Moreno, Diana; Schiff, Nicholas D; Hirsch, Joy

    2015-05-01

    Speech comprehension studies have generally focused on the isolation and function of regions with positive blood oxygen level dependent (BOLD) signals with respect to a resting baseline. Although regions with negative BOLD signals in comparison to a resting baseline have been reported in language-related tasks, their relationship to regions of positive signals is not fully appreciated. Based on the emerging notion that the negative signals may represent an active function in language tasks, the authors test the hypothesis that negative BOLD signals during receptive language are more associated with comprehension than content-free versions of the same stimuli. Regions associated with comprehension of speech were isolated by comparing responses to passive listening to natural speech to two incomprehensible versions of the same speech: one that was digitally time reversed and one that was muffled by removal of high frequencies. The signal polarity was determined by comparing the BOLD signal during each speech condition to the BOLD signal during a resting baseline. As expected, stimulation-induced positive signals relative to resting baseline were observed in the canonical language areas with varying signal amplitudes for each condition. Negative BOLD responses relative to resting baseline were observed primarily in frontoparietal regions and were specific to the natural speech condition. However, the BOLD signal remained indistinguishable from baseline for the unintelligible speech conditions. Variations in connectivity between brain regions with positive and negative signals were also specifically related to the comprehension of natural speech. These observations of anticorrelated signals related to speech comprehension are consistent with emerging models of cooperative roles represented by BOLD signals of opposite polarity.

  5. Neonatal oxidative stress depends on oxygen blood pressure in umbilical artery.

    Science.gov (United States)

    Proietti, F; De Bernardo, G; Longini, M; Sordino, D; Scaramuzzini, G; Tataranno, M L; Belvisi, E; Bazzini, F; Perrone, S; Buonocore, G

    2016-01-01

    With advancing gestation, partial pressure of oxygen (pO2) and pH fall significantly. Hypoxia is a main factor inducing free radical generation and thereby oxidative stress (OS). Placental and fetal tissue response when oxygen becomes restricted is complex and partially known. We tested the hypothesis that changes in umbilical artery and vein blood gas concentrations modulate OS occurrence in the newborn. Seventy umbilical artery and vein plasma samples were collected from healthy term newborns immediately after delivery. F2 Isoprostanes (F2-Isop) were measured in all samples as reliable markers of lipid peroxidation. Significantly lower pCO2 and higher pO2 and pH were found in umbilical vein than in artery, as expected. A positive correlation was detected between pH and pO2 only in umbilical artery (p=0.019). F2-Isop levels were no different between artery and vein in cord blood. Significant correlations were found between F2-Isop and pCO2 (p=0.025) as well as between F2-Isop and pH in umbilical vein (p=0.027). F2-Isop correlated with pCO2 (p=0.007) as well as with pO2 values (p=0.005) in umbilical artery blood. Oxidative stress (OS) in newborns depends on oxygen concentrations in umbilical artery. OS biomarkers significantly correlate with pO2 and in umbilical artery but not in umbilical vein. In normoxic conditions fetal-maternal gas exchanges occurring in placenta re-establish normal higher oxygen levels in umbilical vein than artery, with a normal production of free radicals without any deleterious effects.

  6. Aquatic respiration rate measurements at low oxygen concentrations.

    Directory of Open Access Journals (Sweden)

    Moritz Holtappels

    Full Text Available Despite its huge ecological importance, microbial oxygen respiration in pelagic waters is little studied, primarily due to methodological difficulties. Respiration measurements are challenging because of the required high resolution of oxygen concentration measurements. Recent improvements in oxygen sensing techniques bear great potential to overcome these limitations. Here we compare 3 different methods to measure oxygen consumption rates at low oxygen concentrations, utilizing amperometric Clark type sensors (STOX, optical sensors (optodes, and mass spectrometry in combination with (18-18O2 labeling. Oxygen concentrations and consumption rates agreed well between the different methods when applied in the same experimental setting. Oxygen consumption rates between 30 and 400 nmol L(-1 h(-1 were measured with high precision and relative standard errors of less than 3%. Rate detection limits in the range of 1 nmol L(-1 h(-1 were suitable for rate determinations in open ocean water and were lowest at the lowest applied O2 concentration.

  7. 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 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 ... +/- 12 vs. 262 +/- 39 ml/min). The present data demonstrate that muscle blood flow and oxygen delivery can be markedly reduced without affecting muscle oxygen uptake in the initial phase of moderate-intensity exercise, suggesting that blood flow does not limit muscle oxygen uptake at the onset...

  8. Some problems of treating acute arterial obstruction using hyperbaric oxygenation ultraviolet irradiation of blood and hemosorption

    International Nuclear Information System (INIS)

    Karyakin, A.M.

    1988-01-01

    Up-to-date state of the problem of acute arterial obstruction (AAO) is considered and clinical observations of patients with acute emboli and thrombosis of abdominal aorta and main arteries of lower extremitics are analyzed. Complex of detoxication therapy and measures on controlling AAO in patients during postoperation period is presented. Complex application of hemosorption, ultraviolet irradiation of autoblood and hyperbaric oxygenation enabled to achieve correction of some indices. Reliable evidences of high therapeutic efficiency of combined application of mentioned methods to patients with reconstructed blood flow are presented. 38 refs.; 3 tabs

  9. Regional cerebral blood flow and oxygen metabolism in normal pressure hydrocephalus after subarachnoid hemorrhage

    Energy Technology Data Exchange (ETDEWEB)

    Ishikawa, Masatsune; Kikuchi, Haruhiko; Taki, Waro; Kobayashi, Akira; Nishizawa, Sadahiko; Yonekura, Yoshiharu; Konishi, Junji [Kyoto Univ. (Japan). Faculty of Medicine

    1989-05-01

    To clarify the pathophysiology of normal pressure hydrocephalus (NPH) after subarachnoid hemorrhage, the authors measured cerebral blood flow (CBF), cerebral oxygen metabolic rates (CMRO{sub 2}), the cerebral oxygen extraction fraction (OEF), and cerebral blood volume (CBV) in eight normal volunteers, six SAH patients with NPH, and seven patients without NPH by {sup 15}O-labeled gas and positron emission tomography (PET). In the NPH group, PET revealed a decrease in CBF in the lower regions of the cerebral cortex and a diffuse decrease in CMRO{sub 2}. The decrease in CBF in the lower frontal, temporal, and occipital cortices was significantly greater in the NPH than in the non-NPH group. Reduction of CMRO{sub 2} was also more extensive in the NPH group, and both CBF and CMRO{sub 2} were more markedly decreased in the lower frontal region. OEF was increased in all areas in both of the patient groups, but the increase was not significant in most areas. CBF, CMRO{sub 2} and OEF did not significantly differ between the non-NPH group and the normal volunteers. There was no significant difference in CBV among the three groups. These results indicate that NPH involves impairment of cerebral oxygen metabolism in the lower regions of the cerebral cortex, particularly in the lower frontal region. (author).

  10. Impact of partial pressure of oxygen in blood samples on the performance of systems for self-monitoring of blood glucose.

    Science.gov (United States)

    Schmid, Christina; Baumstark, Annette; Pleus, Stefan; Haug, Cornelia; Tesar, Martina; Freckmann, Guido

    2014-03-01

    The partial pressure of oxygen (pO2) in blood samples can affect glucose measurements with oxygen-sensitive systems. In this study, we assessed the influence of different pO2 levels on blood glucose (BG) measurements with five glucose oxidase (GOD) systems and one glucose dehydrogenase (GDH) system. All selected GOD systems were indicated by the manufacturers to be sensitive to increased oxygen content of the blood sample. Venous blood samples of 16 subjects (eight women, eight men; mean age, 52 years; three with type 1 diabetes, four with type 2 diabetes, and nine without diabetes) were collected. Aliquots of each sample were adjusted to the following pO2 values: ≤45 mm Hg, approximately 70 mm Hg, and ≥150 mm Hg. For each system, five consecutive measurements on each sample were performed using the same test strip lot. Relative differences between the mean BG value at a pO2 level of approximately 70 mm Hg, which was considered to be similar to pO2 values in capillary blood samples, and the mean BG value at pO2 levels ≤45 mm Hg and ≥150 mm Hg were calculated. The GOD systems showed mean relative differences between 11.8% and 44.5% at pO2 values ≤45 mm Hg and between -14.6% and -21.2% at pO2 values ≥150 mm Hg. For the GDH system, the mean relative differences were -0.3% and -0.2% at pO2 values ≤45 mm Hg and ≥150 mm Hg, respectively. The magnitude of the pO2 impact on BG measurements seems to vary among the tested oxygen-sensitive GOD systems. The pO2 range in which oxygen-sensitive systems operate well should be provided in the product information.

  11. Oxygen respiration rates of benthic foraminifera as measured with oxygen microsensors

    DEFF Research Database (Denmark)

    Geslin, E.; Risgaard-Petersen, N.; Lombard, Fabien

    2011-01-01

    of the foraminiferal specimens. The results show a wide range of oxygen respiration rates for the different species (from 0.09 to 5.27 nl cell−1 h−1) and a clear correlation with foraminiferal biovolume showed by the power law relationship: R = 3.98 10−3 BioVol0.88 where the oxygen respiration rate (R) is expressed......Oxygen respiration rates of benthic foraminifera are still badly known, mainly because they are difficult to measure. Oxygen respiration rates of seventeen species of benthic foraminifera were measured using microelectrodes and calculated on the basis of the oxygen fluxes measured in the vicinity...... groups (nematodes, copepods, ostracods, ciliates and flagellates) suggests that benthic foraminifera have a lower oxygen respiration rates per unit biovolume. The total contribution of benthic foraminifera to the aerobic mineralisation of organic matter is estimated for the studied areas. The results...

  12. Relationships between human vitality and mitochondrial respiratory parameters, reactive oxygen species production and dNTP levels in peripheral blood mononuclear cells

    DEFF Research Database (Denmark)

    Maynard, Scott; Keijzers, Guido; Gram, Martin

    2013-01-01

    . Therefore, we measured a number of cellular parameters related to mitochondrial activity in peripheral blood mononuclear cells (PBMCs) isolated from middle-aged men, and tested for association with vitality. These parameters estimate mitochondrial respiration, reactive oxygen species (ROS) production...

  13. Investigating tissue respiration and skin microhaemocirculation under adaptive changes and the synchronization of blood flow and oxygen saturation rhythms

    International Nuclear Information System (INIS)

    Dunaev, A V; Palmer, S G; Stewart, N A; Sokolovski, S G; Rafailov, E U; Sidorov, V V; Krupatkin, A I; Rafailov, I E

    2014-01-01

    Multi-functional laser non-invasive diagnostic systems allow the study of a number of microcirculatory parameters, including index of blood microcirculation (I m ) (by laser Doppler flowmetry, LDF) and oxygen saturation (S t O 2 ) of skin tissue (by tissue reflectance oximetry, TRO). This research aimed to use such a system to investigate the synchronization of microvascular blood flow and oxygen saturation rhythms under normal and adaptive change conditions. Studies were conducted on eight healthy volunteers of 21–49 years. These volunteers were observed between one and six months, totalling 422 basic tests (3 min each). Measurements were performed on the palmar surface of the right middle finger and the lower forearm's medial surface. Rhythmic oscillations of LDF and TRO were studied using wavelet analysis. Combined tissue oxygen consumption data for all volunteers during ‘adaptive changes’ increased relative to normal conditions with and without arteriovenous anastomoses. Data analysis revealed resonance and synchronized rhythms in microvascular blood flow and oxygen saturation as an adaptive change in myogenic oscillation (vasomotion) resulting from exercise and possibly psychoemotional stress. Synchronization of myogenic rhythms during adaptive changes may lead to increased oxygen consumption as a result of increased microvascular blood flow velocity. (paper)

  14. Gas exchange efficiency of an oxygenator with integrated pulsatile displacement blood pump for neonatal patients.

    Science.gov (United States)

    Schlanstein, Peter C; Borchardt, Ralf; Mager, Ilona; Schmitz-Rode, Thomas; Steinseifer, Ulrich; Arens, Jutta

    2014-01-01

    Oxygenators have been used in neonatal extracorporeal membrane oxygenation (ECMO) since the 1970s. The need to develop a more effective oxygenator for this patient cohort exists due to their size and blood volume limitations. This study sought to validate the next design iteration of a novel oxygenator for neonatal ECMO with an integrated pulsatile displacement pump, thereby superseding an additional blood pump. Pulsating blood flow within the oxygenator is generated by synchronized active air flow expansion and contraction of integrated silicone pump tubes and hose pinching valves located at the oxygenator inlet and outlet. The current redesign improved upon previous prototypes by optimizing silicone pump tube distribution within the oxygenator fiber bundle; introduction of an oval shaped inner fiber bundle core, and housing; and a higher fiber packing density, all of which in combination reduced the priming volume by about 50% (50 to 27 mL and 41 to 20 mL, respectively). Gas exchange efficiency was tested for two new oxygenators manufactured with different fiber materials: one with coating and one with smaller pore size, both capable of long-term use (OXYPLUS® and CELGARD®). Results demonstrated that the oxygen transfer for both oxygenators was 5.3-24.7 mlO2/min for blood flow ranges of 100-500 mlblood/min. Carbon dioxide transfer for both oxygenators was 3.7-26.3 mlCO2/min for the same blood flow range. These preliminary results validated the oxygenator redesign by demonstrating an increase in packing density and thus in gas transfer, an increase in pumping capacity and a reduction in priming volume.

  15. Optoacoustic measurement of central venous oxygenation for assessment of circulatory shock: clinical study in cardiac surgery patients

    Science.gov (United States)

    Petrov, Irene Y.; Prough, Donald S.; Kinsky, Michael; Petrov, Yuriy; Petrov, Andrey; Henkel, S. Nan; Seeton, Roger; Salter, Michael G.; Esenaliev, Rinat O.

    2014-03-01

    Circulatory shock is a dangerous medical condition, in which blood flow cannot provide the necessary amount of oxygen to organs and tissues. Currently, its diagnosis and therapy decisions are based on hemodynamic parameters (heart rate, blood pressure, blood gases) and mental status of a patient, which all have low specificity. Measurement of mixed or central venous blood oxygenation via catheters is more reliable, but highly invasive and associated with complications. Our previous studies in healthy volunteers demonstrated that optoacoustic systems provide non-invasive measurement of blood oxygenation in specific vessels, including central veins. Here we report our first results of a clinical study in coronary artery bypass graft (CABG) surgery patients. We used a medical-grade OPO-based optoacoustic system developed in our laboratory to measure in real time blood oxygenation in the internal jugular vein (IJV) of these patients. A clinical ultrasound imaging system (GE Vivid e) was used for IJV localization. Catheters were placed in the IJV as part of routine care and blood samples taken via the catheters were processed with a CO-oximeter. The optoacoustic oxygenation data were compared to the CO-oximeter readings. Good correlation between the noninvasive and invasive measurements was obtained. The results of these studies suggest that the optoacoustic system can provide accurate, noninvasive measurements of central venous oxygenation that can be used for patients with circulatory shock.

  16. Red blood cell transfusions and tissue oxygenation in anemic hematology outpatients

    NARCIS (Netherlands)

    Yuruk, Koray; Bartels, Sebastiaan A.; Milstein, Dan M. J.; Bezemer, Rick; Biemond, Bart J.; Ince, Can

    2012-01-01

    BACKGROUND: There is little clinical evidence that red blood cell (RBC) transfusions improve oxygen availability at the microcirculatory level. We tested the hypotheses that anemia in chronically anemic patients with relatively healthy microcirculation would be associated with low tissue hemoglobin

  17. TRANSFUSION RESTORES BLOOD VISCOSITY AND REINSTATES MICROVASCULAR CONDITIONS FROM HEMORRHAGIC SHOCK INDEPENDENT OF OXYGEN CARRYING CAPACITY

    OpenAIRE

    Cabrales, Pedro; Intaglietta, Marcos; Tsai, Amy G.

    2007-01-01

    Systemic and microvascular hemodynamic responses to transfusion of oxygen using functional and non-functional packed fresh red blood cells (RBCs) from hemorrhagic shock were studied in the hamster window chamber model to determine the significance of RBCs on rheological and oxygen transport properties. Moderate hemorrhagic shock was induced by arterial controlled bleeding of 50% of the blood volume, and a hypovolemic state was maintained for one hour. Volume restitution was performed by infus...

  18. In situ measurements of oxygen dynamics in unsaturated archaeological deposits

    DEFF Research Database (Denmark)

    Matthiesen, Henning; Hollesen, Jørgen; Dunlop, Rory

    2015-01-01

    Oxygen is a key parameter in the degradation of archaeological material, but little is known of its dynamics in situ. In this study, 10 optical oxygen sensors placed in a 2 m deep test pit in the cultural deposits at Bryggen in Bergen have monitored oxygen concentrations every half hour for more ...... of the soil exceeds 10–15% vol, while oxygen dissolved in infiltrating rainwater is of less importance for the supply of oxygen in the unsaturated zone....... than a year. It is shown that there is a significant spatial and temporal variation in the oxygen concentration, which is correlated to measured soil characteristics, precipitation, soil water content and degradation of organic material. In these deposits oxygen typically occurs when the air content...

  19. Cerebral tissue oxygen saturation and extraction in preterm infants before and after blood transfusion

    NARCIS (Netherlands)

    van Hoften, Jacorina C. R.; Verhagen, Elise A.; Keating, Paul; ter Horst, Hendrik J.; Bos, Arend F.

    Objective Preterm infants often need red blood cell (RBC) transfusions. The aim of this study was to determine whether haemoglobin levels before transfusion were associated with regional cerebral tissue oxygen saturation (r(c)SO(2)) and fractional tissue oxygen extraction (FTOE) and whether RBC

  20. Association between intraoperative tissue oxygenation, arterial blood pressure and noradrenaline use in urological patients

    NARCIS (Netherlands)

    Spruit, R.J.; Schwarte, L.A.; Hakenberg, O.W.; Scheeren, T.

    2011-01-01

    Background and Goal of Study: Inadequate tissue oxygenation should be prevented during surgery as it might cause postoperative morbidity. In this observational study we looked at factors that might influence tissue oxygenation (StO2) such as blood pressure and use of vasoactive drugs. Materials and

  1. Relation of Mitochondrial Oxygen Consumption in Peripheral Blood Mononuclear Cells to Vascular Function in Type 2 Diabetes Mellitus

    Science.gov (United States)

    Hartman, Mor-Li; Shirihai, Orian S.; Holbrook, Monika; Xu, Guoquan; Kocherla, Marsha; Shah, Akash; Fetterman, Jessica L.; Kluge, Matthew A.; Frame, Alissa A.; Hamburg, Naomi M.; Vita, Joseph A.

    2014-01-01

    Recent studies have shown mitochondrial dysfunction and increased production of reactive oxygen species in peripheral blood mononuclear cells (PBMC’s) and endothelial cells from patients with diabetes mellitus. Mitochondria oxygen consumption is coupled to ATP production and also occurs in an uncoupled fashion during formation of reactive oxygen species by components of the electron transport chain and other enzymatic sites. We therefore hypothesized that diabetes would be associated with higher total and uncoupled oxygen consumption in PBMC’s that would correlate with endothelial dysfunction. We developed a method to measure oxygen consumption in freshly isolated PBMC’s and applied it to 26 patients with type 2 diabetes mellitus and 28 non-diabetic controls. Basal (192±47 vs. 161±44 pMoles/min, P=0.01), uncoupled (64±16 vs. 53±16 pMoles/min, P=0.007), and maximal (795±87 vs. 715±128 pMoles/min, P=0.01) oxygen consumption rates were higher in diabetic patients compared to controls. There were no significant correlations between oxygen consumption rates and endothelium-dependent flow-mediated dilation measured by vascular ultrasound. Non-endothelium-dependent nitroglycerin-mediated dilation was lower in diabetics (10.1±6.6 vs. 15.8±4.8%, P=0.03) and correlated with maximal oxygen consumption (R= −0.64, P=0.001). In summary, we found that diabetes mellitus is associated with a pattern of mitochondrial oxygen consumption consistent with higher production of reactive oxygen species. The correlation between oxygen consumption and nitroglycerin-mediated dilation may suggest a link between mitochondrial dysfunction and vascular smooth muscle cell dysfunction that merits further study. Finally, the described method may have utility for assessment of mitochondrial function in larger scale observational and interventional studies in humans. PMID:24558030

  2. Measurement of bone blood flow in sheep

    International Nuclear Information System (INIS)

    Rosenthal, M.S.; Lehner, C.E.; Pearson, D.W.; Kanikula, T.; Adler, G.; Venci, R.; Lanphier, E.H.; DeLuca, P.M. Jr.

    1984-01-01

    Bone blood flow in sheep tibia has been estimated via the measurement of the perfusion limited clearance of 41 Ar from the bone mineral matrix following fast neutron activation of 44 Ca. Tibia blood flows were estimated for the intact sheep, and after the installation of an intramedullary pressure tap to elevate bone marrow pressure by saline infusion. The results indicate that normal blood flow in the tibia is in the range of 1.1 to 3.7 ml/100ml-min in the intact animal and at normal marrow pressure. With an elevated intramedullary pressure of approximately 100 mmHg, the bone blood flow measured varied around 0.5 to 1.1 ml/100ml-min. 12 refs., 5 figs., 1 tab

  3. Simultaneous imaging of cerebral partial pressure of oxygen and blood flow during functional activation and cortical spreading depression

    Science.gov (United States)

    Sakadžić, Sava; Yuan, Shuai; Dilekoz, Ergin; Ruvinskaya, Svetlana; Vinogradov, Sergei A.; Ayata, Cenk; Boas, David A.

    2009-01-01

    We developed a novel imaging technique that provides real-time two-dimensional maps of the absolute partial pressure of oxygen and relative cerebral blood flow in rats by combining phosphorescence lifetime imaging with laser speckle contrast imaging. Direct measurement of blood oxygenation based on phosphorescence lifetime is not significantly affected by changes in the optical parameters of the tissue during the experiment. The potential of the system as a novel tool for quantitative analysis of the dynamic delivery of oxygen to support brain metabolism was demonstrated in rats by imaging cortical responses to forepaw stimulation and the propagation of cortical spreading depression waves. This new instrument will enable further study of neurovascular coupling in normal and diseased brain. PMID:19340106

  4. Effect of 2,3-diphosphoglycerate on oxygen affinity of blood in sickle cell anemia

    Science.gov (United States)

    Charache, Samuel; Grisolia, Santiago; Fiedler, Adam J.; Hellegers, Andre E.

    1970-01-01

    Blood of patients with sickle cell anemia (SS) exhibits decreased affinity for oxygen, although the oxygen affinity of hemoglobin S is the same as that of hemoglobin A. SS red cells contain more 2,3-diphosphoglycerate (DPG) than normal erythrocytes. The oxygen affinity of hemolyzed red cells is decreased by added DPG, and hemolysates prepared from SS red cells do not differ from normal hemolysates in this regard. Reduction of oxygen affinity to the levels found in intact SS red cells required DPG concentrations in excess of those found in most SS patients. The same was true of oxygen affinity of patients with pyruvate kinase deficiency. Other organic phosphates, as well as inorganic ions, are known to alter the oxygen affinity of dilute solutions of hemoglobin. These substances, the state of aggregation of hemoglobin molecules, and cytoarchitectural factors probably play roles in determining oxygen affinity of both normal and SS red cells. PMID:5443181

  5. Investigating Functional Extension of Optical Coherence Tomography for Spectroscopic Analysis of Blood Oxygen Saturation

    Science.gov (United States)

    Chen, Siyu

    Over the past two decades, optical coherence tomography (OCT) has been successfully applied to various fields of biomedical researching and clinical studies, including cardiology, urology, dermatology, dentistry, oncology, and most successfully, ophthalmology. This dissertation seeks to extend the current OCT practice, which is still largely morphology-based, into a new dimension, functional analysis of metabolic activities in vivo. More specifically, the investigation is focused on retrieving blood oxygen saturation (sO2) using intrinsic hemoglobin optical absorption contrast. Most mammalian cells rely on aerobic respiration to support cellular function, which means they consume oxygen to create adenosine triphosphate (ATP). Metabolic rate of oxygen (MRO2), a key hemodynamic parameter, characterizes how much oxygen is consumed during a given period of time, reflecting the metabolic activity of the target tissue. For example, retinal neurons are highly active and almost entirely rely on the moment-to-moment oxygen supply from retinal circulations. Thus, variation in MRO2 reveals the instantaneous activity of these neurons, shedding light on the physiological and pathophysiological change of cellular functions. Eventually, measuring MRO2 can potentially provide a biomarker for early-stage disease diagnosis, and serve as one benchmark for evaluating effectiveness of medical intervention during disease management. Essential in calculating MRO2, blood sO2 measurements using spectroscopic OCT analysis has been attempted as early as 2003. OCT is intrinsically sensitive to the blood optical absorption spectrum due to its wide-band illumination and detection scheme relying on back-scattered photon. However, accurate retrieval of blood sO2 using conventional near infrared (NIR) OCT systems in vivo has remained challenging. It was not until the development of OCT systems using visible light illumination (vis-OCT) when accurate measurement of blood sO2 was reported in live

  6. Determination of the PO2 temperature blood factor from oxygen dissociation curves.

    Science.gov (United States)

    Hérigault, R A; Soulard, C D; Teisseire, B P; Laurent, D N

    1983-01-01

    The variation with saturation of the temperature coefficient of PO2 in human blood (delta log PO2/delta T) was determined by continuous recording of the oxygen dissociation curve (ODC), at 37 degrees C and 25 degrees C, on the same blood samples. PCO2 and pH were held constant through an ODC run, and PCO2 was reduced at 25 degrees C to the value measured by anaerobic cooling of the same sample. delta log PO2/delta T was calculated from isosaturation points on the 37 and 25 degrees C curves. The temperature coefficient was also computed as an independent check on this method by determination of the effects of temperature (25, 30, 37 and 40 degrees C) on hemoglobin ligand interaction: fixed acid Bohr effect (delta log PO2/delta pH), carbamino-formation (delta log PO2/delta log PCO2) and hemoglobin oxygen affinity. The values of delta log PO2/delta T ratio obtained from the two different approaches were found to be in good agreement. The coefficient decreased when [H+] concentration was increased. A linear relationship between the Bohr factor and the temperature was found: delta log PO2/delta pH = 0.00267 T-0.520 (r = 0.85; n = 40) At 25 degrees C, the carbamino-formation was one order of magnitude lower than at 37 degrees C. Acid-base state and saturation value appeared to be major determinant factors for the temperature correction coefficient to be applied to blood PO2 values measured at standard (37 degrees C) temperature.

  7. Evaluation of Nd:YAG laser on partial oxygen saturation of pulpal blood in anterior hypersensitive teeth.

    Science.gov (United States)

    Birang, Reza; Kaviani, Naser; Mohammadpour, Mehdi; Abed, Ahmad Moghareh; Gutknecht, Norbert; Mir, Maziar

    2008-07-01

    Dentine hypersensitivity has of long been known to be a common clinical problem in dental practices. Lasers have recently come to play a prominent role in the treatment of this disorder. They might, however, cause dental pulp damage. This study was conducted to evaluate the effect of Nd:yttrium-aluminum-garnet (YAG) laser on partial oxygen saturation of pulpal blood in sensitive anterior teeth. In this clinical trial, 65 hypersensitive teeth were selected and randomly allocated to two groups. The study group involved Nd:YAG laser treatment, while no treatment was employed for the control group. Using a pulse oximetry system, evaluations were preformed of the partial oxygen saturation in the pulpal blood before, immediately after, 1 week after, and 1 month after the treatment. The results were analyzed using the SPSS software and repeated-measures analysis of variance and paired-samples t tests. The mean partial oxygen saturation of the blood was found to be 85.4% in the study group, which was not significantly different from that of the control group. No significant differences were observed in the control group between the means obtained from pretreatment and post-treatment intervals (P > 0.05). The Post-treatment partial oxygen saturation mean rose to 89.3% (P = 0.001) and remained constant throughout the following week after it. However, no significant differences were found between the pretreatment partial oxygen saturation mean and the same measurement 1 month after treatment (P = 0.702). Nd:YAG laser therapy for dentine desensitization of anterior teeth caused no persistent changes in the partial oxygen saturation of pulpal blood. It may, therefore, be concluded that the diffusion of heat induced by the Nd:YAG laser into the pulp within the limit of the desensitization parameters cause no irreversible damages in the dental pulp.

  8. Alveolar gas exchange and tissue oxygenation during incremental treadmill exercise, and their associations with blood O2 carrying capacity

    Directory of Open Access Journals (Sweden)

    Antti-Pekka E. Rissanen

    2012-07-01

    Full Text Available The magnitude and timing of oxygenation responses in highly active leg muscle, less active arm muscle, and cerebral tissue, have not been studied with simultaneous alveolar gas exchange measurement during incremental treadmill exercise. Nor is it known, if blood O2 carrying capacity affects the tissue-specific oxygenation responses. Thus, we investigated alveolar gas exchange and tissue (m. vastus lateralis, m. biceps brachii, cerebral cortex oxygenation during incremental treadmill exercise until volitional fatigue, and their associations with blood O2 carrying capacity in 22 healthy men. Alveolar gas exchange was measured, and near-infrared spectroscopy (NIRS was used to monitor relative concentration changes in oxy- (Δ[O2Hb], deoxy- (Δ[HHb] and total hemoglobin (Δ[tHb], and tissue saturation index (TSI. NIRS inflection points (NIP, reflecting changes in tissue-specific oxygenation, were determined and their coincidence with ventilatory thresholds (anaerobic threshold (AT, respiratory compensation point (RC; V-slope method was examined. Blood O2 carrying capacity (total hemoglobin mass (tHb-mass was determined with the CO-rebreathing method. In all tissues, NIPs coincided with AT, whereas RC was followed by NIPs. High tHb-mass associated with leg muscle deoxygenation at peak exercise (e.g., Δ[HHb] from baseline walking to peak exercise vs. tHb-mass: r = 0.64, p < 0.01, but not with arm muscle- or cerebral deoxygenation. In conclusion, regional tissue oxygenation was characterized by inflection points, and tissue oxygenation in relation to alveolar gas exchange during incremental treadmill exercise resembled previous findings made during incremental cycling. It was also found out, that O2 delivery to less active m. biceps brachii may be limited by an accelerated increase in ventilation at high running intensities. In addition, high capacity for blood O2 carrying was associated with a high level of m. vastus lateralis deoxygenation at peak

  9. Global brain blood-oxygen level responses to autonomic challenges in obstructive sleep apnea.

    Directory of Open Access Journals (Sweden)

    Paul M Macey

    Full Text Available Obstructive sleep apnea (OSA is accompanied by brain injury, perhaps resulting from apnea-related hypoxia or periods of impaired cerebral perfusion. Perfusion changes can be determined indirectly by evaluation of cerebral blood volume and oxygenation alterations, which can be measured rapidly and non-invasively with the global blood oxygen level dependent (BOLD signal, a magnetic resonance imaging procedure. We assessed acute BOLD responses in OSA subjects to pressor challenges that elicit cerebral blood flow changes, using a two-group comparative design with healthy subjects as a reference. We separately assessed female and male patterns, since OSA characteristics and brain injury differ between sexes. We studied 94 subjects, 37 with newly-diagnosed, untreated OSA (6 female (age mean ± std: 52.1±8.1 yrs; apnea/hypopnea index [AHI]: 27.7±15.6 events/hr and 31 male 54.3±8.4 yrs; AHI: 37.4±19.6 events/hr, and 20 female (age 50.5±8.1 yrs and 37 male (age 45.6±9.2 yrs healthy control subjects. We measured brain BOLD responses every 2 s while subjects underwent cold pressor, hand grip, and Valsalva maneuver challenges. The global BOLD signal rapidly changed after the first 2 s of each challenge, and differed in magnitude between groups to two challenges (cold pressor, hand grip, but not to the Valsalva maneuver (repeated measures ANOVA, p<0.05. OSA females showed greater differences from males in response magnitude and pattern, relative to healthy counterparts. Cold pressor BOLD signal increases (mean ± adjusted standard error at the 8 s peak were: OSA 0.14±0.08% vs. Control 0.31±0.06%, and hand grip at 6 s were: OSA 0.08±0.03% vs. Control at 0.30±0.02%. These findings, indicative of reduced cerebral blood flow changes to autonomic challenges in OSA, complement earlier reports of altered resting blood flow and reduced cerebral artery responsiveness. Females are more affected than males, an outcome which may contribute to the sex

  10. Cerebral oxygen metabolism and cerebral blood flow in man during light sleep (stage 2)

    DEFF Research Database (Denmark)

    Madsen, P L; Schmidt, J F; Holm, S

    1991-01-01

    We measured cerebral blood flow (CBF) and cerebral metabolic rate of oxygen (CMRO2) during light sleep (stage 2) in 8 young healthy volunteers using the Kety-Schmidt technique with 133Xe as the inert gas. Measurements were performed during wakefulness and light sleep as verified by standard...... polysomnography. Unlike our previous study in man showing a highly significant 25% decrease in CMRO2 during deep sleep (stage 3-4) we found a modest but statistically significant decrease of 5% in CMRO2 during stage 2 sleep. Deep and light sleep are both characterized by an almost complete lack of mental activity....... They differ in respect of arousal threshold as a stronger stimulus is required to awaken a subject from deep sleep as compared to light sleep. Our results suggest that during non-rapid eye movement sleep cerebral metabolism and thereby cerebral synaptic activity is correlated to cerebral readiness rather than...

  11. Red blood cell transfusions and tissue oxygenation in anemic hematology outpatients.

    Science.gov (United States)

    Yuruk, Koray; Bartels, Sebastiaan A; Milstein, Dan M J; Bezemer, Rick; Biemond, Bart J; Ince, Can

    2012-03-01

    There is little clinical evidence that red blood cell (RBC) transfusions improve oxygen availability at the microcirculatory level. We tested the hypotheses that anemia in chronically anemic patients with relatively healthy microcirculation would be associated with low tissue hemoglobin (Hb) and tissue oxygenation levels and that these conditions would be improved after RBC transfusions. Near-infrared spectroscopy (NIRS) was used to determine tissue oxygen saturation (StO(2)) and tissue Hb index (THI; an index of the amount of Hb in the NIRS measurement volume) in the thenar eminence and sublingual tissue before and 30 minutes after RBC transfusions in 20 chronically anemic hematology outpatients. Data are presented as median (25%-75%). The patients received three (two to three) bags of RBCs in saline-adenine-glucose-mannitol with an age of 21 (7-21) days, which was infused intravenously at the rate of 0.7 bag/hr. RBC transfusions significantly increased hematocrit level from 26% (24%-28%) to 32% (30%-34%; p viscosity from 3.4 (3.1-3.5) mPa/sec to 4.2 (4.0-4.5) mPa/sec (p < 0.0001), thenar StO(2) from 81% (80%-84%) to 86% (81%-89%; p = 0.002), thenar THI from 11.2 (9.3-13.3) AU to 13.7 (9.7-15.3) AU (p = 0.024), sublingual StO(2) from 86% (81%-89%) to 91% (86%-92%; p < 0.0001), and sublingual THI from 15.2 (13.0-17.4) AU to 17.2 (13.5-19.7) AU (p = 0.040). Although anemia in chronically anemic hematology outpatients was not associated with low StO(2) and THI levels, RBC transfusions were successful in improving these variables. © 2011 American Association of Blood Banks.

  12. Hepatic encephalopathy is associated with decreased cerebral oxygen metabolism and blood flow, not increased ammonia uptake

    DEFF Research Database (Denmark)

    Dam, Gitte; Keiding, Susanne; Munk, Ole Lajord

    2013-01-01

    Studies have shown decreased cerebral oxygen metabolism (CMRO(2)) and blood flow (CBF) in patients with cirrhosis with hepatic encephalopathy (HE). It remains unclear, however, whether these disturbances are associated with HE or with cirrhosis itself and how they may relate to arterial blood...... associated with HE rather than the liver disease as such. The changes in CMRO(2) and CBF could not be linked to blood ammonia concentration or CMRA....

  13. HERSCHEL MEASUREMENTS OF MOLECULAR OXYGEN IN ORION

    International Nuclear Information System (INIS)

    Goldsmith, Paul F.; Chen, Jo-Hsin; Li Di; Liseau, Rene; Black, John H.; Bell, Tom A.; Hollenbach, David; Kaufman, Michael J.; Lis, Dariusz C.; Melnick, Gary; Neufeld, David; Pagani, Laurent; Encrenaz, Pierre; Snell, Ronald; Benz, Arnold O.; Bruderer, Simon; Bergin, Edwin; Caselli, Paola; Caux, Emmanuel; Falgarone, Edith

    2011-01-01

    We report observations of three rotational transitions of molecular oxygen (O 2 ) in emission from the H 2 Peak 1 position of vibrationally excited molecular hydrogen in Orion. We observed the 487 GHz, 774 GHz, and 1121 GHz lines using the Heterodyne Instrument for the Far Infrared on the Herschel Space Observatory, having velocities of 11 km s -1 to 12 km s -1 and widths of 3 km s -1 . The beam-averaged column density is N(O 2 ) = 6.5 x 10 16 cm -2 , and assuming that the source has an equal beam-filling factor for all transitions (beam widths 44, 28, and 19''), the relative line intensities imply a kinetic temperature between 65 K and 120 K. The fractional abundance of O 2 relative to H 2 is (0.3-7.3) x 10 -6 . The unusual velocity suggests an association with a ∼5'' diameter source, denoted Peak A, the Western Clump, or MF4. The mass of this source is ∼10 M sun and the dust temperature is ≥150 K. Our preferred explanation of the enhanced O 2 abundance is that dust grains in this region are sufficiently warm (T ≥ 100 K) to desorb water ice and thus keep a significant fraction of elemental oxygen in the gas phase, with a significant fraction as O 2 . For this small source, the line ratios require a temperature ≥180 K. The inferred O 2 column density ≅5 x 10 18 cm -2 can be produced in Peak A, having N(H 2 ) ≅ 4 x 10 24 cm -2 . An alternative mechanism is a low-velocity (10-15 km s -1 ) C-shock, which can produce N(O 2 ) up to 10 17 cm -2 .

  14. Oxygen radical-scavenging capacities of peptides from swine blood

    African Journals Online (AJOL)

    USER

    2010-08-02

    Aug 2, 2010 ... ... a basic factor in maintaining life and health (Stadtman and Levine, 2003). ... these problems, peptides from swine blood (PSB) was obtained by the ... (0.05 µm ceramic membrane), ultra-filtration (1000 Da), and spray-drying.

  15. Discrepancies between measured changes of radiobiological hypoxic fraction and oxygen tension monitoring using two assay systems

    International Nuclear Information System (INIS)

    Sasai, K.; Brown, J.M.

    1994-01-01

    This study was conducted to assess the ability of computerized pO 2 histography to measure changes in tumor oxygenation produced by low oxygen breathing. Female syngeneic C3H/Km mice bearing SCC VII/St carcinomas were used in these experiments. Changes in tumor oxygenation produced by the mice breathing 10% oxygen were assessed with computerized pO2 histography, 3 H-misonidazole binding, and the paired survival curve assay of radiosensitivity. The hypoxic cell fraction of the tumors in mice breathing 10% oxygen was 3.1 times higher than that of tumors in mice breathing normal air determined by an in vivo-in vitro clonogenic assay. Binding of radiolabeled misonidazole to the tumors in mice breathing 10% oxygen was also significantly higher than that to tumors in mice breathing normal air (p 2 value for the tumor. The number of pO 2 readings lower than 5 mmHg in the tumor was not affected by the 10% oxygen breathing. These findings indicate that increases in radiobiological hypoxic fraction produced by lower blood oxygen levels may not correlate well with the results of polarographic measurements of tumor pO 2 levels. 29 refs., 4 figs., 1 tab

  16. Ion measurements in premixed methane-oxygen flames

    KAUST Repository

    Alquaity, Awad; Hourani, Nadim; Chahine, May; Selim, Hatem; Sarathy, Mani; Farooq, Aamir

    2014-01-01

    Mass Spectrometer (MBMS) is utilized to measure ion concentration profiles in premixed methane-oxygen-argon burner-stabilized flames. Lean, stoichiometric and rich flames at atmospheric pressure are used to study the dependence of ion chemistry

  17. Multi-modal in vivo imaging of brain blood oxygenation, blood flow and neural calcium dynamics during acute seizures

    Science.gov (United States)

    Ringuette, Dene; Jeffrey, Melanie A.; Carlen, Peter L.; Levi, Ofer

    2016-03-01

    Dysfunction of the vascular endothelium has been implicated in the development of epilepsy. To better understand the relation between vascular function and seizure and provide a foundation for interpreting results from functional imaging in chronic disease models, we investigate the relationship between intracellular calcium dynamics and local cerebral blood flow and blood oxygen saturation during acute seizure-like events and pharmacological seizure rescue. To probe the relation between the aforementioned physiological markers in an acute model of epilepsy in rats, we integrated three different optical modalities together with electrophysiological recordings: Laser speckle contrast imaging (LSCI) was used to study changes in flow speeds, Intrinsic optical signal imaging (IOSI) was used to monitor changes in oxygenated, de-oxygenated, and total hemoglobin concentration, and Calcium-sensitive dye imaging was used to monitor intracellular calcium dynamics. We designed a dedicated cortical flow chamber to remove superficial blood and dye resulting from the injection procedure, which reduced spurious artifacts. The near infrared light used for IOSI and LSCI was delivered via a light pipe integrated with the flow chamber to minimize the effect of fluid surface movement on illumination stability. Calcium-sensitive dye was injected via a glass electrode used for recording the local field potential. Our system allowed us to observe and correlate increases in intracellular calcium, blood flow and blood volume during seizure-like events and provide a quantitative analysis of neurovascular coupling changes associated with seizure rescue via injection of an anti-convulsive agent.

  18. Prefrontal oxygenation correlates to the responses in facial skin blood flows during exposure to pleasantly charged movie.

    Science.gov (United States)

    Matsukawa, Kanji; Endo, Kana; Asahara, Ryota; Yoshikawa, Miho; Kusunoki, Shinya; Ishida, Tomoko

    2017-11-01

    Our laboratory reported that facial skin blood flow may serve as a sensitive tool to assess an emotional status. Cerebral neural correlates during emotional interventions should be sought in relation to the changes in facial skin blood flow. To test the hypothesis that prefrontal activity has positive relation to the changes in facial skin blood flow during emotionally charged stimulation, we examined the dynamic changes in prefrontal oxygenation (with near-infrared spectroscopy) and facial skin blood flows (with two-dimensional laser speckle and Doppler flowmetry) during emotionally charged audiovisual challenges for 2 min (by viewing comedy, landscape, and horror movie) in 14 subjects. Hand skin blood flow and systemic hemodynamics were simultaneously measured. The extents of pleasantness and consciousness for each emotional stimulus were estimated by subjective rating from -5 (the most unpleasant; the most unconscious) to +5 (the most pleasant; the most conscious). Positively charged emotional stimulation (comedy) simultaneously decreased ( P  horror) or neutral (landscape) emotional stimulation did not alter or slightly decreased them. Any of hand skin blood flow and systemic cardiovascular variables did not change significantly during positively charged emotional stimulation. The changes in prefrontal oxygenation had a highly positive correlation with the changes in facial skin blood flow without altering perfusion pressure, and they were inversely correlated with the subjective rating of pleasantness. The reduction in prefrontal oxygenation during positively charged emotional stimulation suggests a decrease in prefrontal neural activity, which may in turn elicit neurally mediated vasoconstriction of facial skin blood vessels. © 2017 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.

  19. Cerebral blood flow and oxygen consumption during ethanol withdrawal in the rat.

    Science.gov (United States)

    Hemmingsen, R; Barry, D I; Hertz, M M; Klinken, L

    1979-09-14

    The ethanol withdrawal syndrome in man and animals is characterized by signs of CNS hyperactivity although a direct measurement of a physiological variable reflecting this CNS hyperactivity has never been performed in untreated man or in animals. We induced ethanol dependence in the rat by means of intragastric intubation with a 20% w/v ethanol solution, thus keeping the animals in a state of continuous severe intoxication for 3--4 days; during the subsequent state of withdrawal characterized by tremor, rigidity, stereotyped movements and general seizures a 25% increase in cerebral oxygen consumption (CMRO2) could be measured; this increase was not due to catecholamines originating from adrenal medulla as adrenomedullectomized animals showed a similar increase in CMRO2 (28%); the withdrawing animals showed a corresponding cerebral blood flow (CBF) increase. The elevated CMRO2 and CBF could be reduced to normal by administration of a beta-adrenergic receptor blocker (propranolol 2 mg/kg i.v.), and hence the increased CMRO2 during ethanol withdrawal could be related to catecholaminergic systems in the brain, e.g. the noradrenergic locus coeruleus system which is anatomically well suited as a general activating system. This interpretation is supported by the earlier neurochemical finding of an increased cerebral noradrenaline turnover during ethanol withdrawal. The exact mechanism underlying the increased cerebral oxygen consumption during ethanol withdrawal and the effect of propranolol on cerebral function during this condition remains to be clarified.

  20. Image-Based Modeling of Blood Flow and Oxygen Transfer in Feto-Placental Capillaries.

    Directory of Open Access Journals (Sweden)

    Philip Pearce

    Full Text Available During pregnancy, oxygen diffuses from maternal to fetal blood through villous trees in the placenta. In this paper, we simulate blood flow and oxygen transfer in feto-placental capillaries by converting three-dimensional representations of villous and capillary surfaces, reconstructed from confocal laser scanning microscopy, to finite-element meshes, and calculating values of vascular flow resistance and total oxygen transfer. The relationship between the total oxygen transfer rate and the pressure drop through the capillary is shown to be captured across a wide range of pressure drops by physical scaling laws and an upper bound on the oxygen transfer rate. A regression equation is introduced that can be used to estimate the oxygen transfer in a capillary using the vascular resistance. Two techniques for quantifying the effects of statistical variability, experimental uncertainty and pathological placental structure on the calculated properties are then introduced. First, scaling arguments are used to quantify the sensitivity of the model to uncertainties in the geometry and the parameters. Second, the effects of localized dilations in fetal capillaries are investigated using an idealized axisymmetric model, to quantify the possible effect of pathological placental structure on oxygen transfer. The model predicts how, for a fixed pressure drop through a capillary, oxygen transfer is maximized by an optimal width of the dilation. The results could explain the prevalence of fetal hypoxia in cases of delayed villous maturation, a pathology characterized by a lack of the vasculo-syncytial membranes often seen in conjunction with localized capillary dilations.

  1. Calculating acid-base and oxygenation status during COPD exacerbation using mathematically arterialised venous blood

    DEFF Research Database (Denmark)

    Rees, Stephen Edward; Rychwicka-Kielek, Beate A; Andersen, Bjarne F

    2012-01-01

    Abstract Background: Repeated arterial puncture is painful. A mathematical method exists for transforming peripheral venous pH, PCO2 and PO2 to arterial eliminating the need for arterial sampling. This study evaluates this method to monitor acid-base and oxygenation during admission...... for exacerbation of chronic obstructive pulmonary disease (COPD). Methods: Simultaneous arterial and peripheral venous blood was analysed. Venous values were used to calculate arterial pH, PCO2 and PO2, with these compared to measured values using Bland-Altman analysis and scatter plots. Calculated values of PO2......H, PCO2 and PO2 were 7.432±0.047, 6.8±1.7 kPa and 9.2±1.5 kPa, respectively. Calculated and measured arterial pH and PCO2 agreed well, differences having small bias and SD (0.000±0.022 pH, -0.06±0.50 kPa PCO2), significantly better than venous blood alone. Calculated PO2 obeyed the clinical rules...

  2. Blood pressure and calf muscle oxygen extraction during plantar flexion exercise in peripheral artery disease.

    Science.gov (United States)

    Luck, J Carter; Miller, Amanda J; Aziz, Faisal; Radtka, John F; Proctor, David N; Leuenberger, Urs A; Sinoway, Lawrence I; Muller, Matthew D

    2017-07-01

    Peripheral artery disease (PAD) is an atherosclerotic vascular disease that affects 200 million people worldwide. Although PAD primarily affects large arteries, it is also associated with microvascular dysfunction, an exaggerated blood pressure (BP) response to exercise, and high cardiovascular mortality. We hypothesized that fatiguing plantar flexion exercise that evokes claudication elicits a greater reduction in skeletal muscle oxygenation (SmO 2 ) and a higher rise in BP in PAD compared with age-matched healthy subjects, but low-intensity steady-state plantar flexion elicits similar responses between groups. In the first experiment, eight patients with PAD and eight healthy controls performed fatiguing plantar flexion exercise (from 0.5 to 7 kg for up to 14 min). In the second experiment, seven patients with PAD and seven healthy controls performed low-intensity plantar flexion exercise (2.0 kg for 14 min). BP, heart rate (HR), and SmO 2 were measured continuously using near-infrared spectroscopy (NIRS). SmO 2 is the ratio of oxygenated hemoglobin to total hemoglobin, expressed as a percent. At fatigue, patients with PAD had a greater increase in mean arterial BP (18 ± 2 vs. vs. 10 ± 2 mmHg, P = 0.029) and HR (14 ± 2 vs. 6 ± 2 beats/min, P = 0.033) and a greater reduction in SmO 2 (-54 ± 10 vs. -12 ± 4%, P = 0.001). However, both groups had similar physiological responses to low-intensity, nonpainful plantar flexion exercise. These data suggest that patients with PAD have altered oxygen uptake and/or utilization during fatiguing exercise coincident with an augmented BP response. NEW & NOTEWORTHY In this laboratory study, patients with peripheral artery disease performed plantar flexion exercise in the supine posture until symptoms of claudication occurred. Relative to age- and sex-matched healthy subjects we found that patients had a higher blood pressure response, a higher heart rate response, and a greater reduction in skeletal muscle oxygenation as

  3. Regional cerebral blood flow and oxygen consumption during normal human sleep

    Energy Technology Data Exchange (ETDEWEB)

    Takahashi, Ken [Toho Univ., Tokyo (Japan). School of Medicine

    1989-09-01

    Regional cerebral blood flow (rCBF), regional oxygen extraction fraction (rCEF) and regional cerebral metabolic rate for oxygen (rCMRO{sub 2}) were measured using the continuous inhalation technique for {sup 15}O with positron emission tomography (PET) during both wakefulness and sleep. Ten paid volunteers, with a mean age of 21.6 yrs., were deprived of sleep for a period of approximately 20 hours, and the experiments were performed mostly in the morning. {sup 15}O activity of both whole blood and the plasma, pixel count of PET, total arterial blood oxygen content were used for analysis of rCBF, rOEF and rCMRO{sub 2}. PET scannings were carried out mostly during the very light non-rapid eye movement (NREM) sleep, i.e. stage 1 and/or 2, and wakefulness. About 10 minutes after the start of continuous inhalation of {sup 15}O gas, the {sup 15}O activity of the brain was found to be in a steady-state condition. During this steady-state condition, PET scannings were performed for about 10 minutes. Regions of interest, square in shape and having an area of 2.8 cm{sup 3}, were set in each cortex on PET images of a horizontal cross-section of the brain, set at 45 mm above the orbitomeatal line. The rCBF and rCMRO{sub 2} were analysed in 5 of 10 male subjects during both wakefulness and NREM sleep, and only 3 were done during three sleep stages, including REM sleep. Levels of rCBF and rCMRO{sub 2} were found to be decreased in NREM sleep, and the decreasing rates were calculated at 10.2% and 7.6% from the level of wakefulness, respectively. There was no significant difference in the mean value of rOEF between wakefulness and NREM sleep. There were no significant regional differences found in the rate of decrease among the frontal, temporal and occipital cortices. It was considered that the decrease of rCBF and rCMRO{sub 2} during NREM sleep suggested a decrease of the activity levels in the cerebral functions. (author).

  4. Regional cerebral blood flow and oxygen consumption during normal human sleep

    International Nuclear Information System (INIS)

    Takahashi, Ken

    1989-01-01

    Regional cerebral blood flow (rCBF), regional oxygen extraction fraction (rCEF) and regional cerebral metabolic rate for oxygen (rCMRO 2 ) were measured using the continuous inhalation technique for 15 O with positron emission tomography (PET) during both wakefulness and sleep. Ten paid volunteers, with a mean age of 21.6 yrs., were deprived of sleep for a period of approximately 20 hours, and the experiments were performed mostly in the morning. 15 O activity of both whole blood and the plasma, pixel count of PET, total arterial blood oxygen content were used for analysis of rCBF, rOEF and rCMRO 2 . PET scannings were carried out mostly during the very light non-rapid eye movement (NREM) sleep, i.e. stage 1 and/or 2, and wakefulness. About 10 minutes after the start of continuous inhalation of 15 O gas, the 15 O activity of the brain was found to be in a steady-state condition. During this steady-state condition, PET scannings were performed for about 10 minutes. Regions of interest, square in shape and having an area of 2.8 cm 3 , were set in each cortex on PET images of a horizontal cross-section of the brain, set at 45 mm above the orbitomeatal line. The rCBF and rCMRO 2 were analysed in 5 of 10 male subjects during both wakefulness and NREM sleep, and only 3 were done during three sleep stages, including REM sleep. Levels of rCBF and rCMRO 2 were found to be decreased in NREM sleep, and the decreasing rates were calculated at 10.2% and 7.6% from the level of wakefulness, respectively. There was no significant difference in the mean value of rOEF between wakefulness and NREM sleep. There were no significant regional differences found in the rate of decrease among the frontal, temporal and occipital cortices. It was considered that the decrease of rCBF and rCMRO 2 during NREM sleep suggested a decrease of the activity levels in the cerebral functions. (author)

  5. 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

  6. Oxygen-implanted induced formation of oxide layer enhances blood compatibility on titanium for biomedical applications

    Energy Technology Data Exchange (ETDEWEB)

    Hung, Wei-Chiang [School of Oral Hygiene, Taipei Medical University, Taipei 110, Taiwan (China); Department of Dentistry, Taipei Medical University Hospital, Taipei 110, Taiwan (China); Chang, Fang-Mo [School of Dentistry, Taipei Medical University, Taipei 110, Taiwan (China); Yang, Tzu-Sen [Master Program in Graduate Institute of Nanomedicine and Medical Engineering, Taipei Medical University, Taipei 110, Taiwan (China); Ou, Keng-Liang [School of Dentistry, Taipei Medical University, Taipei 110, Taiwan (China); Research Center for Biomedical Implants and Microsurgery Devices, Taipei Medical University, Taipei 110, Taiwan (China); Department of Dentistry, Taipei Medical University-Shuang-Ho Hospital, Taipei 235, Taiwan (China); Lin, Che-Tong [School of Dentistry, Taipei Medical University, Taipei 110, Taiwan (China); Peng, Pei-Wen, E-mail: apon@tmu.edu.tw [School of Dental Technology, Taipei Medical University, Taipei 110, Taiwan (China)

    2016-11-01

    Titanium dioxide (TiO{sub 2}) layers were prepared on a Ti substrate by using oxygen plasma immersion ion implantation (oxygen PIII). The surface chemical states, structure, and morphology of the layers were studied using X-ray photoelectron spectroscopy, X-ray diffraction, Raman microscopy, atomic force microscopy and scanning electron microscope. The mechanical properties, such as the Young's modulus and hardness, of the layers were investigated using nanoindentation testing. The Ti{sup 4+} chemical state was determined to be present on oxygen-PIII-treated surfaces, which consisted of nanocrystalline TiO{sub 2} with a rutile structure. Compared with Ti substrates, the oxygen-PIII-treated surfaces exhibited decreased Young's moduli and hardness. Parameters indicating the blood compatibility of the oxygen-PIII-treated surfaces, including the clotting time and platelet adhesion and activation, were studied in vitro. Clotting time assays indicated that the clotting time of oxygen-PIII-treated surfaces was longer than that of the Ti substrate, which was associated with decreased fibrinogen adsorption. In conclusion, the surface characteristics and the blood compatibility of Ti implants can be modified and improved using oxygen PIII. - Highlights: • The Ti{sup 4+} chemical state was determined to be present on oxygen-PIII-treated surfaces. • The nanocrystalline TiO{sub 2} with a rutile structure was formed on titanium surfaces. • A nanoporous TiO{sub 2} layer in the rutile phase prepared using oxygen PIII treatment can be used to prolong blood clot formation.

  7. Monitoring and measurement of oxygen concentrations in liquid sodium

    International Nuclear Information System (INIS)

    Smith, D.L.

    1976-01-01

    The measurement of oxygen concentrations in sodium at levels of interest for LMFBR applications is reviewed. Additional data are presented to support the validity of the vanadium-equilibration method as a reference for determination of oxygen concentrations in sodium at levels equal to or less than 15 ppM. Operating experience with electrochemical oxygen meters that have a thoria-yttria electrolyte and a Na--Na 2 O reference electrode is described. Meter lifetimes in excess of one year have generally been achieved for operating temperatures of 352 and 402 0 C, and fairly stable emfs have been observed for periods of several months. 7 fig, 21 references

  8. Performance evaluation of photoacoustic oximetry imaging systems using a dynamic blood flow phantom with tunable oxygen saturation

    Science.gov (United States)

    Vogt, William C.; Zhou, Xuewen; Andriani, Rudy; Wear, Keith A.; Garra, Brian S.; Pfefer, Joshua

    2018-02-01

    Photoacoustic Imaging (PAI) is an emerging technology with strong potential for broad clinical applications from breast cancer detection to cerebral monitoring due to its ability to compute maps of blood oxygen saturation (SO2) distribution in deep tissues using multispectral imaging. However, no well-validated consensus test methods currently exist for evaluating oximetry-specific performance characteristics of PAI devices. We have developed a phantombased flow system capable of rapid SO2 adjustment to serve as a test bed for elucidation of factors impacting SO2 measurement and quantitative characterization of device performance. The flow system is comprised of a peristaltic pump, membrane oxygenator, oxygen and nitrogen gas, and in-line oxygen, pH, and temperature sensors that enable real-time estimation of SO2 reference values. Bovine blood was delivered through breast-relevant tissue phantoms containing vessel-mimicking fluid channels, which were imaged using a custom multispectral PAI system. Blood was periodically drawn for SO2 measurement in a clinical-grade CO-oximeter. We used this flow phantom system to evaluate the impact of device parameters (e.g.,wavelength-dependent fluence corrections) and tissue parameters (e.g. fluid channel depth, blood SO2, spectral coloring artifacts) on oximetry measurement accuracy. Results elucidated key challenges in PAI oximetry and device design trade-offs, which subsequently allowed for optimization of system performance. This approach provides a robust benchtop test platform that can support PAI oximetry device optimization, performance validation, and clinical translation, and may inform future development of consensus test methods for performance assessment of photoacoustic oximetry imaging systems.

  9. Oxygen measurement by multimode diode lasers employing gas correlation spectroscopy.

    Science.gov (United States)

    Lou, Xiutao; Somesfalean, Gabriel; Chen, Bin; Zhang, Zhiguo

    2009-02-10

    Multimode diode laser (MDL)-based correlation spectroscopy (COSPEC) was used to measure oxygen in ambient air, thereby employing a diode laser (DL) having an emission spectrum that overlaps the oxygen absorption lines of the A band. A sensitivity of 700 ppm m was achieved with good accuracy (2%) and linearity (R(2)=0.999). For comparison, measurements of ambient oxygen were also performed by tunable DL absorption spectroscopy (TDLAS) technique employing a vertical cavity surface emitting laser. We demonstrate that, despite slightly degraded sensitivity, the MDL-based COSPEC-based oxygen sensor has the advantages of high stability, low cost, ease-of-use, and relaxed requirements in component selection and instrument buildup compared with the TDLAS-based instrument.

  10. Measurement of oxygen thermomigration in a hypostoichiometric mixed oxide

    International Nuclear Information System (INIS)

    Norris, D.I.R.; Coleman, S.C.; Kay, P.

    1978-08-01

    A method of determining oxygen to metal ratios in hypostoichiometric (U, Ce)Osub(2-x) by means of lattice parameter measurement and its application to thermomigration experiments is described. The technique is shown to compare favourably with other methods when a simple structure prevails. It is found that oxygen redistributes down an imposed temperature gradient, confirming theoretical predictions, and that the measured Arrhenius slope decreases as the cerium valency decreases. This effect is more marked than in (U, Pu)Osub(2-x). The results are attributable to solid state transport of oxygen vacancies and suggest that immobile complexes incorporating some oxygen deficiency are more easily formed in (U, Ce)Osub(2-x) than in (U, Pu)Osub(2-x). (author)

  11. Projections of climate-driven changes in tuna vertical habitat based on species-specific differences in blood oxygen affinity.

    Science.gov (United States)

    Mislan, K A S; Deutsch, Curtis A; Brill, Richard W; Dunne, John P; Sarmiento, Jorge L

    2017-10-01

    Oxygen concentrations are hypothesized to decrease in many areas of the ocean as a result of anthropogenically driven climate change, resulting in habitat compression for pelagic animals. The oxygen partial pressure, pO 2 , at which blood is 50% saturated (P 50 ) is a measure of blood oxygen affinity and a gauge of the tolerance of animals for low ambient oxygen. Tuna species display a wide range of blood oxygen affinities (i.e., P 50 values) and therefore may be differentially impacted by habitat compression as they make extensive vertical movements to forage on subdaily time scales. To project the effects of end-of-the-century climate change on tuna habitat, we calculate tuna P 50 depths (i.e., the vertical position in the water column at which ambient pO 2 is equal to species-specific blood P 50 values) from 21st century Earth System Model (ESM) projections included in the fifth phase of the Climate Model Intercomparison Project (CMIP5). Overall, we project P 50 depths to shoal, indicating likely habitat compression for tuna species due to climate change. Tunas that will be most impacted by shoaling are Pacific and southern bluefin tunas-habitat compression is projected for the entire geographic range of Pacific bluefin tuna and for the spawning region of southern bluefin tuna. Vertical shifts in P 50 depths will potentially influence resource partitioning among Pacific bluefin, bigeye, yellowfin, and skipjack tunas in the northern subtropical and eastern tropical Pacific Ocean, the Arabian Sea, and the Bay of Bengal. By establishing linkages between tuna physiology and environmental conditions, we provide a mechanistic basis to project the effects of anthropogenic climate change on tuna habitats. Published 2017. This article is a U.S. Government work and is in the public domain in the USA.

  12. Zolpidem reduces the blood oxygen level-dependent signal during visual system stimulation.

    Science.gov (United States)

    Licata, Stephanie C; Lowen, Steven B; Trksak, George H; Maclean, Robert R; Lukas, Scott E

    2011-08-15

    Zolpidem is a short-acting imidazopyridine hypnotic that binds at the benzodiazepine binding site on specific GABA(A) receptors to enhance fast inhibitory neurotransmission. The behavioral and receptor pharmacology of zolpidem has been studied extensively, but little is known about its neuronal substrates in vivo. In the present within-subject, double-blind, and placebo-controlled study, blood oxygen level-dependent functional magnetic resonance imaging (BOLD fMRI) at 3 Tesla was used to assess the effects of zolpidem within the brain. Healthy participants (n=12) were scanned 60 min after acute oral administration of zolpidem (0, 5, 10, or 20mg), and changes in BOLD signal were measured in the visual cortex during presentation of a flashing checkerboard. Heart rate and oxygen saturation were monitored continuously throughout the session. Zolpidem (10 and 20mg) reduced the robust visual system activation produced by presentation of this stimulus, but had no effects on physiological activity during the fMRI scan. Zolpidem's modulation of the BOLD signal within the visual cortex is consistent with the abundant distribution of GABA(A) receptors localized in this region, as well as previous studies showing a relationship between increased GABA-mediated neuronal inhibition and a reduction in BOLD activation. Copyright © 2011 Elsevier Inc. All rights reserved.

  13. Zolpidem reduces the blood oxygen level-dependent signal during visual system stimulation

    Science.gov (United States)

    Licata, Stephanie C.; Lowen, Steven B.; Trksak, George H.; MacLean, Robert R.; Lukas, Scott E.

    2011-01-01

    Zolpidem is a short-acting imidazopyridine hypnotic that binds at the benzodiazepine binding site on specific GABAA receptors to enhance fast inhibitory neurotransmission. The behavioral and receptor pharmacology of zolpidem has been studied extensively, but little is known about its neuronal substrates in vivo. In the present within-subject, double-blind, and placebo-controlled study, blood oxygen level-dependent functional magnetic resonance imaging (BOLD fMRI) at 3 Tesla was used to assess the effects of zolpidem within the brain. Healthy participants (n=12) were scanned 60 minutes after acute oral administration of zolpidem (0, 5, 10, or 20 mg), and changes in BOLD signal were measured in the visual cortex during presentation of a flashing checkerboard. Heart rate and oxygen saturation were monitored continuously throughout the session. Zolpidem (10 and 20 mg) reduced the robust visual system activation produced by presentation of this stimulus, but had no effects on physiological activity during the fMRI scan. Zolpidem’s modulation of the BOLD signal within the visual cortex is consistent with the abundant distribution of GABAA receptors localized in this region, as well as previous studies showing a relationship between increased GABA-mediated neuronal inhibition and a reduction in BOLD activation. PMID:21640782

  14. Correlation of oxygenation and perfusion sensitive MRI with invasive micro probe measurements in healthy mice brain

    International Nuclear Information System (INIS)

    Sedlacik, Jan; Fiehler, Jens; Reitz, Matthias; Schmidt, Nils O.; Bolar, Divya S.; Adalsteinsson, Elfar

    2015-01-01

    The non-invasive assessment of (patho-)physiological parameters such as, perfusion and oxygenation, is of great importance for the characterization of pathologies e.g., tumors, which may be helpful to better predict treatment response and potential outcome. To better understand the influence of physiological parameters on the investigated oxygenation and perfusion sensitive MRI methods, MRI measurements were correlated with subsequent invasive micro probe measurements during free breathing conditions of air, air+10% CO2 and 100% O2 in healthy mice brain. MRI parameters were the irreversible (R2), reversible (R2') and effective (R2*) transverse relaxation rates, venous blood oxygenation level assessed by quantitative blood oxygenation level dependent (qBOLD) method and cerebral blood flow (CBF) assessed by arterial spin labeling (ASL) using a 7T small animal MRI scanner. One to two days after MRI, tissue perfusion and pO2 were measured by Laser-Doppler flowmetry and fluorescence quenching micro probes, respectively. The tissue pO2 values were converted to blood oxygen saturation by using the Hill equation. The animals were anesthetized by intra peritoneal injection of ketamine-xylazine-acepromazine (10-2-0.3 mg/ml.kg). Results for normal/hypercapnia/hyperoxia conditions were: R2[s and -1] = 20.7/20.4/20.1, R2*[s and -1] = 31.6/29.6/25.9, R2'[s and 1] = 10.9/9.2/5.7, qBOLD venous blood oxygenation level = 0.43/0.51/0.56, CBF[ml.min and -1.100g and -1] = 70.6/105.5/81.8, Laser-Doppler flowmetry[a.u.] = 89.2/120.2/90.6 and pO2[mmHg] = 6.3/32.3/46.7. All parameters were statistically significantly different with P < 0.001 between all breathing conditions. All MRI and the corresponding micro probe measurements were also statistically significantly (P ≤ 0.03) correlated with each other. However, converting the tissue pO2 to blood oxygen saturation = 0.02/0.34/0.63, showed only very limited agreement with the qBOLD venous blood oxygenation level. We found good

  15. Correlation of oxygenation and perfusion sensitive MRI with invasive micro probe measurements in healthy mice brain

    Energy Technology Data Exchange (ETDEWEB)

    Sedlacik, Jan; Fiehler, Jens [University Medical Center Hamburg-Eppendorf, Hamburg (Germany). Neuroradiology; Reitz, Matthias; Schmidt, Nils O. [University Medical Center Hamburg-Eppendorf, Hamburg (Germany). Neurosurgery; Bolar, Divya S. [Massachusetts General Hospital, Athinoula A. Martinos Center for Biomedical Imaging, Charlestown, MA (United States). Radiology; Adalsteinsson, Elfar [Massachusetts Institute of Technology, Cambridge, MA (United States). Electrical Engineering and Computer Science

    2015-05-01

    The non-invasive assessment of (patho-)physiological parameters such as, perfusion and oxygenation, is of great importance for the characterization of pathologies e.g., tumors, which may be helpful to better predict treatment response and potential outcome. To better understand the influence of physiological parameters on the investigated oxygenation and perfusion sensitive MRI methods, MRI measurements were correlated with subsequent invasive micro probe measurements during free breathing conditions of air, air+10% CO2 and 100% O2 in healthy mice brain. MRI parameters were the irreversible (R2), reversible (R2') and effective (R2*) transverse relaxation rates, venous blood oxygenation level assessed by quantitative blood oxygenation level dependent (qBOLD) method and cerebral blood flow (CBF) assessed by arterial spin labeling (ASL) using a 7T small animal MRI scanner. One to two days after MRI, tissue perfusion and pO2 were measured by Laser-Doppler flowmetry and fluorescence quenching micro probes, respectively. The tissue pO2 values were converted to blood oxygen saturation by using the Hill equation. The animals were anesthetized by intra peritoneal injection of ketamine-xylazine-acepromazine (10-2-0.3 mg/ml.kg). Results for normal/hypercapnia/hyperoxia conditions were: R2[s {sup and} -1] = 20.7/20.4/20.1, R2*[s {sup and} -1] = 31.6/29.6/25.9, R2'[s {sup and} 1] = 10.9/9.2/5.7, qBOLD venous blood oxygenation level = 0.43/0.51/0.56, CBF[ml.min {sup and} -1.100g {sup and} -1] = 70.6/105.5/81.8, Laser-Doppler flowmetry[a.u.] = 89.2/120.2/90.6 and pO2[mmHg] = 6.3/32.3/46.7. All parameters were statistically significantly different with P < 0.001 between all breathing conditions. All MRI and the corresponding micro probe measurements were also statistically significantly (P ≤ 0.03) correlated with each other. However, converting the tissue pO2 to blood oxygen saturation = 0.02/0.34/0.63, showed only very limited agreement with the qBOLD venous blood

  16. Haptoglobin blood test

    Science.gov (United States)

    The haptoglobin blood test measures the level of haptoglobin in your blood. Haptoglobin is a protein produced by the liver. It attaches to a certain type of hemoglobin in the blood. Hemoglobin is a blood cell that carries oxygen.

  17. Assessing the impacts of deoxygenation on marine species using blood-oxygen binding thresholds as proxies for hypoxia tolerance in the water column

    Science.gov (United States)

    Smith-Mislan, A.; Deutsch, C.; Dunne, J. P.; Sarmiento, J. L.

    2016-02-01

    Oxygen and temperature decrease, often rapidly, from shallow to deeper depths, restricting the ability of marine species to use the vertical habitat. One physiological trait that determines the tolerance of organisms to low oxygen is the oxygen affinity of respiratory pigments, hemoglobin and hemocyanin, in the blood. Oxygen affinity is sensitive to temperature because the reversible reaction between oxygen and blood pigments absorbs or releases energy, called the heat of oxygenation. To quantify the range of oxygen affinities for marine species, we surveyed the literature for measurements of oxygen binding to blood at multiple temperatures. Oxygen affinity is mapped within the ocean environment using the depth at which oxygen pressure decreases to the point at which the blood is 50% oxygenated (P50 depth) as organisms move from the surface to depth in the ocean water column. We calculate P50 depths for hydrographic observations and model simulations and find that vertical gradients in both temperature and oxygen impact the vertical position and areal extent of P50 depths. Shifts in P50 due to temperature cause physiological types with the same P50 in the surface ocean to have different P50 depths and physiological types with different P50's in the surface ocean to have the same P50 depth. The vertical distances between P50 depths are spatially variable, which may determine the frequency of ecological interactions, such as competition and predation. P50 depths provide new insights into the historical and future impacts of changing hypoxic zones on species living in pelagic habitats.

  18. Skin perfusion pressure measured by isotope washout in legs with arterial occlusive disease. Evaluation of different tracers, comparison to segmental systolic pressure, angiography and transcutaneous oxygen tension and variations during changes in systemic blood pressure

    DEFF Research Database (Denmark)

    Holstein, P; Trap-Jensen, J; Bagger, H

    1983-01-01

    Hg (range 18-98) (P less than 0.02). The average washout constant for the three different tracers were approximately equal and correlated statistically significant with the SPP; (2) In 59 legs with AOD, segmental SPP was compared to segmental systolic blood pressures on the thigh, calf, ankle and first...... digit (strain gauge technique). The two different methods correlated statistically significant at all four levels, but the systolic blood pressures were higher than the SPP in particular in diabetic legs; (3) Angiograms in 35 legs with AOD showed that the SPP on the ankle was only consistently decreased...

  19. Decreased muscle oxygenation and increased arterial blood flow in the non-exercising limb during leg exercise.

    Science.gov (United States)

    Shiroishi, Kiyoshi; Kime, Ryotaro; Osada, Takuya; Murase, Norio; Shimomura, Kousuke; Katsumura, Toshihito

    2010-01-01

    We evaluated arterial blood flow, muscle tissue oxygenation and muscle metabolism in the non-exercising limb during leg cycling exercise. Ten healthy male volunteers performed a graded leg cycling exercise at 0, 40, 80, 120 and 160 watts (W) for 5 min each. Tissue oxygenation index (TOI) of the non-exercising left forearm muscle was measured using a near-infrared spatially resolved spectroscopy (NIR(SRS)), and non-exercising forearm blood flow ((NONEX)FBF) in the brachial artery was also evaluated by a Doppler ultrasound system. We also determined O(2) consumption of the non-exercising forearm muscle (NONEXV(O)(2mus)) by the rate of decrease in O(2)Hb during arterial occlusion at each work rate. TOI was significantly decreased at 160 W (p exercising muscle may be reduced, even though (NONEX)FBF increases at high work rates during leg cycling exercise.

  20. Correlation of oxygenation and perfusion sensitive MRI with invasive micro probe measurements in healthy mice brain.

    Science.gov (United States)

    Sedlacik, Jan; Reitz, Matthias; Bolar, Divya S; Adalsteinsson, Elfar; Schmidt, Nils O; Fiehler, Jens

    2015-03-01

    The non-invasive assessment of (patho-)physiological parameters such as, perfusion and oxygenation, is of great importance for the characterization of pathologies e.g., tumors, which may be helpful to better predict treatment response and potential outcome. To better understand the influence of physiological parameters on the investigated oxygenation and perfusion sensitive MRI methods, MRI measurements were correlated with subsequent invasive micro probe measurements during free breathing conditions of air, air+10% CO2 and 100% O2 in healthy mice brain. MRI parameters were the irreversible (R2), reversible (R2') and effective (R2*) transverse relaxation rates, venous blood oxygenation level assessed by quantitative blood oxygenation level dependent (qBOLD) method and cerebral blood flow (CBF) assessed by arterial spin labeling (ASL) using a 7 T small animal MRI scanner. One to two days after MRI, tissue perfusion and pO2 were measured by Laser-Doppler flowmetry and fluorescence quenching micro probes, respectively. The tissue pO2 values were converted to blood oxygen saturation by using the Hill equation. The animals were anesthetized by intra peritoneal injection of ketamine-xylazine-acepromazine (10-2-0.3 mg/ml · kg). Results for normal/hypercapnia/hyperoxia conditions were: R2[s(∧)-1] = 20.7/20.4/20.1, R2*[s(∧)-1] = 31.6/29.6/25.9, R2'[s-(∧)1] = 10.9/9.2/5.7, qBOLD venous blood oxygenation level = 0.43/0.51/0.56, CBF[ml · min(∧)-1 · 100 g(∧)-1] = 70.6/105.5/81.8, Laser-Doppler flowmetry[a.u.] = 89.2/120.2/90.6 and pO2[mmHg] = 6.3/32.3/46.7. All parameters were statistically significantly different with P effects of anesthesia and trauma due to micro probe insertion are strong confounding factors and need close attention for study planning and conduction of experiments. Investigation of the correlation of perfusion and oxygenation sensitive MRI methods with micro probe measurements in pathologic tissue such as tumors is now of compelling interest

  1. Microscopic oxygen imaging based on fluorescein bleaching efficiency measurements

    DEFF Research Database (Denmark)

    Beutler, Martin; Heisterkamp, Ines M.; Piltz, Bastian

    2014-01-01

    by a charge-coupled-device (ccd) camera mounted on a fluorescence microscope allowed a pixelwise estimation of the ratio function in a microscopic image. Use of a microsensor and oxygen-consuming bacteria in a sample chamber enabled the calibration of the system for quantification of absolute oxygen......Photobleaching of the fluorophore fluorescein in an aqueous solution is dependent on the oxygen concentration. Therefore, the time-dependent bleaching behavior can be used to measure of dissolved oxygen concentrations. The method can be combined with epi-fluorescence microscopy. The molecular...... states of the fluorophore can be expressed by a three-state energy model. This leads to a set of differential equations which describe the photobleaching behavior of fluorescein. The numerical solution of these equations shows that in a conventional wide-field fluorescence microscope, the fluorescence...

  2. Hypoxia, color vision deficiencies, and blood oxygen saturation.

    Science.gov (United States)

    2013-11-01

    Chromatic thresholds were measured using the Cambridge Color Test (CCT), Color Assessment and Diagnosis : (CAD) test, and Cone Specific Contrast Test at ground and 3780 m (12,400 ft) for subjects with normal color : vision and red-green color vision ...

  3. Non-invasive evaluation of blood oxygen saturation and hematocrit from T1 and T2 relaxation times: In-vitro validation in fetal blood.

    Science.gov (United States)

    Portnoy, Sharon; Seed, Mike; Sled, John G; Macgowan, Christopher K

    2017-12-01

    We propose an analytical method for calculating blood hematocrit (Hct) and oxygen saturation (sO 2 ) from measurements of its T 1 and T 2 relaxation times. Through algebraic substitution, established two-compartment relationships describing R1=T1-1 and R2=T2-1 as a function of hematocrit and oxygen saturation were rearranged to solve for Hct and sO 2 in terms of R 1 and R 2 . Resulting solutions for Hct and sO 2 are the roots of cubic polynomials. Feasibility of the method was established by comparison of Hct and sO 2 estimates obtained from relaxometry measurements (at 1.5 Tesla) in cord blood specimens to ground-truth values obtained by blood gas analysis. Monte Carlo simulations were also conducted to assess the effect of T 1 , T 2 measurement uncertainty on precision of Hct and sO 2 estimates. Good agreement was observed between estimated and ground-truth blood properties (bias = 0.01; 95% limits of agreement = ±0.13 for Hct and sO 2 ). Considering the combined effects of biological variability and random measurement noise, we estimate a typical uncertainty of ±0.1 for Hct, sO 2 estimates. Results demonstrate accurate quantification of Hct and sO 2 from T 1 and T 2 . This method is applicable to noninvasive fetal vessel oximetry-an application where existing oximetry devices are unusable or require risky blood-sampling procedures. Magn Reson Med 78:2352-2359, 2017. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

  4. Apparatus for simultaneously measuring electrical conductivity and oxygen fugacity

    Energy Technology Data Exchange (ETDEWEB)

    Netherton, R.; Duba, A.

    1978-01-31

    Electrical conductivity studies of silicates are useful in determining temperature vs depth in the earth. Realistic laboratory measurements of conduction mechanisms require that exact determinations of oxygen fugacity (fo{sub 2}) be made in the experimental environment. An apparatus is described that monitors system fo{sub 2} with a calcia-doped zirconia-oxygen cell while measuring electrical conductivity of iron-bearing silicates at high temperature (greater than 1000 K). The fo{sub 2} calculated thermodynamically from CO/CO{sub 2} mixing ratios agreed well with measurements made with the zirconia cell at 1473 K, except for fo{sub 2} greater than 10{sup -4} Pa, where, on a log{sub 10} scale, mixing-ratio errors were as large as +- 0.2. These errors are attributed to oxygen contamination in the CO{sub 2} and to mobile carbon deposits that formed in the apparatus.

  5. A new method to measure local oxygen consumption in human skeletal muscle during dynamic exercise using near-infrared spectroscopy

    International Nuclear Information System (INIS)

    Binzoni, Tiziano; Cooper, Chris E; Wittekind, Anna L; Beneke, Ralph; Elwell, Clare E; Leung, Terence S; Van De Ville, Dimitri

    2010-01-01

    Near infrared spectroscopy (NIRS) can readily report on changes in blood volume and oxygenation. However, it has proved more problematic to measure real-time changes in blood flow and oxygen consumption. Here we report the development of a novel method using NIRS to measure local oxygen consumption in human muscle. The method utilizes the blood volume changes induced by the muscle pump during rhythmically contracting exercising skeletal muscle. We found that the saturation of the blood during the contraction phase was lower than that during the relaxation phase. The calculated oxygen drop was then divided by the contraction time to generate a value for the muscle oxygen consumption in the optical region of interest. As a test we measured the muscle oxygen consumption in the human vastus lateralis during exercise on a cycle ergometer by 11 trained male athletes (32 ± 11 years old) at 40% and 110% peak aerobic power. We saw an increase from 13.78 µmol 100 g −1 min −1 to 19.72 µmol 100 g −1 min −1 with the increase in power. The measurements are theoretically exempt from usual NIRS confounders such as myoglobin and adipose tissue and could provide a useful tool for studying human physiology

  6. Method of measuring blood flow by radiation

    International Nuclear Information System (INIS)

    Gildenberg, P.L.

    1977-01-01

    A method of measuring relative blood flow through at least a part of the body using penetrating radiation comprises transmitting a plurality of rays at an initial angle or initial mean angle through a planar slice of the body to define a first set of rays, transmitting a plurality of further sets of rays at angles or mean angles different from each other and from the initial angle or initial mean angle through the same planar slice of the body to define by the intersection of all such rays a two-dimensional matrix of elements of the body in the slice, measuring for each ray emerging from the body a number of over the period of time at least equal to a pulse interval representing the momentary sum of the transmissions or absorptions of the element of the body intersected by the ray, determining from the momentary signals momentary signals a difference signal representing the maximum difference between the momentary signals for each ray over the period of time, deriving sets of discrete difference signals corresponding to the sets of rays, the difference signals being indicative of the transmission or absorption of blood flowing through each element of the body in the matrix, and calculating from the difference signals resultant signals representing the transmissions or absorptions due to blood flow in the elements of the matrix. These resultant signals may be visually depicted on a cathode ray tube display, as a digital print-out, or as a photograph. 30 claims, 8 figures

  7. The dual roles of red blood cells in tissue oxygen delivery

    DEFF Research Database (Denmark)

    Jensen, Frank Bo

    2009-01-01

    Vertebrate red blood cells (RBCs) seem to serve tissue oxygen delivery in two distinct ways. Firstly, RBCs enable the adequate transport of O2 between respiratory surfaces and metabolizing tissues by means of their high intracellular concentration of hemoglobin (Hb), appropriate allosteric...

  8. Near-infrared spectroscopy determined cerebral oxygenation with eliminated skin blood flow in young males

    DEFF Research Database (Denmark)

    Hirasawa, Ai; Kaneko, Takahito; Tanaka, Naoki

    2016-01-01

    We estimated cerebral oxygenation during handgrip exercise and a cognitive task using an algorithm that eliminates the influence of skin blood flow (SkBF) on the near-infrared spectroscopy (NIRS) signal. The algorithm involves a subtraction method to develop a correction factor for each subject. ...

  9. Intraoperative changes of transcranial Doppler velocity: relation to arterial oxygen content and whole-blood viscosity

    NARCIS (Netherlands)

    Schuurman, P. R.; Albrecht, K. W.

    1999-01-01

    The association of arterial oxygen content (CaO2) and viscosity with transcranial Doppler (TCD) blood flow velocity in the middle cerebral artery was studied in 20 adults without cerebrovascular disease undergoing abdominal surgery associated with significant fluctuations in hematology. TCD

  10. A technique for measuring oxygen saturation in biological tissues based on diffuse optical spectroscopy

    Science.gov (United States)

    Kleshnin, Mikhail; Orlova, Anna; Kirillin, Mikhail; Golubiatnikov, German; Turchin, Ilya

    2017-07-01

    A new approach to optical measuring blood oxygen saturation was developed and implemented. This technique is based on an original three-stage algorithm for reconstructing the relative concentration of biological chromophores (hemoglobin, water, lipids) from the measured spectra of diffusely scattered light at different distances from the probing radiation source. The numerical experiments and approbation of the proposed technique on a biological phantom have shown the high reconstruction accuracy and the possibility of correct calculation of hemoglobin oxygenation in the presence of additive noise and calibration errors. The obtained results of animal studies have agreed with the previously published results of other research groups and demonstrated the possibility to apply the developed technique to monitor oxygen saturation in tumor tissue.

  11. Intra-dialytic blood oxygen saturation (SO2): association with dialysis hypotension (the SOGLIA Study).

    Science.gov (United States)

    Mancini, E; Perazzini, C; Gesualdo, L; Aucella, F; Limido, A; Scolari, F; Savoldi, S; Tramonti, M; Corazza, L; Atti, M; Severi, S; Bolasco, P; Santoro, A

    2017-12-01

    Intradialytic hypotension (IDH) has a dramatic impact on the main outcomes of dialysis patients. Early warning of hemodynamic worsening during dialysis would enable preventive measures to be taken. Blood oxygen saturation (SO 2 ) is used for hemodynamic monitoring in the critical care setting and may provide useful information about IDH onset. To evaluate whether short- and medium-term variations in the SO 2 signal (ST-SO 2var , MT-SO 2var ,) during dialysis are a predictor of IDH. In this 3-month observational cohort study, 51 hypotension-prone chronic hemodialysis (HD) patients, with vascular access by arteriovenous fistula (AVF) or central venous catheter (CVC), were enrolled. Continuous non-invasive blood SO 2 was monitored (fc = 0.2 Hz) by an optical sensor on the arterial line of the extracorporeal circulation; blood pressure (every 30 min), symptoms and their time of appearance were noted. Predictive power of IDH was expressed by the area under curve (AUC) sensitivity and specificity based on intradialytic variations in SO 2 . A total of 1290 HD sessions were analyzed. Overall, off-line ST-SO 2var analysis proved able to correctly predict IDH in 67 % of the sessions where IDH occurred. The best predictive performance was found in the presence of highly arterialized AVF (SO 2  > 95 %) (75 % sensitivity; AUC 0.825; p < 0.05). On the contrary, in sessions with CVC, IDH prediction proved more efficient by MT-SO 2var (AUC 0.575; p = 0.01). Intradialytic SO 2 variability could be a valid parameter to detect in advance the hemodynamic worsening that precedes IDH. Appropriate timely intervention could help prevent IDH onset.

  12. BLOOD SUBSTITUTES: EVOLUTION FROM NON-CARRYING TO OXYGEN AND GAS CARRYING FLUIDS

    Science.gov (United States)

    Cabrales, Pedro; Intaglietta, Marcos

    2013-01-01

    The development of oxygen (O2) carrying blood substitutes has evolved from the goal of replicating blood O2 transports properties to that of preserving microvascular and organ function, reducing the inherent or potential toxicity of the material used to carry O2, and treating pathologies initiated by anemia and hypoxia. Furthermore, the emphasis has shifted from blood replacement fluid to “O2 therapeutics” that restore tissue oxygenation to specific tissues regions. This review covers the different alternatives, potential and limitations of hemoglobin based O2 carriers (HBOCs) and perfluorocarbon based O2 carriers (PFCOCs), with emphasis on the physiological conditions disturbed in the situation that they will be used. It describes how concepts learned from plasma expanders without O2 carrying capacity can be applied to maintain O2 delivery and summarizes the microvascular responses due to HBOCs and PFCOCs. This review also presents alternative applications of HBOCs and PFCOCs namely: 1) How HBOC O2 affinity can be engineered to target O2 delivery to hypoxic tissues; and 2) How the high gas solubility of PFCOCs provides new opportunities for carrying, dissolving and delivering gases with biological activity. It is concluded that current blood substitutes development has amplified their applications horizon by devising therapeutic functions for oxygen carriers requiring limited O2 delivery capacity restoration. Conversely, full, blood-like O2 carrying capacity re-establishment awaits control of O2 carrier toxicity. PMID:23820271

  13. Oxygen tension measurements of tumors growing in mice

    International Nuclear Information System (INIS)

    Adam, Markus F.; Dorie, Mary Jo; Brown, J. Martin

    1999-01-01

    Purpose: Clinical studies using the Eppendorf histograph have shown that patients whose tumors have a low pO 2 have worse local control after radiotherapy, and have higher metastatic rates. Because preclinical studies of methods of overcoming, or exploiting, hypoxia generally use transplanted tumors in mice, we have compared the oxygenation of mouse tumors with human tumors to determine the appropriateness of the transplanted mouse model for such preclinical studies. Methods and Materials: We evaluated the oxygenation status of subcutaneous (s.c.) tissue and of 12 intradermally (i.d.)- and 7 s.c.-growing mouse or human transplanted tumors in mice using the Eppendorf histograph, and compared the values obtained with measurements of human head and neck nodes. Results: The normal tissue pO 2 profile of air-breathing mice showed a nearly Gaussian distribution (38.2 ± 14.9 mmHg). Breathing 10% O 2 or carbogen resulted in dramatic changes in normal tissue oxygenation. Tumors growing intradermally in the back of air-breathing mice were extremely hypoxic and resistant to expected changes in oxygenation (carbogen breathing, size, and use of anesthetics). Tumors growing s.c. in the foot showed higher oxygen profiles with marked changes in oxygenation when exposing the animals to different levels of oxygen. However, the oxygenation of the mouse tumors transplanted in either site was only a fraction of that of the majority of human tumors. Conclusion: Experimental mouse tumors are markedly hypoxic, with median values of 10-20% of those of human tumors. Hence, mouse tumors are probably good models for the most hypoxic human tumors that respond poorly to radiotherapy; however, caution has to be exercised in extrapolating data from mouse to man

  14. Effects of acetazolamide on cerebral blood flow and brain tissue oxygenation

    DEFF Research Database (Denmark)

    Lassen, N A; Friberg, L; Kastrup, J

    1987-01-01

    Oral administration of 1 g of acetazolamide to 8 normal subjects studied at sea level and in normoxia caused an acute increase in cerebral blood flow (CBF). During the subsequent prolonged oral treatment with 1 g of acetazolamide daily, CBF returned to normal within 2 days. The alveolar CO2 tension...... decreased gradually to 70% of the control value, indicating hyperventilation. At sea level hyperventilation will not increase brain oxygenation significantly in normal man, as the arterial oxygen content only increases minimally, while CBF is unchanged. At high altitude the beneficial effects...... of acetazolamide on the symptoms of acute mountain sickness may well be due to an improved oxygen supply to the brain, as hyperventilation will, at the low ambient PO2, cause a significant increase of the arterial oxygen content, while CBF presumably is unaffected by the drug. During hypoxia at high altitude...

  15. Polynomial analysis of ambulatory blood pressure measurements

    NARCIS (Netherlands)

    Zwinderman, A. H.; Cleophas, T. A.; Cleophas, T. J.; van der Wall, E. E.

    2001-01-01

    In normotensive subjects blood pressures follow a circadian rhythm. A circadian rhythm in hypertensive patients is less well established, and may be clinically important, particularly with rigorous treatments of daytime blood pressures. Polynomial analysis of ambulatory blood pressure monitoring

  16. Changes in Oxygen Partial Pressure in the Vitreous Body and Arterial Blood of Rabbits Depending on Oxygen Concentration in Inspired Mixture.

    Science.gov (United States)

    Amkhanitskaya, L I; Nikolaeva, G V; Sokolova, N A

    2015-07-01

    We demonstrated that the vitreous body of one-month-old rabbits becomes a "reservoir" for storage and accumulation of oxygen after exposure to additional oxygenation of the organism (O2 concentrations in inspired gas mixture were 40, 60, 85, and 99%). The higher was O2 concentration in inspired mixture, the higher was oxygen saturation of the blood and vitreous body. O2 concentration of 40% was relatively safe for eye tissues. O2 concentration >60% induced oxygen accumulation in the vitreous body, which can be a provoking factor for the development of oxygen-induced pathologies.

  17. Hybrid Optical Unobtrusive Blood Pressure Measurements

    Directory of Open Access Journals (Sweden)

    Guangfei Zhang

    2017-07-01

    Full Text Available Blood pressure (BP is critical in diagnosing certain cardiovascular diseases such as hypertension. Some previous studies have proved that BP can be estimated by pulse transit time (PTT calculated by a pair of photoplethysmography (PPG signals at two body sites. Currently, contact PPG (cPPG and imaging PPG (iPPG are two feasible ways to obtain PPG signals. In this study, we proposed a hybrid system (called the ICPPG system employing both methods that can be implemented on a wearable device, facilitating the measurement of BP in an inconspicuous way. The feasibility of the ICPPG system was validated on a dataset with 29 subjects. It has been proved that the ICPPG system is able to estimate PTT values. Moreover, the PTT measured by the new system shows a correlation on average with BP variations for most subjects, which could facilitate a new generation of BP measurement using wearable and mobile devices.

  18. Somatosensory evoked changes in cerebral oxygen consumption measured non-invasively in premature neonates

    Science.gov (United States)

    Roche-Labarbe, Nadege; Fenoglio, Angela; Radakrishnan, Harsha; Kocienski-Filip, Marcia; Carp, Stefan A.; Dubb, Jay; Boas, David A.; Grant, P. Ellen; Franceschini, Maria Angela

    2013-01-01

    The hemodynamic functional response is used as a reliable marker of neuronal activity in countless studies of brain function and cognition. In newborns and infants, however, conflicting results have appeared in the literature concerning the typical response, and there is little information on brain metabolism and functional activation. Measurement of all hemodynamic components and oxygen metabolism is critical for understanding neurovascular coupling in the developing brain. To this end, we combined multiple near infrared spectroscopy techniques to measure oxy- and deoxy-hemoglobin concentrations, cerebral blood volume (CBV), and relative cerebral blood flow (CBF) in the somatosensory cortex of 6 preterm neonates during passive tactile stimulation of the hand. By combining these measures we estimated relative changes in the cerebral metabolic rate of oxygen consumption (rCMRO2). CBF starts increasing immediately after stimulus onset, and returns to baseline before blood volume. This is consistent with the model of pre-capillary arteriole active dilation driving the CBF response, with a subsequent CBV increase influenced by capillaries and veins dilating passively to accommodate the extra blood. rCMRO2 estimated using the steady-state formulation shows a biphasic pattern: an increase immediately after stimulus onset, followed by a post-stimulus undershoot due to blood flow returning faster to baseline than oxygenation. However, assuming a longer mean transit time from the arterial to the venous compartment, due to the immature vascular system of premature infants, reduces the post-stimulus undershoot and increases the flow/consumption ratio to values closer to adult values reported in the literature. We are the first to report changes in local rCBF and rCMRO2 during functional activation in preterm infants. The ability to measure these variables in addition to hemoglobin concentration changes is critical for understanding neurovascular coupling in the developing

  19. Blood flow and tissue oxygen pressures of liver and pancreas in rats: effects of volatile anesthetics and of hemorrhage.

    Science.gov (United States)

    Vollmar, B; Conzen, P F; Kerner, T; Habazettl, H; Vierl, M; Waldner, H; Peter, K

    1992-09-01

    The object of this investigation was to compare the effects of volatile anesthetics and of hemorrhage at comparable arterial blood pressures on splanchnic blood flow (radioactive microspheres) and tissue oxygenation of the liver and pancreas (surface PO2 [PSO2] electrodes). In contrast to earlier studies, we did not use identical minimum alveolar anesthetic concentration multiples as a reference to compare volatile anesthetics; rather, we used the splanchnic perfusion pressure. Under general anesthesia (intravenous chloralose) and controlled ventilation, 12 Sprague-Dawley rats underwent laparotomy to allow access to abdominal organs. Mean arterial pressure was decreased from 84 +/- 3 mm Hg (mean +/- SEM) at control to 50 mm Hg by 1.0 +/- 0.1 vol% halothane, 2.2 +/- 0.2 vol% enflurane, and 2.3 +/- 0.1 vol% isoflurane in a randomized sequence. For hemorrhagic hypotension, blood was withdrawn gradually until a mean arterial pressure of 50 mm Hg was attained. Volatile anesthetics and hemorrhage reduced cardiac output, and hepatic arterial, portal venous, and total hepatic blood flows by comparable degrees. Mean hepatic PSO2 decreased significantly from 30.7 +/- 2.6 mm Hg at control to 17.4 +/- 2 and 17.5 +/- 2 mm Hg during enflurane and isoflurane (each P less than 0.05) anesthesia, respectively. The decrease to 11.5 +/- 2.5 mm Hg was more pronounced during halothane anesthesia. Hemorrhagic hypotension was associated with the lowest hepatic PSO2 (3.4 +/- 1.3 mm Hg) and the highest number of hypoxic (0-5 mm Hg 86%) and anoxic PSO2 values (0 mm Hg 46%). Pancreatic blood flow and oxygenation remained unchanged from control during halothane and enflurane administration, whereas isoflurane increased both variables. Hemorrhagic hypotension slightly reduced pancreatic flow (-8%) but significantly decreased PSO2 from 58 +/- 5 mm Hg at control to 36 +/- 3 mm Hg, with 7% of all measured values in the hypoxic range. Thus, volatile anesthetics preserved pancreatic but not hepatic

  20. Reactive oxygen species inactivation improves pancreatic capillary blood flow in caerulein-induced pancreatitis in rats

    Directory of Open Access Journals (Sweden)

    Meirelles Jr. Roberto Ferreira

    2003-01-01

    Full Text Available PURPOSE: Reactive oxygen species (ROS inactivation was studied to determine alterations in the pancreatic capillary blood flow (PCBF during caerulein-induced pancreatitis in rats. METHODS: A laser-Doppler flowmeter to measure PCBF and N-t-Butyl-Phenylnitrone (PBN compound to inactivate ROS were used. Forty rats were divided in groups: 1 control; 2 caerulein; 3 PBN; 4 caerulein+PBN. Serum biochemistry and histopathological analyses were performed. RESULTS: PCBF measured a mean of 109.08 ± 14.54%, 68.24 ± 10.47%, 102.18 ± 10.23% and 87.73 ± 18.72% in groups 1, 2, 3 and 4, respectively. PCBF in groups 2 and 4 decreased 31.75 ± 16.79% and 12.26 ± 15.24%, respectively. Serum amylase was 1323.70 ± 239.10 U/l, 2184.60 ± 700.46 U/l, 1379.80 ± 265.72 U/l and 1622.10 ± 314.60 U/l in groups 1, 2, 3 and 4, respectively. There was a significant difference in the PCBF and serum amylase when compared groups 2 and 4. Cytoplasmatic vacuolation was present in groups 2 and 4. Otherwise, no qualitative changes were seen. CONCLUSION: ROS inactivation improves PCBF and minimizes the serum amylase increase during caerulein-induced pancreatitis. ROS effect may be one of the leading causative events in this model of acute pancreatitis.

  1. Online Measurement of Oxygen-Dependent Enzyme Reaction Kinetics

    DEFF Research Database (Denmark)

    Meissner, Murray Peter; Nordblad, Mathias; Woodley, John M

    2018-01-01

    accurate measurement of the oxygen mass balance in the gas-phase of a reactor. The method was successfully validated and demonstrated using two model reactions: firstly the oxidation of glucose by glucose oxidase and secondly the Baeyer-Villiger oxidation of macrocyclic ketones to lactones. Initial...

  2. Novel idea to monitor and measure blood hemoglobin noninvasively ...

    African Journals Online (AJOL)

    Measuring blood hematocrit noninvasively is reviewed in this paper. Although there is an inclination to measure the hematocrit by determining the bioelectrical impedance of the blood, in vitro experimental methods still remain practically inapplicable. The blood sample size is determined when blood samples are examined.

  3. Effects of anesthetic agents on brain blood oxygenation level revealed with ultra-high field MRI.

    Directory of Open Access Journals (Sweden)

    Luisa Ciobanu

    Full Text Available During general anesthesia it is crucial to control systemic hemodynamics and oxygenation levels. However, anesthetic agents can affect cerebral hemodynamics and metabolism in a drug-dependent manner, while systemic hemodynamics is stable. Brain-wide monitoring of this effect remains highly challenging. Because T(2*-weighted imaging at ultra-high magnetic field strengths benefits from a dramatic increase in contrast to noise ratio, we hypothesized that it could monitor anesthesia effects on brain blood oxygenation. We scanned rat brains at 7T and 17.2T under general anesthesia using different anesthetics (isoflurane, ketamine-xylazine, medetomidine. We showed that the brain/vessels contrast in T(2*-weighted images at 17.2T varied directly according to the applied pharmacological anesthetic agent, a phenomenon that was visible, but to a much smaller extent at 7T. This variation is in agreement with the mechanism of action of these agents. These data demonstrate that preclinical ultra-high field MRI can monitor the effects of a given drug on brain blood oxygenation level in the absence of systemic blood oxygenation changes and of any neural stimulation.

  4. Effects of anesthetic agents on brain blood oxygenation level revealed with ultra-high field MRI

    International Nuclear Information System (INIS)

    Ciobanu, Luisa; Reynaud, Olivier; Le Bihan, Denis; Uhrig, Lynn; Jarraya, Bechir

    2012-01-01

    During general anesthesia it is crucial to control systemic hemodynamics and oxygenation levels. However, anesthetic agents can affect cerebral hemodynamics and metabolism in a drug-dependent manner, while systemic hemodynamics is stable. Brain-wide monitoring of this effect remains highly challenging. Because T2'*-weighted imaging at ultra-high magnetic field strengths benefits from a dramatic increase in contrast to noise ratio, we hypothesized that it could monitor anesthesia effects on brain blood oxygenation. We scanned rat brains at 7 T and 17.2 T under general anesthesia using different anesthetics (isoflurane, ketamine-xylazine, medetomidine). We showed that the brain/vessels contrast in T2'*- weighted images at 17.2 T varied directly according to the applied pharmacological anesthetic agent, a phenomenon that was visible, but to a much smaller extent at 7 T. This variation is in agreement with the mechanism of action of these agents. These data demonstrate that preclinical ultra-high field MRI can monitor the effects of a given drug on brain blood oxygenation level in the absence of systemic blood oxygenation changes and of any neural stimulation. (authors)

  5. Elevated global cerebral blood flow, oxygen extraction fraction and unchanged metabolic rate of oxygen in young adults with end-stage renal disease: an MRI study

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Gang; Lou, Yaxian; Pan, Zhiying; Liu, Ya [Medical School of Nanjing University, Department of Medical Imaging, Jinling Hospital, Nanjing, Jiangsu (China); Nanjing University of Aeronautics and Astronautics, College of Aivil Aviation, Nanjing, Jiangsu (China); Wen, Jiqiu; Li, Xue; Zhang, Zhe [Medical School of Nanjing University, National Clinical Research Center of Kidney Diseases, Jinling Hospital, Nanjing, Jiangsu (China); Lu, Hanzhang [University of Texas Southwestern Medical Center, Advanced Imaging Research Center, Dallas, TX (United States); Liu, Wei [Siemens Shenzhen Magnetic Resonance Ltd., Shenzhen, Guangdong (China); Liu, Hui [Siemens MR NEA Collaboration, Siemens Ltd., Shanghai (China); Chen, Huijuan; Kong, Xiang; Luo, Song; Jiang, Xiaolu; Zhang, Zongjun; Zhang, Long Jiang; Lu, Guang Ming [Medical School of Nanjing University, Department of Medical Imaging, Jinling Hospital, Nanjing, Jiangsu (China)

    2016-06-15

    To noninvasively assess global cerebral blood flow (CBF), oxygen extraction fraction (OEF) and cerebral metabolic rate of oxygen (CMRO{sub 2}) in young adults with end-stage renal disease (ESRD). Thirty-six patients and 38 healthy volunteers were included and took part in MR examinations, blood and neuropsychological tests. CBF and OEF were measured by phase-contrast and T2-relaxation-under-spin-tagging MRI techniques, respectively. CMRO{sub 2} was computed from CBF, OEF and hematocrit according to Fick's principle. Correlations were performed between MR measurements, blood biochemistry measurements and neuropsychological test scores. Compared with controls, ESRD patients had elevated CBF (72.9 ± 12.5 vs. 63.8 ± 8.5 ml min{sup -1} 100 g{sup -1}, P < 0.001), elevated OEF (47.2 ± 10.2 vs. 35.8 ± 5.4 %, P < 0.001), but unaffected CMRO{sub 2} (199.5 ± 36.4 vs. 193.8 ± 28.6 μmol O{sub 2} min{sup -1} 100 g{sup -1}, P = 0.879). Hematocrit negatively correlated with CBF (r = -0.640, P < 0.001) and OEF (r = -0.701, P < 0.001), but not with CMRO{sub 2}. Altered neuropsychological test scores of ESRD patients were associated with OEF and CBF, but not with CMRO{sub 2}. There were weak relationships between eGFR and hematocrit (r = 0.308, P = 0.068) or CBF (r = 0.318, P = 0.059). Our findings suggested that anaemic young adults with ESRD may afford higher CBF and OEF to maintain a normal CMRO{sub 2}. Despite this compensatory process, however, cognitive function was still impaired and its severity was correlated with their CBF and OEF abnormality. (orig.)

  6. Elevated global cerebral blood flow, oxygen extraction fraction and unchanged metabolic rate of oxygen in young adults with end-stage renal disease: an MRI study

    International Nuclear Information System (INIS)

    Zheng, Gang; Lou, Yaxian; Pan, Zhiying; Liu, Ya; Wen, Jiqiu; Li, Xue; Zhang, Zhe; Lu, Hanzhang; Liu, Wei; Liu, Hui; Chen, Huijuan; Kong, Xiang; Luo, Song; Jiang, Xiaolu; Zhang, Zongjun; Zhang, Long Jiang; Lu, Guang Ming

    2016-01-01

    To noninvasively assess global cerebral blood flow (CBF), oxygen extraction fraction (OEF) and cerebral metabolic rate of oxygen (CMRO 2 ) in young adults with end-stage renal disease (ESRD). Thirty-six patients and 38 healthy volunteers were included and took part in MR examinations, blood and neuropsychological tests. CBF and OEF were measured by phase-contrast and T2-relaxation-under-spin-tagging MRI techniques, respectively. CMRO 2 was computed from CBF, OEF and hematocrit according to Fick's principle. Correlations were performed between MR measurements, blood biochemistry measurements and neuropsychological test scores. Compared with controls, ESRD patients had elevated CBF (72.9 ± 12.5 vs. 63.8 ± 8.5 ml min -1 100 g -1 , P < 0.001), elevated OEF (47.2 ± 10.2 vs. 35.8 ± 5.4 %, P < 0.001), but unaffected CMRO 2 (199.5 ± 36.4 vs. 193.8 ± 28.6 μmol O 2 min -1 100 g -1 , P = 0.879). Hematocrit negatively correlated with CBF (r = -0.640, P < 0.001) and OEF (r = -0.701, P < 0.001), but not with CMRO 2 . Altered neuropsychological test scores of ESRD patients were associated with OEF and CBF, but not with CMRO 2 . There were weak relationships between eGFR and hematocrit (r = 0.308, P = 0.068) or CBF (r = 0.318, P = 0.059). Our findings suggested that anaemic young adults with ESRD may afford higher CBF and OEF to maintain a normal CMRO 2 . Despite this compensatory process, however, cognitive function was still impaired and its severity was correlated with their CBF and OEF abnormality. (orig.)

  7. Detection of Acute Tubular Necrosis Using Blood Oxygenation Level-Dependent (BOLD MRI

    Directory of Open Access Journals (Sweden)

    Frederic Bauer

    2017-12-01

    Full Text Available Background/Aims: To date, there is no imaging technique to assess tubular function in vivo. Blood oxygen level-dependent magnetic resonance imaging (BOLD MRI measures tissue oxygenation based on the transverse relaxation rate (R2*. The present study investigates whether BOLD MRI can assess tubular function using a tubule-specific pharmacological maneuver. Methods: Cross sectional study with 28 participants including 9 subjects with ATN-induced acute kidney injury (AKI, 9 healthy controls, and 10 subjects with nephron sparing tumor resection (NSS with clamping of the renal artery serving as a model of ischemia/reperfusion (I/R-induced subclinical ATN (median clamping time 15 min, no significant decrease of eGFR, p=0.14. BOLD MRI was performed before and 5, 7, and 10 min after intravenous administration of 40 mg furosemide. Results: Urinary neutrophil gelatinase-associated lipocalin was significantly higher in ATN-induced AKI and NSS subjects than in healthy controls (p=0.03 and p=0.01, respectively. Before administration of furosemide, absolute medullary R2*, cortical R2*, and medullary/cortical R2* ratio did not significantly differ between ATN-induced AKI vs. healthy controls and between NSS-I/R vs. contralateral healthy kidneys (p>0.05 each. Furosemide led to a significant decrease in the medullary and cortical R2* of healthy subjects and NSS contralateral kidneys (p<0.05 each, whereas there was no significant change of R2* in ATN-induced AKI and the NSS-I/R kidneys (p>0.05 each. Conclusion: BOLD-MRI is able to detect even mild tubular injury but necessitates a tubule-specific pharmacological maneuver, e.g. blocking the Na+-K+-2Cl- transporter by furosemide.

  8. Quantitative measurement of the cerebral blood flow

    International Nuclear Information System (INIS)

    Houdart, R.; Mamo, H.; Meric, P.; Seylaz, J.

    1976-01-01

    The value of the cerebral blood flow measurement (CBF) is outlined, its limits are defined and some future prospects discussed. The xenon 133 brain clearance study is at present the most accurate quantitative method to evaluate the CBF in different regions of the brain simultaneously. The method and the progress it has led to in the physiological, physiopathological and therapeutic fields are described. The major disadvantage of the method is shown to be the need to puncture the internal carotid for each measurement. Prospects are discussed concerning methods derived from the same general principle but using a simpler, non-traumatic way to introduce the radio-tracer, either by breathing into the lungs or intraveinously [fr

  9. Automatic Blood Pressure Measurements During Exercise

    Science.gov (United States)

    Weaver, Charles S.

    1985-01-01

    Microprocessor circuits and a computer algorithm for automatically measuring blood pressure during ambulatory monitoring and exercise stress testing have been under development at SRI International. A system that records ECG, Korotkov sound, and arm cuff pressure for off-line calculation of blood pressure has been delivered to NASA, and an LSLE physiological monitoring system that performs the algorithm calculations in real-time is being constructed. The algorithm measures the time between the R-wave peaks and the corresponding Korotkov sound on-set (RK-interval). Since the curve of RK-interval versus cuff pressure during deflation is predictable and slowly varying, windows can be set around the curve to eliminate false Korotkov sound detections that result from noise. The slope of this curve, which will generally decrease during exercise, is the inverse of the systolic slope of the brachial artery pulse. In measurements taken during treadmill stress testing, the changes in slopes of subjects with coronary artery disease were markedly different from the changes in slopes of healthy subjects. Measurements of slope and O2 consumption were also made before and after ten days of bed rest during NASA/Ames Research Center bed rest studies. Typically, the maximum rate of O2 consumption during the post-bed rest test is less than the maximum rate during the pre-bed rest test. The post-bed rest slope changes differ from the pre-bed rest slope changes, and the differences are highly correlated with the drop in the maximum rate of O2 consumption. We speculate that the differences between pre- and post-bed rest slopes are due to a drop in heart contractility.

  10. The influence of nanodiamond on the oxygenation states and micro rheological properties of human red blood cells in vitro.

    Science.gov (United States)

    Lin, Yu-Chung; Tsai, Lin-Wei; Perevedentseva, Elena; Chang, Hsin-Hou; Lin, Ching-Hui; Sun, Der-Shan; Lugovtsov, Andrei E; Priezzhev, Alexander; Mona, Jani; Cheng, Chia-Liang

    2012-10-01

    Nanodiamond has been proven to be biocompatible and proposed for various biomedical applications. Recently, nanometer-sized diamonds have been demonstrated as an effective Raman/fluorescence probe for bio-labeling, as well as, for drug delivery. Bio-labeling/drug delivery can be extended to the human blood system, provided one understands the interaction between nanodiamonds and the blood system. Here, the interaction of nanodiamonds (5 and 100 nm) with human red blood cells (RBC) in vitro is discussed. Measurements have been facilitated using Raman spectroscopy, laser scanning fluorescence spectroscopy, and laser diffractometry (ektacytometry). Data on cell viability and hemolytic analysis are also presented. Results indicate that the nanodiamonds in the studied condition do not cause hemolysis, and the cell viability is not affected. Importantly, the oxygenation/deoxygenation process was not found to be altered when nanodiamonds interacted with the RBC. However, the nanodiamond can affect some RBC properties such as deformability and aggregation in a concentration dependent manner. These results suggest that the nanodiamond can be used as an effective bio-labeling and drug delivery tool in ambient conditions, without complicating the blood's physiological conditions. However, controlling the blood properties including deformability of RBCs and rheological properties of blood is necessary during treatment.

  11. Oxygenation measurement by multi-wavelength oxygen-dependent phosphorescence and delayed fluorescence: catchment depth and application in intact heart

    NARCIS (Netherlands)

    Balestra, Gianmarco M.; Aalders, Maurice C. G.; Specht, Patricia A. C.; Ince, Can; Mik, Egbert G.

    2015-01-01

    Oxygen delivery and metabolism represent key factors for organ function in health and disease. We describe the optical key characteristics of a technique to comprehensively measure oxygen tension (PO(2)) in myocardium, using oxygen-dependent quenching of phosphorescence and delayed fluorescence of

  12. The measurement of oxygen in vivo using EPR techniques

    International Nuclear Information System (INIS)

    Swartz, Harold M.; Clarkson, Robert B.

    1998-01-01

    The measurement of pO 2 in vivo using EPR has some features which have already led to very useful applications and this approach is likely to have increasingly wide and effective use. It is based on the effect of oxygen on EPR spectra which provides a sensitive and accurate means to measure pO 2 quantitatively. The development of oxygen-sensitive paramagnetic materials which are very stable, combined with instrumental developments, has been crucial to the in vivo applications of this technique. The physical basis and biological applications of in vivo EPR oximetry are reviewed, with particular emphasis on the use of EPR spectroscopy at 1 GHz using particulate paramagnetic materials for the repetitive and non-invasive measurement of pO 2 in tissues. In vivo EPR has already produced some very useful results which have contributed significantly to solving important biological problems. The characteristics of EPR oximetry which appear to be especially useful are often complementary to existing techniques for measuring oxygen in tissues. These characteristics include the capability of making repeated measurements from the same site, high sensitivity to low levels of oxygen, and non-invasive options. The existing techniques are especially useful for studies in small animals, where the depth of measurements is not an overriding issue. In larger animals and potentially in human subjects, non-invasive techniques seem to be immediately applicable to study phenomena very near the surface (within 10 mm) while invasive techniques have some very promising uses. The clinical uses of EPR oximetry which seem especially promising and likely to be undertaken in the near future are long-term monitoring of the status and response to treatment of peripheral vascular disease and optimizing cancer therapy by enabling it to be modified on the basis of the pO 2 measured in the tumour. (author)

  13. Effect of hypoxia on cerebral blood flow regulation during rest and exercise : role of cerebral oxygen delivery on performance

    OpenAIRE

    Fan, J.-L.

    2014-01-01

    Adequate supply of oxygen to the brain is critical for maintaining normal brain function. Severe hypoxia, such as that experienced during high altitude ascent, presents a unique challenge to brain oxygen (O2) supply. During high-intensity exercise, hyperventilation-induced hypocapnia leads to cerebral vasoconstriction, followed by reductions in cerebral blood flow (CBF), oxygen delivery (DO2), and tissue oxygenation. This reduced O2 supply to the brain could potentially account for the reduce...

  14. Local cerebral blood flow (1CBF) and oxygen consumption (1CMRO2) in evolving irreversible ischemic infarction: a study with positron tomography and oxygen-15

    International Nuclear Information System (INIS)

    Baron, J.C.; Rougemont, D.; Lebrun-Grandie, P.; Comar, D.; Bousser, M.G.; Bories, J.; Castaigne, P.; Cabanis, E.

    1982-09-01

    In 25 patients suffering from cerebral ischemia set up in the area of the internal carotid artery the local cerebral blood flow (lCBF) and local cerebral oxygen consumption (lCMRO 2 ) were measured by the method of continuous inhalation of oxygen 15-labelled gas combined with positron emission tomography. These two local parameters and their ratio, the local oxygen extraction rate (lO 2 E), were studied inside the brain region tending spontaneously towards ischemic necrosis, a zone defined by means of repeated tomodensitometric examinations. The essential facts observed are the variability of the lCBF and the lO 2 E values, from extremely low to extremely high, whereas the collapse of the lCMRO 2 is constant. Consequently this last parameter alone would be a good prognostic index, an lCMRO 2 decrease to a level below about 70% of the controlateral value indicating that the necrosis is spontaneously irreparable. These results are discussed in the light of published data

  15. Observer-based Coal Mill Control using Oxygen Measurements

    DEFF Research Database (Denmark)

    Andersen, Palle; Bendtsen, Jan Dimon; S., Tom

    2006-01-01

    This paper proposes a novel approach to coal flow estimation in pulverized coal mills, which utilizes measurements of oxygen content in the flue gas. Pulverized coal mills are typically not equipped with sensors that detect the amount of coal injected into the furnace. This makes control...... of the coal flow difficult, causing stability problems and limits the plant's load following capabilities. To alleviate this problem without having to rely on expensive flow measurement equipment, a novel observer-based approach is investigated. A Kalman filter based on measurements of combustion air flow led...... into the furnace and oxygen concentration in the flue gas is designed to estimate the actual coal flow injected into the furnace. With this estimate, it becomes possible to close an inner loop around the coal mill itself, thus giving a better disturbance rejection capability. The approach is validated against...

  16. Measuring oxygen uptake in fishes with bimodal respiration.

    Science.gov (United States)

    Lefevre, S; Bayley, M; McKenzie, D J

    2016-01-01

    Respirometry is a robust method for measurement of oxygen uptake as a proxy for metabolic rate in fishes, and how species with bimodal respiration might meet their demands from water v. air has interested researchers for over a century. The challenges of measuring oxygen uptake from both water and air, preferably simultaneously, have been addressed in a variety of ways, which are briefly reviewed. These methods are not well-suited for the long-term measurements necessary to be certain of obtaining undisturbed patterns of respiratory partitioning, for example, to estimate traits such as standard metabolic rate. Such measurements require automated intermittent-closed respirometry that, for bimodal fishes, has only recently been developed. This paper describes two approaches in enough detail to be replicated by the interested researcher. These methods are for static respirometry. Measuring oxygen uptake by bimodal fishes during exercise poses specific challenges, which are described to aid the reader in designing experiments. The respiratory physiology and behaviour of air-breathing fishes is very complex and can easily be influenced by experimental conditions, and some general considerations are listed to facilitate the design of experiments. Air breathing is believed to have evolved in response to aquatic hypoxia and, probably, associated hypercapnia. The review ends by considering what realistic hypercapnia is, how hypercapnic tropical waters can become and how this might influence bimodal animals' gas exchange. © 2015 The Fisheries Society of the British Isles.

  17. Zolpidem reduces the blood oxygen level-dependent signal during visual system stimulation

    OpenAIRE

    Licata, Stephanie C.; Lowen, Steven B.; Trksak, George H.; MacLean, Robert R.; Lukas, Scott E.

    2011-01-01

    Zolpidem is a short-acting imidazopyridine hypnotic that binds at the benzodiazepine binding site on specific GABAA receptors to enhance fast inhibitory neurotransmission. The behavioral and receptor pharmacology of zolpidem has been studied extensively, but little is known about its neuronal substrates in vivo. In the present within-subject, double-blind, and placebo-controlled study, blood oxygen level-dependent functional magnetic resonance imaging (BOLD fMRI) at 3 Tesla was used to assess...

  18. Effect of carbogen on tumor oxygenation: combined fluorine-19 and proton MRI measurements

    International Nuclear Information System (INIS)

    Fan Xiaobing; River, Jonathan N.; Zamora, Marta; Al-Hallaq, Hania A.; Karczmar, Gregory S.

    2002-01-01

    Purpose: Blood oxygen level dependent (BOLD) contrast in magnetic resonance imaging (MRI) has been widely used for noninvasive evaluation of the effects of tumor-oxygenating agents. However, there have been few tests of the validity of this method. The goal of the present work was to use the T 1 of fluorine-19 in perfluorocarbon (PFC) emulsions as a 'gold standard' for comparison with BOLD MRI. Methods and Materials: Rats bearing R3230AC tumors implanted in the hind limb were injected with an emulsion of perfluoro-15-crown-5-ether for 2-3 days before experiments, which ensured that the PFC emulsion concentrated in the tumors. We correlated changes in tumor oxygenation caused by carbogen inhalation measured by 1 H BOLD MRI with quantitative 19 F measurements. The 19 F spin-lattice relaxation rate R 1 (= 1/T 1 ) was measured to determine initial oxygen tension (pO 2 ) in each image pixel containing the PFC, and changes in pO 2 during carbogen (95% O 2 , 5% CO 2 ) breathing. In a second carbogen breathing period, changes in water signal linewidth were measured using high spectral and spatial resolution imaging. 19 F and 1 H measurements were used to classify pixels as responders to carbogen (pixels where oxygen increased significantly) or nonresponders (no significant change in tumor oxygenation). Results: The 19 F and 1 H measurements agreed in 65% ± 11% of pixels (n = 14). Agreement was even stronger among pixels where 1 H showed increased oxygenation; 19 F measurements agreed with 1 H measurements in over 79% ± 11% of these pixels. Similarly, there was strong agreement between the two modalities in pixels where 19 F reported no change in pO 2 ; 1 H also showed no changes in 76% ± 18% of these pixels. Quantitative correlation of changes T 2 * (ΔT 2 *) in 1 H and changes R 1 (ΔR 1 ) in 19 F was weak during carbogen breathing, and averaged over the whole tumor was ∼0.40 for 14 experiments. However, the spatial patterns of 1 H and 19 F changes were qualitatively

  19. Some TPC measurements in an oxygen beam at the AGS

    International Nuclear Information System (INIS)

    Love, W.A.; Etkin, A.; Foley, K.J.; Hackenburg, R.W.; Longacre, R.S.; Morris, T.W.; Platner, E.D.; Saulys, A.C.; Bonner, B.E.; Buchanan, J.A.; Chiou, C.N.; Clement, J.M.; Corcoran, M.D.; Krishna, N.; Kruk, J.W.; Miettinen, H.E.; Mutchler, G.S.; Nessi-Tedaldi, F.; Nessi, M.; Phillips, G.C.; Roberts, J.B.; Chan, C.S.; Kramer, M.A.; Hallman, T.J.; Madansky, L.; Lindenbaum, S.J.

    1989-01-01

    The principal detector for AGS Experiment 810 is a Time Projection Chamber (TPC) in which it is intended to measure momenta and angles of a major fraction of the charged particles from each light ion collision. This report describes the results of a test of a prototype of the TPC in a beam of (14.6x16=233.6 GeV/c) oxygen ions run in June of this year. (orig.)

  20. Acrolein-Induced Increases in Blood Pressure and Heart Rate Are Coupled with Decreased Blood Oxygen Levels During Exposure in Hypertensive Rats

    Science.gov (United States)

    Exposure to air pollution increases the risk of cardiovascular morbidity and mortality, especially in individuals with pre-existing cardiovascular disease. Recent studies link exposure to air pollution with reduced blood oxygen saturation suggesting that hypoxia is a potential me...

  1. First experience with a novel luminescence-based optical sensor for measurement of oxygenation in tumors

    International Nuclear Information System (INIS)

    Jarm, T.; Miklavcic, D.; Lesnicar, H.; Sersa, G.

    2001-01-01

    Background. The purpose of this preliminary study was to evaluate a novel luminescence-based fiber-optic sensor (OxyLite system) for the measurement of partial pressure of oxygen (pO 2 ) in tumors and for the detection of changes in pO 2 as a function of time. The new method was used simultaneously with the laser Doppler flowmetry method for the measurement of relative tissue perfusion. Materials and methods. Blood perfusion and pO 2 were measured continuously via fiber-optic sensors inserted into SA-1 tumors in anesthetized A/J mice. The changes in blood flow and oxygenation of tumors were induced by transient changes of the parameters of anesthesia and by injection of a vasoactive drug hydralazine. Results. Both optical methods used in the study successfully detected the induced changes in blood flow and pO 2 . The measurements of pO 2 were well correlated with measurements of microcirculatory blood perfusion. In the majority of pO 2 measurements, we observed an unexpected behavior of the signal during the stabilization process immediately after the insertion of the probe into tumor. This behaviour of the pO 2 signal was most probably caused by local tissue damage induced by the insertion of the probe. Conclusion. The novel luminescence-based optical oximetry can reliably detect local pO 2 changes in tumors as a function of time but some aspects of prolonged pO 2 measurement by this method require further investigation. (author)

  2. Tissue oxygenation and haemodynamics measurement with spatially resolved NIRS

    Science.gov (United States)

    Zhang, Y.; Scopesi, F.; Serra, G.; Sun, J. W.; Rolfe, P.

    2010-08-01

    We describe the use of Near Infrared Spectroscopy (NIRS) for the non-invasive investigation of changes in haemodynamics and oxygenation of human peripheral tissues. The goal was to measure spatial variations of tissue NIRS oxygenation variables, namely deoxy-haemoglobin (HHb), oxy-haemoglobin (HbO2), total haemoglobin (HbT), and thereby to evaluate the responses of the peripheral circulation to imposed physiological challenges. We present a skinfat- muscle heterogeneous tissue model with varying fat thickness up to 15mm and a Monte Carlo simulation of photon transport within this model. The mean partial path length and the mean photon visit depth in the muscle layer were derived for different source-detector spacing. We constructed NIRS instrumentation comprising of light-emitting diodes (LED) as light sources at four wavelengths, 735nm, 760nm, 810nm and 850nm and sensitive photodiodes (PD) as the detectors. Source-detector spacing was varied to perform measurements at different depths within forearm tissue. Changes in chromophore concentration in response to venous and arterial occlusion were calculated using the modified Lambert-Beer Law. Studies in fat and thin volunteers indicated greater sensitivity in the thinner subjects for the tissue oxygenation measurement in the muscle layer. These results were consistent with those found using Monte Carlo simulation. Overall, the results of this investigation demonstrate the usefulness of the NIRS instrument for deriving spatial information from biological tissues.

  3. Cerebral blood flow and oxygen metabolism in patients with Parkinson's disease

    Energy Technology Data Exchange (ETDEWEB)

    Kitamura, Shin; Ujike, Takashi; Kuroki, Soemu; Sakamoto, Shizuki; Soeda, Toshiyuki; Terashi, Akiro; Iio, Masaaki

    1988-10-01

    The purpose of this study was to determine functional changes in the cerebral cortex and basal ganglia in Parkinson's disease (PD). Cerebral blood flow (CBF), oxygen extraction fraction (OEF), and cerebral metabolic rate of oxygen (CMRO/sub 2/) were determined using 0-15 positron emission tomography in 10 PD patients and five age-matched healthy volunteers. There was a tendency among PD patients towards a decreased CBF and CMRO/sub 2/ in the cerebral cortex and basal ganglia. These values were significantly lower in the frontal cortex in the PD group than the control group. There was no difference in OEF between the groups. A more decreased cerebral oxygen metabolism was observed in patients staged as severer on the scale of Hoehn and Yahr. There was no correlation between cerebral oxygen metabolism and tremor, rigidity, or bradykinesis. A decreased cerebral oxygen metabolism was associated with mental disorders, such as depression, hallucination, and dementia. These results may provide an important clue for the understanding of mesocortical dopaminergic pathway and the relationship between PD and dementia. (N.K.).

  4. Cerebral blood flow and oxygen metabolism in patients with Parkinson's disease

    International Nuclear Information System (INIS)

    Kitamura, Shin; Ujike, Takashi; Kuroki, Soemu; Sakamoto, Shizuki; Soeda, Toshiyuki; Terashi, Akiro; Iio, Masaaki.

    1988-01-01

    The purpose of this study was to determine functional changes in the cerebral cortex and basal ganglia in Parkinson's disease (PD). Cerebral blood flow (CBF), oxygen extraction fraction (OEF), and cerebral metabolic rate of oxygen (CMRO 2 ) were determined using 0-15 positron emission tomography in 10 PD patients and five age-matched healthy volunteers. There was a tendency among PD patients towards a decreased CBF and CMRO 2 in the cerebral cortex and basal ganglia. These values were significantly lower in the frontal cortex in the PD group than the control group. There was no difference in OEF between the groups. A more decreased cerebral oxygen metabolism was observed in patients staged as severer on the scale of Hoehn and Yahr. There was no correlation between cerebral oxygen metabolism and tremor, rigidity, or bradykinesis. A decreased cerebral oxygen metabolism was associated with mental disorders, such as depression, hallucination, and dementia. These results may provide an important clue for the understanding of mesocortical dopaminergic pathway and the relationship between PD and dementia. (N.K.)

  5. [Effect of hemodilution with 10% hydroxyethyl starch solution (MW 200,000/9.5) on the flow properties of blood, arterial blood gases and conjunctival oxygen partial pressure in patients with cerebral infarct].

    Science.gov (United States)

    Staedt, U; Hütt, M; Herrmann, B; Seufzer, U; Leweling, H

    1989-06-01

    Hemorheological parameters, arterial blood gases and conjunctival oxygen tension were measured in 15 patients with acute ischemic stroke and compared with values obtained in an age matched reference group. Since the conjunctival capillary bed is perfused by the ophthalmic artery, it reflects the oxygen delivery to the areas supplied by the internal carotid artery. Measurements of conjunctival oxygen tension are simple and safe. Patients with acute ischemic stroke showed a lowered conjunctival oxygen tension; this holds true especially to the ipsilateral side, i.e. the side where the attack occurred, and to a lesser extent to the other side. By contrast, the ratio of arterial/conjunctival pO2 was disturbed only on the ipsilateral side. Furthermore, these patients had pathologically elevated values for red cell aggregation, whole blood and plasma viscosity. After infusing 500 ml 10% middle-molecular-weight hydroxyethyl starch (10% HAES-steril) and phlebotomy (250 ml) blood fluidity was normalized, although the hematokrit was only slightly reduced. Arterial pO2 improved slightly while pCO2 remained unchanged. Conjunctival oxygen tension improved by 30% on the ipsilateral and by 10% on the contralateral side, the ipsilateral values always remaining significantly lower. The ratio conjunctival/arterial pO2 raised only on the ipsilateral side where it was below the reference range before hemodilution. In addition to the well known improvement of blood fluidity and augmentation of cerebral blood flow following hemodilution in patients with acute ischemic stroke, there seems to be an increase in oxygen supply in the territories of both internal carotid arteries, especially on the ipsilateral side as indicated by the values of conjunctival oxygen tension and the ratio of conjunctival to arterial pO2.

  6. Vascular Steal Explains Early Paradoxical Blood Oxygen Level-Dependent Cerebrovascular Response in Brain Regions with Delayed Arterial Transit Times

    Directory of Open Access Journals (Sweden)

    Julien Poublanc

    2013-04-01

    Full Text Available Introduction: Blood oxygen level-dependent (BOLD magnetic resonance imaging (MRI during manipulation of inhaled carbon dioxide (CO2 can be used to measure cerebrovascular reactivity (CVR and map regions of exhausted cerebrovascular reserve. These regions exhibit a reduced or negative BOLD response to inhaled CO2. In this study, we sought to clarify the mechanism behind the negative BOLD response by investigating its time delay (TD. Dynamic susceptibility contrast (DSC MRI with the injection of a contrast agent was used as the gold standard in order to provide measurement of the blood arrival time to which CVR TD could be compared. We hypothesize that if negative BOLD responses are the result of a steal phenomenon, they should be synchronized with positive BOLD responses from healthy brain tissue, even though the blood arrival time would be delayed. Methods: On a 3-tesla MRI system, BOLD CVR and DSC images were collected in a group of 19 patients with steno-occlusive cerebrovascular disease. For each patient, we generated a CVR magnitude map by regressing the BOLD signal with the end-tidal partial pressure of CO2 (PETCO2, and a CVR TD map by extracting the time of maximum cross-correlation between the BOLD signal and PETCO2. In addition, a blood arrival time map was generated by fitting the DSC signal with a gamma variate function. ROI masks corresponding to varying degrees of reactivity were constructed. Within these masks, the mean CVR magnitude, CVR TD and DSC blood arrival time were extracted and averaged over the 19 patients. CVR magnitude and CVR TD were then plotted against DSC blood arrival time. Results: The results show that CVR magnitude is highly correlated to DSC blood arrival time. As expected, the most compromised tissues with the longest blood arrival time have the lowest (most negative CVR magnitude. However, CVR TD shows a noncontinuous relationship with DSC blood arrival time. CVR TD is well correlated to DSC blood arrival time

  7. Blood and dried blood spot telomere length measurement by qPCR: assay considerations.

    Directory of Open Access Journals (Sweden)

    DeAnna L Zanet

    Full Text Available Measurement of telomere length is crucial for the study of telomere maintenance and its role in molecular pathophysiology of diseases and in aging. Several methods are used to measure telomere length, the choice of which usually depends on the type and size of sample to be assayed, as well as cost and throughput considerations. The goal of this study was to investigate the factors that may influence the reliability of qPCR-based relative telomere length measurements in whole blood. Day to day intra-individual variability, types of blood anticoagulant, sample storage conditions, processing and site of blood draw were investigated. Two qPCR-based methods to measure telomere length (monoplex vs. multiplex were also investigated and showed a strong correlation between them. Freezing and thawing of the blood and storage of the blood at 4°C for up to 4 days did not affect telomere length values. Telomere lengths in dried blood spots were significantly higher than both whole blood and peripheral mononuclear blood cells, and were highly correlated with both. We found that telomere length measurements were significantly higher in dried blood spots collected directly from fingertip prick compared to dried blood spots prepared with anticoagulated whole blood collected from the finger, and non-blotted whole blood taken from both finger and arm venipuncture. This suggests that DNA from cells blotted on paper is not equivalent to that collected from venipuncture whole blood, and caution should be taken when comparing between blood sample types.

  8. Value of cerebral blood flow rate and regional oxygen consumption studies in cerebral ischaemia

    Energy Technology Data Exchange (ETDEWEB)

    Clanet, M

    1987-06-18

    Studies of experimentally-induced ischaemia have shown that the intensity of neuronal suffering is related to the fall in perfusion rate. Below a certain level, called functional threshold, cerebral function is reversibly altered, whereas at a lower level (tissue necrosis threshold) the damage inflicted on neurons is irreversible. Between these two thresholds lies a ''penumbra zone''. This concept of thresholds must be mitigated by 2 parameters: duration of ischaemia and selective vulnerability of the various structures affected. Variations in blood flow rate only indirectly affect the state of tissues. Techniques developed from positron emission tomography make it possible to evaluate the metabolic activity of brain tissue in vivo: oxygen consumption (CMRO/sub 2/), oxygen extraction (EO/sub 2/) and glucose consumption (CMRG) which are thus correlated to cerebral blood flow and cerebral blood volume, sometimes also to tissue pH. Normal relations between blood flow rate and metabolism may be altered. Misery perfusion reflects a fall in cerebral blood flow with an increase in EO/sub 2/ and often a decrease in CMRO/sub 2/, whereas luxury perfusion reflects an increase in cerebral blood flow rate with reduction of CMRO/sub 2/, EO/sub 2/ and CMRG. The type of alteration encountered in human ischaemia varies according to the nature of the accident: studies of transient accidents emphasize the different haemodynamic aspects of occlusion of the wider arteries. The metabolic and haemodynamic profiles of established ischaemic accidents vary according to their type and to the time of the study, reflecting the complexity of the physiopathological mechanisms involved; they are frequently associated with metabolic repercussions at a distance from the ischaemic focus, which supports the concept of diaschisis.

  9. Value of cerebral blood flow rate and regional oxygen consumption studies in cerebral ischaemia

    International Nuclear Information System (INIS)

    Clanet, M.

    1987-01-01

    Studies of experimentally-induced ischaemia have shown that the intensity of neuronal suffering is related to the fall in perfusion rate. Below a certain level, called functional threshold, cerebral function is reversibly altered, whereas at a lower level (tissue necrosis threshold) the damage inflicted on neurons is irreversible. Between these two thresholds lies a ''penumbra zone''. This concept of thresholds must be mitigated by 2 parameters: duration of ischaemia and selective vulnerability of the various structures affected. Variations in blood flow rate only indirectly affect the state of tissues. Techniques developed from positron emission tomography make it possible to evaluate the metabolic activity of brain tissue in vivo: oxygen consumption (CMRO 2 ), oxygen extraction (EO 2 ) and glucose consumption (CMRG) which are thus correlated to cerebral blood flow and cerebral blood volume, sometimes also to tissue pH. Normal relations between blood flow rate and metabolism may be altered. Misery perfusion reflects a fall in cerebral blood flow with an increase in EO 2 and often a decrease in CMRO 2 , whereas luxury perfusion reflects an increase in cerebral blood flow rate with reduction of CMRO 2 , EO 2 and CMRG. The type of alteration encountered in human ischaemia varies according to the nature of the accident: studies of transient accidents emphasize the different haemodynamic aspects of occlusion of the wider arteries. The metabolic and haemodynamic profiles of established ischaemic accidents vary according to their type and to the time of the study, reflecting the complexity of the physiopathological mechanisms involved; they are frequently associated with metabolic repercussions at a distance from the ischaemic focus, which supports the concept of diaschisis [fr

  10. Blood Pressure Measurement: Clinic, Home, Ambulatory, and Beyond

    Science.gov (United States)

    Drawz, Paul E.; Abdalla, Mohamed; Rahman, Mahboob

    2014-01-01

    Blood pressure has traditionally been measured in the clinic setting using the auscultory method and a mercury sphygmomanometer. Technological advances have led to improvements in measuring clinic blood pressure and allowed for measuring blood pressures outside the clinic. This review outlines various methods for evaluating blood pressure and the clinical utility of each type of measurement. Home blood pressures and 24 hour ambulatory blood pressures have improved our ability to evaluate risk for target organ damage and hypertension related morbidity and mortality. Measuring home blood pressures may lead to more active participation in health care by patients and has the potential to improve blood pressure control. Ambulatory blood pressure monitoring enables the measuring nighttime blood pressures and diurnal changes, which may be the most accurate predictors of risk associated with elevated blood pressure. Additionally, reducing nighttime blood pressure is feasible and may be an important component of effective antihypertensive therapy. Finally, estimating central aortic pressures and pulse wave velocity are two of the newer methods for assessing blood pressure and hypertension related target organ damage. PMID:22521624

  11. Signal quality measures for unsupervised blood pressure measurement

    International Nuclear Information System (INIS)

    Abdul Sukor, J; Redmond, S J; Lovell, N H; Chan, G S H

    2012-01-01

    Accurate systolic and diastolic pressure estimation, using automated blood pressure measurement, is difficult to achieve when the transduced signals are contaminated with noise or interference, such as movement artifact. This study presents an algorithm for automated signal quality assessment in blood pressure measurement by determining the feasibility of accurately detecting systolic and diastolic pressures when corrupted with various levels of movement artifact. The performance of the proposed algorithm is compared to a manually annotated reference scoring (RS). Based on visual representations and audible playback of Korotkoff sounds, the creation of the RS involved two experts identifying sections of the recorded sounds and annotating sections of noise contamination. The experts determined the systolic and diastolic pressure in 100 recorded Korotkoff sound recordings, using a simultaneous electrocardiograph as a reference signal. The recorded Korotkoff sounds were acquired from 25 healthy subjects (16 men and 9 women) with a total of four measurements per subject. Two of these measurements contained purposely induced noise artifact caused by subject movement. Morphological changes in the cuff pressure signal and the width of the Korotkoff pulse were extracted features which were believed to be correlated with the noise presence in the recorded Korotkoff sounds. Verification of reliable Korotkoff pulses was also performed using extracted features from the oscillometric waveform as recorded from the inflatable cuff. The time between an identified noise section and a verified Korotkoff pulse was the key feature used to determine the validity of possible systolic and diastolic pressures in noise contaminated Korotkoff sounds. The performance of the algorithm was assessed based on the ability to: verify if a signal was contaminated with any noise; the accuracy, sensitivity and specificity of this noise classification, and the systolic and diastolic pressure

  12. 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; Koeners, Maarten P

    2016-11-01

    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. 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 . Equi-pressor infusion of

  13. 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

  14. High-affinity hemoglobin and blood oxygen saturation in diving emperor penguins.

    Science.gov (United States)

    Meir, Jessica U; Ponganis, Paul J

    2009-10-01

    The emperor penguin (Aptenodytes forsteri) thrives in the Antarctic underwater environment, diving to depths greater than 500 m and for durations longer than 23 min. To examine mechanisms underlying the exceptional diving ability of this species and further describe blood oxygen (O2) transport and depletion while diving, we characterized the O2-hemoglobin (Hb) dissociation curve of the emperor penguin in whole blood. This allowed us to (1) investigate the biochemical adaptation of Hb in this species, and (2) address blood O2 depletion during diving, by applying the dissociation curve to previously collected partial pressure of O2 (PO2) profiles to estimate in vivo Hb saturation (SO2) changes during dives. This investigation revealed enhanced Hb-O2 affinity (P50=28 mmHg, pH 7.5) in the emperor penguin, similar to high-altitude birds and other penguin species. This allows for increased O2 at low blood PO2 levels during diving and more complete depletion of the respiratory O2 store. SO2 profiles during diving demonstrated that arterial SO2 levels are maintained near 100% throughout much of the dive, not decreasing significantly until the final ascent phase. End-of-dive venous SO2 values were widely distributed and optimization of the venous blood O2 store resulted from arterialization and near complete depletion of venous blood O2 during longer dives. The estimated contribution of the blood O2 store to diving metabolic rate was low and highly variable. This pattern is due, in part, to the influx of O2 from the lungs into the blood during diving, and variable rates of tissue O2 uptake.

  15. Blood oxygen depletion is independent of dive function in a deep diving vertebrate, the northern elephant seal.

    Directory of Open Access Journals (Sweden)

    Jessica U Meir

    Full Text Available Although energetics is fundamental to animal ecology, traditional methods of determining metabolic rate are neither direct nor instantaneous. Recently, continuous blood oxygen (O2 measurements were used to assess energy expenditure in diving elephant seals (Mirounga angustirostris, demonstrating that an exceptional hypoxemic tolerance and exquisite management of blood O2 stores underlie the extraordinary diving capability of this consummate diver. As the detailed relationship of energy expenditure and dive behavior remains unknown, we integrated behavior, ecology, and physiology to characterize the costs of different types of dives of elephant seals. Elephant seal dive profiles were analyzed and O2 utilization was classified according to dive type (overall function of dive: transit, foraging, food processing/rest. This is the first account linking behavior at this level with in vivo blood O2 measurements in an animal freely diving at sea, allowing us to assess patterns of O2 utilization and energy expenditure between various behaviors and activities in an animal in the wild. In routine dives of elephant seals, the blood O2 store was significantly depleted to a similar range irrespective of dive function, suggesting that all dive types have equal costs in terms of blood O2 depletion. Here, we present the first physiological evidence that all dive types have similarly high blood O2 demands, supporting an energy balance strategy achieved by devoting one major task to a given dive, thereby separating dive functions into distinct dive types. This strategy may optimize O2 store utilization and recovery, consequently maximizing time underwater and allowing these animals to take full advantage of their underwater resources. This approach may be important to optimizing energy expenditure throughout a dive bout or at-sea foraging trip and is well suited to the lifestyle of an elephant seal, which spends > 90% of its time at sea submerged making diving its

  16. Using BOLD imaging to measure renal oxygenation dynamics in rats injected with diuretics

    International Nuclear Information System (INIS)

    Kusakabe, Yoshinori; Matsushita, Taro; Honda, Saori; Okada, Sakie; Murase, Kenya

    2010-01-01

    We used blood oxygenation level-dependent magnetic resonance imaging (BOLD MRI) to measure renal oxygenation dynamics in rats injected with diuretics and evaluated diuretic effect on renal oxygenation. We performed BOLD MRI studies in 32 rats using a 1.5-tesla MR imaging system for animal experiments. We intravenously injected rats with saline (n=7), furosemide (n=7), acetazolamide (n=6), or mannitol (n=6). For controls, 6 rats were not injected with drugs. We estimated the apparent transverse relaxation rate (R 2 *) from the apparent transverse relaxation time (T 2 *)-weighted images and measured the time course of R 2 * at 4-min intervals over approximately 30 min. Compared with preadministration values, the R 2 * value did not change significantly in either the cortex or medulla in the control and mannitol groups but decreased significantly in the saline group; the R 2 * value significantly decreased in the medulla but did not change significantly in the cortex in the furosemide group; and the R 2 * value significantly increased in the medulla and significantly decreased in the cortex in the acetazolamide group. Our study results suggest that BOLD MRI is useful for evaluating the dynamics of renal oxygenation in response to various diuretics in the renal cortex and in the medulla. (author)

  17. The effects of arterial carbon dioxide partial pressure and sevoflurane on capillary venous cerebral blood flow and oxygen saturation during craniotomy.

    Science.gov (United States)

    Klein, Klaus Ulrich; Glaser, Martin; Reisch, Robert; Tresch, Achim; Werner, Christian; Engelhard, Kristin

    2009-07-01

    Intraoperative routine monitoring of cerebral blood flow and oxygenation remains a technological challenge. Using the physiological principle of carbon dioxide reactivity of cerebral vasculature, we investigated a recently developed neuromonitoring device (oxygen-to-see, O2C device) for simultaneous measurements of regional cerebral blood flow (rvCBF), blood flow velocity (rvVelo), oxygen saturation (srvO2), and hemoglobin amount (rvHb) at the capillary venous level in patients subjected to craniotomy. Twenty-six neurosurgical patients were randomly assigned to anesthesia with 1.4% or 2.0% sevoflurane end-tidal concentration. After craniotomy, a fiberoptic probe was applied on a macroscopically healthy surface of cerebral tissue next to the site of surgery. Simultaneous measurements in 2 and 8 mm cerebral depth were performed in each patient during lower (35 mm Hg) and higher (45 mm Hg) levels (random order) of arterial carbon dioxide partial pressure (PaCO2). The principle of these measurements relies on the combination of laser-Doppler flowmetry (rvCBF, rvVelo) and photo-spectrometry (srvO2, rvHb). Linear models were fitted to test changes of end points (rvCBF, rvVelo, srvO2, rvHb) in response to lower and higher levels of PaCO2, 1.4% and 2.0% sevoflurane end-tidal concentration, and 2 and 8 mm cerebral depth. RvCBF and rvVelo were elevated by PaCO2 independent of sevoflurane concentration in 2 and 8 mm depth of cerebral tissue (P oxygen was decreased by elevated PaCO2. Unchanged levels of rvHb signify that there was no blood loss during measurements. Data suggest that the device allows detection of local changes in blood flow and oxygen saturation in response to different PaCO2 levels in predominant venous cerebral microvessels.

  18. Auscultatory versus oscillometric measurement of blood pressure in octogenarians

    DEFF Research Database (Denmark)

    Rosholm, Jens-Ulrik; Pedersen, Sidsel Arnspang; Matzen, Lars

    2012-01-01

    Auscultatory measurement using a sphygmomanometer has been the predominant method for clinical estimation of blood pressure, but it is now rapidly being replaced by oscillometric measurement.......Auscultatory measurement using a sphygmomanometer has been the predominant method for clinical estimation of blood pressure, but it is now rapidly being replaced by oscillometric measurement....

  19. Theoretical model for optical oximetry at the capillary level: exploring hemoglobin oxygen saturation through backscattering of single red blood cells

    Science.gov (United States)

    Liu, Rongrong; Spicer, Graham; Chen, Siyu; Zhang, Hao F.; Yi, Ji; Backman, Vadim

    2017-02-01

    Oxygen saturation (sO2) of red blood cells (RBCs) in capillaries can indirectly assess local tissue oxygenation and metabolic function. For example, the altered retinal oxygenation in diabetic retinopathy and local hypoxia during tumor development in cancer are reflected by abnormal sO2 of local capillary networks. However, it is far from clear whether accurate label-free optical oximetry (i.e., measuring hemoglobin sO2) is feasible from dispersed RBCs at the single capillary level. The sO2-dependent hemoglobin absorption contrast present in optical scattering signal is complicated by geometry-dependent scattering from RBCs. We present a numerical study of backscattering spectra from single RBCs based on the first-order Born approximation, considering practical factors: RBC orientations, size variation, and deformations. We show that the oscillatory spectral behavior of RBC geometries is smoothed by variations in cell size and orientation, resulting in clear sO2-dependent spectral contrast. In addition, this spectral contrast persists with different mean cellular hemoglobin content and different deformations of RBCs. This study shows for the first time the feasibility of, and provides a theoretical model for, label-free optical oximetry at the single capillary level using backscattering-based imaging modalities, challenging the popular view that such measurements are impossible at the single capillary level.

  20. Comparison of extracapillary and endocapillary blood flow oxygenators for open heart surgery in dogs: efficiency of gas exchange and platelet conservation.

    Science.gov (United States)

    Hoshi, Katsuichiro; Tanaka, Ryou; Shibazaki, Akira; Nagashima, Yukiko; Hirao, Hidehiro; Namiki, Ryosuke; Takashima, Kazuaki; Noishiki, Yasuharu; Yamane, Yoshihisa

    2003-03-01

    The goal of the current study was to compare the efficiency of gas exchange and platelet conservation of a new extracapillary blood flow oxygenator versus an endocapillary blood flow oxygenator during open heart surgery with extracorporeal circulation in dogs. Dilation and remodeling of the right ventricular outflow tract of dogs was performed using a patch graft technique to simulate pulmonary stenosis. Sequential pre- and post-operative blood analysis revealed that gas exchange efficiency and platelet conservation was significantly greater with the extracapillary blood flow oxygenator than with the endocapillary blood flow oxygenator. However, the priming volume of the extracapillary blood flow oxygenator was significantly greater, leading to hemodilution. We conclude that while the extracapillary blood flow oxygenator provided benefits in terms of gas exchange and platelet conservation, development of a smaller extracapillary blood flow type oxygenator to reduce hemodilution effects would be beneficial.

  1. Comparison of oxygen saturation values and measurement times by pulse oximetry in various parts of the body.

    Science.gov (United States)

    Yönt, Gülendam Hakverdioğlu; Korhan, Esra Akin; Khorshid, Leyla

    2011-11-01

    The aim of this study, which included 40 patients, was to compare the values pulse oximetry and the measurement times in various regions of the body. Data were analyzed using intraclass correlation coefficient test and paired-sample test. The confidence power value was found to be .81 for the comparison of oxygen saturation values by arterial blood gas analysis and measurement by the forehead probe. It was found that the time for oxygen saturation measurement using the forehead probe was shorter than those using the finger and toe probes. Copyright © 2011 Elsevier Inc. All rights reserved.

  2. Ion measurements in premixed methane-oxygen flames

    KAUST Repository

    Alquaity, Awad

    2014-07-25

    Ions are formed as a result of chemi-ionization processes in combustion systems. Recently, there has been an increasing interest in understanding flame ion chemistry due to the possible application of external electric fields to reduce emissions and improve combustion efficiency by active control of combustion process. In order to predict the effect of external electric fields on combustion plasma, it is critical to gain a good understanding of the flame ion chemistry. In this work, a Molecular Beam Mass Spectrometer (MBMS) is utilized to measure ion concentration profiles in premixed methane-oxygen-argon burner-stabilized flames. Lean, stoichiometric and rich flames at atmospheric pressure are used to study the dependence of ion chemistry on equivalence ratio of premixed flames. The relative ion concentration profiles are compared qualitatively with previous methane-oxygen studies and show good agreement. The relative ion concentration data obtained in the present study can be used to validate and improve ion chemistry models for methane-oxygen flames.

  3. Impaired Muscle Oxygenation and Elevated Exercise Blood Pressure in Hypertensive Patients: Links With Vascular Stiffness.

    Science.gov (United States)

    Dipla, Konstantina; Triantafyllou, Areti; Koletsos, Nikolaos; Papadopoulos, Stavros; Sachpekidis, Vasileios; Vrabas, Ioannis S; Gkaliagkousi, Eugenia; Zafeiridis, Andreas; Douma, Stella

    2017-08-01

    This study examined in vivo (1) skeletal muscle oxygenation and microvascular function, at rest and during handgrip exercise, and (2) their association with macrovascular function and exercise blood pressure (BP), in newly diagnosed, never-treated patients with hypertension and normotensive individuals. Ninety-one individuals (51 hypertensives and 40 normotensives) underwent office and 24-hour ambulatory BP, arterial stiffness, and central aortic BP assessment, followed by a 5-minute arterial occlusion and a 3-minute submaximal handgrip exercise. Changes in muscle oxygenated and deoxygenated hemoglobin and tissue oxygen saturation were continuously monitored by near-infrared spectroscopy and beat-by-beat BP by Finapres. Hypertensives had higher ( P age and body mass index (BMI) adjusted). When exercising at the same submaximal intensity, hypertensives required a significantly greater ( P hypertension exhibit prominent reductions in in vivo indices of skeletal muscle oxidative capacity, suggestive of mitochondrial dysfunction, and blunted muscle microvascular reactivity. These dysfunctions were associated with higher aortic systolic BP and arterial stiffness. Dysregulations in muscle oxygen delivery/utilization and microvascular stiffness, in hypertensive patients, partially contribute to their exaggerated BP during exercise. © 2017 American Heart Association, Inc.

  4. Local cerebral blood flow and local oxygen consumption in prolonged hemiplegic migraine

    International Nuclear Information System (INIS)

    Baron, J.C.; Lebrun-Grandie, P.; Serdaru, M.; Bousser, M.G.; Lhermitte, F.; Cabanis, E.

    1982-09-01

    This work gives the results of a study by positron emission tomography of the cerebral blood flow (CBF), oxygen-extraction rate (O 2 E) and oxygen consumption (CMRO 2 ) during severe and prolonged attack of hemiplegic migraine. The salient facts observed are a high (CBF) in the brain hemisphere affected (ruling out the hypothesis of a persistent cerebral ischemia), together with a collapsed O 2 E (''luxury perfusion'') and especially preservation of the CMRO 2 suggesting a decoupling not only between CBF and CMRO 2 but also between CMRO 2 and functional state of the tissue. Some time after the attack a new study showed the recoupling between CBF and CMRO 2 , but with the latter reduced in the affected hemisphere although the clinical and tomodensitometric state had returned to normal. These new observations should not however be improperly generalised to all migraines, given the unusual characteristics of the disorder in our patient [fr

  5. Changes in hemoglobin-oxygen affinity with shape variations of red blood cells

    Science.gov (United States)

    Chowdhury, Aniket; Dasgupta, Raktim; Majumder, Shovan K.

    2017-10-01

    Shape variations of red blood cells (RBCs) are known to occur upon exposure to various drugs or under diseased conditions. The commonly observed discocytic RBCs can be transformed to echinocytic or stomatocytic shape under such conditions. Raman spectra of the three major shape variations, namely discocyte, echinocyte, and stomatocyte, of RBCs were studied while subjecting the cells to oxygenated and deoxygenated conditions. Analysis of the recorded spectra suggests an increased level of hemoglobin (Hb)-oxygen affinity for the echinocytes. Also, some level of Hb degradation could be noticed for the deoxygenated echinocytes. The effects may arise from a reduced level of intracellular adenosine triphosphate in echinocytic cells and an increased fraction of submembrane Hb.

  6. Impaired cerebral blood flow and oxygenation during exercise in type 2 diabetic patients

    DEFF Research Database (Denmark)

    Kim, Yu-Sok; Seifert, Thomas; Brassard, Patrice

    2015-01-01

    Endothelial vascular function and capacity to increase cardiac output during exercise are impaired in patients with type 2 diabetes (T2DM). We tested the hypothesis that the increase in cerebral blood flow (CBF) during exercise is also blunted and, therefore, that cerebral oxygenation becomes...... affected and perceived exertion increased in T2DM patients. We quantified cerebrovascular besides systemic hemodynamic responses to incremental ergometer cycling exercise in eight male T2DM and seven control subjects. CBF was assessed from the Fick equation and by transcranial Doppler-determined middle...... at higher workloads in T2DM patients and their work capacity and increase in cardiac output were only ~80% of that established in the control subjects. CBF and cerebral oxygenation were reduced during exercise in T2DM patients (P

  7. Observer-Based Fuel Control Using Oxygen Measurement

    DEFF Research Database (Denmark)

    Andersen, Palle; Bendtsen, Jan Dimon; Mortensen, Jan Henrik

    is constructed and validated against data obtained at the plant. A Kalman filter based on measurements of combustion air flow led into the furnace and oxygen concentration in the flue gas is designed to estimate the actual coal flow. With this estimate, it becomes possible to close an inner loop around the coal......This report describes an attempt to improve the existing control af coal mills used at the Danish power plant Nordjyllandsværket Unit 3. The coal mills are not equipped with coal flow sensors; thus an observer-based approach is investigated. A nonlinear differential equation model of the boiler...

  8. Elevated global cerebral blood flow, oxygen extraction fraction and unchanged metabolic rate of oxygen in young adults with end-stage renal disease: an MRI study.

    Science.gov (United States)

    Zheng, Gang; Wen, Jiqiu; Lu, Hanzhang; Lou, Yaxian; Pan, Zhiying; Liu, Wei; Liu, Hui; Li, Xue; Zhang, Zhe; Chen, Huijuan; Kong, Xiang; Luo, Song; Jiang, Xiaolu; Liu, Ya; Zhang, Zongjun; Zhang, Long Jiang; Lu, Guang Ming

    2016-06-01

    To noninvasively assess global cerebral blood flow (CBF), oxygen extraction fraction (OEF) and cerebral metabolic rate of oxygen (CMRO2) in young adults with end-stage renal disease (ESRD). Thirty-six patients and 38 healthy volunteers were included and took part in MR examinations, blood and neuropsychological tests. CBF and OEF were measured by phase-contrast and T2-relaxation-under-spin-tagging MRI techniques, respectively. CMRO2 was computed from CBF, OEF and hematocrit according to Fick's principle. Correlations were performed between MR measurements, blood biochemistry measurements and neuropsychological test scores. Compared with controls, ESRD patients had elevated CBF (72.9 ± 12.5 vs. 63.8 ± 8.5 ml min(-1) 100 g(-1), P < 0.001), elevated OEF (47.2 ± 10.2 vs. 35.8 ± 5.4 %, P < 0.001), but unaffected CMRO2 (199.5 ± 36.4 vs. 193.8 ± 28.6 μmol O2 min(-1) 100 g(-1), P = 0.879). Hematocrit negatively correlated with CBF (r = -0.640, P < 0.001) and OEF (r = -0.701, P < 0.001), but not with CMRO2. Altered neuropsychological test scores of ESRD patients were associated with OEF and CBF, but not with CMRO2. There were weak relationships between eGFR and hematocrit (r = 0.308, P = 0.068) or CBF (r = 0.318, P = 0.059). Our findings suggested that anaemic young adults with ESRD may afford higher CBF and OEF to maintain a normal CMRO2. Despite this compensatory process, however, cognitive function was still impaired and its severity was correlated with their CBF and OEF abnormality. • Anaemic young adults with ESRD may afford higher CBF and OEF. • Anaemic young adults with ESRD maintain a normal CMRO 2 . • Cognitive function was still impaired in young ESRD adults. • The severity of cognitive dysfunction correlated with CBF and OEF changes.

  9. Amperometric micro pH measurements in oxygenated saliva.

    Science.gov (United States)

    Chaisiwamongkhol, Korbua; Batchelor-McAuley, Christopher; Compton, Richard G

    2017-07-24

    An amperometric micro pH sensor has been developed based on the chemical oxidation of carbon fibre surfaces (diameter of 9 μm and length of ca. 1 mm) to enhance the population of surface quinone groups for the measurement of salivary pH. The pH analysis utilises the electrochemically reversible two-electron, two-proton behaviour of surface quinone groups on the micro-wire electrodes. A Nernstian response is observed across the pH range 2-8 which is the pH range of many biological fluids. We highlight the measurement of pH in small volumes of biological fluids without the need for oxygen removal and specifically the micro pH electrode is examined by measuring the pH of commercial synthetic saliva and authentic human saliva samples. The results correspond well with those obtained by using commercial glass pH electrodes on large volume samples.

  10. Arterial Spin Labeling and Blood Oxygen Level-Dependent MRI Cerebrovascular Reactivity in Cerebrovascular Disease

    DEFF Research Database (Denmark)

    Smeeing, Diederik P J; Hendrikse, Jeroen; Petersen, Esben T

    2016-01-01

    BACKGROUND: The cerebrovascular reactivity (CVR) results of blood oxygen level-dependent (BOLD) and arterial spin labeling (ASL) MRI studies performed in patients with cerebrovascular disease (steno-occlusive vascular disease or stroke) were systematically reviewed. SUMMARY: Thirty-one articles...... found a significant lower ASL CVR in the ipsilateral hemispheres of patients compared to controls. KEY MESSAGES: This review brings support for a reduced BOLD and ASL CVR in the ipsilateral hemisphere of patients with cerebrovascular disease. We suggest that future studies will be performed in a uniform...... way so reference values can be established and could be used to guide treatment decisions in patients with cerebrovascular disease....

  11. Effects of levosimendan on glomerular filtration rate, renal blood flow, and renal oxygenation after cardiac surgery with cardiopulmonary bypass: a randomized placebo-controlled study.

    Science.gov (United States)

    Bragadottir, Gudrun; Redfors, Bengt; Ricksten, Sven-Erik

    2013-10-01

    Acute kidney injury develops in a large proportion of patients after cardiac surgery because of the low cardiac output syndrome. The inodilator levosimendan increases cardiac output after cardiac surgery with cardiopulmonary bypass, but a detailed analysis of its effects on renal perfusion, glomerular filtration, and renal oxygenation in this group of patients is lacking. We therefore evaluated the effects of levosimendan on renal blood flow, glomerular filtration rate, renal oxygen consumption, and renal oxygen demand/supply relationship, i.e., renal oxygen extraction, early after cardiac surgery with cardiopulmonary bypass. Prospective, placebo-controlled, and randomized trial. Cardiothoracic ICU of a tertiary center. Postcardiac surgery patients (n=30). The patients were randomized to receive levosimendan, 0.1 µg/kg/min after a loading dose of 12 µg/kg (n=15), or placebo (n=15). The experimental procedure started 4-6 hours after surgery in the ICU during propofol sedation and mechanical ventilation. Systemic hemodynamic were evaluated by a pulmonary artery thermodilution catheter. Renal blood flow and glomerular filtration rate were measured by the renal vein retrograde thermodilution technique and by renal extraction of Cr-EDTA, respectively. Central venous pressure was kept constant by colloid/crystalloid infusion. Compared to placebo, levosimendan increased cardiac index (22%), stroke volume index (15%), and heart rate (7%) and decreased systemic vascular resistance index (21%), whereas mean arterial pressure was not affected. Levosimendan induced significant increases in renal blood flow (12%, prenal vascular resistance (18%, prenal oxygen consumption, or renal oxygen extraction, compared to placebo. After cardiac surgery with cardiopulmonary bypass, levosimendan induces a vasodilation, preferentially of preglomerular resistance vessels, increasing both renal blood flow and glomerular filtration rate without jeopardizing renal oxygenation. Due to its

  12. Three-dimensional multispectral optoacoustic mesoscopy reveals melanin and blood oxygenation in human skin in vivo.

    Science.gov (United States)

    Schwarz, Mathias; Buehler, Andreas; Aguirre, Juan; Ntziachristos, Vasilis

    2016-01-01

    Optical imaging plays a major role in disease detection in dermatology. However, current optical methods are limited by lack of three-dimensional detection of pathophysiological parameters within skin. It was recently shown that single-wavelength optoacoustic (photoacoustic) mesoscopy resolves skin morphology, i.e. melanin and blood vessels within epidermis and dermis. In this work we employed illumination at multiple wavelengths for enabling three-dimensional multispectral optoacoustic mesoscopy (MSOM) of natural chromophores in human skin in vivo operating at 15-125 MHz. We employ a per-pulse tunable laser to inherently co-register spectral datasets, and reveal previously undisclosed insights of melanin, and blood oxygenation in human skin. We further reveal broadband absorption spectra of specific skin compartments. We discuss the potential of MSOM for label-free visualization of physiological biomarkers in skin in vivo. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Effects of race and sex on cerebral hemodynamics, oxygen delivery and blood flow distribution in response to high altitude

    Science.gov (United States)

    Liu, Jie; Liu, Yang; Ren, Li-Hua; Li, Li; Wang, Zhen; Liu, Shan-Shan; Li, Su-Zhi; Cao, Tie-Sheng

    2016-08-01

    To assess racial, sexual, and regional differences in cerebral hemodynamic response to high altitude (HA, 3658 m). We performed cross-sectional comparisons on total cerebral blood flow (TCBF = sum of bilateral internal carotid and vertebral arterial blood flows = QICA + QVA), total cerebrovascular resistance (TCVR), total cerebral oxygen delivery (TCOD) and QVA/TCBF (%), among six groups of young healthy subjects: Tibetans (2-year staying) and Han (Han Chinese) at sea level, Han (2-day, 1-year and 5-year) and Tibetans at HA. Bilateral ICA and VA diameters and flow velocities were derived from duplex ultrasonography; and simultaneous measurements of arterial pressure, oxygen saturation, and hemoglobin concentration were conducted. Neither acute (2-day) nor chronic (>1 year) responses showed sex differences in Han, except that women showed lower TCOD compared with men. Tibetans and Han exhibited different chronic responses (percentage alteration relative to the sea-level counterpart value) in TCBF (-17% vs. 0%), TCVR (22% vs. 12%), TCOD (0% vs. 10%) and QVA/TCBF (0% vs. 2.4%, absolute increase), with lower resting TCOD found in SL- and HA-Tibetans. Our findings indicate racial but not sex differences in cerebral hemodynamic adaptations to HA, with Tibetans (but not Han) demonstrating an altitude-related change of CBF distribution.

  14. Reduced cerebral blood flow and oxygen metabolism in extremely preterm neonates with low-grade germinal matrix- intraventricular hemorrhage

    Science.gov (United States)

    Lin, Pei-Yi; Hagan, Katherine; Fenoglio, Angela; Grant, P. Ellen; Franceschini, Maria Angela

    2016-05-01

    Low-grade germinal matrix-intraventricular hemorrhage (GM-IVH) is the most common complication in extremely premature neonates. The occurrence of GM-IVH is highly associated with hemodynamic instability in the premature brain, yet the long-term impact of low-grade GM-IVH on cerebral blood flow and neuronal health have not been fully investigated. We used an innovative combination of frequency-domain near infrared spectroscopy and diffuse correlation spectroscopy (FDNIRS-DCS) to measure cerebral oxygen saturation (SO2) and an index of cerebral blood flow (CBFi) at the infant’s bedside and compute an index of cerebral oxygen metabolism (CMRO2i). We enrolled twenty extremely low gestational age (ELGA) neonates (seven with low-grade GM-IVH) and monitored them weekly until they reached full-term equivalent age. During their hospital stay, we observed consistently lower CBFi and CMRO2i in ELGA neonates with low-grade GM-IVH compared to neonates without hemorrhages. Furthermore, lower CBFi and CMRO2i in the former group persists even after the resolution of the hemorrhage. In contrast, SO2 does not differ between groups. Thus, CBFi and CMRO2i may have better sensitivity than SO2 in detecting GM-IVH-related effects on infant brain development. FDNIRS-DCS methods may have clinical benefit for monitoring the evolution of GM-IVH, evaluating treatment response, and potentially predicting neurodevelopmental outcome.

  15. Noninvasive determination of myocardial blood flow, oxygen consumption and efficiency in normal humans by carbon-11 acetate positron emission tomography imaging

    International Nuclear Information System (INIS)

    Porenta, G.; Cherry, S.; Czernin, J.; Brunken, R.; Kuhle, W.; Hashimoto, T.; Schelbert, H.R.

    1999-01-01

    The aims of this study were: (1) to measure noninvasively and near simultaneously myocardial blood flow, oxygen consumption, and contractile function and (2) to analyze myocardial energy expenditure and efficiency at rest and during dobutamine stress in normal humans. Dynamic and gated carbon-11 acetate positron emission tomography (PET) imaging was performed in 11 normal subjects. The initial uptake of 11 C-acetate was measured to estimate myocardial blood flow. Oxygen consumption was derived from the monoexponential slope of the 11 C-clearance curve recorded during myocardial washout. ECG-gated systolic and diastolic images were acquired during the peak myocardial 11 C activity to measure left ventricular radius, myocardial wall thickness, and long axis length. Myocardial oxygen consumption and parameters of cardiac geometry were used to determine myocardial energetics and cardiac efficiency by tension-area area analysis. Myocardial blood flow averaged 0.8±0.06 ml min -1 g -1 at rest and 1.48±0.15 ml min -1 g -1 during dobutamine stress. Oxygen delivery and consumption were 151±13 and 88±15 μl O 2 min -1 g -1 at rest and increased to 291±31 and 216±31 μl O 2 min -1 g -1 , respectively, during pharmacological stress (P 11 C acetate imaging provides the unique capability to study noninvasively determinants of myocardial energy delivery, expenditure, and efficiency. (orig.)

  16. Blood transfusion improves renal oxygenation and renal function in sepsis-induced acute kidney injury in rats

    NARCIS (Netherlands)

    L. Zafrani (Lara); B. Ergin (Bulent); Kapucu, A. (Aysegul); C. Ince (Can)

    2016-01-01

    textabstractBackground: The effects of blood transfusion on renal microcirculation during sepsis are unknown. This study aimed to investigate the effect of blood transfusion on renal microvascular oxygenation and renal function during sepsis-induced acute kidney injury. Methods: Twenty-seven Wistar

  17. Blood transfusion improves renal oxygenation and renal function in sepsis-induced acute kidney injury in rats

    NARCIS (Netherlands)

    Zafrani, Lara; Ergin, Bulent; Kapucu, Aysegul; Ince, Can

    2016-01-01

    The effects of blood transfusion on renal microcirculation during sepsis are unknown. This study aimed to investigate the effect of blood transfusion on renal microvascular oxygenation and renal function during sepsis-induced acute kidney injury. Twenty-seven Wistar albino rats were randomized into

  18. Influence of residual oxygen-15-labeled carbon monoxide radioactivity on cerebral blood flow and oxygen extraction fraction in a dual-tracer autoradiographic method.

    Science.gov (United States)

    Iwanishi, Katsuhiro; Watabe, Hiroshi; Hayashi, Takuya; Miyake, Yoshinori; Minato, Kotaro; Iida, Hidehiro

    2009-06-01

    Cerebral blood flow (CBF), cerebral metabolic rate of oxygen (CMRO(2)), oxygen extraction fraction (OEF), and cerebral blood volume (CBV) are quantitatively measured with PET with (15)O gases. Kudomi et al. developed a dual tracer autoradiographic (DARG) protocol that enables the duration of a PET study to be shortened by sequentially administrating (15)O(2) and C(15)O(2) gases. In this protocol, before the sequential PET scan with (15)O(2) and C(15)O(2) gases ((15)O(2)-C(15)O(2) PET scan), a PET scan with C(15)O should be preceded to obtain CBV image. C(15)O has a high affinity for red blood cells and a very slow washout rate, and residual radioactivity from C(15)O might exist during a (15)O(2)-C(15)O(2) PET scan. As the current DARG method assumes no residual C(15)O radioactivity before scanning, we performed computer simulations to evaluate the influence of the residual C(15)O radioactivity on the accuracy of measured CBF and OEF values with DARG method and also proposed a subtraction technique to minimize the error due to the residual C(15)O radioactivity. In the simulation, normal and ischemic conditions were considered. The (15)O(2) and C(15)O(2) PET count curves with the residual C(15)O PET counts were generated by the arterial input function with the residual C(15)O radioactivity. The amounts of residual C(15)O radioactivity were varied by changing the interval between the C(15)O PET scan and (15)O(2)-C(15)O(2) PET scan, and the absolute inhaled radioactivity of the C(15)O gas. Using the simulated input functions and the PET counts, the CBF and OEF were computed by the DARG method. Furthermore, we evaluated a subtraction method that subtracts the influence of the C(15)O gas in the input function and PET counts. Our simulations revealed that the CBF and OEF values were underestimated by the residual C(15)O radioactivity. The magnitude of this underestimation depended on the amount of C(15)O radioactivity and the physiological conditions. This underestimation

  19. Validation of NIRS in measuring tissue hemoglobin concentration and oxygen saturation on ex vivo and isolated limb models

    Science.gov (United States)

    Xu, Xiaorong; Zhu, Wen; Padival, Vikram; Xia, Mengna; Cheng, Xuefeng; Bush, Robin; Christenson, Linda; Chan, Tim; Doherty, Tim; Iatridis, Angelo

    2003-07-01

    Photonify"s tissue spectrometer uses Near-Infrared Spectroscopy for real-time, noninvasive measurement of hemoglobin concentration and oxygen saturation [SO2] of biological tissues. The technology was validated by a series of ex vivo and animal studies. In the ex vivo experiment, a close loop blood circulation system was built, precisely controlling the oxygen saturation and the hemoglobin concentration of a liquid phantom. Photonify"s tissue spectrometer was placed on the surface of the liquid phantom for real time measurement and compared with a gas analyzer, considered the gold standard to measure oxygen saturation and hemoglobin concentration. In the animal experiment, the right hind limb of each dog accepted onto the study was surgically removed. The limb was kept viable by connecting the femoral vein and artery to a blood-primed extracorporeal circuit. Different concentrations of hemoglobin were obtained by adding designated amount of saline solution into the perfusion circuit. Photonify"s tissue spectrometers measured oxygen saturation and hemoglobin concentration at various locations on the limb and compared with gas analyzer results. The test results demonstrated that Photonify"s tissue spectrometers were able to detect the relative changes in tissue oxygen saturation and hemoglobin concentration with a high linear correlation compared to the gas analyzer

  20. Assessing pharmacy students' ability to accurately measure blood pressure using a blood pressure simulator arm.

    Science.gov (United States)

    Bottenberg, Michelle M; Bryant, Ginelle A; Haack, Sally L; North, Andrew M

    2013-06-12

    To compare student accuracy in measuring normal and high blood pressures using a simulator arm. In this prospective, single-blind, study involving third-year pharmacy students, simulator arms were programmed with prespecified normal and high blood pressures. Students measured preset normal and high diastolic and systolic blood pressure using a crossover design. One hundred sixteen students completed both blood pressure measurements. There was a significant difference between the accuracy of high systolic blood pressure (HSBP) measurement and normal systolic blood pressure (NSBP) measurement (mean HSBP difference 8.4 ± 10.9 mmHg vs NSBP 3.6 ± 6.4 mmHg; pdifference between the accuracy of high diastolic blood pressure (HDBP) measurement and normal diastolic blood pressure (NDBP) measurement (mean HDBP difference 6.8 ± 9.6 mmHg vs. mean NDBP difference 4.6 ± 4.5 mmHg; p=0.089). Pharmacy students may need additional instruction and experience with taking high blood pressure measurements to ensure they are able to accurately assess this important vital sign.

  1. Assessing Pharmacy Students’ Ability to Accurately Measure Blood Pressure Using a Blood Pressure Simulator Arm

    Science.gov (United States)

    Bryant, Ginelle A.; Haack, Sally L.; North, Andrew M.

    2013-01-01

    Objective. To compare student accuracy in measuring normal and high blood pressures using a simulator arm. Methods. In this prospective, single-blind, study involving third-year pharmacy students, simulator arms were programmed with prespecified normal and high blood pressures. Students measured preset normal and high diastolic and systolic blood pressure using a crossover design. Results. One hundred sixteen students completed both blood pressure measurements. There was a significant difference between the accuracy of high systolic blood pressure (HSBP) measurement and normal systolic blood pressure (NSBP) measurement (mean HSBP difference 8.4 ± 10.9 mmHg vs NSBP 3.6 ± 6.4 mmHg; pdifference between the accuracy of high diastolic blood pressure (HDBP) measurement and normal diastolic blood pressure (NDBP) measurement (mean HDBP difference 6.8 ± 9.6 mmHg vs. mean NDBP difference 4.6 ± 4.5 mmHg; p=0.089). Conclusions. Pharmacy students may need additional instruction and experience with taking high blood pressure measurements to ensure they are able to accurately assess this important vital sign. PMID:23788809

  2. Colour measurement and white blood cell recognition

    CERN Document Server

    Gelsema, E S

    1972-01-01

    As a part of a collaboration with NEMCH aimed at the automation of the differential white blood cell count, studies have been made of the different possibilities for using colour to help in the recognition process. Results are presented comparing data obtained with a microspectrophotometer and with a simulated three-colour scanner.

  3. Hybrid optical unobtrusive blood pressure measurements

    NARCIS (Netherlands)

    Zhang, G.; Shan, C.; Kirenko, I.; Long, X.; Aarts, R.M.

    2017-01-01

    Blood pressure (BP) is critical in diagnosing certain cardiovascular diseases such as hypertension. Some previous studies have proved that BP can be estimated by pulse transit time (PTT) calculated by a pair of photoplethysmography (PPG) signals at two body sites. Currently, contact PPG (cPPG) and

  4. Hepatic blood flow and splanchnic oxygen consumption in patients with liver failure. Effect of high-volume plasmapheresis.

    Science.gov (United States)

    Clemmesen, J O; Gerbes, A L; Gülberg, V; Hansen, B A; Larsen, F S; Skak, C; Tygstrup, N; Ott, P

    1999-02-01

    Liver failure represents a major therapeutic challenge, and yet basic pathophysiological questions about hepatic perfusion and oxygenation in this condition have been poorly investigated. In this study, hepatic blood flow (HBF) and splanchnic oxygen delivery (DO2, sp) and oxygen consumption (VO2,sp) were assessed in patients with liver failure defined as hepatic encephalopathy grade II or more. Measurements were repeated after high-volume plasmapheresis (HVP) with exchange of 8 to 10 L of plasma. HBF was estimated by use of constant infusion of D-sorbitol and calculated according to Fick's principle from peripheral artery and hepatic vein concentrations. In 14 patients with acute liver failure (ALF), HBF (1.78 +/- 0.78 L/min) and VO2,sp (3.9 +/- 0.9 mmol/min) were higher than in 11 patients without liver disease (1.07 +/- 0.19 L/min, P HVP, HBF increased from 1.67 +/- 0.72 to 2.07 +/- 1.11 L/min (n=11) in ALF, and from 1.89 +/- 1.32 to 2.34 +/- 1.54 L/min (n=7) in AOCLD, P HVP. Blood flow was redirected to the liver as the systemic vascular resistance index increased (1,587 +/- 650 vs. 2, 020 +/- 806 Dyne. s. cm-5. m2, P HVP, but as cardiac output increased from 9.1 +/- 2.8 to 10.1 +/- 2.9 L/min (P HVP (n=18), DO2,sp increased by 15% (P HVP. Changes of ET-1 were positively correlated with changes in HBF (P HVP (P HVP did not correlate. Our data suggest that liver failure is associated with increased HBF and VO2, sp. HVP further increased HBF and DO2,sp but VO2,sp was unchanged, indicating that splanchnic hypoxia was not present.

  5. Carboxylated nanodiamond and re-oxygenation process of gamma irradiated red blood cells

    International Nuclear Information System (INIS)

    Acosta-Elias, M.; Sarabia-Sainz, A.; Silva-Campa, E.; Angulo-Molina, A.; Soto-Puebla, D.; Barboza-Flores, M.; Melendrez, R.; Alvarez-Garcia, S.; Pedroza-Montero, M.; Pedroso-Santana, S.; Santacruz-Gomez, K.; Castaneda, B.

    2015-01-01

    Nanodiamonds (NDs) possess exceptional physical, chemical, and biological properties, which make them suitable for potential biomedical applications. They are biocompatible and their usefulness as effective Raman/fluorescence probes for labeling as well as for drug delivery has been demonstrated. Related to their biocompatibility, the interaction between NDs and red blood cells (RBCs) is of great interest. In this work, the influence of carboxylated NDs (cNDs) in the re-oxygenation capability of both γ-irradiated and stored RBCs was studied. The standard 25 Gy γ dose recommended to prevent transfusion associated graft-versus-host disease was used. A 5-day maximum storage time was used to evaluate the ''storage lesion''. The hemoglobin (Hb) oxygenation state was assessed by Raman microspectroscopy and the morphologic changes on cells were tracked by optical imaging. Our results show that irradiated RBCs have a better re-oxygenation capability and morphological recovery when they are in presence of cNDs. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  6. Carboxylated nanodiamond and re-oxygenation process of gamma irradiated red blood cells

    Energy Technology Data Exchange (ETDEWEB)

    Acosta-Elias, M. [Doctorado en Nanotecnologia, Universidad de Sonora (Mexico); Sarabia-Sainz, A.; Silva-Campa, E.; Angulo-Molina, A.; Soto-Puebla, D.; Barboza-Flores, M.; Melendrez, R.; Alvarez-Garcia, S.; Pedroza-Montero, M. [Departamento de Investigacion en Fisica, Universidad de Sonora, Hermosillo (Mexico); Pedroso-Santana, S. [Doctorado en Ciencias (Fisica), Universidad de Sonora, Hermosillo (Mexico); Santacruz-Gomez, K.; Castaneda, B. [Departamento de Fisica, Universidad de Sonora, Hermosillo (Mexico)

    2015-11-15

    Nanodiamonds (NDs) possess exceptional physical, chemical, and biological properties, which make them suitable for potential biomedical applications. They are biocompatible and their usefulness as effective Raman/fluorescence probes for labeling as well as for drug delivery has been demonstrated. Related to their biocompatibility, the interaction between NDs and red blood cells (RBCs) is of great interest. In this work, the influence of carboxylated NDs (cNDs) in the re-oxygenation capability of both γ-irradiated and stored RBCs was studied. The standard 25 Gy γ dose recommended to prevent transfusion associated graft-versus-host disease was used. A 5-day maximum storage time was used to evaluate the ''storage lesion''. The hemoglobin (Hb) oxygenation state was assessed by Raman microspectroscopy and the morphologic changes on cells were tracked by optical imaging. Our results show that irradiated RBCs have a better re-oxygenation capability and morphological recovery when they are in presence of cNDs. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  7. Prefrontal oxygenation correlates to the responses in facial skin blood flows during exposure to pleasantly charged movie

    OpenAIRE

    Matsukawa, Kanji; Endo, Kana; Asahara, Ryota; Yoshikawa, Miho; Kusunoki, Shinya; Ishida, Tomoko

    2017-01-01

    Abstract Our laboratory reported that facial skin blood flow may serve as a sensitive tool to assess an emotional status. Cerebral neural correlates during emotional interventions should be sought in relation to the changes in facial skin blood flow. To test the hypothesis that prefrontal activity has positive relation to the changes in facial skin blood flow during emotionally charged stimulation, we examined the dynamic changes in prefrontal oxygenation (with near‐infrared spectroscopy) and...

  8. Time-Dependent Behavior of Microvascular Blood Flow and Oxygenation: A Predictor of Functional Outcomes.

    Science.gov (United States)

    Kuliga, Katarzyna Z; Gush, Rodney; Clough, Geraldine F; Chipperfield, Andrew John

    2018-05-01

    This study investigates the time-dependent behaviour and algorithmic complexity of low-frequency periodic oscillations in blood flux (BF) and oxygenation signals from the microvasculature. Microvascular BF and oxygenation (OXY: oxyHb, deoxyHb, totalHb, and SO 2 %) was recorded from 15 healthy young adult males using combined laser Doppler fluximetry and white light spectroscopy with local skin temperature clamped to 33  °C and during local thermal hyperaemia (LTH) at 43 °C. Power spectral density of the BF and OXY signals was evaluated within the frequency range (0.0095-1.6 Hz). Signal complexity was determined using the Lempel-Ziv (LZ) algorithm. Fold increase in BF during LTH was 15.6 (10.3, 22.8) and in OxyHb 4.8 (3.5, 5.9) (median, range). All BF and OXY signals exhibited multiple oscillatory components with clear differences in signal power distribution across frequency bands at 33 and 43 °C. Significant reduction in the intrinsic variability and complexity of the microvascular signals during LTH was found, with mean LZ complexity of BF and OxyHb falling by 25% and 49%, respectively ( ). These results provide corroboration that in human skin microvascular blood flow and oxygenation are influenced by multiple time-varying oscillators that adapt to local influences and become more predictable during increased haemodynamic flow. Recent evidence strongly suggests that the inability of microvascular networks to adapt to an imposed stressor is symptomatic of disease risk which might be assessed via BF and OXY via the combination signal analysis techniques described here.

  9. Mannitol increases renal blood flow and maintains filtration fraction and oxygenation in postoperative acute kidney injury: a prospective interventional study.

    Science.gov (United States)

    Bragadottir, Gudrun; Redfors, Bengt; Ricksten, Sven-Erik

    2012-08-17

    Acute kidney injury (AKI), which is a major complication after cardiovascular surgery, is associated with significant morbidity and mortality. Diuretic agents are frequently used to improve urine output and to facilitate fluid management in these patients. Mannitol, an osmotic diuretic, is used in the perioperative setting in the belief that it exerts reno-protective properties. In a recent study on uncomplicated postcardiac-surgery patients with normal renal function, mannitol increased glomerular filtration rate (GFR), possibly by a deswelling effect on tubular cells. Furthermore, experimental studies have previously shown that renal ischemia causes an endothelial cell injury and dysfunction followed by endothelial cell edema. We studied the effects of mannitol on renal blood flow (RBF), glomerular filtration rate (GFR), renal oxygen consumption (RVO2), and extraction (RO2Ex) in early, ischemic AKI after cardiac surgery. Eleven patients with AKI were studied during propofol sedation and mechanical ventilation 2 to 6 days after complicated cardiac surgery. All patients had severe heart failure treated with one (100%) or two (73%) inotropic agents and intraaortic balloon pump (36%). Systemic hemodynamics were measured with a pulmonary artery catheter. RBF and renal filtration fraction (FF) were measured by the renal vein thermo-dilution technique and by renal extraction of chromium-51-ethylenediaminetetraacetic acid (51Cr-EDTA), respectively. GFR was calculated as the product of FF and renal plasma flow RBF × (1-hematocrit). RVO2 and RO2Ex were calculated from arterial and renal vein blood samples according to standard formulae. After control measurements, a bolus dose of mannitol, 225 mg/kg, was given, followed by an infusion at a rate of 75 mg/kg/h for two 30-minute periods. Mannitol did not affect cardiac index or cardiac filling pressures. Mannitol increased urine flow by 61% (P renal vascular resistance (P renal FF. Mannitol treatment of postoperative AKI

  10. Facultative Stabilization Pond: Measuring Biological Oxygen Demand using Mathematical Approaches

    Science.gov (United States)

    Wira S, Ihsan; Sunarsih, Sunarsih

    2018-02-01

    Pollution is a man-made phenomenon. Some pollutants which discharged directly to the environment could create serious pollution problems. Untreated wastewater will cause contamination and even pollution on the water body. Biological Oxygen Demand (BOD) is the amount of oxygen required for the oxidation by bacteria. The higher the BOD concentration, the greater the organic matter would be. The purpose of this study was to predict the value of BOD contained in wastewater. Mathematical modeling methods were chosen in this study to depict and predict the BOD values contained in facultative wastewater stabilization ponds. Measurements of sampling data were carried out to validate the model. The results of this study indicated that a mathematical approach can be applied to predict the BOD contained in the facultative wastewater stabilization ponds. The model was validated using Absolute Means Error with 10% tolerance limit, and AME for model was 7.38% (< 10%), so the model is valid. Furthermore, a mathematical approach can also be applied to illustrate and predict the contents of wastewater.

  11. Blood pressure measurements in the ankle are not equivalent to blood pressure measurements in the arm.

    Science.gov (United States)

    Goldstein, Lara Nicole; Wells, Mike; Sliwa, Karen

    2014-07-25

    Blood pressure (BP) is often measured on the ankle in the emergency department (ED), but this has never been shown to be an acceptable alternative to measurements performed on the arm. To establish whether the differences between arm and ankle non-invasive BP measurements were clinically relevant (i.e. a difference of ≥10 mmHg). This was a prospective cross-sectional study in an urban ED making use of a convenience sample of 201 patients (18 - 50 years of age) who were not in need of emergency medical treatment. BP was measured in the supine position on both arms and ankles with the correct size cuff according to the manufacturer's guidelines. The arm and ankle BP measurements were compared. There was a clinically and statistically significant difference between arm and ankle systolic BP (SBP) and mean arterial pressure (MAP) (-13 mmHg, 95% confidence interval (CI) -28 - 1 mmHg and -5 mmHg, 95% CI -13 - 4 mmHg, respectively), with less difference in diastolic BP (DBP) (2 mmHg, 95% CI -7 - 10 mmHg). Only 37% of SBP measurements and 83% of MAP measurements were within an error range of 10 mmHg, while 95% of DBP measurements agreed within 10 mmHg. While the average differences (or the bias) were generally not large, large variations in individual patients (indicating poor precision) made the prediction of arm BP from ankle measurements unreliable. Ankle BP cannot be used as a substitute for arm BP in the ED.

  12. Whole body [O-15]water pharmacokinetics measured in blood

    NARCIS (Netherlands)

    Maguire, RP; Spyrou, NM; Leenders, KL

    A simple pharmacokinetic model to explain the time course of [0-15]water in human whole blood after bolus injection is described. The model has been derived from measurements in twelve healthy volunteers who were measured repeatedly, resulting in 67 datasets, made in the context of PET blood flow

  13. The optimal scheme of self blood pressure measurement as determined from ambulatory blood pressure recordings

    NARCIS (Netherlands)

    Verberk, Willem J.; Kroon, Abraham A.; Kessels, Alfons G. H.; Lenders, Jacques W. M.; Thien, Theo; van Montfrans, Gert A.; Smit, Andries J.; de Leeuw, Peter W.

    Objective To determine how many self-measurements of blood pressure (BP) should be taken at home in order to obtain a reliable estimate of a patient's BP. Design Participants performed self blood pressure measurement (SBPM) for 7 days (triplicate morning and evening readings). In all of them, office

  14. The determination of chromium-50 in human blood and its utilization for blood volume measurements

    International Nuclear Information System (INIS)

    Zeisler, R.; Young, I.

    1986-01-01

    Possible relationships between insufficient blood volume increases during pregnancy and infant mortality could be established with an adequate measurement procedure. An accurate and precise technique for blood volume measurements has been found in the isotope dilution technique using chromium-51 as a label for red blood cells. However, in a study involving pregnant women, only stable isotopes can be used for labeling. Stable chromium-50 can be determined in total blood samples before and after dilution experiments by neutron activation analysis (NAA) or mass spectrometry. However, both techniques may be affected by insufficient sensitivity and contamination problems at the inherently low natural chromium concentrations to be measured in the blood. NAA procedures involving irradiations with highly thermalized neutrons at a fluence rate of 2x10 13 n/cm 2 xs and low background gamma spectrometry are applied to the analysis of total blood. Natural levels of chromium-50 in human and animal blood have been found to be <0.1 ng/mL; i.e., total chromium levels of <3 ng/mL. Based on the NAA procedure, a new approach to the blood volume measurement via chromium-50 isotope dilution has been developed which utilizes the ratio of the induced activities of chromium-51 to the iron-59 in three blood samples taken from each individual, namely blank, labeled and diluted labeled blood. (author)

  15. Acute effects of nicotine and smoking on blood flow, tissue oxygen, and aerobe metabolism of the skin and subcutis

    DEFF Research Database (Denmark)

    Sørensen, Lars Tue; Jørgensen, Stig; Petersen, Lars J

    2009-01-01

    BACKGROUND: Nicotine released from tobacco smoke causing reduction in blood flow has been suggested as causative for postoperative wound complications in smokers, but the mechanism remains unknown. MATERIALS AND METHODS: In eight healthy male smokers and eight ex-smokers, the cutaneous and subcut......BACKGROUND: Nicotine released from tobacco smoke causing reduction in blood flow has been suggested as causative for postoperative wound complications in smokers, but the mechanism remains unknown. MATERIALS AND METHODS: In eight healthy male smokers and eight ex-smokers, the cutaneous...... and subcutaneous blood flow (QBF, SqBF) was assessed by Laser Doppler and 133Xe clearance. Tissue oxygen tension (TO(2)) was measured by a LICOX O(2)-electrode. Tissue glucose and lactate (Tgluc, Tlact) were assessed by microdialysis. The parameters were studied after intravenous infusion of 1.0 mg nicotine......, smoking of one cigarette, arterial occlusion, and reperfusion. RESULTS: Nicotine infusion decreased SqBF from 4.2 +/- 2.0 to 3.1 +/- 1.2 mL/100 g tissue/min (P

  16. Measurement of brain oxygenation changes using dynamic T1-weighted imaging

    DEFF Research Database (Denmark)

    Haddock, Bryan; Larsson, Henrik B W; Hansen, Adam E

    2013-01-01

    Magnetic resonance imaging (MRI) has proven useful in evaluating oxygenation in several types of tissue and blood. This study evaluates brain tissue oxygenation changes between normoxia and hyperoxia in healthy subjects using dynamic T1 and T2*-weighted imaging sequences. The change in FiO2 induced...... by hyperoxia caused a significant decrease in T1. A model to determine changes in tissue oxygen tension from the T1-weighted MRI signal is presented based on previous findings that T1 is sensitive to oxygen tension whereas T2* is sensitive to blood saturation. The two sequences produce results with different...... regional and temporal dynamics. These differences combined with results from simulations of the T1 signal intensities, indicate an increase in extravascular oxygen tension during hyperoxia. This study concludes that T1 and T2* responses to FiO2 serve as independent biomarkers of oxygen physiology...

  17. Skeletal muscle blood flow and oxygen uptake at rest and during exercise in humans: a PET study with nitric oxide and cyclooxygenase inhibition

    DEFF Research Database (Denmark)

    Heinonen, Ilkka; Saltin, Bengt; Kemppainen, Jukka

    2011-01-01

    The aim of the present study was to determine the effect of nitric oxide and prostanoids on microcirculation and oxygen uptake specifically in the active skeletal muscle by use of positron emission tomography (PET). Healthy males performed 3 five min bouts of light knee-extensor exercise. Skeletal...... muscle blood flow and oxygen uptake were measured at rest and during the exercise using PET with H(2)O(15) and (15)O(2) during: 1) control conditions; 2) nitric oxide synthase (NOS) inhibition by arterial infusion of L-NMMA and 3) combined NOS and cyclooxygenase (COX) inhibition by arterial infusion of L...

  18. Measurement of organ blood flow using tritiated water. II. Uterine blood flow in conscious pregnant ewes

    International Nuclear Information System (INIS)

    Brown, B.W.; Oddy, V.H.; Jones, A.W.

    1982-01-01

    Total uterine blood flow was measured with a tritiated water (TOH) diffusion method and with radioactive microspheres in six, conscious, pregnant ewes. With continuous infusion of TOH, equilibrium between the TOH concentration in utero-ovarian venous blood and arterial blood was attained within 50 min of the start of the infusion. The concentration of TOH in uterine and foetal tissue and in foetal blood water was the same as that in uterine venous water by 40 min; at this time, the concentration of TOH in the water of amniotic and allantoic fluids was 96% of that in uterine venous blood water. Estimates of total uterine blood flow obtained using TOH were highly correlated with those obtained with microspheres and the corresponding mean flow values obtained with the two techniques did not significantly differ. The percentage of the total uterine blood flow passing through arteriovenous anastomoses ranged from 1.4 to 3.3%

  19. Cerebral tissue oxygenation index and superior vena cava blood flow in the very low birth weight infant.

    LENUS (Irish Health Repository)

    Moran, M

    2012-02-01

    BACKGROUND: Superior vena cava (SVC) flow assesses blood flow from the upper body, including the brain. Near infrared spectroscopy (NIRS) provides information on brain perfusion and oxygenation. AIM: To assess the relationship between cerebral tissue oxygenation index (cTOI) and cardiac output measures in the very low birth weight (VLBW) infant in the first day of life. METHODS: A prospective observational cohort study. Neonates with birth weight less than 1500 g (VLBW) were eligible for enrollment. Newborns with congenital heart disease, major congenital malformations and greater than Papile grade1 Intraventricular Haemorrhage on day 1 of life were excluded. Echocardiographic evaluation of SVC flow was performed in the first 24 h of life. Low SVC flow states were defined as a flow less than 40 mL\\/kg\\/min. cTOI was measured using NIRO 200 Hamamatsu. RESULTS: Twenty-seven VLBW neonates had both echocardiography and NIRS performed. The median (range) gestation was 29\\/40 (25 + 3 to 31 + 5 weeks) and median birth weight was 1.2 kg (0.57-1.48 kg). The mean (SD) TOI was 68.1 (7.9)%. The mean (SD) SVC flow was 70.36(39.5) mLs\\/kg\\/min. The correlation coefficient of cerebral tissue oxygenation and SVC flow was r = 0.53, p-value 0.005. There was a poor correlation between right and left ventricular output and cTOI which is not surprising considering the influence of intra- and extracardiac shunts. CONCLUSION: There is a positive relationship between cerebral TOI values and SVC flow in the very low birth infant on day one of life.

  20. Manual or automated measuring of antipsychotics' chemical oxygen demand.

    Science.gov (United States)

    Pereira, Sarah A P; Costa, Susana P F; Cunha, Edite; Passos, Marieta L C; Araújo, André R S T; Saraiva, M Lúcia M F S

    2018-05-15

    Antipsychotic (AP) drugs are becoming accumulated in terrestrial and aqueous resources due to their actual consumption. Thus, the search of methods for assessing the contamination load of these drugs is mandatory. The COD is a key parameter used for monitoring water quality upon the assessment of the effect of polluting agents on the oxygen level. Thus, the present work aims to assess the chemical oxygen demand (COD) levels of several typical and atypical antipsychotic drugs in order to obtain structure-activity relationships. It was implemented the titrimetric method with potassium dichromate as oxidant and a digestion step of 2h, followed by the measurement of remained unreduced dichromate by titration. After that, an automated sequential injection analysis (SIA) method was, also, used aiming to overcome some drawbacks of the titrimetric method. The results obtained showed a relationship between the chemical structures of antipsychotic drugs and their COD values, where the presence of aromatic rings and oxidable groups give higher COD values. It was obtained a good compliance between the results of the reference batch procedure and the SIA system, and the APs were clustered in two groups, with the values ratio between the methodologies, of 2 or 4, in the case of lower or higher COD values, respectively. The SIA methodology is capable of operating as a screening method, in any stage of a synthetic process, being also more environmentally friendly, and cost-effective. Besides, the studies presented open promising perspectives for the improvement of the effectiveness of pharmaceutical removal from the waste effluents, by assessing COD values. Copyright © 2018 Elsevier Inc. All rights reserved.

  1. Arterial blood gases and oxygen content in climbers on Mount Everest

    NARCIS (Netherlands)

    Grocott, Michael P. W.; Martin, Daniel S.; Levett, Denny Z. H.; McMorrow, Roger; Windsor, Jeremy; Montgomery, Hugh E.; Ahuja, V.; Aref-Adib, G.; Burnham, R.; Chisholm, A.; Clarke, K.; Coates, D.; Coates, M.; Cook, D.; Cox, M.; Dhillon, S.; Dougall, C.; Doyle, P.; Duncan, P.; Edsell, M.; Edwards, L.; Evans, L.; Gardiner, P.; Grocott, M.; Gunning, P.; Hart, N.; Harrington, J.; Harvey, J.; Holloway, C.; Howard, D.; Hurlbut, D.; Imray, C.; Ince, C.; Jonas, M.; van der Kaaij, J.; Khosravi, M.; Kolfschoten, N.; Levett, D.; Luery, H.; Luks, A.; Martin, D.; McMorrow, R.; Meale, P.; Mitchell, K.; Montgomery, H.; Morgan, G.; Morgan, J.; Murray, A.; Mythen, M.; Newman, S.

    2009-01-01

    BACKGROUND: The level of environmental hypobaric hypoxia that affects climbers at the summit of Mount Everest (8848 m [29,029 ft]) is close to the limit of tolerance by humans. We performed direct field measurements of arterial blood gases in climbers breathing ambient air on Mount Everest. METHODS:

  2. Design a Wearable Device for Blood Oxygen Concentration and Temporal Heart Beat Rate

    Science.gov (United States)

    Myint, Cho Zin; Barsoum, Nader; Ing, Wong Kiing

    2010-06-01

    The wireless network technology is increasingly important in healthcare as a result of the aging population and the tendency to acquire chronic disease such as heart attack, high blood pressure amongst the elderly. A wireless sensor network system that has the capability to monitor physiological sign such as SpO2 (Saturation of Arterial Oxygen) and heart beat rate in real-time from the human's body is highlighted in this study. This research is to design a prototype sensor network hardware, which consists of microcontroller PIC18F series and transceiver unit. The sensor is corporate into a wearable body sensor network which is small in size and easy to use. The sensor allows a non invasive, real time method to provide information regarding the health of the body. This enables a more efficient and economical means for managing the health care of the population.

  3. Continuous Perfusion of Saphenous Vein by Oxygenated Blood during Beating Coronary Surgery

    Directory of Open Access Journals (Sweden)

    Mohammad Hossein Mandegar

    2015-09-01

    Full Text Available Background: The saphenous vein remains the most commonly used conduit for coronary artery bypass surgery (CABG. However, the long-term success of surgical revascularization is largely limited by development of occlusion in vein grafts. Objectives: We sought to reduce graft ischemia by maintaining the blood flow into the harvested vein throughout surgery at lowest costs and without special devices. Patients and Methods: This study was conducted on three hundred patients aged 58.5 ± 8 years undergoing elective first-time off-pump CABG with saphenous veins. Results: In addition to preserving nutritional materials and oxygen, the veins harvested via this novel technique did not go into spasm and were not subjected to high-pressure distension, eventually resulting in minimal damage to the endothelium. Conclusions: This technique confers favorable myocardial function and protection in the presence of left ventricular dysfunction, especially in elderly patients.

  4. Critical evaluation of blood volume measurements during hemodialysis.

    Science.gov (United States)

    Dasselaar, Judith J; van der Sande, Frank M; Franssen, Casper F M

    2012-01-01

    Devices that continuously measure relative blood volume (RBV) changes during hemodialysis (HD) are increasingly used for the prevention of dialysis hypotension and fine-tuning of dry weight. However, RBV measurements are subject to various limitations. First, RBV devices provide information on relative blood volume changes but not on absolute blood volume. Since blood volume varies with the hydration status, identical reductions of RBV may result in very different absolute blood volumes at the end of HD. Second, RBV changes underestimate the change of total blood volume due to translocation of lower-hematocrit blood from the microcirculation to the central circulation. Third, changes in posture before and during HD, food intake, exercise, and administration of intravenous fluids may influence the validity of the RBV measurement. Fourth, results obtained by various RBV devices show large interdevice differences. Finally, although a fall in blood volume is an important factor in dialysis hypotension, frank dialysis hypotension only occurs when the cardiovascular compensatory mechanisms can no longer compensate for the reduction in blood volume. Therefore, the dialysis staff should not exclusively focus on RBV, but also search for opportunities in the dialysis prescription to facilitate cardiovascular compensatory mechanisms, e.g. by lowering dialysate temperature. In the opinion of the authors, routine RBV monitoring should be used with caution until the major conceptual and methodological problems that are inherent to the indirect RBV estimation are clarified. Copyright © 2012 S. Karger AG, Basel.

  5. Reduction of blood oxygen levels enhances postprandial cardiac hypertrophy in Burmese python (Python bivittatus).

    Science.gov (United States)

    Slay, Christopher E; Enok, Sanne; Hicks, James W; Wang, Tobias

    2014-05-15

    Physiological cardiac hypertrophy is characterized by reversible enlargement of cardiomyocytes and changes in chamber architecture, which increase stroke volume and via augmented convective oxygen transport. Cardiac hypertrophy is known to occur in response to repeated elevations of O2 demand and/or reduced O2 supply in several species of vertebrate ectotherms, including postprandial Burmese pythons (Python bivittatus). Recent data suggest postprandial cardiac hypertrophy in P. bivittatus is a facultative rather than obligatory response to digestion, though the triggers of this response are unknown. Here, we hypothesized that an O2 supply-demand mismatch stimulates postprandial cardiac enlargement in Burmese pythons. To test this hypothesis, we rendered animals anemic prior to feeding, essentially halving blood oxygen content during the postprandial period. Fed anemic animals had heart rates 126% higher than those of fasted controls, which, coupled with a 71% increase in mean arterial pressure, suggests fed anemic animals were experiencing significantly elevated cardiac work. We found significant cardiac hypertrophy in fed anemic animals, which exhibited ventricles 39% larger than those of fasted controls and 28% larger than in fed controls. These findings support our hypothesis that those animals with a greater magnitude of O2 supply-demand mismatch exhibit the largest hearts. The 'low O2 signal' stimulating postprandial cardiac hypertrophy is likely mediated by elevated ventricular wall stress associated with postprandial hemodynamics. © 2014. Published by The Company of Biologists Ltd.

  6. TREATMENT OF HYPERTENSION USING TELEMEDICAL HOME BLOOD PRESSURE MEASUREMENTS

    DEFF Research Database (Denmark)

    Hoffmann-Petersen, N; Lauritzen, T; Bech, J N

    2015-01-01

    OBJECTIVE: Telemonitoring of home blood pressure measurements (TBPM) is a new and promising supplement to diagnosis, control and treatment of hypertension. We wanted to compare the outcome of antihypertensive treatment based on TBPM and conventional monitoring of blood pressure. DESIGN AND METHOD...... of the measurements and subsequent communication by telephone or E-mail. In the control group, patients received usual care. Primary outcome was reduction in daytime ambulatory blood pressure measurements (ABPM) from baseline to 3 months' follow-up. RESULTS: In both groups, daytime ABPM decreased significantly....../181), p = 0.34. Blood pressure reduction in the TBPM group varied with the different practices. CONCLUSIONS: No further reduction in ABPM or number of patients reaching blood pressure targets was observed when electronic transmission of TBPM was applied in the treatment of hypertension by GPs. Thus...

  7. Blood pressure measurement: one arm or both arm?

    Science.gov (United States)

    Kulkarni, Prasad K; Shekhar, Susheela; Reddy, B N; Nirmala, B C

    2011-09-01

    Guidelines for measuring blood pressure includes measurement of blood pressure on both arms but it is often ignored. Our case report aims at highlighting the need follow the guidelines. A 60 year old 59 kg weighing male asymptomatic patient without any comobidities was posted for bilateral inguinal hernia repair. The interarm blood pressure difference was discovered incidentally during his preanaesthetic evalution. On further evaluation patient was found to be having subclavian stenosis on left side which was asymptomatic. Intraoperative and post operative period was uneventful. Blood pressure measurement should be done in accordance with the stipulated guidelines. Inter arm blood pressure difference should be noted in all patients as not only for diagnosis and treatment of hypertension but also as a tool to diagnose asymptomatic peripheral vascular disesase.

  8. Self-monitoring of blood glucose measurements and glycaemic ...

    African Journals Online (AJOL)

    Background. Intensive diabetes management requires intensive insulin treatment and self-monitoring of blood glucose (SMBG) measurements to obtain immediate information on the status of the blood glucose level and to obtain data for pattern analysis on which meal planning, insulin and lifestyle adjustments can be ...

  9. Measurement of absolute bone blood flow by positron emission tomography

    Energy Technology Data Exchange (ETDEWEB)

    Nahmias, C.; Cockshott, W.P.; Garnett, E.S.; Belbeck, L.W.

    1986-03-01

    A method of measuring bone blood flow has been developed using /sup 18/F sodium fluoride and positron emission tomography. The blood flow levels are in line with those obtained experimentally from microsphere embolisation. This investigative method could be applied to elucidate a number of clinical questions involving bone perfusion.

  10. Blood pressure self-measurement in the obstetric waiting room

    DEFF Research Database (Denmark)

    Wagner, Stefan; Kamper, Christina H.; Toftegaard, Thomas Skjødeberg

    2013-01-01

    a reliable blood pressure reading. Results: We found that the patients did not adhere to given instructions when performing blood pressure self-measurement in the waiting room. None of the 81 patients adhered to all six inves- tigated recommendations, while around a quarter adhered to five out of six...

  11. Perioperative blood saving measures in total hip and knee arthroplasty

    NARCIS (Netherlands)

    Horstmann, W.G.

    2011-01-01

    This dissertation explores and discusses different aspects of blood loss and blood-saving measures in total hip and knee arthroplasty. Background: Worldwide, approximately 1 million total hip and 1 million total knee prostheses are implanted each year. Total hip arthroplasty and total

  12. CELL RESPIRATION STUDIES : II. A COMPARATIVE STUDY OF THE OXYGEN CONSUMPTION OF BLOOD FROM NORMAL INDIVIDUALS AND PATIENTS WITH INCREASED LEUCOCYTE COUNTS (SEPSIS; CHRONIC MYELOGENOUS LEUCEMIA).

    Science.gov (United States)

    Daland, G A; Isaacs, R

    1927-06-30

    1. The oxygen consumption of blood of normal individuals, when the hemoglobin is saturated with oxygen, is practically zero within the limits of experimental error of the microspirometer used. 2. The oxygen consumed in a microspirometer by the blood of patients with chronic myelogenous leucemia with a high white blood cell count, and of one with leucocytosis from sepsis, was proportional to the number of adult polymorphonuclear neutrophils in the blood. 3. No correlation could be made between the rate of oxygen absorption and the total number of white blood cells in the blood, or the total number of immature cells, or the number of red blood cells, or the amount of oxyhemoglobin. 4. The blood of patients with chronic myelogenous leucemia continued to use oxygen in the microspirometer longer than that of normal individuals, and the hemoglobin, in the leucemic bloods, became desaturated even though exposed to air. 5. In blood in which the bulk. of the cells were immature and the mature cells few, the oxygen consumption was lower than in blood in which the mature cells predominated. The rate of oxygen consumption of the immature cells was relatively low as compared to the mature. 6. The slower rate of oxygen absorption by the immature leucocytes in chronic myelogenous leucemia as compared to the mature cells, places them, in accord with Warburg's reports, in the class of the malignant tissues in this respect rather than in the group of young or embryonic cells.

  13. Our experience of blood flow measurements using radioactive tracers

    International Nuclear Information System (INIS)

    Danet, Bernard.

    1974-01-01

    A critical study of blood flow measuring methods is proposed. After a review of the various diffusible and non-diffusible radioactive tracers and the corresponding detector systems, the principles which allow to measure blood flow from the data so obtained, are studied. There is a different principle of flow measurement for each type of tracer. The theory of flow measurement using non-diffusible tracers (human serum albumin labelled with 131 I or sup(99m)Tc, 113 In-labelled siderophiline) and its application to cardiac flow measurement are described first. Then the theory of flow measurement using diffusible tracers ( 133 Xe, 85 Kr) and its application to measurement of blood flow through tissues (muscles and kidney particularly) are described. A personal experience of this various flow measurements is reported. The results obtained, the difficulties encountered and the improvments proposed are developed [fr

  14. [Comparison of invasive blood pressure measurement in the aorta with indirect oscillometric blood pressure measurement at the wrist and forearm].

    Science.gov (United States)

    Saul, F; Aristidou, Y; Klaus, D; Wiemeyer, A; Lösse, B

    1995-09-01

    Indirectly measured blood pressure at the wrist or upper arm was compared with directly measured values in the aortic arch during routinely performed diagnostic cardiac catheterization in 100 patients (31-80 years, mean 59.3 years, 60% males). The noninvasive measurements were carried out by oscillometric devices, NAiS Blood Pressure Watch for measurements at the wrist, and Hestia OZ80 at the upper arm. Systolic blood pressure measured at the wrist was 4.3 +/- 14.1 mm Hg, and the diastolic value 6.0 +/- 8.9 mm Hg higher than when measured at the aortic arch; the difference was significant in both cases. Correlation coefficients were 0.85 for systolic and 0.71 for diastolic blood pressure. In 16% of the patients the systolic blood pressure at the wrist differed more than +/- 20 mm Hg. The diastolic blood pressure at the wrist measured more than +/- 20 mm Hg higher than in the aorta in 5% of the patients. At the upper arm mean systolic values were not different to the aorta. The diastolic pressure was 9.3 +/- 9.8 mm Hg higher in the aorta than at the upper arm. To verify the accuracy of values measured with the NAiS Blood Pressure Watch compared with the standard technique at the upper arm, sequential measurements were made at wrist and ipsilateral upper arm in the same group of 100 patients. The systolic blood pressure at the left wrist was 3.4 +/- 13.3 mm Hg higher and the diastolic pressure 3.8 +/- 9.5 mm Hg lower than at the upper arm. Only 53% of systolic values lay within a range of +/- 10 mm Hg. The correspondence between wrist and upper arm values was better for diastolic blood pressure, the values differing by less than +/- 10 mm Hg in two-thirds of patients. Self-measurement of arterial blood pressure with an oscillometric device at the wrist can be recommended only in individual cases with a difference of simultaneously measured values at the upper arm of less than +/- 10 mm Hg for systolic and diastolic blood pressures. The standard method for indirectly

  15. Numerical Investigation of Oxygenated and Deoxygenated Blood Flow through a Tapered Stenosed Arteries in Magnetic Field.

    Directory of Open Access Journals (Sweden)

    M Y Abdollahzadeh Jamalabadi

    Full Text Available Current paper is focused on transient modeling of blood flow through a tapered stenosed arteries surrounded a by solenoid under the presence of heat transfer. The oxygenated and deoxygenated blood are considered here by the Newtonian and Non-Newtonian fluid (power law and Carreau-Yasuda models. The governing equations of bio magnetic fluid flow for an incompressible, laminar, homogeneous, non-Newtonian are solved by finite volume method with SIMPLE algorithm for structured grid. Both magnetization and electric current source terms are well thought-out in momentum and energy equations. The effects of fluid viscosity model, Hartmann number, and magnetic number on wall shear stress, shearing stress at the stenosis throat and maximum temperature of the system are investigated and are optimized. The current study results are in agreement with some of the existing findings in the literature and are useful in thermal and mechanical design of spatially varying magnets to control the drug delivery and biomagnetic fluid flows through tapered arteries.

  16. Longitudinal Assessment of Renal Perfusion and Oxygenation in Transplant Donor-Recipient Pairs Using Arterial Spin Labeling and Blood Oxygen Level-Dependent Magnetic Resonance Imaging.

    Science.gov (United States)

    Niles, David J; Artz, Nathan S; Djamali, Arjang; Sadowski, Elizabeth A; Grist, Thomas M; Fain, Sean B

    2016-02-01

    The aims of this study were to assess renal function in kidney transplant recipients and their respective donors over 2 years using arterial spin labeling (ASL) and blood oxygen level-dependent (BOLD) magnetic resonance imaging (MRI) and to prospectively evaluate the effect of losartan on functional MRI measures in recipients. The study included 15 matched pairs of renal transplant donors and recipients. Arterial spin labeling and BOLD MRI of the kidneys were performed on donors before transplant surgery (baseline) and on both donors and recipients at 3 months, 1 year, and 2 years after transplant. After 3 months, 7 of the 15 recipients were prescribed 25 to 50 mg/d losartan for the remainder of the study. A linear mixed-effects model was used to evaluate perfusion, R2*, estimated glomerular filtration rate, and fractional excretion of sodium for changes across time or associated with losartan treatment. In donors, cortical perfusion in the remaining kidney decreased by 50 ± 19 mL/min per 100 g (11.8%) between baseline and 2 years (P donors and to 14.6 ± 4.3 mL/min per 1.73 m (33.3%; P donors, and they indicate a potentially beneficial effect of losartan in recipients.

  17. A pilot study of a new spectrophotometry device to measure tissue oxygen saturation.

    Science.gov (United States)

    Abel, Gemma; Allen, John; Drinnan, Michael

    2014-09-01

    Tissue oxygen saturation (SO2) measurements have the potential for far wider use than at present but are limited by device availability and portability for many potential applications. A device based on a small, low-cost general-purpose spectrophotometer (the Harrison device) might facilitate wider use. The aim of this study was to compare the Harrison device with a commercial instrument, the LEA O2C.Measurements were carried out on the forearm and finger of 20 healthy volunteers, using a blood pressure cuff on the upper arm to induce different levels of oxygenation. Repeatability of both devices was assessed, and the Bland-Altman method was used to assess agreement between them.The devices showed agreement in overall tracking of changes in SO2. Test-retest agreement for the Harrison device was worse than for O2C, with SD repeatability of 10.6% (forearm) or 18.6% (finger). There was no overall bias between devices, but mean (SD) difference of 1.2 (11.8%) (forearm) or 4.4 (11.5%) (finger) were outside of a clinically acceptable range.Disagreements were attributed to the stability of the Harrison probe and the natural SO2 variations across the skin surface increasing the random error. Therefore, though not equivalent to the LEA O2C, a probe redesign and averaged measurements may help establish the Harrison device as a low cost alternative.

  18. A pilot study of a new spectrophotometry device to measure tissue oxygen saturation

    International Nuclear Information System (INIS)

    Abel, Gemma; Allen, John; Drinnan, Michael

    2014-01-01

    Tissue oxygen saturation (SO2) measurements have the potential for far wider use than at present but are limited by device availability and portability for many potential applications. A device based on a small, low-cost general-purpose spectrophotometer (the Harrison device) might facilitate wider use. The aim of this study was to compare the Harrison device with a commercial instrument, the LEA O2C. Measurements were carried out on the forearm and finger of 20 healthy volunteers, using a blood pressure cuff on the upper arm to induce different levels of oxygenation. Repeatability of both devices was assessed, and the Bland–Altman method was used to assess agreement between them. The devices showed agreement in overall tracking of changes in SO2. Test–retest agreement for the Harrison device was worse than for O2C, with SD repeatability of 10.6% (forearm) or 18.6% (finger). There was no overall bias between devices, but mean (SD) difference of 1.2 (11.8%) (forearm) or 4.4 (11.5%) (finger) were outside of a clinically acceptable range. Disagreements were attributed to the stability of the Harrison probe and the natural SO2 variations across the skin surface increasing the random error. Therefore, though not equivalent to the LEA O2C, a probe redesign and averaged measurements may help establish the Harrison device as a low cost alternative. (paper)

  19. Noninvasive measurement of lower extremity muscle oxygen extraction fraction under cuff compression paradigm.

    Science.gov (United States)

    Wang, Chengyan; Zhang, Rui; Zhang, Xiaodong; Wang, He; Zhao, Kai; Jin, Lixin; Zhang, Jue; Wang, Xiaoying; Fang, Jing

    2016-05-01

    To demonstrate the feasibility of using a susceptibility-based MRI technique with asymmetric spin-echo (ASE) sequence to assess the lower extremity muscle oxygen extraction fraction (OEF) alternations under cuff compression paradigm. Approved by the local institutional human study committee, nine healthy young volunteers participated in this study. All the ASE scans were conducted using a 3 Tesla clinical MRI scanner during resting state (pre), 1-3 min (post1) and 3-5 min (post2) after a pressure of 50 mmHg above individual systolic blood pressure imposed on the thigh. Moreover, near-infrared spectroscopy (NIRS) measurements were performed on the same day under the same cuff compression protocol to verify the accuracy of this susceptibility-based method. In all volunteers, the mean MRI based OEF in gastrocnemius (GAS) muscle increased significantly from 0.28 ± 0.02 (pre) to 0.31 ± 0.03 (post1, P measured 1-%HbO2 (percentage of deoxyhemoglobin concentration within total hemoglobin) in GAS rose significantly from 0.29 ± 0.03 (pre) to 0.31 ± 0.04 (post1, P measuring skeletal muscle oxygenation. © 2015 Wiley Periodicals, Inc.

  20. Cerebral misery perfusion diagnosed using hypercapnic blood-oxygenation-level-dependent contrast functional magnetic resonance imaging: a case report

    Directory of Open Access Journals (Sweden)

    D'Souza Olympio

    2010-02-01

    Full Text Available Abstract Introduction Cerebral misery perfusion represents a failure of cerebral autoregulation. It is an important differential diagnosis in post-stroke patients presenting with collapses in the presence of haemodynamically significant cerebrovascular stenosis. This is particularly the case when cortical or internal watershed infarcts are present. When this condition occurs, further investigation should be done immediately. Case presentation A 50-year-old Caucasian man presented with a stroke secondary to complete occlusion of his left internal carotid artery. He went on to suffer recurrent seizures. Neuroimaging demonstrated numerous new watershed-territory cerebral infarcts. No source of arterial thromboembolism was demonstrable. Hypercapnic blood-oxygenation-level-dependent-contrast functional magnetic resonance imaging was used to measure his cerebrovascular reserve capacity. The findings were suggestive of cerebral misery perfusion. Conclusions Blood-oxygenation-level-dependent-contrast functional magnetic resonance imaging allows the inference of cerebral misery perfusion. This procedure is cheaper and more readily available than positron emission tomography imaging, which is the current gold standard diagnostic test. The most evaluated treatment for cerebral misery perfusion is extracranial-intracranial bypass. Although previous trials of this have been unfavourable, the results of new studies involving extracranial-intracranial bypass in high-risk patients identified during cerebral perfusion imaging are awaited. Cerebral misery perfusion is an important and under-recognized condition in which emerging imaging and treatment modalities present the possibility of practical and evidence-based management in the near future. Physicians should thus be aware of this disorder and of recent developments in diagnostic tests that allow its detection.

  1. Oscillometric blood pressure measurements: differences between measured and calculated mean arterial pressure.

    NARCIS (Netherlands)

    Kiers, H.D.; Hofstra, J.M.; Wetzels, J.F.M.

    2008-01-01

    Mean arterial pressure (MAP) is often used as an index of overall blood pressure. In recent years, the use of automated oscillometric blood pressure measurement devices is increasing. These devices directly measure and display MAP; however, MAP is often calculated from systolic blood pressure (SBP)

  2. Home blood pressure measurement in elderly patients with cognitive impairment: comparison of agreement between relative-measured blood pressure and automated blood pressure measurement.

    Science.gov (United States)

    Plichart, Matthieu; Seux, Marie-Laure; Caillard, Laure; Chaussade, Edouard; Vidal, Jean-Sébastien; Boully, Clémence; Hanon, Olivier

    2013-08-01

    Home blood pressure measurement (HBPM) is recommended by guidelines for hypertension management. However, this method might be difficult to use in elderly individuals with cognitive disorders. Our aim was to assess the agreement and the feasibility of HBPM by a relative as compared with 24-h ambulatory blood pressure monitoring (ABPM) in elderly patients with dementia. Sixty outpatients with dementia aged 75 years and older with office hypertension (≥140/90 mmHg) were subjected successively to HBPM by a trained relative and 24-h ABPM. The order of the two methods was randomized. Current guidelines' thresholds for the diagnosis of hypertension were used. The mean (SD) age of the patients was 80.8 (6.1) years (55% women) and the mean (SD) mini-mental state examination score was 20.1 (6.9). The feasibility of relative-HBPM was very high, with a 97% success rate (defined by ≥12/18 measurements reported). The blood pressure measurements were highly correlated between the two methods (r=0.75 and 0.64 for systolic blood pressure and diastolic blood pressure, respectively; Pmethods for the diagnosis of sustained hypertension and white-coat hypertension was excellent (overall agreement, 92%; κ coefficient, 0.81; 95% CI, 0.61-0.93). Similar results were found for daytime-ABPM. In cognitively impaired elderly patients, HBPM by a relative using an automated device was a good alternative to 24-h ABPM.

  3. Correlation between single-trial visual evoked potentials and the blood oxygenation level dependent response in simultaneously recorded electroencephalography-functional magnetic resonance imaging

    DEFF Research Database (Denmark)

    Fuglø, Dan; Pedersen, Henrik; Rostrup, Egill

    2012-01-01

    in different occipital and extraoccipital cortical areas not explained by the boxcar regressor. The results suggest that the P1-N2 regressor is the best EEG-based regressor to model the visual paradigm, but when looking for additional effects like habituation or attention modulation that cannot be modeled......To compare different electroencephalography (EEG)-based regressors and their ability to predict the simultaneously recorded blood oxygenation level dependent response during blocked visual stimulation, simultaneous EEG-functional magnetic resonance imaging in 10 healthy volunteers was performed....... The performance of different single-trial EEG regressors was compared in terms of predicting the measured blood oxygenation level dependent response. The EEG-based regressors were the amplitude and latency of the primary positive (P1) and negative (N2) peaks of the visual evoked potential, the combined P1-N2...

  4. Effects of blood transfusion on oxygen extraction ratio and central venous saturation in children after cardiac surgery.

    Science.gov (United States)

    Nasser, Bana; Tageldein, Mohmad; AlMesned, Abdulrahman; Kabbani, Mohammad

    2017-01-01

    Red blood cell transfusion is common in critically ill children after cardiac surgery. Since the threshold for hemoglobin (Hb) transfusion need is not well defined, the threshold Hb level at which dependent critical oxygen uptake-to-delivery (VO2-DO2) status compensation is uncertain. To assess the effects of blood transfusion on the oxygen extraction ratio (O2ER) and central venous oxygen saturation (ScvO2) to identify a critical O2ER value that could help us determine the critical need for blood transfusion. Prospective, observational cohort study. Cardiac Surgical Intensive Care Unit at Prince Sultan Cardiac Center in Qassim, Saudi Arabia. Between January 2013 and December 2015, we included all children with cardiac disease who underwent surgery and needed a blood transfusion. Demographic and laboratory data with physiological parameters before and 1 and 6 hours after transfusion were recorded and O2ER before and 6 hours after transfusion was computed. Cases were divided into two groups based on O2ER: Patients with increased O2ER (O2ER > 40%) and normal patients without increased O2ER (O2ER transfusion. Changes in O2ER and ScvO2 following blood transfusion. Of 103 patients who had blood transfusion, 75 cases had normal O2ER before transfusion while 28 cases had increased O2ER before transfusion. Following blood transfusion, O2ER and ScvO2 improved in the group that had increased O2ER before transfusion, but not in the group that had normal O2ER before transfusion. The clinical and hemodynamic indicators O2ER and ScvO2 may be considered as markers that can indicate a need for blood transfusion. The limitation of this study is the small number of patients that had increased O2ER before transfusion. There were few available variables to assess oxygen consumption.

  5. Experiment to measure oxygen opacity at high density and temperature

    Science.gov (United States)

    Keiter, Paul; Butler, Hannah; Trantham, Matt; Mussack, Katie; Colgan, James; Fontes, Chris; Guzik, Joyce; Kilcrease, David; Perry, Ted; Orban, Chris; Ducret, Jean-Eric; La Pennec, Maelle; Turck-Chieze, Sylvaine; Mancini, Roberto; Heeter, Robert

    2017-10-01

    In recent years, there has been a debate over the abundances of heavy elements (Z >2) in the solar interior. Recent solar atmosphere models [Asplund 2009] find a significantly lower abundance for C, N, and O compared to models used roughly a decade ago. Recent opacity measurements of iron disagree with opacity model predictions [Bailey et al., 2015]. Repeated scrutiny of the experiment and data has not produced a conclusive reason for the discrepancy. New models have been implemented in the ATOMIC opacity code for low-Z elements [Colgan, 2013, Armstrong 2014], however no data currently exists to test the low-Z material models in the regime relevant to the solar convection zone. We present an experimental design using the opacity platform developed at the National Ignition Facility to study the oxygen opacity at densities and temperatures near the solar convection zone conditions. This work is funded by the U.S. DOE, through the NNSA-DS and SC-OFES Joint Program in HEDLP, Grant Number DE-NA0002956, and the NLUF Program, Grant Number DE-NA0002719, and through the LLE, University of Rochester by the NNSA/OICF under No. DE-NA0001944.

  6. ASRDI oxygen technology survey. Volume 5: Density and liquid level measurement instrumentation for the cryogenic fluids oxygen, hydrogen, and nitrogen

    Science.gov (United States)

    Roder, H. M.

    1974-01-01

    Information is presented on instrumentation for density measurement, liquid level measurement, quantity gauging, and phase measurement. Coverage of existing information directly concerned with oxygen was given primary emphasis. A description of the physical principle of measurement for each instrumentation type is included. The basic materials of construction are listed if available from the source document for each instrument discussed. Cleaning requirements, procedures, and verification techniques are included.

  7. Extraction of water labeled with oxygen 15 during single-capillary transit. Influence of blood pressure, osmolarity, and blood-brain barrier damage

    International Nuclear Information System (INIS)

    Go, K.G.; Lammertsma, A.A.; Paans, A.M.; Vaalburg, W.; Woldring, M.G.

    1981-01-01

    By external detection, the influence of arterial blood pressure (BP), osmolarity, and cold-induced blood-brain barrier damage was assessed on the extraction of water labeled with oxygen 15 during single-capillary transit in the rat. There was an inverse relation between arterial BP and extraction that was attributable to the influence of arterial BP on cerebral blood flow (CBF) and the relation between CBF and extraction. Neither arterial BP nor osmolarity of the injected bolus had any direct effect on extraction of water 15O, signifying that the diffusional exchange component (determined by blood flow) of extraction greatly surpasses the convection flow contribution by hydrostatic or osmotic forces. Damage to the blood-brain barrier did not change its permeability to water

  8. Removal of cellular-type hemoglobin-based oxygen carrier (hemoglobin-vesicles) from blood using centrifugation and ultrafiltration.

    Science.gov (United States)

    Sakai, Hiromi; Sou, Keitaro; Horinouchi, Hirohisa; Tsuchida, Eishun; Kobayashi, Koichi

    2012-02-01

    The hemoglobin-vesicle (HbV) is an artificial oxygen carrier encapsulating a concentrated hemoglobin solution in a phospholipid vesicle (liposome). During or after transporting oxygen, macrophages capture HbVs in the reticuloendothelial system (RES) with an approximate circulation half-life of 3 days. Animal studies show transient splenohepatomegaly after large doses, but HbVs were completely degraded, and the components were excreted in a few weeks. If a blood substitute is used for emergency use until red blood cell transfusion becomes available or for temporary use such as a priming fluid for an extracorporeal circuit, then one option would be to remove HbVs from the circulating blood without waiting a few weeks for removal by the RES. Using a mixture of beagle dog whole blood and HbV, we tested the separation of HbV using a centrifugal Fresenius cell separator and an ultrafiltration system. The cell separator system separated the layers of blood cell components from the HbV-containing plasma layer by centrifugal force, and then the HbV was removed from plasma phase by the ultrafiltration system. The HbVs (250-280 nm) are larger than plasma proteins (blood cell components (> 3 µm). The size of HbVs is advantageous to be separated from the original blood components, and the separated blood components can be returned to circulation. © 2011, Copyright the Authors. Artificial Organs © 2011, International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

  9. Blood pressure measurements in the ankle are not equivalent to ...

    African Journals Online (AJOL)

    Background. Blood pressure (BP) is often measured on the ankle in the emergency department (ED), but this has never been shown to be an acceptable alternative to measurements performed on the arm. Objective. To establish whether the differences between arm and ankle non-invasive BP measurements were clinically ...

  10. Blood lipid measurements. Variations and practical utility.

    Science.gov (United States)

    Cooper, G R; Myers, G L; Smith, S J; Schlant, R C

    1992-03-25

    To describe the magnitude and impact of the major biological and analytical sources of variation in serum lipid and lipoprotein levels on risk of coronary heart disease; to present a way to qualitatively estimate the total intraindividual variation; and to demonstrate how to determine the number of specimens required to estimate, with 95% confidence, the "true" underlying total cholesterol value in the serum of a patient. Representative references on each source of variation were selected from more than 300 reviewed publications, most published within the past 5 years, to document current findings and concepts. Most articles reviewed were in English. Studies on biological sources of variation were selected using the following criteria: representative of published findings, clear statement of either significant or insignificant results, and acquisition of clinical and laboratory data under standardized conditions. Representative results for special populations such as women and children are reported when results differ from those of adult men. References were selected based on acceptable experimental design and use of standardized laboratory lipid measurements. The lipid levels considered representative for a selected source of variation arose from quantitative measurements by a suitably standardized laboratory. Statistical analysis of data was examined to assure reliability. The proposed method of estimating the biological coefficient of variation must be considered to give qualitative results, because only two or three serial specimens are collected in most cases for the estimation. Concern has arisen about the magnitude, impact, and interpretation of preanalytical as well as analytical sources of variation on reported results of lipid measurements of an individual. Preanalytical sources of variation from behavioral, clinical, and sampling sources constitute about 60% of the total variation in a reported lipid measurement of an individual. A technique is presented

  11. Oxygen deficiency at CERN: Hazards, risks & mitigation measures

    CERN Multimedia

    CERN. Geneva

    2016-01-01

    Compressed and liquified gases are used at many places at CERN. If they are introduced to the atmosphere, they can present an oxygen deficiency hazard (ODH) and lead to reduced abilities, unconsciousness or even death. The CERN method for ODH risk assessments is done on a case-by-case basis as each situation is unique. It is crucial to make sure the personnel can evacuate safely in case of an ODH situation. My talk will explain human reactions to reduced oxygen levels and I will give some practical examples on how one can assess and control the hazards from a possible oxygen deficient atmosphere. Some real accidents involving oxygen deficiency will also be mentioned.

  12. Comparison of ambulatory blood pressure monitoring and office blood pressure measurements in obese children and adolescents.

    Science.gov (United States)

    Renda, Rahime

    2018-04-01

    Obesity in adults has been related to hypertension and abnormal nocturnal dipping of blood pressure, which are associated with poor cardiovascular and renal outcomes. Here, we aimed to resolve the relationship between the degree of obesity, the severity of hypertension and dipping status on ambulatory blood pressure in obese children. A total 72 patients with primary obesity aged 7 to 18 years (mean: 13.48 ± 3.25) were selected. Patients were divided into three groups based on body mass index (BMİ) Z-score. Diagnosis and staging of ambulatory hypertension based on 24-h blood pressure measurements, obtained from ambulatory blood pressure monitoring. Based on our ambulatory blood pressure data, 35 patients (48.6%) had hypertension, 7 (20%) had ambulatory prehypertension, 21 (60%) had hypertension, and 7 patients (20%) had severe ambulatory hypertension. There was a significant relationship between severity of hypertension and the degree of obesity (p lood pressure results and loads were similar between groups. Diastolic and mean arterial blood pressure levels during the night, diastolic blood pressure loads, and heart rate during the day were significantly higher in Group 3 (p lood pressure at night, mean arterial pressure at night, diastolic blood pressure loads and heart rate at day. Increase in BMI Z-score does not a significant impact on daytime blood pressure and nocturnal dipping status.

  13. Volume-dependent K+ transport in rabbit red blood cells comparison with oxygenated human SS cells

    Energy Technology Data Exchange (ETDEWEB)

    Al-Rohil, N.; Jennings, M.L.

    1989-07-01

    In this study the volume-dependent or N-ethylmaleimide (NEM)-stimulated, ouabain-insensitive K+ influx and efflux were measured with the tracer 86Rb+ in rabbit red blood cells. The purpose of the work was to examine the rabbit as a potential model for cell volume regulation in human SS red blood cells and also to investigate the relationship between the NEM-reactive sulfhydryl group(s) and the signal by which cell swelling activates the transport. Ouabain-resistant K+ efflux and influx increase nearly threefold in cells swollen hypotonically by 15%. Pretreatment with 2 mM NEM stimulates efflux 5-fold and influx 10-fold (each measured in an isotonic medium). The ouabain-resistant K+ efflux was dependent on the major anion in the medium. The anion dependence of K+ efflux in swollen or NEM-stimulated cells was as follows: Br- greater than Cl- much greater than NO3- = acetate. The magnitudes of both the swelling- and the NEM-stimulated fluxes are much higher in young cells (density separated but excluding reticulocytes) than in older cells. Swelling- or NEM-stimulated K+ efflux in rabbit red blood cells was inhibited 50% by 1 mM furosemide, and the inhibitory potency of furosemide was enhanced by extracellular K+, as is known to be true for human AA and low-K+ sheep red blood cells. The swelling-stimulated flux in both rabbit and human SS cells has a pH optimum at approximately 7.4. We conclude that rabbit red blood cells are a good model for swelling-stimulated K+ transport in human SS cells.

  14. Effects of zilpaterol hydrochloride on methane production, total body oxygen consumption, and blood metabolites in finishing beef steers

    Science.gov (United States)

    An indirect calorimetry experiment was conducted to determine the effects of feeding zilpaterol hydrochloride (ZH) for 20 d on total body oxygen consumption, respiratory quotient, methane production, and blood metabolites in finishing beef steers. Sixteen Angus steers (initial BW = 555 ± 12.7 kg) w...

  15. Rejuvenation of stored human red blood cells reverses the renal microvascular oxygenation deficit in an isovolemic transfusion model in rats

    NARCIS (Netherlands)

    Raat, Nicolaas J. H.; Hilarius, Petra M.; Johannes, Tanja; de Korte, Dirk; Ince, Can; Verhoeven, Arthur J.

    2009-01-01

    BACKGROUND: Storage of red blood cells (RBCs) results in various biochemical changes, including a decrease in cellular adenosine triphosphate and 2,3-diphosphoglycerate acid. Previously it was shown that stored human RBCs show a deficit in the oxygenation of the microcirculation in the gut of

  16. Contribution of blood oxygen and carbon dioxide sensing to the energetic optimization of human walking.

    Science.gov (United States)

    Wong, Jeremy D; O'Connor, Shawn M; Selinger, Jessica C; Donelan, J Maxwell

    2017-08-01

    People can adapt their gait to minimize energetic cost, indicating that walking's neural control has access to ongoing measurements of the body's energy use. In this study we tested the hypothesis that an important source of energetic cost measurements arises from blood gas receptors that are sensitive to O 2 and CO 2 concentrations. These receptors are known to play a role in regulating other physiological processes related to energy consumption, such as ventilation rate. Given the role of O 2 and CO 2 in oxidative metabolism, sensing their levels can provide an accurate estimate of the body's total energy use. To test our hypothesis, we simulated an added energetic cost for blood gas receptors that depended on a subject's step frequency and determined if subjects changed their behavior in response to this simulated cost. These energetic costs were simulated by controlling inspired gas concentrations to decrease the circulating levels of O 2 and increase CO 2 We found this blood gas control to be effective at shifting the step frequency that minimized the ventilation rate and perceived exertion away from the normally preferred frequency, indicating that these receptors provide the nervous system with strong physiological and psychological signals. However, rather than adapt their preferred step frequency toward these lower simulated costs, subjects persevered at their normally preferred frequency even after extensive experience with the new simulated costs. These results suggest that blood gas receptors play a negligible role in sensing energetic cost for the purpose of optimizing gait. NEW & NOTEWORTHY Human gait adaptation implies that the nervous system senses energetic cost, yet this signal is unknown. We tested the hypothesis that the blood gas receptors sense cost for gait optimization by controlling blood O 2 and CO 2 with step frequency as people walked. At the simulated energetic minimum, ventilation and perceived exertion were lowest, yet subjects

  17. Aortic blood flow subtraction: an alternative method for measuring total renal blood flow in conscious dogs

    DEFF Research Database (Denmark)

    Sandgaard, N C F; Andersen, J L; Holstein-Rathlou, N-H

    2002-01-01

    We have measured total renal blood flow (TRBF) as the difference between signals from ultrasound flow probes implanted around the aorta above and below the renal arteries. The repeatability of the method was investigated by repeated, continuous infusions of angiotensin II and endothelin-1 seven...... arterial blood pressure by 49% and decreased TRBF by 12%, providing an increase in renal vascular resistance of 69%. Dynamic analysis showed autoregulation of renal blood flow in the frequency range ... of TRBF by aortic blood flow subtraction is a practical and reliable method that allows direct comparison of excretory function and renal blood flow from two kidneys. The method also allows direct comparison between TRBF and flow in the caudal aorta....

  18. Myocardial Blood Volume Is Associated with Myocardial Oxygen Consumption: An Experimental Study with CMR in a Canine Model

    Science.gov (United States)

    McCommis, Kyle S.; Zhang, Haosen; Goldstein, Thomas A.; Misselwitz, Bernd; Abendschein, Dana R.; Gropler, Robert J.; Zheng, Jie

    2009-01-01

    OBJECTIVES To evaluate the feasibility of cardiovascular MR (CMR) to determine regional myocardial perfusion and O2 metabolism, and assess the role of myocardial blood volume (MBV) on oxygen supply. BACKGROUND Coronary artery disease presents as an imbalance of myocardial oxygen supply and demand. We have developed relevant CMR methods to determine the relationship of myocardial blood flow (MBF) and MBV to oxygen consumption (MVO2) during pharmacologic hyperemia. METHODS Twenty-one mongrel dogs were studied with varying stenosis severities imposed on the proximal left anterior descending (LAD) coronary artery. MBF and MBV were determined by CMR first-pass perfusion, while the oxygen extraction fraction (OEF) and MVO2 were determined by the myocardial Blood-Oxygen-Level-Dependent (BOLD) effect and Fick’s law, respectively. MR imaging was performed at rest, and during either dipyridamole-induced vasodilation or dobutamine-induced hyperemia. Regional differences in myocardial perfusion and oxygenation were then evaluated. RESULTS Dipyridamole and dobutamine both led to 145–200% increases in MBF and 50–80% increases in MBV in normal perfused myocardium. As expected, MVO2 increased more significantly with dobutamine (~175%) than dipyridamole (~40%). Coronary stenosis resulted in an attenuation of MBF, MBV, and MVO2 in both the LAD-subtended stenosis region and the left circumflex subtended remote region. Liner regression analysis showed that MBV reserve appears to be more correlated with MVO2 reserve during dobutamine stress than MBF reserve, particularly in the stenotic regions. Conversely, MBF reserve appears to be more correlated with MVO2 reserve during dipyridamole, although neither of these differences was significant. CONCLUSIONS Noninvasive evaluation of both myocardial perfusion and oxygenation by CMR facilitates direct monitoring of regional myocardial ischemia and provides a valuable tool for better understanding microvascular pathophysiology. These

  19. Regional blood flow distribution and oxygen metabolism during mesenteric ischemia and congestion.

    Science.gov (United States)

    Cruz, Ruy J; Garrido, Alejandra G; Ribeiro, Cristiane M F; Harada, Tomoyuki; Rocha-e-Silva, Mauricio

    2010-06-01

    Acute mesenteric ischemia is a potentially fatal vascular emergency with mortality rates ranging between 60% and 80%. Several studies have extensively examined the hemodynamic and metabolic effects of superior mesenteric artery occlusion. On the other hand, the cardiocirculatory derangement and the tissue damage induced by intestinal outflow obstruction have not been investigated systematically. For these reasons we decided to assess the initial impact of venous mesenteric occlusion on intestinal blood flow distribution, and correlate these findings with other systemic and regional perfusion markers. Fourteen mongrel dogs were subjected to 45 min of superior mesenteric artery (SMAO) or vein occlusion (SMVO), and observed for 120 min after reperfusion. Systemic hemodynamics were evaluated using Swan-Ganz and arterial catheters. Regional blood flow (ultrasonic flow probes), intestinal O(2)-derived variables, and mesenteric-arterial and tonometric-arterial pCO(2) gradients (D(mv-a)pCO(2) and D(t-a)pCO(2)) were also calculated. SMVO was associated with hypotension and low cardiac output. A significant increase in the regional pCO(2) gradients was also observed in both groups during the ischemic period. After reperfusion, a progressive reduction in D(mv-a)pCO(2) occurred in the SMVO group; however, no improvement in D(t-a)pCO(2) was observed. The histopathologic injury scores were 2.7 +/- 0.5 and 4.8 +/- 0.2 for SMAO and SMVO, respectively. SMV occlusion promoted early and significant hemodynamic and metabolic derangement at systemic and regional levels. Additionally, systemic pCO(2) gradient is not a reliable parameter to evaluate the local intestinal oxygenation. Finally, the D(t-a)pCO(2) correlates with histologic changes during intestinal congestion or ischemia. However, minor histologic changes cannot be detected using this methodology. Copyright (c) 2010 Elsevier Inc. All rights reserved.

  20. Effects of the Oxygen-Carrying Solution OxyVita C on the Cerebral Microcirculation and Systemic Blood Pressures in Healthy Rats

    Directory of Open Access Journals (Sweden)

    Rania Abutarboush

    2014-11-01

    Full Text Available The use of hemoglobin-based oxygen carriers (HBOC as oxygen delivering therapies during hypoxic states has been hindered by vasoconstrictive side effects caused by depletion of nitric oxide (NO. OxyVita C is a promising oxygen-carrying solution that consists of a zero-linked hemoglobin polymer with a high molecular weight (~17 MDa. The large molecular weight is believed to prevent extravasation and limit NO scavenging and vasoconstriction. The aim of this study was to assess vasoactive effects of OxyVita C on systemic blood pressures and cerebral pial arteriole diameters. Anesthetized healthy rats received four intravenous (IV infusions of an increasing dose of OxyVita C (2, 25, 50, 100 mg/kg and hemodynamic parameters and pial arteriolar diameters were measured pre- and post-infusion. Normal saline was used as a volume-matched control. Systemic blood pressures increased (P ≤ 0.05 with increasing doses of OxyVita C, but not with saline. There was no vasoconstriction in small (<50 µm and medium-sized (50–100 µm pial arterioles in the OxyVita C group. In contrast, small and medium-sized pial arterioles vasoconstricted in the control group. Compared to saline, OxyVita C showed no cerebral vasoconstriction after any of the four doses evaluated in this rat model despite increases in blood pressure.

  1. Cerebral oxygenation in the beach chair position for shoulder surgery in regional anesthesia: impact on cerebral blood flow and neurobehavioral outcome.

    Science.gov (United States)

    Aguirre, José A; Märzendorfer, Olivia; Brada, Muriel; Saporito, Andrea; Borgeat, Alain; Bühler, Philipp

    2016-12-01

    Beach chair position is considered a potential risk factor for central neurological events particularly if combined with low blood pressure. The aim of this study was to assess the impact of regional anesthesia on cerebral blood flow and neurobehavioral outcome. This is a prospective, assessor-blinded observational study evaluating patients in the beach chair position undergoing shoulder surgery under regional anesthesia. University hospital operating room. Forty patients with American Society of Anesthesiologists classes I-II physical status scheduled for elective shoulder surgery. Cerebral saturation and blood flow of the middle cerebral artery were measured prior to anesthesia and continued after beach chair positioning until discharge to the postanesthesia care unit. The anesthesiologist was blinded for these values. Controlled hypotension with systolic blood pressure≤100mm Hg was maintained during surgery. Neurobehavioral tests and values of regional cerebral saturation, bispectral index, the mean maximal blood flow of the middle cerebral artery, and invasive blood pressure were measured prior to regional anesthesia, and measurements were repeated after placement of the patient on the beach chair position and every 20 minutes thereafter until discharge to postanesthesia care unit. The neurobehavioral tests were repeated the day after surgery. The incidence of cerebral desaturation events was 5%. All patients had a significant blood pressure drop 5 minutes after beach chair positioning, measured at the heart as well as the acoustic meatus levels, when compared with baseline values (Psurgery (Pshoulder surgery had no major impact on cerebral blood flow and cerebral oxygenation. However, some impact on neurobehavioral outcome 24 hours after surgery was observed. Copyright © 2016 Elsevier Inc. All rights reserved.

  2. The role of tissue oxygen tension in the control of local blood flow in the microcirculation of skeletal muscles

    DEFF Research Database (Denmark)

    Ngo, Thuc Anh

    2010-01-01

    In the microcirculation blood flow is highly regulated dependent on the metabolic activity of the tissues. Among several mechanisms, mechanisms involved in the coupling of changes in tissue oxygen tension due to changes in the metabolic activity of the tissue play an important role. In the systemic...... (inhibitor of KATP channels) in the superfusate abolished both vasodilatation and constriction to low and high oxygen superfusate, indicating that KATP channels are involved in both hypoxic vasodilatation and hyperoxic vasoconstriction. Red blood cells (RBCs) have been proposed to release ATP and...... as in the intact blood-perfused arteriole. This indicates that RBCs are not essential for hypoxic vasodilatation. In addition several potential pathways were evaluated. Application of DPCPX (inhibitor of adenosine A1 and A2 receptors) and L-NAME (inhibitor of NO-synthase) did not affect vasomotor responses to low...

  3. Establishing traceability of photometric absorbance values for accurate measurements of the haemoglobin concentration in blood

    Science.gov (United States)

    Witt, K.; Wolf, H. U.; Heuck, C.; Kammel, M.; Kummrow, A.; Neukammer, J.

    2013-10-01

    Haemoglobin concentration in blood is one of the most frequently measured analytes in laboratory medicine. Reference and routine methods for the determination of the haemoglobin concentration in blood are based on the conversion of haeme, haemoglobin and haemiglobin species into uniform end products. The total haemoglobin concentration in blood is measured using the absorbance of the reaction products. Traceable absorbance measurement values on the highest metrological level are a prerequisite for the calibration and evaluation of procedures with respect to their suitability for routine measurements and their potential as reference measurement procedures. For this purpose, we describe a procedure to establish traceability of spectral absorbance measurements for the haemiglobincyanide (HiCN) method and for the alkaline haematin detergent (AHD) method. The latter is characterized by a higher stability of the reaction product. In addition, the toxic hazard of cyanide, which binds to the iron ion of the haem group and thus inhibits the oxygen transport, is avoided. Traceability is established at different wavelengths by applying total least-squares analysis to derive the conventional quantity values for the absorbance from the measured values. Extrapolation and interpolation are applied to get access to the spectral regions required to characterize the Q-absorption bands of the HiCN and AHD methods, respectively. For absorbance values between 0.3 and 1.8, the contributions of absorbance measurements to the total expanded uncertainties (95% level of confidence) of absorbance measurements range from 1% to 0.4%.

  4. Noninvasive measurement of an index of renal blood flow

    International Nuclear Information System (INIS)

    Powers, T.A.; Rees, R.S.; Bowen, R.D.

    1983-01-01

    A new technique for the noninvasive measurement of an index of renal blood flow is described. The method utilizes ultrasound determined renal volume and radionuclide assessment of the mean transit time of a pertechnetate bolus through the kidneys. From this information a value for flow is calculated according to compartmental analysis principles. There is good correlation between renal blood flow estimated by this technique and that determined by microsphere injection

  5. Automatic noninvasive measurement of systolic blood pressure using photoplethysmography

    Directory of Open Access Journals (Sweden)

    Glik Zehava

    2009-10-01

    Full Text Available Abstract Background Automatic measurement of arterial blood pressure is important, but the available commercial automatic blood pressure meters, mostly based on oscillometry, are of low accuracy. Methods In this study, we present a cuff-based technique for automatic measurement of systolic blood pressure, based on photoplethysmographic signals measured simultaneously in fingers of both hands. After inflating the pressure cuff to a level above systolic blood pressure in a relatively slow rate, it is slowly deflated. The cuff pressure for which the photoplethysmographic signal reappeared during the deflation of the pressure-cuff was taken as the systolic blood pressure. The algorithm for the detection of the photoplethysmographic signal involves: (1 determination of the time-segments in which the photoplethysmographic signal distal to the cuff is expected to appear, utilizing the photoplethysmographic signal in the free hand, and (2 discrimination between random fluctuations and photoplethysmographic pattern. The detected pulses in the time-segments were identified as photoplethysmographic pulses if they met two criteria, based on the pulse waveform and on the correlation between the signal in each segment and the signal in the two neighboring segments. Results Comparison of the photoplethysmographic-based automatic technique to sphygmomanometry, the reference standard, shows that the standard deviation of their differences was 3.7 mmHg. For subjects with systolic blood pressure above 130 mmHg the standard deviation was even lower, 2.9 mmHg. These values are much lower than the 8 mmHg value imposed by AAMI standard for automatic blood pressure meters. Conclusion The photoplethysmographic-based technique for automatic measurement of systolic blood pressure, and the algorithm which was presented in this study, seems to be accurate.

  6. Estimating the measurement uncertainty in forensic blood alcohol analysis.

    Science.gov (United States)

    Gullberg, Rod G

    2012-04-01

    For many reasons, forensic toxicologists are being asked to determine and report their measurement uncertainty in blood alcohol analysis. While understood conceptually, the elements and computations involved in determining measurement uncertainty are generally foreign to most forensic toxicologists. Several established and well-documented methods are available to determine and report the uncertainty in blood alcohol measurement. A straightforward bottom-up approach is presented that includes: (1) specifying the measurand, (2) identifying the major components of uncertainty, (3) quantifying the components, (4) statistically combining the components and (5) reporting the results. A hypothetical example is presented that employs reasonable estimates for forensic blood alcohol analysis assuming headspace gas chromatography. These computations are easily employed in spreadsheet programs as well. Determining and reporting measurement uncertainty is an important element in establishing fitness-for-purpose. Indeed, the demand for such computations and information from the forensic toxicologist will continue to increase.

  7. The Not-So-Global Blood Oxygen Level-Dependent Signal.

    Science.gov (United States)

    Billings, Jacob; Keilholz, Shella

    2018-04-01

    Global signal regression is a controversial processing step for resting-state functional magnetic resonance imaging, partly because the source of the global blood oxygen level-dependent (BOLD) signal remains unclear. On the one hand, nuisance factors such as motion can readily introduce coherent BOLD changes across the whole brain. On the other hand, the global signal has been linked to neural activity and vigilance levels, suggesting that it contains important neurophysiological information and should not be discarded. Any widespread pattern of coordinated activity is likely to contribute appreciably to the global signal. Such patterns may include large-scale quasiperiodic spatiotemporal patterns, known also to be tied to performance on vigilance tasks. This uncertainty surrounding the separability of the global BOLD signal from concurrent neurological processes motivated an examination of the global BOLD signal's spatial distribution. The results clarify that although the global signal collects information from all tissue classes, a diverse subset of the BOLD signal's independent components contribute the most to the global signal. Further, the timing of each network's contribution to the global signal is not consistent across volunteers, confirming the independence of a constituent process that comprises the global signal.

  8. Complexity of low-frequency blood oxygen level-dependent fluctuations covaries with local connectivity.

    Science.gov (United States)

    Anderson, Jeffrey S; Zielinski, Brandon A; Nielsen, Jared A; Ferguson, Michael A

    2014-04-01

    Very low-frequency blood oxygen level-dependent (BOLD) fluctuations have emerged as a valuable tool for describing brain anatomy, neuropathology, and development. Such fluctuations exhibit power law frequency dynamics, with largest amplitude at lowest frequencies. The biophysical mechanisms generating such fluctuations are poorly understood. Using publicly available data from 1,019 subjects of age 7-30, we show that BOLD fluctuations exhibit temporal complexity that is linearly related to local connectivity (regional homogeneity), consistently and significantly covarying across subjects and across gray matter regions. This relationship persisted independently of covariance with gray matter density or standard deviation of BOLD signal. During late neurodevelopment, BOLD fluctuations were unchanged with age in association cortex while becoming more random throughout the rest of the brain. These data suggest that local interconnectivity may play a key role in establishing the complexity of low-frequency BOLD fluctuations underlying functional magnetic resonance imaging connectivity. Stable low-frequency power dynamics may emerge through segmentation and integration of connectivity during development of distributed large-scale brain networks. Copyright © 2013 Wiley Periodicals, Inc.

  9. Cerebrovascular blood oxygenation level dependent pulsatility at baseline and following acute exercise among healthy adolescents.

    Science.gov (United States)

    Theyers, Athena E; Goldstein, Benjamin I; Metcalfe, Arron Ws; Robertson, Andrew D; MacIntosh, Bradley J

    2018-01-01

    Arterial stiffness is linked to cerebral small vessel damage and neurodegeneration, but barriers to accessing deep cerebrovascular anatomy limit our ability to assess the brain. This study describes an adaptation of a cardiac-related scrubbing method as a means of generating blood oxygenation level-dependent pulsatility maps based on the cardiac cycle. We examine BOLD pulsatility at rest, based on the non-parametric deviation from null metric, as well as changes following acute physiological stress from 20 min of moderate-intensity cycling in 45 healthy adolescents. We evaluate the influence of repetition time (TR) and echo time (TE) using simulated and multi-echo empirical data, respectively. There were tissue-specific and voxel-wise BOLD pulsatility decreases 20 min following exercise cessation. BOLD pulsatility detection was comparable over a range of TR and TE values when scan volumes were kept constant; however, short TRs (≤500 ms) and TEs (∼14 ms) acquisitions would yield the most efficient detection. Results suggest cardiac-related BOLD pulsatility may represent a robust and easily adopted method of mapping cerebrovascular pulsatility with voxel-wise resolution.

  10. Long term high flow humidified oxygen treatment in COPD – effect on blood gases

    DEFF Research Database (Denmark)

    Storgaard, Line; Weinreich, Ulla; Hockey, Hans

    2017-01-01

    .Aim: To investigate the treatment effect on arterial blood gases (PaO2, PaCO2 and SaO2) in patients with resting hypoxemia over 12 months.Method: In this prospective, randomized controlled, one-year study, 200 COPD patients treated with LTOT, all GOLD class 4, were randomized to NHF (n=100) or usual care (n=100......) between March 2013 and June 2015.Results: The groups are comparable in average days in study, age, gender, smoking status, pack years, BMI, FEV1%, 6 minutes walking test, administered oxygen (L/min), PaO2 PaCO2 and Sa02 at baseline and number of exacerbations and admissions one year prior to study start....... Treated with a mean NHF-flow of 20 L/min, no significant difference was seen in PaO2 or SaO2 over the study, but a significantly different change in PaCO2 was seen after 6 months (p<0.05) and after 12 months (p<0.01) in favor of patients treated with NHF. Increase in PaCO<2 was approximately 0...

  11. Blood oxygen-level dependent functional assessment of cerebrovascular reactivity: Feasibility for intraoperative 3 Tesla MRI.

    Science.gov (United States)

    Fierstra, Jorn; Burkhardt, Jan-Karl; van Niftrik, Christiaan Hendrik Bas; Piccirelli, Marco; Pangalu, Athina; Kocian, Roman; Neidert, Marian Christoph; Valavanis, Antonios; Regli, Luca; Bozinov, Oliver

    2017-02-01

    To assess the feasibility of functional blood oxygen-level dependent (BOLD) MRI to evaluate intraoperative cerebrovascular reactivity (CVR) at 3 Tesla field strength. Ten consecutive neurosurgical subjects scheduled for a clinical intraoperative MRI examination were enrolled in this study. In addition to the clinical protocol a BOLD sequence was implemented with three cycles of 44 s apnea to calculate CVR values on a voxel-by-voxel basis throughout the brain. The CVR range was then color-coded and superimposed on an anatomical volume to create high spatial resolution CVR maps. Ten subjects (mean age 34.8 ± 13.4; 2 females) uneventfully underwent the intraoperative BOLD protocol, with no complications occurring. Whole-brain CVR for all subjects was (mean ± SD) 0.69 ± 0.42, whereas CVR was markedly higher for tumor subjects as compared to vascular subjects, 0.81 ± 0.44 versus 0.33 ± 0.10, respectively. Furthermore, color-coded functional maps could be robustly interpreted for a whole-brain assessment of CVR. We demonstrate that intraoperative BOLD MRI is feasible in creating functional maps to assess cerebrovascular reactivity throughout the brain in subjects undergoing a neurosurgical procedure. Magn Reson Med 77:806-813, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.

  12. Multi frequency phase fluorimetry (MFPF) for oxygen partial pressure measurement: ex vivo validation by polarographic clark-type electrode.

    Science.gov (United States)

    Boehme, Stefan; Duenges, Bastian; Klein, Klaus U; Hartwich, Volker; Mayr, Beate; Consiglio, Jolanda; Baumgardner, James E; Markstaller, Klaus; Basciani, Reto; Vogt, Andreas

    2013-01-01

    Measurement of partial pressure of oxygen (PO2) at high temporal resolution remains a technological challenge. This study introduces a novel PO2 sensing technology based on Multi-Frequency Phase Fluorimetry (MFPF). The aim was to validate MFPF against polarographic Clark-type electrode (CTE) PO2 measurements. MFPF technology was first investigated in N = 8 anaesthetised pigs at FIO2 of 0.21, 0.4, 0.6, 0.8 and 1.0. At each FIO2 level, blood samples were withdrawn and PO2 was measured in vitro with MFPF using two FOXY-AL300 probes immediately followed by CTE measurement. Secondly, MFPF-PO2 readings were compared to CTE in an artificial circulatory setup (human packed red blood cells, haematocrit of 30%). The impacts of temperature (20, 30, 40°C) and blood flow (0.8, 1.6, 2.4, 3.2, 4.0 L min(-1)) on MFPF-PO2 measurements were assessed. MFPF response time in the gas- and blood-phase was determined. Porcine MFPF-PO2 ranged from 63 to 749 mmHg; the corresponding CTE samples from 43 to 712 mmHg. Linear regression: CTE = 15.59+1.18*MFPF (R(2) = 0.93; P0.05). MFPF response-time (monoexponential) was 1.48±0.26 s for the gas-phase and 1.51±0.20 s for the blood-phase. MFPF-derived PO2 readings were reproducible and showed excellent correlation and good agreement with Clark-type electrode-based PO2 measurements. There was no relevant impact of temperature and blood flow upon MFPF-PO2 measurements. The response time of the MFPF FOXY-AL300 probe was adequate for real-time sensing in the blood phase.

  13. On the Effects of Reactive Oxygen Species and Nitric Oxide on Red Blood Cell Deformability

    Directory of Open Access Journals (Sweden)

    Lukas Diederich

    2018-05-01

    Full Text Available The main function of red blood cells (RBCs is the transport of respiratory gases along the vascular tree. To fulfill their task, RBCs are able to elastically deform in response to mechanical forces and, pass through the narrow vessels of the microcirculation. Decreased RBC deformability was observed in pathological conditions linked to increased oxidative stress or decreased nitric oxide (NO bioavailability, like hypertension. Treatments with oxidants and with NO were shown to affect RBC deformability ex vivo, but the mechanisms underpinning these effects are unknown. In this study we investigate whether changes in intracellular redox status/oxidative stress or nitrosation reactions induced by reactive oxygen species (ROS or NO may affect RBC deformability. In a case-control study comparing RBCs from healthy and hypertensive participants, we found that RBC deformability was decreased, and levels of ROS were increased in RBCs from hypertensive patients as compared to RBCs from aged-matched healthy controls, while NO levels in RBCs were not significantly different. To study the effects of oxidants on RBC redox state and deformability, RBCs from healthy volunteers were treated with increasing concentrations of tert-butylhydroperoxide (t-BuOOH. We found that high concentrations of t-BuOOH (≥ 1 mM significantly decreased the GSH/GSSG ratio in RBCs, decreased RBC deformability and increased blood bulk viscosity. Moreover, RBCs from Nrf2 knockout (KO mice, a strain genetically deficient in a number of antioxidant/reducing enzymes, were more susceptible to t-BuOOH-induced impairment in RBC deformability as compared to wild type (WT mice. To study the role of NO in RBC deformability we treated RBC suspensions from human volunteers with NO donors and nitrosothiols and analyzed deformability of RBCs from mice lacking the endothelial NO synthase (eNOS. We found that NO donors induced S-nitrosation of the cytoskeletal protein spectrin, but did not affect

  14. Influence of skin blood flow and source-detector distance on near-infrared spectroscopy-determined cerebral oxygenation in humans

    DEFF Research Database (Denmark)

    Hirasawa, Ai; Yanagisawa, Shintaro; Tanaka, Naoki

    2015-01-01

    Most near-infrared spectroscopy (NIRS) apparatus fails to isolate cerebral oxygenation from an extracranial contribution although they use different source-detector distances. Nevertheless, the effect of different source-detector distances and change in extracranial blood flow on the NIRS signal...... in a semi-recumbent position, while extracranial blood flow was restricted by application of four different pressures (+20 to +80 mmHg) to the left temporal artery. The O2 Hb was measured at the forehead via a multidistance probe (source-detector distance; 15, 22·5 and 30 mm), and SkBF was determined...... by laser Doppler. Heart rate and blood pressure were unaffected by application of pressure to the temporal artery, while SkBF gradually decreased (Papplied pressure...

  15. Peripheral vascular effects on auscultatory blood pressure measurement.

    Science.gov (United States)

    Rabbany, S Y; Drzewiecki, G M; Noordergraaf, A

    1993-01-01

    Experiments were conducted to examine the accuracy of the conventional auscultatory method of blood pressure measurement. The influence of the physiologic state of the vascular system in the forearm distal to the site of Korotkoff sound recording and its impact on the precision of the measured blood pressure is discussed. The peripheral resistance in the arm distal to the cuff was changed noninvasively by heating and cooling effects and by induction of reactive hyperemia. All interventions were preceded by an investigation of their effect on central blood pressure to distinguish local effects from changes in central blood pressure. These interventions were sufficiently moderate to make their effect on central blood pressure, recorded in the other arm, statistically insignificant (i.e., changes in systolic [p cooling experiments was statistically significant (p < 0.001). Moreover, both measured systolic (p < 0.004) and diastolic (p < 0.001) pressure decreases during the reactive hyperemia experiments were statistically significant. The findings demonstrate that alteration in vascular state generates perplexing changes in blood pressure, hence confirming experimental observations by earlier investigators as well as predictions by our model studies.

  16. Critical Evaluation of Blood Volume Measurements during Hemodialysis

    NARCIS (Netherlands)

    Dasselaar, Judith J.; van der Sande, Frank M.; Franssen, Casper F. M.

    2012-01-01

    Devices that continuously measure relative blood volume (RBV) changes during hemodialysis (HD) are increasingly used for the prevention of dialysis hypotension and fine-tuning of dry weight. However, RBV measurements are subject to various limitations. First, RBV devices provide information on

  17. Noninvasive MRI measurement of the absolute cerebral blood volume-cerebral blood flow relationship during visual stimulation in healthy humans.

    Science.gov (United States)

    Ciris, Pelin Aksit; Qiu, Maolin; Constable, R Todd

    2014-09-01

    The relationship between cerebral blood volume (CBV) and cerebral blood flow (CBF) underlies blood oxygenation level-dependent functional MRI signal. This study investigates the potential for improved characterization of the CBV-CBF relationship in humans, and examines sex effects as well as spatial variations in the CBV-CBF relationship. Healthy subjects were imaged noninvasively at rest and during visual stimulation, constituting the first MRI measurement of the absolute CBV-CBF relationship in humans with complete coverage of the functional areas of interest. CBV and CBF estimates were consistent with the literature, and their relationship varied both spatially and with sex. In a region of interest with stimulus-induced activation in CBV and CBF at a significance level of the P < 0.05, a power function fit resulted in CBV = 2.1 CBF(0.32) across all subjects, CBV = 0.8 CBF(0.51) in females and CBV = 4.4 CBF(0.15) in males. Exponents decreased in both sexes as ROIs were expanded to include less significantly activated regions. Consideration for potential sex-related differences, as well as regional variations under a range of physiological states, may reconcile some of the variation across literature and advance our understanding of the underlying cerebrovascular physiology. Copyright © 2013 Wiley Periodicals, Inc.

  18. Cine-CT measurement of cortical renal blood flow

    International Nuclear Information System (INIS)

    Jaschke, W.R.; Gould, R.G.; Cogan, M.G.; Sievers, R.; Lipton, M.J.

    1987-01-01

    A modified indicator-dilution technique using radiographic contrast material and a cine-CT scanner was used to measure blood flow in the renal cortex of dogs. To validate this technique, CT measurements were correlated with simultaneous measurements of flow determined by radioactive microspheres. Measurements were taken during euvolemic conditions and after hemorrhage. Thirty-nine measurements were compared, covering a flow range from 1 to 7 ml min-1 g-1, and a good correlation was found between the cine-CT and microsphere results (r = 0.93; p less than 0.001). Additionally, cine-CT measurements were made of the mean transit time (MTT) of contrast material through the renal cortex, and the reciprocal of these MTT values was also well correlated to microsphere determined flow (r = 0.94; p less than 0.001). Thus, cine-CT appears to be a promising new technique for measuring renal blood flow

  19. The coupling of cerebral blood flow and oxygen metabolism with brain activation is similar for simple and complex stimuli in human primary visual cortex.

    Science.gov (United States)

    Griffeth, Valerie E M; Simon, Aaron B; Buxton, Richard B

    2015-01-01

    Quantitative functional MRI (fMRI) experiments to measure blood flow and oxygen metabolism coupling in the brain typically rely on simple repetitive stimuli. Here we compared such stimuli with a more naturalistic stimulus. Previous work on the primary visual cortex showed that direct attentional modulation evokes a blood flow (CBF) response with a relatively large oxygen metabolism (CMRO2) response in comparison to an unattended stimulus, which evokes a much smaller metabolic response relative to the flow response. We hypothesized that a similar effect would be associated with a more engaging stimulus, and tested this by measuring the primary human visual cortex response to two contrast levels of a radial flickering checkerboard in comparison to the response to free viewing of brief movie clips. We did not find a significant difference in the blood flow-metabolism coupling (n=%ΔCBF/%ΔCMRO2) between the movie stimulus and the flickering checkerboards employing two different analysis methods: a standard analysis using the Davis model and a new analysis using a heuristic model dependent only on measured quantities. This finding suggests that in the primary visual cortex a naturalistic stimulus (in comparison to a simple repetitive stimulus) is either not sufficient to provoke a change in flow-metabolism coupling by attentional modulation as hypothesized, that the experimental design disrupted the cognitive processes underlying the response to a more natural stimulus, or that the technique used is not sensitive enough to detect a small difference. Copyright © 2014 Elsevier Inc. All rights reserved.

  20. Multi-regional investigation of the relationship between functional MRI blood oxygenation level dependent (BOLD activation and GABA concentration.

    Directory of Open Access Journals (Sweden)

    Ashley D Harris

    Full Text Available Several recent studies have reported an inter-individual correlation between regional GABA concentration, as measured by MRS, and the amplitude of the functional blood oxygenation level dependent (BOLD response in the same region. In this study, we set out to investigate whether this coupling generalizes across cortex. In 18 healthy participants, we performed edited MRS measurements of GABA and BOLD-fMRI experiments using regionally related activation paradigms. Regions and tasks were the: occipital cortex with a visual grating stimulus; auditory cortex with a white noise stimulus; sensorimotor cortex with a finger-tapping task; frontal eye field with a saccade task; and dorsolateral prefrontal cortex with a working memory task. In contrast to the prior literature, no correlation between GABA concentration and BOLD activation was detected in any region. The origin of this discrepancy is not clear. Subtle differences in study design or insufficient power may cause differing results; these and other potential reasons for the discrepant results are discussed. This negative result, although it should be interpreted with caution, has a larger sample size than prior positive results, and suggests that the relationship between GABA and the BOLD response may be more complex than previously thought.

  1. Measurement of oxygen consumption rate of osteoblasts from ...

    African Journals Online (AJOL)

    The cells were evaluated through live/dead assay, hematoxylin-eosin (HE) and alkaline phosphatase (ALP) staining. Moreover, Von-Kossa staining and Alizarin Red S staining were carried out for mineralized nodule formation. Following this, the oxygen consumption rates of osteoblasts in the earlier mentioned different ...

  2. Absolute quantum yield measurements for the formation of oxygen ...

    Indian Academy of Sciences (India)

    Unknown

    Abstract. The dynamics of formation of oxygen atoms after UV photoexcitation of .... The SO2 pressure in the cell was typically 30–55 mTorr (monitored by an MKS .... With this value the quantum yield for O(3P) formation could be calculated to.

  3. Noninvasive measurement of cerebral venous oxygenation in neonates with a multi-wavelength, fiber-coupled laser diode optoacoustic system

    Science.gov (United States)

    Herrmann, Stephen; Petrov, Irene Y.; Petrov, Yuriy; Fonseca, Rafael A.; Richardson, C. Joan; Shanina, Ekaterina; Prough, Donald S.; Esenaliev, Rinat O.

    2018-03-01

    Noninvasive measurement of cerebral venous oxygenation in neonates could provide critical information for clinicians such as cerebral hypoxia without the risks involved with invasive catheterization. Evaluation of cerebral hypoxia is important in many clinical settings such as hypoxic-ischemic encephalopathy, perfusion monitoring in cardiovascular surgery or in traumatic brain injury. By probing the superior sagittal sinus (SSS), a large central cerebral vein, we can obtain stable signals with our recently developed multi-wavelength, fiber-coupled laser diode optoacoustic system for measurement of SSS blood oxygenation. The neonatal SSS oxygenation was measured in the reflection mode through open anterior and posterior fontanelles without obscuration by the overlying calvarium. In the transmission mode it was measured through the skull in the occipital area. Our device is lightweight, easily maneuverable, and user friendly for physicians. We monitored the SSS oxygenation in neonates admitted to the Neonatal Intensive Care Unit (NICU) of UTMB with varying gestation, birth weight and clinical histories to identify normal range and difference between neonates with and without risk factors for cerebral hypoxia.

  4. Muscle contraction duration and fibre recruitment influence blood flow and oxygen consumption independent of contractile work during steady-state exercise in humans.

    Science.gov (United States)

    Richards, Jennifer C; Crecelius, Anne R; Kirby, Brett S; Larson, Dennis G; Dinenno, Frank A

    2012-06-01

    We tested the hypothesis that, among conditions of matched contractile work, shorter contraction durations and greater muscle fibre recruitment result in augmented skeletal muscle blood flow and oxygen consumption ( ) during steady-state exercise in humans. To do so, we measured forearm blood flow (FBF; Doppler ultrasound) during 4 min of rhythmic hand-grip exercise in 24 healthy young adults and calculated forearm oxygen consumption ( ) via blood samples obtained from a catheter placed in retrograde fashion into a deep vein draining the forearm muscle. In protocol 1 (n = 11), subjects performed rhythmic isometric hand-grip exercise at mild and moderate intensities during conditions in which time-tension index (isometric analogue of work) was held constant but contraction duration was manipulated. In this protocol, shorter contraction durations led to greater FBF (184 ± 25 versus 164 ± 25 ml min(-1)) and (23 ± 3 versus 17 ± 2 ml min(-1); both P flow. Our collective data indicate that, among matched workloads, shorter contraction duration and greater muscle fibre recruitment augment FBF and during mild-intensity forearm exercise, and that muscle blood flow is more closely related to metabolic cost ( ) rather than contractile work per se during steady-state exercise in humans.

  5. Noninvasive blood pressure measurement scheme based on optical fiber sensor

    Science.gov (United States)

    Liu, Xianxuan; Yuan, Xueguang; Zhang, Yangan

    2016-10-01

    Optical fiber sensing has many advantages, such as volume small, light quality, low loss, strong in anti-jamming. Since the invention of the optical fiber sensing technology in 1977, optical fiber sensing technology has been applied in the military, national defense, aerospace, industrial, medical and other fields in recent years, and made a great contribution to parameter measurement in the environment under the limited condition .With the rapid development of computer, network system, the intelligent optical fiber sensing technology, the sensor technology, the combination of computer and communication technology , the detection, diagnosis and analysis can be automatically and efficiently completed. In this work, we proposed a noninvasive blood pressure detection and analysis scheme which uses optical fiber sensor. Optical fiber sensing system mainly includes the light source, optical fiber, optical detector, optical modulator, the signal processing module and so on. wavelength optical signals were led into the optical fiber sensor and the signals reflected by the human body surface were detected. By comparing actual testing data with the data got by traditional way to measure the blood pressure we can establish models for predicting the blood pressure and achieve noninvasive blood pressure measurement by using spectrum analysis technology. Blood pressure measurement method based on optical fiber sensing system is faster and more convenient than traditional way, and it can get accurate analysis results in a shorter period of time than before, so it can efficiently reduce the time cost and manpower cost.

  6. Laser Doppler flowmetry for measurement of laminar capillary blood flow in the horse

    Science.gov (United States)

    Adair, Henry S., III

    1998-07-01

    Current methods for in vivo evaluation of digital hemodynamics in the horse include angiography, scintigraphy, Doppler ultrasound, electromagnetic flow and isolated extracorporeal pump perfused digit preparations. These techniques are either non-quantifiable, do not allow for continuous measurement, require destruction of the horse orare invasive, inducing non- physiologic variables. In vitro techniques have also been reported for the evaluation of the effects of vasoactive agents on the digital vessels. The in vitro techniques are non-physiologic and have evaluated the vasculature proximal to the coronary band. Lastly, many of these techniques require general anesthesia or euthanasia of the animal. Laser Doppler flowmetry is a non-invasive, continuous measure of capillary blood flow. Laser Doppler flowmetry has been used to measure capillary blood flow in many tissues. The principle of this method is to measure the Doppler shift, that is, the frequency change that light undergoes when reflected by moving objects, such as red blood cells. Laser Doppler flowmetry records a continuous measurement of the red cell motion in the outer layer of the tissue under study, with little or no influence on physiologic blood flow. This output value constitutes the flux of red cells and is reported as capillary perfusion units. No direct information concerning oxygen, nutrient or waste metabolite exchange in the surrounding tissue is obtained. The relationship between the flowmeter output signal and the flux of red blood cells is linear. The principles of laser Doppler flowmetry will be discussed and the technique for laminar capillary blood flow measurements will be presented.

  7. Noninvasive measurement of blood flow and extraction fraction

    Energy Technology Data Exchange (ETDEWEB)

    Peters, A.M.; Gunasekera, R.D.; Henderson, B.L.; Brown, J.; Lavender, J.P.; De Souza, M.; Ash, J.M.; Gilday, D.L.

    1987-10-01

    We describe the theory of a technique for the noninvasive measurement of organ blood flow which is based on the principle of fractionation of cardiac output and is applicable with any recirculating gamma emitting tracer. The technique effectively determines the count rate that would be recorded over the organ if the tracer behaved like radiolabelled microspheres and was completely trapped in the organ's vascular bed on first pass. After correction for organ depth, the estimated first pass activity plateau, expressed as a fraction of the injected dose is equal to the organ's fraction of the cardiac output (CO). By extending the theory, organ extraction fraction of extractable tracers or mean transit time of nonextractable tracers can be measured. The technique was applied to the measurement of renal blood flow in the native and transplanted kidney, splenic blood flow, the extraction fraction of DTPA by the kidney and of sulphur colloid by the spleen.

  8. Noninvasive measurement of blood flow and extraction fraction

    International Nuclear Information System (INIS)

    Peters, A.M.; Gunasekera, R.D.; Henderson, B.L.; Brown, J.; Lavender, J.P.; De Souza, M.; Ash, J.M.; Gilday, D.L.

    1987-01-01

    We describe the theory of a technique for the noninvasive measurement of organ blood flow which is based on the principle of fractionation of cardiac output and is applicable with any recirculating gamma emitting tracer. The technique effectively determines the count rate that would be recorded over the organ if the tracer behaved like radiolabelled microspheres and was completely trapped in the organ's vascular bed on first pass. After correction for organ depth, the estimated first pass activity plateau, expressed as a fraction of the injected dose is equal to the organ's fraction of the cardiac output (CO). By extending the theory, organ extraction fraction of extractable tracers or mean transit time of nonextractable tracers can be measured. The technique was applied to the measurement of renal blood flow in the native and transplanted kidney, splenic blood flow, the extraction fraction of DTPA by the kidney and of sulphur colloid by the spleen. (author)

  9. Myocardial blood flow and its transit time, oxygen utilization, and efficiency of highly endurance-trained human heart.

    Science.gov (United States)

    Heinonen, Ilkka; Kudomi, Nobuyuki; Kemppainen, Jukka; Kiviniemi, Antti; Noponen, Tommi; Luotolahti, Matti; Luoto, Pauliina; Oikonen, Vesa; Sipilä, Hannu T; Kopra, Jaakko; Mononen, Ilkka; Duncker, Dirk J; Knuuti, Juhani; Kalliokoski, Kari K

    2014-07-01

    Highly endurance-trained athlete's heart represents the most extreme form of cardiac adaptation to physical stress, but its circulatory alterations remain obscure. In the present study, myocardial blood flow (MBF), blood mean transit time (MTT), oxygen extraction fraction (OEF) and consumption (MVO2), and efficiency of cardiac work were quantified in highly trained male endurance athletes and control subjects at rest and during supine cycling exercise using [(15)O]-labeled radiotracers and positron emission tomography. Heart rate and MBF were lower in athletes both at rest and during exercise. OEF increased in response to exercise in both groups, but was higher in athletes (70 ± 21 vs. 63 ± 11 % at rest and 86 ± 13 vs. 73 ± 10 % during exercise). MTT was longer and vascular resistance higher in athletes both at rest and during exercise, but arterial content of 2,3-diphosphoglycerate (oxygen affinity) was unchanged. MVO2 per gram of myocardium trended (p = 0.08) lower in athletes both at rest and during exercise, while myocardial efficiency of work and MVO2 per beat were not different between groups. Arterial levels of free fatty acids were ~twofold higher in athletes likely leading to higher myocardial fatty acid oxidation and hence oxygen cost, which may have blunted the bradycardia-induced decrease in MVO2. Finally, the observed group differences in MBF, OEF, MTT and vascular resistance remained significant also after they were controlled for differences in MVO2. In conclusion, in highly endurance-trained human heart, increased myocardial blood transition time enables higher oxygen extraction levels with a lower myocardial blood flow and higher vascular resistance. These physiological adaptations to exercise training occur independently of the level of oxygen consumption and together with training-induced bradycardia may serve as mechanisms to increase functional reserve of the human heart.

  10. A Simple Experiment To Measure the Content of Oxygen in the Air Using Heated Steel Wool

    Science.gov (United States)

    Vera, Francisco; Rivera, Rodrigo; Nunez, Cesar

    2011-01-01

    The typical experiment to measure the oxygen content in the atmosphere uses the rusting of steel wool inside a closed volume of air. Two key aspects of this experiment that make possible a successful measurement of the content of oxygen in the air are the use of a closed atmosphere and the use of a chemical reaction that involves the oxidation of…

  11. Preanalytical Biases in the Measurement of Human Blood Sphingolipids

    Directory of Open Access Journals (Sweden)

    Robert Brunkhorst

    2018-05-01

    Full Text Available Dysregulation of blood sphingolipids is an emerging topic in clinical science. The objective of this study was to determine preanalytical biases that typically occur in clinical and translational studies and that influence measured blood sphingolipid levels. Therefore, we collected blood samples from four healthy male volunteers to investigate the effect of storage conditions (time, temperature, long-term storage, freeze–thaw cycles, blood drawing (venous or arterial sampling, prolonged venous compression, and sample preparation (centrifugation, freezing on sphingolipid levels measured by LC-MS/MS. Our data show that sphingosine 1-phosphate (S1P and sphinganine 1-phosphate (SA1P were upregulated in whole blood samples in a time- and temperature-dependent manner. Increased centrifugation at higher speeds led to lower amounts of S1P and SA1P. All other preanalytical biases did not significantly alter the amounts of S1P and SA1P. Further, in almost all settings, we did not detect differences in (dihydroceramide levels. In summary, besides time-, temperature-, and centrifugation-dependent changes in S1P and SA1P levels, sphingolipids in blood remained stable under practically relevant preanalytical conditions.

  12. Radiolabeled microsphere measurements of alveolar bone blood flow in dogs

    International Nuclear Information System (INIS)

    Kaplan, M.L.; Jeffcoat, M.K.; Goldhaber, P.

    1978-01-01

    Radiolabeled microspheres were injected into the left cardiac ventricle in healthy adult dogs to quantify blood in maxillary and mandibular alveolar bone. Heart rate, arterial blood pressure and pulse contour were monitored throughout each experiment. Blood flow in maxillary alveolar bone was more than 30 % greater (p<.001) than in mandibular alveolar bone. Alveolar bone blood flow (mean +- S.D.) measured as ml/min per gram was 0.12 +- .02 in the maxilla compared to 0.09 +- .02 in the mandible. The cardiovascular parameters monitored were constant immediately prior to the injection of microspheres and remained unchanged during and following injection. It is possible that radiolabeled microspheres can be used to quantify the circulatory changes in alveolar bone during the development of destructive periodontal disease in dogs. (author)

  13. Should direct measurements of tumor oxygenation relate to the radiobiological hypoxic fraction of a tumor?

    International Nuclear Information System (INIS)

    Fenton, Bruce M.; Kiani, Mohammad F.; Siemann, Dietmar W.

    1995-01-01

    Purpose: Numerous previous studies have attempted to relate the radiobiological hypoxic fraction (HF) to direct measures of tumor oxygenation such as HbO 2 saturations, tumor pO 2 levels, or hypoxic cell labeling. Although correlations have been found within tumor lines, no overall relationships were seen across tumor lines. The current objective was to examine the effect on HF of changes in the fractions of the oxygenated and anoxic tumor cells that remain clonogenic. Methods and Materials: A mathematical model was developed that relates the HF to direct measures of tumor oxygenation. The primary assumptions were that: (a) the tumor is divided into distinct compartments of either fully oxygenated or fully anoxic cells, and (b) the survival of the oxygenated cells is negligible compared to that of the anoxic cells. Based on these assumptions, the HF is plotted as a function of the fractions of clonogenic or nonclonogenic, and oxygenated or anoxic cells. Results: If all cells are clonogenic, then the HF equals the fraction of anoxic cells. If a higher fraction of anoxic than oxygenated cells are nonclonogenic, then the HF will be overestimated by the fraction of the tumor measured to be anoxic using direct measuring techniques. If a higher fraction of the oxygenated than anoxic cells are nonclonogenic, the HF will be underestimated by the fraction of anoxic cells. Conclusion: Correlations between the HF and direct measures of tumor oxygenation have been described within tumor lines evaluated under different physiological condition. However, such relationships can be totally unpredictable between different tumors if the fraction of the anoxic cells that is clonogenic varies substantially. Clearly, if tumor anoxia cannot be detected using direct measures, this is an accurate indication that the tumor is well oxygenated. When tumor anoxia is present, however, the conclusions are ambiguous. Even when a small fraction of the tumor is measured as anoxic, direct measures

  14. Whole-brain blood flow and oxygen metabolism in the rat after halothane anesthesia

    Energy Technology Data Exchange (ETDEWEB)

    Gjedde, A; Hindfeldt, B [Cerebrovascular Research Center, Department of Neurology, The New York Hospital-Cornell Medical Center, New York, U.S.A.; Department of Neurology, University Hospital, Lund, Sweden)

    1975-01-01

    A recent modification of the Kety-Schmidt wash-out technique for /sup 133/xenon was used to measure whole-brain flow (CBF) and oxygen consumption (CMRsub(o2)) 1 to 4 hours after termination of halothane anesthesia in 15 Wistar rats. In this 3-hour experimental period, mean CBF and CMRsub(o2) were reduced to 29 and 43 percent of control values, respectively. CBF and CMRsub(o2) determined at the beginning and end of the experimental period were not significantly different from each other. Cerebral venous O/sub 2/ tension was significantly higher than in the control group, supporting recent suggestions of a primary, intrinsic effect of halothane on the homeostatic control of this variable. It is concluded that halothane is not useful for cerebral metabolic studies in the rat.

  15. Photoplethysmographic signals and blood oxygen saturation values during artificial hypothermia in healthy volunteers

    International Nuclear Information System (INIS)

    Shafique, M; Kyriacou, P A

    2012-01-01

    Pulse oximetry utilizes the technique of photoplethysmography to estimate arterial oxygen saturation (SpO 2 ) values. During hypothermia, the amplitude of the photoplethysmograph (PPG) is compromised which can lead to inaccurate estimation of SpO 2 . A new mutlimode PPG/pulse oximeter sensor was developed to investigate the behaviour of PPGs during conditions of induced hypothermia (hand immersed in an ice bath). PPG measurements from 20 volunteers were conducted and SpO 2 values were estimated at all stages of the experiment. Good quality PPG signals were observed from the majority of the volunteers at almost all hand temperatures. At low temperature ranges, from 13 to 21 °C, the failure rate to estimate SpO 2 values from the multimode transreflectance PPG sensor was 2.4% as compared to the commercial pulse oximeter with a failure rate of 70%. (paper)

  16. A novel approach to office blood pressure measurement: 30-minute office blood pressure vs daytime ambulatory blood pressure

    NARCIS (Netherlands)

    Wel, M.C. van der; Buunk, I.E.; Weel, C. van; Thien, Th.; Bakx, J.C.

    2011-01-01

    PURPOSE: Current office blood pressure measurement (OBPM) is often not executed according to guidelines and cannot prevent the white-coat effect. Serial, automated, oscillometric OBPM has the potential to overcome both these problems. We therefore developed a 30-minute OBPM method that we compared

  17. The measurement of limb blood flow using technetium-labelled red blood cells

    International Nuclear Information System (INIS)

    Parkin, A; Robinson, P.J.; Wiggins, P.A.; Leveson, S.H.; Salter, M.C.P.; Matthews, I.F.; Ware, F.M.

    1986-01-01

    A method for measuring blood flow below the knee during reactive hyperaemia induced by 3 min of arterial occlusion has been developed. Subjects are positioned with lower limbs within the field of view of a gamma camera and pneumatic cuffs are placed below the knees to isolate the blood and induce a hyperaemic response. The remaining blood pool is labelled with 99 Tcsup(m)-labelled red cells. Blood flows have been derived from the initial gradients of time-activity curves and from equilibrium blood sampling. The technique has been validated using a tissue-equivalent leg phantom and peristaltic pump. The method has been applied to a small group of patients with peripheral vascular disease and to normal controls. The mean value (+-SD) of limb perfusion for normal controls was found to be 16.4+-3.0 ml/100 ml/min and for patients with intermittent claudication was 5.1+-2.6 ml/100 ml/min. Flow measurements are found to correlate with clinical findings and with symptoms. Reproducibility (established by repeated measurements) is high. The method is well tolerated even by patients suffering from rest pain. (author)

  18. Measurement of limb blood flow using technetium-labelled red blood cells

    Energy Technology Data Exchange (ETDEWEB)

    Parkin, A; Robinson, P.J.; Wiggins, P.A.; Leveson, S.H.; Salter, M.C.P.; Matthews, I.F.; Ware, F.M.

    1986-05-01

    A method for measuring blood flow below the knee during reactive hyperaemia induced by 3 min of arterial occlusion has been developed. Subjects are positioned with lower limbs within the field of view of a gamma camera and pneumatic cuffs are placed below the knees to isolate the blood and induce a hyperaemic response. The remaining blood pool is labelled with /sup 99/Tcsup(m)-labelled red cells. Blood flows have been derived from the initial gradients of time-activity curves and from equilibrium blood sampling. The technique has been validated using a tissue-equivalent leg phantom and peristaltic pump. The method has been applied to a small group of patients with peripheral vascular disease and to normal controls. The mean value (+-SD) of limb perfusion for normal controls was found to be 16.4 +- 3.0 ml/100 ml/min and for patients with intermittent claudication was 5.1 +- 2.6 ml/100 ml/min. Flow measurements are found to correlate with clinical findings and with symptoms. Reproducibility (established by repeated measurements) is high. The method is well tolerated even by patients suffering from rest pain.

  19. Partial neuromuscular blockade in humans enhances muscle blood flow during exercise independently of muscle oxygen uptake and acetylcholine receptor blockade

    DEFF Research Database (Denmark)

    Hellsten, Ylva; Krustrup, Peter; Iaia, F Marcello

    2009-01-01

    This study examined the role of acetylcholine for skeletal muscle blood flow during exercise by use of the competitive neuromuscular blocking agent cisatracurium in combination with the acetylcholine receptor blocker glycopyrrone. Nine healthy male subjects performed a 10-min bout of one-legged k......This study examined the role of acetylcholine for skeletal muscle blood flow during exercise by use of the competitive neuromuscular blocking agent cisatracurium in combination with the acetylcholine receptor blocker glycopyrrone. Nine healthy male subjects performed a 10-min bout of one...... conductance during exercise, events that are not associated with either acetylcholine or an increased oxygen demand. The results do not support an essential role for acetylcholine, released form the neuromuscular junction, in exercise hyperaemia or for the enhanced blood flow during neuromuscular blockade....... The enhanced exercise hyperemia during partial neuromuscular blockade may be related to a greater recruitment of fast-twitch muscle fibres. Key words: blood flow, neuromuscular blockade, exercise, skeletal muscle....

  20. The relationship between the cerebral blood flow, oxygen consumption and glucose metabolism in primary degenerative dementia

    International Nuclear Information System (INIS)

    Kuwabara, Yasuo; Ichiya, Yuichi; Ichimiya, Atsushi; Sasaki, Masayuki; Akashi, Yuko; Yoshida, Tsuyoshi; Fukumura, Toshimitsu; Masada, Kouji

    1995-01-01

    The CBF, CMRO 2 and CMRGlu were measured in patients with primary degenerative dementia including 5 patients with dementia of Alzheimer's type and 4 patients with Pick's disease, and then the correlation between the cerebral blood flow and energy metabolism was evaluated. The control subjects consisted of 5 age-matched normal volunteers. The CBF, CMRO 2 and CMRGlu decreased in the bilateral frontal, temporal and parietal regions in the patients with Alzheimer's dementia, while they decreased in the bilateral frontal and temporal regions in the patients with Pick's disease. Both the CBF and CMRO 2 were closely correlated with each other. However, the CMRGlu was more severely impaired than the CBF or CMRO 2 in both pathological conditions. These results suggested that CMRGlu began to decrease before the reduction of the aerobic metabolism and thus measuring the CMRGlu is considered to be the most sensitive method for detecting abnormal regions in primary degenerative dementia. (author)

  1. CLA supplementation and aerobic exercise lower blood triacylglycerol, but have no effect on peak oxygen uptake or cardiorespiratory fatigue thresholds.

    Science.gov (United States)

    Jenkins, Nathaniel D M; Buckner, Samuel L; Cochrane, Kristen C; Bergstrom, Haley C; Goldsmith, Jacob A; Weir, Joseph P; Housh, Terry J; Cramer, Joel T

    2014-09-01

    This study examined the effects of 6 weeks of conjugated linoleic acid (CLA) supplementation and moderate aerobic exercise on peak oxygen uptake (VO2 peak), the gas exchange threshold (GET), the respiratory compensation point (RCP), and serum concentrations of cholesterol, triacylglycerol, and glucose in humans. Thirty-four untrained to moderately trained men (mean ± SD; age = 21.5 ± 2.8 years; mass = 77.2 ± 9.5 kg) completed this double-blind, placebo controlled study and were randomly assigned to either a CLA (Clarinol A-80; n = 18) or placebo (PLA; sunflower oil; n = 16) group. Prior to and following 6 weeks of aerobic training (50% VO2 peak for 30 min, twice per week) and supplementation (5.63 g of total CLA isomers [of which 2.67 g was c9, t11 and 2.67 g was t10, c12] or 7.35 g high oleic sunflower oil per day), each participant completed an incremental cycle ergometer test to exhaustion to determine their [Formula: see text] peak, GET, and RCP and fasted blood draws were performed to measure serum concentrations of cholesterol, triacylglycerol, and glucose. Serum triacylglycerol concentrations were lower (p interactions (p 0.05) between the CLA and PLA groups. GET and RCP increased (p < 0.05) from pre- to post-training for both the CLA and PLA groups. Overall, these data suggested that CLA and aerobic exercise may have synergistic, blood triacylglycerol lowering effects, although CLA may be ineffective for enhancing aerobic exercise performance in conjunction with a 6-week aerobic exercise training program in college-age men.

  2. Functional neuroanatomy in depressed patients with sexual dysfunction: blood oxygenation level dependent functional MR imaging

    International Nuclear Information System (INIS)

    Yang, Jong Chul

    2004-01-01

    To demonstrate the functional neuroanatomy associated with sexual arousal visually evoked in depressed males who have underlying sexual dysfunction using Blood Oxygenation Level Dependent-based fMRI. Ten healthy volunteers (age range 21-55: mean 32.5 years), and 10 depressed subjects (age range 23-51: mean 34.4 years, mean Beck Depression Inventory score of 39.6 ± 5.9, mean Hamilton Rating Scale Depression (HAMD)-17 score of 33.5 ± 6.0) with sexual arousal dysfunction viewed erotic and neutral video films during functional magnetic resonance imaging (fMRI) with 1.5 T MR scanner (GE Signa Horizon). The fMRI data were obtained from 7 oblique planes using gradient-echo EPI (flip angle/TR/TE=90 .deg. /6000 ms/50 ms). The visual stimulation paradigm began with 60 sec of black screen, 150 sec of neutral stimulation with a documentary video film, 30 sec of black screen, 150 sec of sexual stimulation with an erotic video film followed by 30 sec of black screen. The brain activation maps and their quantification were analyzed by SPM99 program. There was a significant difference of brain activation between two groups during visual sexual stimulation. In depressed subjects, the level of activation during the visually evoked sexual arousal was significantly less than that of healthy volunteers, especially in the cerebrocortical areas of the hypothalamus, thalamus, caudate nucleus, and inferior and superior temporal gyri. On the other hand, the cerebral activation patterns during the neutral condition in both groups showed no significant differences (ρ < 0.01). This study is the first demonstration of the functional neuroanatomy of the brain associated with sexual dysfunction in depressed patients using fMRI. In order to validate our physiological neuroscience results, further studies that would include patients with other disorders and sexual dysfunction, and depressed patients without sexual dysfunction and their treatment response are needed

  3. Functional neuroanatomy in depressed patients with sexual dysfunction: blood oxygenation level dependent functional MR imaging

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Jong Chul [Chonnam National Univ. Hospital, Kwangju (Korea, Republic of)

    2004-06-15

    To demonstrate the functional neuroanatomy associated with sexual arousal visually evoked in depressed males who have underlying sexual dysfunction using Blood Oxygenation Level Dependent-based fMRI. Ten healthy volunteers (age range 21-55: mean 32.5 years), and 10 depressed subjects (age range 23-51: mean 34.4 years, mean Beck Depression Inventory score of 39.6 {+-} 5.9, mean Hamilton Rating Scale Depression (HAMD)-17 score of 33.5 {+-} 6.0) with sexual arousal dysfunction viewed erotic and neutral video films during functional magnetic resonance imaging (fMRI) with 1.5 T MR scanner (GE Signa Horizon). The fMRI data were obtained from 7 oblique planes using gradient-echo EPI (flip angle/TR/TE=90 .deg. /6000 ms/50 ms). The visual stimulation paradigm began with 60 sec of black screen, 150 sec of neutral stimulation with a documentary video film, 30 sec of black screen, 150 sec of sexual stimulation with an erotic video film followed by 30 sec of black screen. The brain activation maps and their quantification were analyzed by SPM99 program. There was a significant difference of brain activation between two groups during visual sexual stimulation. In depressed subjects, the level of activation during the visually evoked sexual arousal was significantly less than that of healthy volunteers, especially in the cerebrocortical areas of the hypothalamus, thalamus, caudate nucleus, and inferior and superior temporal gyri. On the other hand, the cerebral activation patterns during the neutral condition in both groups showed no significant differences ({rho} < 0.01). This study is the first demonstration of the functional neuroanatomy of the brain associated with sexual dysfunction in depressed patients using fMRI. In order to validate our physiological neuroscience results, further studies that would include patients with other disorders and sexual dysfunction, and depressed patients without sexual dysfunction and their treatment response are needed.

  4. Oxygen therapy - infants

    Science.gov (United States)

    ... breathe increased amounts of oxygen to get normal levels of oxygen in their blood. Oxygen therapy provides babies with the extra oxygen. Information Oxygen is a gas that the cells in your body need to work properly. The ...

  5. 21 CFR 864.5950 - Blood volume measuring device.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Blood volume measuring device. 864.5950 Section 864.5950 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Automated and Semi-Automated Hematology Devices...

  6. Simultaneous compared with sequential blood pressure measurement results in smaller inter-arm blood pressure differences

    NARCIS (Netherlands)

    van der Hoeven, Niels V.; Lodestijn, Sophie; Nanninga, Stephanie; van Montfrans, Gert A.; van den Born, Bert-Jan H.

    2013-01-01

    There are currently few recommendations on how to assess inter-arm blood pressure (BP) differences. The authors compared simultaneous with sequential measurement on mean BP, inter-arm BP differences, and within-visit reproducibility in 240 patients stratified according to age ( <50 or ≥60 years) and

  7. Oxygen Pickup Ions Measured by MAVEN Outside the Martian Bow Shock

    Science.gov (United States)

    Rahmati, A.; Cravens, T.; Larson, D. E.; Lillis, R. J.; Dunn, P.; Halekas, J. S.; Connerney, J. E. P.; Eparvier, F. G.; Thiemann, E.; Mitchell, D. L.; Jakosky, B. M.

    2015-12-01

    The MAVEN (Mars Atmosphere and Volatile EvolutioN) spacecraft entered orbit around Mars on September 21, 2014 and has since been detecting energetic oxygen pickup ions by its SEP (Solar Energetic Particles) and SWIA (Solar Wind Ion Analyzer) instruments. The oxygen pickup ions detected outside the Martian bowshock and in the upstream solar wind are associated with the extended hot oxygen exosphere of Mars, which is created mainly by the dissociative recombination of molecular oxygen ions with electrons in the ionosphere. We use analytic solutions to the equations of motion of pickup ions moving in the undisturbed upstream solar wind magnetic and motional electric fields and calculate the flux of oxygen pickup ions at the location of MAVEN. Our model calculates the ionization rate of oxygen atoms in the exosphere based on the hot oxygen densities predicted by Rahmati et al. (2014), and the sources of ionization include photo-ionization, charge exchange, and electron impact ionization. The photo-ionization frequency is calculated using the FISM (Flare Irradiance Spectral Model) solar flux model, based on MAVEN EUVM (Extreme Ultra-Violet Monitor) measurements. The frequency of charge exchange between a solar wind proton and an oxygen atom is calculated using MAVEN SWIA solar wind proton flux measurements, and the electron impact ionization frequency is calculated based on MAVEN SWEA (Solar Wind Electron Analyzer) solar wind electron flux measurements. The solar wind magnetic field used in the model is from the measurements taken by MAVEN MAG (magnetometer) in the upstream solar wind. The good agreement between our predicted pickup oxygen fluxes and the MAVEN SEP and SWIA measured ones confirms detection of oxygen pickup ions and these model-data comparisons can be used to constrain models of hot oxygen densities and photochemical escape flux.

  8. Mapping of cerebral metabolic rate of oxygen using dynamic susceptibility contrast and blood oxygen level dependent MR imaging in acute ischemic stroke

    Energy Technology Data Exchange (ETDEWEB)

    Gersing, Alexandra S.; Schwaiger, Benedikt J. [Technical University Munich, Klinikum rechts der Isar, Department of Neuroradiology, Munich (Germany); University of California, Department of Radiology and Biomedical Imaging, San Francisco, CA (United States); Ankenbrank, Monika; Toth, Vivien; Bauer, Jan S.; Zimmer, Claus [Technical University Munich, Klinikum rechts der Isar, Department of Neuroradiology, Munich (Germany); Janssen, Insa [Technical University Munich, Department of Neurosurgery, Munich (Germany); Kooijman, Hendrik [Philips Healthcare, Hamburg (Germany); Wunderlich, Silke [Technical University Munich, Department of Neurology, Munich (Germany); Preibisch, Christine [Technical University Munich, Klinikum rechts der Isar, Department of Neuroradiology, Munich (Germany); Technical University Munich, Department of Neurology, Munich (Germany)

    2015-12-15

    MR-derived cerebral metabolic rate of oxygen utilization (CMRO{sub 2}) has been suggested to be analogous to PET-derived CMRO{sub 2} and therefore may be used for detection of viable tissue at risk for infarction. The purpose of this study was to evaluate MR-derived CMRO{sub 2} mapping in acute ischemic stroke in relation to established diffusion- and perfusion-weighted imaging. In 23 patients (mean age 63 ± 18.7 years, 11 women) with imaging findings for acute ischemic stroke, relative oxygen extraction fraction was calculated from quantitative transverse relaxation times (T2, T2*) and relative cerebral blood volume using a quantitative blood oxygenation level dependent (BOLD) approach in order to detect a local increase of deoxyhemoglobin. Relative CMRO{sub 2} (rCMRO{sub 2}) maps were calculated by multiplying relative oxygen extraction fraction (rOEF) by cerebral blood flow, derived from PWI. After co-registration, rCMRO{sub 2} maps were evaluated in comparison with apparent diffusion coefficient (ADC) and time-to-peak (TTP) maps. Mean rCMRO{sub 2} values in areas with diffusion-restriction or TTP/ADC mismatch were compared with rCMRO{sub 2} values in the contralateral tissue. In tissue with diffusion restriction, mean rCMRO{sub 2} values were significantly decreased compared to perfusion-impaired (17.9 [95 % confidence interval 10.3, 25.0] vs. 58.1 [95 % confidence interval 50.1, 70.3]; P < 0.001) and tissue in the contralateral hemisphere (68.2 [95 % confidence interval 61.4, 75.0]; P < 0.001). rCMRO{sub 2} in perfusion-impaired tissue showed no significant change compared to tissue in the contralateral hemisphere (58.1 [95 % confidence interval 50.1, 70.3] vs. 66.7 [95 % confidence interval 53.4, 73.4]; P = 0.34). MR-derived CMRO{sub 2} was decreased within diffusion-restricted tissue and stable within perfusion-impaired tissue, suggesting that this technique may be adequate to reveal different pathophysiological stages in acute stroke. (orig.)

  9. Direct measurement of oxygen in brown coals and carbochemical products by means of fast neutron analysis

    International Nuclear Information System (INIS)

    Raeppel, P.; Foerster, H.

    1990-01-01

    Analyses of elemental oxygen by means of fast neutron activation permit high-accuracy measurements of oxygen concentrations in East German brown coal; this applies to run-of-mine brown coal as well as to demineralized brown coal. The relative error was 4% in the first case and 2% in the latter case. Pre-washing with 1n ammonium acetate solution permits direct analyses of the oxygen bonded to the coal minerals. The method is applicable to other carbonaceous materials, e.g. coal ashes, solid hydrogenation residues, cokes, coal extracts, asphaltenes, oils, etc., at oxygen concentrations of 1-50%. (orig.) [de

  10. Expression of T helper cell-associated inflammatory mediator mRNAs in cells of bronchoalveolar lavage fluid samples and oxygen concentration in arterial blood samples from healthy horses exposed to hyperbaric oxygen.

    Science.gov (United States)

    Looijen, Maty G P; New, Dallas J; Fischer, Carrie D; Dardari, Rkia; Irwin, Karyn M; Berezowski, Christopher J; Bond, Stephanie L; Léguillette, Renaud

    2016-10-01

    OBJECTIVE To evaluate the mRNA expression of T helper (Th)1, Th2, and Th17 cell-associated inflammatory mediators in cells of bronchoalveolar lavage fluid samples collected from healthy horses exposed to hyperbaric oxygen (HBO) and to monitor blood oxygen concentration during and following HBO therapy. ANIMALS 8 healthy horses. PROCEDURES In a randomized controlled crossover design study, each horse was exposed (beginning day 1) to 100% oxygen at a maximum of 3 atmospheres absolute (304 kPa) daily for 10 days or ambient air at atmospheric pressure in the HBO chamber for an equivalent amount of time (control). Bronchoalveolar lavage fluid samples were collected on days 0 and 10. After validation of candidate reference genes, relative mRNA expressions of various innate inflammatory, Th1 cell-derived, Th2 cell-derived (including eotaxin-2), Th17 cell-derived, and regulatory cytokines were measured by quantitative PCR assays. For 3 horses, arterial blood samples were collected for blood gas analysis during a separate HBO session. RESULTS The optimal combination of reference genes was glyceraldehyde-3-phosphate dehydrogenase, hypoxanthine ribosyltransferase, and ribosomal protein L32. Compared with day 0 findings, expression of eotaxin-2 mRNA was significantly lower (0.12-fold reduction) and the percentage of neutrophils in bronchoalveolar lavage fluid samples was significantly lower on day 10 when horses received HBO therapy. Values of Pao2 rapidly increased (> 800 mm Hg) but immediately decreased to pretreatment values when HBO sessions ended. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that HBO therapy does not increase mRNA expression of inflammatory cytokines, but reduces eotaxin-2 mRNA transcription. The Pao2 increase was transient with no cumulative effects of HBO.

  11. In vivo mitochondrial oxygen tension measured by a delayed fluorescence lifetime technique

    NARCIS (Netherlands)

    Mik, Egbert G.; Johannes, Tanja; Zuurbier, Coert J.; Heinen, Andre; Houben-Weerts, Judith H. P. M.; Balestra, Gianmarco M.; Stap, Jan; Beek, Johan F.; Ince, Can

    2008-01-01

    Mitochondrial oxygen tension (mitoPO(2)) is a key parameter for cellular function, which is considered to be affected under various pathophysiological circumstances. Although many techniques for assessing in vivo oxygenation are available, no technique for measuring mitoPO(2) in vivo exists. Here we

  12. About Error in Measuring Oxygen Concentration by Solid-Electrolyte Sensors

    Directory of Open Access Journals (Sweden)

    V. I. Nazarov

    2008-01-01

    Full Text Available The paper evaluates additional errors while measuring oxygen concentration in a gas mixture by a solid-electrolyte cell. Experimental dependences of additional errors caused by changes in temperature in a sensor zone, discharge of gas mixture supplied to a sensor zone, partial pressure in the gas mixture and fluctuations in oxygen concentrations in the air.

  13. Simple technique for measuring relative renal blood flow

    International Nuclear Information System (INIS)

    Shames, D.M.; Korobkin, M.

    1976-01-01

    To determine whether externally monitored early renal uptake of 131 I-hippurate is proportional to renal blood flow, the renal uptake of 131 -hippurate at 1 to 2 min after injection was compared with the renal accumulation of radioactive carbonized microspheres in dogs. A renal artery catheter equipped with a balloon was used to decrease renal blood flow unilaterally. One minute after the intravenous injection of 100 μCi of 131 I-hippurate, about 1 μCi of either 85 Sr- or 95 Nb-labeled carbon microspheres was injected into the left ventricle. Radioactivity was measured over both kidneys. The total radioactivity within each kidney region of interest was corrected for background and integrated over the 1 to 2 min interval after injection. Thirteen measurements of relative renal blood flow were made for seven dogs. The dogs were then killed and both kidneys were excised and counted for the radioactivity of the microspheres. The 1 to 2-min relative renal uptake of 131 I-hippurate correlated well with relative microsphere uptake, suggesting that relative renal blood flow can be simply determined from the external measurements of renal uptake of 131 I-hippurate

  14. Average blood flow and oxygen uptake in the human brain during resting wakefulness

    DEFF Research Database (Denmark)

    Madsen, P L; Holm, S; Herning, M

    1993-01-01

    tracer between the brain and its venous blood is not reached. As a consequence, normal values for CBF and CMRO2 of 54 ml 100 g-1 min-1 and 3.5 ml 100 g-1 min-1 obtained with the Kety-Schmidt technique are an overestimation of the true values. Using the Kety-Schmidt technique we have performed 57...... the measured data, we find that the true average values for CBF and CMRO2 in the healthy young adult are approximately 46 ml 100 g-1 min-1 and approximately 3.0 ml 100 g-1 min-1. Previous studies have suggested that some of the variation in CMRO2 values could be ascribed to differences in cerebral venous...

  15. Nephron blood flow dynamics measured by laser speckle contrast imaging

    DEFF Research Database (Denmark)

    von Holstein-Rathlou, Niels-Henrik; Sosnovtseva, Olga V; Pavlov, Alexey N

    2011-01-01

    Tubuloglomerular feedback (TGF) has an important role in autoregulation of renal blood flow and glomerular filtration rate (GFR). Because of the characteristics of signal transmission in the feedback loop, the TGF undergoes self-sustained oscillations in single-nephron blood flow, GFR, and tubular...... simultaneously. The interacting nephron fields are likely to be more extensive. We have turned to laser speckle contrast imaging to measure the blood flow dynamics of 50-100 nephrons simultaneously on the renal surface of anesthetized rats. We report the application of this method and describe analytic...... pressure and flow. Nephrons interact by exchanging electrical signals conducted electrotonically through cells of the vascular wall, leading to synchronization of the TGF-mediated oscillations. Experimental studies of these interactions have been limited to observations on two or at most three nephrons...

  16. Regional cerebral blood flow measurement in brain tumors

    International Nuclear Information System (INIS)

    Izunaga, Hiroshi; Hirota, Yoshihisa; Takahashi, Mutsumasa; Fuwa, Isao; Kodama, Takafumi; Matsukado, Yasuhiko

    1986-01-01

    The regional cerebral blood flow (CBF) was determined on seventeen patients with brain tumors. Ring type single photon emission CT (SPECT) was used following intravenous injection of 133 Xe. Case materials included eleven meningiomas and six malignant gliomas. Evaluation was performed with emphasis on the following points; 1. Correlation of the flow data within tumors to the angiographic tumor stains, 2. Influence of tumors on the cerebral blood flow of the normal brain tissue, 3. Correlation between degree of peripheral edema and the flow data of the affected hemispheres. There was significant correlation between flow data within tumors and angiographic tumor stains in meningiomas. Influence of tumors on cerebral blood flow of the normal tissue was greater in meningiomas than in gliomas. There was negative correlation between the degree of peripheral edema and the flow data of the affected hemisphere. It has been concluded that the measurement of CBF in brain tumors is a valuable method in evaluation of brain tumors. (author)

  17. Regional cerebral blood flow measurement in brain tumors

    Energy Technology Data Exchange (ETDEWEB)

    Izunaga, Hiroshi; Hirota, Yoshihisa; Takahashi, Mutsumasa; Fuwa, Isao; Kodama, Takafumi; Matsukado, Yasuhiko

    1986-10-01

    The regional cerebral blood flow (CBF) was determined on seventeen patients with brain tumors. Ring type single photon emission CT (SPECT) was used following intravenous injection of /sup 133/Xe. Case materials included eleven meningiomas and six malignant gliomas. Evaluation was performed with emphasis on the following points; 1. Correlation of the flow data within tumors to the angiographic tumor stains, 2. Influence of tumors on the cerebral blood flow of the normal brain tissue, 3. Correlation between degree of peripheral edema and the flow data of the affected hemispheres. There was significant correlation between flow data within tumors and angiographic tumor stains in meningiomas. Influence of tumors on cerebral blood flow of the normal tissue was greater in meningiomas than in gliomas. There was negative correlation between the degree of peripheral edema and the flow data of the affected hemisphere. It has been concluded that the measurement of CBF in brain tumors is a valuable method in evaluation of brain tumors.

  18. Blood pressure measurement in obese patients: comparison between upper arm and forearm measurements.

    Science.gov (United States)

    Pierin, Angela M G; Alavarce, Débora C; Gusmão, Josiane L; Halpern, Alfredo; Mion, Décio

    2004-06-01

    It is well known that blood pressure measurement with a standard 12-13 cm wide cuff is erroneous for large arms. To compare arm blood pressure measurements with an appropriate cuff and forearm blood pressure measurements (BPM) with a standard cuff, and both measurements by the Photopletismography (Finapres) method. One hundred and twenty-nine obese patients were studied (body mass index=40+/-7 kg/m2). The patients had three arm BPM taken by an automatic oscillometric device using an appropriate cuff and three forearm BPM with a standard cuff in the sitting position after a five-minute rest. Data were analysed by the analysis of variance. The correction values were obtained by the linear regression test. Systolic and diastolic arm BPM with an appropriate cuff were significantly lower (pforearm BPM with a standard cuff. The measurements obtained by Finapres were significantly lower (pforearm systolic and diastolic blood pressures and upper arm diastolic blood pressure. The equation to correct BPM in forearm in obese patients with arm circumference between 32-44 cm was: systolic BPM=33.2+/-0.68 x systolic forearm BPM, and diastolic BPM=25.2+0.59 x forearm diastolic BPM. This study showed that forearm blood pressure measurement overestimates the values of arm blood pressure measurement. In addition, it is possible to correct forearm BPM with an equation.

  19. Pulmonary blood flow distribution measured by radionuclide computed tomography

    International Nuclear Information System (INIS)

    Maeda, H.; Itoh, H.; Ishii, Y.

    1982-01-01

    Distributions of pulmonary blood flow per unit lung volume were measured in sitting patients with a radionuclide computed tomography (RCT) by intravenously administered Tc-99m macroaggregates of human serum albumin (MAA). Four different types of distribution were distinguished, among which a group referred as type 2 had a three zonal blood flow distribution as previously reported (West and co-workers, 1964). The pulmonary arterial pressure (Pa) and the venous pressure (Pv) were determined in this group of distribution. These values showed satifactory agreements with the pulmonary artery pressure (Par) and the capillary wedged pressure (Pcw) measured by Swan-Ganz catheter in eighteen supine patients. Those good correlations enable to establish a noninvasive methodology for measurement of pulmonary vascular pressures

  20. Measurement of oxygen extraction fraction (OEF): An optimized BOLD signal model for use with hypercapnic and hyperoxic calibration.

    Science.gov (United States)

    Merola, Alberto; Murphy, Kevin; Stone, Alan J; Germuska, Michael A; Griffeth, Valerie E M; Blockley, Nicholas P; Buxton, Richard B; Wise, Richard G

    2016-04-01

    Several techniques have been proposed to estimate relative changes in cerebral metabolic rate of oxygen consumption (CMRO2) by exploiting combined BOLD fMRI and cerebral blood flow data in conjunction with hypercapnic or hyperoxic respiratory challenges. More recently, methods based on respiratory challenges that include both hypercapnia and hyperoxia have been developed to assess absolute CMRO2, an important parameter for understanding brain energetics. In this paper, we empirically optimize a previously presented "original calibration model" relating BOLD and blood flow signals specifically for the estimation of oxygen extraction fraction (OEF) and absolute CMRO2. To do so, we have created a set of synthetic BOLD signals using a detailed BOLD signal model to reproduce experiments incorporating hypercapnic and hyperoxic respiratory challenges at 3T. A wide range of physiological conditions was simulated by varying input parameter values (baseline cerebral blood volume (CBV0), baseline cerebral blood flow (CBF0), baseline oxygen extraction fraction (OEF0) and hematocrit (Hct)). From the optimization of the calibration model for estimation of OEF and practical considerations of hypercapnic and hyperoxic respiratory challenges, a new "simplified calibration model" is established which reduces the complexity of the original calibration model by substituting the standard parameters α and β with a single parameter θ. The optimal value of θ is determined (θ=0.06) across a range of experimental respiratory challenges. The simplified calibration model gives estimates of OEF0 and absolute CMRO2 closer to the true values used to simulate the experimental data compared to those estimated using the original model incorporating literature values of α and β. Finally, an error propagation analysis demonstrates the susceptibility of the original and simplified calibration models to measurement errors and potential violations in the underlying assumptions of isometabolism

  1. Application of language blood oxygenation level dependent functional MRI in the navigating operation of neurosurgery

    International Nuclear Information System (INIS)

    Liu Shuyong; Li Min; Yao Chengjun; Geng Daoying

    2011-01-01

    Objective: To verify the accuracy of blood oxygenation level dependent (BOLD)-based activation using electrocortical stimulation mapping (ESM) and explore the value of language fMRI in the navigating operation of neurosurgery. Methods: In 8 cases with brain tumors, BOLD-fMRI examinations were done before the operations. Under the state of awake anesthesia,the patients were aroused and ESM was conducted. Point-to-point comparison between the BOLD signal activations and the ESM was carried out under the surveillance of the neuro-navigation technology. In order to observe the sensibility and specificity of BOLD activations, the location of BOLD activations and the point of ESM was compared to calculate the stimulating positive points inside the regions of BOLD signals (real positive), outside BOLD regions (pseudo- negative), the stimulating negative points inside the regions of BOLD signals (pseudo-positive), and outside BOLD region (real negative). Two kinds of criteria for assessment were used. One was that the positive stimulating points were located in BOLD regions, and the other was that the positive stimulating points were located within 1 cm around the range of BOLD regions. Removal of the lesions were conducted with the tissue 1 cm around the language region preserved, and the cortex inside 0.5-1.0 cm distance from the positive points were retained. Results: Of the 8 cases, only 6 finished the tasks. Among them, 3 cases were with astrocytoma of grade 2, 2 were with astrocytoma of grade 3, and one with glioblastoma. The total number of stimulating points was 48, among which the positive points were 11. When the first criteria was applied, the sensitivity was 72.7% (8/11), and the specificity was 81.8% (30/37). When the second criteria was applied, the sensitivity was 82.0% (9/11), and the specificity was 75.6% (28/37). Follow-up after operation showed no aphasia occurred. Conclusions: BOLD-fMRI had a high sensitivity and specificity in displaying the language

  2. Measurement of regional hepatic blood flow by scintiphotosplenoportography

    Energy Technology Data Exchange (ETDEWEB)

    Kashiwagi, T; Kimura, K; Kamada, T; Abe, H [Osaka Univ. (Japan). Dept. of Radiology and Nuclear Medicine

    1978-08-01

    A new technique for estimating regional hepatic blood flow using the inert gas washout technique and scintillation camera following injection of /sup 133/Xe into the spleen is presented. This technique is easily, rapidly and repeatedly performed and permits the measurement of nutrient hepatic tissue blood flow. Measurement of regional hepatic blood flow in right and/or left lobes was performed in 28 patients. In all but one patient the right lobar flow value was equal to or greater than the left one. The right lobar flow was 86.20 +- 12.83 ml/100 gm/min in 3 patients without liver disease, 75.12 +- 14.54 ml/100 gm/min in 12 with chronic hepatitis and 51.24 +- 17.13 ml/100 gm/min in 11 with liver cirrhosis. This result suggests that hepatic tissue blood flow is significantly decreased in patients with liver cirrhosis. Scintillation camera images of initial xenon distribution in combination with monitor of washout curves over the liver also provide more information on the presence of extra- and intrahepatic shunts. Therefore, this technique appears to be clinically useful in evaluation of hemodynamic phenomena associated with liver diseases.

  3. Optically measured microvascular blood flow contrast of malignant breast tumors.

    Directory of Open Access Journals (Sweden)

    Regine Choe

    Full Text Available Microvascular blood flow contrast is an important hemodynamic and metabolic parameter with potential to enhance in vivo breast cancer detection and therapy monitoring. Here we report on non-invasive line-scan measurements of malignant breast tumors with a hand-held optical probe in the remission geometry. The probe employs diffuse correlation spectroscopy (DCS, a near-infrared optical method that quantifies deep tissue microvascular blood flow. Tumor-to-normal perfusion ratios are derived from thirty-two human subjects. Mean (95% confidence interval tumor-to-normal ratio using surrounding normal tissue was 2.25 (1.92-2.63; tumor-to-normal ratio using normal tissues at the corresponding tumor location in the contralateral breast was 2.27 (1.94-2.66, and using normal tissue in the contralateral breast was 2.27 (1.90-2.70. Thus, the mean tumor-to-normal ratios were significantly different from unity irrespective of the normal tissue chosen, implying that tumors have significantly higher blood flow than normal tissues. Therefore, the study demonstrates existence of breast cancer contrast in blood flow measured by DCS. The new, optically accessible cancer contrast holds potential for cancer detection and therapy monitoring applications, and it is likely to be especially useful when combined with diffuse optical spectroscopy/tomography.

  4. Measurement and interpretation of low levels of dissolved oxygen in ground water

    Science.gov (United States)

    White, A.F.; Peterson, M.L.; Solbau, R.D.

    1990-01-01

    A Rhodazine-D colorimetric technique was adapted to measure low-level dissolved oxygen concentrations in ground water. Prepared samples containing between 0 and 8.0 ??moles L-1 dissolved oxygen in equilibrium with known gas mixtures produced linear spectrophotometric absorbance with a lower detection limit of 0.2 ??moles L-1. Excellent reproducibility was found for solutions ranging in composition from deionized water to sea water with chemical interferences detected only for easily reduced metal species such as ferric ion, cupric ion, and hexavalent chromium. Such effects were correctable based on parallel reaction stoichiometries relative to oxygen. The technique, coupled with a downhole wire line tool, permitted low-level monitoring of dissolved oxygen in wells at the selenium-contaminated Kesterson Reservoir in California. Results indicated a close association between low but measurable dissolved oxygen concentrations and mobility of oxidized forms of selenium. -from Authors

  5. Automatic measuring device for atomic oxygen concentrations (1962); Dispositif de mesure automatique de concentrations d'oxygene atomique (1962)

    Energy Technology Data Exchange (ETDEWEB)

    Weill, J; Deiss, M; Mercier, R [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1962-07-01

    Within the framework of the activities of the Autonomous Reactor Electronics Section we have developed a device, which renders automatic one type of measurement carried out in the Physical Chemistry Department at the Saclay Research Centre. We define here: - the physico-chemical principle of the apparatus which is adapted to the measurement of atomic oxygen concentrations; - the physical principle of the automatic measurement; - the properties, performance, constitution, use and maintenance of the automatic measurement device. It is concluded that the principle of the automatic device, whose tests have confirmed the estimation of the theoretical performance, could usefully be adapted to other types of measurement. (authors) [French] Dans le cadre des activites de la Section Autonome d'Electronique des Reacteurs, il a ete realise et mis au point un dispositif permettant de rendre automatique un type de mesures effectuees au Departement de Physico-Chimie du C.E.N. SACLAY. On definit ici: - le principe physico-chimique de l'appareillage, adapte a la mesure de concentrations de l'oxygene atomique; - le principe physique de la mesure automatique; - les qualites, performances, constitution, utilisation, et maintenance du dispositif de mesure automatique. Il est porte en conclusion, que le principe du dispositif automatique realise, dont les essais ont sensiblement confirme l'evaluation des performances theoriques, pourrait etre utilement adapte a d'autres types de mesures courantes. (auteurs)

  6. Body mass index and blood pressure measurement during pregnancy.

    LENUS (Irish Health Repository)

    Hogan, Jennifer L

    2012-02-01

    OBJECTIVE: The accurate measurement of blood pressure requires the use of a large cuff in subjects with a high mid-arm circumference (MAC). This prospective study examined the need for a large cuff during pregnancy and its correlation with maternal obesity. METHODS: Maternal body mass index (BMI), fat mass, and MAC were measured. RESULTS: Of 179 women studied, 15.6% were obese. With a BMI of level 1 obesity, 44% needed a large cuff and with a BMI of level 2 obesity 100% needed a large cuff. CONCLUSION: All women booking for antenatal care should have their MAC measured to avoid the overdiagnosis of pregnancy hypertension.

  7. Quantitative measurement of cerebral oxygen extraction fraction using MRI in patients with MELAS.

    Directory of Open Access Journals (Sweden)

    Lei Yu

    Full Text Available OBJECTIVE: To quantify the cerebral OEF at different phases of stroke-like episodes in patients with mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS by using MRI. METHODS: We recruited 32 patients with MELAS confirmed by gene analysis. Conventional MRI scanning, as well as functional MRI including arterial spin labeling and oxygen extraction fraction imaging, was undertaken to obtain the pathological and metabolic information of the brains at different stages of stroke-like episodes in patients. A total of 16 MRI examinations at the acute and subacute phase and 19 examinations at the interictal phase were performed. In addition, 24 healthy volunteers were recruited for control subjects. Six regions of interest were placed in the anterior, middle, and posterior parts of the bilateral hemispheres to measure the OEF of the brain or the lesions. RESULTS: OEF was reduced significantly in brains of patients at both the acute and subacute phase (0.266 ± 0.026 and at the interictal phase (0.295 ± 0.009, compared with normal controls (0.316 ± 0.025. In the brains at the acute and subacute phase of the episode, 13 ROIs were prescribed on the stroke-like lesions, which showed decreased OEF compared with the contralateral spared brain regions. Increased blood flow was revealed in the stroke-like lesions at the acute and subacute phase, which was confined to the lesions. CONCLUSION: MRI can quantitatively show changes in OEF at different phases of stroke-like episodes. The utilization of oxygen in the brain seems to be reduced more severely after the onset of episodes in MELAS, especially for those brain tissues involved in the episodes.

  8. Effect of acute and delayed hyperbaric oxygen therapy on cyanide whole blood levels during acute cyanide intoxication

    DEFF Research Database (Denmark)

    Lawson-Smith, P; Jansen, E C; Hilsted, Linda Maria

    2011-01-01

    and the subsequent formation of cyanocobalamin measured by a spectrophotometer. Results showed that whole-blood-cyanide concentration in Group 1 controls and acute HBO2 initially rose and then fell towards zero. In rats treated with delayed HBO2, the reduction in whole-blood-cyanide concentration was significantly...

  9. The relationship between the cerebral blood flow, oxygen consumption and glucose metabolism in primary degenerative dementia

    Energy Technology Data Exchange (ETDEWEB)

    Kuwabara, Yasuo; Ichiya, Yuichi; Ichimiya, Atsushi; Sasaki, Masayuki; Akashi, Yuko; Yoshida, Tsuyoshi; Fukumura, Toshimitsu; Masada, Kouji [Kyushu Univ., Fukuoka (Japan). Faculty of Medicine

    1995-03-01

    The CBF, CMRO{sub 2} and CMRGlu were measured in patients with primary degenerative dementia including 5 patients with dementia of Alzheimer`s type and 4 patients with Pick`s disease, and then the correlation between the cerebral blood flow and energy metabolism was evaluated. The control subjects consisted of 5 age-matched normal volunteers. The CBF, CMRO{sub 2} and CMRGlu decreased in the bilateral frontal, temporal and parietal regions in the patients with Alzheimer`s dementia, while they decreased in the bilateral frontal and temporal regions in the patients with Pick`s disease. Both the CBF and CMRO{sub 2} were closely correlated with each other. However, the CMRGlu was more severely impaired than the CBF or CMRO{sub 2} in both pathological conditions. These results suggested that CMRGlu began to decrease before the reduction of the aerobic metabolism and thus measuring the CMRGlu is considered to be the most sensitive method for detecting abnormal regions in primary degenerative dementia. (author).

  10. Measurements of Positively Charged Ions in Premixed Methane-Oxygen Atmospheric Flames

    KAUST Repository

    Alquaity, Awad; Han, Jie; Chahine, May; Selim, Hatem; Belhi, Memdouh; Sarathy, Mani; Bisetti, Fabrizio; Farooq, Aamir

    2016-01-01

    chemistry models are needed to understand and predict the effect of external electric fields on combustion plasmas. In this work, a molecular beam mass spectrometer (MBMS) is utilized to measure ion concentration profiles in premixed methane–oxygen argon

  11. Supplementary Material for: Measurements of Positively Charged Ions in Premixed Methane-Oxygen Atmospheric Flames

    KAUST Repository

    Alquaity, Awad B. S.; Han, Jie; Chahine, May; Selim, Hatem; Belhi, Memdouh; Sarathy, Mani; Bisetti, Fabrizio; Farooq, Aamir

    2017-01-01

    chemistry models are needed to understand and predict the effect of external electric fields on combustion plasmas. In this work, a molecular beam mass spectrometer (MBMS) is utilized to measure ion concentration profiles in premixed methane–oxygen argon

  12. A new method to measure and model dynamic oxygen microdistributions in moving biofilms.

    Science.gov (United States)

    Wang, Jian-Hui; Chen, You-Peng; Dong, Yang; Wang, Xi-Xi; Guo, Jin-Song; Shen, Yu; Yan, Peng; Ma, Teng-Fei; Sun, Xiu-Qian; Fang, Fang; Wang, Jing

    2017-10-01

    Biofilms in natural environments offer a superior solution to mitigate water pollution. Artificially intensified biofilm reactors represented by rotating biological contactors (RBCs) are widely applied and studied. Understanding the oxygen transfer process in biofilms is an important aspect of these studies, and describing this process in moving biofilms (such as biofilms in RBCs) is a particular challenge. Oxygen transfer in RBCs behaves differently than in other biological reactors due to the special oxygen supply mode that results from alternate exposure of the biofilm to wastewater and air. The study of oxygen transfer in biofilms is indispensable for understanding biodegradation in RBCs. However, the mechanisms are still not well known due to a lack of effective tools to dynamically analyze oxygen diffusion, reaction, and microdistribution in biofilms. A new experimental device, the Oxygen Transfer Modeling Device (OTMD), was designed and manufactured for this purpose, and a mathematical model was developed to model oxygen transfer in biofilm produced by an RBC. This device allowed the simulation of the local environment around the biofilm during normal RBC operation, and oxygen concentrations varying with time and depth in biofilm were measured using an oxygen microelectrode. The experimental data conformed well to the model description, indicating that the OTMD and the model were stable and reliable. Moreover, the OTMD offered a flexible approach to study the impact of a single-factor on oxygen transfer in moving biofilms. In situ environment of biofilm in an RBC was simulated, and dynamic oxygen microdistributions in the biofilm were measured and well fitted to the built model description. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Cutaneous respirometry by dynamic measurement of mitochondrial oxygen tension for monitoring mitochondrial function in vivo.

    Science.gov (United States)

    Harms, Floor A; Voorbeijtel, Wilhelmina J; Bodmer, Sander I A; Raat, Nicolaas J H; Mik, Egbert G

    2013-09-01

    Progress in diagnosis and treatment of mitochondrial dysfunction in chronic and acute disease could greatly benefit from techniques for monitoring of mitochondrial function in vivo. In this study we demonstrate the feasibility of in vivo respirometry in skin. Mitochondrial oxygen measurements by means of oxygen-dependent delayed fluorescence of protoporphyrin IX are shown to provide a robust basis for measurement of local oxygen disappearance rate (ODR). The fundamental principles behind the technology are described, together with an analysis method for retrievel of respirometry data. The feasibility and reproducibility of this clinically useful approach are demonstrated in a series of rats. Copyright © 2012 Elsevier B.V. All rights reserved.

  14. Oxygen optodes as fast sensors for eddy correlation measurements in aquatic systems

    DEFF Research Database (Denmark)

    Chipman, Lindsay; Huettel, Markus; Berg, Peter

    2012-01-01

    The aquatic eddy-correlation technique can be used to noninvasively determine the oxygen exchange across the sediment-water interface by analyzing the covariance of vertical flow velocity and oxygen concentration in a small measuring volume above the sea bed. The method requires fast sensors...... that combine the advantages of noninvasive measurements and integration of fluxes over a large footprint area, using a relatively rugged and less expensive sensor....

  15. The measurement of blood speed in the pulmonary artery trunk

    Energy Technology Data Exchange (ETDEWEB)

    Saro, J P; Bula-Cruz, J [UTAD - 5000 Vila Real (Spain); Rafael, J A [Dep. Electronica e Telecomunicacoes da Univ. de Aveiro - 3800 Aveiro (Spain); Botelho, M F; Lima, J P [IBILI - Faculdade de Medicina da Univ. de Coimbra - 3000 Coimbra (Spain)

    1999-12-31

    The paper describes a non invasive methodology for the measurement of blood speed in the pulmonary artery trunk. The methodology has been tested with a moving radioactive tracer (nuclear medicine). An image processing technique is proposed, for detection and analysis of a moving object with variable shape and intensity over time (radioactive bolus). Experiments on the application of the technique in nuclear medicine are critically analysed. (authors) 9 refs., 7 figs.

  16. Ultrasonic Doppler measurement of renal artery blood flow

    Science.gov (United States)

    Freund, W. R.; Meindl, J. D.

    1975-01-01

    An extensive evaluation of the practical and theoretical limitations encountered in the use of totally implantable CW Doppler flowmeters is provided. Theoretical analyses, computer models, in-vitro and in-vivo calibration studies describe the sources and magnitudes of potential errors in the measurement of blood flow through the renal artery, as well as larger vessels in the circulatory system. The evaluation of new flowmeter/transducer systems and their use in physiological investigations is reported.

  17. Transcutaneous Measurement of Blood Analyte Concentration Using Raman Spectroscopy

    Science.gov (United States)

    Barman, Ishan; Singh, Gajendra P.; Dasari, Ramachandra R.; Feld, Michael S.

    2008-11-01

    Diabetes mellitus is a chronic disorder, affecting nearly 200 million people worldwide. Acute complications, such as hypoglycemia, cardiovascular disease and retinal damage, may occur if the disease is not adequately controlled. As diabetes has no known cure, tight control of glucose levels is critical for the prevention of such complications. Given the necessity for regular monitoring of blood glucose, development of non-invasive glucose detection devices is essential to improve the quality of life in diabetic patients. The commercially available glucose sensors measure the interstitial fluid glucose by electrochemical detection. However, these sensors have severe limitations, primarily related to their invasive nature and lack of stability. This necessitates the development of a truly non-invasive glucose detection technique. NIR Raman Spectroscopy, which combines the substantial penetration depth of NIR light with the excellent chemical specificity of Raman spectroscopy, provides an excellent tool to meet the challenges involved. Additionally, it enables simultaneous determination of multiple blood analytes. Our laboratory has pioneered the use of Raman spectroscopy for blood analytes' detection in biological media. The preliminary success of our non-invasive glucose measurements both in vitro (such as in serum and blood) and in vivo has provided the foundation for the development of feasible clinical systems. However, successful application of this technology still faces a few hurdles, highlighted by the problems of tissue luminescence and selection of appropriate reference concentration. In this article we explore possible avenues to overcome these challenges so that prospective prediction accuracy of blood analytes can be brought to clinically acceptable levels.

  18. Multi Frequency Phase Fluorimetry (MFPF) for Oxygen Partial Pressure Measurement: Ex Vivo Validation by Polarographic Clark-Type Electrode

    Science.gov (United States)

    Boehme, Stefan; Duenges, Bastian; Klein, Klaus U.; Hartwich, Volker; Mayr, Beate; Consiglio, Jolanda; Baumgardner, James E.; Markstaller, Klaus; Basciani, Reto; Vogt, Andreas

    2013-01-01

    Background Measurement of partial pressure of oxygen (PO2) at high temporal resolution remains a technological challenge. This study introduces a novel PO2 sensing technology based on Multi-Frequency Phase Fluorimetry (MFPF). The aim was to validate MFPF against polarographic Clark-type electrode (CTE) PO2 measurements. Methodology/Principal Findings MFPF technology was first investigated in N = 8 anaesthetised pigs at FIO2 of 0.21, 0.4, 0.6, 0.8 and 1.0. At each FIO2 level, blood samples were withdrawn and PO2 was measured in vitro with MFPF using two FOXY-AL300 probes immediately followed by CTE measurement. Secondly, MFPF-PO2 readings were compared to CTE in an artificial circulatory setup (human packed red blood cells, haematocrit of 30%). The impacts of temperature (20, 30, 40°C) and blood flow (0.8, 1.6, 2.4, 3.2, 4.0 L min−1) on MFPF-PO2 measurements were assessed. MFPF response time in the gas- and blood-phase was determined. Porcine MFPF-PO2 ranged from 63 to 749 mmHg; the corresponding CTE samples from 43 to 712 mmHg. Linear regression: CTE = 15.59+1.18*MFPF (R2 = 0.93; PPO2 ranged from 20 to 567 mmHg and CTE samples from 11 to 575 mmHg. Linear regression: CTE = −8.73+1.05*MFPF (R2 = 0.99; PPO2 due to variations of temperature were less than 6 mmHg (range 0–140 mmHg) and less than 35 mmHg (range 140–750 mmHg); differences due to variations in blood flow were less than 15 mmHg (all P-values>0.05). MFPF response-time (monoexponential) was 1.48±0.26 s for the gas-phase and 1.51±0.20 s for the blood-phase. Conclusions/Significance MFPF-derived PO2 readings were reproducible and showed excellent correlation and good agreement with Clark-type electrode-based PO2 measurements. There was no relevant impact of temperature and blood flow upon MFPF-PO2 measurements. The response time of the MFPF FOXY-AL300 probe was adequate for real-time sensing in the blood phase. PMID:23565259

  19. Validation of a novel device to objectively measure adherence to long-term oxygen therapy

    Directory of Open Access Journals (Sweden)

    Sun-Kai V Lin

    2008-10-01

    Full Text Available Sun-Kai V Lin1, Daniel K Bogen1, Samuel T Kuna2,31Department of Bioengineering; 2Department of Medicine, Pulmonary, Allergy and Critical Care Division, and Center for Sleep and Respiratory Neurobiology, University of Pennsylvania, Pennsylvania, USA; 3Department of Medicine, Philadelphia Veterans Affairs Medical Center Philadelphia, Pennsylvania, USARationale: We have developed a novel oxygen adherence monitor that objectively measures patient use of long-term oxygen therapy. The monitor attaches to the oxygen source and detects whether or not the patient is wearing the nasal cannula.Objective: The study’s purpose was to validate the monitor’s performance in patients with chronic obstructive pulmonary disease during wakefulness and sleep.Methods: Ten adult males with stable chronic obstructive pulmonary disease (mean ± SD FEV1 37.7 ± 14.9% of predicted on long-term continuous oxygen therapy were tested in a sleep laboratory over a 12–13 hour period that included an overnight polysomnogram.Measurements: The monitor’s measurements were obtained at 4-minute intervals and compared to actual oxygen use determined by review of time-synchronized video recordings.Main results: The monitor made 1504/1888 (79.7% correct detections (unprocessed data across all participants: 957/1,118 (85.6% correct detections during wakefulness and 546/770 (70.9% during sleep. All errors were false negatives, ie, the monitor failed to detect that the participant was actually wearing the cannula. Application of a majority-vote filter to the raw data improved overall detection accuracy to 84.9%.Conclusions: The results demonstrate the monitor’s ability to objectively measure whether or not men with chronic obstructive pulmonary disease are receiving their oxygen treatment. The ability to objectively measure oxygen delivery, rather than oxygen expended, may help improve the management of patients on long-term oxygen therapy.Keywords: chronic obstructive pulmonary

  20. Influence of glutamate-evoked pain and sustained elevated muscle activity on blood oxygenation in the human masseter muscle.

    Science.gov (United States)

    Suzuki, Shunichi; Arima, Taro; Kitagawa, Yoshimasa; Svensson, Peter; Castrillon, Eduardo

    2017-12-01

    This study aimed to investigate the effect of glutamate-evoked masseter muscle pain on intramuscular oxygenation during rest and sustained elevated muscle activity (SEMA). Seventeen healthy individuals participated in two sessions in which they were injected with glutamate and saline in random order. Each session was divided into three, 10-min periods. During the first (period 1) and the last (period 3) 10-min periods, participants performed five intercalated 1-min bouts of masseter SEMA with 1-min periods of 'rest'. At onset of the second 10-min period, glutamate (0.5 ml, 1 M; Ajinomoto, Tokyo, Japan) or isotonic saline (0.5 ml; 0.9%) was injected into the masseter muscle and the participants kept the muscle relaxed in a resting position for 10 min (period 2). The hemodynamic characteristics of the masseter muscle were recorded simultaneously during the experiment by a laser blood-oxygenation monitor. The results demonstrated that glutamate injections caused significant levels of self-reported pain in the masseter muscle; however, this nociceptive input did not have robust effects on intramuscular oxygenation during rest or SEMA tasks. Interestingly, these findings suggest an uncoupling between acute nociceptive activity and hemodynamic parameters in both resting and low-level active jaw muscles. Further studies are needed to explore the pathophysiological significance of blood-flow changes for persistent jaw-muscle pain conditions. © 2017 Eur J Oral Sci.

  1. Seasonal changes in blood oxygen transport and acid-base status in the tegu lizard, Tupinambis merianae.

    Science.gov (United States)

    Andrade, Denis V; Brito, Simone P; Toledo, Luís Felipe; Abe, Augusto S

    2004-05-20

    Oxygen-binding properties, blood gases, and acid-base parameters were studied in tegu lizards, Tupinambis merianae, at different seasons and temperatures. Independent of temperature and pH, blood oxygen affinity was higher in dormant lizards than in those active during the summer. Haematocrit (Hct) and hemoglobin content ([Hb]) were greater in active lizards resulting in a higher oxygen-carrying capacity. Nucleoside triphosphate content ([NTP]) was reduced during dormancy, but the ratio between [NTP] and [Hb] remained unchanged. Dormancy was accompanied by an increase in plasma bicarbonate ([HCO-(3)]pl) and an elevation of arterial CO2 partial pressure (PaCO2) and CO2 content in the plasma (CplCO2). These changes in acid-base parameters persist over a broad range of body temperatures. In vivo, arterial O2 partial pressure (PaO2) and O2 content (CaO2) were not affected by season and tended to increase with temperature. Arterial pH (pHa) of dormant animals is reduced compared to active lizards at body temperatures below 15 degrees C, while no significant difference was noticed at higher temperatures. Copyright 2003 Elsevier B.V.

  2. Association between regional quadriceps oxygenation and blood oxygen saturation during normoxic one-legged dynamic knee extension

    DEFF Research Database (Denmark)

    Esaki, Kazuki; Hamaoka, Takafumi; Rådegran, Göran

    2005-01-01

    -peak. There was a significant correlation between O(2-NIRS) and S(fv)o2(VL-p: r (2) = 0.62, VL-d: r2 = 0.35, RF-p: r2 = 0.62, with a moderate variation among individuals at each site; residual values = 4.83 - 11.75). These data indicate that NIRS measurement provides a reflection of S(fv)o2 during 20-60% WR-peak of normoxic 1L-KEE....

  3. A pitfall in the measurement of arterial blood pressure in the ischaemic limb during elevation

    DEFF Research Database (Denmark)

    Bülow, J; Jelnes, Rolf

    1987-01-01

    In order to evaluate if elevation of the ischaemic limb above heart level is an alternative to the conventionally applied method with external counterpressure for estimation of skin perfusion pressure, femoral and popliteal artery pressures were measured directly in eight patients with occlusion...... of the superficial femoral artery. The measurements were done in the horizontal position and during elevation of the calf above heart level. During elevation relative blood flow, measured by arterio-venous oxygen saturation differences, decreased compared with the horizontal position. In contrast the popliteal...... arterial pressure decreased only by 20% of the value expected from the degree of elevation of the calf above the level of the heart. Thus, it could be calculated that calf vascular resistance increased two- to three-fold on average during elevation. Four patients were reexamined with the venous pressure...

  4. Membrane culture and reduced oxygen tension enhances cartilage matrix formation from equine cord blood mesenchymal stromal cells in vitro.

    Science.gov (United States)

    Co, C; Vickaryous, M K; Koch, T G

    2014-03-01

    Ongoing research is aimed at increasing cartilage tissue yield and quality from multipotent mesenchymal stromal cells (MSC) for the purpose of treating cartilage damage in horses. Low oxygen culture has been shown to enhance chondrogenesis, and novel membrane culture has been proposed to increase tissue yield and homogeneity. The objective of this study was to evaluate and compare the effect of reduced oxygen and membrane culture during in vitro chondrogenesis of equine cord blood (CB) MSC. CB-MSC (n = 5 foals) were expanded at 21% oxygen prior to 3-week differentiation in membrane or pellet culture at 5% and 21% oxygen. Assessment included histological examination (H&E, toluidine Blue, immunohistochemistry (IHC) for collagen type I and II), protein quantification by hydroxyproline assay and dimethylmethylene assay, and mRNA analysis for collagen IA1, collagen IIA1, collagen XA1, HIF1α and Sox9. Among treatment groups, 5% membrane culture produced neocartilage most closely resembling hyaline cartilage. Membrane culture resulted in increased wet mass, homogenous matrix morphology and an increase in total collagen content, while 5% oxygen culture resulted in higher GAG and type II collagen content. No significant differences were observed for mRNA analysis. Membrane culture at 5% oxygen produces a comparatively larger amount of higher quality neocartilage. Matrix homogeneity is attributed to a uniform diffusion gradient and reduced surface tension. Membrane culture holds promise for scale-up for therapeutic purposes, for cellular preconditioning prior to cytotherapeutic applications, and for modeling system for gas-dependent chondrogenic differentiation studies. Crown Copyright © 2014. Published by Elsevier Ltd. All rights reserved.

  5. Regional cerebral blood flow measurement using a scintillation camera

    International Nuclear Information System (INIS)

    Heiss, W.D.

    1979-01-01

    A scintillation camera connected to auxillary equipment with off-line data processing or connected to an on-line dedicated computer system permits measurement of hemispheric and regional cerebral blood flow. Reliable flow values are obtained from regions limited in size by spatial resolution and the count rates achieved. Flow measurements obtained with the camera are able to resolve inhomogeneities of cerebral circulation in normal subjects. In a variety of clinical conditions, the localization, severity and extent of flow alterations are shown. Results of flow measurements in individual cases elucidate the pathogenesis of neurologic deficits, quantify the damage to the brain, indicate therapeutic measures of potential value and permit an estimation of the further clinical course. With restricted spatial resolution, flow measurements after intravenous 133 Xe injection are also feasible

  6. LUMOS - A Sensitive and Reliable Optode System for Measuring Dissolved Oxygen in the Nanomolar Range

    DEFF Research Database (Denmark)

    Lehner, Philipp; Larndorfer, Christoph; Garcia-Robledo, Emilio

    2015-01-01

    Most commercially available optical oxygen sensors target the measuring range of 300 to 2 mu mol L-1. However these are not suitable for investigating the nanomolar range which is relevant for many important environmental situations. We therefore developed a miniaturized phase fluorimeter based...... for read out of less sensitive optical oxygen sensors based on the same or similar indicator dyes, for example for monitoring oxygen at physiological conditions. The presented sensor system exhibits lower noise, higher resolution and higher sensitivity than the electrochemical STOX sensor previously used...... measurement system called the LUMOS (Luminescence Measuring Oxygen Sensor). It consists of a readout device and specialized "sensing chemistry" that relies on commercially available components. The sensor material is based on palladium(II)-5,10,15,20-tetrakis-(2,3,4,5,6-pentafluorphenyl)-porphyrin embedded...

  7. Prospective blood pressure measurement in renal transplant recipients.

    Science.gov (United States)

    David, V G; Yadav, B; Jeyaseelan, L; Deborah, M N; Jacob, S; Alexander, S; Varughese, S; John, G T

    2014-05-01

    Blood pressure (BP) control at home is difficult when managed only with office blood pressure monitoring (OBPM). In this prospective study, the reliability of BP measurements in renal transplant patients with OBPM and home blood pressure monitoring (HBPM) was compared with ambulatory blood pressure monitoring (ABPM) as the gold standard. Adult patients who had living-related renal transplantation from March 2007 to February 2008 had BP measured by two methods; OBPM and ABPM at pretransplantation, 2(nd), 4(th), 6(th), and 9(th) months and all the three methods: OBPM, ABPM, and HBPM at 6 months after transplantation. A total of 49 patients, age 35 ± 11 years, on prednisolone, tacrolimus, and mycophenolate were evaluated. A total of 39 were males (79.6%). Systolic BP (SBP) and diastolic BP (DBP) measured by OBPM were higher than HBPM when compared with ABPM. When assessed using OBPM and awake ABPM, both SBP and DBP were significantly overestimated by OBPM with mean difference of 3-12 mm Hg by office SBP and 6-8 mm Hg for office DBP. When HBPM was compared with mean ABPM at 6 months both the SBP and DBP were overestimated by and 7 mm Hg respectively. At 6 months post transplantation, when compared with ABPM, OBPM was more specific than HBPM in diagnosing hypertension (98% specificity, Kappa: 0.88 vs. 89% specificity, Kappa: 0.71). HBPM was superior to OBPM in identifying patients achieving goal BP (89% specificity, Kappa: 0.71 vs. 50% specificity Kappa: 0.54). In the absence of a gold standard for comparison the latent class model analysis still showed that ABPM was the best tool for diagnosing hypertension and monitoring patients reaching targeted control. OBPM remains an important tool for the diagnosis and management of hypertension in renal transplant recipients. HBPM and ABPM could be used to achieve BP control.

  8. Prospective blood pressure measurement in renal transplant recipients

    Directory of Open Access Journals (Sweden)

    V G David

    2014-01-01

    Full Text Available Blood pressure (BP control at home is difficult when managed only with office blood pressure monitoring (OBPM. In this prospective study, the reliability of BP measurements in renal transplant patients with OBPM and home blood pressure monitoring (HBPM was compared with ambulatory blood pressure monitoring (ABPM as the gold standard. Adult patients who had living-related renal transplantation from March 2007 to February 2008 had BP measured by two methods; OBPM and ABPM at pretransplantation, 2 nd , 4 th , 6 th , and 9 th months and all the three methods : OBPM, ABPM, and HBPM at 6 months after transplantation. A total of 49 patients, age 35 ± 11 years, on prednisolone, tacrolimus, and mycophenolate were evaluated. A total of 39 were males (79.6%. Systolic BP (SBP and diastolic BP (DBP measured by OBPM were higher than HBPM when compared with ABPM. When assessed using OBPM and awake ABPM, both SBP and DBP were significantly overestimated by OBPM with mean difference of 3-12 mm Hg by office SBP and 6-8 mm Hg for office DBP. When HBPM was compared with mean ABPM at 6 months both the SBP and DBP were overestimated by and 7 mm Hg respectively. At 6 months post transplantation, when compared with ABPM, OBPM was more specific than HBPM in diagnosing hypertension (98% specificity, Kappa : 0.88 vs. 89% specificity, Kappa : 0.71. HBPM was superior to OBPM in identifying patients achieving goal BP (89% specificity, Kappa : 0.71 vs. 50% specificity Kappa : 0.54. In the absence of a gold standard for comparison the latent class model analysis still showed that ABPM was the best tool for diagnosing hypertension and monitoring patients reaching targeted control. OBPM remains an important tool for the diagnosis and management of hypertension in renal transplant recipients. HBPM and ABPM could be used to achieve BP control.

  9. Cerebral Metabolic Rate of Oxygen (CMRO2 ) Mapping by Combining Quantitative Susceptibility Mapping (QSM) and Quantitative Blood Oxygenation Level-Dependent Imaging (qBOLD).

    Science.gov (United States)

    Cho, Junghun; Kee, Youngwook; Spincemaille, Pascal; Nguyen, Thanh D; Zhang, Jingwei; Gupta, Ajay; Zhang, Shun; Wang, Yi

    2018-03-07

    To map the cerebral metabolic rate of oxygen (CMRO 2 ) by estimating the oxygen extraction fraction (OEF) from gradient echo imaging (GRE) using phase and magnitude of the GRE data. 3D multi-echo gradient echo imaging and perfusion imaging with arterial spin labeling were performed in 11 healthy subjects. CMRO 2 and OEF maps were reconstructed by joint quantitative susceptibility mapping (QSM) to process GRE phases and quantitative blood oxygen level-dependent (qBOLD) modeling to process GRE magnitudes. Comparisons with QSM and qBOLD alone were performed using ROI analysis, paired t-tests, and Bland-Altman plot. The average CMRO 2 value in cortical gray matter across subjects were 140.4 ± 14.9, 134.1 ± 12.5, and 184.6 ± 17.9 μmol/100 g/min, with corresponding OEFs of 30.9 ± 3.4%, 30.0 ± 1.8%, and 40.9 ± 2.4% for methods based on QSM, qBOLD, and QSM+qBOLD, respectively. QSM+qBOLD provided the highest CMRO 2 contrast between gray and white matter, more uniform OEF than QSM, and less noisy OEF than qBOLD. Quantitative CMRO 2 mapping that fits the entire complex GRE data is feasible by combining QSM analysis of phase and qBOLD analysis of magnitude. © 2018 International Society for Magnetic Resonance in Medicine.

  10. High impact of uranyl ions on carrying-releasing oxygen capability of hemoglobin-based blood substitutes

    Energy Technology Data Exchange (ETDEWEB)

    Duan, Li; Du, Lili; Liu, Wenyuan; Liu, Zhichao [Northwest Institute of Nuclear Technology, Xi' an, Shaanxi (China); Jia, Yi; Li, Junbai [Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Colloid Interface and Chemical Thermodynamics, Institute of Chemistry, Chinese Academy of Sciences, Beijing (China)

    2015-01-07

    The effect of radioactive UO{sub 2}{sup 2+} on the oxygen-transporting capability of hemoglobin-based oxygen carriers has been investigated in vitro. The hemoglobin (Hb) microspheres fabricated by the porous template covalent layer-by-layer (LbL) assembly were utilized as artificial oxygen carriers and blood substitutes. Magnetic nanoparticles of iron oxide (Fe{sub 3}O{sub 4}) were loaded in porous CaCO{sub 3} particles for magnetically assisted chemical separation (MACS). Through the adsorption spectrum of magnetic Hb microspheres after adsorbing UO{sub 2}{sup 2+}, it was found that UO{sub 2}{sup 2+} was highly loaded in the magnetic Hb microspheres, and it shows that the presence of UO{sub 2}{sup 2+} in vivo destroys the structure and oxygen-transporting capability of Hb microspheres. In view of the high adsorption capacity of UO{sub 2}{sup 2+}, the as-assembled magnetic Hb microspheres can be considered as a novel, highly effective adsorbent for removing metal toxins from radiation-contaminated bodies, or from nuclear-power reactor effluent before discharge into the environment. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  11. Assessment of early renal allograft dysfunction with blood oxygenation level-dependent MRI and diffusion-weighted imaging

    Energy Technology Data Exchange (ETDEWEB)

    Park, Sung Yoon [Department of Radiology and Research Institute of Radiological Science, Severance Hospital, Yonsei University College of Medicine, Seoul (Korea, Republic of); Kim, Chan Kyo, E-mail: chankyokim@skku.edu [Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul (Korea, Republic of); Park, Byung Kwan [Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul (Korea, Republic of); Kim, Sung Ju; Lee, Sanghoon [Department of Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul (Korea, Republic of); Huh, Wooseong [Department of Nephrology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul (Korea, Republic of)

    2014-12-15

    Highlights: • R2* and ADC in renal allografts are moderately correlated with eGFR. • R2* and ADC are lower in early allograft dysfunction than normal allograft function. • No significant difference between AR and ATN was found in both R2* and ADC. - Abstract: Purpose: To investigate blood oxygenation level-dependent (BOLD) MRI and diffusion-weighted imaging (DWI) at 3 T for assessment of early renal allograft dysfunction. Materials and methods: 34 patients with a renal allograft (early dysfunction, 24; normal, 10) were prospectively enrolled. BOLD MRI and DWI were performed at 3 T. R2* and apparent diffusion coefficient (ADC) values were measured in cortex and medulla of the allografts. Correlation between R2* or ADC values and estimated glomerular filtration rate (eGFR) was investigated. R2* or ADC values were compared among acute rejection (AR), acute tubular necrosis (ATN) and normal function. Results: In all renal allografts, cortical or medullary R2* and ADC values were moderately correlated with eGFR (P < 0.05). Early dysfunction group showed lower R2* and ADC values than normal function group (P < 0.05). AR or ATN had lower R2* values than normal allografts (P < 0.05), and ARs had lower cortical ADC values than normal allografts (P < 0.05). No significant difference of R2* or ADC values was found between AR and ATN (P > 0.05). Conclusion: BOLD MRI and DWI at 3 T may demonstrate early functional state of renal allografts, but may be limited in characterizing a cause of early renal allograft dysfunction. Further studies are needed.

  12. Correlation between quantitative EEG and cerebral blood flow and oxygen metabolism in patients with dementia of Alzheimer type

    International Nuclear Information System (INIS)

    Kudoh, Masako; Takahashi, Satoshi; Yonezawa, Hisashi

    1997-01-01

    Quantitative scalp EEG and cerebral blood flow (CBF) and oxygen metabolism (CMRO 2 ) measured by the steady-state 15 O technique and positron emission tomography were studied in 19 patients with mild to moderate dementia of Alzheimer type (DAT) and age-matched controls (EEG=19, PET=6). Scalp electrodes were placed according to the international 10-20 method except for Cz, T3, and T4. To evaluate the relative changes in power for each frequency band between the two groups, the percentage power fraction (percentage power for each frequency band at a site compared to the total power at that site; %delta for 2.0-3.8 Hz, %theta for 4.0-7.8 Hz, %alpha for 8.0-12.8 Hz, %beta for 13.0-25.4 Hz) was calculated. Compared with controls, DAT patients showed a significant decrease in %alpha, while significant increases in %theta at all electrodes, and significant increases in %delta at the temporal, parietal and occipital electrodes were observed. The patient group displayed a significant decrease in rCBF and rCMRO 2 in the parietal, temporal and frontal cortices, but the reduction in rCMRO 2 was less remarkable than that of rCBF. %Theta at P3, O1 and O2 showed a significant negative correlation with rCBF, and %theta at P3, O1showed a significant negative correlation with rCMRO 2 . %Delta at P3, P4 and T5 was significantly negatively correlated with rCBF in the corresponding regions, and %alpha at almost all the electrodes (except O1, F3, P3) was significantly positively correlated with rCBF in the corresponding regions. %Delta and %alpha did not show any significant correlation with rCMRO 2 . (author)

  13. Blood oxygenation level dependent signal and neuronal adaptation to optogenetic and sensory stimulation in somatosensory cortex in awake animals.

    Science.gov (United States)

    Aksenov, Daniil P; Li, Limin; Miller, Michael J; Wyrwicz, Alice M

    2016-11-01

    The adaptation of neuronal responses to stimulation, in which a peak transient response is followed by a sustained plateau, has been well-studied. The blood oxygenation level dependent (BOLD) functional magnetic resonance imaging (fMRI) signal has also been shown to exhibit adaptation on a longer time scale. However, some regions such as the visual and auditory cortices exhibit significant BOLD adaptation, whereas other such as the whisker barrel cortex may not adapt. In the sensory cortex a combination of thalamic inputs and intracortical activity drives hemodynamic changes, although the relative contributions of these components are not entirely understood. The aim of this study is to assess the role of thalamic inputs vs. intracortical processing in shaping BOLD adaptation during stimulation in the somatosensory cortex. Using simultaneous fMRI and electrophysiology in awake rabbits, we measured BOLD, local field potentials (LFPs), single- and multi-unit activity in the cortex during whisker and optogenetic stimulation. This design allowed us to compare BOLD and haemodynamic responses during activation of the normal thalamocortical sensory pathway (i.e., both inputs and intracortical activity) vs. the direct optical activation of intracortical circuitry alone. Our findings show that whereas LFP and multi-unit (MUA) responses adapted, neither optogenetic nor sensory stimulation produced significant BOLD adaptation. We observed for both paradigms a variety of excitatory and inhibitory single unit responses. We conclude that sensory feed-forward thalamic inputs are not primarily responsible for shaping BOLD adaptation to stimuli; but the single-unit results point to a role in this behaviour for specific excitatory and inhibitory neuronal sub-populations, which may not correlate with aggregate neuronal activity. © 2016 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

  14. The effects of anticholinergic drugs on regional cerebral blood flow, and oxygen metabolism in previously untreated patients with Parkinson's disease

    International Nuclear Information System (INIS)

    Obara, Satoko; Takahashi, Satoshi; Yonezawa, Hisashi; Sato, Yoshitomo

    1998-01-01

    Regional cerebral blood flow (rCBF) and oxygen metabolism (rCMRO 2 ) were measured using the steady-state 15 O technique and positron emission tomography (PET) in six previously untreated patients with Parkinson's disease before and after trihexyphenidyl (THP) treatment. The patients comprised of 4 men and 2 women with Hoehn-Yahr stage II-III. Their ages at the onset of the study ranged from 46 to 57 years (mean±SD, 51.8±3.7) and the duration of the illness ranged from 10 to 48 months (mean±SD, 28.8±15.5). The PET study, assessments of the disability and cognitive function were undergone twice. The first time assessments were done was when the patients were not receiving any drugs, and the second time was one to three months after administration of 6 mg THP. All patients showed clinical improvement after THP treatment. The mean disability score of Unified Parkinson's Disease Rating Scale decreased from 35.1 (SD±11.3) to 25.7 (SD±11.6). The cognitive function assessed by Hasegawa's dementia rating scale-revised, Mini-Mental State Examination, Wechsler Adult Intelligence Scale-Revised, and Wechsler Memory Scale-Revised, were not significantly different before and after the THP treatment. After the THP treatment, rCBF and rCMRO 2 decreased significantly in the striatum (about 15%) and all cerebral cortices (about 10%) on both sides contralateral and ipsilateral to the predominantly symptomatic limbs. We conclude that an anticholinergic THP decreases the rCBF and rCMRO 2 significantly in the cerebral cortices without cognitive impairment in early untreated patients with Parkinson's disease. (author)

  15. Increases in arterial blood oxygen during exercise in the lemon shark (Negaprion brevirostris)

    DEFF Research Database (Denmark)

    BUSHNELL, PG; LUTZ, PL; STEFFENSEN, JF

    1982-01-01

    Polyethylene cannulae were implanted in pre- and post-branchial blood vessels allowing nonstressful blood sampling over a variety of activity ranges in an active tropical elasmobranch, the lemon shark (Negaprion brevirostris). TheP 50 was found to be 11.8 Torr at 24°C and pH of 7.7. A Bohr shift...

  16. Measurement of regional cerebral blood flow by positron emission tomography

    International Nuclear Information System (INIS)

    Herscovitch, P.; Powers, W.J.

    1987-01-01

    The principal advantage of positron emission tomography over other methods for measuring cerebral blood flow stems from the accurate, quantitative three-dimensional measurements of regional brain radioactivity that are possible with this technique. As a result, accurate quantitative measurements of regional cerebral blood flow can be obtained for both superficial and deep cerebral structures. The value of PET for investigating central nervous system physiology and pathology extends far beyond this, however. Through the use of different radiotracers and appropriate mathematical models, PET can be applied to the measurement of a wide variety of physiologic variables. Measurements of rCBF tell only part of the story. Experience with PET and with a variety of other techniques has taught us that rCBF is at times a poor indicator of the metabolic, functional, and biochemical status of cerebral tissue. It is only by understanding the interaction of all of these factors that our understanding of neurologic disease can advance. It is in the investigation of these complex relationships that the real value of PET resides

  17. Noninvasive in vivo optical characterization of blood flow and oxygen consumption in the superficial plexus of skin

    Science.gov (United States)

    Liasi, Faezeh Talebi; Samatham, Ravikant; Jacques, Steven L.

    2017-11-01

    Assessing the metabolic activity of a tissue, whether normal, damaged, aged, or pathologic, is useful for diagnosis and evaluating the effects of drugs. This report describes a handheld optical fiber probe that contacts the skin, applies pressure to blanch the superficial vascular plexus of the skin, then releases the pressure to allow refill of the plexus. The optical probe uses white light spectroscopy to record the time dynamics of blanching and refilling. The magnitude and dynamics of changes in blood content and hemoglobin oxygen saturation yield an estimate of the oxygen consumption rate (OCR) in units of attomoles per cell per second. The average value of OCR on nine forearm sites on five subjects was 10±5 (amol/cell/s). This low-cost, portable, rapid, noninvasive optical probe can characterize the OCR of a skin site to assess the metabolic activity of the epidermis or a superficial lesion.

  18. Cutaneous and subcutaneous blood flow measurements in psoriasis

    International Nuclear Information System (INIS)

    Klemp, P.

    1987-01-01

    The experiments - published in 7 papers in The Journal of Investigative Dermatology 1983-86 - have demonstrated: 1. The accuracy of the local 133 Xe washout method is about 15% for estimation of the cutaneous blood flow (CBF), and about 10% for subcutaneous blood flow measurements (SBF). In measurements of absolute CBF values a graphic curve resolution of the washout curve should alwaus be performed. Otherwise the CBF might be considerably underestimated. 2. CdTe(Cl) mini-detectors can be attached directly to the skin, and might yield measurements of both CBF and SBF that can substitute for those made with conventional detectors. 3. The laser Doppler measurements could not be correlated to quantitative measurements of the CBF. 4. The tissue-to-blood partition coefficient for 133 Xe of lesional psoriatic skin (LS) is increased. 5. In untreated, LS of patients with active psoriasis the CBF is about a factor of 10 times higher than the CBF of normal individuals. In non-lesional skin (NLS) of patients with active psoriasis the CBF is about a factor of 2 higher than the CBF of normal individuals. However, the CBF did not differ in NLS of patients with minimal skin manifestations. The high CBF decreases gradualy during antipsoriatic treatment. 6. A paradoxical autoregulation of the CBF was observed in LS. 7. The high CBF is not due to a maximally dilated vascular bed. 8. The SBF in LS areas was a factor of higher than the SBF in normal individuals. 9. A normal, local regulation of the SBF was found. (author)

  19. Measurement of hydroxylated PCB metabolites for Slovakia maternal blood serums

    Energy Technology Data Exchange (ETDEWEB)

    Park, J.S.; Athanasiadou, M; Bergman, A. [Stockholm Univ., Stockholm (Sweden); Charles, J.; Zhao, G.; Hertz-Picciotto, I. [California Univ., Sacramento, CA (United States); Petrik, J.; Kocan, A; Trnovec, T. [Bratislava Inst. of Preventive and Clinical Medicine, Bratislava (Slovakia)

    2005-07-01

    Although it is known that polychlorinated biphenyls (PCBs) have adverse impacts on human health, it is not clear if human health impacts are caused by the PCBs or their related hydroxylated (OH) PCB metabolite compounds. This study measured OH-PCB metabolites in the maternal blood serum specimens from the Svidnik and Michalovce areas in eastern Slovakia where PCBs were intensively produced and inadequately disposed. The aim of the study was to characterize and quantify levels of specific OH-PCB metabolites in Slovakian maternal serums exposed to high environmental PCB levels. All specimens were analyzed for PCBs, and a subset of the samples was analyzed for OH-PCB metabolites. The Wallenburg blood extraction method was adopted to separate the OH-PCBs from the blood serums. Final eluates and calibration standards were spiked with PCB209 as an injection standard before gas chromatography (GC) analysis. OH-PCBs in the samples range from 75{+-}9 per cent to 101{+-}11 per cent. Median concentrations of OH-PCB metabolites of Michalovce samples were approximately twice as high as for the Svidnik samples. Concentrations of OH-PCBs of Michalovce blood samples were comparable to samples obtained from northern Canadian female Inuit and Faroe Island females, and were considered to be among the highest OH-PCB concentrations obtained in human blood. It was concluded that further research is needed to understand the placental transfer of OH-PCBs to the fetus, as well as epidemiological approaches to determine the relationship between the exposure of OH-PCB metabolites and child development. 12 refs., 2 figs.

  20. New Active Optical Technique Developed for Measuring Low-Earth-Orbit Atomic Oxygen Erosion of Polymers

    Science.gov (United States)

    Banks, Bruce A.; deGroh, Kim K.; Demko, Rikako

    2003-01-01

    Polymers such as polyimide Kapton (DuPont) and Teflon FEP (DuPont, fluorinated ethylene propylene) are commonly used spacecraft materials because of desirable properties such as flexibility, low density, and in the case of FEP, a low solar absorptance and high thermal emittance. Polymers on the exterior of spacecraft in the low-Earth-orbit (LEO) environment are exposed to energetic atomic oxygen. Atomic oxygen reaction with polymers causes erosion, which is a threat to spacecraft performance and durability. It is, therefore, important to understand the atomic oxygen erosion yield E (the volume loss per incident oxygen atom) of polymers being considered in spacecraft design. The most common technique for determining E is a passive technique based on mass-loss measurements of samples exposed to LEO atomic oxygen during a space flight experiment. There are certain disadvantages to this technique. First, because it is passive, data are not obtained until after the flight is completed. Also, obtaining the preflight and postflight mass measurements is complicated by the fact that many polymers absorb water and, therefore, the mass change due to water absorption can affect the E data. This is particularly true for experiments that receive low atomic oxygen exposures or for samples that have a very low E. An active atomic oxygen erosion technique based on optical measurements has been developed that has certain advantages over the mass-loss technique. This in situ technique can simultaneously provide the erosion yield data on orbit and the atomic oxygen exposure fluence, which is needed for erosion yield determination. In the optical technique, either sunlight or artificial light can be used to measure the erosion of semitransparent or opaque polymers as a result of atomic oxygen attack. The technique is simple and adaptable to a rather wide range of polymers, providing that they have a sufficiently high optical absorption coefficient. If one covers a photodiode with a

  1. First measurement of radon transfer. Water - skin - blood - air

    International Nuclear Information System (INIS)

    Philipsborn, H. von; Grunewald, W.A.

    2000-01-01

    While radon is disliked in uranium mines and homes, it is used medically in radon spas for the treatment of several ailments. The transfer of radon gas from water, through skin into blood and into expiratory air was studied completely for the first time for a person resting 20-30 min in radon water. For waterborne radon concentrations of 1500±100 Bq/L, 4±1 Bq/L were measured in the blood and 2.4±0.5 kBq/m 3 (Bq/L) in the expiratory air. The results can be understood according to the principles of physiology. The nature of the experiments excluded persons other than the authors. Hence the study has been radiometric (physical), not clinical (medical). (orig.)

  2. Multiple taxon multiple locality approach to providing oxygen isotope evidence for warm-blooded theropod dinosaurs

    Science.gov (United States)

    Fricke, Henry C.; Rogers, Raymond R.

    2000-09-01

    Oxygen isotope ratios of fossil remains of coexisting taxa from several different localities can be used to help investigate dinosaur thermoregulation. Focusing on the Late Cretaceous, oxygen isotope ratios of crocodile tooth enamel from four separate localities exhibit less of a decrease with latitude than do ratios of tooth enamel from coexisting theropod dinosaurs. A shallower latitudinal gradient for crocodiles is consistent with how oxygen isotope ratios should vary for heterothermic animals having body temperatures coupled with their environments (“cold blooded”), while a steeper gradient for theropods is consistent with how these ratios should vary for homeothermic animals having constant body temperatures independent of their environments (“warm blooded”). This inferred homoethermy in theropods is likely due to higher rates of metabolic heat production relative to crocodiles and is not an artifact of body size.

  3. Cerebral and Renal Oxygen Saturation Are Not Compromised in the Presence of Retrograde Blood Flow in either the Ascending or Descending Aorta in Term or Near-Term Infants with Left-Sided Obstructive Lesions.

    Science.gov (United States)

    van der Laan, Michelle E; Mebius, Mirthe J; Roofthooft, Marcus T R; Bos, Arend F; Berger, Rolf M F; Kooi, Elisabeth M W

    2017-01-01

    In infants with left-sided obstructive lesions (LSOL), the presence of retrograde blood flow in either the ascending or descending aorta may lead to diminished cerebral and renal blood flow, respectively. Our aim was to compare cerebral and renal tissue oxygen saturation (rSO2) between infants with LSOL with antegrade and retrograde blood flow in the ascending aorta and with and without diastolic backflow in the descending aorta. Based on 2 echocardiograms, the study group was categorized according to the direction of blood flow in the ascending and descending aorta. We measured cerebral and renal rSO2 using near-infrared spectroscopy and calculated fractional tissue oxygen extraction (FTOE). Nineteen infants with LSOL, admitted to the NICU between 0 and 28 days after birth, were included. Infants with antegrade blood flow (n = 12) and infants with retrograde blood flow in the ascending aorta (n = 7) had similar cerebral rSO2 and FTOE during both echocardiograms. Only during the first echocardiogram, infants with retrograde blood flow in the ascending aorta had lower renal FTOE (0.14 vs. 0.32, p = 0.04) and tended to have higher renal rSO2 (80 vs. 65%, p = 0.09). The presence of diastolic backflow in the descending aorta was not associated with cerebral or renal rSO2 and FTOE during the first (n = 8) as well as the second echocardiogram (n = 10). Retrograde blood flow in the ascending aorta was not associated with cerebral oxygenation, while diastolic backflow in the descending aorta was not associated with renal oxygenation in infants with LSOL. © 2017 S. Karger AG, Basel.

  4. A high precision method for quantitative measurements of reactive oxygen species in frozen biopsies.

    Directory of Open Access Journals (Sweden)

    Kirsti Berg

    Full Text Available OBJECTIVE: An electron paramagnetic resonance (EPR technique using the spin probe cyclic hydroxylamine 1-hydroxy-3-methoxycarbonyl-2,2,5,5-tetramethylpyrrolidine (CMH was introduced as a versatile method for high precision quantification of reactive oxygen species, including the superoxide radical in frozen biological samples such as cell suspensions, blood or biopsies. MATERIALS AND METHODS: Loss of measurement precision and accuracy due to variations in sample size and shape were minimized by assembling the sample in a well-defined volume. Measurement was carried out at low temperature (150 K using a nitrogen flow Dewar. The signal intensity was measured from the EPR 1st derivative amplitude, and related to a sample, 3-carboxy-proxyl (CP• with known spin concentration. RESULTS: The absolute spin concentration could be quantified with a precision and accuracy better than ±10 µM (k = 1. The spin concentration of samples stored at -80°C could be reproduced after 6 months of storage well within the same error estimate. CONCLUSION: The absolute spin concentration in wet biological samples such as biopsies, water solutions and cell cultures could be quantified with higher precision and accuracy than normally achievable using common techniques such as flat cells, tissue cells and various capillary tubes. In addition; biological samples could be collected and stored for future incubation with spin probe, and also further stored up to at least six months before EPR analysis, without loss of signal intensity. This opens for the possibility to store and transport incubated biological samples with known accuracy of the spin concentration over time.

  5. Hepatitis B Virus Blood Screening: Need for Reappraisal of Blood Safety Measures?

    Directory of Open Access Journals (Sweden)

    Daniel Candotti

    2018-02-01

    Full Text Available Over the past decades, the risk of HBV transfusion–transmission has been steadily reduced through the recruitment of volunteer donors, the selection of donors based on risk-behavior evaluation, the development of increasingly more sensitive hepatitis B antigen (HBsAg assays, the use of hepatitis B core antibody (anti-HBc screening in some low-endemic countries, and the recent implementation of HBV nucleic acid testing (NAT. Despite this accumulation of blood safety measures, the desirable zero risk goal has yet to be achieved. The residual risk of HBV transfusion–transmission appears associated with the preseroconversion window period and occult HBV infection characterized by the absence of detectable HBsAg and extremely low levels of HBV DNA. Infected donations tested false-negative with serology and/or NAT still persist and derived blood components were shown to transmit the virus, although rarely. Questions regarding the apparent redundancy of some safety measures prompted debates on how to reduce the cost of HBV blood screening. In particular, accumulating data strongly suggests that HBsAg testing may add little, if any HBV risk reduction value when HBV NAT and anti-HBc screening also apply. Absence or minimal acceptable infectious risk needs to be assessed before considering discontinuing HBsAg. Nevertheless, HBsAg remains essential in high-endemic settings where anti-HBc testing cannot be implemented without compromising blood availability. HBV screening strategy should be decided according to local epidemiology, estimate of the infectious risk, and resources.

  6. Preliminary results of oxygen isotope ratio measurement with a particle-gamma coincidence method

    Energy Technology Data Exchange (ETDEWEB)

    Borysiuk, Maciek, E-mail: maciek.borysiuk@pixe.lth.se; Kristiansson, Per; Ros, Linus; Abdel, Nassem S.; Elfman, Mikael; Nilsson, Charlotta; Pallon, Jan

    2015-04-01

    The possibility to study variations in the oxygen isotopic ratio with photon tagged nuclear reaction analysis (pNRA) is evaluated in the current work. The experiment described in the article was performed at Lund Ion Beam Analysis Facility (LIBAF) with a 2 MeV deuteron beam. Isotopic fractionation of light elements such as carbon, oxygen and nitrogen is the basis of many analytical tools in hydrology, geology, paleobiology and paleogeology. IBA methods provide one possible tool for measurement of isotopic content. During this experimental run we focused on measurement of the oxygen isotopic ratio. The measurement of stable isotopes of oxygen has a number of applications; the particular one driving the current investigation belongs to the field of astrogeology and specifically evaluation of fossil extraterrestrial material. There are three stable isotopes of oxygen: {sup 16}O, {sup 17}O and {sup 18}O. We procured samples highly enriched with all three isotopes. Isotopes {sup 16}O and {sup 18}O were easily detected in the enriched samples, but no significant signal from {sup 17}O was detected in the same samples. The measured yield was too low to detect {sup 18}O in a sample with natural abundances of oxygen isotopes, at least in the current experimental setup, but the spectral line from the reaction with {sup 16}O was clearly visible.

  7. Mucosal blood flow measurements using laser Doppler perfusion monitoring

    Institute of Scientific and Technical Information of China (English)

    Dag Arne Lihaug Hoff; Hans Gregersen; Jan Gunnar Hatlebakk

    2009-01-01

    Perfusion of individual tissues is a basic physiological process that is necessary to sustain oxygenation and nutrition at a cellular level. Ischemia, or the insufficiency of perfusion, is a common mechanism for tissue death or degeneration, and at a lower threshold, a mechanism for the generation of sensory signalling including pain. It is of considerable interest to study perfusion of peripheral abdominal tissues in a variety of circumstances. Microvascular disease of the abdominal organs has been implicated in the pathogenesis of a variety of disorders, including peptic ulcer disease, inflammatory bowel disease and chest pain. The basic principle of laser Doppler perfusion monitoring (LDPM) is to analyze changes in the spectrum of light reflected from tissues as a response to a beam of monochromatic laser light emitted. It reflects the total local microcirculatory blood perfusion, including perfusion in capillaries, arterioles, venules and shunts. During the last 20-25 years, numerous studies have been performed in different parts of the gastrointestinal (GI) tract using LDPM. In recent years we have developed a multi-modal catheter device which includes a laser Doppler probe, with the intent primarily to investigate patients suffering from functional chest pain of presumed oesophageal origin. Preliminary studies show the feasibility of incorporating LDPM into such catheters for performing physiological studies in the GI tract. LDPM has emerged as a research and clinical tool in preference to other methods; but, it is important to be aware of its limitations and account for them when reporting results.

  8. Effects of Cortical Spreading Depression on Synaptic Activity, Blood Flow and Oxygen Consumption in Rat Cerebral Cortex

    DEFF Research Database (Denmark)

    Hansen, Henning Piilgaard

    2010-01-01

    As the title of this thesis indicates I have during my PhD studied the effects of cortical spreading depression (CSD) on synaptic activity, blood flow and oxygen consumption in rat cerebral cortex. This was performed in vivo using an open cranial window approach in anesthetized rats. I applied...... parameters of the whisker/infraorbital nerve etwork (IO) targeting the same cortical area. We tested the hypothesis that the relation between increases in CBF and CMRO2 evoked by stimulation and synaptic activity differed for the two activated networks and that activation of two distinct networks activate...

  9. The whole blood oxygen binding properties of a large but presumably sluggish polar elasmobranch, the Greenland shark Somniosus microcephalus

    DEFF Research Database (Denmark)

    Steffensen, John Fleng

    2012-01-01

    ) is the most notable example. These extremely large and long-lived sharks are thought to be sluggish but their active hunting lifestyle has recently been questioned by the finding of mobile prey species in their stomach (i.e. squid, fish and seal). The whole blood oxygen binding property of S. microcephalus......Australian and New Zealand Society for Comparative Physiology and Biochemistry. Auckland, N.Z., December 2012. Herbert, N.A.1, Skov, p.V.l, Tirsgaard, B.z and Steffensen, J.F. Z Only a few species of elasmobranch live in cold polar waters and the Greenland shark (Somniosus microcephalus...

  10. Low Cerebral Oxygen Consumption and Blood Flow in Patients With Cirrhosis and an Acute Episode of Hepatic Encephalopathy

    DEFF Research Database (Denmark)

    Iversen, Peter; Bak, Lasse Kristoffer; Waagepetersen, Helle Sønderby

    2009-01-01

    (15)O-water PET in 6 patients with liver cirrhosis and an acute episode of overt HE, 6 cirrhotic patients without HE, and 7 healthy subjects. RESULTS: Neither whole-brain CMRO(2) nor CBF differed significantly between cirrhotic patients without HE and healthy subjects, but were both significantly...... that the reductions in CMRO(2) and CBF in patients with HE were essentially generalized throughout the brain. CONCLUSIONS: The observations imply that reduced cerebral oxygen consumption and blood flow in cirrhotic patients with an acute episode of overt HE are associated with HE and not cirrhosis as such...

  11. Megalophallus as a sequela of priapism in sickle cell anemia: use of blood oxygen level-dependent magnetic resonance imaging.

    Science.gov (United States)

    Kassim, A A; Umans, H; Nagel, R L; Fabry, M E

    2000-09-01

    Priapism is a common complication of sickle cell anemia. We report a little known sequela of priapism: painless megalophallus, with significant penile enlargement. The patient had had an intense episode of priapism 9 years previously and his penis remained enlarged. Blood oxygen level-dependent magnetic resonance imaging revealed enlarged, hypoxic corpora cavernosa. Megalophallus probably resulted from permanent loss of elasticity of the tunica albuginea due to severe engorgement during the episode of priapism. This sequela needs to be recognized by physicians because no intervention is necessary and sexual function seems to remain intact.

  12. Red blood cell-deformability measurement: review of techniques.

    Science.gov (United States)

    Musielak, M

    2009-01-01

    Cell-deformability characterization involves general measurement of highly complex relationships between cell biology and physical forces to which the cell is subjected. The review takes account of the modern technical solutions simulating the action of the force applied to the red blood cell in macro- and microcirculation. Diffraction ektacytometers and rheoscopes measure the mean deformability value for the total red blood cell population investigated and the deformation distribution index of individual cells, respectively. Deformation assays of a whole single cell are possible by means of optical tweezers. The single cell-measuring setups for micropipette aspiration and atomic force microscopy allow conducting a selective investigation of deformation parameters (e.g., cytoplasm viscosity, viscoelastic membrane properties). The distinction between instrument sensitivity to various RBC-rheological features as well as the influence of temperature on measurement are discussed. The reports quoted confront fascinating possibilities of the techniques with their medical applications since the RBC-deformability has the key position in the etiology of a wide range of conditions.

  13. Proton RBS measurement of the oxygen in heavy-metal oxides

    International Nuclear Information System (INIS)

    Xie, T.; Ryan, S.R.; Fischbeck, H.J.

    1989-01-01

    Although the stoichoimetry of high-T c superconductors is often measured using alpha-particle RBS, the small Rutherford cross section for oxygen relative to the high-Z components makes a determination of the oxygen content difficult. Above 1 MeV, the cross section for proton backscattering from oxygen becomes significantly greater than the Rutherford cross section. Studies of proton backscattering in CuO between 0.6 and 2.0 MeV show that it is possible to measure the oxygen content of high-Z metal oxides. RBS simulations using the Bragg-rule stopping power consistently underestimate the low-energy yield. Scaling the stopping power by a linear function of energy to reduce loss at low energy improves the simulation in CuO, Cu and Au. This general result suggests that the standard RBS simulation procedure may omit some relevant physics. (orig.)

  14. Study of cerebral blood flow and oxygen utilization in the edematous area and ipsilateral hemispheric gray matter using positron emission tomography in brain tumors

    International Nuclear Information System (INIS)

    Ikeda, Yusuke

    1990-01-01

    We measured the cerebral blood flow and oxygen utilization of the peritumoral white matter and ipsilateral hemispheric gray matter in 50 patients with brain tumors using Positron Emission Tomography (PET). The intraaxial tumors consisted of 34 cases (25 of gliomas, 6 of metastatic tumors, and 3 others), white the extraaxial tumors (all of meningiomas) were 16 cases. The cases were divided into 2 groups on the basis of the Xray CT scan findings. The cases of Edema (+) group showed moderate or large peritumoral edema in the white matter on the Xray CT scan, while Edema (-) group showed no or small edema. The method of PET study was the 15 O steady state inhalation technique by Frackoviak's method. ROIs (region of interest) were set on the peritumoral white matter and the ipsilateral hemispheric gray matter, and the mean CBF, OEF and CMRO2 values of the white and gray matter were calculated. In the Edema (+) group, the mean values of blood flow and oxygen utilization were low in the peritumoral white matter, and there were no obvious differences of values between intra and extraaxial tumors. But, the values in the ipsilateral hemispheric gray matter of intraaxial tumors were lower than those of extraaxial tumor. In the Edema (-) group, the mean values were almost normal in the white and gray matter, and there were no differences between intra and extraaxial tumors. The consideration about significance of the above stated results was discussed added with literature. (author)

  15. Automatic labeling method for injectable 15O-oxygen using hemoglobin-containing liposome vesicles and its application for measurement of brain oxygen consumption by PET

    International Nuclear Information System (INIS)

    Tiwari, Vijay Narayan; Kiyono, Yasushi; Kobayashi, Masato; Mori, Tetsuya; Kudo, Takashi; Okazawa, Hidehiko; Fujibayashi, Yasuhisa

    2010-01-01

    Introduction: The aim of this study was to develop an injectable 15 O-O 2 system using hemoglobin-containing vesicles (HbV), a type of artificial red blood cell, and to investigate the feasibility of 15 O 2 -labeled HbV ( 15 O 2 -HbV) to measure cerebral metabolic rate of oxygen (CMRO 2 ) in rats. Methods: The direct bubbling method was combined with vortexing to enhance labeling efficiency of HbV with 15 O-O 2 gas. L-Cysteine was added as a reductant to protect hemoglobin molecules in HbV from oxidation at different concentrations, and labeling efficiencies were also compared. Measurement of cerebral blood flow (CBF) and CMRO 2 in five normal rats was performed using a small animal PET scanner after the injection of H 2 15 O and 15 O 2 -HbV to evaluate the precision of hemodynamic parameters quantitatively. Results: The labeling efficiency of HbV was significantly increased when vortexing and bubbling were combined compared with the simple bubbling method (P 15 O-O 2 combined with vortexing and the addition of 2.8 mM L-cysteine in HbV solution. The mean radioactivity of 214.4±7.8 MBq/mL HbV was obtained using this method. PET scans using 15 O 2 -HbV and H 2 15 O yielded a mean CMRO 2 value of 6.8±1.4 (mL/min per 100 g) in rats with normal CBF of 51.4±7.9 (mL/min per 100 g). Conclusion: Addition of L-cysteine to HbV and simple direct bubbling of 15 O-O 2 gas combined with vortexing was the most efficient method for preparation of 15 O 2 -HbV. The present injectable system using 15 O 2 -HbV was successfully utilized to measure CMRO 2 in rats, indicating that this new method could be useful for animal models to measure oxygen metabolism in the brain.

  16. Automatic labeling method for injectable {sup 15}O-oxygen using hemoglobin-containing liposome vesicles and its application for measurement of brain oxygen consumption by PET

    Energy Technology Data Exchange (ETDEWEB)

    Tiwari, Vijay Narayan [Biomedical Imaging Research Center, University of Fukui, Fukui (Japan)], E-mail: tiwaridr@u-fukui.ac.jp; Kiyono, Yasushi; Kobayashi, Masato; Mori, Tetsuya; Kudo, Takashi [Biomedical Imaging Research Center, University of Fukui, Fukui (Japan); Okazawa, Hidehiko [Biomedical Imaging Research Center, University of Fukui, Fukui (Japan); Research and Education Program for Life Science, University of Fukui, Fukui (Japan); Fujibayashi, Yasuhisa [Biomedical Imaging Research Center, University of Fukui, Fukui (Japan); Research and Education Program for Life Science, University of Fukui, Fukui (Japan)], E-mail: yfuji@u-fukui.ac.jp

    2010-01-15

    Introduction: The aim of this study was to develop an injectable {sup 15}O-O{sub 2} system using hemoglobin-containing vesicles (HbV), a type of artificial red blood cell, and to investigate the feasibility of {sup 15}O{sub 2}-labeled HbV ({sup 15}O{sub 2}-HbV) to measure cerebral metabolic rate of oxygen (CMRO{sub 2}) in rats. Methods: The direct bubbling method was combined with vortexing to enhance labeling efficiency of HbV with {sup 15}O-O{sub 2} gas. L-Cysteine was added as a reductant to protect hemoglobin molecules in HbV from oxidation at different concentrations, and labeling efficiencies were also compared. Measurement of cerebral blood flow (CBF) and CMRO{sub 2} in five normal rats was performed using a small animal PET scanner after the injection of H{sub 2}{sup 15}O and {sup 15}O{sub 2}-HbV to evaluate the precision of hemodynamic parameters quantitatively. Results: The labeling efficiency of HbV was significantly increased when vortexing and bubbling were combined compared with the simple bubbling method (P<.05). The most efficient method for labeling was bubbling of {sup 15}O-O{sub 2} combined with vortexing and the addition of 2.8 mM L-cysteine in HbV solution. The mean radioactivity of 214.4{+-}7.8 MBq/mL HbV was obtained using this method. PET scans using {sup 15}O{sub 2}-HbV and H{sub 2}{sup 15}O yielded a mean CMRO{sub 2} value of 6.8{+-}1.4 (mL/min per 100 g) in rats with normal CBF of 51.4{+-}7.9 (mL/min per 100 g). Conclusion: Addition of L-cysteine to HbV and simple direct bubbling of {sup 15}O-O{sub 2} gas combined with vortexing was the most efficient method for preparation of {sup 15}O{sub 2}-HbV. The present injectable system using {sup 15}O{sub 2}-HbV was successfully utilized to measure CMRO{sub 2} in rats, indicating that this new method could be useful for animal models to measure oxygen metabolism in the brain.

  17. Exogenous and endogenous angiotensin-II decrease renal cortical oxygen tension in conscious rats by limiting renal blood flow

    NARCIS (Netherlands)

    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; Koeners, Maarten P.

    2016-01-01

    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

  18. Combination of hyperbaric oxygenation, blood ultraviolet irradiation and hemisorption in treatment of patients with postoperational peritonitis

    International Nuclear Information System (INIS)

    Lisak, B.I.; Ivanov, M.A.

    1988-01-01

    Results of treatment of patients with postoperational peritonitis are taken as examples to carry out a comparative evaluation of modern methods of correction of changes of homeostasis and detoxication-hemisorption, ultraviolet irradiation of autoblood, hyperbaric oxygenation, as well as of traditional approach to removal of intra-abdominal sepsis in isolated version. 69 refs.; 3 tabs

  19. Image-Based Modeling of Blood Flow and Oxygen Transfer in Feto-Placental Capillaries

    Czech Academy of Sciences Publication Activity Database

    Pearce, P.; Brownbill, P.; Janáček, Jiří; Jirkovská, M.; Kubínová, Lucie; Chernyavsky, I. L.; Jensen, O. E.

    2016-01-01

    Roč. 11, č. 10 (2016), č. článku e0165369. E-ISSN 1932-6203 Institutional support: RVO:67985823 Keywords : placenta * capillaries * oxygen transfer * confocal microscopy Subject RIV: EA - Cell Biology Impact factor: 2.806, year: 2016

  20. Simultaneous compared with sequential blood pressure measurement results in smaller inter-arm blood pressure differences.

    Science.gov (United States)

    van der Hoeven, Niels V; Lodestijn, Sophie; Nanninga, Stephanie; van Montfrans, Gert A; van den Born, Bert-Jan H

    2013-11-01

    There are currently few recommendations on how to assess inter-arm blood pressure (BP) differences. The authors compared simultaneous with sequential measurement on mean BP, inter-arm BP differences, and within-visit reproducibility in 240 patients stratified according to age (simultaneous and three sequential BP measurements were taken in each patient. Starting measurement type and starting arm for sequential measurements were randomized. Mean BP and inter-arm BP differences of the first pair and reproducibility of inter-arm BP differences of the first and second pair were compared between both methods. Mean systolic BP was 1.3±7.5 mm Hg lower during sequential compared with simultaneous measurement (Psequential measurement was on average higher than the second, suggesting an order effect. Absolute systolic inter-arm BP differences were smaller on simultaneous (6.2±6.7/3.3±3.5 mm Hg) compared with sequential BP measurement (7.8±7.3/4.6±5.6 mm Hg, PSimultaneous measurement of BP at both arms reduces order effects and results in smaller inter-arm BP differences, thereby potentially reducing unnecessary referral and diagnostic procedures. ©2013 Wiley Periodicals, Inc.

  1. Rapid measurement of blood leakage during regional chemotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Alexander, C. (Universitaet des Saarlandes, Homburg/Saar (Germany). Abt. fuer Nuklearmedizin); Omlor, G.; Gross, G.; Feifel, G. (Universitaet des Saarlandes, Homburg/Saar (Germany). Abt. fuer Allgemeine Chirurgie); Berberich, R. (Staedtische Klinik Wuppertal (Germany). Abt. fuer Nuklearmedizin)

    1993-03-01

    A method using technetium-99m in vivo red blood cell (RBC) labelling is reported that provides results within 3 min. Blood samples drawn from the systemic and the extracorporeal circulation were measured for [sup 99m]Tc activity using a mobile well counter, and the leakage values calculated. The mean result was 7.6%[+-]6.5%/15 min (n=209). The corresponding flow rate was 100.2[+-]85.7 ml/15 min. The values for isolation perfusion of the upper and the lower extremities are compared. The leakage results using [sup 99m]Tc RBC labelling were correlated with other blood pool markers. Iodine-125 human serum albumin and indium-113 m transferrin were administered in subgroups of 4 and 19 patients simultaneously. Using linear regression, the coefficient of correlation was 0.72 for [sup 99m]Tc/[sup 113m]In and 0.58 for [sup 99m]Tc/[sup 125]I. Comparison with the alternatives suggests that the method can be considered one of the most practicable and reliable methods available. (orig.).

  2. Respiratory adaptations in carp blood. Influences of hypoxia, red cell organic phosphates, divalent cations and CO2 on hemoglobin-oxygen affinity

    DEFF Research Database (Denmark)

    Weber, Roy E.; Lykkeboe, G.

    1978-01-01

    This study concerns the adaptation of oxygen transporting function of carp blood to environment hypoxia, tracing the roles played by erythrocytic cofactors, inorganic cations, carbon dioxide and hemoglobin multiplicity. Carp acclimated to hypoxia ( 30 mmHg) display striking increases in blood oxy...

  3. Out-of-office blood pressure: from measurement to control

    Directory of Open Access Journals (Sweden)

    Baguet JP

    2012-05-01

    Full Text Available Jean-Philippe Baguet1,21Department of Cardiology, University Hospital, 2Bioclinic Radiopharmaceutics Laboratory, INSERM U1039, Joseph Fourier University, Grenoble, FranceAbstract: Hypertension is an important risk factor for the development of cardiovascular disease, and is a major cause of morbidity and mortality worldwide. Traditionally, hypertension diagnosis and treatment and clinical evaluations of antihypertensive efficacy have been based on office blood pressure (BP measurements; however, there is increasing evidence that office measures may provide inadequate or misleading estimates of a patient’s true BP status and level of cardiovascular risk. The introduction, and endorsement by treatment guidelines, of 24-hour ambulatory BP monitoring and self (or home BP monitoring has facilitated more reliable and reproducible estimations of true BP, including the identification of white-coat and masked hypertension, and evaluation of BP variability. In addition, ambulatory BP monitoring enables accurate assessment of treatment effectiveness over 24 hours and both ambulatory and self BP monitoring may lead to better tailoring of therapy according to BP profile and concomitant disease. This review describes the clinical benefits and limitations of out-of-office assessments and their applications for effective management of hypertension and attainment of BP control.Keywords: ambulatory, ABPM, SBPM, blood pressure measurement, hypertension

  4. Rotating permanent magnet excitation for blood flow measurement.

    Science.gov (United States)

    Nair, Sarath S; Vinodkumar, V; Sreedevi, V; Nagesh, D S

    2015-11-01

    A compact, portable and improved blood flow measurement system for an extracorporeal circuit having a rotating permanent magnetic excitation scheme is described in this paper. The system consists of a set of permanent magnets rotating near blood or any conductive fluid to create high-intensity alternating magnetic field in it and inducing a sinusoidal varying voltage across the column of fluid. The induced voltage signal is acquired, conditioned and processed to determine its flow rate. Performance analysis shows that a sensitivity of more than 250 mV/lpm can be obtained, which is more than five times higher than conventional flow measurement systems. Choice of rotating permanent magnet instead of an electromagnetic core generates alternate magnetic field of smooth sinusoidal nature which in turn reduces switching and interference noises. These results in reduction in complex electronic circuitry required for processing the signal to a great extent and enable the flow measuring device to be much less costlier, portable and light weight. The signal remains steady even with changes in environmental conditions and has an accuracy of greater than 95%. This paper also describes the construction details of the prototype, the factors affecting sensitivity and detailed performance analysis at various operating conditions.

  5. Cerebral blood flow measurement in cerebrovascular occlusive diseases

    International Nuclear Information System (INIS)

    Yanagihara, T.; Wahner, H.W.

    1984-01-01

    In order to evaluate cerebral blood flow (CBF) patterns among individual patients with increased statistical confidence, CBF measurements were carried out using the 133Xe-inhalation method and external head detectors. F1 values representing gray matter flow from 3 to 6 head detectors were averaged to form 16 different regions for each cerebral hemisphere. Normative values were obtained from 46 healthy volunteers, and data from individual regions were analyzed for absolute blood flow rates (ml/100g/min), for concordance between right and left hemispheres and as percent of mean hemispheric flow. CBF measurements were then carried out among 37 patients with cerebrovascular occlusive diseases, and results were compared with normative values. A high incidence of abnormal flows were detected among symptomatic patients with intracranial arterial stenosis or occlusion and those with extracranial internal carotid artery occlusion. By using the above method for data analysis, it was possible to delineate hypoperfused areas among these patients. Even though the 133Xe-inhalation method has inherent limitations, this is a practical and safe method for measurement of CBF which can provide reliable information useful for management of patients with cerebrovascular occlusive diseases, particularly when the results are presented with statistical confidence

  6. Measurements of electron attachment by oxygen molecule in proportional counter

    Energy Technology Data Exchange (ETDEWEB)

    Tosaki, M., E-mail: tosaki.mitsuo.3v@kyoto-u.ac.jp [Radioisotope Research Center, Kyoto University, Kyoto 606-8501 (Japan); Kawano, T. [National Institute for Fusion Science, 322-6 Oroshi, Toki 509-5292 (Japan); Isozumi, Y. [Radioisotope Research Center, Kyoto University, Kyoto 606-8501 (Japan)

    2013-11-15

    We present pulse height measurements for 5-keV Auger electrons from a radioactive {sup 55}Fe source mounted at the inner cathode surface of cylindrical proportional counter, which is operated with CH{sub 4} admixed dry air or N{sub 2}. A clear shift of the pulse height has been observed by varying the amount of the admixtures; the number of electrons, created in the primary ionization by Auger electrons, is decreased by the electron attachment of the admixtures during their drift from the place near the source to the anode wire. The large gas amplification (typically 10{sup 4}) in the secondary ionization of proportional counter makes it possible to investigate a small change in the number of primary electrons. The electron attenuation cross-section of O{sub 2} has been evaluated by analyzing the shifts of the pulse height caused by the electron attachment to dry air and N{sub 2}.

  7. Standardization for oxygen isotope ratio measurement - still an unsolved problem.

    Science.gov (United States)

    Kornexl; Werner; Gehre

    1999-07-01

    Numerous organic and inorganic laboratory standards were gathered from nine European and North American laboratories and were analyzed for their delta(18)O values with a new on-line high temperature pyrolysis system that was calibrated using Vienna standard mean ocean water (VSMOW) and standard light Antartic precipitation (SLAP) internationally distributed reference water samples. Especially for organic materials, discrepancies between reported and measured values were high, ranging up to 2 per thousand. The reasons for these discrepancies are discussed and the need for an exact and reliable calibration of existing reference materials, as well as for the establishment of additional organic and inorganic reference materials is stressed. Copyright 1999 John Wiley & Sons, Ltd.

  8. Feed-derived volatile basic nitrogen increases reactive oxygen species production of blood leukocytes in lactating dairy cows.

    Science.gov (United States)

    Tsunoda, Ei; Gross, Josef J; Kawashima, Chiho; Bruckmaier, Rupert M; Kida, Katsuya; Miyamoto, Akio

    2017-01-01

    The present study investigated over 9 months the changes of fermentative quality of total mixed rations (TMR) containing grass silage (GS) as a major component, associated with changes in the volatile basic nitrogen (VBN) levels in an experimental dairy farm. Effects of VBN levels in TMR on metabolic parameters, reactive oxygen species (ROS) production by blood polymorphonuclear leukocytes (PMNs) and conception rates for dairy cows were analyzed. According to VBN levels in TMR during survey periods, three distinct phases were identified; phase A with low VBN; phase B with high VBN; and phase C with mid-VBN. Metabolic parameters in blood were all within normal range. However, during phases B and C, nitrogen metabolic indices such as blood urea nitrogen and milk urea nitrogen showed higher levels compared to those in phase A, and a simultaneous increase in ROS production by blood PMNs and the load on hepatic function in metabolic parameters was observed in the cows with a lower conception rate. This suggests that feeding TMR with elevated VBN levels due to poor fermented GS results in stimulation of ROS production by PMNs by ammonia, and negatively affects metabolism and reproductive performance in lactating dairy cow. © 2016 Japanese Society of Animal Science.

  9. Common Genetic Polymorphisms Influence Blood Biomarker Measurements in COPD

    Science.gov (United States)

    Drummond, M. Bradley; Hawkins, Gregory A.; Yang, Jenny; Chen, Ting-huei; Quibrera, Pedro Miguel; Anderson, Wayne; Barr, R. Graham; Bleecker, Eugene R.; Beaty, Terri; Casaburi, Richard; Castaldi, Peter; Cho, Michael H.; Comellas, Alejandro; Crapo, James D.; Criner, Gerard; Demeo, Dawn; Christenson, Stephanie A.; Couper, David J.; Doerschuk, Claire M.; Freeman, Christine M.; Gouskova, Natalia A.; Han, MeiLan K.; Hanania, Nicola A.; Hansel, Nadia N.; Hersh, Craig P.; Hoffman, Eric A.; Kaner, Robert J.; Kanner, Richard E.; Kleerup, Eric C.; Lutz, Sharon; Martinez, Fernando J.; Meyers, Deborah A.; Peters, Stephen P.; Regan, Elizabeth A.; Rennard, Stephen I.; Scholand, Mary Beth; Silverman, Edwin K.; Woodruff, Prescott G.; O’Neal, Wanda K.; Bowler, Russell P.

    2016-01-01

    Implementing precision medicine for complex diseases such as chronic obstructive lung disease (COPD) will require extensive use of biomarkers and an in-depth understanding of how genetic, epigenetic, and environmental variations contribute to phenotypic diversity and disease progression. A meta-analysis from two large cohorts of current and former smokers with and without COPD [SPIROMICS (N = 750); COPDGene (N = 590)] was used to identify single nucleotide polymorphisms (SNPs) associated with measurement of 88 blood proteins (protein quantitative trait loci; pQTLs). PQTLs consistently replicated between the two cohorts. Features of pQTLs were compared to previously reported expression QTLs (eQTLs). Inference of causal relations of pQTL genotypes, biomarker measurements, and four clinical COPD phenotypes (airflow obstruction, emphysema, exacerbation history, and chronic bronchitis) were explored using conditional independence tests. We identified 527 highly significant (p 10% of measured variation in 13 protein biomarkers, with a single SNP (rs7041; p = 10−392) explaining 71%-75% of the measured variation in vitamin D binding protein (gene = GC). Some of these pQTLs [e.g., pQTLs for VDBP, sRAGE (gene = AGER), surfactant protein D (gene = SFTPD), and TNFRSF10C] have been previously associated with COPD phenotypes. Most pQTLs were local (cis), but distant (trans) pQTL SNPs in the ABO blood group locus were the top pQTL SNPs for five proteins. The inclusion of pQTL SNPs improved the clinical predictive value for the established association of sRAGE and emphysema, and the explanation of variance (R2) for emphysema improved from 0.3 to 0.4 when the pQTL SNP was included in the model along with clinical covariates. Causal modeling provided insight into specific pQTL-disease relationships for airflow obstruction and emphysema. In conclusion, given the frequency of highly significant local pQTLs, the large amount of variance potentially explained by pQTL, and the

  10. Common Genetic Polymorphisms Influence Blood Biomarker Measurements in COPD.

    Directory of Open Access Journals (Sweden)

    Wei Sun

    2016-08-01

    Full Text Available Implementing precision medicine for complex diseases such as chronic obstructive lung disease (COPD will require extensive use of biomarkers and an in-depth understanding of how genetic, epigenetic, and environmental variations contribute to phenotypic diversity and disease progression. A meta-analysis from two large cohorts of current and former smokers with and without COPD [SPIROMICS (N = 750; COPDGene (N = 590] was used to identify single nucleotide polymorphisms (SNPs associated with measurement of 88 blood proteins (protein quantitative trait loci; pQTLs. PQTLs consistently replicated between the two cohorts. Features of pQTLs were compared to previously reported expression QTLs (eQTLs. Inference of causal relations of pQTL genotypes, biomarker measurements, and four clinical COPD phenotypes (airflow obstruction, emphysema, exacerbation history, and chronic bronchitis were explored using conditional independence tests. We identified 527 highly significant (p 10% of measured variation in 13 protein biomarkers, with a single SNP (rs7041; p = 10-392 explaining 71%-75% of the measured variation in vitamin D binding protein (gene = GC. Some of these pQTLs [e.g., pQTLs for VDBP, sRAGE (gene = AGER, surfactant protein D (gene = SFTPD, and TNFRSF10C] have been previously associated with COPD phenotypes. Most pQTLs were local (cis, but distant (trans pQTL SNPs in the ABO blood group locus were the top pQTL SNPs for five proteins. The inclusion of pQTL SNPs improved the clinical predictive value for the established association of sRAGE and emphysema, and the explanation of variance (R2 for emphysema improved from 0.3 to 0.4 when the pQTL SNP was included in the model along with clinical covariates. Causal modeling provided insight into specific pQTL-disease relationships for airflow obstruction and emphysema. In conclusion, given the frequency of highly significant local pQTLs, the large amount of variance potentially explained by pQTL, and the

  11. A general model to calculate the spin-lattice (T1) relaxation time of blood, accounting for haematocrit, oxygen saturation and magnetic field strength.

    Science.gov (United States)

    Hales, Patrick W; Kirkham, Fenella J; Clark, Christopher A

    2016-02-01

    Many MRI techniques require prior knowledge of the T1-relaxation time of blood (T1bl). An assumed/fixed value is often used; however, T1bl is sensitive to magnetic field (B0), haematocrit (Hct), and oxygen saturation (Y). We aimed to combine data from previous in vitro measurements into a mathematical model, to estimate T1bl as a function of B0, Hct, and Y. The model was shown to predict T1bl from in vivo studies with a good accuracy (± 87 ms). This model allows for improved estimation of T1bl between 1.5-7.0 T while accounting for variations in Hct and Y, leading to improved accuracy of MRI-derived perfusion measurements. © The Author(s) 2015.

  12. Measurement of regional pulmonary blood volume in patients with increased pulmonary blood flow or pulmonary arterial hypertension

    International Nuclear Information System (INIS)

    Wollmer, P.; Rozcovek, A.; Rhodes, C.G.; Allan, R.M.; Maseri, A.

    1984-01-01

    The effects of chronic increase in pulmonary blood flow and chronic pulmonary hypertension on regional pulmonary blood volume was measured in two groups of patients. One group of patients had intracardiac, left-to-right shunts without appreciable pulmonary hypertension, and the other consisted of patients with Eisenmenger's syndrome or primary pulmonary hypertension, i.e. patients with normal or reduced blood flow and severe pulmonary hypertension. A technique based on positron tomography was used to measure lung density (by transmission scanning) and regional pulmonary blood volume (after inhalation of /sup 11/CO). The distribution of pulmonary blood volume was more uniform in patients with chronic increase in pulmonary blood flow than in normal subjects. There were also indications of an absolute increase in intrapulmonary blood volume by about 15%. In patients with chronic pulmonary arterial hypertension, the distribution of pulmonary blood volume was also abnormally uniform. There was, however, no indication that overall intrapulmonary blood volume was substantially different from normal subjects. The abnormally uniform distribution of pulmonary blood volume can be explained by recruitment and/or dilatation of vascular beds. Intrapulmonary blood volume appears to be increased in patients with intracardiac, left-to-right shunts. With the development of pulmonary hypertension, intrapulmonary blood volume falls, which may be explained by reactive changes in the vasculature and/or obliteration of capillaries

  13. Relationship between level of forage intake, blood flow and oxygen consumption by splanchnic tissues of sheep fed a tropical grass forage.

    Science.gov (United States)

    Hentz, F; Kozloski, G V; Zeni, D; Brun, M V; Stefanello, S

    2017-02-01

    Four Polwarth castrated male sheep (42 ± 4.4 kg live weight (LW) surgically implanted with chronic indwelling catheters into the mesenteric, portal and hepatic veins, housed in metabolism cages and offered Cynodon sp. hay at rates (g of dry matter (DM)/kg LW) of 7, 14, 21 or ad libitum, were used in a 4 × 4 Latin square experiment to evaluate the effect of the level of forage intake on blood flow and oxygen consumption by the portal-drained viscera (PDV), liver and total splanchnic tissues (ST). The portal blood flow and the oxygen consumption by PDV linearly increased at increased organic matter (OM) intake. No effect of level of OM intake was obtained for the hepatic artery blood flow and oxygen consumption by liver. As a consequence, the level of OM intake only tended to directly affect hepatic blood flow and oxygen consumption by total ST. Oxygen consumption was linearly and positively related to blood flow across PDV, liver and total ST. The heat production by PDV and total ST, as proportion of metabolizable energy (ME) intake, decreased curvilinearly at increased ME intake. In conclusion, the oxygen consumption by PDV, but not by liver, was directly related to the level of forage intake by sheep. Moreover, when ingested at levels below maintenance, most of ME was spent as heat produced by ST. Journal of Animal Physiology and Animal Nutrition © 2016 Blackwell Verlag GmbH.

  14. Effects of spinal immobilization at a 20° angle on cerebral oxygen saturations measured by INVOS™.

    Science.gov (United States)

    Aksel, Gökhan

    2018-01-01

    In this study, we aimed to investigate whether performing the immobilization at 20° instead of 0° changes cerebral oxygenation. 33 volunteers were put in a hard cervical collar and backboard at 0° and immobilized for 30min. The cerebral oxygen saturations of the volunteers were measured at 1, 5, and 30min after the start of the procedure (Group 1). The volunteers were asked to return the day after the Group 1 procedure but at the same time. Serial cerebral oxygen saturations were obtained at the same time intervals as in Group 1, but for Group 2, the backboard was set to 20°. When the cerebral oxygen saturations of the two groups were compared, there was a slight decrease when the backboard position was changed from 0° to 20°, but it was not statistically significant (P=0.220 and P=0.768, respectively). The results revealed that immobilizing the patients with a spinal backboard at 20° instead of 0° did not alter the cerebral oxygen saturations. Our study results revealed that spinal immobilization at 20°, which was a new suggestion for spinal immobilization following a report that this position reduced the decrease in pulmonary function secondary to spinal immobilization, did not alter the cerebral oxygenation, so this suggestion is safe at least from the standpoint of cerebral oxygenation. Copyright © 2017 Elsevier Inc. All rights reserved.

  15. Cerebral blood flow and oxygen metabolism in senile dementia of Alzheimer's type and vascular dementia with deep white matter changes

    International Nuclear Information System (INIS)

    Tohgi, H.; Yonezawa, H.; Takahashi, S.; Sato, N.; Kato, E.; Kudo, M.; Hatano, K.; Sasaki, T.

    1998-01-01

    Regional cerebral blood flow (rCBF), cerebral metabolic rate of oxygen (rCMRO 2 ), oxygen extraction fraction (rOEF), and cerebral blood volume (rCBV) were investigated using positron emission tomography (PET) in 16 patients with senile dementia of Alzheimer's type (SDAT), and compared with those of 6 nondemented and 3 demented patients with deep white matter high signal (DWMH) on T2-weighted MRI and 6 controls. rCBF, rCMRO 2 and rCBV were determined using C 15 O 2 , 15 O 2 and C 15 O, respectively. rCBF and CMRO 2 were significantly decreased in the frontal, parietal and temporal cortex (P 2 was significantly reduced in only the frontal and temporal cortex of demented patients (P < 0.05). rOEF was significantly increased in the parietal cortex of patients with SDAT and in the white matter of patients with SDAT or DWMH (P < 0.05), and the increase in the frontal white matter significantly paralleled the progression of dementia in patients with SDAT (P < 0.05). rCBV was significantly decreased in the parietal and temporal cortex of patients with SDAT (P < 0.05), but not in any areas of those with DWMH. (orig.)

  16. Replacing the Transfusion of 1–2 Units of Blood with Plasma Expanders that Increase Oxygen Delivery Capacity: Evidence from Experimental Studies

    Directory of Open Access Journals (Sweden)

    Amy G. Tsai

    2014-10-01

    Full Text Available At least a third of the blood supply in the world is used to transfuse 1–2 units of packed red blood cells for each intervention and most clinical trials of blood substitutes have been carried out at this level of oxygen carrying capacity (OCC restoration. However, the increase of oxygenation achieved is marginal or none at all for molecular hemoglobin (Hb products, due to their lingering vasoactivity. This has provided the impetus for the development of “oxygen therapeutics” using Hb-based molecules that have high oxygen affinity and target delivery of oxygen to anoxic areas. However it is still unclear how these oxygen carriers counteract or mitigate the functional effects of anemia due to obstruction, vasoconstriction and under-perfusion. Indeed, they are administered as a low dosage/low volume therapeutic Hb (subsequently further diluted in the circulatory pool and hence induce extremely small OCC changes. Hyperviscous plasma expanders provide an alternative to oxygen therapeutics by increasing the oxygen delivery capacity (ODC; in anemia they induce supra-perfusion and increase tissue perfusion (flow by as much as 50%. Polyethylene glycol conjugate albumin (PEG-Alb accomplishes this by enhancing the shear thinning behavior of diluted blood, which increases microvascular endothelial shear stress, causes vasodilation and lowering peripheral vascular resistance thus facilitating cardiac function. Induction of supra-perfusion takes advantage of the fact that ODC is the product of OCC and blood flow and hence can be maintained by increasing either or both. Animal studies suggest that this approach may save a considerable fraction of the blood supply. It has an additional benefit of enhancing tissue clearance of toxic metabolites.

  17. High time resolution measurements of the thermosphere from Fabry-Perot Interferometer measurements of atomic oxygen

    Directory of Open Access Journals (Sweden)

    E. A. K. Ford

    2007-06-01

    Full Text Available Recent advances in the performance of CCD detectors have enabled a high time resolution study of the high latitude upper thermosphere with Fabry-Perot Interferometers (FPIs to be performed. 10-s integration times were used during a campaign in April 2004 on an FPI located in northern Sweden in the auroral oval. The FPI is used to study the thermosphere by measuring the oxygen red line emission at 630.0 nm, which emits at an altitude of approximately 240 km. Previous time resolutions have been 4 min at best, due to the cycle of look directions normally observed. By using 10 s rather than 40 s integration times, and by limiting the number of full cycles in a night, high resolution measurements down to 15 s were achievable. This has allowed the maximum variability of the thermospheric winds and temperatures, and 630.0 nm emission intensities, at approximately 240 km, to be determined as a few minutes. This is a significantly greater variability than the often assumed value of 1 h or more. A Lomb-Scargle analysis of this data has shown evidence of gravity wave activity with waves with short periods. Gravity waves are an important feature of mesosphere-lower thermosphere (MLT dynamics, observed using many techniques and providing an important mechanism for energy transfer between atmospheric regions. At high latitudes gravity waves may be generated in-situ by localised auroral activity. Short period waves were detected in all four clear nights when this experiment was performed, in 630.0 nm intensities and thermospheric winds and temperatures. Waves with many periodicities were observed, from periods of several hours, down to 14 min. These waves were seen in all parameters over several nights, implying that this variability is a typical property of the thermosphere.

  18. Assessment of pancreatic blood flow with positron emission tomography and oxygen-15 water

    International Nuclear Information System (INIS)

    Kubo, Soichi; Yamamoto, Kazutaka; Magata, Yasutaka; Iwasaki, Yasushi; Tamaki, Nagara; Yonekura, Yoshiharu; Konishi, Junji

    1991-01-01

    Dynamic positron emission tomography (PET) was performed following an intravenous bolus injection of 15 O-water for the assessment of regional pancreatic blood flow in 4 normal volunteers and 11 patients with pancreatic cancer. The regional pancreatic blood flow index (PFI) was calculated by the autoradiographic method assuming the time-activity curves of the aorta as an input function. The mean PFI value was 0.514±0.098 in the normal pancreas but it was decrease in the pancreatic cancer (0.247±0.076) (p 15 O-water permits quantitative assessment of pancreatic blood flow which decreased in both pancreatic cancer and concomitant obstructive pancreatitis distal to the tumor. (author)

  19. High blood oxygen affinity in the air-breathing swamp eel Monopterus albus.

    Science.gov (United States)

    Damsgaard, Christian; Findorf, Inge; Helbo, Signe; Kocagoz, Yigit; Buchanan, Rasmus; Huong, Do Thi Thanh; Weber, Roy E; Fago, Angela; Bayley, Mark; Wang, Tobias

    2014-12-01

    The Asian swamp eel (Monopterus albus, Zuiew 1793) is a facultative air-breathing fish with reduced gills. Previous studies have shown that gas exchange seems to occur across the epithelium of the buccopharyngeal cavity, the esophagus and the integument, resulting in substantial diffusion limitations that must be compensated by adaptations in others steps of the O₂ transport system to secure adequate O₂ delivery to the respiring tissues. We therefore investigated O₂ binding properties of whole blood, stripped hemoglobin (Hb), two major isoHb components and the myoglobin (Mb) from M. albus. Whole blood was sampled using indwelling catheters for blood gas analysis and determination of O₂ equilibrium curves. Hb was purified to assess the effects of endogenous allosteric effectors, and Mb was isolated from heart and skeletal muscle to determine its O₂ binding properties. The blood of M. albus has a high O₂ carrying capacity [hematocrit (Hct) of 42.4±4.5%] and binds O₂ with an unusually high affinity (P₅₀=2.8±0.4mmHg at 27°C and pH7.7), correlating with insensitivity of the Hb to the anionic allosteric effectors that normally decrease Hb-O₂ affinity. In addition, Mb is present at high concentrations in both heart and muscle (5.16±0.99 and 1.08±0.19mg ∙ g wet tissue⁻¹, respectively). We suggest that the high Hct and high blood O₂ affinity serve to overcome the low diffusion capacity in the relatively inefficient respiratory surfaces, while high Hct and Mb concentration aid in increasing the O₂ flux from the blood to the muscles. Copyright © 2014 Elsevier Inc. All rights reserved.

  20. Blood pulsation measurement using cameras operating in visible light: limitations.

    Science.gov (United States)

    Koprowski, Robert

    2016-10-03

    The paper presents an automatic method for analysis and processing of images from a camera operating in visible light. This analysis applies to images containing the human facial area (body) and enables to measure the blood pulse rate. Special attention was paid to the limitations of this measurement method taking into account the possibility of using consumer cameras in real conditions (different types of lighting, different camera resolution, camera movement). The proposed new method of image analysis and processing was associated with three stages: (1) image pre-processing-allowing for the image filtration and stabilization (object location tracking); (2) main image processing-allowing for segmentation of human skin areas, acquisition of brightness changes; (3) signal analysis-filtration, FFT (Fast Fourier Transformation) analysis, pulse calculation. The presented algorithm and method for measuring the pulse rate has the following advantages: (1) it allows for non-contact and non-invasive measurement; (2) it can be carried out using almost any camera, including webcams; (3) it enables to track the object on the stage, which allows for the measurement of the heart rate when the patient is moving; (4) for a minimum of 40,000 pixels, it provides a measurement error of less than ±2 beats per minute for p lighting; (5) analysis of a single image takes about 40 ms in Matlab Version 7.11.0.584 (R2010b) with Image Processing Toolbox Version 7.1 (R2010b).

  1. Context-aware patient guidance during blood pressure self-measurement

    DEFF Research Database (Denmark)

    Sandager, Puk; Lindahl, Camilla; Schlütter, Jacob Mørup

    2013-01-01

    The importance of accurate measurement of blood pressure in the screening and management of hypertension during pregnancy is well established. Blood pressure levels can be measured manually by healthcare staff or by using a blood pressure self-measurement device, either at home or in the clinic...... the blood pressure self-measurement process. Preliminary results indicate that such active and context-aware guidance leads to more reliable measurements by inhibiting non-adherent patient behavior...

  2. Student measurement of blood pressure using a simulator arm compared with a live subject's arm.

    Science.gov (United States)

    Lee, Jennifer J; Sobieraj, Diana M; Kuti, Effie L

    2010-06-15

    To compare accuracy of blood pressure measurements using a live subject and a simulator arm, and to determine students' preferences regarding measurement. This was a crossover study comparing blood pressure measurements from a live subject and a simulator arm. Students completed an anonymous survey instrument defining opinions on ease of measurement. Fifty-seven students completed blood pressure measurements on live subjects while 72 students completed blood pressure measurements using the simulator arm. There were no significant systematic differences between the 2 measurement techniques. Systolic blood pressure measurements from a live subject arm were less likely to be within 4 mm Hg compared with measurements of a simulator arm. Diastolic blood pressure measurements were not significantly different between the 2 techniques. Accuracy of student measurement of blood pressure using a simulator arm was similar to the accuracy with a live subject. There was no difference in students' preferences regarding measurement techniques.

  3. Quantitative Analysis of Oxygen Gas Exhausted from Anode through In Situ Measurement during Electrolytic Reduction

    Directory of Open Access Journals (Sweden)

    Eun-Young Choi

    2017-01-01

    Full Text Available Quantitative analysis by in situ measurement of oxygen gas evolved from an anode was employed to monitor the progress of electrolytic reduction of simulated oxide fuel in a molten Li2O–LiCl salt. The electrolytic reduction of 0.6 kg of simulated oxide fuel was performed in 5 kg of 1.5 wt.% Li2O–LiCl molten salt at 650°C. Porous cylindrical pellets of simulated oxide fuel were used as the cathode by loading a stainless steel wire mesh cathode basket. A platinum plate was employed as the anode. The oxygen gas evolved from the anode was exhausted to the instrumentation for in situ measurement during electrolytic reduction. The instrumentation consisted of a mass flow controller, pump, wet gas meter, and oxygen gas sensor. The oxygen gas was successfully measured using the instrumentation in real time. The measured volume of the oxygen gas was comparable to the theoretically calculated volume generated by the charge applied to the simulated oxide fuel.

  4. Trace-element measurement in human blood samples

    International Nuclear Information System (INIS)

    Hamidian, M.R.; Ebrahimi-Fakhar, F.

    1992-01-01

    It is conceivable that some essential elements such as zinc, iron, calcium, copper, phosphorus, selenium, etc., have a major impact on biological and metabolical functions in the human body. The concentration of these elements is normally very minute and changes within a naturally set tolerance. The accurate measurement of these elements in biological samples, such as in blood, is one of the objectives of medical physics in diagnosis. There are many sophisticated methods to measure the accurate amount of each element in biological samples. The methods used in this project are a combination of proton-induced X-ray emission (PIXE) and neutron activation analysis (NAA). The PIXE and NAA are fast and reliable techniques for multielement analysis at the level of parts per million and less

  5. Flexible Sheet-Type Sensor for Noninvasive Measurement of Cellular Oxygen Metabolism on a Culture Dish.

    Directory of Open Access Journals (Sweden)

    Mari Kojima

    Full Text Available A novel flexible sensor was developed for the noninvasive oxygen metabolism measurement of cultivated cells and tissues. This device is composed of a transparent double-layered polymer sheet of ethylene-vinyl alcohol (EVOH and poly(dimethylsiloxane (PDMS having an array of microhole structures of 90 μm diameter and 50 μm depth on its surface. All the microhole structures were equipped with a 1-μm-thick optical chemical sensing layer of platinum porphyrin-fluoropolymer on their bottom. The three-dimensional microstructures of the sensor were fabricated by a newly developed simple and low-cost production method named self-aligned hot embossing. The device was designed to be attached slightly above the cells cultivated on a dish to form a temporarily closed microspace over the target cells during measurement. Since the change in oxygen concentration is relatively fast in the microcompartmentalized culture medium, a rapid evaluation of the oxygen consumption rate is possible by measuring the phosphorescence lifetime of the platinum porphyrin-fluoropolymer. The combined use of the device and an automated optical measurement system enabled the high-throughput sensing of cellular oxygen consumption (100 points/min. We monitored the oxygen metabolism of the human breast cancer cell line MCF7 on a Petri dish and evaluated the oxygen consumption rate to be 0.72 ± 0.12 fmol/min/cell. Furthermore, to demonstrate the utility of the developed sensing system, we demonstrated the mapping of the oxygen consumption rate of rat brain slices and succeeded in visualizing a clear difference among the layer structures of the hippocampus, i.e., the cornu ammonis (CA1 and CA3 and dentate gyrus (DG.

  6. Spatial and temporal oxygen distribution measured with oxygen microsensors in growing media with different levels of compaction

    DEFF Research Database (Denmark)

    Dresbøll, Dorte; Thorup-Kristensen, Kristian

    2011-01-01

    % compacted, respectively). The water distribution in the pot was determined as water content (gcm-3) in the top, middle and bottom layers of the peat. Oxygen content was also determined after a standard subirrigation cycle and after excessive irrigation where the bottom of the pots were left waterlogged...... for 24 h. Measurements were carried out at 5.5 weeks during the production phase and at 12 weeks at the end of the production. The results showed that with increasing compaction and density, more water was transported to the upper layers of the pot. After a standard irrigation cycle there was no effect...... in growing media and how this was affected by the physical characteristics of the growing media....

  7. Oxygen Therapy

    Directory of Open Access Journals (Sweden)

    Bonnie Solmes

    2000-01-01

    Full Text Available LTOT is prescribed for people with chronic lung disease in whom there is a decrease in the ability of the lungs to supply enough oxygen to the body. The heart is obliged to pump faster to meet the body's oxygen requirements. This may place undue stress on the heart, resulting in palpitations, dizziness and fatigue. A low oxygen level in arterial blood is also harmful to the heart, the brain and the pulmonary blood vessels. Oxygen therapy is used to break this cycle. A person with low blood oxygen will often be able to accomplish more with less fatigue with the help of supplemental oxygen therapy. Shortness of breath is a mechanical problem resulting from the effects of chronic obstructive pulmonary disease. Oxygen therapy may or may not reduce shortness of breath, but it will help the lungs and heart to function with less stress.

  8. Development of micro-coulometry for measuring oxygen content in copper oxides

    International Nuclear Information System (INIS)

    Sato, Fumiaki; Fujihara, Masaaki; Kambe, Shiro; Ishii, Osamu

    2006-01-01

    A micro-coulometry system was newly developed and employed for measuring the oxygen content in copper oxides using a reduced amount of material. To achieve this reduction in sample size, Ar flow rate, and coulometric current were optimized. When using 5.0 mg of YBa 2 Cu 3 O 6.71 , which is about 1/10 the amount used in conventional coulometry, the oxygen content was successfully determined to be 6.68 ± 0.03, Ar flow rate, and coulometric current were 0.1 l/min, and 1.0 mA, respectively. It was found to be necessary to continue to pass Ar through the solution before coulometry more than ten minutes and during the coulometric measurement. This method will be useful for measuring the oxygen content of oxide samples smaller than 10 mg, i.e. oxide materials produced in small quantities for electronic applications

  9. Clinical assessment of the accuracy of blood glucose measurement devices.

    Science.gov (United States)

    Pfützner, Andreas; Mitri, Michael; Musholt, Petra B; Sachsenheimer, Daniela; Borchert, Marcus; Yap, Andrew; Forst, Thomas

    2012-04-01

    Blood glucose meters for patient self-measurement need to comply with the accuracy standards of the ISO 15197 guideline. We investigated the accuracy of the two new blood glucose meters BG*Star and iBG*Star (Sanofi-Aventis) in comparison to four other competitive devices (Accu-Chek Aviva, Roche Diagnostics; FreeStyle Freedom Lite, Abbott Medisense; Contour, Bayer; OneTouch Ultra 2, Lifescan) at different blood glucose ranges in a clinical setting with healthy subjects and patients with type 1 and type 2 diabetes. BGStar and iBGStar are employ dynamic electrochemistry, which is supposed to result in highly accurate results. The study was performed on 106 participants (53 female, 53 male, age (mean ± SD): 46 ± 16 years, type 1: 32 patients, type 2: 34 patients, and 40 healthy subjects). Two devices from each type and strips from two different production lots were used for glucose assessment (∼200 readings/meter). Spontaneous glucose assessments and glucose or insulin interventions under medical supervision were applied to perform measurements in the different glucose ranges in accordance with the ISO 15197 requirements. Sample values 400 mg/dL were prepared by laboratory manipulations. The YSI glucose analyzer (glucose oxidase method) served as the standard reference method which may be considered to be a limitation in light of glucose hexokinase-based meters. For all devices, there was a very close correlation between the glucose results compared to the YSI reference method results. The correlation coefficients were r = 0.995 for BGStar and r = 0.992 for iBGStar (Aviva: 0.995, Freedom Lite: 0.990, Contour: 0.993, Ultra 2: 0.990). Error-grid analysis according to Parkes and Clarke revealed both 100% of the readings to be within the clinically acceptable areas (Clarke: A + B with BG*Star (100 + 0), Aviva (97 + 3), and Contour (97 + 3); and 99.5% with iBG*Star (97.5 + 2), Freedom Lite (98 + 1.5), and Ultra 2 (97.5 + 2

  10. MR vascular fingerprinting: A new approach to compute cerebral blood volume, mean vessel radius, and oxygenation maps in the human brain.

    Science.gov (United States)

    Christen, T; Pannetier, N A; Ni, W W; Qiu, D; Moseley, M E; Schuff, N; Zaharchuk, G

    2014-04-01

    In the present study, we describe a fingerprinting approach to analyze the time evolution of the MR signal and retrieve quantitative information about the microvascular network. We used a Gradient Echo Sampling of the Free Induction Decay and Spin Echo (GESFIDE) sequence and defined a fingerprint as the ratio of signals acquired pre- and post-injection of an iron-based contrast agent. We then simulated the same experiment with an advanced numerical tool that takes a virtual voxel containing blood vessels as input, then computes microscopic magnetic fields and water diffusion effects, and eventually derives the expected MR signal evolution. The parameter inputs of the simulations (cerebral blood volume [CBV], mean vessel radius [R], and blood oxygen saturation [SO2]) were varied to obtain a dictionary of all possible signal evolutions. The best fit between the observed fingerprint and the dictionary was then determined by using least square minimization. This approach was evaluated in 5 normal subjects and the results were