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Sample records for high blood flow

  1. High speed optical holography of retinal blood flow

    CERN Document Server

    Pellizzari, Mathilde; Degardin, Julie; Sahel, Jose-Alain; Fink, Mathias; Paques, Michel; Atlan, Michael

    2016-01-01

    We performed non-invasive video imaging of retinal blood flow in a pigmented rat by holographic interferometry of near-infrared laser light backscattered by retinal tissue, beating against an off-axis reference beam sampled at a frame rate of 39 kHz with a high throughput camera. Local Doppler contrasts emerged from the envelopes of short-time Fourier transforms and the phase of autocorrelation functions of holograms rendered by Fresnel transformation. This approach permitted imaging of blood flow in large retinal vessels (30 microns diameter) over 400 by 400 pixels with a spatial resolution of 8 microns and a temporal resolution of 6.5 ms.

  2. Abnormal blood flow in the sublingual microcirculation at high altitude

    NARCIS (Netherlands)

    Martin, D.S.; Ince, C.; Goedhart, P.; Levett, D.Z.H.; Grocott, M.P.W.

    2009-01-01

    We report the first direct observations of deranged microcirculatory blood flow at high altitude, using sidestream dark-field imaging. Images of the sublingual microcirculation were obtained from a group of 12 volunteers during a climbing expedition to Cho Oyu (8,201 m) in the Himalayas.

  3. High speed optical holography of retinal blood flow.

    Science.gov (United States)

    Pellizzari, M; Simonutti, M; Degardin, J; Sahel, J-A; Fink, M; Paques, M; Atlan, M

    2016-08-01

    We performed noninvasive video imaging of retinal blood flow in a pigmented rat by holographic interferometry of near-infrared laser light backscattered by retinal tissue, beating against an off-axis reference beam sampled at a frame rate of 39 kHz with a high throughput camera. Local Doppler contrasts emerged from the envelopes of short-time Fourier transforms and the phase of autocorrelation functions of holograms rendered by Fresnel transformation. This approach permitted imaging of blood flow in large retinal vessels (∼30 microns diameter) over 400×400  pixels with a spatial resolution of ∼8 microns and a temporal resolution of ∼6.5  ms.

  4. A Method for Gray-Scale Imaging of Blood Flow Using High-Frequency Ultrasound.

    Science.gov (United States)

    Yang, Jun; Pang, Chao; Song, Xue-Dong; Gao, Xuan

    2017-07-01

    This paper presents a new method that complements current techniques available in the high-frequency blood imaging field. A comprehensive scattering model was established to determine the feasibility and frequency range of the blood flow imaging of superficial organs and tissues using high-frequency ultrasound. The transmitting and receiving modes and an algorithm were designed to obtain blood flow information based on differentiation between tissues and blood flow. The system was created and tested first with a model that simulates blood flow and was then used on human tissue. A fine-scale image of a blood vessel could be obtained with this system. Moreover, this method can obtain weak blood flow signal using single pulse rather than the traditional pulse-code method and maintains a high resolution that can be matched to high-frequency structural imaging. This study provides a reliable method for further applications related to diagnoses of superficial organs.

  5. Blood flow

    Science.gov (United States)

    ... the same time, the veins carry oxygen-poor blood (shown in blue) from the tissues back toward the heart. From there, it passes to the lungs to receive more oxygen. This cycle repeats itself when oxygen-rich blood returns to the heart from the lungs, which ...

  6. Clinical applications of high-speed blood flow measurements with diffuse correlation spectroscopy

    Science.gov (United States)

    Parthasarathy, Ashwin B.; Baker, Wesley B.; Gannon, Kimberly; Mullen, Michael T.; Detre, John A.; Yodh, Arjun G.

    2017-02-01

    Diffuse Correlation Spectroscopy (DCS) is an increasingly popular non-invasive optical technique to clinically measure deep tissue blood flow, albeit at slow measurement rates of 0.5-1 Hz. We recently reported the development of a new `fast' DCS instrument that continuously measures blood flow at 50-100 Hz (simultaneously from 8 channels), using conventional DCS sources/detectors, and optimized software computations. A particularly interesting result was our ability to optically record pulsatile micro-vascular blood flow waveforms, and therein readily identify high frequency features such as the dicrotic notch. Here, we showcase the utility and potential of high-speed measurements of blood flow (and arterial blood pressure) in a few clinical applications. First, we employ the fast-DCS instrumentation to measure cerebral autoregulation (CVAR) dynamics. Cerebral autoregulation refers to the mechanism by which cerebral blood flow (CBF) is maintained during fluctuations in blood pressure; CVAR is impaired in the injured brain. We derive an index of autoregulation by measuring the rates of decrease (and recovery) of blood flow and blood pressure following a sudden, induced change in systemic blood pressure (e.g., bilateral thigh cuff deflation). Our pilot experiments in healthy volunteers show that DCS measured rates of micro-vascular regulation are comparable to conventional large vessel regulatory metrics (e.g., measured with transcranial Doppler ultrasound). Second, we utilized pulsatile blood flow oscillations in cerebral arteries to estimate the critical closing pressure (CrCP), i.e., the arterial blood pressure at which CBF approaches zero. Pilot experiments in healthy subjects show good agreement between CrCP measured with DCS and transcranial Doppler ultrasound.

  7. Internal filtration, filtration fraction, and blood flow resistance in high- and low-flux dialyzers.

    Science.gov (United States)

    Schneditz, Daniel; Zierler, Edda; Vanholder, Raymond; Eloot, Sunny

    2014-01-01

    It was the aim to examine the fluid flow in blood and dialysate compartments of highly permeable hollow fiber dialyzers where internal filtration contributes to solute removal but where excessive filtration bears a risk of cell activation and damage. Flow characteristics of high- (HF) and low-flux (LF) dialyzers were studied in lab-bench experiments using whole bovine blood. Measurements obtained under different operating conditions and under zero net ultrafiltration were compared to theoretical calculations obtained from a mathematical model. Experimental resistances in the blood compartment were within ±2% of those calculated from the model when dialysate was used as a test fluid. With whole blood, the experimental resistances in the blood compartment were only 81.8 ± 2.8% and 83.7 ± 4.3% of those calculated for the LF and HF dialyzer, respectively. Surprisingly, measured blood flow resistance slightly but significantly decreased with increasing flow rate (p filtration fraction, while overall internal filtration increased. The increase in internal filtration when increasing blood flow is associated with a beneficial reduction in internal filtration fraction. Concerns of increased hemoconcentration when increasing blood flow therefore appear to be unwarranted.

  8. Effects of High-Intensity Blood Flow Restriction Exercise on Muscle Fatigue

    Directory of Open Access Journals (Sweden)

    Neto Gabriel R.

    2014-07-01

    Full Text Available Strength training combined with blood flow restriction (BFR have been used to improve the levels of muscle adaptation. The aim of this paper was to investigate the acute effect of high intensity squats with and without blood flow restriction on muscular fatigue levels. Twelve athletes (aged 25.95 ± 0.84 years were randomized into two groups: without Blood Flow Restriction (NFR, n = 6 and With Blood Flow Restriction (WFR, n = 6 that performed a series of free weight squats with 80% 1-RM until concentric failure. The strength of the quadriceps extensors was assessed in a maximum voluntary isometric contraction integrated to signals from the surface electromyogram. The average frequency showed significant reductions in the WFR group for the vastus lateralis and vastus medialis muscles, and intergroup only for the vastus medialis. In conclusion, a set of squats at high intensity with BFR could compromise muscle strength immediately after exercise, however, differences were not significant between groups.

  9. Blood flow regulation and oxygen uptake during high intensity forearm exercise.

    Science.gov (United States)

    Nyberg, Stian Kwak; Berg, Ole Kristian; Helgerud, Jan; Wang, Eivind

    2017-01-05

    The vascular strain is very high during heavy handgrip exercise, but the intensity and kinetics to reach peak blood flow, and peak oxygen uptake, are uncertain. We included 9 young (25±2yr) healthy males to evaluate blood flow and oxygen uptake responses during continuous dynamic handgrip exercise with increasing intensity. Blood flow was measured using Doppler-ultrasound and venous blood was drawn from a deep forearm vein to determine arteriovenous oxygen difference (a-vO2diff) during 6-minutes bouts of 60, 80 and 100% of maximal work rate (WRmax), respectively. Blood flow and oxygen uptake increased (pBlood velocity (49.5±11.5 cm∙sec(-1) to 58.1±11.6 cm∙sec(-1)) and brachial diameter (0.49±0.05cm to 0.50±0.06 cm) showed concomitant increases (pblood flow from 60% to 80%WRmax, while no differences were observed in a-vO2diff Shear rate also increased (pblood flow (60%WRmax:50±22s; 80%WRmax:51±20s; 100%WRmax:51±23s) than a-vO2diff (60%WRmax:29±9s; 80%WRmax:29±5s; 100%WRmax:20±5s), but not different from oxygen uptake (60%WRmax:44±25s; 80%WRmax:43±14s; 100%WRmax:41±32s). No differences were observed in MRT for blood flow or oxygen uptake with increased exercise intensity. In conclusion, when approaching maximal intensity, oxygen uptake appeared to reach a critical level at ~80% of WRmax and be regulated by blood flow. This implies that high, but not maximal, exercise intensity may be an optimal stimulus for shear stress-induced small muscle mass training adaptations.

  10. Fast blood flow visualization of high-resolution laser speckle imaging data using graphics processing unit.

    Science.gov (United States)

    Liu, Shusen; Li, Pengcheng; Luo, Qingming

    2008-09-15

    Laser speckle contrast analysis (LASCA) is a non-invasive, full-field optical technique that produces two-dimensional map of blood flow in biological tissue by analyzing speckle images captured by CCD camera. Due to the heavy computation required for speckle contrast analysis, video frame rate visualization of blood flow which is essentially important for medical usage is hardly achieved for the high-resolution image data by using the CPU (Central Processing Unit) of an ordinary PC (Personal Computer). In this paper, we introduced GPU (Graphics Processing Unit) into our data processing framework of laser speckle contrast imaging to achieve fast and high-resolution blood flow visualization on PCs by exploiting the high floating-point processing power of commodity graphics hardware. By using GPU, a 12-60 fold performance enhancement is obtained in comparison to the optimized CPU implementations.

  11. Rheology of red blood cells under flow in highly confined microchannels: I. effect of elasticity.

    Science.gov (United States)

    Lázaro, Guillermo R; Hernández-Machado, Aurora; Pagonabarraga, Ignacio

    2014-10-07

    We analyze the rheology of dilute red blood cell suspensions in pressure driven flows at low Reynolds number, in terms of the morphologies and elasticity of the cells. We focus on narrow channels of width similar to the cell diameter, when the interactions with the walls dominate the cell dynamics. The suspension presents a shear-thinning behaviour, with a Newtonian-behaviour at low shear rates, an intermediate region of strong decay of the suspension viscosity, and an asymptotic regime at high shear rates in which the effective viscosity converges to that of the solvent. We identify the relevant aspects of cell elasticity that contribute to the rheological response of blood at high confinement. In a second paper, we will explore the focusing of red blood cells while flowing at high shear rates and how this effect is controlled by the geometry of the channel.

  12. Unchanged cerebral blood flow and oxidative metabolism after acclimatization to high altitude

    DEFF Research Database (Denmark)

    Møller, Kirsten; Paulson, Olaf B; Hornbein, Thomas F.

    2002-01-01

    . At high altitude at rest, arterial carbon dioxide tension, oxygen saturation, and oxygen tension were significantly reduced, and arterial oxygen content was increased because of an increase in hemoglobin concentration. Global cerebral blood flow was similar in the four conditions. Cerebral oxygen delivery...

  13. Blood Flow in the Microcirculation

    Science.gov (United States)

    Secomb, Timothy W.

    2017-01-01

    The microcirculation is an extensive network of microvessels that distributes blood flow throughout living tissues. Reynolds numbers are much less than 1, and the equations of Stokes flow apply. Blood is a suspension of cells with dimensions comparable to microvessel diameters. Highly deformable red blood cells, which transport oxygen, have a volume concentration (hematocrit) of 40–45% in humans. In the narrowest capillaries, these cells move in single file with a surrounding lubricating layer of plasma. In larger vessels, the red blood cells migrate toward the centerline, reducing the resistance to blood flow. Vessel walls are coated with a layer of macromolecules that restricts flow. At diverging bifurcations, hematocrit is not evenly distributed in the downstream vessels. Other particles are driven toward the walls by interactions with red blood cells. These physiologically important phenomena are discussed here from a fluid mechanical perspective.

  14. Correlation analysis of high precision blood flow imaging in secondary parathyroid function in maintenance hemodialysis patients

    Institute of Scientific and Technical Information of China (English)

    Wen-Ze Du; Le Chen; Xiao-Yun Wu

    2016-01-01

    Objective:To investigate the value of high precision blood flow imaging (Fine-Flow) in secondary parathyroid function (SHPT) in patients with maintenance hemodialysis (MHD). Methods: A total of 95 MHD patients with SHPT in our hospital from January 2015 to June 2016 were selected as the research object. According to the Fine-Flow examination of parathyroid gland, 73 cases were divided into display group, 22 cases were not shown; Display group according to the hyperplasia of parathyroid diameter were divided into 1.5 cm group of 17 cases; display group according to the blood flow into the rich group of 41 cases, not rich group of 32 cases; according to whether calcification were divided into calcification group of 43 cases, non calcified group of 30 cases. CDFI was used for the anterior region of neck transverse and longitudinal scanning, check the thyroid and around the dorsal lobes.The size, echo, lesion number and blood flow were measured, parathyroid hormone (PTH), serum calcium (Ca), phosphorus (P), and calculate the Ca and P product (Ca×P) were measured.Results: PTH and Ca of the display group were significantly higher than that of the non display group, and differences in P and Ca×P were not statistically significant; Parathyroid diameter >1.5 cm PTH levels were significantly higher than the other three groups, diameter 1-1.5 cm group and >1.5 cm group Ca, diameter Ca×P was higher than that in group <5 cm and 0.5-1.0 cm group, difference in P of four groups was not statistical significant; group PTH, P, abundant blood flow Ca×P were not significantly higher than the rich group, difference in P of two groups was no statistical significance; group Ca was significantly higher than that of calcification calcification group, differences in PTH, P, Ca×P of the two groups were not statistically significant.Conclusions:MHD patients with SHPT, parathyroid Fine-Flow display rate is high, and has the characteristic performance. Its operation is simple, non

  15. Resting cerebral blood flow

    Science.gov (United States)

    Ances, B M.; Sisti, D; Vaida, F; Liang, C L.; Leontiev, O; Perthen, J E.; Buxton, R B.; Benson, D; Smith, D M.; Little, S J.; Richman, D D.; Moore, D J.; Ellis, R J.

    2009-01-01

    infection; FOV = field of view; GDS = global deficit score; HAART = highly active antiretroviral therapy; HAND = HIV-associated neurocognitive disorders; LN = lenticular nuclei; rCBF = resting cerebral blood flow; TE = echo time; TI = inversion time; TR = repetition time; VC = visual cortex. PMID:19720977

  16. Evaluation of a new high power, wide separation laser Doppler probe : Potential measurement of deeper tissue blood flow

    NARCIS (Netherlands)

    Clough, Geraldine; Chipperfield, Andrew; Byrne, Christopher; de Mul, Frits; Gush, Rodney

    2009-01-01

    Objective: To compare the output from a novel high power, wide separation laser Doppler flow probe (DP1-V2-HP, 4 mm, with IRLD20) with that of a standard flow probe (DP1-V2, 0.5 mm, with DRT4) (Moor UK) and to explore its potential for use in the noninvasive measurement of blood flow in deeper tissu

  17. Sodium hydrosulfide alleviated pulmonary vascular structural remodeling induced by high pulmonary blood flow in rats

    Institute of Scientific and Technical Information of China (English)

    Xiao-hui LI; Jun-bao DU; Ding-fang BU; Xiu-ying TANG; Chao-shu TANG

    2006-01-01

    Aim: To explore the possible role of endogenous hydrogen sulfide (H2S), a novel gasotransmitter, in the pathogenesis of pulmonary vascular structural remodeling (PVSR) induced by high pulmonary blood flow. Methods: Thirty-two Sprague-Dawley male rats were randomly divided into sham, shunt, sham+NaHS (a H2S donor) and shunt+NaHS groups. Rats in shunt and shunt+NaHS groups underwent an abdominal aorta-inferior vena cava shunt, and rats in shunt+NaHS and sham+NaHS groups were intraperitoneally injected with NaHS. PVSR was investigated using optical microscope and transmission electron microscope. Lung tissue H2S was evaluated by sulfide-sensitive electrodes. Nitric oxide synthase (NOS), heme oxygenase (HO-1), proliferative cell nuclear antigen (PCNA) and extracellular signal-regulated kinase (ERK) activation were analyzed by Western blotting. Results: After 11 weeks of shunting, PVSR developed with a decrease in lung tissue H2S production and an increase in nitric oxide (NO). However, lung tissue carbon monoxide (CO) did not change. After the treatment with NaHS for 11 weeks, H2S donor ameliorated PVSR and downregulated PCNA expression and ERK activation with an increase in lung tissue CO production and HO-1 protein expression but a decrease in NO production, NOS activity and eNOS protein expression in shunted rats. Conclusions: H2S exerted a regulatory effect on PVSR induced by high pulmonary blood flow. Meanwhile, H2S down-regulated the ERK/MAPK signal pathway, inhibited the NO/NOS pathway and enhanced the CO/HO pathway in rats with high pulmonary blood flow.

  18. Unilateral bicep curl hemodynamics: Low-pressure continuous vs high-pressure intermittent blood flow restriction.

    Science.gov (United States)

    Brandner, C R; Kidgell, D J; Warmington, S A

    2015-12-01

    Light-load exercise training with blood flow restriction (BFR) increases muscle strength and size. However, the hemodynamics of BFR exercise appear elevated compared with non-BFR exercise. This questions the suitability of BFR in special/clinical populations. Nevertheless, hemodynamics of standard prescription protocols for BFR and traditional heavy-load exercise have not been compared. We investigated the hemodynamics of two common BFR exercise methods and two traditional resistance exercises. Twelve young males completed four unilateral elbow flexion exercise trials in a balanced, randomized crossover design: (a) heavy load [HL; 80% one-repetition maximum (1-RM)]; (b) light load (LL; 20% 1-RM); and two other light-load trials with BFR applied (c) continuously at 80% resting systolic blood pressure (BFR-C) or (d) intermittently at 130% resting systolic blood pressure (BFR-I). Hemodynamics were measured at baseline, during exercise, and for 60-min post-exercise. Exercising heart rate, blood pressure, cardiac output, and rate-pressure product were significantly greater for HL and BFR-I compared with LL. The magnitude of hemodynamic stress for BFR-C was between that of HL and LL. These data show reduced hemodynamics for continuous low-pressure BFR exercise compared with intermittent high-pressure BFR in young healthy populations. BFR remains a potentially viable method to improve muscle mass and strength in special/clinical populations. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  19. Sodium hydrosulfide alleviates pulmonary artery collagen remodeling in rats with high pulmonary blood flow.

    Science.gov (United States)

    Li, Xiaohui; Du, Junbao; Jin, Hongfang; Geng, Bin; Tang, Chaoshu

    2008-11-01

    This study aimed to explore the effect of sodium hydrosulfide (NaHS) on pulmonary artery collagen remodeling in rats with high pulmonary blood flow. Thirty-two Sprague-Dawley rats were randomly divided into a sham group, shunt group, sham + NaHS (an H2S donor) group, and shunt + NaHS group. After 11 weeks of shunting, mean pulmonary artery pressure (MPAP), relative median area (RMA) of pulmonary arteries, H2S concentration in lung tissues, plasma endothelin-1 (ET-1) levels, and ET-1 mRNA in lung tissues were investigated. Collagen I and collagen III were evaluated by immunohistochemistry. Hydroxyproline assay and Sirius-red staining were performed. Matrix metalloproteinase-13 (MMP-13), tissue inhibitor of metalloproteinase-1 (TIMP-1), and connective tissue growth factor (CTGF) were evaluated by immunohistochemistry. After 11 weeks of shunting, rats showed a significant pulmonary hypertension and pulmonary artery collagen remodeling in association with a decrease in lung tissue H2S content. After NaHS treatment for 11 weeks, lung tissue H(2)S content was increased, whereas MPAP was attenuated and RMA was reduced. Meanwhile, pulmonary artery collagen I and collagen III protein expressions of intra-acinar pulmonary arteries were inhibited, but MMP-13/TIMP-1 ratio was augmented with a decreased plasma ET-1 content and lung tissue ET-1mRNA and CTGF expressions. The downregulation of H(2)S is involved in the development of pulmonary artery collagen remodeling induced by high pulmonary blood flow.

  20. Role of nitric oxide and prostanoids in the regulation of leg blood flow and blood pressure in humans with essential hypertension: effect of high-intensity aerobic training

    DEFF Research Database (Denmark)

    Nyberg, Michael Permin; Jensen, Lasse Gliemann; Thaning, Pia

    2012-01-01

    We examined the role of nitric oxide (NO) and prostanoids in the regulation of leg blood flow and systemic blood pressure before and after 8 weeks of aerobic high-intensity training in individuals with essential hypertension (n=10) and matched healthy control subjects (n=11). Hypertensive subjects...

  1. Blood flow and microgravity

    Science.gov (United States)

    Bureau, Lionel; Coupier, Gwennou; Dubois, Frank; Duperray, Alain; Farutin, Alexander; Minetti, Christophe; Misbah, Chaouqi; Podgorski, Thomas; Tsvirkun, Daria; Vysokikh, Mikhail

    2017-01-01

    The absence of gravity during space flight can alter cardio-vascular functions partially due to reduced physical activity. This affects the overall hemodynamics, and in particular the level of shear stresses to which blood vessels are submitted. Long-term exposure to space environment is thus susceptible to induce vascular remodeling through a mechanotransduction cascade that couples vessel shape and function with the mechanical cues exerted by the circulating cells on the vessel walls. Central to such processes, the glycocalyx - i.e. the micron-thick layer of biomacromolecules that lines the lumen of blood vessels and is directly exposed to blood flow - is a major actor in the regulation of biochemical and mechanical interactions. We discuss in this article several experiments performed under microgravity, such as the determination of lift force and collective motion in blood flow, and some preliminary results obtained in artificial microfluidic circuits functionalized with endothelium that offer interesting perspectives for the study of the interactions between blood and endothelium in healthy condition as well as by mimicking the degradation of glycocalyx caused by long space missions. A direct comparison between experiments and simulations is discussed. xml:lang="fr"

  2. Cerebral blood-flow tomography

    DEFF Research Database (Denmark)

    Lassen, N A; Henriksen, L; Holm, S

    1983-01-01

    Tomographic maps of local cerebral blood flow (CBF) were obtained with xenon-133 and with isopropyl-amphetamine-iodine-123 (IMP) in 11 subjects: one normal, two tumor cases, and eight cerebrovascular cases. A highly sensitive four-face, rapidly rotating, single-photon emission tomograph was used....

  3. Pulmonary blood flow and its distribution in highly trained endurance athletes and healthy control subjects

    NARCIS (Netherlands)

    I. Heinonen (Ilkka); M.J. Savolainen (Markku); C. Han (Chunlei); J. Kemppainen (Jukka); V. Oikonen (Vesa); M. Luotolahti (Matti); D.J.G.M. Duncker (Dirk); D. Merkus (Daphne); J. Knuuti (Juhani); K.K. Kalliokoski (Kari)

    2013-01-01

    textabstractPulmonary blood flow (PBF) is an important determinant of endurance sports performance, yet studies investigating adaptations of the pulmonary circulation in athletes are scarce. In the present study, we investigated PBF, its distribution, and heterogeneity at baseline and during intrave

  4. Changes in mean cerebral blood flow velocity during cognitive task-induced cerebral fatigue in high performance fighter pilots

    Institute of Scientific and Technical Information of China (English)

    Yongsheng Chen

    2008-01-01

    BACKGROUND: Several studies have demonstrated that sustained cognitive tasks can induce cognitive fatigue and that the mean cerebral blood flow velocity changes in some cerebral regions during cerebral fatigue. OBJECTIVE: To dynamically monitor the changes in mean cerebral blood flow velocity in different brain regions of high performance fighter pilots during mental arithmetic tasks and consecutive performance tasks. DESIGN, TIME AND SETTING: The present neurophysiological trial, based on controlled observation, was performed at the Laboratory of Neurophysiology, Institute of Aviation Medicine, Air Force of China between January 2003 and December 2005. PARTICIPANTS: Forty-five males, high performance fighter pilots, averaging (27.6 ± 2.5) years, were recruited for this study. METHODS: The mean cerebral blood flow velocity in the anterior cerebral artery, middle cerebral artery, and posterior cerebral artery of subjects was dynamically tested using transcranial Doppler during 5- hour mental arithmetic tasks and during 5- hour consecutive performance tasks. The neurobehavioral ability index was analyzed throughout each trial according to the number of correct responses, false responses, and lost responses. Simultaneously, cerebral cognitive fatigue-induced lethargy was assessed by the Stanford Sleepiness Scale. MAIN OUTCOME MEASURES: Changes in mean cerebral blood flow velocity in the anterior cerebral artery, middle cerebral artery, and posterior cerebral artery; neurobehavioral ability index of mental arithmetic and consecutive performance tasks; Stanford Sleepiness Scale scores. RESULTS: During mental arithmetic tasks, the mean cerebral blood flow velocity in the anterior cerebral artery increased during hour 2 and decreased after hour 4. There was no significant change in mean cerebral blood flow velocity in the middle cerebral artery and posterior cerebral artery. During hour 4, cerebral cognitive fatigue was observed and, simultaneously, Stanford Sleepiness

  5. New method for measuring myocardial blood flow by high resolution scintigraphy in the excised dog heart.

    Science.gov (United States)

    Hung, C Y; Burow, R D; Scherlag, B J; Basmadjian, G P; Lazzara, R

    1986-10-01

    The standard method for measuring myocardial blood flow (MBF) with radioactive microspheres requires processing of selected tissue samples usually from the excised heart, and consequent loss of exact relation to myocardial morphology. A computer-based image processing method was developed by using [99mTc]microspheres (mean particle size 20 microns) for quantitative analysis of MBF in 25 dogs. A computer-controlled gamma camera was used to obtain the images of radioactive microsphere distribution in transaxial slices of the ex vivo heart. Any portion of these slice images could be quantitated by using a computer program based on modification of the formula for determining MBF by the standard microsphere method. Regional myocardial perfusion calculated by this technique correlated well with values obtained with reference microspheres (r = 0.96) over a broad range of MBF. The results show that our new method, accurately and with high resolution, delineated zones of differing MBF and confirmed the increase of MBF in surviving myocardium with healing.

  6. Quantitative comparison of myocardial blood flow in normal and infarcted hearts by high resolution scintigraphy

    Energy Technology Data Exchange (ETDEWEB)

    Hung, C.Y.; Burow, R.D.; Scherlag, B.J.; Basmadjian, G.P.; Lazzara, R.

    1984-01-01

    The standard method for measuring myocardial blood flow (MBF) with radioactive microspheres requires processing of selected tissue samples and consequent loss of exact relation to myocardial morphology. Also, in myocardial infarction (MI) there are inaccuracies due to overlap of tissues from borders of normal and MI. A new method uses Tc-99m labeled microspheres (20..mu..) which were injected into the left atrium in 18 normal dogs and 12 dogs with MI (5 had 1 day and 7 had 4 day old MI). The excised hearts were rinsed and frozen before ''bread-loaf'' sections, 3 mm thick, were cut. Images were acquired on a gamma camera with a volume resolution of 12 mm/sup 3/. A computer program for determining MBF was checked against the conventional microsphere method. The volume resolution of the latter method was 100 mm/sup 3/. The correlation coefficient between the two methods was r=0.96. Average MBF for a given section of normal RV and LV was 95 +- 13 and 119 +- 15 ml/min/100 g of tissue, respectively. Average MBF was compared in normal LV and from ischemic epicardium (IsZ) of the central MI and endocardial infarcted zone (IZ). The authors' new method, accurately and with high resolution, delineates zones of differing MBF and confirms the increase of MBF in surviving myocardium with healing.

  7. New method for measuring myocardial blood flow by high resolution scintigraphy in the excised dog heart

    Energy Technology Data Exchange (ETDEWEB)

    Hung, C.Y.; Burow, R.D.; Scherlag, B.J.; Basmadjian, G.P.; Lazzara, R.

    1986-10-01

    The standard method for measuring myocardial blood flow (MBF) with radioactive microspheres requires processing of selected tissue samples usually from the excised heart, and consequent loss of exact relation to myocardial morphology. A computer-based image processing method was developed by using (99mTc)microspheres (mean particle size 20 microns) for quantitative analysis of MBF in 25 dogs. A computer-controlled gamma camera was used to obtain the images of radioactive microsphere distribution in transaxial slices of the ex vivo heart. Any portion of these slice images could be quantitated by using a computer program based on modification of the formula for determining MBF by the standard microsphere method. Regional myocardial perfusion calculated by this technique correlated well with values obtained with reference microspheres (r = 0.96) over a broad range of MBF. The results show that our new method, accurately and with high resolution, delineated zones of differing MBF and confirmed the increase of MBF in surviving myocardium with healing.

  8. High-NaCl intake impairs dynamic autoregulation of renal blood flow in ANG II-infused rats

    DEFF Research Database (Denmark)

    Saeed, Aso; Dibona, Gerald F; Marcussen, Niels

    2010-01-01

    The aim of this study was to investigate dynamic autoregulation of renal blood flow (RBF) in ANG II-infused rats and the influence of high-NaCl intake. Sprague-Dawley rats received ANG II (250 ng·kg(-1)·min(-1) sc) or saline vehicle (sham) for 14 days after which acute renal clearance experiments...

  9. High-NaCl diet impairs dynamic renal blood flow autoregulation in rats with adenine-induced chronic renal failure

    DEFF Research Database (Denmark)

    Saeed, Aso; DiBona, Gerald F; Grimberg, Elisabeth

    2014-01-01

    This study examined the effects of 2 wk of high-NaCl diet on kidney function and dynamic renal blood flow autoregulation (RBFA) in rats with adenine-induced chronic renal failure (ACRF). Male Sprague-Dawley rats received either chow containing adenine or were pair-fed an identical diet without ad...

  10. Velocity field measurements of valvular blood flow in a human superficial vein using high-frequency ultrasound speckle image velocimetry.

    Science.gov (United States)

    Nam, Kweon-Ho; Yeom, Eunseop; Ha, Hojin; Lee, Sang-Joon

    2012-01-01

    This study aims to investigate the blood flow around the perivalvular area in a human superficial vein using high-frequency ultrasound (HFUS) speckle image velocimetry. HFUS B-mode images were captured from the superficial veins of human lower extremity with a 35-MHz transducer. To measure the instantaneous velocity fields of blood flow, a cross-correlation particle image velocimetry (PIV) algorithm was applied to two B-mode images that were captured consecutively. The echo speckles of red blood cells (RBCs) were used as flow tracers. In the vicinity of the venous valve, the opening and closing motions of valve cusps were simultaneously visualized with the phasic variation of velocity fields. Large-scale vortices were observed behind the sinus pockets while the main bloodstream was directed proximally. This measurement technique combining PIV algorithm and HFUS B-mode imaging was found to be unique and useful for investigating the hemodynamic characteristics of blood flow in the perivalvular area and for diagnosing venous insufficiency and valve abnormality in superficial blood vessels.

  11. Determination of micro-litre volumes with high accuracy for flow cytometric blood cell counting

    Science.gov (United States)

    Reitz, S.; Kummrow, A.; Kammel, M.; Neukammer, J.

    2010-07-01

    We have gravimetrically calibrated the volumes dispensed by 1 mL syringes in the range between 1 µL and 100 µL using ultra-pure water. Protocols are based on series of consecutive difference measurements of masses in order to precisely compensate for evaporation, being the most important disturbing quantity. We determined expanded uncertainties of volume measurements for glass syringes of typically 0.2% (expansion factor 2) when dispensing volumes of 10 µL. For polypropylene syringes, selected with respect to the manufacturer, expanded uncertainties of 0.25% (expansion factor 2) were observed. Calibrated syringes were applied for measuring concentrations of blood cells in a flow cytometer demonstrating the capability to determine reference measurement values. Since the direct interaction of blood cells and syringe walls may lead to cell adhesion, glass syringes as well as (disposable) polypropylene syringes were calibrated.

  12. Rheology of red blood cells under flow in highly confined microchannels. II. Effect of focusing and confinement.

    Science.gov (United States)

    Lázaro, Guillermo R; Hernández-Machado, Aurora; Pagonabarraga, Ignacio

    2014-10-07

    We study the focusing of red blood cells and vesicles in pressure-driven flows in highly confined microchannels (10-30 μm), identifying the control parameters that dictate the cell distribution along the channel. Our results show that an increase in the flow velocity leads to a sharper cell distribution in a lateral position of the channel. This position depends on the channel width, with cells flowing at outer (closer to the walls) positions in thicker channels. We also study the relevance of the object shape, exploring the different behaviour of red blood cells and different vesicles. We also analyze the implications of these phenomena in the cell suspension rheology, highlighting the crucial role of the wall confinement in the rheological properties of the suspension.

  13. Hypertension (High Blood Pressure)

    Science.gov (United States)

    ... Surgery? A Week of Healthy Breakfasts Shyness Hypertension (High Blood Pressure) KidsHealth > For Teens > Hypertension (High Blood Pressure) Print ... rest temperature diet emotions posture medicines Why Is High Blood Pressure Bad? High blood pressure means a person's heart ...

  14. Magnetohydrodynamics of blood flow.

    Science.gov (United States)

    Keltner, J R; Roos, M S; Brakeman, P R; Budinger, T F

    1990-10-01

    The changes in hydrostatic pressure and electrical potentials across vessels in the human vasculature in the presence of a large static magnetic field are estimated to determine the feasibility of in vivo NMR spectroscopy at fields as high as 10 T.A 10-T magnetic field changes the vascular pressure in a model of the human vasculature by less than 0.2%. An exact solution to the magnetohydrodynamic equations describing a conducting fluid flowing transverse to a static magnetic field in a nonconducting, straight, circular tube is used. This solution is compared to an approximate solution that assumes that no magnetic fields are induced in the fluid and that has led previous investigators to predict significant biological effects from static magnetic fields. Experimental results show that the exact solution accurately predicts the magnetohydrodynamic slowing of 15% NaCl flowing transverse to 2.3- and 4.7-T magnetic fields for fluxes below 0.5 liter/min while the approximate solution predicts a much more retarded flow.

  15. Local Control of Blood Flow

    Science.gov (United States)

    Clifford, Philip S.

    2011-01-01

    Organ blood flow is determined by perfusion pressure and vasomotor tone in the resistance vessels of the organ. Local factors that regulate vasomotor tone include myogenic and metabolic autoregulation, flow-mediated and conducted responses, and vasoactive substances released from red blood cells. The relative importance of each of these factors…

  16. High Blood Cholesterol

    Science.gov (United States)

    ... version of this page please turn Javascript on. High Blood Cholesterol What is High Blood Cholesterol? What is Cholesterol? Cholesterol is a ... heart disease. If Your Blood Cholesterol Is Too High Too much cholesterol in your blood is called ...

  17. The involvement of ginseng berry extract in blood flow via regulation of blood coagulation in rats fed a high-fat diet

    Directory of Open Access Journals (Sweden)

    Min Hee Kim

    2017-04-01

    Conclusion: These results suggest the possibility that GBx can ameliorate blood flow by decreasing intima-media thickness via the regulation of blood coagulation factors related to lipid metabolites in rats fed a HFD.

  18. Pancreatic islet blood flow and its measurement.

    Science.gov (United States)

    Jansson, Leif; Barbu, Andreea; Bodin, Birgitta; Drott, Carl Johan; Espes, Daniel; Gao, Xiang; Grapensparr, Liza; Källskog, Örjan; Lau, Joey; Liljebäck, Hanna; Palm, Fredrik; Quach, My; Sandberg, Monica; Strömberg, Victoria; Ullsten, Sara; Carlsson, Per-Ola

    2016-05-01

    Pancreatic islets are richly vascularized, and islet blood vessels are uniquely adapted to maintain and support the internal milieu of the islets favoring normal endocrine function. Islet blood flow is normally very high compared with that to the exocrine pancreas and is autonomously regulated through complex interactions between the nervous system, metabolites from insulin secreting β-cells, endothelium-derived mediators, and hormones. The islet blood flow is normally coupled to the needs for insulin release and is usually disturbed during glucose intolerance and overt diabetes. The present review provides a brief background on islet vascular function and especially focuses on available techniques to measure islet blood perfusion. The gold standard for islet blood flow measurements in experimental animals is the microsphere technique, and its advantages and disadvantages will be discussed. In humans there are still no methods to measure islet blood flow selectively, but new developments in radiological techniques hold great hopes for the future.

  19. Endovascular blood flow measurement system

    Science.gov (United States)

    Khe, A. K.; Cherevko, A. A.; Chupakhin, A. P.; Krivoshapkin, A. L.; Orlov, K. Yu

    2016-06-01

    In this paper an endovascular measurement system used for intraoperative cerebral blood flow monitoring is described. The system is based on a Volcano ComboMap Pressure and Flow System extended with analogue-to-digital converter and PC laptop. A series of measurements performed in patients with cerebrovascular pathologies allows us to introduce “velocity-pressure” and “flow rate-energy flow rate” diagrams as important characteristics of the blood flow. The measurement system presented here can be used as an additional instrument in neurosurgery for assessment and monitoring of the operation procedure. Clinical data obtained with the system are used for construction of mathematical models and patient-specific simulations. The monitoring of the blood flow parameters during endovascular interventions was approved by the Ethics Committee at the Meshalkin Novosibirsk Research Institute of Circulation Pathology and included in certain surgical protocols for pre-, intra- and postoperative examinations.

  20. The Physics of Coronary Blood Flow

    CERN Document Server

    Zamir, M

    2005-01-01

    Coronary blood flow is blood flow to the heart for its own metabolic needs. In the most common form of heart disease there is a disruption in this flow because of obstructive disease in the vessels that carry the flow. The subject of coronary blood flow is therefore associated mostly with the pathophysiology of this disease, rarely with dynamics or physics. Yet, the system responsible for coronary blood flow, namely the "coronary circulation," is a highly sophisticated dynamical system in which the dynamics and physics of the flow are as important as the integrity of the conducting vessels. While an obstruction in the conducting vessels is a fairly obvious and clearly visible cause of disruption in coronary blood flow, any discord in the complex dynamics of the system can cause an equally grave, though less conspicuous, disruption in the flow. This book is devoted specifically to the dynamics and physics of coronary blood flow. While relevance to the clinical and pathophysiological issues is clearly maintaine...

  1. Neuromodulation of cerebral blood flow

    NARCIS (Netherlands)

    ter Laan, Mark

    2014-01-01

    Dit proefschrift behandelt de modulatie van de cerebrale doorbloeding (cerebral blood flow, CBF) door cervicale elektrische stimulatie en de aanname dat het sympathisch zenuwstelsel hierin een specifieke rol speelt. Enkele resultaten met cervicale ruggenmergsstimulatie (spinal cord stimulation, SCS)

  2. Regional differences in the cerebral blood flow velocity response to hypobaric hypoxia at high altitudes.

    Science.gov (United States)

    Feddersen, Berend; Neupane, Pritam; Thanbichler, Florian; Hadolt, Irmgard; Sattelmeyer, Vera; Pfefferkorn, Thomas; Waanders, Robb; Noachtar, Soheyl; Ausserer, Harald

    2015-11-01

    Symptoms of acute mountain sickness (AMS) may appear above 2,500 m altitude, if the time allowed for acclimatization is insufficient. As the mechanisms underlying brain adaptation to the hypobaric hypoxic environment are not fully understood, a prospective study was performed investigating neurophysiological changes by means of near infrared spectroscopy, electroencephalograpy (EEG), and transcranial doppler sonography at 100, 3,440 and 5,050 m above sea level in the Khumbu Himal, Nepal. Fourteen of the 26 mountaineers reaching 5,050 m altitude developed symptoms of AMS between 3,440 and 5,050 m altitude (Lake-Louise Score ⩾3). Their EEG frontal beta activity and occipital alpha activity increased between 100 and 3,440 m altitude, i.e., before symptoms appeared. Cerebral blood flow velocity (CBFV) in the anterior and middle cerebral arteries (MCAs) increased in all mountaineers between 100 and 3,440 m altitude. During further ascent to 5,050 altitude, mountaineers with AMS developed a further increase in CBFV in the MCA, whereas in all mountaineers CBFV decreased continuously with increasing altitude in the posterior cerebral arteries. These results indicate that hypobaric hypoxia causes different regional changes in CBFV despite similar electrophysiological changes.

  3. Using high resolution cardiac CT data to model and visualize patient-specific interactions between trabeculae and blood flow.

    Science.gov (United States)

    Kulp, Scott; Gao, Mingchen; Zhang, Shaoting; Qian, Zhen; Voros, Szilard; Metaxas, Dimitris; Axel, Leon

    2011-01-01

    In this paper, we present a method to simulate and visualize blood flow through the human heart, using the reconstructed 4D motion of the endocardial surface of the left ventricle as boundary conditions. The reconstruction captures the motion of the full 3D surfaces of the complex features, such as the papillary muscles and the ventricular trabeculae. We use visualizations of the flow field to view the interactions between the blood and the trabeculae in far more detail than has been achieved previously, which promises to give a better understanding of cardiac flow. Finally, we use our simulation results to compare the blood flow within one healthy heart and two diseased hearts.

  4. High Blood Pressure

    Science.gov (United States)

    ... normal blood pressure 140/90 or higher is high blood pressure Between 120 and 139 for the top number, ... prehypertension. Prehypertension means you may end up with high blood pressure, unless you take steps to prevent it. High ...

  5. High Blood Pressure (Hypertension)

    Science.gov (United States)

    ... Print Page Text Size: A A A Listen High Blood Pressure (Hypertension) Nearly 1 in 3 American adults has ... weight. How Will I Know if I Have High Blood Pressure? High blood pressure is a silent problem — you ...

  6. High Blood Cholesterol

    Science.gov (United States)

    ... page from the NHLBI on Twitter. What Is Cholesterol? To understand high blood cholesterol (ko-LES-ter- ... cholesterol from your body. What Is High Blood Cholesterol? High blood cholesterol is a condition in which ...

  7. Hyperhomocysteinemia decreases bone blood flow

    Directory of Open Access Journals (Sweden)

    Neetu T

    2011-01-01

    Full Text Available Neetu Tyagi*, Thomas P Vacek*, John T Fleming, Jonathan C Vacek, Suresh C TyagiDepartment of Physiology and Biophysics, School of Medicine, University of Louisville, Louisville, KY, USA *These authors have equal authorshipAbstract: Elevated plasma levels of homocysteine (Hcy, known as hyperhomocysteinemia (HHcy, are associated with osteoporosis. A decrease in bone blood flow is a potential cause of compromised bone mechanical properties. Therefore, we hypothesized that HHcy decreases bone blood flow and biomechanical properties. To test this hypothesis, male Sprague–Dawley rats were treated with Hcy (0.67 g/L in drinking water for 8 weeks. Age-matched rats served as controls. At the end of the treatment period, the rats were anesthetized. Blood samples were collected from experimental or control rats. Biochemical turnover markers (body weight, Hcy, vitamin B12, and folate were measured. Systolic blood pressure was measured from the right carotid artery. Tibia blood flow was measured by laser Doppler flow probe. The results indicated that Hcy levels were significantly higher in the Hcy-treated group than in control rats, whereas vitamin B12 levels were lower in the Hcy-treated group compared with control rats. There was no significant difference in folate concentration and blood pressure in Hcy-treated versus control rats. The tibial blood flow index of the control group was significantly higher (0.78 ± 0.09 flow unit compared with the Hcy-treated group (0.51 ± 0.09. The tibial mass was 1.1 ± 0.1 g in the control group and 0.9 ± 0.1 in the Hcy-treated group. The tibia bone density was unchanged in Hcy-treated rats. These results suggest that Hcy causes a reduction in bone blood flow, which contributes to compromised bone biomechanical properties.Keywords: homocysteine, tibia, bone density

  8. Chaotic advection in blood flow.

    Science.gov (United States)

    Schelin, A B; Károlyi, Gy; de Moura, A P S; Booth, N A; Grebogi, C

    2009-07-01

    In this paper we argue that the effects of irregular chaotic motion of particles transported by blood can play a major role in the development of serious circulatory diseases. Vessel wall irregularities modify the flow field, changing in a nontrivial way the transport and activation of biochemically active particles. We argue that blood particle transport is often chaotic in realistic physiological conditions. We also argue that this chaotic behavior of the flow has crucial consequences for the dynamics of important processes in the blood, such as the activation of platelets which are involved in the thrombus formation.

  9. Effect of blood flow rate on internal filtration in a high-flux dialyzer with polysulfone membrane.

    Science.gov (United States)

    Sakiyama, Ryoichi; Ishimori, Isamu; Akiba, Takashi; Mineshima, Michio

    2012-09-01

    Internal filtration/backfiltration (IF/BF) of a dialyzer depends on several parameters. This study evaluated the effect of the blood flow rate (Q (B)) on the internal filtration flow rate (Q (IF)) measured using Doppler ultrasonography for a high-flux dialyzer with a polysulfone membrane, APS-15E. In an in vitro study, bovine blood was circulated through the dialyzer, at a Q (B) of 100-350 mL/min. The clearances (CL) of creatinine, β(2)-microglobulin, and α(1)-microglobulin were then investigated. Q (IF) increased with the Q (B) value. A good correlation was obtained between Q (IF) and the pressure difference between the pressures at the inlet of the blood compartment and the pressure at the outlet of the dialysate compartment. The creatinine CL values strongly depended on Q (B) because molecular diffusion was dominant. The β(2)-microglobulin CL also depended on Q (B), because its removal rate seemed to be affected by both diffusive and convective transport caused by the IF/BF. An extremely low CL value was obtained for α(1)-microglobulin because of its low diffusivity and membrane fouling induced by proteins plugging the membrane. In conclusion, the IF/BF in the dialyzer strongly depends on Q (B). Furthermore, the dependence of the solute clearance on Q (B) decreased with increasing molecular size of the solute because of the decrease in diffusivity through the membrane.

  10. High-NaCl diet impairs dynamic renal blood flow autoregulation in rats with adenine-induced chronic renal failure.

    Science.gov (United States)

    Saeed, Aso; DiBona, Gerald F; Grimberg, Elisabeth; Nguy, Lisa; Mikkelsen, Minne Line Nedergaard; Marcussen, Niels; Guron, Gregor

    2014-03-15

    This study examined the effects of 2 wk of high-NaCl diet on kidney function and dynamic renal blood flow autoregulation (RBFA) in rats with adenine-induced chronic renal failure (ACRF). Male Sprague-Dawley rats received either chow containing adenine or were pair-fed an identical diet without adenine (controls). After 10 wk, rats were randomized to either remain on the same diet (0.6% NaCl) or to be switched to high 4% NaCl chow. Two weeks after randomization, renal clearance experiments were performed under isoflurane anesthesia and dynamic RBFA, baroreflex sensitivity (BRS), systolic arterial pressure variability (SAPV), and heart rate variability were assessed by spectral analytical techniques. Rats with ACRF showed marked reductions in glomerular filtration rate and renal blood flow (RBF), whereas mean arterial pressure and SAPV were significantly elevated. In addition, spontaneous BRS was reduced by ∼50% in ACRF animals. High-NaCl diet significantly increased transfer function fractional gain values between arterial pressure and RBF in the frequency range of the myogenic response (0.06-0.09 Hz) only in ACRF animals (0.3 ± 4.0 vs. -4.4 ± 3.8 dB; P renal failure by facilitating pressure transmission to the microvasculature.

  11. Hypertension (High Blood Pressure)

    Science.gov (United States)

    ... Loss Surgery? A Week of Healthy Breakfasts Shyness Hypertension (High Blood Pressure) KidsHealth > For Teens > Hypertension (High Blood Pressure) A ... rest temperature diet emotions posture medicines Why Is High Blood Pressure Bad? High blood pressure means a person's heart ...

  12. Treating High Blood Pressure

    Science.gov (United States)

    About High Blood Pressure Many people in the United States die from high blood pressure. This condition usually does not cause symptoms. Most ... until it is too late. A person has high blood pressure when the blood pushes against Visit your doctor ...

  13. Hyperglycemia (High Blood Glucose)

    Medline Plus

    Full Text Available ... Hyperglycemia (High Blood Glucose) Hyperglycemia is the technical term for high blood glucose (blood sugar). High blood glucose happens when the body has too little insulin or when the body can't use insulin properly. What Causes Hyperglycemia? A number of things can cause hyperglycemia: ...

  14. Hyperglycemia (High Blood Glucose)

    Medline Plus

    Full Text Available ... Blood Pressure Physical Activity High Blood Glucose My Health Advisor Tools To Know Your Risk Alert Day ... DKA (Ketoacidosis) & Ketones Kidney Disease (Nephropathy) Gastroparesis Mental Health Step On Up Treatment & Care Blood Glucose Testing ...

  15. Hyperglycemia (High Blood Glucose)

    Medline Plus

    Full Text Available ... Blood Pressure Physical Activity High Blood Glucose My Health Advisor Tools To Know Your Risk Alert Day ... DKA (Ketoacidosis) & Ketones Kidney Disease (Nephropathy) Gastroparesis Mental Health Step On Up Treatment & Care Blood Glucose Testing ...

  16. 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.

  17. Effect of high-frequency oscillation on blood flow to an atelectatic lung in closed-chest dogs.

    Science.gov (United States)

    Hall, S M; Strawn, W B; Levitzky, M G

    1984-05-01

    Seven dogs with electromagnetic flow probes implanted on their main (QT) and left (QL) pulmonary arteries, had catheters placed in their left atria and pulmonary artery, and were ventilated via Carlen's double-lumen endotracheal tubes. The effect of high-frequency oscillation (HFO) on the redistribution of pulmonary blood flow away from unilaterally atelectatic lungs was determined. During bilateral ventilation with 100% O2, using either a Harvard respirator (PPV) or an Emerson airway vibrator (HFO), the fraction of cardiac output perfusing the left lung (QL/QT) was 0.45 +/- .01 and 0.43 +/- .01, respectively, whereas PaO2 was 465 +/- 40 and 334 +/- 34 torr, respectively. With left lung atelectasis during right lung ventilation with PPV at 10 to 15 cycle/min, QL/QT fell to 0.37 +/- .01 and PaO2 was 56 +/- 5 torr. During HFO at 100 cycle/min, QL/QT fell to 0.32 +/- .02 whereas PaO2 rose to 102 +/- 23 torr. Mean transpulmonary pressure was 10.0 +/- 1.5 torr with PPV and 7.3 +/- 1.2 torr during HFO; intrapleural pressures were -3.2 +/- 1.6 and -5.7 +/- 1.4 mm Hg, respectively. Thus, the diversion of blood away from unilaterally atelectatic lungs was better maintained during HFO.

  18. Using the developed cross-flow filtration chip for collecting blood plasma under high flow rate condition and applying the immunoglobulin E detection

    Science.gov (United States)

    Yeh, Chia-Hsien; Hung, Chia-Wei; Wu, Chun-Han; Lin, Yu-Cheng

    2014-09-01

    This paper presents a cross-flow filtration chip for separating blood cells (white blood cells, red blood cells, and platelets) and obtaining blood plasma from human blood. Our strategy is to flow the sample solution in parallel to the membrane, which can generate a parallel shear stress to remove the clogging microparticles on the membrane, so the pure sample solution is obtained in the reservoir. The cross-flow filtration chip includes a cross-flow layer, a Ni-Pd alloy micro-porous membrane, and a reservoir layer. The three layers are packaged in a polymethylmethacrylate (PMMA) frame to create the cross-flow filtration chip. Various dilutions of the blood sample (original, 2 × , 3 × , 5 × , and 10×), pore sizes with different diameters (1 µm, 2 µm, 4 µm, 7 µm, and 10 µm), and different flow rates (1 mL/min, 3 mL/min, 5 mL/min, 7 mL/min, and 10 mL/min) are tested to determine their effects on filtration percentage. The best filtration percentage is 96.2% when the dilution of the blood sample is 10 × , the diameter of pore size of a Ni-Pd alloy micro-porous membrane is 2 µm, and the flow rate is 10 mL/min. Finally, for the clinical tests of the immunoglobulin E (IgE) concentration, the cross-flow filtration chip is used to filter the blood of the allergy patients to obtain the blood plasma. This filtered blood plasma is compared with that obtained using the conventional centrifugation based on the enzyme-linked immunosorbent assay. The results reveal that these two blood separation methods have similar detection trends. The proposed filtration chip has the advantages of low cost, short filtration time, and easy operation and thus can be applied to the separation of microparticles, cells, bacteria, and blood.

  19. Hyperglycemia (High Blood Glucose)

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    Full Text Available ... Your Risk Healthy Eating Overweight Smoking High Blood Pressure Physical Activity High Blood Glucose My Health Advisor ... Islanders American Indian/Alaska Native Programs Older Adults Family Link Diabetes EXPO Upcoming Diabetes EXPOs EXPO Volunteer ...

  20. Hyperglycemia (High Blood Glucose)

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    Full Text Available ... Test Lower Your Risk Healthy Eating Overweight Smoking High Blood Pressure Physical Activity High Blood Glucose My Health Advisor Tools To Know Your Risk Alert Day Diabetes Basics Home Symptoms Diagnosis America's Diabetes Challenge Type ...

  1. Hyperglycemia (High Blood Glucose)

    Medline Plus

    Full Text Available ... Test Lower Your Risk Healthy Eating Overweight Smoking High Blood Pressure Physical Activity High Blood Glucose My Health Advisor ... Index Low-Calorie Sweeteners Sugar and Desserts Fitness Exercise & Type 1 Diabetes Get Started Safely Get And ...

  2. Hyperglycemia (High Blood Glucose)

    Medline Plus

    Full Text Available ... Risk Healthy Eating Overweight Smoking High Blood Pressure Physical Activity High Blood Glucose My Health Advisor Tools To ... Complications Neuropathy Foot Complications DKA (Ketoacidosis) & Ketones Kidney Disease (Nephropathy) Gastroparesis Mental Health Step On Up Treatment & ...

  3. High blood pressure medications

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/007484.htm High blood pressure medicines To use the sharing features on this page, please enable JavaScript. Treating high blood pressure will help prevent problems such as heart disease, ...

  4. Hyperglycemia (High Blood Glucose)

    Medline Plus

    Full Text Available ... Your Risk Healthy Eating Overweight Smoking High Blood Pressure Physical Activity High Blood Glucose My Health Advisor ... Options for the Uninsured Medicare Medicaid & CHIP For Parents & Kids Safe at School Everyday Life Children and ...

  5. Hyperglycemia (High Blood Glucose)

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    Full Text Available ... Risk Test Lower Your Risk Healthy Eating Overweight Smoking High Blood Pressure Physical Activity High Blood Glucose ... Clinical Practice Guidelines Patient Education Materials Scientific Sessions Journals for Professionals Professional Books Patient Access to Research ...

  6. Hyperglycemia (High Blood Glucose)

    Medline Plus

    Full Text Available ... Risk Healthy Eating Overweight Smoking High Blood Pressure Physical Activity High Blood Glucose My Health Advisor Tools To ... Index Low-Calorie Sweeteners Sugar and Desserts Fitness Exercise & Type 1 Diabetes Get Started Safely Get And ...

  7. High blood cholesterol levels

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/000403.htm High blood cholesterol levels To use the sharing features ... stroke, and other problems. The medical term for high blood cholesterol is lipid disorder, hyperlipidemia, or hypercholesterolemia. ...

  8. Cerebral blood flow in the neonate.

    Science.gov (United States)

    Vutskits, Laszlo

    2014-01-01

    Ensuring adequate oxygenation of the developing brain is the cornerstone of neonatal critical care. Despite decades of clinical research dedicated to this issue of paramount importance, our knowledge and understanding regarding the physiology and pathophysiology of neonatal cerebral blood flow are still rudimentary. This review primarily focuses on currently available human clinical and experimental data on cerebral blood flow and autoregulation in the preterm and term infant. Limitations of systemic blood pressure values as surrogates for monitoring adequate cerebral oxygen delivery are discussed. Particular emphasis is placed on the high interindividual variability in cerebral blood flow values, vasoreactivity, and autoregulatory thresholds making the applications of normative values highly questionable. Technical and ethical difficulties to conduct such trials leave us with a near complete lack of knowledge on how pharmacological and surgical interventions impact on cerebral autoregulation. The ensemble of these works argues for the necessity of highly individualized care by taking advantage of continuous bedside monitoring of cerebral circulation. They also point to the urgent need for further studies addressing the exciting but difficult issue of cerebral blood flow autoregulation in the neonate.

  9. Ocular Blood Flow Autoregulation Mechanisms and Methods

    Directory of Open Access Journals (Sweden)

    Xue Luo

    2015-01-01

    Full Text Available The main function of ocular blood flow is to supply sufficient oxygen and nutrients to the eye. Local blood vessels resistance regulates overall blood distribution to the eye and can vary rapidly over time depending on ocular need. Under normal conditions, the relation between blood flow and perfusion pressure in the eye is autoregulated. Basically, autoregulation is a capacity to maintain a relatively constant level of blood flow in the presence of changes in ocular perfusion pressure and varied metabolic demand. In addition, ocular blood flow dysregulation has been demonstrated as an independent risk factor to many ocular diseases. For instance, ocular perfusion pressure plays key role in the progression of retinopathy such as glaucoma and diabetic retinopathy. In this review, different direct and indirect techniques to measure ocular blood flow and the effect of myogenic and neurogenic mechanisms on ocular blood flow are discussed. Moreover, ocular blood flow regulation in ocular disease will be described.

  10. Hyperglycemia (High Blood Glucose)

    Medline Plus

    Full Text Available ... an Employer Options for the Uninsured Medicare Medicaid & CHIP For Parents & Kids Safe at School Everyday Life ... blood sugar). High blood glucose happens when the body has too little insulin or when the body ...

  11. Ocular Blood Flow Autoregulation Mechanisms and Methods

    OpenAIRE

    Xue Luo; Yu-meng Shen; Meng-nan Jiang; Xiang-feng Lou; Yin Shen

    2015-01-01

    The main function of ocular blood flow is to supply sufficient oxygen and nutrients to the eye. Local blood vessels resistance regulates overall blood distribution to the eye and can vary rapidly over time depending on ocular need. Under normal conditions, the relation between blood flow and perfusion pressure in the eye is autoregulated. Basically, autoregulation is a capacity to maintain a relatively constant level of blood flow in the presence of changes in ocular perfusion pressure and va...

  12. Blood flow characteristics in the aortic arch

    Science.gov (United States)

    Prahl Wittberg, Lisa; van Wyk, Stevin; Mihaiescu, Mihai; Fuchs, Laszlo; Gutmark, Ephraim; Backeljauw, Philippe; Gutmark-Little, Iris

    2012-11-01

    The purpose with this study is to investigate the flow characteristics of blood in the aortic arch. Cardiovascular diseases are associated with specific locations in the arterial tree. Considering atherogenesis, it is claimed that the Wall Shear Stress (WSS) along with its temporal and spatial gradients play an important role in the development of the disease. The WSS is determined by the local flow characteristics, that in turn depends on the geometry as well as the rheological properties of blood. In this numerical work, the time dependent fluid flow during the entire cardiac cycle is fully resolved. The Quemada model is applied to account for the non-Newtonian properties of blood, an empirical model valid for different Red Blood Cell loading. Data obtained through Cardiac Magnetic Resonance Imaging have been used in order to reconstruct geometries of the the aortic arch. Here, three different geometries are studied out of which two display malformations that can be found in patients having the genetic disorder Turner's syndrome. The simulations show a highly complex flow with regions of secondary flow that is enhanced for the diseased aortas. The financial support from the Swedish Research Council (VR) and the Sweden-America Foundation is gratefully acknowledged.

  13. High blood pressure - infants

    Science.gov (United States)

    ... Certain tumors Inherited conditions (problems that run in families) Thyroid problems Blood pressure rises as the baby grows. The average blood ... vomiting constantly Prevention Some causes of high blood pressure run in families. Talk to your provider before you get pregnant ...

  14. High Blood Pressure Facts

    Science.gov (United States)

    ... More black women than men have high blood pressure. 2 Race of Ethnic Group Men (%) Women (%) African Americans 43.0 45.7 Mexican Americans 27.8 28.9 Whites 33.9 31.3 All 34.1 32.7 Top of Page Why Blood Pressure Matters View this graphic snapshot of blood pressure ...

  15. Hyperglycemia (High Blood Glucose)

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    Full Text Available ... Eating Overweight Smoking High Blood Pressure Physical Activity High Blood Glucose My Health Advisor Tools To Know Your Risk Alert Day Diabetes Basics Home Symptoms Diagnosis America's Diabetes Challenge Type 1 Type 2 Facts About Type 2 Enroll in ...

  16. Postexercise blood flow restriction does not enhance muscle hypertrophy induced by multiple-set high-load resistance exercise.

    Science.gov (United States)

    Madarame, Haruhiko; Nakada, Satoshi; Ohta, Takahisa; Ishii, Naokata

    2017-04-27

    To test the applicability of postexercise blood flow restriction (PEBFR) in practical training programmes, we investigated whether PEBFR enhances muscle hypertrophy induced by multiple-set high-load resistance exercise (RE). Seven men completed an eight-week RE programme for knee extensor muscles. Employing a within-subject design, one leg was subjected to RE + PEBFR, whereas contralateral leg to RE only. On each exercise session, participants performed three sets of unilateral knee extension exercise at approximately 70% of their one-repetition maximum for RE leg first, and then performed three sets for RE + PEBFR leg. Immediately after completion of the third set, the proximal portion of the RE + PEBFR leg was compressed with an air-pressure cuff for 5 min at a pressure ranging from 100 to 150 mmHg. If participants could perform 10 repetitions for three sets in two consecutive exercise sessions, the work load was increased by 5% at the next exercise session. Muscle thickness and strength of knee extensor muscles were measured before and after the eight-week training period and after the subsequent eight-week detraining period. There was a main effect of time but no condition × time interaction or main effect of condition for muscle thickness and strength. Both muscle thickness and strength increased after the training period independent of the condition. This result suggests that PEBFR would not be an effective training method at least in an early phase of adaptation to high-load resistance exercise. © 2017 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd.

  17. Hyperglycemia (High Blood Glucose)

    Medline Plus

    Full Text Available ... 2 Diabetes Risk Test Lower Your Risk Healthy Eating Overweight Smoking High Blood Pressure Physical Activity High ... What Can I Drink? Fruit Dairy Food Tips Eating Out Quick Meal Ideas Snacks Nutrient Content Claims ...

  18. TIPS bilateral noise reduction in 4D CT perfusion scans produces high-quality cerebral blood flow maps

    Energy Technology Data Exchange (ETDEWEB)

    Mendrik, Adrienne M; Van Ginneken, Bram; Viergever, Max A [Image Sciences Institute, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht (Netherlands); Vonken, Evert-jan; De Jong, Hugo W; Riordan, Alan; Van Seeters, Tom; Smit, Ewoud J; Prokop, Mathias, E-mail: a.m.mendrik@gmail.com [Radiology Department, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht (Netherlands)

    2011-07-07

    Cerebral computed tomography perfusion (CTP) scans are acquired to detect areas of abnormal perfusion in patients with cerebrovascular diseases. These 4D CTP scans consist of multiple sequential 3D CT scans over time. Therefore, to reduce radiation exposure to the patient, the amount of x-ray radiation that can be used per sequential scan is limited, which results in a high level of noise. To detect areas of abnormal perfusion, perfusion parameters are derived from the CTP data, such as the cerebral blood flow (CBF). Algorithms to determine perfusion parameters, especially singular value decomposition, are very sensitive to noise. Therefore, noise reduction is an important preprocessing step for CTP analysis. In this paper, we propose a time-intensity profile similarity (TIPS) bilateral filter to reduce noise in 4D CTP scans, while preserving the time-intensity profiles (fourth dimension) that are essential for determining the perfusion parameters. The proposed TIPS bilateral filter is compared to standard Gaussian filtering, and 4D and 3D (applied separately to each sequential scan) bilateral filtering on both phantom and patient data. Results on the phantom data show that the TIPS bilateral filter is best able to approach the ground truth (noise-free phantom), compared to the other filtering methods (lowest root mean square error). An observer study is performed using CBF maps derived from fifteen CTP scans of acute stroke patients filtered with standard Gaussian, 3D, 4D and TIPS bilateral filtering. These CBF maps were blindly presented to two observers that indicated which map they preferred for (1) gray/white matter differentiation, (2) detectability of infarcted area and (3) overall image quality. Based on these results, the TIPS bilateral filter ranked best and its CBF maps were scored to have the best overall image quality in 100% of the cases by both observers. Furthermore, quantitative CBF and cerebral blood volume values in both the phantom and the

  19. TIPS bilateral noise reduction in 4D CT perfusion scans produces high-quality cerebral blood flow maps

    Science.gov (United States)

    Mendrik, Adriënne M.; Vonken, Evert-jan; van Ginneken, Bram; de Jong, Hugo W.; Riordan, Alan; van Seeters, Tom; Smit, Ewoud J.; Viergever, Max A.; Prokop, Mathias

    2011-07-01

    Cerebral computed tomography perfusion (CTP) scans are acquired to detect areas of abnormal perfusion in patients with cerebrovascular diseases. These 4D CTP scans consist of multiple sequential 3D CT scans over time. Therefore, to reduce radiation exposure to the patient, the amount of x-ray radiation that can be used per sequential scan is limited, which results in a high level of noise. To detect areas of abnormal perfusion, perfusion parameters are derived from the CTP data, such as the cerebral blood flow (CBF). Algorithms to determine perfusion parameters, especially singular value decomposition, are very sensitive to noise. Therefore, noise reduction is an important preprocessing step for CTP analysis. In this paper, we propose a time-intensity profile similarity (TIPS) bilateral filter to reduce noise in 4D CTP scans, while preserving the time-intensity profiles (fourth dimension) that are essential for determining the perfusion parameters. The proposed TIPS bilateral filter is compared to standard Gaussian filtering, and 4D and 3D (applied separately to each sequential scan) bilateral filtering on both phantom and patient data. Results on the phantom data show that the TIPS bilateral filter is best able to approach the ground truth (noise-free phantom), compared to the other filtering methods (lowest root mean square error). An observer study is performed using CBF maps derived from fifteen CTP scans of acute stroke patients filtered with standard Gaussian, 3D, 4D and TIPS bilateral filtering. These CBF maps were blindly presented to two observers that indicated which map they preferred for (1) gray/white matter differentiation, (2) detectability of infarcted area and (3) overall image quality. Based on these results, the TIPS bilateral filter ranked best and its CBF maps were scored to have the best overall image quality in 100% of the cases by both observers. Furthermore, quantitative CBF and cerebral blood volume values in both the phantom and the

  20. Preventing High Blood Pressure

    Science.gov (United States)

    ... Web Sites Division for Heart Disease and Stroke Prevention Stroke Heart Disease Cholesterol Salt Million Hearts® WISEWOMAN Preventing High Blood Pressure: Healthy Living Habits Recommend on Facebook Tweet Share Compartir By living a healthy lifestyle, you can help keep your blood pressure in ...

  1. High blood pressure - children

    Science.gov (United States)

    ... number is the diastolic pressure. This measures the pressure in the arteries when the heart is at rest. Blood pressure ... Medical Professional Call your child's provider if home monitoring shows that your child's blood pressure is still high. Prevention Your child's provider will ...

  2. Quantitative Cerebral Blood Flow Measurements Using MRI

    OpenAIRE

    Muir, Eric R; Watts, Lora Talley; Tiwari, Yash Vardhan; Bresnen, Andrew; Timothy Q Duong

    2014-01-01

    Magnetic resonance imaging utilized as a quantitative and noninvasive method to image cerebral blood flow. The two most common techniques used to detect cerebral blood flow are dynamic susceptibility contrast (DSC) perfusion MRI and arterial spin labeling perfusion MRI. Herein we describe the use of these two techniques to measure cerebral blood flow in rodents, including methods, analysis, and important considerations when utilizing these techniques.

  3. Multiscale modeling of blood flow: from single cells to blood rheology.

    Science.gov (United States)

    Fedosov, Dmitry A; Noguchi, Hiroshi; Gompper, Gerhard

    2014-04-01

    Mesoscale simulations of blood flow, where the red blood cells are described as deformable closed shells with a membrane characterized by bending rigidity and stretching elasticity, have made much progress in recent years to predict the flow behavior of blood cells and other components in various flows. To numerically investigate blood flow and blood-related processes in complex geometries, a highly efficient simulation technique for the plasma and solutes is essential. In this review, we focus on the behavior of single and several cells in shear and microcapillary flows, the shear-thinning behavior of blood and its relation to the blood cell structure and interactions, margination of white blood cells and platelets, and modeling hematologic diseases and disorders. Comparisons of the simulation predictions with existing experimental results are made whenever possible, and generally very satisfactory agreement is obtained.

  4. Regional cerebral blood flow in schizophrenia

    Energy Technology Data Exchange (ETDEWEB)

    Mathew, R.J.; Duncan, G.C.; Weinman, M.L.; Barr, D.L.

    1982-10-01

    Regional cerebral blood flow (rCBF) was measured via xenon133 inhalation technique in 23 patients with schizophrenia and 18 age- and sex-matched controls. The mean blood flow to both hemispheres was found to be lower for the patients. The patients and their controls did not differ on interhemispheric differences in blood flow. There were no differences in rCBF between medicated and unmedicated, subchronic and chronic, and paranoid and nonparanoid patients. Hallucinations were associated with reduced blood flow to several postcentral regions.

  5. Nocturnal variations in peripheral blood flow, systemic blood pressure, and heart rate in humans

    DEFF Research Database (Denmark)

    Sindrup, J H; Kastrup, J; Christensen, H

    1991-01-01

    was associated with a 30-40% increase in blood flow rate and a highly significant decrease in mean arterial blood pressure and heart rate (P less than 0.001 for all). Approximately 100 min after the subjects went to sleep an additional blood flow rate increment (mean 56%) and a simultaneous significant decrease......Subcutaneous adipose tissue blood flow rate, together with systemic arterial blood pressure and heart rate under ambulatory conditions, was measured in the lower legs of 15 normal human subjects for 12-20 h. The 133Xe-washout technique, portable CdTe(Cl) detectors, and a portable data storage unit...... were used for measurement of blood flow rates. An automatic portable blood pressure recorder and processor unit was used for measurement of systolic blood pressure, diastolic blood pressure, and heart rate every 15 min. The change from upright to supine position at the beginning of the night period...

  6. Gastric mucosal electrical potential difference and blood flow during high FFA/albumin ratios in anaesthetized Göttingen mini-pigs

    DEFF Research Database (Denmark)

    Højgaard, L; Bülow, J B; Madsen, J;

    1988-01-01

    . The gastric blood flow was measured with the radioactive microsphere technique: at basal conditions, during high FFA/albumin ratios, and after normalization of the plasma lipids. The antrum p.d., expressed with gastric lumen negative, decreased during the increased FFA/albumin ratios; from -25 +/- 3 mV to -17......The gastric blood flow and the gastric mucosal potential difference (p.d.) was studied in anaesthetized Göttingen mini-pigs under normal conditions and during increased FFA/albumin ratios. The antrum mucosal p.d. was measured continuously with a newly developed intragastric microelectrode principle...... +/- 4 mV, (P less than 0.05). A further reduction to -12 +/- 3 mV (P less than 0.05) was observed during the normalization of the FFA/albumin ratios. The antrum and corpus mucosal blood flow values were reduced by 37 and 26% during the increased FFA/albumin ratios, and the gastric mucosal blood flow...

  7. Hyperglycemia (High Blood Glucose)

    Medline Plus

    Full Text Available ... to Give Close Are You at Risk? Home Prevention Diagnosing Diabetes and Learning About Prediabetes Type 2 Diabetes Risk Test Lower Your Risk Healthy Eating Overweight Smoking High Blood Pressure Physical Activity ...

  8. High Blood Pressure (Hypertension)

    Science.gov (United States)

    ... already been diagnosed with high blood pressure. Try yoga and meditation. Yoga and meditation not only can strengthen your body ... Accessed Sept. 21, 2015. Hu B, et al. Effects of psychological stress on hypertension in middle-aged ...

  9. Prevention of High Blood Pressure

    Science.gov (United States)

    ... page from the NHLBI on Twitter. Prevention of High Blood Pressure Healthy lifestyle habits, proper use of medicines, and ... prevent high blood pressure or its complications. Preventing High Blood Pressure Onset Healthy lifestyle habits can help prevent high ...

  10. Nutrition Coupled with High-Load Traditional or Low-Load Blood Flow Restricted Exercise During Human Limb Suspension

    Science.gov (United States)

    Hackney, K. J.; Everett, M.; Ploutz-Snyder, L. L.

    2011-01-01

    High-load resistance exercise (HRE) and low-load blood flow restricted (BFR) exercise have demonstrated efficacy for attenuating unloading related muscle atrophy and dysfunction. In recreational exercisers, protein consumption immediately before and/or after exercise has been shown to increase the skeletal muscle anabolic response to resistance training. PURPOSE: To compare the skeletal muscle adaptations when chocolate milk intake was coupled with HRE or low-load BFR exercise [3 d/wk] during simulated lower limb weightlessness. METHODS: Eleven subjects were counterbalanced [based on age and gender] to HRE (31 +/- 14 yr, 170 +/- 13 cm, 71 +/- 18 kg, 2M/3W) or low-load BFR exercise (31 +/- 12 yr, 169 +/- 13 cm, 66 +/- 14 kg, 2M/4W) during 30 days of unilateral lower limb suspension (ULLS). Both HRE and BFR completed 3 sets of single leg press and calf raise exercise during ULLS. BFR exercise intensity was 20% of repetition maximum (1RM) with a cuff inflation pressure of 1.3 systolic blood pressure (143 4 mmHg). Cuff pressure was maintained during all 3 sets including rest intervals (90s). HRE intensity was 75% 1RM and was performed without cuff inflation. Immediately (chocolate milk (150 kcal, 2.5g total fat, 22g total carbohydrate, 8g protein) was consumed to optimize acute exercise responses in favor of muscle anabolism. ULLS analog compliance was assessed from leg skin temperature recordings and plantar accelerometry. Muscle cross-sectional area (CSA) for knee extensor and plantar flexor muscle groups were determined from analysis of magnetic resonance images using ImageJ software. 1RM strength for leg press and calf raise was assessed on the Agaton exercise system. Muscular endurance during leg press and calf raise was evaluated from the maximal number of repetitions performed to volitional fatigue using 40% of pre-ULLS 1RM. RESULTS: Steps detected by plantar acceleometry declined by 98.9% during ULLS relative to an ambulatory control period. Average skin

  11. Relation of high cytomegalovirus antibody titres to blood pressure and brachial artery flow-mediated dilation in young men: the Cardiovascular Risk in Young Finns Study.

    Science.gov (United States)

    Haarala, A; Kähönen, M; Lehtimäki, T; Aittoniemi, J; Jylhävä, J; Hutri-Kähönen, N; Taittonen, L; Laitinen, T; Juonala, M; Viikari, J; Raitakari, O T; Hurme, M

    2012-02-01

    Human cytomegalovirus (CMV) infection is associated with a higher risk of cardiovascular disease in immunocompromised organ transplant patients. It has been linked with the pathogenesis of elevated arterial blood pressure. However, controversy exists as to whether CMV infection is associated with endothelial function, and little is known about its role as a potential risk factor for early atherosclerosis development at a young age. We aimed to discover if CMV antibody titres are associated with early vascular changes (carotid intima-media thickness, carotid artery distensibility and brachial artery flow-mediated dilation), blood pressure elevation or other traditional cardiovascular risk factors. CMV antibody titres were measured in 1074 women and 857 men (aged 24-39 years) taking part in the Cardiovascular Risk in Young Finns study. CMV antibody titres were significantly higher in women compared to men. In men, high CMV antibody titres were associated directly with age (P blood pressure elevation, and associated inversely with flow-mediated dilation (P = 0·014). In women, CMV antibody titres did not associate with any of the analysed parameters. In a multivariate regression model, which included traditional atherosclerotic risk factors, CMV antibody titres were independent determinants for systolic (P = 0·029) and diastolic (P = 0·004) blood pressure elevation and flow-mediated dilation (P = 0·014) in men. High CMV antibody titres are associated independently with blood pressure and brachial artery flow-mediated dilation in young men. This association supports the hypothesis that common CMV infection and/or an immune response to CMV may lead to impaired vascular function at a young age. © 2012 The Authors. Clinical and Experimental Immunology © 2012 British Society for Immunology.

  12. High Blood Pressure Fact Sheet

    Science.gov (United States)

    ... High Blood Pressure Salt Cholesterol Million Hearts® WISEWOMAN High Blood Pressure Fact Sheet Language: English Español (Spanish) Recommend on ... time. High blood pressure is also called hypertension. High Blood Pressure in the United States Having high blood pressure ...

  13. Ciliary Blood Flow and Aqueous Humor Production

    Science.gov (United States)

    Kiel, J.W.; Hollingsworth, M.; Rao, R.; Chen, M.; Reitsamer, H.A.

    2010-01-01

    Aqueous humor production is a metabolically active process sustained by the delivery of oxygen and nutrients and removal of metabolic waste by the ciliary circulation. This article describes our investigations into the relationship between ciliary blood flow and aqueous humor production. The results presented indicate that there is a dynamic relationship between ciliary blood flow and aqueous humor production, with production being blood flow independent above a critical level of perfusion, and blood flow dependent below it. The results also show that the plateau portion of the relationship shifts up or down depending on the level of secretory stimulation or inhibition, and that oxygen is one critical factor provided by ciliary blood flow. Also presented is a theoretical model of ocular hydrodynamics incorporating these new findings. PMID:20801226

  14. Micro-PIV measurements of blood flow in extraembryonic blood vessels of chicken embryos.

    Science.gov (United States)

    Lee, Jung Yeop; Ji, Ho Seong; Lee, Sang Joon

    2007-10-01

    The hemodynamic characteristics of blood flow are important in the diagnosis of circulatory diseases, since such diseases are related to wall shear stress of cardiovascular vessels. In chicken embryos at early stages of development, it is possible to directly visualize blood flow inside blood vessels. We therefore employed a micro-PIV technique to assess blood flow in extraembryonic venous and arterial blood vessels of chicken embryos, using red blood cells (RBCs) as tracers and obtaining flow images of RBCs using a high-speed CMOS camera. The mean velocity field showed non-Newtonian flow characteristics. The blood flow in two venous vessels merged smoothly into the Y-shaped downstream vein without any flow separation or secondary flow. Vorticity was high in the inner regions, where the radius of curvature varied greatly. A periodic variation of temporally resolved velocity signals, due to beating of the heart, was observed in arterial blood vessels. The pulsating frequency was obtained by fast Fourier transform analysis using the measured velocity data. The measurement technique used here was useful in analyzing the hemodynamic characteristics of in vivo blood flow in chicken embryos.

  15. Hyperglycemia (High Blood Glucose)

    Medline Plus

    Full Text Available ... Type 2 Diabetes Risk Test Lower Your Risk Healthy Eating Overweight Smoking High Blood Pressure Physical Activity High ... Holiday Meal Planning What Can I Eat? Making Healthy Food Choices Diabetes ... Tips Eating Out Quick Meal Ideas Snacks Nutrient Content Claims ...

  16. Mechanics of blood flow in the microcirculation.

    Science.gov (United States)

    Secomb, T W

    1995-01-01

    The microcirculation in most tissues consists of an intricate network of very narrow tubes. In analyses of blood flow through the microcirculation, inertial effects can be neglected, but continuum models for blood cannot be assumed, since blood is a concentrated suspension of cells with dimensions comparable to vessel diameters. These cells strongly influence blood flow. About 45% of blood volume consists of red blood cells, whose key mechanical properties are known. A red cell has a fluid interior, surrounded by a flexible membrane, which strongly resists area changes, but bends and shears easily. White blood cells are comparable in size but much less numerous. They are less flexible than red cells and capable of active locomotion. Other suspended elements are much smaller than red cells: This review focuses on the mechanics of red cell motion in the microcirculation. Experimental and theoretical studies of blood flow in uniform tubes, bifurcations and networks are discussed. Comparisons between predicted and observed flows in networks imply that resistance to blood flow in living microvessels is higher than that in uniform tubes with corresponding diameters. Living microvessels have non-uniform geometries, and red cells must deform continually to traverse them. Theoretical results are presented implying that these transient deformations contribute to increased flow resistance in the microcirculation.

  17. Diagnosis of High Blood Pressure

    Medline Plus

    Full Text Available ... the NHLBI on Twitter. Diagnosis of High Blood Pressure For most patients, health care providers diagnose high ... 140/90 mmHg or above. Confirming High Blood Pressure A blood pressure test is easy and painless ...

  18. Blood flow autoregulation in pedicled flaps

    DEFF Research Database (Denmark)

    Bonde, Christian T; Holstein-Rathlou, Niels-Henrik; Elberg, Jens J

    2009-01-01

    INTRODUCTION: Clinical work on the blood perfusion in skin and muscle flaps has suggested that some degree of blood flow autoregulation exists in such flaps. An autoregulatory mechanism would enable the flap to protect itself from changes in the perfusion pressure. The purpose of the present study...... was to evaluate if, and to what extent, a tissue flap could compensate a reduction in blood flow due to an acute constriction of the feed artery. Further, we wanted to examine the possible role of smooth muscle L-type calcium channels in the autoregulatory mechanism by pharmacological intervention with the L......-type calcium channel blocker nimodipine and the vasodilator papaverine. MATERIAL AND METHODS: Pedicled flaps were raised in pigs. Flow in the pedicle was reduced by constriction of the feed artery (n=34). A transit time flow probe measured the effect on blood flow continuously. Following this, three different...

  19. Exploration of 4D MRI blood flow using stylistic visualization.

    Science.gov (United States)

    van Pelt, Roy; Oliván Bescós, Javier; Breeuwer, Marcel; Clough, Rachel E; Gröller, M Eduard; ter Haar Romenij, Bart; Vilanova, Anna

    2010-01-01

    Insight into the dynamics of blood-flow considerably improves the understanding of the complex cardiovascular system and its pathologies. Advances in MRI technology enable acquisition of 4D blood-flow data, providing quantitative blood-flow velocities over time. The currently typical slice-by-slice analysis requires a full mental reconstruction of the unsteady blood-flow field, which is a tedious and highly challenging task, even for skilled physicians. We endeavor to alleviate this task by means of comprehensive visualization and interaction techniques. In this paper we present a framework for pre-clinical cardiovascular research, providing tools to both interactively explore the 4D blood-flow data and depict the essential blood-flow characteristics. The framework encompasses a variety of visualization styles, comprising illustrative techniques as well as improved methods from the established field of flow visualization. Each of the incorporated styles, including exploded planar reformats, flow-direction highlights, and arrow-trails, locally captures the blood-flow dynamics and may be initiated by an interactively probed vessel cross-section. Additionally, we present the results of an evaluation with domain experts, measuring the value of each of the visualization styles and related rendering parameters.

  20. Carbon dioxide and liver blood flow.

    Science.gov (United States)

    Dutton, R; Levitzky, M; Berkman, R

    1976-01-01

    This study was designed to determine blood flow to the liver during hypercapnia and combined hypercapnia-hypoxia with the portal vein and hepatic artery intact except for placement of an electromagnetic flow probe around these vessels. Twenty mongrel dogs weighing 30-45 kg were anesthetized with pentobarbital and flow probes and occluders were surgically implanted. Ten of these dogs were subjected to hypercapnia alone. During inspiration of 6% CO2 in room air, portal vein flow increased from 588 +/- 73 ml/min to 731 +/- 113 ml/min (p less than .05), while hepatic artery flow did not change significantly from its control mean of 221 +/- 38 ml/min. In the remaining dogs, inhalation of 6% O2 resulted in a reduction of portal blood flow within 30 min from 527 +/- 55 ml/min to 381 +/- 41 ml/min (p less than .01). Again, mean hepatic artery flow did not increase significantly above its control of 273 +/- 43 ml/min. Subsequent inhalation of 6% CO2 plus 6% O2 (combined hypercapniahypoxia) for 30 min in these same animals resulted in a significant increase of portal vein blood flow from 514 +/- 46 ml/min to 716 +/- 116 ml/min (p less than .05). Thus, hypercapnia alone increases total liver blood flow, primarily by an increase in portal vein flow. Hypoxia results in a decrease in portal vein flow. The superimposition of hypercapnia on hypoxia restores blood flow to a level close to that found with hypercapnia alone. Hypercapnia in the range of 63 +/- 4 mmHg PCO2 overwhelms the tendency toward a reduction of portal vein blood flow induced by an arterial PO2 of 42 +/- 5 mmHg in the presence of mild hypocapnia (PCO2 : 30.2 +/- 1 mmHg).

  1. Hyperglycemia (High Blood Glucose)

    Medline Plus

    Full Text Available ... In Memory In Honor Become a Member En Español Type 1 Type 2 About Us Online Community ... Page Text Size: A A A Listen En Español Hyperglycemia (High Blood Glucose) Hyperglycemia is the technical ...

  2. Hypertension (High Blood Pressure)

    Science.gov (United States)

    ... over the years led to verification of the important role of high blood pressure—especially in concert with ... is specific for that person will be an important key to improving prevention, ... an international team of investigators, funded in part by the NIH, ...

  3. Cerebral blood flow tomography with xenon-133

    Energy Technology Data Exchange (ETDEWEB)

    Lassen, N.A.

    1985-10-01

    Cerebral blood flow (CBF) can be measured tomographically by inhalation of Xenon-/sup 133/. The calculation is based on taking a sequence of tomograms during the wash-in and wash-out phase of the tracer. Due to the dynamic nature of the process, a highly sensitive and fast moving single photon emission computed tomograph (SPECT) is required. Two brain-dedicated SPECT systems designed for this purpose are mentioned, and the method is described with special reference to the limitations inherent in the soft energy of the 133Xe primary photons. CBF tomography can be used for a multitude of clinical and investigative purposes. This article discusses in particular its use for the selection of patients with carotid occlusion for extracranial/intracranial bypass surgery, for detection of severe arterial spasm after aneurysm bleeding, and for detection of low flow areas during severe migraine attacks. The use of other tracers for CBF tomography using SPECT is summarized with emphasis on the /sup 99m/Tc chelates that freely pass the intact blood-brain barrier. The highly sensitive brain-dedicated SPECT systems described are a prerequisite for achieving high resolution tomograms with such tracers.

  4. Bone blood flow and metabolism in humans

    DEFF Research Database (Denmark)

    Heinonen, Ilkka; Kemppainen, Jukka; Kaskinoro, Kimmo

    2012-01-01

    in femoral bone at rest and during one leg intermittent isometric exercise with increasing exercise intensities. In nine men, blood flow in femur was determined at rest and during dynamic one leg exercise, and two other physiological perturbations: moderate systemic hypoxia (14 O(2) ) at rest and during...... leg. In conclusion, resting femoral bone blood flow increases by physical exercise, but appears to level off with increasing exercise intensities. Moreover, while moderate systemic hypoxia does not change bone blood flow at rest or during exercise, intra-arterially administered adenosine during...

  5. High Speed Blood and Transfusion Equipment

    Science.gov (United States)

    2013-10-14

    used to calculate percent hemolysis of red blood cells. Plasma Free Hemoglobin Assay - pRBCs samples were assayed for plasma free hemoglobin (PFH...resulting in high temperatures gradients that preludes blood hemolysis if fluid flow stops. • The solenoid valve has been replaced with a valve of a more...pRBCs to test efficacy. Both pre and post cartridge blood samples were evaluated to determine if any damage may have occurred to blood cells. The

  6. PERFORMANCE MODELING AND ANALYSIS OF BLOOD FLOW IN ELASTIC ARTERIES

    Institute of Scientific and Technical Information of China (English)

    Anil Kumar; C.L. Varshney; G.C. Sharma

    2005-01-01

    Two different non-Newtonian models for blood flow are considered, first a simple power law model displaying shear thinning viscosity, and second a generalized Maxwell model displaying both shear thinning viscosity and oscillating flow viscous-elasticity. These models are used along with a Newtonian model to study sinusoidal flow of blood in rigid and elastic straight arteries in the presence of magnetic field. The elasticity of blood does not appear to influence its flow behavior under physiological conditions in the large arteries,purely viscous shear thinning model should be quite realistic for simulating blood flow under these conditions. On using the power law model with high shear rate for sinusoidal flow simulation in elastic arteries, the mean and amplitude of the flow rate were found to be lower for a power law fluid compared to Newtonian fluid for the same pressure gradient. The governing equations have been solved by Crank-Niclson scheme. The results are interpreted in the context of blood in the elastic arteries keeping the magnetic effects in view. For physiological flow simulation in the aorta, an increase in mean wall shear stress, but a reduction in peak wall shear stress were observed for power law model compared to a Newtonian fluid model for matched flow rate wave form. Blood flow in the presence of transverse magnetic field in an elastic artery is investigated and the influence of factors such as morphology and surface irregularity is evaluated.

  7. What Causes High Blood Pressure?

    Science.gov (United States)

    ... page from the NHLBI on Twitter. Causes of High Blood Pressure Changes, either from genes or the environment, in ... and blood vessel structure and function. Biology and High Blood Pressure Researchers continue to study how various changes in ...

  8. High Red Blood Cell Count

    Science.gov (United States)

    Symptoms High red blood cell count By Mayo Clinic Staff A high red blood cell count is an increase in oxygen-carrying cells in your bloodstream. Red blood cells transport oxygen from your lungs to tissues throughout ...

  9. Diagnosis of High Blood Pressure

    Medline Plus

    Full Text Available ... Blood Pressure » Diagnosis of High Blood Pressure Explore High Blood Pressure What Is... Other Names Causes Who Is at Risk Signs & Symptoms Diagnosis Treatments Prevention Living With Clinical ...

  10. High-flow bypass and wrap-clipping for ruptured blood blister-like aneurysm of the internal carotid artery using intraoperative monitoring of cerebral hemodynamics

    Directory of Open Access Journals (Sweden)

    Kubo Y

    2015-06-01

    Full Text Available Yoshitaka Kubo, Takahiro Koji, Kenji Yoshida, Hideo Saito, Akira Ogawa, Kuniaki Ogasawara Department of Neurosurgery, Iwate Medical University, Morioka, Japan Abstract: Aneurysms at non-branching sites in the supraclinoid internal carotid artery (ICA can be classified as “blood blister-like aneurysms” (BBAs, which have blood blister-like configurations and fragile walls. While surgical treatment for the BBA in the acute stage is recommended, the optimal surgical procedure remains controversial. In the study reported here, we describe the case of a 37-year-old woman with a ruptured BBA in the ophthalmic segment of the right ICA who underwent wrap-clipping with external carotid artery–internal carotid artery bypass by intraoperative estimation of the measurement of cortical cerebral blood flow (CoBF using a thermal diffusion flow probe. Trapping of the ICA in the acute stage of subarachnoid hemorrhage may result in ischemic complications secondary to hemodynamic hypoperfusion or occlusion of the perforating artery, and/or delayed vasospasm, even with concomitant bypass surgery. We believe that it is important to perform scheduled external carotid artery–internal carotid artery bypass before trapping of the ICA in patients with a ruptured BBA in the acute stage of subarachnoid hemorrhage and to perform wrap-clipping rather than trapping. This would provide much more CoBF if a reduction of CoBF occurs after trapping occlusion of the ICA including a ruptured BBA according to intraoperative CoBF monitoring. As far as we are aware, the case reported here is the first report on high-flow bypass and wrap-clipping for a ruptured BBA of the ICA using intraoperative monitoring of cerebral hemodynamics. Keywords: surgery, cortical blood flow, external carotid artery–internal carotid artery bypass, subarachnoid hemorrhage

  11. Brachial blood flow under relative levels of blood flow restriction is decreased in a nonlinear fashion.

    Science.gov (United States)

    Mouser, J Grant; Ade, Carl J; Black, Christopher D; Bemben, Debra A; Bemben, Michael G

    2017-04-12

    Blood flow restriction (BFR), the application of external pressure to occlude venous return and restrict arterial inflow, has been shown to increase muscular size and strength when combined with low-load resistance exercise. BFR in the research setting uses a wide range of pressures, applying a pressure based upon an individual's systolic pressure or a percentage of occlusion pressure; not a directly determined reduction in blood flow. The relationship between relative pressure and blood flow has not been established. To measure blood flow in the arm under relative levels of BFR. Forty-five people (18-40 years old) participated. Arterial occlusion pressure in the right arm was measured using a 5-cm pneumatic cuff. Blood flow in the brachial artery was measured at rest and at pressures between 10% and 90% of occlusion using ultrasound. Blood flow decreased in a nonlinear, stepped fashion. Blood flow decreased at 10% of occlusion and remained constant until decreasing again at 40%, where it remained until 90% of occlusion. The decrease in brachial blood flow is not proportional to the applied relative pressure. The prescription of blood flow restriction should take into account the stimulus provided at each relative level of blood flow. © 2017 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd.

  12. Tissue blood flow mapping using laser technology

    Science.gov (United States)

    Wardell, Karin; Linden, Maria; Nilsson, Gert E.

    1995-03-01

    By the introduction of the laser Doppler perfusion imager (LDPI) the microvascular blood flow in a tissue area can be mapped by sequentially moving a laser beam over the tissue. The measurement is performed without touching the tissue and the captured perfusion values in the peripheral circulation are presented as a color-coded image. In the ordinary LDPI-set-up, 64 X 64 measurement sites cover an area in the range of about 10 - 150 cm2 depending on system settings. With a high resolution modification, recordings can be done on tissue areas as small as 1 cm2. This high resolution option has been assessed in animal models for the mapping of small vessels. To be able to record not only spatial but also temporal perfusion components of tissue blood flow, different local area scans (LAS) have been developed. These include single point recording as well as integration of either 2 X 2, 3 X 3, or 4 X 4 measurement sites. The laser beam is repeatedly moved in a quadratic pattern over the small tissue area of interest and the output value constitutes the average perfusion of all captured values within the actual region. For the evaluation, recordings were performed on healthy volunteers before and after application of a vasodilatating cream on the dorsal side of the hand.

  13. Regulation of blood flow by prostaglandins

    DEFF Research Database (Denmark)

    Boushel, Robert Christopher; Langberg, H; Risum, N;

    2004-01-01

    adaptation of connective tissues e.g. tendon. This review covers the role of PG for mediating tissue blood flow at rest and during increases in metabolic demand such as exercise and reactive hyperaemia. There is strong evidence that PGs contribute to elevate blood flow at rest and during reactive hyperaemia...... in a variety of tissues. Their role for regulating the large increases in muscle blood flow during exercise is less clear which may be explained by redundant mechanisms. Several interactions are known to exist between specific vasodilator substances, and therefore PGs can act in synergy with other substances...... and contribute to functional hyperaemia. Furthermore, there is evidence for differential, tissue-specific influences of PGs where their influence on blood flow during exercise may be profound....

  14. Blood flow and permeability in microvessels

    Science.gov (United States)

    Sugihara-Seki, Masako; Fu, Bingmei M.

    2005-07-01

    The mechanics of blood flow in microvessels and microvessel permeability are reviewed. In the first part, characteristics of blood flow in vivo and in vitro are described from a fluid-mechanical point of view, and mathematical models for blood flow in microvessels are presented. Possible causes of the increased flow resistance obtained in vivo compared to in vitro are examined, including the effects of irregularities of vessel lumen, the presence of endothelial surface glycocalyx and white blood cells. In the second part, the ultrastructural pathways and mechanisms whereby endothelial cells and the clefts between the cells modulate microvessel permeability to water and solutes are introduced. Previous and current models for microvessel permeability to water and solutes are reviewed. These models examine the role of structural components of interendothelial cleft, such as junction strands and surface glycocalyx, in the determination of water and solute transport across the microvessel walls. Transport models in the tissue space surrounding the microvessel are also described.

  15. Clinical relevance of intermittent tumour blood flow

    Energy Technology Data Exchange (ETDEWEB)

    Durand, Ralph E.; Aquino-Parsons, Christina [British Columbia Cancer Research Centre, Vancouver (Canada)

    2001-12-01

    One of the goals of translational cancer research is to understand basic 'phenomena' so that tumour response to therapy can be improved. One such phenomenon is intermittent tumour blood flow. The impact of the transient hypoxia that results from decreased tumour blood flow is now beginning to be appreciated in preclinical systems, and also receiving some attention in clinical practise. Thus in this article we review the nature and frequency of microregional blood flow changes in preclinical and clinical tumours and examine the impact of those changes on response to both radiotherapy and chemotherapy. Additionally, the implications of non-constant blood flow for both the growth of the unperturbed tumour and the regrowth of surviving tumour clonogens during and after therapy are examined.

  16. Frequency encoding in renal blood flow regulation

    DEFF Research Database (Denmark)

    Marsh, Donald J; Sosnovtseva, Olga; Pavlov, Alexey N;

    2005-01-01

    With a model of renal blood flow regulation, we examined consequences of tubuloglomerular feedback (TGF) coupling to the myogenic mechanism via voltage-gated Ca channels. The model reproduces the characteristic oscillations of the two mechanisms and predicts frequency and amplitude modulation...... of the myogenic oscillation by TGF. Analysis by wavelet transforms of single-nephron blood flow confirms that both amplitude and frequency of the myogenic oscillation are modulated by TGF. We developed a double-wavelet transform technique to estimate modulation frequency. Median value of the ratio of modulation...... TGF cycle to the next. We used a blood pressure signal recorded by telemetry from a conscious rat as the input to the model. Blood pressure fluctuations induced variability in the modulation records similar to those found in the nephron blood flow results. Frequency and amplitude modulation can...

  17. Living with High Blood Pressure

    Science.gov (United States)

    ... page from the NHLBI on Twitter. Living With High Blood Pressure If you have high blood pressure, the best thing to do is to talk ... help you track your blood pressure. Pregnancy Planning High blood pressure can cause problems for mother and baby. High ...

  18. Cerebral blood flow response to functional activation

    DEFF Research Database (Denmark)

    Paulson, Olaf B; Hasselbalch, Steen G; Rostrup, Egill

    2010-01-01

    Cerebral blood flow (CBF) and cerebral metabolic rate are normally coupled, that is an increase in metabolic demand will lead to an increase in flow. However, during functional activation, CBF and glucose metabolism remain coupled as they increase in proportion, whereas oxygen metabolism only...

  19. Diagnosis of High Blood Pressure

    Medline Plus

    Full Text Available ... High Blood Pressure Explore High Blood Pressure What Is... Other Names Causes Who Is at Risk Signs & Symptoms Diagnosis Treatments Prevention Living ... Confirming High Blood Pressure A blood pressure test is easy and painless and can be done in ...

  20. Diagnosis of High Blood Pressure

    Medline Plus

    Full Text Available ... providers diagnose high blood pressure when blood pressure readings are consistently 140/90 mmHg or above. Confirming ... minutes before the test. To track blood pressure readings over a period of time, the health care ...

  1. 21 CFR 870.2120 - Extravascular blood flow probe.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Extravascular blood flow probe. 870.2120 Section... blood flow probe. (a) Identification. An extravascular blood flow probe is an extravascular ultrasonic or electromagnetic probe used in conjunction with a blood flowmeter to measure blood flow in...

  2. High-resolution phase-contrast MRI of aortic and pulmonary blood flow during rest and physical exercise using a MRI compatible bicycle ergometer

    Energy Technology Data Exchange (ETDEWEB)

    Weber, Tim Frederik, E-mail: tim.weber@med.uni-heidelberg.de [Department of Diagnostic and Interventional Radiology, University Medical Center Heidelberg, INF 110, 69120 Heidelberg (Germany); Department of Radiology, German Cancer Research Center, INF 280, 69120 Heidelberg (Germany); Tengg-Kobligk, Hendrik von, E-mail: hendrik.tengg-kobligk@med.uni-heidelberg.de [Department of Diagnostic and Interventional Radiology, University Medical Center Heidelberg, INF 110, 69120 Heidelberg (Germany); Department of Radiology, German Cancer Research Center, INF 280, 69120 Heidelberg (Germany); Kopp-Schneider, Annette, E-mail: kopp@dkfz-heidelberg.de [Department of Biostatistics, German Cancer Research Center, INF 280, 69120 Heidelberg (Germany); Ley-Zaporozhan, Julia, E-mail: julia.ley-zaporozhan@med.uni-heidelberg.de [Department of Pediatric Radiology, University Medical Center Heidelberg, INF 430, 69120 Heidelberg (Germany); Kauczor, Hans-Ulrich, E-mail: hans-ulrich.kauczor@med.uni-heidelberg.de [Department of Diagnostic and Interventional Radiology, University Medical Center Heidelberg, INF 110, 69120 Heidelberg (Germany); Ley, Sebastian, E-mail: sebastian.ley@med.uni.heidelberg.de [Department of Radiology, German Cancer Research Center, INF 280, 69120 Heidelberg (Germany); Department of Pediatric Radiology, University Medical Center Heidelberg, INF 430, 69120 Heidelberg (Germany)

    2011-10-15

    Purpose: To establish high-resolution phase-contrast magnetic resonance imaging (PC-MRI) using a MRI compatible bicycle ergometer to quantify aortic and pulmonary blood flow during resting conditions and exercise. Materials and methods: In 20 healthy volunteers (mean age, 26.8 {+-} 5.0 years) high-resolution PC-MRI (mean temporal resolution, 7.4 {+-} 3.2 ms) was performed in the ascending aorta (AA) and main pulmonary artery (PA) during physical rest and three exercise stages: stage 1, no-load operation; stage 2, heart rate increase 40% compared to rest; stage 3, heart rate increase 80% compared to rest. Flow quantification in AA and PA included flow volume (FV), average velocity (AV), peak velocity (PV) and time to PV (TP). Results: In stage 1 only TP demonstrated a significant change. With progression to stage 2, all parameters altered significantly. Flow measurements during stage 3 evidenced further alterations only of AV and TP regarding both AA and PA. The deviation of the heart rate from the desired target value was significantly higher for stage 3 compared to stage 2, and 15% of the subjects did not reach the desired target heart rate of stage 3 at all. Conclusion: Flow quantification by high-resolution PC-MRI during exercise using a MRI compatible bicycle ergometer is feasible. Medium exercise stages are necessary and sufficient to demonstrate flow alterations in healthy volunteers. PC-MRI ergometry may give insights into aberrant hemodynamic conditions in patients with cardiovascular and pulmonary disease.

  3. 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....

  4. Ultrafast Ultrasound Imaging of Ocular Anatomy and Blood Flow

    Science.gov (United States)

    Urs, Raksha; Ketterling, Jeffrey A.; Silverman, Ronald H.

    2016-01-01

    Purpose Ophthalmic ultrasound imaging is currently performed with mechanically scanned single-element probes. These probes have limited capabilities overall and lack the ability to image blood flow. Linear-array systems are able to detect blood flow, but these systems exceed ophthalmic acoustic intensity safety guidelines. Our aim was to implement and evaluate a new linear-array–based technology, compound coherent plane-wave ultrasound, which offers ultrafast imaging and depiction of blood flow at safe acoustic intensity levels. Methods We compared acoustic intensity generated by a 128-element, 18-MHz linear array operated in conventionally focused and plane-wave modes and characterized signal-to-noise ratio (SNR) and lateral resolution. We developed plane-wave B-mode, real-time color-flow, and high-resolution depiction of slow flow in postprocessed data collected continuously at a rate of 20,000 frames/s. We acquired in vivo images of the posterior pole of the eye by compounding plane-wave images acquired over ±10° and produced images depicting orbital and choroidal blood flow. Results With the array operated conventionally, Doppler modes exceeded Food and Drug Administration safety guidelines, but plane-wave modalities were well within guidelines. Plane-wave data allowed generation of high-quality compound B-mode images, with SNR increasing with the number of compounded frames. Real-time color-flow Doppler readily visualized orbital blood flow. Postprocessing of continuously acquired data blocks of 1.6-second duration allowed high-resolution depiction of orbital and choroidal flow over the cardiac cycle. Conclusions Newly developed high-frequency linear arrays in combination with plane-wave techniques present opportunities for the evaluation of ocular anatomy and blood flow, as well as visualization and analysis of other transient phenomena such as vessel wall motion over the cardiac cycle and saccade-induced vitreous motion. PMID:27428169

  5. An implantable blood pressure and flow transmitter.

    Science.gov (United States)

    Rader, R. D.; Meehan, J. P.; Henriksen, J. K. C.

    1973-01-01

    A miniature totally implantable FM/FM telemetry system has been developed to simultaneously measure blood pressure and blood flow, thus providing an appreciation of the hemodynamics of the circulation to the entire body or to a particular organ. Developed for work with animal subjects, the telemetry system's transmission time is controlled by an RF signal that permits an operating life of several months. Pressure is detected by a miniature intravascular transducer and flow is detected by an extravascular interferometric ultrasonic technique. Both pressure and flow are calibrated prior to implanting. The pressure calibration can be checked after the implanting by cannulation; flow calibration can be verified only at the end of the experiment by determining the voltage output from the implanted sensing system as a function of several measured flow rates. The utility of this device has been established by its use in investigating canine renal circulation during exercise, emotional encounters, administration of drugs, and application of accelerative forces.

  6. Regulation of exercise blood flow: Role of free radicals.

    Science.gov (United States)

    Trinity, Joel D; Broxterman, Ryan M; Richardson, Russell S

    2016-09-01

    During exercise, oxygen and nutrient rich blood must be delivered to the active skeletal muscle, heart, skin, and brain through the complex and highly regulated integration of central and peripheral hemodynamic factors. Indeed, even minor alterations in blood flow to these organs have profound consequences on exercise capacity by modifying the development of fatigue. Therefore, the fine-tuning of blood flow is critical for optimal physical performance. At the level of the peripheral circulation, blood flow is regulated by a balance between the mechanisms responsible for vasodilation and vasoconstriction. Once thought of as toxic by-products of in vivo chemistry, free radicals are now recognized as important signaling molecules that exert potent vasoactive responses that are dependent upon the underlying balance between oxidation-reduction reactions or redox balance. Under normal healthy conditions with low levels of oxidative stress, free radicals promote vasodilation, which is attenuated with exogenous antioxidant administration. Conversely, with advancing age and disease where background oxidative stress is elevated, an exercise-induced increase in free radicals can further shift the redox balance to a pro-oxidant state, impairing vasodilation and attenuating blood flow. Under these conditions, exogenous antioxidants improve vasodilatory capacity and augment blood flow by restoring an "optimal" redox balance. Interestingly, while the active skeletal muscle, heart, skin, and brain all have unique functions during exercise, the mechanisms by which free radicals contribute to the regulation of blood flow is remarkably preserved across each of these varied target organs.

  7. Functional Doppler optical coherence tomography for cortical blood flow imaging

    Science.gov (United States)

    Yu, Lingfeng; Liu, Gangjun; Nguyen, Elaine; Choi, Bernard; Chen, Zhongping

    2010-02-01

    Optical methods have been widely used in basic neuroscience research to study the cerebral blood flow dynamics in order to overcome the low spatial resolution associated with magnetic resonance imaging and positron emission tomography. Although laser Doppler imaging and laser speckle imaging can map out en face cortical hemodynamics and columns, depth resolution is not available. Two-photon microscopy has been used for mapping cortical activity. However, flow measurement requires fluorescent dye injection, which can be problematic. The noninvasive and high resolution tomographic capabilities of optical coherence tomography make it a promising technique for mapping depth resolved cortical blood flow. Here, we present a functional Doppler optical coherence tomography (OCT) imaging modality for quantitative evaluation of cortical blood flow in a mouse model. Fast, repeated, Doppler OCT scans across a vessel of interest were performed to record flow dynamic information with a high temporal resolution of the cardiac cycles. Spectral Doppler analysis of continuous Doppler images demonstrates how the velocity components and longitudinally projected flow-volume-rate change over time, thereby providing complementary temporal flow information to the spatially distributed flow information of Doppler OCT. The proposed functional Doppler OCT imaging modality can be used to diagnose vessel stenosis/blockage or monitor blood flow changes due to pharmacological agents/neuronal activities. Non-invasive in-vivo mice experiments were performed to verify the capabilities of function Doppler OCT.

  8. Skeletal Blood Flow in Bone Repair and Maintenance

    Institute of Scientific and Technical Information of China (English)

    Ryan E.Tomlinson; Matthew J.Silva

    2013-01-01

    Bone is a highly vascularized tissue, although this aspect of bone is often overlooked. In this article, the importance of blood flow in bone repair and regeneration will be reviewed. First, the skeletal vascular anato-my, with an emphasis on long bones, the distinct mechanisms for vascularizing bone tissue, and methods for remodeling existing vasculature are discussed. Next, techniques for quantifying bone blood flow are briefly summarized. Finally, the body of experimental work that demonstrates the role of bone blood flow in fracture healing, distraction osteogenesis, osteoporosis, disuse osteopenia, and bone grafting is examined. These results illustrate that adequate bone blood flow is an important clinical consideration, particularly during bone regeneration and in at-risk patient groups.

  9. Niflumic Acid Attenuated Pulmonary Artery Tone and Vascular Structural Remodeling of Pulmonary Arterial Hypertension Induced by High Pulmonary Blood Flow In Vivo.

    Science.gov (United States)

    Wang, Kai; Ma, Jianfa; Pang, Yusheng; Lao, Jinquan; Pan, Xuanren; Tang, Qiaoyun; Zhang, Feng; Su, Danyan; Qin, Suyuan; Shrestha, Arnav Prasad

    2015-10-01

    Calcium-activated chloride channels (CaCCs) play a vital role in regulating pulmonary artery tone during pulmonary arterial hypertension (PAH) induced by high blood flow. The role of CaCCs inhibitor niflumic acid (NFA) in vivo during this process requires further investigation. We established the PAH model by abdominal shunt surgery and treated with NFA in vivo. Fifty rats were randomly divided into normal, sham, shunt, NFA group 1 (0.2 mg/kg), and NFA group 2 (0.4 mg/kg). Pathological changes, right ventricle hypertrophy index, arterial wall area/vessel area, and arterial wall thickness/vessel external diameter were analyzed. Then contraction reactions of pulmonary arteries were measured. Finally, the electrophysiological characteristics of pulmonary arterial smooth muscle cells were investigated using patch-clamp technology. After 11 weeks of shunting, PAH developed, accompanied with increased right ventricle hypertrophy index, arterial wall area/vessel area, and arterial wall thickness/vessel external diameter. In the NFA treatment groups, the pressure and pathological changes were alleviated. The pulmonary artery tone in the shunt group increased, whereas it decreased after NFA treatment. The current density of CaCC was higher in the shunt group, and it was decreased in the NFA treatment groups. In conclusion, NFA attenuated pulmonary artery tone and structural remodeling in PAH induced by high pulmonary blood flow in vivo. CaCCs were involved and the augmented current density was alleviated by NFA treatment.

  10. BLOOD FLOW AND MACROMOLECULAR TRANSPORT IN CURVED BLOOD VESSELS

    Institute of Scientific and Technical Information of China (English)

    WEI Lan; WEN Gong-bi; TAN Wen-chang

    2006-01-01

    A numerical analysis of the steady/pulsatile flow and macromolecular (such as LDL and Albumin) transport in curved blood vessels was carried out. The computational results predict that the vortex of the secondary flow is time-dependent in the aortic arch.The concentration of macromolecule concentrates at the region of sharp curve, and the wall concentration at the outer part is higher than that at the inner part. Atherosclerosis and thrombosis are prone to develop in such regions with sharp flow.

  11. Blood flow changes coincide with cellular rearrangements during blood vessel pruning in zebrafish embryos.

    Directory of Open Access Journals (Sweden)

    Eva Kochhan

    Full Text Available After the initial formation of a highly branched vascular plexus, blood vessel pruning generates a hierarchically structured network with improved flow characteristics. We report here on the cellular events that occur during the pruning of a defined blood vessel in the eye of developing zebrafish embryos. Time-lapse imaging reveals that the connection of a new blood vessel sprout with a previously perfused multicellular endothelial tube leads to the formation of a branched, Y-shaped structure. Subsequently, endothelial cells in parts of the previously perfused branch rearrange from a multicellular into a unicellular tube, followed by blood vessel detachment. This process is accompanied by endothelial cell death. Finally, we show that differences in blood flow between neighboring vessels are important for the completion of the pruning process. Our data suggest that flow induced changes in tubular architecture ensure proper blood vessel pruning.

  12. Large-Eddy simulation of pulsatile blood flow.

    Science.gov (United States)

    Paul, Manosh C; Mamun Molla, Md; Roditi, Giles

    2009-01-01

    Large-Eddy simulation (LES) is performed to study pulsatile blood flow through a 3D model of arterial stenosis. The model is chosen as a simple channel with a biological type stenosis formed on the top wall. A sinusoidal non-additive type pulsation is assumed at the inlet of the model to generate time dependent oscillating flow in the channel and the Reynolds number of 1200, based on the channel height and the bulk velocity, is chosen in the simulations. We investigate in detail the transition-to-turbulent phenomena of the non-additive pulsatile blood flow downstream of the stenosis. Results show that the high level of flow recirculation associated with complex patterns of transient blood flow have a significant contribution to the generation of the turbulent fluctuations found in the post-stenosis region. The importance of using LES in modelling pulsatile blood flow is also assessed in the paper through the prediction of its sub-grid scale contributions. In addition, some important results of the flow physics are achieved from the simulations, these are presented in the paper in terms of blood flow velocity, pressure distribution, vortices, shear stress, turbulent fluctuations and energy spectra, along with their importance to the relevant medical pathophysiology.

  13. Stroke and High Blood Pressure

    Science.gov (United States)

    ... More How High Blood Pressure Can Lead to Stroke Updated:Dec 2,2016 Stroke and high blood ... Changes That Matter • Find Tools & Resources Show Your Stroke Support! Show your stroke support with our new ...

  14. High Blood Pressure Increasing Worldwide

    Science.gov (United States)

    ... page: https://medlineplus.gov/news/fullstory_162977.html High Blood Pressure Increasing Worldwide And health risks may appear even ... of people around the world with elevated or high blood pressure increases, so do the number of deaths linked ...

  15. Medications for High Blood Pressure

    Science.gov (United States)

    ... Consumers Home For Consumers Consumer Updates Medications for High Blood Pressure Share Tweet Linkedin Pin it More sharing options ... age and you cannot tell if you have high blood pressure by the way you feel, so have your ...

  16. High Blood Pressure

    Science.gov (United States)

    ... mmHg People read "118 over 76" millimeters of mercury. Normal Blood Pressure Normal blood pressure for adults ... health. Share your story with other women on Facebook . The Heart Truth campaign offers a variety of ...

  17. Diagnosis of High Blood Pressure

    Medline Plus

    Full Text Available ... page from the NHLBI on Twitter. Diagnosis of High Blood Pressure For most patients, health care providers diagnose high ... are consistently 140/90 mmHg or above. Confirming High Blood Pressure A blood pressure test is easy and painless ...

  18. Diagnosis of High Blood Pressure

    Medline Plus

    Full Text Available ... page from the NHLBI on Twitter. Diagnosis of High Blood Pressure For most patients, health care providers diagnose high ... are consistently 140/90 mmHg or above. Confirming High Blood Pressure A blood pressure test is easy and painless ...

  19. Controlling your high blood pressure

    Science.gov (United States)

    ... medlineplus.gov/ency/patientinstructions/000101.htm Controlling your high blood pressure To use the sharing features on this page, ... JavaScript. Hypertension is another term used to describe high blood pressure. High blood pressure can lead to: Stroke Heart ...

  20. Diagnosis of High Blood Pressure

    Science.gov (United States)

    ... page from the NHLBI on Twitter. Diagnosis of High Blood Pressure For most patients, health care providers diagnose high ... are consistently 140/90 mmHg or above. Confirming High Blood Pressure A blood pressure test is easy and painless ...

  1. Comparison of Modified Chandler, Roller Pump, and Ball Valve Circulation Models for In Vitro Testing in High Blood Flow Conditions: Application in Thrombogenicity Testing of Different Materials for Vascular Applications

    Directory of Open Access Journals (Sweden)

    Wim van Oeveren

    2012-01-01

    We concluded that the Hemobile minimally affects blood and could be adjusted to high blood flows, simulating arterial shear stress. The Hemobile was used to measure hemocompatibility of graft material and showed Dyneema Purity UHMWPE fiber in many ways more hemocompatible than ePTFE and PET.

  2. Salt-gland secretion and blood flow in the goose.

    Science.gov (United States)

    Hanwell, A; Linzell, J L; Peaker, M

    1971-03-01

    1. Salt-gland blood flow in the domestic goose has been measured using a combination of Sapirstein's indicator fractionation technique for organ blood flow and Fegler's thermodilution method for cardiac output.2. Nasal salt secretion was induced by giving 0.5 M-NaCl or 0.154 M-NaCl I.V. or by giving artificial sea water by stomach tube into the proventriculus.3. During secretion, salt-gland blood flow increased from 82.7 +/- 21.9 ml./100 g tissue. min to as high as 2179 ml./100 g. min (mean 1209 +/- 140).4. The rate of secretion in response to salt loading was very variable and was not correlated with the rate of blood flow.5. From the data obtained, it could be calculated that the median values for the percentage extraction of ions from the arterial plasma were Na 15%, K 35%, Cl 21% and water 5.8%.6. Atropine abolished secretion but not the increase in blood flow produced by salt loading.7. Unilateral complete denervation abolished secretion from and the increase in blood flow through the operated but not the control gland.8. Anaesthesia, induced by pentobarbitone sodium, almost completely blocked secretion and the increase in blood flow in the salt-gland in response to salt loading.9. In geese given 0.5 or 0.154 M-NaCl I.V. a positive, significant correlation was found between the total amount of nasal secretion collected over 30 min and the concentrations of Na and Cl in the nasal fluid. However, when the time course of secretion was followed in any one bird, the rate of secretion was inversely related to the concentrations of Na and Cl.10. Harderian gland blood flow was not affected by salt loading.

  3. Fisetin-Rich Extracts of Rhus verniciflua Stokes Improve Blood Flow Rates in Mice Fed Both Normal and High-Fat Diets.

    Science.gov (United States)

    Im, Won Kyun; Park, Hyun Jung; Lee, Kwang Soo; Lee, Jung Hoon; Kim, Young Dong; Kim, Kyeong-Hee; Park, Sang-Jae; Hong, Seokmann; Jeon, Sung Ho

    2016-02-01

    Although it has been previously reported that Rhus verniciflua Stokes (RVS) possesses in vitro anti-inflammatory activity, the precise in vivo mechanisms of RVS extracts and a main active component called fisetin have not been well elucidated. In this study, using newly developed protocols, we prepared urushiol-free but fisetin-enriched RVS extracts and investigated their effects on the vascular immune system. We found that the water-soluble fractions of detoxified RVS with the flavonoid fisetin can inhibit lipopolysaccharide-induced production of nitric oxide (NO) and prostaglandin E2 (PGE2). Furthermore, RVS can reduce inducible nitric oxide synthase and COX2 gene expression levels, which are responsible for NO and PGE2 production, respectively, in RAW264.7 macrophage cells. Because inflammation is linked to the activation of the coagulation system, we hypothesized that RVS and its active component fisetin possess anticoagulatory activities. As expected, we found that both RVS and fisetin could inhibit the coagulation of human peripheral blood cells. Moreover, in vivo RVS treatment could return the retarded blood flow elicited by a high-fat diet (HFD) back to the normal level in mice. In addition, RVS treatment has significantly reduced body weight gained by HFD in mice. Taken together, the fisetin-rich RVS extracts have potential antiplatelet and antiobesity activities and could be used as a functional food ingredient to improve blood circulation.

  4. Transcutaneous measurement of volume blood flow

    Science.gov (United States)

    Daigle, R. E.; Mcleod, F. D.; Miller, C. W.; Histand, M. B.; Wells, M. K.

    1974-01-01

    Blood flow velocity measurements, using Doppler velocimeter, are described. The ability to measure blood velocity using ultrasound is derived from the Doppler effect; the change in frequency which occurs when sound is reflected or transmitted from a moving target. When ultrasound of the appropriate frequency is transmitted through a moving blood stream, the blood cells act as point scatterers of ultrasonic energy. If this scattered ultrasonic energy is detected, it is found to be shifted in frequency according to the velocity of the blood cells, nu, the frequency of the incident sound, f sub o, the speed of sound in the medium, c, and the angle between the sound beam and the velocity vector, o. The relation describing this effect is known as the Doppler equation. Delta f = 2 f sub o x nu x cos alpha/c. The theoretical and experimental methods are evaluated.

  5. Evaluation of high-concentration sevoflurane for induction and nasotracheal intubation without muscle relaxant for infants with different pulmonary blood flow undergoing surgery for congenital heart diseases.

    Science.gov (United States)

    Wang, Kai-Yuan; Wang, Hong-Wu; Xin, Lian-Feng; Wang, Yong-Wang; Xue, Yu-Liang

    2011-12-01

    Inhalational anesthesia with sevoflurane for endotracheal intubation without muscle relaxant is now used widely for pediatric patients. This study assessed the efficacy and safety of induction with high concentration sevoflurane and of nasotracheal intubation without muscle relaxant in infants with increased or decreased pulmonary blood flow (PBF) and undergoing surgery for congenital heart diseases. Fifty-five infants aged 2 - 12 months, weighing 4.7 - 10.0 kg, and scheduled for congenital cardiac surgery were enrolled. Subjects were divided into those with increased (IPBF group, n = 29) and decreased (DPBF group, n = 26) pulmonary blood flow. All infants received inhalational induction with 8% sevoflurane in 100.0% oxygen at a gas flow rate of 6 L/min. Nasotracheal intubation was performed 4 minutes after induction. Sevoflurane vaporization was decreased to 4.0% for placement of a peripheral intravenous line and invasive hemodynamic monitors. Five minutes later, sedatives and muscle relaxant were administered and the vaporizer was adjusted to 2% for maintenance of anesthesia. Bispectral index (BIS) scores, circulatory parameters, satisfactory and successful intubation ratios, adverse reactions, and complications of intubation were recorded. Times to loss of lash and pain reflexes were longer for the DPBF group (P intubation ratios were 93.1% and 61.5% for the IPBF and DPBF groups, respectively (P = 0.008). Successful intubation ratios were 96.6% and 76.9% for the IPBF and DPBF groups, respectively (P = 0.044). Following sevoflurane inhalation, blood pressures decreased significantly in the IPBF group but remained stable in the DPBF group. BIS scores declined to similar stable values, and a "nadir BIS" was recorded for both groups. No obvious adverse reactions or complications of intubation were noted perioperatively. Induction with high concentration sevoflurane, although faster for infants with IPBF, is safe for infants with IPBF or DPBF. However, nasotracheal

  6. Evaluation of high-concentration sevoflurane for induction and nasotracheal intubation without muscle relaxant for infants with d ifferent pulmonary blood flow undergoing surgery for congenitalheart diseases

    Institute of Scientific and Technical Information of China (English)

    WANG Kai-yuan; WANG Hong-wu; XIN Lian-feng; WANG Yong-wang; XUE Yu-liang

    2011-01-01

    Background Inhalational anesthesia with sevoflurane for endotracheal intubation without muscle relaxant is now used widely for pediatric patients.This study assessed the efficacy and safety of induction with high concentration sevoflurane and of nasotracheal intubation without muscle relaxant in infants with increased or decreased pulmonary blood flow (PBF) and undergoing surgery for congenital heart diseases.Methods Fifty-five infants aged 2-12 months,weighing 4.7-10.0 kg,and scheduled for congenital cardiac surgery were enrolled.Subjects were divided into those with increased (IPBF group,n=29) and decreased (DPBF group,n=26) pulmonary blood flow.All infants received inhalational induction with 8% sevoflurane in 100.0% oxygen at a gas flow rate of 6 L/min.Nasotracheal intubation was performed 4 minutes after induction.Sevoflurane vaporization was decreased to 4.0% for placement of a peripheral intravenous line and invasive hemodynamic monitors.Five minutes later,sedatives and muscle relaxant were administered and the vaporizer was adjusted to 2% for maintenance of anesthesia.Bispectral index (BIS) scores,circulatory parameters,satisfactory and successful intubation ratios,adverse reactions,and complications of intubation were recorded.Results Times to loss of lash and pain reflexes were longer for the DPBF group (P <0.01).Satisfactory intubation ratios were 93.1% and 61.5% for the IPBF and DPBF groups,respectively (P=0.008).Successful intubation ratios were 96.6% and 76.9% for the IPBF and DPBF groups,respectively (P=0.044).Following sevoflurane inhalation,blood pressures decreased significantly in the IPBF group but remained stable in the DPBF group.BIS scores declined to similar stable values,and a “nadir BIS” was recorded for both groups.No obvious adverse reactions or complications of intubation were noted perioperatively.Conclusions Induction with high concentration sevoflurane,although faster for infants with IPBF,is safe for infants

  7. Cerebral blood flow in acute mountain sickness

    DEFF Research Database (Denmark)

    Jensen, J B; Wright, Anne; Lassen, N A

    1990-01-01

    Changes in cerebral blood flow (CBF) were measured using the radioactive xenon technique and were related to the development of acute mountain sickness (AMS). In 12 subjects, ascending from 150 to 3,475 m, CBF was 24% increased at 24 h [45.1 to 55.9 initial slope index (ISI) units] and 4% increased...

  8. Effects of aortic irregularities on blood flow.

    Science.gov (United States)

    Prahl Wittberg, Lisa; van Wyk, Stevin; Fuchs, Laszlo; Gutmark, Ephraim; Backeljauw, Philippe; Gutmark-Little, Iris

    2016-04-01

    Anatomic aortic anomalies are seen in many medical conditions and are known to cause disturbances in blood flow. Turner syndrome (TS) is a genetic disorder occurring only in females where cardiovascular anomalies, particularly of the aorta, are frequently encountered. In this study, numerical simulations are applied to investigate the flow characteristics in four TS patient- related aortic arches (a normal geometry, dilatation, coarctation and elongation of the transverse aorta). The Quemada viscosity model was applied to account for the non-Newtonian behavior of blood. The blood is treated as a mixture consisting of water and red blood cells (RBC) where the RBCs are modeled as a convected scalar. The results show clear geometry effects where the flow structures and RBC distribution are significantly different between the aortas. Transitional flow is observed as a jet is formed due to a constriction in the descending aorta for the coarctation case. RBC dilution is found to vary between the aortas, influencing the WSS. Moreover, the local variations in RBC volume fraction may induce large viscosity variations, stressing the importance of accounting for the non-Newtonian effects.

  9. Ergot alkaloids decrease rumen epithelial blood flow

    Science.gov (United States)

    Two experiments were conducted to determine if ergot alkaloids affect blood flow to the absorptive surface of the rumen of steers. Steers (n=8 total) were pair-fed alfalfa cubes at 1.5× NEM and received ground endophyte-infected tall fescue seed (E+) or endophyte-free tall fescue seed (E-) via rumen...

  10. Frequency encoding in renal blood flow regulation

    DEFF Research Database (Denmark)

    Marsh, D.J.; Sosnovtseva, Olga; Pavlov, A.N.

    2005-01-01

    With a model of renal blood flow regulation, we examined consequences of tubuloglomerular feedback (TGF) coupling to the myogenic mechanism via voltage-gated Ca channels. The model reproduces the characteristic oscillations of the two mechanisms and predicts frequency and amplitude modulation...

  11. Blood flow dynamics in the snake spectacle.

    Science.gov (United States)

    van Doorn, Kevin; Sivak, Jacob G

    2013-11-15

    The eyes of snakes are shielded beneath a layer of transparent integument referred to as the 'reptilian spectacle'. Well adapted to vision by virtue of its optical transparency, it nevertheless retains one characteristic of the integument that would otherwise prove detrimental to vision: its vascularity. Given the potential consequence of spectacle blood vessels on visual clarity, one might expect adaptations to have evolved that mitigate their negative impact. Earlier research demonstrated an adaptation to their spatial layout in only one species to reduce the vessels' density in the region serving the foveal and binocular visual fields. Here, we present a study of spectacle blood flow dynamics and provide evidence of a mechanism to mitigate the spectacle blood vessels' deleterious effect on vision by regulation of blood flow through them. It was found that when snakes are at rest and undisturbed, spectacle vessels undergo cycles of dilation and constriction, such that the majority of the time the vessels are fully constricted, effectively removing them from the visual field. When snakes are presented with a visual threat, spectacle vessels constrict and remain constricted for longer periods than occur during the resting cycles, thus guaranteeing the best possible visual capabilities in times of need. Finally, during the snakes' renewal phase when they are generating a new stratum corneum, the resting cycle is abolished, spectacle vessels remain dilated and blood flow remains strong and continuous. The significance of these findings in terms of the visual capabilities and physiology of snakes is discussed.

  12. Blood flow-restricted strength training displays high functional and biological efficacy in women: a within-subject comparison with high-load strength training.

    Science.gov (United States)

    Ellefsen, Stian; Hammarström, Daniel; Strand, Tor A; Zacharoff, Erika; Whist, Jon E; Rauk, Irene; Nygaard, Håvard; Vegge, Geir; Hanestadhaugen, Marita; Wernbom, Mathias; Cumming, Kristoffer T; Rønning, Roar; Raastad, Truls; Rønnestad, Bent R

    2015-10-01

    Limited data exist on the efficacy of low-load blood flow-restricted strength training (BFR), as compared directly to heavy-load strength training (HST). Here, we show that 12 wk of twice-a-week unilateral BFR [30% of one repetition maximum (1RM) to exhaustion] and HST (6-10RM) of knee extensors provide similar increases in 1RM knee extension and cross-sectional area of distal parts of musculus quadriceps femoris in nine untrained women (age 22 ± 1 yr). The two protocols resulted in similar acute increases in serum levels of human growth hormone. On the cellular level, 12 wk of BFR and HST resulted in similar shifts in muscle fiber composition in musculus vastus lateralis, evident as increased MyHC2A proportions and decreased MyHC2X proportions. They also resulted in similar changes of the expression of 29 genes involved in skeletal muscle function, measured both in a rested state following 12 wk of training and subsequent to singular training sessions. Training had no effect on myonuclei proportions. Of particular interest, 1) gross adaptations to BFR and HST were greater in individuals with higher proportions of type 2 fibers, 2) both BFR and HST resulted in approximately four-fold increases in the expression of the novel exercise-responsive gene Syndecan-4, and 3) BFR provided lesser hypertrophy than HST in the proximal half of musculus quadriceps femoris and also in CSApeak, potentially being a consequence of pressure from the tourniquet utilized to achieve blood flow restriction. In conclusion, BFR and HST of knee extensors resulted in similar adaptations in functional, physiological, and cell biological parameters in untrained women.

  13. Diagnosis of High Blood Pressure

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    Full Text Available ... and Obesity Smoking and Your Heart Stroke Send a link to NHLBI to someone by E-MAIL | ... 90 mmHg or above. Confirming High Blood Pressure A blood pressure test is easy and painless and ...

  14. Diagnosis of High Blood Pressure

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    Full Text Available ... of Intramural Research Research Resources Research Meeting Summaries Technology Transfer Clinical Trials What Are Clinical Trials? Children & ... blood pressure is due to other conditions or medicines or if you have primary high blood pressure. ...

  15. Diagnosis of High Blood Pressure

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    Full Text Available ... to keep a written log of all your results. Whenever you have an appointment with the health ... appointments to diagnose high blood pressure. Using the results of your blood pressure test, your health care ...

  16. High Blood Pressure in Pregnancy

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    ... of the baby. Controlling your blood pressure during pregnancy and getting regular prenatal care are important for ... your baby. Treatments for high blood pressure in pregnancy may include close monitoring of the baby, lifestyle ...

  17. What Causes High Blood Cholesterol?

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    ... the NHLBI on Twitter. What Causes High Blood Cholesterol? Many factors can affect the cholesterol levels in your blood. You can control some ... but not others. Factors You Can Control Diet Cholesterol is found in foods that come from animal ...

  18. Diagnosis of High Blood Pressure

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    Full Text Available ... ask for your readings. Blood Pressure Severity and Type Your health care provider usually takes 2–3 ... any other location. Health care providers diagnose this type of high blood pressure by reviewing readings in ...

  19. Diagnosis of High Blood Pressure

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    Full Text Available ... ask for your readings. Blood Pressure Severity and Type Your health care provider usually takes 2–3 ... any other location. Health care providers diagnose this type of high blood pressure by reviewing readings in ...

  20. Diagnosis of High Blood Pressure

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    Full Text Available ... above. Confirming High Blood Pressure A blood pressure test is easy and painless and can be done ... provider’s office or clinic. To prepare for the test: Don’t drink coffee or smoke cigarettes for ...

  1. Diagnosis of High Blood Pressure

    Medline Plus

    Full Text Available ... readings. Blood Pressure Severity and Type Your health care provider usually takes 2–3 readings at several medical appointments to diagnose high blood pressure. Using the ...

  2. Diagnosis of High Blood Pressure

    Medline Plus

    Full Text Available ... and Obesity Smoking and Your Heart Stroke Send a link to NHLBI to someone by E-MAIL | ... 90 mmHg or above. Confirming High Blood Pressure A blood pressure test is easy and painless and ...

  3. Diagnosis of High Blood Pressure

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    Full Text Available ... above. Confirming High Blood Pressure A blood pressure test is easy and painless and can be done ... provider’s office or clinic. To prepare for the test: Don’t drink coffee or smoke cigarettes for ...

  4. Laser speckle contrast imaging to measure changes in cerebral blood flow.

    Science.gov (United States)

    Winship, Ian R

    2014-01-01

    Laser speckle contrast imaging (LSCI) is a powerful tool capable of acquiring detailed maps of blood flow in arteries and veins on the cortical surface. Based on the blurring of laser speckle patterns by the motion of blood cells, LSCI can be combined with a variety of optical imaging preparations to acquire high-spatiotemporal resolution images of blood flow, and track changes in blood flow over time, using relatively simple instrumentation. Here, we describe methods for LSCI of cerebral blood flow via a thin skull imaging preparation in mice or rats. This preparation allows precise semiquantitative mapping of changes in blood flow over time using straightforward surgical protocols and equipment.

  5. Hyperglycemia (High Blood Glucose)

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    Full Text Available ... events, such as eating breakfast, take on exaggerated importance. It's a world where a person needs a ... Living With Diabetes Treatment and Care Blood Glucose Testing Checking Your Blood Glucose A1C and eAG Hypoglycemia ( ...

  6. Intraoperative multi-exposure speckle imaging of cerebral blood flow.

    Science.gov (United States)

    Richards, Lisa M; Kazmi, Sm Shams; Olin, Katherine E; Waldron, James S; Fox, Douglas J; Dunn, Andrew K

    2017-01-01

    Multiple studies have demonstrated that laser speckle contrast imaging (LSCI) has high potential to be a valuable cerebral blood flow monitoring technique during neurosurgery. However, the quantitative accuracy and sensitivity of LSCI is limited, and highly dependent on the exposure time. An extension to LSCI called multi-exposure speckle imaging (MESI) overcomes these limitations, and was evaluated intraoperatively in patients undergoing brain tumor resection. This clinical study ( n = 8) recorded multiple exposure times from the same cortical tissue area spanning 0.5-20 ms, and evaluated images individually as single-exposure LSCI and jointly using the MESI model. This study demonstrated that the MESI estimates provided the broadest flow sensitivity for sampling the flow magnitude in the human brain, closely followed by the shorter exposure times. Conservation of flow analysis on vascular bifurcations was used to validate physiological accuracy, with highly conserved flow estimates (blood flow changes after tissue cautery. Results from this study demonstrate that intraoperative MESI can be performed with high quantitative accuracy and sensitivity for cerebral blood flow monitoring.

  7. Abnormality in cerebellar blood flow in solo vertigo patients

    Energy Technology Data Exchange (ETDEWEB)

    Nagahori, Takeshi [Shakaihoken Takaoka Hospital, Toyama (Japan); Nishijima, Michiharu; Endo, Shunro; Takaku, Akira

    1997-03-01

    Little is known about the blood flow of the vertebrobasilar system as a cause of vertigo and dizziness. We used Xe-CT to study cerebellar blood flow in 53 patients who ranged in age from 35 to 85 years. The patients were divided into two groups. One of them was the vertigo group that comprised 28 patients with rotatory sensation, and the other, the non-vertigo group of 25 patients with a sensation other than rotation. At the stage of severe symptoms, there was decreased cerebellar blood flow in all patients of both, the vertigo and the non-vertigo groups, and a decrease in the bilateral cerebellar hemisphere was observed in five patients and in a unilateral hemisphere in three patients of the vertigo group. By comparison, in the non-vertigo group, unilateral decrease of cerebellar blood flow was observed in only one patient, and a bilateral decrease in five. At the stage of severe symptoms, the mean regional cerebellar blood flow was 40.5{+-}8.0 ml/100 g/min (n=16 sides) in the vertigo group and 45.3{+-}9.5 ml/100 g/min (n=12 sides) in the non-vertigo group. At the stage of moderate symptoms, blood flow image was normal in four of 14 vertigo patients and in seven of 12 non-vertigo patients. The mean regional blood flow was 47.8{+-}8.6 ml/100 g/min (n=28 sides) in the vertigo group and 47.1{+-}5.1 ml/100 g/min (n=24 sides) in the non-vertigo group. At the asymptomatic stage, a high proportion of normal blood flow images (nine of 16 vertigo patients and 10 of 10 non-vertigo patients) was observed. The mean regional cerebellar blood flow was 51.6{+-}10.7 ml/100 g/min (n=32 sides) in the vertigo group and 52.8{+-}8.5 ml/100 g/min (n=20 sides) in the non-vertigo group. This study demonstrates that a unilateral or bilateral decrease in blood flow of the vertebrobasilar system may cause vertigo and dizziness. It also shows that Xe-CT of the cerebellum may be a valuable examination modality for the diagnosis and treatment of vertigo and dizziness. (author)

  8. Blood flow restricted exercise and vascular function.

    Science.gov (United States)

    Horiuchi, Masahiro; Okita, Koichi

    2012-01-01

    It is established that regular aerobic training improves vascular function, for example, endothelium-dependent vasodilatation and arterial stiffness or compliance and thereby constitutes a preventative measure against cardiovascular disease. In contrast, high-intensity resistance training impairs vascular function, while the influence of moderate-intensity resistance training on vascular function is still controversial. However, aerobic training is insufficient to inhibit loss in muscular strength with advancing age; thus, resistance training is recommended to prevent sarcopenia. Recently, several lines of study have provided compelling data showing that exercise and training with blood flow restriction (BFR) leads to muscle hypertrophy and strength increase. As such, BFR training might be a novel means of overcoming the contradiction between aerobic and high-intensity resistance training. Although it is not enough evidence to obtain consensus about impact of BFR training on vascular function, available evidences suggested that BFR training did not change coagulation factors and arterial compliance though with inconsistence results in endothelial function. This paper is a review of the literature on the impact of BFR exercise and training on vascular function, such as endothelial function, arterial compliance, or other potential factors in comparison with those of aerobic and resistance training.

  9. Pulsatile blood flow in Abdominal Aortic Aneurysms

    Science.gov (United States)

    Salsac, Anne-Virginie; Lasheras, Juan C.; Singel, Soeren; Varga, Chris

    2001-11-01

    We discuss the results of combined in-vitro laboratory measurements and clinical observations aimed at determining the effect that the unsteady wall shear stresses and the pressure may have on the growth and eventual rupturing of an Abdominal Aortic Aneurysm (AAA), a permanent bulging-like dilatation occurring near the aortic bifurcation. In recent years, new non-invasive techniques, such as stenting, have been used to treat these AAAs. However, the development of these implants, aimed at stopping the growth of the aneurysm, has been hampered by the lack of understanding of the effect that the hemodynamic forces have on the growth mechanism. Since current in-vivo measuring techniques lack the precision and the necessary resolution, we have performed measurements of the pressure and shear stresses in laboratory models. The models of the AAA were obtained from high resolution three-dimensional CAT/SCANS performed in patients at early stages of the disease. Preliminary DPIV measurements show that the pulsatile blood flow discharging into the cavity of the aneurysm leads to large spikes of pressure and wall shear stresses near and around its distal end, indicating a possible correlation between the regions of high wall shear stresses and the observed location of the growth of the aneurysm.

  10. Blood Flow Restricted Exercise and Vascular Function

    Directory of Open Access Journals (Sweden)

    Masahiro Horiuchi

    2012-01-01

    Full Text Available It is established that regular aerobic training improves vascular function, for example, endothelium-dependent vasodilatation and arterial stiffness or compliance and thereby constitutes a preventative measure against cardiovascular disease. In contrast, high-intensity resistance training impairs vascular function, while the influence of moderate-intensity resistance training on vascular function is still controversial. However, aerobic training is insufficient to inhibit loss in muscular strength with advancing age; thus, resistance training is recommended to prevent sarcopenia. Recently, several lines of study have provided compelling data showing that exercise and training with blood flow restriction (BFR leads to muscle hypertrophy and strength increase. As such, BFR training might be a novel means of overcoming the contradiction between aerobic and high-intensity resistance training. Although it is not enough evidence to obtain consensus about impact of BFR training on vascular function, available evidences suggested that BFR training did not change coagulation factors and arterial compliance though with inconsistence results in endothelial function. This paper is a review of the literature on the impact of BFR exercise and training on vascular function, such as endothelial function, arterial compliance, or other potential factors in comparison with those of aerobic and resistance training.

  11. Ocular Blood Flow and Normal Tension Glaucoma

    Directory of Open Access Journals (Sweden)

    Ning Fan

    2015-01-01

    Full Text Available Normal tension glaucoma (NTG is known as a multifactorial optic neuropathy characterized by progressive retinal ganglion cell death and glaucomatous visual field loss, even though the intraocular pressure (IOP does not exceed the normal range. The pathophysiology of NTG remains largely undetermined. It is hypothesized that the abnormal ocular blood flow is involved in the pathogenesis of this disease. A number of evidences suggested that the vascular factors played a significant role in the development of NTG. In recent years, the new imaging techniques, fluorescein angiography, color Doppler imaging (CDI, magnetic resonance imaging (MRI, and laser speckle flowgraphy (LSFG, have been used to evaluate the ocular blood flow and blood vessels, and the impaired vascular autoregulation was found in patients with NTG. Previous studies showed that NTG was associated with a variety of systemic diseases, including migraine, Alzheimer’s disease, primary vascular dysregulation, and Flammer syndrome. The vascular factors were involved in these diseases. The mechanisms underlying the abnormal ocular blood flow in NTG are still not clear, but the risk factors for glaucomatous optic neuropathy likely included oxidative stress, vasospasm, and endothelial dysfunction.

  12. Dexmedetomidine decreases the oral mucosal blood flow.

    Science.gov (United States)

    Kawaai, Hiroyoshi; Yoshida, Kenji; Tanaka, Eri; Togami, Kohei; Tada, Hitoshi; Ganzberg, Steven; Yamazaki, Shinya

    2013-12-01

    There is an abundance of blood vessels in the oral cavity, and intraoperative bleeding can disrupt operations. There have been some interesting reports about constriction of vessels in the oral cavity, one of which reported that gingival blood flow in cats is controlled by sympathetic α-adrenergic fibres that are involved with vasoconstriction. Dexmedetomidine is a sedative and analgesic agent that acts through the α-2 adrenoceptor, and is expected to have a vasoconstrictive action in the oral cavity. We have focused on the relation between the effects of α-adrenoceptors by dexmedetomidine and vasoconstriction in oral tissues, and assessed the oral mucosal blood flow during sedation with dexmedetomidine. The subjects comprised 13 healthy male volunteers, sedated with dexmedetomidine in a loading dose of 6 μg/kg/h for 10 min and a continuous infusion of 0.7 μg/kg/h for 32 min. The mean arterial pressure (MAP), heart rate (HR), cardiac output (CO), stroke volume (SV), systemic vascular resistance (SVR), and palatal mucosal blood flow (PMBF) were measured at 0, 5, 10, 12, 22, and 32 min after the start of the infusion. The HR, CO, and PBMF decreased significantly during the infusion even though there were no differences in the SV. The SVR increased significantly but the PMBF decreased significantly. In conclusion, PMBF was reduced by the mediating effect of dexmedetomidine on α-2 adrenoceptors.

  13. High Blood Pressure

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    ... giving Gift and estate planning Circle of Champions Corporate sponsorship Join us at an event The Hope ... blood pressure is the #2 cause of kidney failure. It accounts for about one-fourth of all ...

  14. Hyperglycemia (High Blood Glucose)

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    Full Text Available ... the urine Frequent urination Increased thirst Part of managing your diabetes is checking your blood glucose often. ... how to handle this condition. Medical IDs Many people with diabetes, particularly those who use insulin, should ...

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  16. Hyperglycemia (High Blood Glucose)

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    Full Text Available ... the urine Frequent urination Increased thirst Part of managing your diabetes is checking your blood glucose often. ... also help. Work with your dietitian to make changes in your meal plan. If exercise and changes ...

  17. Hyperglycemia (High Blood Glucose)

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  18. Hyperglycemia (High Blood Glucose)

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  19. Hyperglycemia (High Blood Glucose)

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    Full Text Available ... Complications DKA (Ketoacidosis) & Ketones Kidney Disease (Nephropathy) Gastroparesis Mental Health Step On Up Treatment & Care Blood Glucose Testing Medication Doctors, Nurses & More Oral Health & Hygiene Women A1C Insulin Pregnancy ...

  20. Hyperglycemia (High Blood Glucose)

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    Full Text Available ... Disease (Nephropathy) Gastroparesis Mental Health Step On Up Treatment & Care Blood Glucose Testing Medication Doctors, Nurses & More ... us get closer to curing diabetes and better treatments for those living with diabetes. Other Ways to ...

  1. Hyperglycemia (High Blood Glucose)

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    Full Text Available ... Disease (Nephropathy) Gastroparesis Mental Health Step On Up Treatment & Care Blood Glucose Testing Medication Doctors, Nurses & More ... us get closer to curing diabetes and better treatments for those living with diabetes. Other Ways to ...

  2. High Blood Pressure (Hypertension)

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    ... possible. Practice healthy coping techniques, such as muscle relaxation, deep breathing or meditation. Getting regular physical activity ... you monitor your blood pressure at home. Practice relaxation or slow, deep breathing. Practice taking deep, slow ...

  3. Hyperglycemia (High Blood Glucose)

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    Full Text Available ... Step On Up Treatment & Care Blood Glucose Testing Medication Doctors, Nurses & More Oral Health & Hygiene Women A1C ... your doctor may change the amount of your medication or insulin or possibly the timing of when ...

  4. Hyperglycemia (High Blood Glucose)

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    Full Text Available ... How Grant Money is Divided Funding the Next Generation of Brilliant Researchers Our Research Foundation Diabetes Pro: ... they build up in your blood, which can lead to ketoacidosis. Ketoacidosis is life-threatening and needs ...

  5. Hyperglycemia (High Blood Glucose)

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    Full Text Available ... blood glucose early will help you avoid problems associated with hyperglycemia. How Do I Treat Hyperglycemia? You ... Advocacy Take Action Advocacy Priorities News & Events The Cost of Diabetes Advocate Toolkit Call to Congress Research & ...

  6. High Blood Pressure and Women

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    ... blood pressure during a previous pregnancy, have a family history of high blood pressure or mild kidney disease. The combination of birth ... Print (PDF) | Online How to Measure Your Blood Pressure (PDF) Questions To Ask ... FREE digital-only, quarterly magazine for patients, families, and caregivers, which focuses on the prevention and ...

  7. A longitudinal study of cerebral blood flow under hypoxia at high altitude using 3D pseudo-continuous arterial spin labeling

    Science.gov (United States)

    Liu, Wenjia; Liu, Jie; Lou, Xin; Zheng, Dandan; Wu, Bing; Wang, Danny J. J.; Ma, Lin

    2017-01-01

    Changes in cerebral blood flow (CBF) may occur with acute exposure to high altitude; however, the CBF of the brain parenchyma has not been studied to date. In this study, identical magnetic resonance scans using arterial spin labeling (ASL) were performed to study the haemodynamic changes at both sea level and high altitude. We found that with acute exposure to high altitude, the CBF in acute mountain sickness (AMS) subjects was higher (P  0.05) compared with those at sea level. Moreover, magnetic resonance angiography in both AMS and non-AMS subjects showed a significant increase in the cross-sectional areas of the internal carotid, basilar, and middle cerebral arteries on the first day at high altitude. These findings support that AMS may be related to increased CBF rather than vasodilation; these results contradict most previous studies that reported no relationship between CBF changes and the occurrence of AMS. This discrepancy may be attributed to the use of ASL for CBF measurement at both sea level and high altitude in this study, which has substantial advantages over transcranial Doppler for the assessment of CBF. PMID:28240265

  8. What Is High Blood Pressure?

    Science.gov (United States)

    ... Disease Venous Thromboembolism Aortic Aneurysm More What is High Blood Pressure? Updated:Oct 31,2016 First, let’s define high ... resources . This content was last reviewed October 2016. High Blood Pressure • Home • Get the Facts About HBP Introduction What ...

  9. Red blood cell clusters in Poiseuille flow

    Science.gov (United States)

    Ghigliotti, Giovanni; Selmi, Hassib; Misbah, Chaouqi; Elasmi, Lassaad

    2011-11-01

    We present 2D numerical simulations of sets of vesicles (closed bags of a lipid bilayer membrane) in a parabolic flow, a setup that mimics red blood cells (RBCs) in the microvasculature. Vesicles, submitted to sole hydrodynamical interactions, are found to form aggregates (clusters) of finite size. The existence of a maximal cluster size is pointed out and characterized as a function of the flow intensity and the swelling ratio of the vesicles. Moreover bigger clusters move at lower velocity, a fact that may prove of physiological interest. These results quantify previous observations of the inhomogeneous distribution of RBCs in vivo (Gaehtgens et al., Blood Cells 6 - 1980). An interpretation of the phenomenon is put forward based on the presence of boli (vortices) between vesicles. Both the results and the explanation can be transposed to the three-dimensional case.

  10. An analysis of the sluicing gate in pulmonary blood flow.

    Science.gov (United States)

    Fung, Y C; Zhuang, F Y

    1986-05-01

    For pulmonary blood flow in zone 2 condition, in which the blood pressure in the venule (pven) is lower than the alveolar gas pressure (pA), the blood exiting from the capillary sheet and entering a venule must go through a sluicing gate. The sluicing gate exists because the venule remains patent while the capillaries will collapse when the static pressure of blood falls below the alveolar gas pressure. In the original theory of sheet flow the effect of the tension in the interalveolar septa on the flow through the sluicing gate was ignored. Since the tension multiplied by the curvature of the membrane is equivalent to a lateral pressure tending to open the gate, and since the curvature of the capillary wall is high in the gate region, this effect may be important. The present analysis improves the original theory and demonstrates that the effect of membrane tension is to cause flow to increase when the venous pressure continues to decrease. The shape of the sluicing gate resembles that of a venturi tube, and can be determined by an iterative integration of the differential equations. The result forms an important link in the theory of pulmonary blood flow in zone 2 condition.

  11. Effects of Aortic Irregularities on the Blood Flow

    Science.gov (United States)

    Gutmark-Little, Iris; Prahl-Wittberg, Lisa; van Wyk, Stevin; Mihaescu, Mihai; Fuchs, Laszlo; Backeljauw, Philippe; Gutmark, Ephraim

    2013-11-01

    Cardiovascular defects characterized by geometrical anomalies of the aorta and its effect on the blood flow are investigated. The flow characteristics change with the aorta geometry and the rheological properties of the blood. Flow characteristics such as wall shear stress often play an important role in the development of vascular disease. In the present study, blood is considered to be non-Newtonian and is modeled using the Quemada model, an empirical model that is valid for different red blood cell loading. Three patient-specific aortic geometries are studied using Large Eddy Simulations (LES). The three geometries represent malformations that are typical in patients populations having a genetic disorder called Turner syndrome. The results show a highly complex flow with regions of recirculation that are enhanced in two of the three aortas. Moreover, blood flow is diverted, due to the malformations, from the descending aorta to the three side branches of the arch. The geometry having an elongated transverse aorta has larger areas of strong oscillatory wall shear stress.

  12. Deterministic Aperiodic Sickle Cell Blood Flows

    Science.gov (United States)

    Atsaves, Louis; Harris, Wesley

    2013-11-01

    In this paper sickle cell blood flow in the capillaries is modeled as a hydrodynamical system. The hydrodynamical system consists of the axisymmetric unsteady, incompressible Navier-Stokes equations and a set of constitutive equations for oxygen transport. Blood cell deformation is not considered in this paper. The hydrodynamical system is reduced to a system of non-linear partial differential equations that are then transformed into a system of three autonomous non-linear ordinary differential equations and a set of algebraic equations. We examine the hydrodynamical system to discern stable/unstable, periodic/nonperiodic, reversible/irreversible properties of the system. The properties of the solutions are driven in large part by the coefficients of the governing system of equations. These coefficients depend on the physiological properties of the sickle cell blood. The chaotic nature of the onset of crisis in sickle cell patients is identified. Research Assistant.

  13. Computational Analysis of Human Blood Flow

    Science.gov (United States)

    Panta, Yogendra; Marie, Hazel; Harvey, Mark

    2009-11-01

    Fluid flow modeling with commercially available computational fluid dynamics (CFD) software is widely used to visualize and predict physical phenomena related to various biological systems. In this presentation, a typical human aorta model was analyzed assuming the blood flow as laminar with complaint cardiac muscle wall boundaries. FLUENT, a commercially available finite volume software, coupled with Solidworks, a modeling software, was employed for the preprocessing, simulation and postprocessing of all the models.The analysis mainly consists of a fluid-dynamics analysis including a calculation of the velocity field and pressure distribution in the blood and a mechanical analysis of the deformation of the tissue and artery in terms of wall shear stress. A number of other models e.g. T branches, angle shaped were previously analyzed and compared their results for consistency for similar boundary conditions. The velocities, pressures and wall shear stress distributions achieved in all models were as expected given the similar boundary conditions. The three dimensional time dependent analysis of blood flow accounting the effect of body forces with a complaint boundary was also performed.

  14. High Blood Calcium (Hypercalcemia)

    Science.gov (United States)

    ... as well as kidney function and levels of calcium in your urine. Your provider may do other tests to further assess your condition, such as checking your blood levels of phosphorus (a mineral). Imaging studies also may be helpful, such as bone ...

  15. Hyperglycemia (High Blood Glucose)

    Medline Plus

    Full Text Available ... work with your doctor to find the safest way for you to lower your blood glucose level. Cutting down on the amount of food you eat might also help. Work with your dietitian to make changes in your meal plan. If exercise and changes ...

  16. Hyperglycemia (High Blood Glucose)

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    Full Text Available ... Neuropathy Foot Complications DKA (Ketoacidosis) & Ketones Kidney Disease (Nephropathy) Gastroparesis Mental Health Step On Up Treatment & Care Blood Glucose Testing Medication Doctors, Nurses & More Oral Health & Hygiene Women A1C Insulin Pregnancy 8 Tips for Caregivers Health Insurance Health Insurance ...

  17. Hyperglycemia (High Blood Glucose)

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    Full Text Available ... and Care > Blood Glucose Testing Share: Print Page Text Size: A A A Listen En Español Hyperglycemia ( ... Advocacy Take Action Advocacy Priorities News & Events The Cost of Diabetes Advocate ... Resources Shop Diabetes » Close nonprofit software

  18. Effect of high dose fish oil supplementation on cerebral blood flow and cognitive performance in patients with mild cognitive impairment: a proof of concept study

    NARCIS (Netherlands)

    Rest, van de O.; Claassen, J.A.; Kessels, R.P.C.; Geleijnse, J.M.; Olde Rikkert, M.G.M.; Groot, de C.P.G.M.

    2013-01-01

    Objective: The current study aimed to examine the effect of n-3 polyunsaturated fatty acids (PUFAs) on cerebral blood flow and age-related loss of cognitive functioning in subjects diagnosed with mild cognitive impairment (MCI). Design, setting and participants: A total of 20 patients with single or

  19. Blood flow measurements and clot detection with nearinfrared spectroscopy

    OpenAIRE

    Rossow, MJ; Gatto, R.; D'amico, E.; Mantulin, WW; Gratton, E

    2006-01-01

    Detecting impeded blood flow and locating the clot causing it is a major challenge in neurosurgery. We propose an instrument that uses near-infrared spectroscopy to simultaneously detect clots and measure blood flow. © 2006 Optical Society of America.

  20. Common High Blood Pressure Myths

    Science.gov (United States)

    ... Artery Disease Venous Thromboembolism Aortic Aneurysm More Common High Blood Pressure Myths Updated:Dec 9,2016 Knowing the facts ... health. This content was last reviewed October 2016. High Blood Pressure • Home • Get the Facts About HBP Introduction What ...

  1. Effect of warming and flow rate conditions of blood warmers on red blood cell integrity.

    Science.gov (United States)

    Poder, T G; Pruneau, D; Dorval, J; Thibault, L; Fisette, J-F; Bédard, S K; Jacques, A; Beauregard, P

    2016-11-01

    Fluid warmers are routinely used to reduce the risk of hypothermia and cardiac complications associated with the infusion of cold blood products. However, warming blood products could generate haemolysis. This study was undertaken to compare the impact of temperature of blood warmers on the per cent haemolysis of packed red blood cells (RBCs) heated at different flow rates as well as non-flow conditions. Infusion warmers used were calibrated at 41·5°C ± 0·5°C and 37·5°C ± 0·5°C. Cold RBC units stored at 4°C in AS-3 (n = 30), aged 30-39 days old, were divided into half units before being allocated under two different scenarios (i.e. infusion pump or syringe). Blood warmers were effective to warm cold RBCs to 37·5°C or 41·5°C when used in conjunction with an infusion pump at flow rate up to 600 ml/h. However, when the warmed blood was held in a syringe for various periods of time, such as may occur in neonatal transfusions, the final temperature was below the expected requirements with measurement as low as 33·1°C. Increasing the flow with an infusion pump increased haemolysis in RBCs from 0·2% to up to 2·1% at a flow rate of 600 ml/h regardless of the warming device used (P < 0·05). No relevant increase of haemolysis was observed using a syringe. The use of a blood warmer adjusted to 41·5°C is probably the best choice for reducing the risk of hypothermia for the patient without generating haemolysis. However, we should be cautious with the use of an infusion pump for RBC transfusion, particularly at high flow rates. © 2016 International Society of Blood Transfusion.

  2. The impact of high-frequency magnetic stimulation of peripheral nerves: muscle hardness, venous blood flow, and motor function of upper extremity in healthy subjects.

    Science.gov (United States)

    Okudera, Yoshihiko; Matsunaga, Toshiki; Sato, Mineyoshi; Chida, Satoaki; Hatakeyama, Kazutoshi; Watanabe, Motoyuki; Shimada, Yoichi

    2015-01-01

    The purpose of this study was to investigate the impact of high-frequency peripheral nerve magnetic stimulation on the upper limb function. Twenty-five healthy adults (16 men and 9 women) participated in this study. The radial nerve of the non-dominant hand was stimulated by high-frequency magnetic stimulation device. A total of 600 impulses were applied at a frequency of 20 Hz and intensity of 1.2 resting motor threshold (rMT). At three time points (before, immediately after, and 15 min after stimulation), muscle hardness of the extensor digitorum muscle on the stimulated side was measured using a mechanical tissue hardness meter and a shear wave imaging device, cephalic venous blood flow on the stimulated side was measured using an ultrasound system, and the Box and Block test (BBT) was performed. Mechanical tissue hardness results did not show any significant differences between before, immediately after, and 15 min after stimulation. Measurements via shear wave imaging showed that muscle hardness significantly decreased both immediately and 15 min after stimulation compared to before stimulation (P nerve magnetic stimulation can achieve effects similar to electrical stimulation in a less invasive manner, and may therefore become an important element in next-generation rehabilitation.

  3. High Blood Cholesterol Prevention

    Science.gov (United States)

    ... Million Hearts® WISEWOMAN Program Prevention and Management of High LDL Cholesterol: What You Can Do Recommend on ... like eating a healthy diet, can help prevent high cholesterol. High low-density lipoprotein (LDL) cholesterol increases ...

  4. Hydrogen sulfide induces apoptosis of pulmonary artery smooth muscle cell in rats with pulmonary hypertension induced by high pulmonary blood flow

    Institute of Scientific and Technical Information of China (English)

    LI Wei; JIN Hong-fang; LIU Die; SUN Jing-hui; JIAN Pei-jun; LI Xiao-hui; TANG Chao-shu; DU Jun-bao

    2009-01-01

    Background Abnormal apoptosis of pulmonary artery smooth muscle cells (PASMCs) is an important pathophysiological process in the pulmonary artery structural remodeling and pulmonary hypertension. We investigated possible effect of endogenous hydrogen sulfide (H_2S) on apoptosis of PASMCs during the development of pulmonary hypertension induced by high pulmonary blood flow.Methods Thirty-nine male Sprague-Dawley rats were randomly assigned to 4-week control, 4-week shunt, 4-week shunt+propargylglycine (PPG), 11-week control, 11-week shunt and 11-week shunt+sodium hydrosulfide (NaHS) groups. Rats in 4-week shunt, 4-week shunt+PPG, 11-week shunt and 11-week shunt+NaHS groups underwent an abdominal aorta-inferior vena cava shunt. Rats in 4-week shunt+PPG group were intraperitoneally injected with PPG, an inhibitor of endogenous H_2S production, for 4 weeks. Rats in 11-week shunt+NaHS group were intraperitoneally injected with NaHS, a H_2S donor, for 11 weeks. Lung tissue H_2S was evaluated by sulfide-sensitive electrode. Apoptosis of PASMCs were detected by terminal deoxynucleotidyl transferase mediated dUTP nick end labelling (TUNEL). Expressions of Fas, bcl-2 and caspase-3 in the PASMCs were analyzed with immunochemical staining.Results Four weeks after the shunting operation, the apoptosis of PASMCs and expression of Fas and caspase-3 were significantly decreased (P<0.01), but expression of bcl-2 increased significantly (P<0.01). PPG administration further inhibited the apoptosis of PASMCs, downregulated the expression of Fas and caspase-3 (P <0.01), but increased the expression of bcl-2 (P<0.01). After 11 weeks of shunting operation, the apoptosis of PASMCs and expression of Fas and caspase-3 were significantly decreased (P <0.01), but expression of bcl-2 increased obviously (P <0.01). NaHS administration significantly increased the apoptosis of PASMCs, upregulated the expression of Fas and caspase-3, but inhibited the expression of bcl-2.Conclusions H_2S induces

  5. Glial and neuronal control of brain blood flow

    DEFF Research Database (Denmark)

    Attwell, David; Buchan, Alastair M; Charpak, Serge

    2010-01-01

    Blood flow in the brain is regulated by neurons and astrocytes. Knowledge of how these cells control blood flow is crucial for understanding how neural computation is powered, for interpreting functional imaging scans of brains, and for developing treatments for neurological disorders. It is now...... in our understanding of cerebral blood flow control have important implications for the development of new therapeutic approaches....

  6. Accurate blood flow measurements: are artificial tracers necessary?

    Science.gov (United States)

    Poelma, Christian; Kloosterman, Astrid; Hierck, Beerend P; Westerweel, Jerry

    2012-01-01

    Imaging-based blood flow measurement techniques, such as particle image velocimetry, have become an important tool in cardiovascular research. They provide quantitative information about blood flow, which benefits applications ranging from developmental biology to tumor perfusion studies. Studies using these methods can be classified based on whether they use artificial tracers or red blood cells to visualize the fluid motion. We here present the first direct comparison in vivo of both methods. For high magnification cases, the experiments using red blood cells strongly underestimate the flow (up to 50% in the present case), as compared to the tracer results. For medium magnification cases, the results from both methods are indistinguishable as they give the same underestimation of the real velocities (approximately 33%, based on in vitro reference measurements). These results suggest that flow characteristics reported in literature cannot be compared without a careful evaluation of the imaging characteristics. A method to predict the expected flow averaging behavior for a particular facility is presented.

  7. Accurate blood flow measurements: are artificial tracers necessary?

    Directory of Open Access Journals (Sweden)

    Christian Poelma

    Full Text Available Imaging-based blood flow measurement techniques, such as particle image velocimetry, have become an important tool in cardiovascular research. They provide quantitative information about blood flow, which benefits applications ranging from developmental biology to tumor perfusion studies. Studies using these methods can be classified based on whether they use artificial tracers or red blood cells to visualize the fluid motion. We here present the first direct comparison in vivo of both methods. For high magnification cases, the experiments using red blood cells strongly underestimate the flow (up to 50% in the present case, as compared to the tracer results. For medium magnification cases, the results from both methods are indistinguishable as they give the same underestimation of the real velocities (approximately 33%, based on in vitro reference measurements. These results suggest that flow characteristics reported in literature cannot be compared without a careful evaluation of the imaging characteristics. A method to predict the expected flow averaging behavior for a particular facility is presented.

  8. Decorrelation-based blood flow velocity estimation: effect of spread of flow velocity, linear flow velocity gradients, and parabolic flow.

    NARCIS (Netherlands)

    Lupotti, F.A.; Steen, A.F.W. van der; Mastik, F.; Korte, C.L. de

    2002-01-01

    In recent years, a new method to measure transverse blood flow, based on the decorrelation of the radio frequency (RF) signals has been developed. In this paper, we investigated the influence of nonuniform flow on the velocity estimation. The decorrelation characteristics of transverse blood flow us

  9. Blood flow in healed and inflamed periodontal tissues of dogs

    Energy Technology Data Exchange (ETDEWEB)

    Hock, J.M.; Kim, S.

    1987-01-01

    The objectives of this study were to determine if increased blood flow associated with gingivitis would decrease following resolution of gingival inflammation in dogs with periodontitis; if increased blood flow in inflamed gingiva was associated with changes in the blood flow of alveolar bone, and if blood flow in gingiva and alveolar bone increased if periodontitis was reactivated by ligating teeth. Regional blood flow was measured in dogs with pre-existing periodontitis, using radioisotope-labelled, plastic microspheres. In the first experiment on 4 adult Beagle dogs, teeth in the left jaws were treated to resolve the periodontitis, while teeth in the right jaws were not treated. Gingival and bone blood flow were measured after 12 wk. Blood flow was significantly (p<0.05) lower in non-inflamed healed gingiva (32.1 +- 2.7 ml/min/100 g) than in inflamed gingiva (46.1 +- 5.3 ml/min/100 g). No differences in the blood flow of the alveolar bone underlying inflamed or non-inflamed gingiva were present. In the second experiment, the right mandibular teeth of 5 dogs were treated to resolve periodontitis while teeth in the other quadrants were ligated for 4, 10 or 12 wk. The duration of ligation did not alter blood flow. Gingival blood flow around ligated maxillary and mandibular teeth was comparable and approximately 54% higher than around non-ligated teeth (p<0.03). The difference in blood flow between gingiva with G.I.>1 and gingiva with G.I.<2 was significant (p<0.04). Blood flow in bone was not altered by changes in the inflammatory status of the overlying gingiva. The findings suggest that changes in blood flow associated with inflammation are reversible and that blood flow alveolar bone is regulated independently of gingival blood flow.

  10. Skin blood flow changes during apneic spells in preterm infants

    NARCIS (Netherlands)

    Suichies, H.E.; Aarnoudse, J.G.; Okken, A.; Jentink, H.W.; Mul, de F.F.M.; Greve, J.

    1989-01-01

    Changes in skin blood flow during apneic spells were determined in 18 preterm infants using a diode laser Doppler flow meter without light conducting fibres. Heart rate, nasal air flow, impedance pneumography, skin and incubator temperature and laser Doppler skin blood flow were recorded simultaneou

  11. Absolute quantification of myocardial blood flow.

    Science.gov (United States)

    Yoshinaga, Keiichiro; Manabe, Osamu; Tamaki, Nagara

    2016-07-21

    With the increasing availability of positron emission tomography (PET) myocardial perfusion imaging, the absolute quantification of myocardial blood flow (MBF) has become popular in clinical settings. Quantitative MBF provides an important additional diagnostic or prognostic information over conventional visual assessment. The success of MBF quantification using PET/computed tomography (CT) has increased the demand for this quantitative diagnostic approach to be more accessible. In this regard, MBF quantification approaches have been developed using several other diagnostic imaging modalities including single-photon emission computed tomography, CT, and cardiac magnetic resonance. This review will address the clinical aspects of PET MBF quantification and the new approaches to MBF quantification.

  12. Nonlinear interactions in renal blood flow regulation

    DEFF Research Database (Denmark)

    Marsh, Donald J.; Sosnovtseva, Olga; Chon, Ki H.

    2005-01-01

    , identical except for the strength of TGF input, with a third, fixed resistance segment representing prearteriolar vessels. The two arteriolar segments are electrically coupled. The arteriolar, glomerular, and tubular models are linked; TGF modulates arteriolar circumference, which determines vascular...... resistance and glomerular capillary pressure. The model couples TGF input to voltage-gated Ca channels. It predicts autoregulation of GFR and renal blood flow, matches experimental measures of tubular pressure and macula densa NaCl concentration, and predicts TGF-induced oscillations and a faster smaller...

  13. Hyperglycemia (High Blood Glucose)

    Medline Plus

    Full Text Available ... and Learning About Prediabetes Type 2 Diabetes Risk Test Lower Your Risk Healthy Eating Overweight Smoking High ... excused. 86 million Americans have prediabetes. Take the test. Know where you stand. sticky en -- Chef Ronaldo's ...

  14. Hyperglycemia (High Blood Glucose)

    Medline Plus

    Full Text Available ... and Learning About Prediabetes Type 2 Diabetes Risk Test Lower Your Risk Healthy Eating Overweight Smoking High ... You at Risk? Diagnosis Lower Your Risk Risk Test Alert Day Prediabetes My Health Advisor Tools to ...

  15. Diagnosis of High Blood Pressure

    Medline Plus

    Full Text Available ... Planning, & Legislative Advisory Committees Jobs Contact Us FAQs Home » Health Information for the Public » Health Topics » High ... also may ask you to check readings at home or at other locations that have blood pressure ...

  16. Diagnosis of High Blood Pressure

    Medline Plus

    Full Text Available ... Explore High Blood Pressure What Is... Other Names Causes Who Is at Risk Signs & Symptoms Diagnosis Treatments Prevention Living With Clinical Trials Links Related Topics Atherosclerosis DASH Eating Plan Overweight and Obesity Smoking and Your Heart ...

  17. Diagnosis of High Blood Pressure

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    Full Text Available ... Health care providers diagnose this type of high blood pressure by reviewing readings in the office and readings taken anywhere else. ... The Heart Truth ® —a national heart disease awareness campaign for ...

  18. Diagnosis of High Blood Pressure

    Medline Plus

    Full Text Available ... to check readings at home or at other locations that have blood pressure equipment and to keep ... office compared with readings taken in any other location. Health care providers diagnose this type of high ...

  19. Diagnosis of High Blood Pressure

    Medline Plus

    Full Text Available ... provider usually takes 2–3 readings at several medical appointments to diagnose high blood pressure. Using the ... Researchers believe stress, which can occur during the medical appointment, causes white coat hypertension. Rate This Content: ...

  20. Diagnosis of High Blood Pressure

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    Full Text Available ... Events Spokespeople Email Alerts E-Newsletters About NHLBI Organization NHLBI Director Budget, Planning, & Legislative Advisory Committees Jobs Contact Us FAQs Home » Health Information for the Public » Health Topics » High Blood Pressure » ...

  1. Regional cerebral blood flow in schizophrenics

    Energy Technology Data Exchange (ETDEWEB)

    Uchino, J.; Ohta, Y.; Nakane, Y.; Mori, H.; Hirota, N.; Yonekura, M.

    1987-01-01

    The present study on schizophrenics dealt with the relationship of regional cerebral blood flow (rCBF) to age, disease duration, and treatment length with chlorpromazine hydrochloride (CPZ). Regional cerebral blood flow in 28 cerebral regions of interest was measured by iv injection of /sup 133/X in 54 schizophrenic patients and 39 healthy volunteers. Neither age nor dosage of CPZ significantly influenced rCBF. All patients, including 11 treated for a short period of time (6 months or less), were characterized by having a decreased rCBF over the whole cerebrum. Thirty-four patients treated for a long period of time (2 years or more) had a varied rCBF distribution in the left hemisphere, with the most predominant feature being the decrease in rCBF in the frontal lobe (i.e., hypofrontality); however, there was no linear correlation between rCBF and disease duration. A decreased rCBE in the right occipital region was seen in patients with paranoid schizophrenia, suggesting that manifestations of symptoms may depend on disturbed regions. These results suggest that cerebral dysfunction in schizophrenic patients may not be restricted to the frontal lobe, but cover the whole cerebrum, and that nonuniform dysfunction in various regions of the cerebrum, including the frontal lobe, may be involved in manifestations of symptoms.

  2. High Blood Pressure and Kidney Disease

    Science.gov (United States)

    ... Disease Mineral & Bone Disorder View All Content High Blood Pressure & Kidney Disease What is high blood pressure? Blood pressure is the force of blood ... million filtering units called nephrons. How does high blood pressure affect the kidneys? High blood pressure can ...

  3. High Blood Pressure Prevention

    Science.gov (United States)

    ... or "no added salt." Look for the sodium content in milligrams and the Percent Daily Value. Aim for foods that are less than 5 percent of the Daily Value of sodium. Foods with 20 percent or more Daily Value of sodium are considered high. To learn more about reading nutrition labels, see ...

  4. When Blood Sugar Is Too High

    Science.gov (United States)

    ... Help Someone Who's Being Bullied? Volunteering When Blood Sugar Is Too High KidsHealth > For Teens > When Blood ... often can be unhealthy. What Is High Blood Sugar? The blood glucose level is the amount of ...

  5. Microheterogeneity of blood flow in the rat urinary bladder

    Energy Technology Data Exchange (ETDEWEB)

    Kimura, Takahiro [Kawasaki Medical School, Kurashiki, Okayama (Japan)

    2002-08-01

    The microheterogeneity of blood flow in the mucous membrane of the urinary bladder and that in the detrusor muscle in anesthetized rats (n=8) were investigated at an extremely high spatial resolution (0.1 x 0.1 mm{sup 2}) using digital radiography combined with the {sup 3}H-labeled desmethylimipramine deposition technique. The spatial pattern of flow distribution was quantified by the coefficient of variation regional flow (CV: standard deviation/mean). The results showed muscle blood flow to be lower than mucous blood flow (muscle: mucosa=2.9:5), with the distribution of the former being more heterogeneous than that of the latter (CV in muscle vs. CV in mucosa=0.33{+-}0.033 vs. 0.16{+-}0.019, p<0.001) at the capillary level. It was therefore considered that the muscle would more easily experience mechanical irritation and be more easily influenced by arterial tonus than the mucous membrane, ant it was thought that this difference reflected a difference in regional perfusion. (author)

  6. Blood flow simulation on a role for red blood cells in platelet adhesion

    Science.gov (United States)

    Shimizu, Kazuya; Sugiyama, Kazuyasu; Takagi, Shu

    2016-11-01

    Large-scale blood flow simulations were conducted and a role for red blood cells in platelet adhesion was discussed. The flow conditions and hematocrit values were set to the same as corresponding experiments, and the numerical results were compared with the measurements. Numerical results show the number of platelets adhered on the wall is increased with the increase in hematocrit values. The number of adhered platelets estimated from the simulation was approximately 28 (per 0.01 square millimeter per minute) for the hematocrit value of 20%. These results agree well with the experimental results qualitatively and quantitatively, which proves the validity of the present numerical model including the interaction between fluid and many elastic bodies and the modeling of platelet adhesion. Numerical simulation also reproduces the behavior of red blood cells in the blood flow and their role in platelet adhesion. Red blood cells deform to a flat shape and move towards channel center region. In contrast, platelets are pushed out and have many chances to contact with the wall. As a result, the large number of adhered platelets is observed as hematocrit values becomes high. This result indicates the presence of red blood cells plays a crucial role in platelet adhesion.

  7. Femoral Blood Flow and Cardiac Output During Blood Flow Restricted Leg Press Exercise

    Science.gov (United States)

    Everett, M. E.; Hackney, K.; Ploutz-Snyder, L.

    2011-01-01

    Low load blood flow restricted resistance exercise (LBFR) causes muscle hypertrophy that may be stimulated by the local ischemic environment created by the cuff pressure. However, local blood flow (BF) during such exercise is not well understood. PURPOSE: To characterize femoral artery BF and cardiac output (CO) during leg press exercise (LP) performed at a high load (HL) and low load (LL) with different levels of cuff pressure. METHODS: Eleven subjects (men/women 4/7, age 31.4+/-12.8 y, weight 68.9+/-13.2 kg, mean+/-SD) performed 3 sets of supine left LP to fatigue with 90 s of rest in 4 conditions: HL (%1-RM/cuff pressure: 80%/0); LL (20%/0); LBFR(sub DBP) (20%/1.3 x diastolic blood pressure, BP); LBFR(sub SBP) (20%/1.3 x supine systolic BP). The cuff remained inflated throughout the LBFR exercise sessions. Artery diameter, velocity time integral (VTI), and stroke volume (SV) were measured using Doppler ultrasound at rest and immediately after each set of exercise. Heart rate (HR) was monitored using a 3-lead ECG. BF was calculated as VTI x vessel cross-sectional area. CO was calculated as HR x SV. The data obtained after each set of exercise were averaged and used for analyses. Multi-level modeling was used to determine the effect of exercise condition on dependent variables. Statistical significance was set a priori at p LL (9.92+/-0.82 cm3) > LBFR(sub dBP)(6.47+/-0.79 cm3) > LBFR(sub SBP) (3.51+/-0.59 cm3). Blunted exercise induced increases occurred in HR, SV, and CO after LBFR compared to HL and LL. HR increased 45% after HL and LL and 28% after LBFR (p<0.05), but SV increased (p<0.05) only after HL. Consequently, the increase (p<0.05) in CO was greater in HL and LL (approximately 3 L/min) than in LBFR (approximately 1 L/min). CONCLUSION: BF during LBFR(sub SBP) was 1/3 of that observed in LL, which supports the hypothesis that local ischemia stimulates the LBFR hypertrophic response. As the cuff did not compress the artery, the ischemia may have occurred

  8. Developmental validation of a novel lateral flow strip test for rapid identification of human blood (Rapid Stain Identification--Blood).

    Science.gov (United States)

    Schweers, Brett A; Old, Jennifer; Boonlayangoor, P W; Reich, Karl A

    2008-06-01

    Human blood is the body fluid most commonly encountered at crime scenes, and blood detection may aid investigators in reconstructing what occurred during a crime. In addition, blood detection can help determine which items of evidence should be processed for DNA-STR testing. Unfortunately, many common substances can cause red-brown stains that resemble blood. Furthermore, many current human blood detection methods are presumptive and prone to false positive results. Here, the developmental validation of a new blood identification test, Rapid Stain Identification--Blood (RSID--Blood), is described. RSID--Blood utilizes two anti-glycophorin A (red blood cell membrane specific protein) monoclonal antibodies in a lateral flow strip test format to detect human blood. We present evidence demonstrating that this test is accurate, reproducible, easy to use, and highly specific for human blood. Importantly, RSID--Blood does not cross-react with ferret, skunk, or primate blood and exhibits no high-dose hook effect. Also, we describe studies on the sensitivity, body fluid specificity, and species specificity of RSID--Blood. In addition, we show that the test can detect blood from a variety of forensic exhibits prior to processing for DNA-STR analysis. In conclusion, we suggest that RSID--Blood is effective and useful for the detection of human blood on forensic exhibits, and offers improved blood detection when compared to other currently used methods.

  9. Blood Flow Imaging in Maternal and Fetal Arteries and Veins

    Science.gov (United States)

    Ricci, S.; Urban, G.; Vergani, P.; Paidas, M. J.; Tortoli, P.

    Maternal and fetal blood circulation has been investigated for nearly a decade through ultrasound (US) techniques. Evaluation of the spectrogram related to a single sample volume has been proven valuable for the assessment of fetal well-being and for prediction of pregnancy complications. In this work, an alternative technique, called Multigate Spectral Doppler Analysis (MSDA), is proposed. In this approach, 128 sample volumes aligned along the same scan line are simultaneously investigated to detect the blood velocity profile with high resolution. Profiles obtained through MSDA reveal features not detectable with the standard US technique, thus representing a more accurate flow signature. Some preliminary illustrative results are reported here.

  10. Cell-cell interaction in blood flow in patients with coronary heart disease (in vitro study)

    Science.gov (United States)

    Malinova, Lidia I.; Simonenko, Georgy V.; Denisova, Tatyana P.; Tuchin, Valery V.

    2007-02-01

    Blood cell-cell and cell-vessel wall interactions are one of the key patterns in blood and vascular pathophysiology. We have chosen the method of reconstruction of pulsative blood flow in vitro in the experimental set. Blood flow structure was studied by PC integrated video camera with following slide by slide analysis. Studied flow was of constant volumetric blood flow velocity (1 ml/h). Diameter of tube in use was comparable with coronary arteries diameter. Glucose solution and unfractured heparin were used as the nonspecial irritants of studied flow. Erythrocytes space structure in flow differs in all groups of patients in our study (men with stable angina pectoris (SAP), myocardial infarction (MI) and practically healthy men (PHM). Intensity of erythrocytes aggregate formation was maximal in patients with SAP, but time of their "construction/deconstruction" at glucose injection was minimal. Phenomena of primary clotting formation in patients with SAP of high function class was reconstructed under experimental conditions. Heparin injection (10 000 ED) increased linear blood flow velocity both in patients with SAP, MI and PHP but modulated the cell profile in the flow. Received data correspond with results of animal model studies and noninvasive blood flow studies in human. Results of our study reveal differences in blood flow structure in patients with coronary heart disease and PHP under irritating conditions as the possible framework of metabolic model of coronary blood flow destabilization.

  11. Cerebral blood flow and metabolism during sleep

    DEFF Research Database (Denmark)

    Madsen, Peter Lund; Vorstrup, S

    1991-01-01

    A review of the current literature regarding sleep-induced changes in cerebral blood flow (CBF) and cerebral metabolic rate (CMR) is presented. Early investigations have led to the notion that dreamless sleep was characterized by global values of CBF and CMR practically at the level of wakefulness......, while rapid eye movement (REM) sleep (dream sleep) was a state characterized by a dramatically increased level of CBF and possibly also of CMR. However, recent investigations firmly contradict this notion. Investigations on CBF and CMR performed during non-REM sleep, taking the effect of different...... levels of sleep into consideration, show that light sleep (stage II) is characterized by global levels of CBF and CMR only slightly reduced by 3-10% below the level associated with wakefulness, whereas CBF and CMR during deep sleep (stage III-IV) is dramatically reduced by 25-44%. Furthermore, recent...

  12. Intraoperative cerebral blood flow imaging of rodents

    Science.gov (United States)

    Li, Hangdao; Li, Yao; Yuan, Lu; Wu, Caihong; Lu, Hongyang; Tong, Shanbao

    2014-09-01

    Intraoperative monitoring of cerebral blood flow (CBF) is of interest to neuroscience researchers, which offers the assessment of hemodynamic responses throughout the process of neurosurgery and provides an early biomarker for surgical guidance. However, intraoperative CBF imaging has been challenging due to animal's motion and position change during the surgery. In this paper, we presented a design of an operation bench integrated with laser speckle contrast imager which enables monitoring of the CBF intraoperatively. With a specially designed stereotaxic frame and imager, we were able to monitor the CBF changes in both hemispheres during the rodent surgery. The rotatable design of the operation plate and implementation of online image registration allow the technician to move the animal without disturbing the CBF imaging during surgery. The performance of the system was tested by middle cerebral artery occlusion model of rats.

  13. High Plasma Levels of Neuropeptide Y Correlate With Good Clinical Outcome But are not Correlated to Cerebral Blood Flow or Vasospasm After Subarachnoid Hemorrhage

    DEFF Research Database (Denmark)

    Rasmussen, Rune; Stavngaard, Trine; Jessing, Iben R;

    2016-01-01

    BACKGROUND AND PURPOSE: Delayed cerebral ischemia (DCI) is a serious and frequent complication following subarachnoid hemorrhage. Treatments with convincing effect are lacking and the pathophysiology behind DCI remains poorly understood. Neuropeptide Y (NPY) is a potent endogenous vasoconstrictor...... and a role of NPY in the development of DCI has been proposed. This study investigated the relationship between plasma-NPY and cerebral blood flow (CBF), cerebral vasospasm, DCI, and clinical outcome. METHODS: In 90 patients with subarachnoid hemorrhage, NPY was measured in peripheral blood days 2 to 11. Any...... occurrence of DCI was recorded and CBF was quantified day 3 and day 8 using computed tomography (CT) perfusion. CT angiography was performed day 8. Clinical outcome was assessed after 3 months. RESULTS: No correlation was found between plasma-NPY and CBF or angiographic vasospasm. The correlation between...

  14. Laser speckle imaging of blood flow in microcirculation

    Energy Technology Data Exchange (ETDEWEB)

    Cheng Haiying; Luo Qingming; Liu Qian; Lu Qiang; Gong Hui; Zeng Shaoqun [Key Laboratory of Biomedical Photonics of Ministry of Education of China, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2004-04-07

    Monitoring the spatio-temporal characteristics of microcirculation is crucial for studying the functional activities of biotissue and the mechanism of disease. However, conventional methods used to measure blood flow suffer from limited spatial resolution or the injection of exogenous substances or the need of scanning to obtain the dynamic of regional blood flow. Laser speckle imaging (LSI) technique makes up these disadvantages by obtaining the regional blood flow distribution with high spatio-temporal resolution without the need to scan. In this paper, LSI was introduced to investigate the dynamic responses of the rat mesenteric microcirculation to an incremental dose of phentolamine. The results showed that when the dose of phentolamine was less than 4 {mu}g ml{sup -1}, local application of phentolamine on the mesentery would increase the blood perfusion as the concentration increased. When the dose increased further, the improvement decreased. At a dose of 200 {mu}g ml{sup -1}, a microcirculation impediment was caused. At the same time, different responses between veinules and arterioles were manifested. These suggested that LSI is promising to be a useful contribution to drug development and testing.

  15. Mapping blood flow directionality in the human brain.

    Science.gov (United States)

    Park, Sung-Hong; Do, Won-Joon; Choi, Seung Hong; Zhao, Tiejun; Bae, Kyongtae Ty

    2016-07-01

    Diffusion properties of tissue are often expressed on the basis of directional variance, i.e., diffusion tensor imaging. In comparison, common perfusion-weighted imaging such as arterial spin labeling yields perfusion in a scalar quantity. The purpose of this study was to test the feasibility of mapping cerebral blood flow directionality using alternate ascending/descending directional navigation (ALADDIN), a recently-developed arterial spin labeling technique with sensitivity to blood flow directions. ALADDIN was applied along 3 orthogonal directions to assess directional blood flow in a vector form and also along 6 equally-spaced directions to extract blood flow tensor matrix (P) based on a blood flow ellipsoid model. Tensor elements (eigenvalues, eigenvectors, etc) were calculated to investigate characteristics of the blood flow tensor, in comparison with time-of-flight MR angiogram. While the directions of the main eigenvectors were heterogeneous throughout the brain, regional clusters of blood flow directionality were reproducible across subjects. The technique could show heterogeneous blood flow directionality within and around brain tumor, which was different from that of the contralateral normal side. The proposed method is deemed to provide information of blood flow directionality, which has not been demonstrated before. The results warrant further studies to assess changes in the directionality map as a function of scan parameters, to understand the signal sources, to investigate the possibility of mapping local blood perfusion directionality, and to evaluate its usefulness for clinical diagnosis.

  16. Cerebral blood flow simulations in realistic geometries

    Directory of Open Access Journals (Sweden)

    Szopos Marcela

    2012-04-01

    Full Text Available The aim of this work is to perform the computation of the blood flow in all the cerebral network, obtained from medical images as angiographies. We use free finite elements codes as FreeFEM++. We first test the code on analytical solutions in simplified geometries. Then, we study the influence of boundary conditions on the flow and we finally perform first computations on realistic meshes. L’objectif est ici de simuler l’écoulement sanguin dans tout le réseau cérébral (artériel et veineux obtenu à partir d’angiographies cérébrales 3D à l’aide de logiciels d’éléments finis libres, comme FreeFEM++. Nous menons d’abord une étude détaillée des résultats sur des solutions analytiques et l’influence des conditions limites à imposer dans des géométries simplifiées avant de travailler sur les maillages réalistes.

  17. Timing and topography of cerebral blood flow, aura, and headache during migraine attacks

    DEFF Research Database (Denmark)

    Olesen, J; Friberg, L; Olsen, T S

    1990-01-01

    and statistically significant spatial relations. The first observable event was a decrease of regional cerebral blood flow posteriorly in one cerebral hemisphere. Further development of this pathological process was accompanied by the aura symptoms. Thereafter headache occurred while regional cerebral blood flow...... remained decreased. During the headache phase, regional cerebral blood flow gradually changed from abnormally low to abnormally high without apparent change in headache. In some patients headache disappeared while regional cerebral blood flow remained increased. Although regional cerebral blood flow...... reduction and aura symptoms in the great majority of patients were unilateral, one-third had bilateral headache. Unilateral headache usually localized to the side on which regional cerebral blood flow was reduced and from which the aura symptoms originated (i.e., aura symptoms were perceived to occur...

  18. The effect of hyperosmotic solutions on the hepatic blood flow

    DEFF Research Database (Denmark)

    Winkler, K; Henriksen, Jens Henrik Sahl; Tygstrup, N

    1993-01-01

    The present study was undertaken in order to measure the effect of hyperosmotic solutions on portal and hepatic blood flow. In five anaesthetized pigs without arterial blood supply to the liver, portal blood flow rate was measured (electromagnetic flowmeter) during 5 min lasting intravenous infus...... for these osmotic effects are not known, but they have to be taken into consideration in studies of the portal and hepatic blood flow.......The present study was undertaken in order to measure the effect of hyperosmotic solutions on portal and hepatic blood flow. In five anaesthetized pigs without arterial blood supply to the liver, portal blood flow rate was measured (electromagnetic flowmeter) during 5 min lasting intravenous...

  19. Occlusion-free Blood Flow Animation with Wall Thickness Visualization.

    Science.gov (United States)

    Lawonn, Kai; Glaßer, Sylvia; Vilanova, Anna; Preim, Bernhard; Isenberg, Tobias

    2016-01-01

    We present the first visualization tool that combines pathlines from blood flow and wall thickness information. Our method uses illustrative techniques to provide occlusion-free visualization of the flow. We thus offer medical researchers an effective visual analysis tool for aneurysm treatment risk assessment. Such aneurysms bear a high risk of rupture and significant treatment-related risks. Therefore, to get a fully informed decision it is essential to both investigate the vessel morphology and the hemodynamic data. Ongoing research emphasizes the importance of analyzing the wall thickness in risk assessment. Our combination of blood flow visualization and wall thickness representation is a significant improvement for the exploration and analysis of aneurysms. As all presented information is spatially intertwined, occlusion problems occur. We solve these occlusion problems by dynamic cutaway surfaces. We combine this approach with a glyph-based blood flow representation and a visual mapping of wall thickness onto the vessel surface. We developed a GPU-based implementation of our visualizations which facilitates wall thickness analysis through real-time rendering and flexible interactive data exploration mechanisms. We designed our techniques in collaboration with domain experts, and we provide details about the evaluation of the technique and tool.

  20. 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.

  1. High blood sugar - self-care

    Science.gov (United States)

    ... High blood glucose - self care; Diabetes - high blood sugar ... Symptoms of high blood sugar can include: Being very thirsty or having a dry mouth Having blurry vision Having dry skin Feeling weak or tired ...

  2. Anxiety: A Cause of High Blood Pressure?

    Science.gov (United States)

    ... Conditions High blood pressure (hypertension) Can anxiety cause high blood pressure? Answers from Sheldon G. Sheps, M.D. Anxiety doesn't cause long-term high blood pressure (hypertension). But episodes of anxiety can cause dramatic, ...

  3. High Blood Pressure Often Undiagnosed, Untreated

    Science.gov (United States)

    ... page: https://medlineplus.gov/news/fullstory_162996.html High Blood Pressure Often Undiagnosed, Untreated Half of mobile clinic patients ... that's often referred to as a "silent killer" -- high blood pressure, a new Canadian study reveals. High blood pressure, ...

  4. 钙激活性氯离子通道与高肺血流性肺动脉高压%Ca2+-activated Cl- channels and pulmonary hypertension induced by high pulmonary blood flow

    Institute of Scientific and Technical Information of China (English)

    陈传斯; 庞玉生

    2012-01-01

    Pulmonary hypertension induced by high pulmonary blood flow involves a variety of complex mecha -nisms, including endothelial damage , pulmonary artery smooth muscle relaxation - contraction disorder and vascular remod -eling. Besides, the factor of ion channels in pulmonary artery smooth muscle cells is also highly correlated to vasoconstric -tion. In recent years , many studies have shown that activation of Ca - activated Cl channels is responsible for the membrane depolarization of pulmonary artery smooth muscle cells , and plays an important role in the regulation of vascular tone and vasoconstriction. This article reviews the biophysical and pharmacological characteristics of Ca - activated Cl channels as well as the influence of Ca - activated Cl channels in high pulmonary blood flow - induced pulmonary hyperten -sion.

  5. Dogs with hearth diseases causing turbulent high-velocity blood flow have changes in patelet function and von Willebrand factor multimer distribution

    DEFF Research Database (Denmark)

    Tarnow, Inge; Kristensen, Annemarie Thuri; Olsen, Lisbeth Høier

    2005-01-01

    and echocardiography were performed in all dogs. PFA100 closure times (the ability of platelets to occlude a hole in a membrane at high shear rates), platelet activation markers (plasma thromboxane B2 concentration, platelet surface P-selectin expression), platelet aggregation (in whole blood and platelet-rich plasma...

  6. Dynamic Effect of Rolling Massage on Blood Flow

    Science.gov (United States)

    Chen, Yan-Yan; Yi, Hou-Hui; Li, Hua-Bing; Fang, Hai-Ping

    2009-02-01

    The Chinese traditional medical massage has been used as a natural therapy to eliminate some diseases. Here, the effect of the rolling massage frequency to the blood flow in the blood vessels under the rolling massage manipulation is studied by the lattice Boltzmann simulation. The simulation results show that when the frequency is smaller than or comparable to the pulsatile frequency of the blood flow, the effect on the blood flux by the rolling massage is small. On the contrast, if the frequency is twice or more times of the pulsatile frequency of the blood flow, the blood flux is greatly enhanced and increases linearly with respect to the frequency. Similar behavior has also been observed on the shear stress on the blood vessel walls. The result is helpful for understanding that the rolling massage has the function of promoting the blood circulation and removing the blood stasis.

  7. Dynamic Effect of Rolling Massage on Blood Flow

    Institute of Scientific and Technical Information of China (English)

    CHEN Yan-Yan; YI Hou-Hui; LI Hua-Bing; FANG Hai-Ping

    2009-01-01

    The Chinese traditional medical massage has been used as a natural therapy to eliminate some diseases.Here, the effect of the rolling massage frequency to the blood flow in the blood vessels under the rolling massage manipulation is studied by the lattice Boltzmann simulation.The simulation results show that when the frequency is smaller than or comparable to the putsatile frequency of the blood flow, the effect on the blood flux by the rolling massage is small.On the contrast, if the frequency is twice or more times of the putsatile frequency of the blood flow, the blood flux is greatly enhanced and increases linearly with respect to the frequency.Similar behavior has also been observed on the shear stress on the blood vessel waits.The result is helpful for understanding that the rolling massage has the function of promoting the blood circulation and removing the blood stasis.

  8. Vital Signs - High Blood Pressure

    Centers for Disease Control (CDC) Podcasts

    2012-10-02

    In the U.S., nearly one third of the adult population have high blood pressure, the leading risk factor for heart disease and stroke - two of the nation's leading causes of death.  Created: 10/2/2012 by National Center for Chronic Disease Prevention and Health Promotion (NCCDPHP).   Date Released: 10/17/2012.

  9. Diagnosis of High Blood Pressure

    Medline Plus

    Full Text Available ... any other location. Health care providers diagnose this type of high blood pressure by reviewing readings in the office and readings taken anywhere else. Researchers believe stress, which can occur during the medical appointment, causes white coat hypertension. Rate This Content: NEXT >> Updated: ...

  10. Diagnosis of High Blood Pressure

    Medline Plus

    Full Text Available ... Explore High Blood Pressure What Is... Other Names Causes Who Is at Risk Signs & Symptoms Diagnosis Treatments Prevention Living With Clinical Trials Links Related Topics Atherosclerosis DASH Eating Plan Overweight and Obesity Smoking and Your Heart Stroke Send a link ...

  11. EFFECT OF INCREASED WHOLE-BLOOD VISCOSITY ON REGIONAL BLOOD FLOWS IN CHRONICALLY HYPOXEMIC LAMBS

    NARCIS (Netherlands)

    DALINGHAUS, M; KNOESTER, H; GRATAMA, JWC; VANDERMEER, J; ZIJLSTRA, WG; KUIPERS, JRG

    1994-01-01

    In chronic hypoxemia blood flow and oxygen supply to vital organs are maintained, but to nonvital organs they are decreased. We measured organ blood flows (microspheres) and whole blood viscosity in 10 chronically hypoxemic lambs, with an atrial septal defect and pulmonary stenosis, and in 8 control

  12. Daily rhythm of cerebral blood flow velocity

    Directory of Open Access Journals (Sweden)

    Spielman Arthur J

    2005-03-01

    Full Text Available Abstract Background CBFV (cerebral blood flow velocity is lower in the morning than in the afternoon and evening. Two hypotheses have been proposed to explain the time of day changes in CBFV: 1 CBFV changes are due to sleep-associated processes or 2 time of day changes in CBFV are due to an endogenous circadian rhythm independent of sleep. The aim of this study was to examine CBFV over 30 hours of sustained wakefulness to determine whether CBFV exhibits fluctuations associated with time of day. Methods Eleven subjects underwent a modified constant routine protocol. CBFV from the middle cerebral artery was monitored by chronic recording of Transcranial Doppler (TCD ultrasonography. Other variables included core body temperature (CBT, end-tidal carbon dioxide (EtCO2, blood pressure, and heart rate. Salivary dim light melatonin onset (DLMO served as a measure of endogenous circadian phase position. Results A non-linear multiple regression, cosine fit analysis revealed that both the CBT and CBFV rhythm fit a 24 hour rhythm (R2 = 0.62 and R2 = 0.68, respectively. Circadian phase position of CBT occurred at 6:05 am while CBFV occurred at 12:02 pm, revealing a six hour, or 90 degree difference between these two rhythms (t = 4.9, df = 10, p Conclusion In conclusion, time of day variations in CBFV have an approximately 24 hour rhythm under constant conditions, suggesting regulation by a circadian oscillator. The 90 degree-phase angle difference between the CBT and CBFV rhythms may help explain previous findings of lower CBFV values in the morning. The phase difference occurs at a time period during which cognitive performance decrements have been observed and when both cardiovascular and cerebrovascular events occur more frequently. The mechanisms underlying this phase angle difference require further exploration.

  13. Data adaptive estimation of transversal blood flow velocities

    DEFF Research Database (Denmark)

    Pirnia, E.; Jakobsson, A.; Gudmundson, E.

    2014-01-01

    The examination of blood flow inside the body may yield important information about vascular anomalies, such as possible indications of, for example, stenosis. Current Medical ultrasound systems suffer from only allowing for measuring the blood flow velocity along the direction of irradiation......, posing natural difficulties due to the complex behaviour of blood flow, and due to the natural orientation of most blood vessels. Recently, a transversal modulation scheme was introduced to induce also an oscillation along the transversal direction, thereby allowing for the measurement of also...... the transversal blood flow. In this paper, we propose a novel data-adaptive blood flow estimator exploiting this modulation scheme. Using realistic Field II simulations, the proposed estimator is shown to achieve a notable performance improvement as compared to current state-of-the-art techniques....

  14. Prediction of Anomalous Blood Viscosity in Confined Shear Flow

    Science.gov (United States)

    Thiébaud, Marine; Shen, Zaiyi; Harting, Jens; Misbah, Chaouqi

    2014-06-01

    Red blood cells play a major role in body metabolism by supplying oxygen from the microvasculature to different organs and tissues. Understanding blood flow properties in microcirculation is an essential step towards elucidating fundamental and practical issues. Numerical simulations of a blood model under a confined linear shear flow reveal that confinement markedly modifies the properties of blood flow. A nontrivial spatiotemporal organization of blood elements is shown to trigger hitherto unrevealed flow properties regarding the viscosity η, namely ample oscillations of its normalized value [η]=(η-η0)/(η0ϕ) as a function of hematocrit ϕ (η0=solvent viscosity). A scaling law for the viscosity as a function of hematocrit and confinement is proposed. This finding can contribute to the conception of new strategies to efficiently detect blood disorders, via in vitro diagnosis based on confined blood rheology. It also constitutes a contribution for a fundamental understanding of rheology of confined complex fluids.

  15. Cerebellar blood flow in methylmercury poisoning (Minamata disease)

    Energy Technology Data Exchange (ETDEWEB)

    Itoh, K.; Korogi, Y.; Tomiguchi, S.; Takahashi, M. [Dept. of Radiology, Kumamoto University School of Medicine (Japan); Okajima, T. [Dept. of Neurology, Johnan Hospital, Maihara, Johnan-mochi (Japan); Sato, H. [Dept. of Neurology, Minamata City General Hospital and Medical Centre (Japan)

    2001-04-01

    We looked at regional cerebellar blood flow in patients with Minamata disease (MD) using technetium-99 m ethyl cysteinate dimer (99m-Tc-ECD). We carried out single-photon emission computed tomography (SPECT) on 15 patients with MD (eight men, seven women, aged 51-78 years, mean 70.5 years) and 11 control subjects (eight men, three women, aged 62-80 years, mean 72.5 years). Regional blood flow was measured in the superior, middle, and inferior portions of the cerebellar hemispheres, and the frontal, temporal and occipital cerebral lobes. The degree of cerebellar atrophy was assessed on MRI. There were significant differences in regional blood flow in all parts of the cerebellum between patients and control, but no significant decrease was observed in the cerebrum. Blood flow was lower in the inferior cerebellum than in the other parts. Even in patients without cerebellar atrophy, flow was significantly decreased regional blood flow in the inferior part. (orig.)

  16. Cerebellar blood flow in methylmercury poisoning (Minamata disease).

    Science.gov (United States)

    Itoh, K; Korogi, Y; Tomiguchi, S; Takahashi, M; Okajima, T; Sato, H

    2001-04-01

    We looked at regional cerebellar blood flow in patients with Minamata disease (MD) using technetium-99m ethyl cysteinate dimer (99m-Tc-ECD). We carried out single-photon emission computed tomography (SPECT) on 15 patients with MD (eight men, seven women, aged 51-78 years, mean 70.5 years) and 11 control subjects (eight men, three women, aged 62-80 years, mean 72.5 years). Regional blood flow was measured in the superior, middle, and inferior portions of the cerebellar hemispheres, and the frontal, temporal and occipital cerebral lobes. The degree of cerebellar atrophy was assessed on MRI. There were significant differences in regional blood flow in all parts of the cerebellum between patients and control, but no significant decrease was observed in the cerebrum. Blood flow was lower in the inferior cerebellum than in the other parts. Even in patients without cerebellar atrophy, flow was significantly decreased regional blood flow in the inferior part.

  17. High blood pressure and eye disease

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/000999.htm High blood pressure and eye disease To use the sharing features on this page, please enable JavaScript. High blood pressure can damage blood vessels in the retina . The ...

  18. Vascular Function and Regulation of Blood Flow in Resting and Contracting Skeletal Muscle

    DEFF Research Database (Denmark)

    Nyberg, Michael Permin

    in the regulation of exercise hyperemia. Furthermore, blood flow to contracting leg skeletal muscles is reduced both in essential hypertension and with aging. The potential difference in vasoactive system(s) responsible for the reduction in blood flow in the two conditions is in agreement with the suggestion......The precise matching of blood flow, oxygen delivery and metabolism is essential as it ensures that any increase in muscle work is precisely matched by increases in oxygen delivery. Therefore, understanding the control mechanisms of skeletal muscle blood flow regulation is of great biological...... importance. The present work provides new insight in to vasodilator interactions important for exercise hyperemia and sheds light on mechanisms important for vascular function and regulation of skeletal muscle blood flow in essential hypertension (high blood pressure) and aging and identifies mechanisms...

  19. Synthetic Capillaries to Control Microscopic Blood Flow

    Science.gov (United States)

    Sarveswaran, K.; Kurz, V.; Dong, Z.; Tanaka, T.; Penny, S.; Timp, G.

    2016-02-01

    Capillaries pervade human physiology. The mean intercapillary distance is only about 100 μm in human tissue, which indicates the extent of nutrient diffusion. In engineered tissue the lack of capillaries, along with the associated perfusion, is problematic because it leads to hypoxic stress and necrosis. However, a capillary is not easy to engineer due to its complex cytoarchitecture. Here, it is shown that it is possible to create in vitro, in about 30 min, a tubular microenvironment with an elastic modulus and porosity consistent with human tissue that functionally mimicks a bona fide capillary using “live cell lithography”(LCL) to control the type and position of cells on a composite hydrogel scaffold. Furthermore, it is established that these constructs support the forces associated with blood flow, and produce nutrient gradients similar to those measured in vivo. With LCL, capillaries can be constructed with single cell precision—no other method for tissue engineering offers such precision. Since the time required for assembly scales with the number of cells, this method is likely to be adapted first to create minimal functional units of human tissue that constitute organs, consisting of a heterogeneous population of 100–1000 cells, organized hierarchically to express a predictable function.

  20. 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 tubula...

  1. Glial and neuronal control of brain blood flow

    DEFF Research Database (Denmark)

    Attwell, David; Buchan, Alastair M; Charpak, Serge

    2010-01-01

    Blood flow in the brain is regulated by neurons and astrocytes. Knowledge of how these cells control blood flow is crucial for understanding how neural computation is powered, for interpreting functional imaging scans of brains, and for developing treatments for neurological disorders. It is now...

  2. Blood flow velocity in migraine attacks - a transcranial Doppler study

    Energy Technology Data Exchange (ETDEWEB)

    Zwetsloot, C.P.; Caekebeke, J.F.V.; Jansen, J.C.; Odink, J.; Ferrari, M.D. (Rijksuniversiteit Leiden (Netherlands))

    1991-05-01

    A pulsed Doppler device was used to measure blood flow velocities in the common carotid artery, the extracranial part of the internal carotid artery, the external carotid artery, the middle cerebral artery, and the anterior cerebral artery in 31 migraneurs without aura (n=27) and with aura (n=4), both during and ouside an attack. The aims were to compare blood flow velocity during and between migraine attacks and to study asymmetries of the blood flow velocity. Compared with blood flow velocity values obtained in the attack-free interval, blood flow velocity was lower during attacks without aura in both common carotid arteries, but not in the other extra- and intracranial vessels which were examined. However, during attacks of migraine with aura, blood flow velocity tended to be lower in all examined vessels. There were no asymmetries of the blood flow velocity. It is suggested that during migraine attacks without aura there is a dissociation in blood flow regulation in the common carotid and middle cerebral arteries. 20 refs., 2 tabs.

  3. Sex differences of human cortical blood flow and energy metabolism

    DEFF Research Database (Denmark)

    Aanerud, Joel; Borghammer, Per; Rodell, Anders

    2017-01-01

    cortex. Women had significant decreases of cerebral blood flow as function of age in frontal and parietal lobes. Young women had significantly higher cerebral blood flow than men in frontal and temporal lobes, but these differences had disappeared at age 65. The absent sex difference of cerebral energy...

  4. Regional cerebral blood flow in focal cortical epilepsy

    DEFF Research Database (Denmark)

    Hougaard, Kristina Dupont; Oikawa, T; Sveinsdottir, E

    1976-01-01

    Regional cerebral blood flow (rCBF) was studied in ten patients with focal cortical epilepsy. The blood flow was measured by the intra-arterial injection of xenon 133 (133Xe), and the isotope clearance was recorded by a multidetector scintillation camera with 254 detectors. Three patients were st...

  5. Subcutaneous blood flow during insulin-induced hypoglycaemia

    DEFF Research Database (Denmark)

    Hilsted, J; Madsbad, S; Sestoft, L

    1982-01-01

    Subcutaneous blood flow was measured preceding insulin-induced hypoglycaemia, at the onset of hypoglycaemic symptoms and 2 h later in juvenile diabetics with and without autonomic neuropathy and in normal males. In all groups subcutaneous blood flow decreased at the onset of hypoglycaemic symptoms...

  6. 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.

  7. Questions and Answers about High Blood Pressure

    Science.gov (United States)

    ... checked out by a doctor. Am I at risk for high blood pressure? Anyone can develop high blood pressure. But there are several factors that increase your risk: Being overweight or obese Not ... if I have high blood pressure? High blood pressure is often called "the silent ...

  8. High Blood Pressure (Hypertension) (For Parents)

    Science.gov (United States)

    ... Old Feeding Your 1- to 2-Year-Old High Blood Pressure (Hypertension) KidsHealth > For Parents > High Blood Pressure (Hypertension) A ... posture, and medications. continue Long-Term Effects of High Blood Pressure When someone has high blood pressure, the heart ...

  9. High Blood Pressure (Hypertension) (For Parents)

    Science.gov (United States)

    ... Old Feeding Your 1- to 2-Year-Old High Blood Pressure (Hypertension) KidsHealth > For Parents > High Blood Pressure (Hypertension) ... posture, and medications. continue Long-Term Effects of High Blood Pressure When someone has high blood pressure, the heart ...

  10. Lattice BGK Simulations of the Blood Flow in Elastic Vessels

    Institute of Scientific and Technical Information of China (English)

    LU Xiao-Yang; YI Hou-Hui; CHEN Ji-Yao; FANG Hai-Ping

    2006-01-01

    @@ The lattice Boltzmann method is applied to study the flow in elastic blood vessels. The volume-flow rate increases considerably when the compliance constant of the blood vessel is below a critical value. There is a region of the compliance constant in which the average volume-flow rate is dramatically enhanced. A harmonic perturbation of the pressure does not change the behaviour of the average volume-flow rate while the harmonic wave attenuates very quickly along the tube when the resonant period is close to that of the input wave. The model, together with the simulation results, is expected to be helpful to understand the mechanism of the blood volume-flow rate related to the compliance constant of the blood vessel, especially on the dependence of the flux of human blood vessel under weather changes, which has medical significance.

  11. Blood flow controls bone vascular function and osteogenesis

    Science.gov (United States)

    Ramasamy, Saravana K.; Kusumbe, Anjali P.; Schiller, Maria; Zeuschner, Dagmar; Bixel, M. Gabriele; Milia, Carlo; Gamrekelashvili, Jaba; Limbourg, Anne; Medvinsky, Alexander; Santoro, Massimo M.; Limbourg, Florian P.; Adams, Ralf H.

    2016-01-01

    While blood vessels play important roles in bone homeostasis and repair, fundamental aspects of vascular function in the skeletal system remain poorly understood. Here we show that the long bone vasculature generates a peculiar flow pattern, which is important for proper angiogenesis. Intravital imaging reveals that vessel growth in murine long bone involves the extension and anastomotic fusion of endothelial buds. Impaired blood flow leads to defective angiogenesis and osteogenesis, and downregulation of Notch signalling in endothelial cells. In aged mice, skeletal blood flow and endothelial Notch activity are also reduced leading to decreased angiogenesis and osteogenesis, which is reverted by genetic reactivation of Notch. Blood flow and angiogenesis in aged mice are also enhanced on administration of bisphosphonate, a class of drugs frequently used for the treatment of osteoporosis. We propose that blood flow and endothelial Notch signalling are key factors controlling ageing processes in the skeletal system. PMID:27922003

  12. Mammary blood flow regulation in the nursing rabbit

    Energy Technology Data Exchange (ETDEWEB)

    Katz, M.; Creasy, R.K.

    1984-11-01

    Cardiac output and mammary blood flow distribution prior to and after suckling were studied in 10 nursing rabbits by means of radionuclide-labeled microspheres. Suckling was followed by a 5.8% rise in cardiac output and a 20.4% rise in mammary blood flow. Determinations of intraglandular blood flow distribution have shown that there was a 43% increase in blood flow to the glands suckled from as compared to a 22.7% rise to the contralateral untouched glands and a 4.9% rise in the remainder of untouched glands. The conclusion is that a local mechanism may be involved in the regulation of mammary blood flow in the nursing rabbit.

  13. Uncertainty quantification in coronary blood flow simulations: Impact of geometry, boundary conditions and blood viscosity.

    Science.gov (United States)

    Sankaran, Sethuraman; Kim, Hyun Jin; Choi, Gilwoo; Taylor, Charles A

    2016-08-16

    Computational fluid dynamic methods are currently being used clinically to simulate blood flow and pressure and predict the functional significance of atherosclerotic lesions in patient-specific models of the coronary arteries extracted from noninvasive coronary computed tomography angiography (cCTA) data. One such technology, FFRCT, or noninvasive fractional flow reserve derived from CT data, has demonstrated high diagnostic accuracy as compared to invasively measured fractional flow reserve (FFR) obtained with a pressure wire inserted in the coronary arteries during diagnostic cardiac catheterization. However, uncertainties in modeling as well as measurement results in differences between these predicted and measured hemodynamic indices. Uncertainty in modeling can manifest in two forms - anatomic uncertainty resulting in error of the reconstructed 3D model and physiologic uncertainty resulting in errors in boundary conditions or blood viscosity. We present a data-driven framework for modeling these uncertainties and study their impact on blood flow simulations. The incompressible Navier-Stokes equations are used to model blood flow and an adaptive stochastic collocation method is used to model uncertainty propagation in the Navier-Stokes equations. We perform uncertainty quantification in two geometries, an idealized stenosis model and a patient specific model. We show that uncertainty in minimum lumen diameter (MLD) has the largest impact on hemodynamic simulations, followed by boundary resistance, viscosity and lesion length. We show that near the diagnostic cutoff (FFRCT=0.8), the uncertainty due to the latter three variables are lower than measurement uncertainty, while the uncertainty due to MLD is only slightly higher than measurement uncertainty. We also show that uncertainties are not additive but only slightly higher than the highest single parameter uncertainty. The method presented here can be used to output interval estimates of hemodynamic indices

  14. Ultrasonic Doppler measurement of renal artery blood flow

    Science.gov (United States)

    Freund, W. R.; Beaver, W. L.; Meindl, J. D.

    1976-01-01

    Studies were made of (1) blood flow redistribution during lower body negative pressure (LBNP), (2) the profile of blood flow across the mitral annulus of the heart (both perpendicular and parallel to the commissures), (3) testing and evaluation of a number of pulsed Doppler systems, (4) acute calibration of perivascular Doppler transducers, (5) redesign of the mitral flow transducers to improve reliability and ease of construction, and (6) a frequency offset generator designed for use in distinguishing forward and reverse components of blood flow by producing frequencies above and below the offset frequency. Finally methodology was developed and initial results were obtained from a computer analysis of time-varying Doppler spectra.

  15. Quantification of complex blood flow using real-time in vivo vector flow ultrasound

    DEFF Research Database (Denmark)

    Pedersen, Mads Møller; Pihl, Michael Johannes; Haugaard, Per;

    2010-01-01

    A quantitative method for distinguishing complex from non-complex flow patterns in ultrasound is presented. A new commercial BK Medical ultrasound scanner uses the Transverse Oscillation vector flow technique for visualising flow patterns in real-time. In vivo vector flow data of the blood flow...

  16. Cerebral blood flow and metabolism during sleep.

    Science.gov (United States)

    Madsen, P L; Vorstrup, S

    1991-01-01

    A review of the current literature regarding sleep-induced changes in cerebral blood flow (CBF) and cerebral metabolic rate (CMR) is presented. Early investigations have led to the notion that dreamless sleep was characterized by global values of CBF and CMR practically at the level of wakefulness, while rapid eye movement (REM) sleep (dream sleep) was a state characterized by a dramatically increased level of CBF and possibly also of CMR. However, recent investigations firmly contradict this notion. Investigations on CBF and CMR performed during non-REM sleep, taking the effect of different levels of sleep into consideration, show that light sleep (stage II) is characterized by global levels of CBF and CMR only slightly reduced by 3-10% below the level associated with wakefulness, whereas CBF and CMR during deep sleep (stage III-IV) is dramatically reduced by 25-44%. Furthermore, recent data indicate that global levels of CBF and CMR are about the same during REM sleep as in wakefulness. On the regional level, deep sleep seems to be associated with a uniform decrease in regional CBF and CMR. Investigations concerning regional CBF and CMR during REM sleep are few but data from recent investigations seem to identify site-specific changes in regional CBF and CMR during REM sleep. CBF and CMR are reflections of cerebral synaptic activity and the magnitude of reduction in these variables associated with deep sleep indicates that overall cerebral synaptic activity is reduced to approximately one-half the level associated with wakefulness, while cerebral synaptic activity levels during REM sleep are similar to wakefulness. However, even though the new understanding of CBF and CMR during sleep provides significant and important information of the brain's mode of working during sleep, it does not at its current state identify the physiological processes involved in sleep or the physiological role of sleep.

  17. In vivo analysis of physiological 3D blood flow of cerebral veins

    Energy Technology Data Exchange (ETDEWEB)

    Schuchardt, Florian; Schroeder, Laure; Baeuerle, Jochen; Harloff, Andreas [University Medical Centre, Department of Neurology, Freiburg (Germany); Anastasopoulos, Constantin [University Medical Center, Department of Neuropaediatrics and Muscle Disorders, Freiburg (Germany); University Medical Centre, Department of Neuroradiology, Freiburg (Germany); Markl, Michael [Northwestern University, Department of Radiology, Feinberg School of Medicine and McCormick School of Engineering, Chicago, IL (United States); Hennemuth, Anja; Drexl, Johann [Fraunhofer MEVIS, Bremen (Germany); Valdueza, Jose M. [Neurological Center, Segeberger Kliniken, Bad Segeberg (Germany); Mader, Irina [University Medical Centre, Department of Neuroradiology, Freiburg (Germany)

    2015-08-15

    To visualize and quantify physiological blood flow of intracranial veins in vivo using time-resolved, 3D phase-contrast MRI (4D flow MRI), and to test measurement accuracy. Fifteen healthy volunteers underwent repeated ECG-triggered 4D flow MRI (3 Tesla, 32-channel head coil). Intracranial venous blood flow was analysed using dedicated software allowing for blood flow visualization and quantification in analysis planes at the superior sagittal, straight, and transverse sinuses. MRI was evaluated for intra- and inter-observer agreement and scan-rescan reproducibility. Measurements of the transverse sinuses were compared with transcranial two-dimensional duplex ultrasound. Visualization of 3D blood flow within cerebral sinuses was feasible in 100 % and within at least one deep cerebral vein in 87 % of the volunteers. Blood flow velocity/volume increased along the superior sagittal sinus and was lower in the left compared to the right transverse sinus. Intra- and inter-observer reliability and reproducibility of blood flow velocity (mean difference 0.01/0.02/0.02 m/s) and volume (mean difference 0.0002/-0.0003/0.00003 l/s) were good to excellent. High/low velocities were more pronounced (8 % overestimation/9 % underestimation) in MRI compared to ultrasound. Four-dimensional flow MRI reliably visualizes and quantifies three-dimensional cerebral venous blood flow in vivo and is promising for studies in patients with sinus thrombosis and related diseases. (orig.)

  18. Dynamics of blood flow in a microfluidic ladder network

    Science.gov (United States)

    Maddala, Jeevan; Zilberman-Rudenko, Jevgenia; McCarty, Owen

    The dynamics of a complex mixture of cells and proteins, such as blood, in perturbed shear flow remains ill-defined. Microfluidics is a promising technology for improving the understanding of blood flow under complex conditions of shear; as found in stent implants and in tortuous blood vessels. We model the fluid dynamics of blood flow in a microfluidic ladder network with dimensions mimicking venules. Interaction of blood cells was modeled using multiagent framework, where cells of different diameters were treated as spheres. This model served as the basis for predicting transition regions, collision pathways, re-circulation zones and residence times of cells dependent on their diameters and device architecture. Based on these insights from the model, we were able to predict the clot formation configurations at various locations in the device. These predictions were supported by the experiments using whole blood. To facilitate platelet aggregation, the devices were coated with fibrillar collagen and tissue factor. Blood was perfused through the microfluidic device for 9 min at a physiologically relevant venous shear rate of 600 s-1. Using fluorescent microscopy, we observed flow transitions near the channel intersections and at the areas of blood flow obstruction, which promoted larger thrombus formation. This study of integrating model predictions with experimental design, aids in defining the dynamics of blood flow in microvasculature and in development of novel biomedical devices.

  19. Regional patterns of cortical blood flow distinguish extraverts from introverts

    OpenAIRE

    Stenberg, Georg; Risberg, Jarl; Warkentin, S.; Rosén, Ingmar

    1990-01-01

    Eysenck's hypothesis of higher cortical arousal in introverts was examined using regional cerebral blood flow measurement in 37 healthy subjects . The measurement was made at rest, using the133Xe-inhalation method. Estimates of gray matter flow were obtained for 32 brain regions. There was no significant evidence of personality differences in general arousal, as measured by the mean flow level, averaged over all regions. There were, however, regional differences. An overall test of the blood ...

  20. Validation of Blood Flow Simulations in Intracranial Aneurysms

    Science.gov (United States)

    Yu, Yue; Anor, Tomer; Baek, Hyoungsu; Jayaraman, Mahesh; Madsen, Joseph; Karniadakis, George

    2010-11-01

    Catheter-based digital subtraction angiography (DSA) is the most accurate diagnostic procedure for investigating vascular anomalies and cerebral blood flow. Here we describe utilization of DSA in a patient with an intracranial aneursysm to validate corresponding spectral element simulations. Subsequently, we examine via visualization the structure of flow in internal carotid arteries laden with three different types of aneurysms: (1) a wide-necked saccular aneurysm, (2) a narrower-necked saccular aneurysm, and (3) a case with two adjacent saccular aneurysms. We have found through high resolution simulations that in cases (1) and (3) in physiological conditions a hydrodynamic instability occurs during the decelerating systolic phase resulting in a high frequency oscillation (20-50 Hz). We use the in-silico dye visualization to discriminate among different physical mechanisms causing the instability and contrast their effect with case (2) for which an instability arises only at much higher flowrates.

  1. Effects of exercise training with blood flow restriction on blood pressure in medicated hypertensive patients

    Directory of Open Access Journals (Sweden)

    Marcos Antônio Cezar

    2016-06-01

    Full Text Available Abstract The development of non-pharmacological approaches to hypertension (HA is critical for both prevention and treatment. This study examined the hemodynamic and biochemical responses of medicated hypertensive women to resistance exercise with blood flow restriction (vascular occlusion. Twenty-three women were randomly assigned to one of three groups: High intensity strength training (n = 8; low-intensity resistance exercise with occlusion (n = 8; and control (n = 7. The first two groups underwent eight weeks of training performed twice a week, including three series of wrist flexion exercises with or without vascular occlusion. The exercised with occlusion group showed pre- to post-test reduction in systolic and diastolic blood pressure, mean arterial pressure, and double product, whereas the other groups showed no significant hemodynamic changes. In conclusion, resistance exercise during 8 weeks was effective in lowering blood pressure in medicated hypertensive subjects.

  2. Dynamical Modes of Deformed Red Blood Cells and Lipid Vesicles in Flows

    Science.gov (United States)

    Noguchi, H.

    Red blood cells and lipid vesicles exhibit rich behaivor in flows.Their dynamics were studied using a particle-based hydrodynamic simulation method, multi-particle collision dynamics. Rupture of lipid vesicles in simple shear flow was simulated by meshless membrane model. Several shape transitions of lipid vesicles and red blood cells are induced by flows. Transition of a lipid vesicle from budded to prolate shapes with increasing shear rate and ordered alignments of deformed elastic vesicles in high density are presented.

  3. A model of blood flow in the mesenteric arterial system

    Directory of Open Access Journals (Sweden)

    Cheng Leo K

    2007-05-01

    Full Text Available Abstract Background There are some early clinical indicators of cardiac ischemia, most notably a change in a person's electrocardiogram. Less well understood, but potentially just as dangerous, is ischemia that develops in the gastrointestinal system. Such ischemia is difficult to diagnose without angiography (an invasive and time-consuming procedure mainly due to the highly unspecific nature of the disease. Understanding how perfusion is affected during ischemic conditions can be a useful clinical tool which can help clinicians during the diagnosis process. As a first step towards this final goal, a computational model of the gastrointestinal system has been developed and used to simulate realistic blood flow during normal conditions. Methods An anatomically and biophysically based model of the major mesenteric arteries has been developed to be used to simulate normal blood flows. The computational mesh used for the simulations has been generated using data from the Visible Human project. The 3D Navier-Stokes equations that govern flow within this mesh have been simplified to an efficient 1D scheme. This scheme, together with a constitutive pressure-radius relationship, has been solved numerically for pressure, vessel radius and velocity for the entire mesenteric arterial network. Results The computational model developed shows close agreement with physiologically realistic geometries other researchers have recorded in vivo. Using this model as a framework, results were analyzed for the four distinct phases of the cardiac cycle – diastole, isovolumic contraction, ejection and isovolumic relaxation. Profiles showing the temporally varying pressure and velocity for a periodic input varying between 10.2 kPa (77 mmHg and 14.6 kPa (110 mmHg at the abdominal aorta are presented. An analytical solution has been developed to model blood flow in tapering vessels and when compared with the numerical solution, showed excellent agreement. Conclusion An

  4. On the flow dependency of the electrical conductivity of blood

    NARCIS (Netherlands)

    Hoetink, AE; Faes, TJC; Visser, KR; Heethaar, RM

    Experiments presented in the literature show that the electrical conductivity of flowing blood depends on flow velocity. The aim of this study is to extend the Maxwell-Fricke theory, developed for a dilute suspension of ellipsoidal particles in an electrolyte, to explain this flow dependency of the

  5. On the flow dependency of the electrical conductivity of blood

    NARCIS (Netherlands)

    Hoetink, AE; Faes, TJC; Visser, KR; Heethaar, RM

    2004-01-01

    Experiments presented in the literature show that the electrical conductivity of flowing blood depends on flow velocity. The aim of this study is to extend the Maxwell-Fricke theory, developed for a dilute suspension of ellipsoidal particles in an electrolyte, to explain this flow dependency of the

  6. Dynamics of renal blood flow autoregulation in rats

    DEFF Research Database (Denmark)

    Holstein-Rathlou, N H; Wagner, A J; Marsh, D J

    1991-01-01

    Two separate components could be resolved in tests of the dynamic autoregulation of renal blood flow. The slow component corresponds to the frequency at which spontaneous proximal tubular pressure oscillations are found, and are most likely due to the operation of the TGF. The high frequency...... component most likely represents an intrinsic vascular, myogenic, mechanism. The gain maximum of the admittance in the frequency range corresponding to the autonomous tubular oscillations indicates that the dynamic characteristics responsible for the occurrence of the spontaneous tubular oscillations must...

  7. Diagnosis of High Blood Pressure

    Medline Plus

    Full Text Available ... blood pressure test is easy and painless and can be done in a health care provider’s office ... severity of your blood pressure, he or she can order additional tests to determine if your blood ...

  8. ANALYSIS OF PULSATILE BLOOD FLOW IN AXIALLY MOVING ARTERIES

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    In order to study motional properties of pulsatile blood flow in axially moving arteries, the authors derived some expressions of the pulsatile blood flow from the basic equations of motion for blood and vascular walls, including an axial blood velocity equation, a flow rate equation and a wall shear stress equation, which described not only the overall axial movement of the arteries but also the elastic properties of the vascular walls, discussed the effects of the arterial wall elasticity on the wall shear stress in coronary arteries in terms of these expressions, and analyzed changes of motional properties of pulsatile blood flow between an elastic arterial tube model and a rigid tube model. The results proved the inference by J.E. Moore Jr. et al. (1994) that the axial movement of arteries be as important in determining coronary artery hemodynamics as the elastic property of the vascular wall.

  9. The effect of hyperosmotic solutions on the hepatic blood flow

    DEFF Research Database (Denmark)

    Winkler, K; Henriksen, Jens Henrik; Tygstrup, N

    1993-01-01

    The present study was undertaken in order to measure the effect of hyperosmotic solutions on portal and hepatic blood flow. In five anaesthetized pigs without arterial blood supply to the liver, portal blood flow rate was measured (electromagnetic flowmeter) during 5 min lasting intravenous...... infusions of hyperosmotic galactose (50%, 84-100 ml) and mannitol (25%, 100 ml), with physiological saline (100 ml) as control. Portal blood flow increased to a peak value of (39% [P = 0.06] galactose and 37%, [P = 0.06], mannitol) soon after stop of the hyperosmotic infusion. For galactose the change ended...... somewhat earlier than for mannitol. Saline induced a minor increase (15%). Similarly, increments of, on average, 144% of the hepatic blood flow rate was seen in six patients with cirrhosis, following infusion of hyperosmotic galactose, the increase being more pronounced than in the pigs. The causes...

  10. Tracking flow of leukocytes in blood for drug analysis

    Science.gov (United States)

    Basharat, Arslan; Turner, Wesley; Stephens, Gillian; Badillo, Benjamin; Lumpkin, Rick; Andre, Patrick; Perera, Amitha

    2011-03-01

    Modern microscopy techniques allow imaging of circulating blood components under vascular flow conditions. The resulting video sequences provide unique insights into the behavior of blood cells within the vasculature and can be used as a method to monitor and quantitate the recruitment of inflammatory cells at sites of vascular injury/ inflammation and potentially serve as a pharmacodynamic biomarker, helping screen new therapies and individualize dose and combinations of drugs. However, manual analysis of these video sequences is intractable, requiring hours per 400 second video clip. In this paper, we present an automated technique to analyze the behavior and recruitment of human leukocytes in whole blood under physiological conditions of shear through a simple multi-channel fluorescence microscope in real-time. This technique detects and tracks the recruitment of leukocytes to a bioactive surface coated on a flow chamber. Rolling cells (cells which partially bind to the bioactive matrix) are detected counted, and have their velocity measured and graphed. The challenges here include: high cell density, appearance similarity, and low (1Hz) frame rate. Our approach performs frame differencing based motion segmentation, track initialization and online tracking of individual leukocytes.

  11. Adrenergically stimulated blood flow in brown adipose tissue is not dependent on thermogenesis.

    Science.gov (United States)

    Abreu-Vieira, Gustavo; Hagberg, Carolina E; Spalding, Kirsty L; Cannon, Barbara; Nedergaard, Jan

    2015-05-01

    Brown adipose tissue (BAT) thermogenesis relies on blood flow to be supplied with nutrients and oxygen and for the distribution of the generated heat to the rest of the body. Therefore, it is fundamental to understand the mechanisms by which blood flow is regulated and its relation to thermogenesis. Here, we present high-resolution laser-Doppler imaging (HR-LDR) as a novel method for noninvasive in vivo measurement of BAT blood flow in mice. Using HR-LDR, we found that norepinephrine stimulation increases BAT blood flow in a dose-dependent manner and that this response is profoundly modulated by environmental temperature acclimation. Surprisingly, we found that mice lacking uncoupling protein 1 (UCP1) have fully preserved BAT blood flow response to norepinephrine despite failing to perform thermogenesis. BAT blood flow was not directly correlated to systemic glycemia, but glucose injections could transiently increase tissue perfusion. Inguinal white adipose tissue, also known as a brite/beige adipose tissue, was also sensitive to cold acclimation and similarly increased blood flow in response to norepinephrine. In conclusion, using a novel noninvasive method to detect BAT perfusion, we demonstrate that adrenergically stimulated BAT blood flow is qualitatively and quantitatively fully independent of thermogenesis, and therefore, it is not a reliable parameter for the estimation of BAT activation and heat generation.

  12. Effects of non Newtonian spiral blood flow through arterial stenosis

    Science.gov (United States)

    Hasan, Md. Mahmudul; Maruf, Mahbub Alam; Ali, Mohammad

    2016-07-01

    The spiral component of blood flow has both beneficial and detrimental effects in human circulatory system. A numerical investigation is carried out to analyze the effect of spiral blood flow through an axisymmetric three dimensional artery having 75% stenosis at the center. Blood is assumed as a Non-Newtonian fluid. Standard k-ω model is used for the simulation with the Reynolds number of 1000. A parabolic velocity profile with spiral flow is used as inlet boundary condition. The peak values of all velocity components are found just after stenosis. But total pressure gradually decreases at downstream. Spiral flow of blood has significant effects on tangential component of velocity. However, the effect is mild for radial and axial velocity components. The peak value of wall shear stress is at the stenosis zone and decreases rapidly in downstream. The effect of spiral flow is significant for turbulent kinetic energy. Detailed investigation and relevant pathological issues are delineated throughout the paper.

  13. Mesenteric, coeliac and splanchnic blood flow in humans during exercise

    DEFF Research Database (Denmark)

    Perko, M J; Nielsen, H B; Skak, C

    1998-01-01

    blood flow as assessed by the Indocyanine Green dye-elimination technique. 3. Cycling increased arterial pressure, heart rate and cardiac output, while it reduced total vascular resistance. These responses were not altered in the postprandial state. During fasting, cycling increased mesenteric, coeliac......1. Exercise reduces splanchnic blood flow, but the mesenteric contribution to this response is uncertain. 2. In nineteen humans, superior mesenteric and coeliac artery flows were determined by duplex ultrasonography during fasting and postprandial submaximal cycling and compared with the splanchnic...... decreased by 51 and 31 % (0.49 +/- 0.07 and 0.96 +/- 0.28 l min-1). Splanchnic blood flow values assessed by duplex ultrasound and by dye-elimination techniques were correlated (r = 0.70; P exercise in humans, splanchnic resistance increases and blood flow is reduced following...

  14. Mesenteric, coeliac and splanchnic blood flow in humans during exercise

    DEFF Research Database (Denmark)

    Perko, M J; Nielsen, H B; Skak, C;

    1998-01-01

    1. Exercise reduces splanchnic blood flow, but the mesenteric contribution to this response is uncertain. 2. In nineteen humans, superior mesenteric and coeliac artery flows were determined by duplex ultrasonography during fasting and postprandial submaximal cycling and compared with the splanchnic...... blood flow as assessed by the Indocyanine Green dye-elimination technique. 3. Cycling increased arterial pressure, heart rate and cardiac output, while it reduced total vascular resistance. These responses were not altered in the postprandial state. During fasting, cycling increased mesenteric, coeliac...... and splanchnic resistances by 76, 165 and 126 %, respectively, and it reduced corresponding blood flows by 32, 50 and 43 % (by 0.18 +/- 0.04, 0.42 +/- 0.03 and 0.60 +/- 0.04 l min-1). Postprandially, mesenteric and splanchnic vascular resistances decreased, thereby elevating regional blood flow, while...

  15. Arterial secondary blood flow patterns visualized with vector flow ultrasound

    DEFF Research Database (Denmark)

    Pedersen, Mads Møller; Pihl, Michael Johannes; Hansen, Jens Munk

    2011-01-01

    This study presents the first quantification and visualisation of secondary flow patterns with vector flow ultrasound. The first commercial implementation of the vector flow method Transverse Oscillation was used to obtain in-vivo, 2D vector fields in real-time. The hypothesis of this study...

  16. Modified Beer-Lambert law for blood flow

    Science.gov (United States)

    Baker, Wesley B.; Parthasarathy, Ashwin B.; Busch, David R.; Mesquita, Rickson C.; Greenberg, Joel H.; Yodh, A. G.

    2015-03-01

    The modified Beer-Lambert law is among the most widely used approaches for analysis of near-infrared spectroscopy (NIRS) reflectance signals for measurements of tissue blood volume and oxygenation. Briefly, the modified Beer-Lambert paradigm is a scheme to derive changes in tissue optical properties based on continuous-wave (CW) diffuse optical intensity measurements. In its simplest form, the scheme relates differential changes in light transmission (in any geometry) to differential changes in tissue absorption. Here we extend this paradigm to the measurement of tissue blood flow by diffuse correlation spectroscopy (DCS). In the new approach, differential changes of the intensity temporal auto-correlation function at a single delay-time are related to differential changes in blood flow. The key theoretical results for measurement of blood flow changes in any tissue geometry are derived, and we demonstrate the new method to monitor cerebral blood flow in a pig under conditions wherein the semi-infinite geometry approximation is fairly good. Specifically, the drug dinitrophenol was injected in the pig to induce a gradual 200% increase in cerebral blood flow, as measured with MRI velocity flow mapping and by DCS. The modified Beer-Lambert law for flow accurately recovered these flow changes using only a single delay-time in the intensity auto-correlation function curve. The scheme offers increased DCS measurement speed of blood flow. Further, the same techniques using the modified Beer-Lambert law to filter out superficial tissue effects in NIRS measurements of deep tissues can be applied to the DCS modified Beer-Lambert law for blood flow monitoring of deep tissues.

  17. Spontaneous oscillations of capillary blood flow in artificial microvascular networks.

    Science.gov (United States)

    Forouzan, Omid; Yang, Xiaoxi; Sosa, Jose M; Burns, Jennie M; Shevkoplyas, Sergey S

    2012-09-01

    Previous computational studies have suggested that the capillary blood flow oscillations frequently observed in vivo can originate spontaneously from the non-linear rheological properties of blood, without any regulatory input. Testing this hypothesis definitively in experiments involving real microvasculature has been difficult because in vivo the blood flow in capillaries is always actively controlled by the host. The objective of this study was to test the hypothesis experimentally and to investigate the relative contribution of different blood cells to the capillary blood flow dynamics under static boundary conditions and in complete isolation from the active regulatory mechanisms mediated by the blood vessels in vivo. To accomplish this objective, we passed whole blood and re-constituted blood samples (purified red blood cells suspended in buffer or in autologous plasma) through an artificial microvascular network (AMVN) comprising completely inert, microfabricated vessels with the architecture inspired by the real microvasculature. We found that the flow of blood in capillaries of the AMVN indeed oscillates with characteristic frequencies in the range of 0-0.6 Hz, which is in a very good agreement with previous computational studies and in vivo observations. We also found that the traffic of leukocytes through the network (typically neglected in computational modeling) plays an important role in generating the oscillations. This study represents the key piece of experimental evidence in support of the hypothesis that spontaneous, self-sustained oscillations of capillary blood flow can be generated solely by the non-linear rheological properties of blood flowing through microvascular networks, and provides an insight into the mechanism of this fundamentally important microcirculatory phenomenon.

  18. [Doppler studies of arterial blood flow in the uterus during labor].

    Science.gov (United States)

    Fendel, H; Fendel, M; Pauen, A; Liedtke, B; Schonlau, H; Warnking, R

    1984-01-01

    By the pulsed doppler method the arterial uterine blood velocity was studied in 19 patients with contractions before and during labour. It is shown, that uterine contractions reduce blood velocity significantly. Normally there is a low resistance in uterine arteries, so that the diastolic flow is nearly as high as the systolic flow. In uterine contractions the vascular resistance increases. Systolic flow is reduced slightly and diastolic flow severely or completely. But a complete zero-flow couldn't observed in any studied uterine contraction.

  19. AN ANALYSIS MODEL OF PULSATILE BLOOD FLOW IN ARTERIES

    Institute of Scientific and Technical Information of China (English)

    LIUZhao-rong; XUGang; CHENYong; TENGZhong0=zhao; QINKai-rong

    2003-01-01

    Blood flow in artery was treated as the flow under equilibriums state(the steady flow under mean pressure)combined with the periodically small pulsatile flow.Using vascular strain energy function advanced by Fung,the vascular stress-strain relationship under equilibrium state was analyzed and the circumferential and axial elastic moduli were deduced that are expressed while the arterial strains around the equilibrium state are relatively small,so that the equations of vesse wall motion under the pulsatile pressure could be established here.Through solving both the vessel equations and the linear Navier-Stokes equations,the analytic expressions of the blood flow velocities and the vascular displacements were obtained.The influence of the difference between vascular circumferentia and axial elasticities on pulsatile blood flow and vascular motion was discussed in details.

  20. AN ANALYSIS MODEL OF PULSATILE BLOOD FLOW IN ARTERIES

    Institute of Scientific and Technical Information of China (English)

    柳兆荣; 徐刚; 陈泳; 滕忠照; 覃开蓉

    2003-01-01

    Blood flow in artery was treated as the flow under equilibrium state ( the steady flow under mean pressure ) combined with the periodically small pulsatile flow. Using vascular strain energy function advanced by Fung, the vascular stress-strain relationship under equilibrium state was analyzed and the circumferential and axial elastic moduli were deduced that are expressed while the arterial strains around the equilibrium state are relatively small, so that the equations of vessel wall motion under the pulsatile pressure could be established here. Through solving both the vessel equations and the linear NavierStokes equations, the analytic expressions of the blood flow velocities and the vascular displacements were obtained. The influence of the difference between vascular circumferential and axial elasticities on pulsatile blood flow and vascular motion was discussed in details.

  1. In-vitro laser anemometry blood flow systems

    Science.gov (United States)

    Liepsch, Dieter W.; Poll, Axel; Pflugbeil, Gottlieb

    1993-08-01

    Lasers are used in a wide variety of medical applications. While laser catheters have been developed for highly accurate velocity measurements these are invasive; noninvasive techniques are more desirable but not as precise. The laser is, however, a great tool for in vitro measurements. Several groups internationally are using the laser in the study of local velocity distribution in microscopic areas of specially constructed models. Laser Doppler anemometry is widely used to measure the local, time-dependent velocities, while phase Doppler anemometry has been developed to measure particle size, distribution and velocity. Most recently, laser analyzer techniques have been developed for analyzing the particle size of two phase flow systems. It has become increasingly important for physicians to visualize blood flow. In addition to the techniques mentioned above, several laser sheet techniques have been developed for precise measurements. This paper presents a short review of laser techniques and shows some applications especially for the laser-Doppler anemometer.

  2. Effects of dopamine infusion on cardiac and renal blood flows in dogs.

    Science.gov (United States)

    Furukawa, Shuji; Nagashima, Yukiko; Hoshi, Katsuichiro; Hirao, Hidehiro; Tanaka, Ryou; Maruo, Kohji; Yamane, Yoshihisa

    2002-01-01

    In veterinary medicine, dopamine is currently being administered clinically by infusion for treatment of kidney disorders at low doses (high doses (> or = 5 microg/kg/min). However, since high doses of dopamine cause peripheral vasoconstriction due to its effect on alpha adrenoceptors, high doses have no longer been recommended. The present study was conducted to explore possible regimens for the use of dopamine infusion in dogs. The regional (renal and cardiac) blood flow for 60 min was measured by using colored microspheres at three doses (3, 10 and 20 microg/kg/min) of dopamine infusion in healthy anesthetized mongrel dogs. The effects on kidney and peripheral hemodynamics at each dose and the resultant cardiac output, mean arterial blood pressure and total peripheral resistance were determined. Renal blood flow increased markedly at 3 microg/kg/min dopamine. Improvement in hemodynamics indicated by marked increase in cardiac blood flow, cardiac output and mean arterial blood pressure and decreased total peripheral resistance was observed at higher doses (10 and 20 microg/kg/min). At 10 microg/kg/min, in addition to the satisfactory increase in cardiac blood flow, there was also a stable satisfactory increase in renal blood flow. However, at 20 microg/kg/min, increased myocardial oxygen consumption (manifested by marked increased in cardiac output), arrythmia and irregular increase in renal blood flow were detected. This study suggests that the clinical use of dopamine infusion in dogs could be safely expanded to moderately higher doses.

  3. Evaluation of changes of intracranial blood flow after carotid artery stenting using digital subtraction angiography flow assessment

    Institute of Scientific and Technical Information of China (English)

    Hajime; Wada; Masato; Saito; Kyousuke; Kamada

    2015-01-01

    AIM: To evaluate the changes of intracranial blood flow after carotid artery stenting(CAS), using the flow assessment application "Flow-Insight", which was developed in our department.METHODS: Twenty patients treated by CAS participated in this study. We analyzed the change in concentration of the contrast media at the anterior-posterior and profile view image with the flow assessment application "Flow-Insight". And we compared the results with N-isopropyl-p-[123I] iodoamphetamine-single-photon emission computed tomography(IMP SPECT) performed before and after the treatment. RESULTS: From this study, 200% of the parameter "blood flow" change in the post/pre-treatment is suggested as the critical line of the hyperperfusion syndrome arise. Although the observed blood flow increase in the digital subtraction angiography system did not strongly correlate with the rate of increase of SPECT, the "Flow-Insight" reflected the rate of change of the vessels well. However, for patients with reduced reserve blood flow before CAS, a highly elevated site was in agreement with the site analysis results. CONCLUSION: We concluded that the cerebral angiography flow assessment application was able to more finely reveal hyperperfusion regions in the brain after CAS compared to SPECT.

  4. High Frame Rate Synthetic Aperture 3D Vector Flow Imaging

    DEFF Research Database (Denmark)

    Villagómez Hoyos, Carlos Armando; Holbek, Simon; Stuart, Matthias Bo

    2016-01-01

    3-D blood flow quantification with high spatial and temporal resolution would strongly benefit clinical research on cardiovascular pathologies. Ultrasonic velocity techniques are known for their ability to measure blood flow with high precision at high spatial and temporal resolution. However......, current volumetric ultrasonic flow methods are limited to one velocity component or restricted to a reduced field of view (FOV), e.g. fixed imaging planes, in exchange for higher temporal resolutions. To solve these problems, a previously proposed accurate 2-D high frame rate vector flow imaging (VFI......) technique is extended to estimate the 3-D velocity components inside a volume at high temporal resolutions (

  5. Interactive retinal blood flow analysis of the macular region.

    Science.gov (United States)

    Tian, Jing; Somfai, Gábor Márk; Campagnoli, Thalmon R; Smiddy, William E; Debuc, Delia Cabrera

    2016-03-01

    The study of retinal hemodynamics plays an important role to understand the onset and progression of diabetic retinopathy. In this work, we developed an interactive retinal analysis tool to quantitatively measure the blood flow velocity (BFV) and blood flow rate (BFR) in the macular region using the Retinal Function Imager (RFI). By employing a high definition stroboscopic fundus camera, the RFI device is able to assess retinal blood flow characteristics in vivo. However, the measurements of BFV using a user-guided vessel segmentation tool may induce significant inter-observer differences and BFR is not provided in the built-in software. In this work, we have developed an interactive tool to assess the retinal BFV and BFR in the macular region. Optical coherence tomography data was registered with the RFI image to locate the fovea accurately. The boundaries of the vessels were delineated on a motion contrast enhanced image and BFV was computed by maximizing the cross-correlation of pixel intensities in a ratio video. Furthermore, we were able to calculate the BFR in absolute values (μl/s). Experiments were conducted on 122 vessels from 5 healthy and 5 mild non-proliferative diabetic retinopathy (NPDR) subjects. The Pearson's correlation of the vessel diameter measurements between our method and manual labeling on 40 vessels was 0.984. The intraclass correlation (ICC) of BFV between our proposed method and built-in software was 0.924 and 0.830 for vessels from healthy and NPDR subjects, respectively. The coefficient of variation between repeated sessions was reduced significantly from 22.5% to 15.9% in our proposed method (p<0.001). Copyright © 2015 Elsevier Inc. All rights reserved.

  6. Local blood flow measured by fluorescence excitation of nonradioactive microspheres

    Energy Technology Data Exchange (ETDEWEB)

    Morita, Y.; Payne, B.D.; Aldea, G.S.; McWatters, C.; Husseini, W.; Mori, H.; Hoffman, J.I.; Kaufman, L. (Univ. of California, San Francisco (USA))

    1990-05-01

    An X-ray fluorescence system with low Compton background and high counting efficiency was developed to measure regional blood flow with nonradioactive microspheres. The performance of the system was tested in vitro by counting mixed aqueous solutions of either Mo, Ag, and I; Nb, Ag, and Ba; or Zr, Mo, Rh, Ag, Sn, I, and Ba, as well as a mixture of Ag and Ba nonradioactive microspheres. Mixtures containing 2-20 ppm of each element were counted for 10 min by the fluorescence system, and the individual elements in mixtures of three to seven nonradioactive elements were measured with high accuracy. The best counting statistics were obtained for Ag. For 10-min counts, the system measures as few as 120 Ag microspheres with 30% standard deviation but measures 800 Ag microspheres per sample with 3.6% standard deviation. We compared regional myocardial blood flows determined simultaneously by fluorescence and radioactive microsphere methods; the latter samples were counted by a 3-in. NaI (Tl) well detector and pulse-height analyzer. The radioactive and nonradioactive measurements showed good correlations.

  7. Study Links Stuttering to Less Blood Flow in Brain

    Science.gov (United States)

    ... medlineplus.gov/news/fullstory_162922.html Study Links Stuttering to Less Blood Flow in Brain The more ... to speech may put people at risk for stuttering, a small study suggests. There are also signs ...

  8. Reduced myocardial blood flow in acute and chronic digitalization.

    Science.gov (United States)

    Steiness, E; Bille-Brahe, N E; Hansen, J F; Lomholt, N; Ring-Larsen, H

    1978-07-01

    The myocardial blood flow was measured by the 133Xenon disappearance curve from the left ventricular wall following an injection of 133Xenon in the left coronary artery in 8 dogs without digoxin pretreatment and in 8 chronically digitalized dogs. The myocardial blood flow was significantly less (30%) in the digitalized dogs than in the dogs without pretreatment. In the digitalized dogs as well as in those without pretreatment an intravenous injection of digoxin resulted in a further significant decrease of the myocardial blood flow of about 20% and a significant increase of the coronary vascular resistance. The reduced myocardial blood flow both during acute and chronic digitalization is beleived to be of clinical importance.

  9. Human red blood cells deformed under thermal fluid flow.

    Science.gov (United States)

    Foo, Ji-Jinn; Chan, Vincent; Feng, Zhi-Qin; Liu, Kuo-Kang

    2006-03-01

    The flow-induced mechanical deformation of a human red blood cell (RBC) during thermal transition between room temperature and 42.0 degrees C is interrogated by laser tweezer experiments. Based on the experimental geometry of the deformed RBC, the surface stresses are determined with the aid of computational fluid dynamics simulation. It is found that the RBC is more deformable while heating through 37.0 degrees C to 42.0 degrees C, especially at a higher flow velocity due to a thermal-fluid effect. More importantly, the degree of RBC deformation is irreversible and becomes softer, and finally reaches a plateau (at a uniform flow velocity U > 60 microm s(-1)) after the heat treatment, which is similar to a strain-hardening dominated process. In addition, computational simulated stress is found to be dependent on the progression of thermotropic phase transition. Overall, the current study provides new insights into the highly coupled temperature and hydrodynamic effects on the biomechanical properties of human erythrocyte in a model hydrodynamic flow system.

  10. Managing Stress to Control High Blood Pressure

    Science.gov (United States)

    ... Aneurysm More Managing Stress to Control High Blood Pressure Updated:Jan 10,2017 The importance of stress ... content was last reviewed October 2016. High Blood Pressure • Home • Get the Facts About HBP • Know Your ...

  11. Avoid the Consequences of High Blood Pressure

    Science.gov (United States)

    ... Thromboembolism Aortic Aneurysm More Avoid the Consequences of High Blood Pressure Infographic Updated:Oct 31,2016 View a downloadable version of this infographic High Blood Pressure • Home • Get the Facts About HBP • Know Your ...

  12. High Blood Pressure: Unique to Older Adults

    Science.gov (United States)

    ... our e-newsletter! Aging & Health A to Z High Blood Pressure Hypertension Unique to Older Adults This section provides ... Pressure Targets are Different for Very Old Adults High blood pressure (also called hypertension) increases your chance of having ...

  13. High Blood Pressure: Keep the Beat Recipes

    Science.gov (United States)

    ... of this page please turn Javascript on. Feature: High Blood Pressure Keep the Beat Recipes Past Issues / Fall 2011 ... 65 million American adults—one in three—with high blood pressure, you have probably heard the advice, "watch your ...

  14. Blood flow rate measurements with indicator techniques revisited

    DEFF Research Database (Denmark)

    Sejrsen, Per; Bülow, Jens

    2009-01-01

    In view of the emerging role, disturbances in regional blood flow rate seem to play in the pathogenesis of the metabolic syndrome; we review the concepts of the classical indicator dilution and washout techniques used for determinations of regional blood flow rate. Prerequisites, assumptions......, necessary precautions for the application of these experimental techniques are emphasized. Special attention has been carried out to elucidate the consequence of a choice of indicators having a large distribution volume in the tissues....

  15. Current Imaging Modalities for assessing Ocular Blood Flow in Glaucoma

    OpenAIRE

    Mohindroo, Chirayu; Ichhpujani, Parul; Kumar, Suresh

    2016-01-01

    Glaucoma may be caused by an interplay of elevated intraocular pressure (IOP), vascular, genetic, anatomical, brain, and immune factors. The direct assessment of ocular hemodynam-ics offers promise for glaucoma detection, differentiation, and possibly new treatment modalities. All the methods currently in use to measure ocular blood flow have inherent limitations and measure different aspects of ocular blood flow. This review article attempts to provide detailed information on ocular perfu-si...

  16. Blood flow and microdialysis in the human femoral head

    DEFF Research Database (Denmark)

    Bøgehøj, Morten; Emmeluth, Claus; Overgaard, Søren

    2007-01-01

    BACKGROUND: If it would be possible to detect lack of flow and/or the development of ischemia in bone, we might have a way of predicting whether a broken bone will heal. We established microdialysis (MD) and laser Doppler (LD) flow measurement in the human femoral head in order to be able to detect...... ischemia and measure changes in blood flow. MATERIAL AND METHODS: In 9 patients undergoing total hip arthroplasty for primary osteoarthrosis, two MD catheters were inserted into the femoral head through two drill holes after the blood flow had been visualized by LD. Then primary samples were collected...... detected within 2 h of cessation of blood flow in most patients....

  17. Numerical Simulation of Unsteady Blood Flow through Capillary Networks.

    Science.gov (United States)

    Davis, J M; Pozrikidis, C

    2011-08-01

    A numerical method is implemented for computing unsteady blood flow through a branching capillary network. The evolution of the discharge hematocrit along each capillary segment is computed by integrating in time a one-dimensional convection equation using a finite-difference method. The convection velocity is determined by the local and instantaneous effective capillary blood viscosity, while the tube to discharge hematocrit ratio is deduced from available correlations. Boundary conditions for the discharge hematocrit at divergent bifurcations arise from the partitioning law proposed by Klitzman and Johnson involving a dimensionless exponent, q≥1. When q=1, the cells are partitioned in proportion to the flow rate; as q tends to infinity, the cells are channeled into the branch with the highest flow rate. Simulations are performed for a tree-like, perfectly symmetric or randomly perturbed capillary network with m generations. When the tree involves more than a few generations, a supercritical Hopf bifurcation occurs at a critical value of q, yielding spontaneous self-sustained oscillations in the absence of external forcing. A phase diagram in the m-q plane is presented to establish conditions for unsteady flow, and the effect of various geometrical and physical parameters is examined. For a given network tree order, m, oscillations can be induced for a sufficiently high value of q by increasing the apparent intrinsic viscosity, decreasing the ratio of the vessel diameter from one generation to the next, or by decreasing the diameter of the terminal vessels. With other parameters fixed, oscillations are inhibited by increasing m. The results of the continuum model are in excellent agreement with the predictions of a discrete model where the motion of individual cells is followed from inlet to outlet.

  18. APPLICATION OF THE THEORY OF INTERACTING CONTINUA TO BLOOD FLOW

    Energy Technology Data Exchange (ETDEWEB)

    Massoudi, Mehrdad; Kim, Jeongho; Hund, Samuel J.; Antaki, James F.

    2011-01-01

    Micro-scale investigations of the flow and deformation of blood and its formed elements have been studied for many years. Early in vitro investigations in the rotational viscometers or small glass tubes revealed important rheological properties such as the reduced blood apparent viscosity, Fahraeus effect and Fahraeus-Lindqvist effect [1], exhibiting the nonhomogeneous property of blood in microcirculation. We have applied Mixture Theory, also known as Theory of Interacting Continua, to study and model this property of blood [2, 3]. This approach holds great promise for predicting the trafficking of RBCs in micro-scale flows (such as the depletion layer near the wall), and other unique hemorheological phenomena relevant to blood trauma. The blood is assumed to be composed of an RBC component modeled as a nonlinear fluid, suspended in plasma, modeled as a linearly viscous fluid.

  19. Experimental comparison of mammalian and avian blood flow in microchannels

    Science.gov (United States)

    Fink, Kathryn; Liepmann, Dorian

    2015-11-01

    The non-Newtonian, shear rate dependent behavior of blood in microchannel fluid dynamics has been studied for nearly a century, with a significant focus on the characteristics of human blood. However, for over 200 years biologists have noted significant differences in red blood cell characteristics across vertebrate species, with particularly drastic differences in cell size and shape between mammals and non-mammalian classes. We present an experimental analysis of flow in long microchannels for several varieties of mammalian and avian blood, across a range of hematocrits, channel diameters, and flow rates. Correlation of shear rate and viscosity is compared to existing constitutive equations for human blood to further quantify the importance of red blood cell characteristics. Ongoing experimental results are made available in an online database for reference or collaboration. K.F. acknowledges funding from the ARCS Foundation and an NSF Graduate Research Fellowship through NSF Grant DGE 1106400.

  20. Establishing the diffuse correlation spectroscopy signal relationship with blood flow.

    Science.gov (United States)

    Boas, David A; Sakadžić, Sava; Selb, Juliette; Farzam, Parisa; Franceschini, Maria Angela; Carp, Stefan A

    2016-07-01

    Diffuse correlation spectroscopy (DCS) measurements of blood flow rely on the sensitivity of the temporal autocorrelation function of diffusively scattered light to red blood cell (RBC) mean square displacement (MSD). For RBCs flowing with convective velocity [Formula: see text], the autocorrelation is expected to decay exponentially with [Formula: see text], where [Formula: see text] is the delay time. RBCs also experience shear-induced diffusion with a diffusion coefficient [Formula: see text] and an MSD of [Formula: see text]. Surprisingly, experimental data primarily reflect diffusive behavior. To provide quantitative estimates of the relative contributions of convective and diffusive movements, we performed Monte Carlo simulations of light scattering through tissue of varying vessel densities. We assumed laminar vessel flow profiles and accounted for shear-induced diffusion effects. In agreement with experimental data, we found that diffusive motion dominates the correlation decay for typical DCS measurement parameters. Furthermore, our model offers a quantitative relationship between the RBC diffusion coefficient and absolute tissue blood flow. We thus offer, for the first time, theoretical support for the empirically accepted ability of the DCS blood flow index ([Formula: see text]) to quantify tissue perfusion. We find [Formula: see text] to be linearly proportional to blood flow, but with a proportionality modulated by the hemoglobin concentration and the average blood vessel diameter.

  1. Stochastic modeling for magnetic resonance quantification of myocardial blood flow

    Science.gov (United States)

    Seethamraju, Ravi T.; Muehling, Olaf; Panse, Prasad M.; Wilke, Norbert M.; Jerosch-Herold, Michael

    2000-10-01

    Quantification of myocardial blood flow is useful for determining the functional severity of coronary artery lesions. With advances in MR imaging it has become possible to assess myocardial perfusion and blood flow in a non-invasive manner by rapid serial imaging following injection of contrast agent. To date most approaches reported in the literature relied mostly on deriving relative indices of myocardial perfusion directly from the measured signal intensity curves. The central volume principle on the other hand states that it is possible to derive absolute myocardial blood flow from the tissue impulse response. Because of the sensitivity involved in deconvolution due to noise in measured data, conventional methods are sub-optimal, hence, we propose to use stochastic time series modeling techniques like ARMA to obtain a robust impulse response estimate. It is shown that these methods when applied for the optical estimation of the transfer function give accurate estimates of myocardial blood flow. The most significant advantage of this approach, compared with compartmental tracer kinetic models, is the use of a minimum set of prior assumptions on data. The bottleneck in assessing myocardial blood flow, does not lie in the MRI acquisition, but rather in the effort or time for post processing. It is anticipated that the very limited requirements for user input and interaction will be of significant advantage for the clinical application of these methods. The proposed methods are validated by comparison with mean blood flow measurements obtained from radio-isotope labeled microspheres.

  2. Hepatic and intestinal blood flow following thermal injury

    Energy Technology Data Exchange (ETDEWEB)

    Carter, E.A.; Tompkins, R.G.; Burke, J.F.

    1988-07-01

    Because cardiac output decreases after burn injuries, investigators have assumed, based upon dye clearance techniques, that hepatic and intestinal blood flow are also decreased following these injuries. Blood flow to the liver, stomach, small intestine, and kidney was determined by the uptake of 201thallium and 125I-labeled fatty acid (para-125I-phenyl-3-methyl pentanoic acid) in a 20% body surface area scald injury that also included plasma volume replacement resuscitation. Uptake of these radioisotopes was determined 15 minutes, 18 hours, and 72 hours after injury. The uptake of the 201thallium and 125I-labeled fatty acid by the gastrointestinal tissues was not statistically different at any of the time periods after comparison of the injured and control (sham-treated) animals. 201Thallium uptake by the kidney was significantly diminished 15 minutes after the burn injury (P less than 0.01). Based on these blood flow measurement techniques, the data suggest that the 20% body surface area scald injury did not alter blood flow to the liver or gastrointestinal tract within the initial 72 hours after the burn injury even though a decrease in renal blood flow was easily detected. These results suggest that the dysfunction of the gastrointestinal system or hepatic system observed after an acute burn injury is not simply the result of hypovolemic shock, which reduces both renal and mesenteric blood flow. These gastrointestinal and hepatic alterations may be related to a factor or factors other than intestinal ischemia.

  3. Radiohalogenated thienylethylamine derivatives for evaluating local cerebral blood flow

    Science.gov (United States)

    Goodman, Mark M.; Knapp, Jr., Furn F.

    1990-01-01

    Radiopharmaceuticals useful in brain imaging comprising radiohalogenated thienylethylamine derivatives. The compounds are 5-halo-thiophene-2-isopropyl amines able to cross the blood-brain barrier and be retained for a sufficient length of time to allow the evaluation or regional blood flow by radioimaging of the brain.

  4. Risk Factors for High Blood Pressure

    Science.gov (United States)

    ... Share this page from the NHLBI on Twitter. Risk Factors for High Blood Pressure Anyone can develop high blood pressure; however, age, ... Lifestyle Habits Unhealthy lifestyle habits can raise your risk for high blood pressure, and they include: Eating too much sodium or ...

  5. Continuous-flow microfluidic blood cell sorting for unprocessed whole blood using surface-micromachined microfiltration membranes.

    Science.gov (United States)

    Li, Xiang; Chen, Weiqiang; Liu, Guangyu; Lu, Wei; Fu, Jianping

    2014-07-21

    White blood cells (WBCs) constitute about 0.1% of the blood cells, yet they play a critical role in innate and adaptive immune responses against pathogenic infections, allergic conditions, and malignancies and thus contain rich information about the immune status of the body. Rapid isolation of WBCs directly from whole blood is a prerequisite for any integrated immunoassay platform designed for examining WBC phenotypes and functions; however, such functionality is still challenging for blood-on-a-chip systems, as existing microfluidic cell sorting techniques are inadequate for efficiently processing unprocessed whole blood on chip with concurrent high throughput and cell purity. Herein we report a microfluidic chip for continuous-flow isolation and sorting of WBCs from whole blood with high throughput and separation efficiency. The microfluidic cell sorting chip leveraged the crossflow filtration scheme in conjunction with a surface-micromachined poly(dimethylsiloxane) (PDMS) microfiltration membrane (PMM) with high porosity. With a sample throughput of 1 mL h(-1), the microfluidic cell sorting chip could recover 27.4 ± 4.9% WBCs with a purity of 93.5 ± 0.5%. By virtue of its separation efficiency, ease of sample recovery, and high throughput enabled by its continuous-flow operation, the microfluidic cell sorting chip holds promise as an upstream component for blood sample preparation and analysis in integrated blood-on-a-chip systems.

  6. Tumor blood flow differs between mouse strains: consequences for vasoresponse to photodynamic therapy.

    Directory of Open Access Journals (Sweden)

    Rickson C Mesquita

    Full Text Available Fluctuations in tumor blood flow are common and attributed to factors such as vasomotion or local vascular structure, yet, because vessel structure and physiology are host-derived, animal strain of tumor propagation may further determine blood flow characteristics. In the present report, baseline and stress-altered tumor hemodynamics as a function of murine strain were studied using radiation-induced fibrosacomas (RIF grown in C3H or nude mice. Fluctuations in tumor blood flow during one hour of baseline monitoring or during vascular stress induced by photodynamic therapy (PDT were measured by diffuse correlation spectroscopy. Baseline monitoring revealed fluctuating tumor blood flow highly correlated with heart rate and with similar median periods (i.e., ∼9 and 14 min in C3H and nudes, respectively. However, tumor blood flow in C3H animals was more sensitive to physiologic or stress-induced perturbations. Specifically, PDT-induced vascular insults produced greater decreases in blood flow in the tumors of C3H versus nude mice; similarly, during baseline monitoring, fluctuations in blood flow were more regular and more prevalent within the tumors of C3H mice versus nude mice; finally, the vasoconstrictor L-NNA reduced tumor blood flow in C3H mice but did not affect tumor blood flow in nudes. Underlying differences in vascular structure, such as smaller tumor blood vessels in C3H versus nude animals, may contribute to strain-dependent variation in vascular function. These data thus identify clear effects of mouse strain on tumor hemodynamics with consequences to PDT and potentially other vascular-mediated therapies.

  7. Microvascular blood flow resistance: Role of red blood cell migration and dispersion.

    Science.gov (United States)

    Katanov, Dinar; Gompper, Gerhard; Fedosov, Dmitry A

    2015-05-01

    Microvascular blood flow resistance has a strong impact on cardiovascular function and tissue perfusion. The flow resistance in microcirculation is governed by flow behavior of blood through a complex network of vessels, where the distribution of red blood cells across vessel cross-sections may be significantly distorted at vessel bifurcations and junctions. In this paper, the development of blood flow and its resistance starting from a dispersed configuration of red blood cells is investigated in simulations for different hematocrit levels, flow rates, vessel diameters, and aggregation interactions between red blood cells. Initially dispersed red blood cells migrate toward the vessel center leading to the formation of a cell-free layer near the wall and to a decrease of the flow resistance. The development of cell-free layer appears to be nearly universal when scaled with a characteristic shear rate of the flow. The universality allows an estimation of the length of a vessel required for full flow development, lc ≲ 25D, for vessel diameters in the range 10 μm red blood cell dispersion at vessel bifurcations and junctions on the flow resistance may be significant in vessels which are shorter or comparable to the length lc. Aggregation interactions between red blood cells generally lead to a reduction of blood flow resistance. The simulations are performed using the same viscosity for both external and internal fluids and the RBC membrane viscosity is not considered; however, we discuss how the viscosity contrast may affect the results. Finally, we develop a simple theoretical model which is able to describe the converged cell-free-layer thickness at steady-state flow with respect to flow rate. The model is based on the balance between a lift force on red blood cells due to cell-wall hydrodynamic interactions and shear-induced effective pressure due to cell-cell interactions in flow. We expect that these results can also be used to better understand the flow

  8. Methods for measurement of cerebral blood flow in man

    DEFF Research Database (Denmark)

    Lassen, N A

    1976-01-01

    A survey of the currently available methods for the measurement of cerebral blood flow in man is given. Many of the clinically important brain diseases such as tumors, stroke, brain trauma or epilepsy entail focal or regional flow alterations. Therefore a special emphasis is placed on methods all...

  9. Blood Flow through an Open-Celled Foam

    Science.gov (United States)

    Ortega, Jason; Maitland, Duncan

    2011-11-01

    The Hazen-Dupuit-Darcy (HDD) equation is commonly used in engineering applications to model the pressure gradient of flow through a porous media. One major advantage of this equation is that it simplifies the complex geometric details of the porous media into two coefficients: the permeability, K, and form factor, C. However through this simplification, the flow details within the porous media are no longer accessible, making it difficult to study the phenomena that contribute to changes in K and C due to clotting of blood flow. To obtain a more detailed understanding of blood flow through a porous media, a direct assessment of the complex interstitial geometry and flow is required. In this study, we solve the Navier-Stokes equations for Newtonian and non-Newtonian blood flow through an open-celled foam geometry obtained from a micro-CT scan. The nominal strut size of the foam sample is of O(10e-5) m and the corresponding Reynolds number based upon this length ranges up to O(10). Fitting the pressure gradient vs. Darcy velocity data with the HDD equation demonstrates that both viscous and inertial forces play an important role in the flow through the foam at these Reynolds numbers. Recirculation zones are observed to form in the wake of the pore struts, producing regions of flow characterized by both low shear rates and long fluid residence times, factors of which have been shown in previous studies to promote blood clotting.

  10. Numerical simulation of the non-Newtonian blood flow through a mechanical aortic valve. Non-Newtonian blood flow in the aortic root

    Science.gov (United States)

    De Vita, F.; de Tullio, M. D.; Verzicco, R.

    2016-04-01

    This work focuses on the comparison between Newtonian and non-Newtonian blood flows through a bileaflet mechanical heart valve in the aortic root. The blood, in fact, is a concentrated suspension of cells, mainly red blood cells, in a Newtonian matrix, the plasma, and consequently its overall behavior is that of a non-Newtonian fluid owing to the action of the cells' membrane on the fluid part. The common practice, however, assumes the blood in large vessels as a Newtonian fluid since the shear rate is generally high and the effective viscosity becomes independent of the former. In this paper, we show that this is not always the case even in the aorta, the largest artery of the systemic circulation, owing to the pulsatile and transitional nature of the flow. Unexpectedly, for most of the pulsating cycle and in a large part of the fluid volume, the shear rate is smaller than the threshold level for the blood to display a constant effective viscosity and its shear thinning character might affect the system dynamics. A direct inspection of the various flow features has shown that the valve dynamics, the transvalvular pressure drop and the large-scale features of the flow are very similar for the Newtonian and non-Newtonian fluid models. On the other hand, the mechanical damage of the red blood cells (hemolysis), induced by the altered stress values in the flow, is larger for the non-Newtonian fluid model than for the Newtonian one.

  11. A multiple disk centrifugal pump as a blood flow device.

    Science.gov (United States)

    Miller, G E; Etter, B D; Dorsi, J M

    1990-02-01

    A multiple disk, shear force, valveless centrifugal pump was studied to determine its suitability as a blood flow device. A pulsatile version of the Tesla viscous flow turbine was designed by modifying the original steady flow pump concept to produce physiological pressures and flows with the aid of controlling circuitry. Pressures and flows from this pump were compared to a Harvard Apparatus pulsatile piston pump. Both pumps were connected to an artificial circulatory system. Frequency and systolic duration were varied over a range of physiological conditions for both pumps. The results indicated that the Tesla pump, operating in a pulsatile mode, is capable of producing physiologic pressures and flows similar to the Harvard pump and other pulsatile blood pumps.

  12. Coded ultrasound for blood flow estimation using subband processing

    DEFF Research Database (Denmark)

    Gran, Fredrik; Udesen, Jesper; Nielsen, Michael bachmann

    2007-01-01

    This paper further investigates the use of coded excitation for blood flow estimation in medical ultrasound. Traditional autocorrelation estimators use narrow-band excitation signals to provide sufficient signal-to-noise-ratio (SNR) and velocity estimation performance. In this paper, broadband...... was carried out using an experimental ultrasound scanner and a commercial linear array 7 MHz transducer. A circulating flow rig was scanned with a beam-to-flow angle of 60 degrees. The flow in the rig was laminar and had a parabolic flow-profile with a peak velocity of 0.09 m/s. The mean relative standard...

  13. The effects of fenoldopam on coronary conduit blood flow after coronary artery bypass graft surgery.

    LENUS (Irish Health Repository)

    Halpenny, M

    2012-02-03

    OBJECTIVE: To quantify the effects of fenoldopam, 0.1 microg\\/kg\\/min, on left internal mammary artery (LIMA) and saphenous vein blood flow after coronary anastomosis. DESIGN: Prospective, randomized, double-blind, placebo-controlled trial. SETTING: University teaching hospital, single institution. PARTICIPANTS: Thirty-one American Society of Anesthesiologists III patients undergoing elective coronary revascularization. INTERVENTIONS: A perivascular ultrasonic flow probe (Linton Instrumentation, Norfolk, UK) was placed around the LIMA and saphenous vein graft after coronary anastomosis. MEASUREMENTS AND MAIN RESULTS: Immediately before and at 5-minute intervals for 15 minutes after starting the infusion, blood flow was measured in the LIMA and one saphenous vein graft using a transit time ultrasonic flow probe. Heart rate, blood pressure, and central venous pressure were documented at these time points. Administration of fenoldopam, 0.1 microg\\/kg\\/min, did not alter heart rate or blood pressure. A small, nonsignificant increase in LIMA blood flow occurred during the 15-minute study period (30 +\\/- 12 to 35 +\\/- 10 mL\\/min) in patients who received fenoldopam. No significant changes occurred in the placebo group. CONCLUSIONS: The findings indicate that fenoldopam, 0.1 microg\\/kg\\/min, did not influence coronary conduit blood flow to a clinically significant extent. The small increase in LIMA blood flow may be of greater importance in high-risk patients or in the prevention of coronary arterial spasm.

  14. Ultrasonic Imaging of Hemodynamic Force in Carotid Blood Flow

    Science.gov (United States)

    Nitta, N.; Homma, K.

    Hemodynamic forces including blood pressure and shear stress affect vulnerable plaque rupture in arteriosclerosis and biochemical activation of endothelium such as NO production. In this study, a method for estimating and imaging shear stress and pressure gradient distributions in blood vessel as the hemodynamic force based on viscosity estimation is presented. Feasibility of this method was investigated by applying to human carotid blood flow. Estimated results of shear stress and pressure gradient distributions coincide with the ideal distributions obtained by numerical simulation and flow-phantom experiment.

  15. Capillary pericytes regulate cerebral blood flow in health and disease

    DEFF Research Database (Denmark)

    Hall, Catherine N; Reynell, Clare; Gesslein, Bodil

    2014-01-01

    that neuronal activity and the neurotransmitter glutamate evoke the release of messengers that dilate capillaries by actively relaxing pericytes. Dilation is mediated by prostaglandin E2, but requires nitric oxide release to suppress vasoconstricting 20-HETE synthesis. In vivo, when sensory input increases......Increases in brain blood flow, evoked by neuronal activity, power neural computation and form the basis of BOLD (blood-oxygen-level-dependent) functional imaging. Whether blood flow is controlled solely by arteriole smooth muscle, or also by capillary pericytes, is controversial. We demonstrate...

  16. Muscle Tissue Saturation Compared With Muscle Tissue Perfusion During Low Blood Flows

    DEFF Research Database (Denmark)

    Thomassen, Sisse Anette; Kjærgaard, Benedict; Olsen Alstrup, Aage Kristian

    2017-01-01

    OBJECTIVE: To investigate whether changes in muscle tissue perfusion measured with positron emission tomography would be reflected by parallel changes in muscle tissue oxygen saturation (StO2) measured using near-infrared spectroscopy during high and low blood flow levels achieved using...... blood flow of either 47.5 or 35 mL/kg/min was applied for 1 hour followed by a blood flow of 60 mL/kg/min for an additional hour. Regional StO2 was measured continuously by placing a near-infrared spectroscopy electrode on the skin above the gracilis muscle of the noncannulated back leg. Muscle tissue...... systemic ischemia during low CPB blood flow. StO2 remained high until muscle tissue perfusion decreased to about 50%, after which StO2 paralleled the linear decrease in muscle tissue perfusion. CONCLUSION: In an experimental CPB animal model, StO2 was stable until muscle tissue perfusion was reduced...

  17. Transcranial Doppler-determined change in posterior cerebral artery blood flow velocity does not reflect vertebral artery blood flow during exercise.

    Science.gov (United States)

    Washio, Takuro; Sasaki, Hiroyuki; Ogoh, Shigehiko

    2017-02-10

    We examined whether a change in posterior cerebral artery flow velocity (PCAv) reflected the posterior cerebral blood flow, in healthy subjects, during both static and dynamic exercise. PCAv and vertebral artery (VA) blood flow, as an index of posterior blood flow, were continuously measured during an exercise trial, using transcranial Doppler (TCD) ultrasonography and Doppler ultrasound, respectively. Static handgrip exercise significantly increased both PCAv and VA blood flow. Increasing intensity of dynamic exercise further increased VA blood flow from moderate exercise, while PCAv decreased to almost resting level. During both static and dynamic exercise, the PCA cerebrovascular conductance (CVC) index significantly decreased from rest (static and high intensity dynamic exercise; -11.5 ± 12.2% and -18.0 ± 16.8%; mean ± SD, respectively), despite no change in the CVC of VA. These results indicate that vasoconstriction occurred at PCA but not VA during exercise-induced hypertension. This discrepancy in vascular response to exercise between PCA and VA may be due to different cerebral arterial characteristics. Therefore, to determine the effect of exercise on posterior cerebral circulation, at least, we need to consider carefully which cerebral artery to measure, regardless of exercise mode.

  18. Quantifying Blood Flow in the DIEP Flap: An Ultrasonographic Study

    Directory of Open Access Journals (Sweden)

    Joseph Richard Dusseldorp, BCom, MBBS(Hons

    2014-10-01

    Conclusions: This study confirms that perforator size is a critical factor in optimizing blood flow in perforator-based free tissue transfer. Further research is required to understand the flow dynamics of perforator flaps based on multiple perforators. However, surgeons should be cognizant that a single large perforator may have substantially higher flow rates than multiple small perforators. Routine FVI calculation is recommended to ensure complete flap survival.

  19. The effects of hypoxemia on myocardial blood flow during exercise.

    Science.gov (United States)

    Paridon, S M; Bricker, J T; Dreyer, W J; Reardon, M; Smith, E O; Porter, C B; Michael, L; Fisher, D J

    1989-03-01

    We evaluated the adequacy of regional and transmural blood flow during exercise and rapid pacing after 1 wk of hypoxemia. Seven mature mongrel dogs were made hypoxemic (mean O2 saturation = 72.4%) by anastomosis of left pulmonary artery to left atrial appendage. Catheters were placed in the left atrium, right atrium, pulmonary artery, and aorta. Atrial and ventricular pacing wires were placed. An aortic flow probe was placed to measure cardiac output. Ten nonshunted dogs, similarly instrumented, served as controls. Recovery time was approximately 1 wk. Cardiac output, mean aortic pressure, and oxygen saturation were measured at rest, with ventricular pacing, atrial pacing, and with treadmill exercise. Ventricular and atrial pace and exercise were at a heart rate of 200. Right ventricular free wall, left ventricular free wall, and septal blood flow were measured with radionuclide-labeled microspheres. Cardiac output, left atrial blood pressure, and aortic blood pressure were similar between the two groups of dogs in all testing states. Myocardial blood flow was significantly higher in the right and left ventricular free wall in the hypoxemic animals during resting and exercise testing states. Myocardial oxygen delivery was similar between the two groups of animals. Pacing resulted in an increase in myocardial blood flow in the control animals but not the hypoxemic animals.(ABSTRACT TRUNCATED AT 250 WORDS)

  20. Regional cerebral blood flow in focal cortical epilepsy

    DEFF Research Database (Denmark)

    Hougaard, Kristina Dupont; Oikawa, T; Sveinsdottir, E

    1976-01-01

    Regional cerebral blood flow (rCBF) was studied in ten patients with focal cortical epilepsy. The blood flow was measured by the intra-arterial injection of xenon 133 (133Xe), and the isotope clearance was recorded by a multidetector scintillation camera with 254 detectors. Three patients were....... This finding accords with earlier studies. All nine patients studied in the interictal phase showed, either spontaneously or during activation by intermittent light, focal flow increases in areas presumed to comprise the epileptic focus. These interictal hyperemic foci probably reflect subictal neuronal...

  1. Cerebral blood flow tomography with xenon-133

    DEFF Research Database (Denmark)

    Lassen, N A

    1985-01-01

    and investigative purposes. This article discusses in particular its use for the selection of patients with carotid occlusion for extracranial/intracranial bypass surgery, for detection of severe arterial spasm after aneurysm bleeding, and for detection of low flow areas during severe migraine attacks. The use...

  2. Tubuloglomerular feedback dynamics and renal blood flow autoregulation in rats

    DEFF Research Database (Denmark)

    Holstein-Rathlou, N H; Wagner, A J; Marsh, D J

    1991-01-01

    To decide whether tubuloglomerular feedback (TGF) can account for renal autoregulation, we tested predictions of a TGF simulation. Broad-band and single-frequency perturbations were applied to arterial pressure; arterial blood pressure, renal blood flow and proximal tubule pressure were measured....... Data were analyzed by linear systems analysis. Broad-band forcings of arterial pressure were also applied to the model to compare experimental results with simulations. With arterial pressure as the input and tubular pressure, renal blood flow, or renal vascular resistance as outputs, the model......Hz in which, in addition, there are autonomous oscillations in TGF. Higher amplitude forcings in this band were attenuated by autoregulatory mechanisms, but low-amplitude forcings entrained the autonomous oscillations and provoked amplified oscillations in blood flow, showing an effect of TGF on whole kidney...

  3. Viscoelastic capillary flow: the case of whole blood

    Directory of Open Access Journals (Sweden)

    David Rabaud

    2016-07-01

    Full Text Available The dynamics of spontaneous capillary flow of Newtonian fluids is well-known and can be predicted by the Lucas-Washburn-Rideal (LWR law. However a wide variety of viscoelastic fluids such as alginate, xanthan and blood, does not exhibit the same Newtonian behavior.In this work we consider the Herschel-Bulkley (HB rheological model and Navier-Stokes equation to derive a generic expression that predicts the capillary flow of non-Newtonian fluids. The Herschel-Bulkley rheological model encompasses a wide variety of fluids, including the Power-law fluids (also called Ostwald fluids, the Bingham fluids and the Newtonian fluids. It will be shown that the proposed equation reduces to the Lucas-Washburn-Rideal law for Newtonian fluids and to the Weissenberg-Rabinowitsch-Mooney (WRM law for power-law fluids. Although HB model cannot reduce to Casson’s law, which is often used to model whole blood rheology, HB model can fit the whole blood rheology with the same accuracy.Our generalized expression for the capillary flow of non-Newtonian fluid was used to accurately fit capillary flow of whole blood. The capillary filling of a cylindrical microchannel by whole blood was monitored. The blood first exhibited a Newtonian behavior, then after 7 cm low shear stress and rouleaux formation made LWR fails to fit the data: the blood could not be considered as Newtonian anymore. This non-Newtonian behavior was successfully fit by the proposed equation.

  4. Age and gender related differences in aortic blood flow

    DEFF Research Database (Denmark)

    Traberg, Marie Sand; Pedersen, Mads Møller; Hemmsen, Martin Christian

    2012-01-01

    The abdominal aorta (AA) is predisposed to development of abdominal aneurysms (AAA), a focal dilatation of the artery with fatal consequences if left untreated. The blood flow patterns in the AA is thought to play an important role in the development of AAA. The purpose of this work is to investi......The abdominal aorta (AA) is predisposed to development of abdominal aneurysms (AAA), a focal dilatation of the artery with fatal consequences if left untreated. The blood flow patterns in the AA is thought to play an important role in the development of AAA. The purpose of this work...... is to investigate the blood flow pat- terns within a group of healthy volunteers (4 females, 7 males) aged 23 to 76 years to identify changes and differences related to age and gender. The healthy volunteers were categorized by gender (male/female) and age (below/above 35 years). Subject-specific flow and geometry...... to elderly. Thus, changes in blood flow patterns in the AA related to age and gender is observed. Further investigations are needed to determine the relation between changes in blood flow patterns and AAA development....

  5. Comparison of detection pattern of HCC by ferumoxide-enhanced MRI and intratumoral blood flow pattern

    Energy Technology Data Exchange (ETDEWEB)

    Itou, Naoki; Kotake, Fumio [Tokyo Medical Coll., Ami, Ibaraki (Japan). Kasumigaura Hospital; Saitou, Kazuhiro; Abe, Kimihiko

    2000-08-01

    We compared the detection rate and pattern of ferumoxide-enhanced magnetic resonance imaging (Fe-MRI) with the intratumoral blood flow pattern determined by CT angiography (CTA) and CT portography (CTAP) in 124 nodes (34 cases) diagnosed as hepatocellular carcinoma (HCC) or borderline HCC, based on the clinical course. Sequences to obtain a T1-weighted images (T1W), proton density-weighted images (PDW), T2-weighted images (T2W), T2*-weighted images (T2*W) were used in Fe-MRI. In nodes shown to be hypervascular on CTA, the detection rate by Fe-MRI was 69.7%. In nodes shown to be avascular by CTAP, the detection rate by Fe-MRI was 67.3%. These rates were higher than with other flow patterns. In nodes showing high signal intensity (HSI) on any sequences, arterial blood flow was increased and portal blood flow decreased in comparison with nodes without high signal intensity. All nodes showing HSI, both on Fe-MRI T2W and T2*W, were hypervascular on CTA, and portal blood flow was absent on CTAP. Nodes showing HSI on both T2*W and T2W were considered to have greater arterial blood flow and decreased portal blood flow compared with nodes appearing as HSI on T2*W, but only as iso- or low signal intensity on T2W (Mann-Whitney U-test; p<0.05). (author)

  6. Fibro-Vascular Coupling in the Control of Cochlear Blood Flow

    OpenAIRE

    Min Dai; Xiaorui Shi

    2011-01-01

    BACKGROUND: Transduction of sound in the cochlea is metabolically demanding. The lateral wall and hair cells are critically vulnerable to hypoxia, especially at high sound levels, and tight control over cochlear blood flow (CBF) is a physiological necessity. Yet despite the importance of CBF for hearing, consensus on what mechanisms are involved has not been obtained. METHODOLOGY/PRINCIPAL FINDINGS: We report on a local control mechanism for regulating inner ear blood flow involving fibrocyte...

  7. Intrinsic regulation of blood flow in adipose tissue

    DEFF Research Database (Denmark)

    Henriksen, O; Nielsen, Steen Levin; Paaske, W

    1976-01-01

    Previous studies on intact human subcutaneous tissue have shown, that blood flow remains constant during minor changes in perfusion pressure. This so-called autoregulatory response has not been demonstrable in isolated preparations of adipose tissue. In the present study on isolated, denervated...... subcutaneous tissue in female rabbits only 2 of 12 expts. revealed an autoregulatory response during reduction in arterial perfusion pressure. Effluent blood flow from the tissue in the control state was 15.5 ml/100 g-min (S.D. 6.4, n = 12) corresponding to slight vasodilatation of the exposed tissue....... Following total ischemia all experiments showed a period with reactive hyperemia, and both duration of hyperemia and excess flow was related to the duration of the ischemia. This response therefore seems more resistant to the experimental procedure, while autoregulation of blood flow to lowered pressure...

  8. Pulsatile blood flow, shear force, energy dissipation and Murray's Law

    Directory of Open Access Journals (Sweden)

    Bengtsson Hans-Uno

    2006-08-01

    Full Text Available Abstract Background Murray's Law states that, when a parent blood vessel branches into daughter vessels, the cube of the radius of the parent vessel is equal to the sum of the cubes of the radii of daughter blood vessels. Murray derived this law by defining a cost function that is the sum of the energy cost of the blood in a vessel and the energy cost of pumping blood through the vessel. The cost is minimized when vessel radii are consistent with Murray's Law. This law has also been derived from the hypothesis that the shear force of moving blood on the inner walls of vessels is constant throughout the vascular system. However, this derivation, like Murray's earlier derivation, is based on the assumption of constant blood flow. Methods To determine the implications of the constant shear force hypothesis and to extend Murray's energy cost minimization to the pulsatile arterial system, a model of pulsatile flow in an elastic tube is analyzed. A new and exact solution for flow velocity, blood flow rate and shear force is derived. Results For medium and small arteries with pulsatile flow, Murray's energy minimization leads to Murray's Law. Furthermore, the hypothesis that the maximum shear force during the cycle of pulsatile flow is constant throughout the arterial system implies that Murray's Law is approximately true. The approximation is good for all but the largest vessels (aorta and its major branches of the arterial system. Conclusion A cellular mechanism that senses shear force at the inner wall of a blood vessel and triggers remodeling that increases the circumference of the wall when a shear force threshold is exceeded would result in the observed scaling of vessel radii described by Murray's Law.

  9. High blood pressure and visual sensitivity

    Science.gov (United States)

    Eisner, Alvin; Samples, John R.

    2003-09-01

    The study had two main purposes: (1) to determine whether the foveal visual sensitivities of people treated for high blood pressure (vascular hypertension) differ from the sensitivities of people who have not been diagnosed with high blood pressure and (2) to understand how visual adaptation is related to standard measures of systemic cardiovascular function. Two groups of middle-aged subjects-hypertensive and normotensive-were examined with a series of test/background stimulus combinations. All subjects met rigorous inclusion criteria for excellent ocular health. Although the visual sensitivities of the two subject groups overlapped extensively, the age-related rate of sensitivity loss was, for some measures, greater for the hypertensive subjects, possibly because of adaptation differences between the two groups. Overall, the degree of steady-state sensitivity loss resulting from an increase of background illuminance (for 580-nm backgrounds) was slightly less for the hypertensive subjects. Among normotensive subjects, the ability of a bright (3.8-log-td), long-wavelength (640-nm) adapting background to selectively suppress the flicker response of long-wavelength-sensitive (LWS) cones was related inversely to the ratio of mean arterial blood pressure to heart rate. The degree of selective suppression was also related to heart rate alone, and there was evidence that short-term changes of cardiovascular response were important. The results suggest that (1) vascular hypertension, or possibly its treatment, subtly affects visual function even in the absence of eye disease and (2) changes in blood flow affect retinal light-adaptation processes involved in the selective suppression of the flicker response from LWS cones caused by bright, long-wavelength backgrounds.

  10. Partitioning of red blood cell aggregates in bifurcating microscale flows

    Science.gov (United States)

    Kaliviotis, E.; Sherwood, J. M.; Balabani, S.

    2017-03-01

    Microvascular flows are often considered to be free of red blood cell aggregates, however, recent studies have demonstrated that aggregates are present throughout the microvasculature, affecting cell distribution and blood perfusion. This work reports on the spatial distribution of red blood cell aggregates in a T-shaped bifurcation on the scale of a large microvessel. Non-aggregating and aggregating human red blood cell suspensions were studied for a range of flow splits in the daughter branches of the bifurcation. Aggregate sizes were determined using image processing. The mean aggregate size was marginally increased in the daughter branches for a range of flow rates, mainly due to the lower shear conditions and the close cell and aggregate proximity therein. A counterintuitive decrease in the mean aggregate size was apparent in the lower flow rate branches. This was attributed to the existence of regions depleted by aggregates of certain sizes in the parent branch, and to the change in the exact flow split location in the T-junction with flow ratio. The findings of the present investigation may have significant implications for microvascular flows and may help explain why the effects of physiological RBC aggregation are not deleterious in terms of in vivo vascular resistance.

  11. How Is High Blood Pressure Treated?

    Science.gov (United States)

    ... or focusing on something calm or peaceful Performing yoga or tai chi Meditating Medicines Blood pressure medicines work in different ways to stop or slow some of the body’s functions that cause high blood pressure. Medicines to lower ...

  12. Complex blood flow quantification using real-time in vivo vector flow ultrasound

    DEFF Research Database (Denmark)

    Pedersen, Mads Møller; Pihl, Michael Johannes; Per, Haugaard;

    A new method to define and quantify complex blood flow is presented. The standard deviations of real-time in vivo vector flow angle estimates are used. Using vector flow ultrasound imaging both carotid bifurcations of two healthy volunteers were scanned. Scanning was performed with a 7.6 MHz linear...... patterns can be visualised and quantified with real-time in vivo vector flow. Good agreement between visual evaluation and the quantitative method has been shown. A standard deviation of vector angle estimates above 30 is proposed to define complex blood flow....

  13. Caring for patients with lesions increasing pulmonary blood flow.

    Science.gov (United States)

    Moynihan, P J; King, R

    1989-06-01

    The most common congenital cardiac defect is VSD. This malady accounts for 20 to 30 per cent of all congenital cardiac defects and is representative of a cardiac lesion that increases pulmonary blood flow. Although lesions, which increase pulmonary blood flow, may vary in incidence, they frequently have common symptomatology. Over time, congestive heart failure becomes a problem. Poor respiratory status leads to weight loss, poor feeding, and failure to thrive. If unrepaired, the child often presents with cyanosis and tachypnea. The history may include frequent respiratory infections, exercise intolerance, generalized malaise, or fatigue. In spite of poor weight gain, the child may be edematous and have a large liver. Definitive diagnosis of each lesion may be made by echocardiogram, cardiac catheterization, or both. With these data and a detailed history, treatment and management decisions are determined. In most cases, as the child gets older, symptoms become more evident. This is the result of high pulmonary pressure. High pressure over time causes a thickening of the alveolar tissue, which decreases the permeability of the alveolar membranes for gas exchange. Lung changes can become irreversible, but it is unusual for irreversible changes to occur before 1 year of age. All the lesions described in this article are amendable to primary repair before 1 year of age, affording the best functional results. Postoperative nursing care includes management of persisting CHF and PVR while maintaining adequate cardiac output. Many factors, including electrolyte balance, nutritional status, conduction disturbances, stress, and parental anxiety, influence the management of these infants. The outcome depends greatly on the assessment skill of a highly competent cardiac intensive care nurse and an environment conducive to collaborative practice.

  14. Peripheral blood flow control in diabetes mellitus

    DEFF Research Database (Denmark)

    Hilsted, Jannik

    1991-01-01

    Long term diabetes has a profound effect on the peripheral circulation. This has been demonstrated to be due to the presence of angiopathy and autonomic neuropathy, affecting autoregulation and distensibility of the vessels as well as local and central reflex regulation of the vascular resistance....... Whereas the hemodynamic consequences of vascular denervation are well known (causing blood pressure maladaptation to a number of stimuli such as standing, exercise and agonist infusion) (Hilsted 1985), the consequences of disturbances in autoregulation and distensibility remain to be established....

  15. HIGH BLOOD PRESSURE: DOES THIS CONCERN ME?

    CERN Multimedia

    2007-01-01

    To find out, the Medical Service's nurses are organising A HIGH BLOOD PRESSURE SCREENING AND PREVENTION CAMPAIGN from Monday, 26th to Thursday, 29th March 2007 at the Infirmary - Building 57 - ground floor A blood pressure test, advice, information and, if necessary, referral for specialist medical treatment will be offered to any person working on the CERN site. High blood pressure is a stealth threat to health. So come and get your blood pressure checked.

  16. HIGH BLOOD PRESSURE: DOES THIS CONCERN ME?

    CERN Multimedia

    2007-01-01

    To find out, the Medical Service's nurses are organising A HIGH BLOOD PRESSURE SCREENING AND PREVENTION CAMPAIGN from Monday, 26th to Thursday, 29th March 2007 at the Infirmary - Building 57 - ground floor A blood pressure test, advice, information and, if necessary, referral for specialist medical treatment will be offered to any person working on the CERN site. High blood pressure is a silent threat to health. So come and get your blood pressure checked.

  17. Estimation of vessel diameter and blood flow dynamics from laser speckle images

    DEFF Research Database (Denmark)

    Postnov, Dmitry D.; Tuchin, Valery V.; Sosnovtseva, Olga

    2016-01-01

    Laser speckle imaging is a rapidly developing method to study changes of blood velocity in the vascular networks. However, to assess blood flow and vascular responses it is crucial to measure vessel diameter in addition to blood velocity dynamics. We suggest an algorithm that allows for dynamical...... masking of a vessel position and measurements of it's diameter from laser speckle images. This approach demonstrates high reliability and stability....

  18. Design and Simulation of Axial Flow Maglev Blood Pump

    Directory of Open Access Journals (Sweden)

    Huachun Wu

    2011-03-01

    Full Text Available The axial flow maglev blood pump (AFMBP has become a global research focus and emphasis for artificial ventricular assist device, which has no mechanical contact, mechanical friction, compact structure and light weight, can effectively solve thrombus and hemolysis. Magnetic suspension and impeller is two of the important parts in the axial flow maglev blood pump, and their structure largely determines the blood pump performance. The research adopts electromagnetic and fluid finite element analysis, and puts forward a method to design the magnetic suspension and impeller of axial flow blood pump, which tacks into account the small volume of axial blood pump. The magnetic bearing’s characteristics are evaluated by electromagnetic finite element analysis. The Blades have been designed by calculating aerofoil bone line, and make simulation analysis for different thicken ways of blade by Fluent software, and make a conclusion that the blade thickened with certain rules has better characteristics in the same conditions. The results will provide some guidance for design of axial flow maglev blood pump, and establish theoretical basis for application of the implantable artificial heart pump.

  19. [The landmarks of the measurement of cerebral blood flow].

    Science.gov (United States)

    István, Nyáry

    2008-01-30

    History of the measurement of local cerebral blood flow may cover a period of one and a half centuries. Parallel forthcoming of both theoretical and technical development were the key elements of ensuing progress resulting in the present state, when by the aid of in vivo blood flow and metabolic maps, we can visualize locales of brain functioning and their interconnections. Two theoretical landmarks should be mentioned in this historic process. First, the work of Adolf Fick, as the starter of quantitative measurements in this field, and Seymour Kety's model of a single, homogenously perfused tissue element. The solution of this model, in the form of Kety's equation is still fundamental to present day blood flow mapping techniques. Among the numerous investigators over the past years, two Hungarian scientist can be named as major contributors. Kálmán Sántha made substantial studies with continuous registration of local cerebral blood flow by the aid of thermocouples, while Emil P6sztor invented the hydrogen clearance method for the measurement of local cerebral blood flow both in human and in animal studies.

  20. Regional neurohypophysial and hypothalamic blood flow in rats during hypercapnia

    Energy Technology Data Exchange (ETDEWEB)

    Bryan, R.M. Jr.; Myers, C.L.; Page, R.B.

    1988-08-01

    Regional cerebral blood flow (rCBF) was measured in the neurohypophysis and hypothalamus in normocapnic and hypercapnic rats using (/sup 14/C)isopropyliodoamphetamine. Rats were surgically prepared using nitrous oxide and halothane and placed in plaster restraining casts. Hypercapnia was produced by increasing the fractional concentration of inspired CO/sub 2/ (FICO/sub 2/). rCBF in normocapnic rats was higher in the paraventricular nucleus, supraoptic nucleus, median eminence, and neural lobe than rates previously measured by use of diffusible tracers. During hypercapnia blood flow increased linearly with arterial PCO/sub 2/ (PACO/sub 2/) in all regions except the median eminence and neural lobe, which were not affected by hypercapnia. When rats were pretreated with phentolamine (1 mg/kg) to block the alpha-adrenergic receptors, blood flow in the median eminence and neural lobe increased significantly during hypercapnia. We conclude that blood flow in the cell bodies of the paraventricular nucleus and supraoptic nucleus is regulated differently during hypercapnia than blood flow in the nerve terminals in the median eminence and neural lobe. Furthermore, vasodilation produced by increased CO/sub 2/ is offset by alpha-receptor stimulation in the median eminence and neural lobe.

  1. Hybrid PIV-PTV technique for measuring blood flow in rat mesenteric vessels.

    Science.gov (United States)

    Ha, Hojin; Nam, Kweon-Ho; Lee, Sang Joon

    2012-11-01

    The micro-particle tracking velocimetry (μ-PTV) technique is used to obtain the velocity fields of blood flow in the microvasculature under in vivo conditions because it can provide the blood velocity distribution in microvessels with high spatial resolution. The in vivo μ-PTV technique usually requires a few to tens of seconds to obtain a whole velocity profile across the vessel diameter because of the limited number density of tracer particles under in vivo conditions. Thus, the μ-PTV technique alone is limited in measuring unsteady blood flows that fluctuate irregularly due to the heart beating and muscle movement in surrounding tissues. In this study, a new hybrid PIV-PTV technique was established by combining PTV and particle image velocimetry (PIV) techniques to resolve the drawbacks of the μ-PTV method in measuring blood flow in microvessels under in vivo conditions. Images of red blood cells (RBCs) and fluorescent particles in rat mesenteric vessels were obtained simultaneously. Temporal variations of the centerline blood velocity were monitored using a fast Fourier transform-based cross-correlation PIV method. The fluorescence particle images were analyzed using the μ-PTV technique to extract the spatial distribution of the velocity vectors. Data from the μ-PTV and PIV methods were combined to obtain a better estimate of the velocity profile in actual blood flow. This technique will be useful in investigating hemodynamics in microcirculation by measuring unsteady irregular blood flows more accurately.

  2. Numerical method of characteristics for one-dimensional blood flow

    CERN Document Server

    Acosta, Sebastian; Riviere, Beatrice; Penny, Daniel J; Rusin, Craig G

    2014-01-01

    Mathematical modeling at the level of the full cardiovascular system requires the numerical approximation of solutions to a one-dimensional nonlinear hyperbolic system describing flow in a single vessel. This model is often simulated by computationally intensive methods like finite elements and discontinuous Galerkin, while some recent applications require more efficient approaches (e.g. for real-time clinical decision support, phenomena occurring over multiple cardiac cycles, iterative solutions to optimization/inverse problems, and uncertainty quantification). Further, the high speed of pressure waves in blood vessels greatly restricts the time-step needed for stability in explicit schemes. We address both cost and stability by presenting an efficient and unconditionally stable method for approximating solutions to diagonal nonlinear hyperbolic systems. Theoretical analysis of the algorithm is given along with a comparison of our method to a discontinuous Galerkin implementation. Lastly, we demonstrate the ...

  3. Measurement of cerebral blood flow rate and its relationship with brain function using optical coherence tomography

    Science.gov (United States)

    Liu, Jian; Wang, Yi; Zhao, Yuqian; Dou, Shidan; Ma, Yushu; Ma, Zhenhe

    2016-03-01

    Activity of brain neurons will lead to changes in local blood flow rate (BFR). Thus, it is important to measure the local BFR of cerebral cortex on research of neuron activity in vivo, such as rehabilitation evaluation after stroke, etc. Currently, laser Doppler flowmetry is commonly used for blood flow measurement, however, relatively low resolution limits its application. Optical coherence tomography (OCT) is a powerful noninvasive 3D imaging modality with high temporal and spatial resolutions. Furthermore, OCT can provide flow distribution image by calculating Doppler frequency shift which makes it possible for blood flow rate measurement. In this paper, we applied OCT to measure the blood flow rate of the primary motor cortex in rats. The animal was immobilized and anesthetized with isoflurane, an incision was made along the sagittal suture, and bone was exposed. A skull window was opened on the primary motor cortex. Then, blood flow rate changes in the primary motor cortex were monitored by our homemade spectral domain OCT with a stimulation of the passive movement of the front legs. Finally, we established the relationship between blood flow rate and the test design. The aim is to demonstrate the potential of OCT in the evaluation of cerebral cortex function.

  4. High blood pressure in women.

    Science.gov (United States)

    Calhoun, D A; Oparil, S

    1997-01-01

    There is a sexual dimorphism in blood pressure of humans and experimental animals: males tend to have higher blood pressure than females with functional ovaries, while ovariectomy or menopause tends to abolish the sexual dimorphism and cause females to develop a "male" pattern of blood pressure. Hypertensive male laboratory animals tend to have NaCl-sensitive blood pressure, while females are NaCl resistant unless their ovaries are removed, in which case NaCl sensitivity appears. The hormonal basis of NaCl sensitivity of blood pressure and of the sexual dimorphism of hypertension remains to be defined. Synthetic estrogens and progestins, as found in oral contraceptives, tend to elevate blood pressure, while naturally occurring estrogens lower it, or have no effect. Hypertension increases cardiovascular risk in women, as well as men, although the benefits of antihypertensive treatment have been more difficult to demonstrate in women. In the population of the United States, women are more aware of their hypertension, more likely to be treated medically, and more likely to have their blood pressure controlled.

  5. Quantitative myocardial blood flow with Rubidium-82 PET

    DEFF Research Database (Denmark)

    Hagemann, Christoffer E; Ghotbi, Adam A; Kjær, Andreas

    2015-01-01

    Positron emission tomography (PET) allows assessment of myocardial blood flow in absolute terms (ml/min/g). Quantification of myocardial blood flow (MBF) and myocardial flow reserve (MFR) extend the scope of conventional semi-quantitative myocardial perfusion imaging (MPI): e.g. in 1) identificat......Positron emission tomography (PET) allows assessment of myocardial blood flow in absolute terms (ml/min/g). Quantification of myocardial blood flow (MBF) and myocardial flow reserve (MFR) extend the scope of conventional semi-quantitative myocardial perfusion imaging (MPI): e.g. in 1...... pretest probability of CAD can support the clinical decision-making in treatment of CAD patients as a complementary tool to the invasive coronary angiography (CAG). Recently, several studies have proven Rubidium-82 ((82)Rb) PET's long-term prognostic value by a significant association between compromised...... global MFR and major adverse cardiovascular events (MACE), and together with new diagnostic possibilities from measuring the longitudinal myocardial perfusion gradient, cardiac (82)Rb PET faces a promising clinical future. This article reviews current evidence on quantitative (82)Rb PET's ability...

  6. Impact of extracorporeal blood flow rate on blood pressure, pulse rate and cardiac output during haemodialysis

    DEFF Research Database (Denmark)

    Schytz, Philip Andreas; Mace, Maria Lerche; Soja, Anne Merete Boas

    2015-01-01

    BACKGROUND: If blood pressure (BP) falls during haemodialysis (HD) [intradialytic hypotension (IDH)] a common clinical practice is to reduce the extracorporeal blood flow rate (EBFR). Consequently the efficacy of the HD (Kt/V) is reduced. However, only very limited knowledge on the effect of redu...

  7. Nonuniform blood flow in the canine left ventricle.

    Science.gov (United States)

    Flynn, A E; Coggins, D L; Austin, R E; Muehrcke, D D; Aldea, G S; Goto, M; Doucette, J W; Hoffman, J I

    1990-11-01

    In order to investigate the relationship between coronary perfusion pressure and blood flow distribution in the left ventricle (LV), we measured myocardial blood flow in small regions using radioactive microspheres in six anesthetized, open-chest dogs. Mean coronary perfusion pressure (CPP) was controlled with a femoral artery to left main coronary artery shunt which included a pressurized, servo-controlled blood reservoir. In each dog, we measured flow in 192 regions of the LV free wall (mean weight per region = 206 +/- 38 mg) at different perfusion pressures. At CPP = 80 mm Hg, blood flow to individual regions varied fourfold (0.30 to 1.18 ml/min/g; relative dispersion (RD) = 21.8 +/- 2.3%). At CPP = 50 mm Hg, flow varied over sevenfold (0.08 to 0.60 ml/min/g; RD = 42.8 +/- 10%; P less than 0.01 vs 80 mm Hg). This relationship between flow variability and CPP was present within individual LV layers as well between layers and is much higher than the error associated with the microsphere technique. We conclude that blood flow to small regions of the LV is markedly nonuniform. This heterogeneity becomes more profound at lower CPP. These findings suggest that (1) global measurements of coronary flow must be interpreted with caution, and (2) even in hearts with normal coronary arteries some regions of the LV are more susceptible to ischemia than others. In addition, these findings may help explain the patchy nature of myocardial damage that occurs following periods of low coronary pressure or inadequate myocardial protection during cardiopulmonary bypass.

  8. Coagulation on biomaterials in flowing blood: some theoretical considerations.

    Science.gov (United States)

    Basmadjian, D; Sefton, M V; Baldwin, S A

    1997-12-01

    Are truly inert biomaterials feasible? Recent mathematical models of coagulation which are reviewed here suggest that such materials are impossible. This conclusion, which is certainly consistent with our collective experimental evidence, arises from the calculation that conversion of Factor XI to XIa never drops to zero even at the highest flow rates and with virtually no Factor XIIa bound to a surface. Residual amounts of XIa are still formed which can in principle kick-off the coagulation cascade. Furthermore, if the flow rates and corresponding mass transfer coefficients are low and in spite of these near-vanishing levels of the initiating coagulants, the surprising result is that substantial amounts of thrombin are produced. On the contrary, under slightly higher flow conditions, there can be more substantial levels of initiating coagulants, yet paradoxically thrombin production is near zero. This article presents a theoretical understanding of the events which take place during the interaction of biomaterials with flowing blood. We follow these events from the time of first contact to the final production of thrombin. The effect of flow and surface activity on the contact phase reactions is examined in detail and the two are found to be intertwined. The common pathway is also examined and here the main feature is the existence of three flow dependent regions which produce either high or very low levels of thrombin, as well as multiple thrombin steady states. In a final analysis we link the two segments of the cascade and consider the events which result. In addition, we note that multiple steady states arise only in the presence of two (thrombin) feedback loops. Single loops or the bare cascade will produce only single steady states. With some imagination one can attribute to the feedback loops the role of providing the cascade with a mechanism to produce high thrombin levels in case of acute need (e.g. bleeding) or to allow levels to subside to 'stand

  9. Flow rate calibration to determine cell-derived microparticles and homogeneity of blood components.

    Science.gov (United States)

    Noulsri, Egarit; Lerdwana, Surada; Kittisares, Kulvara; Palasuwan, Attakorn; Palasuwan, Duangdao

    2017-07-18

    Cell-derived microparticles (MPs) are currently of great interest to screening transfusion donors and blood components. However, the current approach to counting MPs is not affordable for routine laboratory use due to its high cost. The current study aimed to investigate the potential use of flow-rate calibration for counting MPs in whole blood, packed red blood cells (PRBCs), and platelet concentrates (PCs). The accuracy of flow-rate calibration was investigated by comparing the platelet counts of an automated counter and a flow-rate calibrator. The concentration of MPs and their origins in whole blood (n=100), PRBCs (n=100), and PCs (n=92) were determined using a FACSCalibur. The MPs' fold-changes were calculated to assess the homogeneity of the blood components. Comparing the platelet counts conducted by automated counting and flow-rate calibration showed an r(2) of 0.6 (y=0.69x+97,620). The CVs of the within-run and between-run variations of flow-rate calibration were 8.2% and 12.1%, respectively. The Bland-Altman plot showed a mean bias of -31,142platelets/μl. MP enumeration revealed both the difference in MP levels and their origins in whole blood, PRBCs, and PCs. Screening the blood components demonstrated high heterogeneity of the MP levels in PCs when compared to whole blood and PRBCs. The results of the present study suggest the accuracy and precision of flow-rate calibration for enumerating MPs. This flow-rate approach is affordable for assessing the homogeneity of MPs in blood components in routine laboratory practice. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. Investigation of Blood Flow and the Effect of Vasoactive Substances in Cutaneous Blood Vessels of "Xenopus Laevis"

    Science.gov (United States)

    Škorjanc, Aleš; Belušic, Gregor

    2015-01-01

    In the present study, a preparation of frog skin was presented, which can be used to demonstrate the basic concepts of blood flow regulation in a very clear and attractive way to high school and university students. In a freshly euthanized "Xenopus," a patch of abdominal skin was exposed from the internal side and viewed with a USB…

  11. Diagnosis of High Blood Pressure

    Medline Plus

    Full Text Available ... Events Spokespeople Email Alerts E-Newsletters About NHLBI Organization NHLBI Director Budget, Planning, & Legislative Advisory Committees Jobs ... track blood pressure readings over a period of time, the health care provider may ask you to ...

  12. Maximum Likelihood Blood Velocity Estimator Incorporating Properties of Flow Physics

    DEFF Research Database (Denmark)

    Schlaikjer, Malene; Jensen, Jørgen Arendt

    2004-01-01

    The aspect of correlation among the blood velocities in time and space has not received much attention in previous blood velocity estimators. The theory of fluid mechanics predicts this property of the blood flow. Additionally, most estimators based on a cross-correlation analysis are limited...... of simulated and in vivo data from the carotid artery. The estimator is meant for two-dimensional (2-D) color flow imaging. The resulting mathematical relation for the estimator consists of two terms. The first term performs a cross-correlation analysis on the signal segment in the radio frequency (RF......)-data under investigation. The flow physic properties are exploited in the second term, as the range of velocity values investigated in the cross-correlation analysis are compared to the velocity estimates in the temporal and spatial neighborhood of the signal segment under investigation. The new estimator...

  13. Mediators of increased blood flow in porcine skin

    Directory of Open Access Journals (Sweden)

    H. D. Moore

    1992-01-01

    Full Text Available Nicotinates and benzalkonium chloride (B.Cl cause inflammatory changes in human skin, thought to be dependent upon prostaglandin formation. This study has examined the effects of hexyl-nicotinate (HN and B.Cl on blood flow in porcine skin. The role of prostaglandins and interleukin (IL-1 in the blood flow response has been investigated. Blood flow was increased by both HN and B.Cl, the response to B.Cl being more protracted. Cyclooxygenase inhibitor pretreatment reduced these responses. IL-1-like biological activity was identified in normal porcine epidermis and the amounts recovered from inflamed skin were similar. Thus prostaglandin formation in HN or B.Cl-induced inflammation, if IL-1 dependent, is not associated with the loss of significant amounts of the cytokine from the epidermis.

  14. Flow of Red Blood Cells in Stenosed Microvessels

    Science.gov (United States)

    Vahidkhah, Koohyar; Balogh, Peter; Bagchi, Prosenjit

    2016-06-01

    A computational study is presented on the flow of deformable red blood cells in stenosed microvessels. It is observed that the Fahraeus-Lindqvist effect is significantly enhanced due to the presence of a stenosis. The apparent viscosity of blood is observed to increase by several folds when compared to non-stenosed vessels. An asymmetric distribution of the red blood cells, caused by geometric focusing in stenosed vessels, is observed to play a major role in the enhancement. The asymmetry in cell distribution also results in an asymmetry in average velocity and wall shear stress along the length of the stenosis. The discrete motion of the cells causes large time-dependent fluctuations in flow properties. The root-mean-square of flow rate fluctuations could be an order of magnitude higher than that in non-stenosed vessels. Several folds increase in Eulerian velocity fluctuation is also observed in the vicinity of the stenosis. Surprisingly, a transient flow reversal is observed upstream a stenosis but not downstream. The asymmetry and fluctuations in flow quantities and the flow reversal would not occur in absence of the cells. It is concluded that the flow physics and its physiological consequences are significantly different in micro- versus macrovascular stenosis.

  15. Coronary blood flow during cardiopulmonary resuscitation in swine

    Energy Technology Data Exchange (ETDEWEB)

    Bellamy, R.F.; DeGuzman, L.R.; Pedersen, D.C.

    1984-01-01

    Recent papers have raised doubt as to the magnitude of coronary blood flow during closed-chest cardiopulmonary resuscitation. We will describe experiments that concern the methods of coronary flow measurement during cardiopulmonary resuscitation. Nine anesthetized swine were instrumented to allow simultaneous measurements of coronary blood flow by both electromagnetic cuff flow probes and by the radiomicrosphere technique. Cardiac arrest was caused by electrical fibrillation and closed-chest massage was performed by a Thumper (Dixie Medical Inc., Houston). The chest was compressed transversely at a rate of 66 strokes/min. Compression occupied one-half of the massage cycle. Three different Thumper piston strokes were studied: 1.5, 2, and 2.5 inches. Mean aortic pressure and total systemic blood flow measured by the radiomicrosphere technique increased as Thumper piston stroke was lengthened (mean +/- SD): 1.5 inch stroke, 23 +/- 4 mm Hg, 525 +/- 195 ml/min; 2 inch stroke, 33 +/- 5 mm Hg, 692 +/- 202 ml/min; 2.5 inch stroke, 40 +/- 6 mm Hg, 817 +/- 321 ml/min. Both methods of coronary flow measurement (electromagnetic (EMF) and radiomicrosphere (RMS)) gave similar results in technically successful preparations (data expressed as percent prearrest flow mean +/- 1 SD): 1.5 inch stroke, EMF 12 +/- 5%, RMS 16 +/- 5%; 2 inch stroke, EMF 30 +/- 6%, RMS 26 +/- 11%; 2.5 inch stroke, EMF 50 +/- 12%, RMS 40 +/- 20%. The phasic coronary flow signal during closed-chest compression indicated that all perfusion occurred during the relaxation phase of the massage cycle. We concluded that coronary blood flow is demonstrable during closed-chest massage, but that the magnitude is unlikely to be more than a fraction of normal.

  16. Diabetes augments in vivo microvascular blood flow dynamics after stroke.

    Science.gov (United States)

    Tennant, Kelly A; Brown, Craig E

    2013-12-04

    Stroke usually affects people with underlying medical conditions. In particular, diabetics are significantly more likely to have a stroke and the prognosis for recovery is poor. Because diabetes is associated with degenerative changes in the vasculature of many organs, we sought to determine how hyperglycemia affects blood flow dynamics after an ischemic stroke. Longitudinal in vivo two-photon imaging was used to track microvessels before and after photothrombotic stroke in a diabetic mouse model. Chronic hyperglycemia exacerbated acute (3-7 d) ischemia-induced increases in blood flow velocity, vessel lumen diameter, and red blood cell flux in peri-infarct regions. These changes in blood flow dynamics were most evident in superficial blood vessels within 500 μm from the infarct, rather than deeper or more distant cortical regions. Long-term imaging of diabetic mice not subjected to stroke indicated that these acute stroke-related changes in vascular function could not be attributed to complications from hyperglycemia alone. Treating diabetic mice with insulin immediately after stroke resulted in less severe alterations in blood flow within the first 7 d of recovery, but had more variable results at later time points. Analysis of microvessel branching patterns revealed that stroke led to a pruning of microvessels in peri-infarct cortex, with very few instances of sprouting. These results indicate that chronic hyperglycemia significantly affects the vascular response to ischemic stroke and that insulin only partially mitigates these changes. The combination of these acute and chronic alterations in blood flow dynamics could underlie diabetes-related deficits in cortical plasticity and stroke recovery.

  17. Fontan Outcomes and Pulmonary Blood Flow at Birth.

    Science.gov (United States)

    Evans, William N; Acherman, Ruben J; Reardon, Leigh C; Ciccolo, Michael L; Galindo, Alvaro; Rothman, Abraham; Winn, Brody J; Yumiaco, Noel S; Restrepo, Humberto

    2016-01-01

    We previously noted, in a small group of post-Fontan patients, a possible association between hepatic fibrosis scores and the status of pulmonary blood flow at birth. To further explore this observation, we examined data from all Fontan patients seen in our center from July 2010 to March 2015. We identified 200 patients for analysis. Of the 200 patients, 56 underwent transvenous-hepatic biopsy. Of the 200 patients, 13 (6.5%) had protein-losing enteropathy. We divided both the 56 biopsy patients and the entire cohort of 200 patients into 4 groups: (1) unobstructed pulmonary blood flow at birth with functional left ventricles, (2) unobstructed pulmonary blood flow at birth with functional right ventricles, (3) obstructed pulmonary blood flow at birth with functional left ventricles, and (4) obstructed pulmonary blood flow at birth with functional right ventricles. Analysis of the 56 liver-biopsy patient groups showed median hepatic total-fibrosis scores for the 4 groups of 2 (0-6), 2 (0-8), 3 (2-6), and 4 (1-8), respectively, with statistical significance between groups 4 and 1 (p = 0.031). For the entire cohort of 200 patients, we analyzed the incidence of protein-losing enteropathy for each of the four groups and found protein-losing enteropathy percent occurrences of 0, 2.9, 8.8, and 16.1, respectively, with statistical significance between groups 4 and 2 (p = 0.031) and between groups 4 and 1 (p = 0.025). A history of obstructed pulmonary blood flow at birth, coupled with a functional right ventricle, may predict a poorer long-term Fontan outcome.

  18. Effect of increases in cardiac contractility on cerebral blood flow in humans.

    Science.gov (United States)

    Ogoh, Shigehiko; Moralez, Gilbert; Washio, Takuro; Sarma, Satyam; Hieda, Michinari; Romero, Steven A; Cramer, Matthew N; Shibasaki, Manabu; Crandall, Craig G

    2017-09-15

    The effect of acute increases in cardiac contractility on cerebral blood flow (CBF) remains unknown. We hypothesized that the external carotid artery (ECA) downstream vasculature modifies the direct influence of acute increases in heart rate and cardiac function on CBF regulation. Twelve healthy subjects received two infusions of dobutamine (first a low dose; 5 μg/kg/min and then a high dose; 15 μg/kg/min) for 12 min each. Cardiac output, blood flow through the internal carotid artery (ICA) and ECA and echocardiographic measurements were performed during dobutamine infusions. Despite increases in cardiac contractility, cardiac output and arterial pressure with dobutamine, ICA blood flow and conductance slightly decreased from resting baseline during both low and high dose infusions. In contrast, ECA blood flow and conductance increased appreciably during both low and high dose infusions. Greater ECA vascular conductance and corresponding increases in blood flow may protect over-perfusion of intracranial cerebral arteries during enhanced cardiac contractility and associated increases in cardiac output and perfusion pressure. Importantly, these findings suggest that the acute increase of blood perfusion due to dobutamine administration does not cause cerebral over-perfusion or an associated risk of cerebral vascular damage. Copyright © 2017, American Journal of Physiology-Heart and Circulatory Physiology.

  19. Adrenergic influence on gastric mucosal blood flow in gastric fistula dogs

    DEFF Research Database (Denmark)

    Hovendal, C P; Bech, K; Gottrup, F;

    1984-01-01

    by an initial increase in mucosal blood flow and in the last two periods a decrease in blood flow. alpha-Blockade (phentolamine) reduced the pentagastrin stimulated gastric acid secretion and gastric mucosal blood flow but the ratio between blood flow and acid secretion was increased, indicating a relatively...

  20. Low Reynolds number turbulence modeling of blood flow in arterial stenoses.

    Science.gov (United States)

    Ghalichi, F; Deng, X; De Champlain, A; Douville, Y; King, M; Guidoin, R

    1998-01-01

    Moderate and severe arterial stenoses can produce highly disturbed flow regions with transitional and or turbulent flow characteristics. Neither laminar flow modeling nor standard two-equation models such as the kappa-epsilon turbulence ones are suitable for this kind of blood flow. In order to analyze the transitional or turbulent flow distal to an arterial stenosis, authors of this study have used the Wilcox low-Re turbulence model. Flow simulations were carried out on stenoses with 50, 75 and 86% reductions in cross-sectional area over a range of physiologically relevant Reynolds numbers. The results obtained with this low-Re turbulence model were compared with experimental measurements and with the results obtained by the standard kappa-epsilon model in terms of velocity profile, vortex length, wall shear stress, wall static pressure, and turbulence intensity. The comparisons show that results predicted by the low-Re model are in good agreement with the experimental measurements. This model accurately predicts the critical Reynolds number at which blood flow becomes transitional or turbulent distal an arterial stenosis. Most interestingly, over the Re range of laminar flow, the vortex length calculated with the low-Re model also closely matches the vortex length predicted by laminar flow modeling. In conclusion, the study strongly suggests that the proposed model is suitable for blood flow studies in certain areas of the arterial tree where both laminar and transitional/turbulent flows coexist.

  1. Cerebral blood flow and oxidative metabolism during human endotoxemia

    DEFF Research Database (Denmark)

    Møller, Kirsten; Strauss, Gitte Irene; Qvist, Jesper;

    2002-01-01

    The proinflammatory cytokine, tumor necrosis factor-alpha (TNF-alpha), has been suggested to mediate septic encephalopathy through an effect on cerebral blood flow (CBF) and metabolism. The effect of an intravenous bolus of endotoxin on global CBF, metabolism, and net flux of cytokines...... and catecholamines was investigated in eight healthy young volunteers. Cerebral blood flow was measured by the Kety-Schmidt technique at baseline (during normocapnia and voluntary hyperventilation for calculation of subject-specific cerebrovascular CO reactivity), and 90 minutes after an intravenous bolus...

  2. Disparity in regional cerebral blood flow during electrically induced seizure

    DEFF Research Database (Denmark)

    Sestoft, D; Meden, P; Hemmingsen, R

    1993-01-01

    This is a presentation of 2 cases in which the intraictal regional cerebral blood flow distribution was measured with the 99mTc-HMPAO single photon emission computerized tomography technique during an electrically induced seizure. Although the seizure was verified as generalized on electroencepha......This is a presentation of 2 cases in which the intraictal regional cerebral blood flow distribution was measured with the 99mTc-HMPAO single photon emission computerized tomography technique during an electrically induced seizure. Although the seizure was verified as generalized...... electroencephalography-verified generalized seizures....

  3. Reduced blood flow to contracting skeletal muscle in ageing humans

    DEFF Research Database (Denmark)

    Nyberg, Michael Permin; Hellsten, Ylva

    2016-01-01

    consequences of ageing and physical inactivity can be challenging; yet, observations from cross-sectional and longitudinal studies on the effects of physical activity have provided some insight. Physical activity has the potential to offset the age-related decline in blood flow to contracting skeletal muscle...... and the ability for functional sympatholysis; an attenuation of the vasoconstrictor effect of sympathetic nervous activity. These vascular adaptations with physical activity are likely to be an effect of improved nitric oxide and ATP signaling. Collectively, precise matching of blood flow and O2 delivery to meet...

  4. Splanchnic blood flow and hepatic glucose production in exercising humans

    DEFF Research Database (Denmark)

    Bergeron, R; Kjaer, M; Simonsen, L

    2001-01-01

    The study examined the implication of the renin-angiotensin system (RAS) in regulation of splanchnic blood flow and glucose production in exercising humans. Subjects cycled for 40 min at 50% maximal O(2) consumption (VO(2 max)) followed by 30 min at 70% VO(2 max) either with [angiotensin......-blockade group vs. the control group, hormones, metabolites, VO(2), and RER followed the same pattern of changes in ACE-blockade and control groups during exercise. Splanchnic blood flow (at rest: 1.67 +/- 0.12, ACE blockade; 1.59 +/- 0.18 l/min, control) decreased during moderate exercise (0.78 +/- 0.07, ACE...

  5. Improved technique for blood flow velocity measurement using Doppler effect

    Science.gov (United States)

    Valadares Oliveira, Eduardo J.; Nantes Button, Vera L. d. S.; Maia, Joaquim M.; Costa, Eduardo T.

    2002-04-01

    The Doppler velocimeter developed allows to determine the angle between the ultrasonic beam and the velocity vector of the flow, and to calculate the precise blood flow in a vessel. Four piezoelectric transducers constitute the Doppler velocimeter. Three of these transducers are positioned to form an equilateral triangle (base of a pyramid). When these transducers move simultaneously, backward or forward from the initial position, the emitted ultrasonic beams focalize on a position (peak of the pyramid) closer or farther from the transducers faces, according to the depth of the vessel where we intend to measure de flow. The angle between the transducers allows adjusting the height of this pyramid and the position of the focus (where the three beams meet). A forth transducer is used to determine the diameter of the vessel and monitor the position of the Doppler velocimeter relative to the vessel. Simulation results showed that with this technique is possible to accomplish precise measurement of blood flow.

  6. Spring-network-based model of a red blood cell for simulating mesoscopic blood flow.

    Science.gov (United States)

    Nakamura, Masanori; Bessho, Sadao; Wada, Shigeo

    2013-01-01

    We developed a mechanical model of a red blood cell (RBC) that is capable of expressing its characteristic behaviors in shear flows. The RBC was modeled as a closed shell membrane consisting of spring networks in the framework of the energy minimum concept. The fluid forces acting on RBCs were modeled from Newton's viscosity law and the conservation of momentum. In a steady shear flow, the RBC model exhibited various behaviors, depending on the shear rate; it tumbled, tank-treaded, or both. The transition from tumbling to tank-treading occurred at a shear rate of 20 s( - 1). The simulation of an RBC in steady and unsteady parallel shear flows (Couette flows) showed that the deformation parameters of the RBC were consistent with experimental results. The RBC in Poiseuille flow migrated radially towards the central axis of the flow channel. Axial migration became faster with an increase in the viscosity of the media, qualitatively consistent with experimental results. These results demonstrate that the proposed model satisfies the essential conditions for simulating RBC behavior in blood flow. Finally, a large-scale RBC flow simulation was implemented to show the capability of the proposed model for analyzing the mesoscopic nature of blood flow.

  7. SAFETY CONSIDERATIONS WITH BLOOD FLOW RESTRICTED RESISTANCE TRAINING

    Directory of Open Access Journals (Sweden)

    Alan Kacin

    2015-11-01

    Full Text Available Blood flow restricted resistance (BFRR training with pneumatic tourniquet has been suggested as an alternative for conventional weight training due to the proven benefits for muscle strength and hypertrophy using relatively low resistance, hence reducing the mechanical stress across a joint. As such, it has become an important part of rehabilitation programs used in either injured or operated athletes. Despite a general consensus on effectiveness of BFRR training for muscle conditioning, there are several uncertainties regarding the interplay of various extrinsic and intrinsic factors on its safety and efficiency, which are being reviewed from a clinical perspective. Among extrinsic factors tourniquet cuff pressure, size and shape have been identified as key for safety and efficiency. Among intrinsic factors, limb anthropometrics, patient history and presence of cardiac, vascular, metabolic or peripheral neurologic conditions have been recognized as most important. Though there are a few potential safety concerns connected to BFRR training, the following have been identified as the most probable and health-hazardous: (a mechanical injury to the skin, muscle, and peripheral nerves, (b venous thrombosis due to vascular damage and disturbed hemodynamics and (c augmented arterial blood pressure responses due to combined high body exertion and increased peripheral vascular resistance. Based on reviewed literature and authors’ personal experience with the use of BFRR training in injured athletes, some guidelines for its safe application are outlined. Also, a comprehensive risk assessment tool for screening of subjects prior to their inclusion in a BFRR training program is being introduced.

  8. The vascular response observation by the monitoring of the photosensitizer, oxygen, and blood flow during the high intensity pulsed excitation photodynamic therapy 1h after water-soluble photosensitizer intravenous injection

    Science.gov (United States)

    Hakomori, S.; Matsuo, H.; Arai, T.

    2008-02-01

    We investigated the correlation between the therapeutic effect by early irradiation Photodynamic Therapy (PDT) and vascular response. The early irradiation PDT has been proposed by our group. This PDT protocol is that pulse laser irradiates to tumors 1 h after intravenous injection of water-soluble photosensitizer. The intact layer appeared over the well treated layer, when the early irradiation PDT was performed at rat prostate subcutaneous tumors with high intensity pulse laser (over 1 MW/cm2 in peak intensity) and Talaporfin sodium. In order to clarify the phenomenon mechanism, we monitored blood volume, surface temperature, photosensitizer amount, and oxygen saturation during the PDT. The rat prostate subcutaneous tumor was irradiated with excimer dye laser light at 1 h after the intravenous injection. The photosensitizer dose wa 2.0 mg/kg, and the pulse energy density was 2.5 mJ/cm2 (low intensity) or 10 mJ/cm2 (high intensity). Under the low intensity pulsed PDT, the fluorescence amount was decreasing gently during the irradiation, and the blood volume and oxygen saturation started decreasing just after the irradiation. Under the hgh intensity pulsed PDT, the fluorescence amount was decreaased rapidly for 20 s after the irradiation started. The blood volume and oxygen saturation were temporally decreased during the irradiation, and recovered at 48 hrs after the irradiation. According to these results, under the low intensity pulsed PDT, the blood vessel located near the surface started closing just after the irradiation. On the other hand, under the high intensity pulsed PDT the blood vessel was closing for 20 s after the irradiation started, moreover, the blood flow recovered at 48 hrs after the irradiation. We concluded that the vascular response depended on the pulse energy density, and then the therapeutic effect was attributed to the difference of the vascular response. In other words, the surface intact layer could be considered to be induced the

  9. Doppler standard deviation imaging for clinical monitoring of in vivo human skin blood flow

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Yonghua; Chen, Zhongping; Saxer, Christopher; Shen, Qimin; Xiang, Shaohua; Boer, Johannes F. de; Nelson, J. Stuart

    2000-09-15

    We used a novel phase-resolved optical Doppler tomographic (ODT) technique with very high flow-velocity sensitivity (10 {mu}m/s) and high spatial resolution (10 {mu}m) to image blood flow in port-wine stain (PWS) birthmarks in human skin. In addition to the regular ODT velocity and structural images, we use the variance of blood flow velocity to map the PWS vessels. Our device combines ODT and therapeutic systems such that PWS blood flow can be monitored in situ before and after laser treatment. To the authors' knowledge this is the first clinical application of ODT to provide a fast semiquantitative evaluation of the efficacy of PWS laser therapy in situ and in real time. (c) 2000 Optical Society of America.

  10. Doppler Assessment of Uterine Blood Flow in Recurrent Pregnancy Loss

    Directory of Open Access Journals (Sweden)

    Maryam Barzin

    2011-05-01

    Full Text Available Recurrent spontaneous abortion affects 2%-5% of"ncouples. Uterine perfusion is considered as one of the"nfactors that influences the success of implantation."nDuring the normal menstrual cycle, the impedance"nto uterine artery blood flow diminishes progressively"nduring the luteal phase, reaching the lowest values"nin the period coinciding with the implantation time."nImpedance of uterine arteries is a good indicator of"nthe possibility of a subsequent pregnancy. High blood"nflow resistance is associated with a reduced conception"nrate and women with lower pulsatility index values"nhave the highest possibility of becoming pregnant. An"nimpaired uterine perfusion could play a major role in"nthe pathogenesis of recurrent spontaneous abortion. In"nthis study, we examined sixty women with recurrent"nspontaneous abortion and a control group including"nthirty normal women with at least one previous"nuncomplicated pregnancy and without history of any"nabortion. Transvaginal sonography associated with"nDoppler flow measurement was performed during"nthe midluteal phase of a cycle in all women. The"nmeasurement of the ascending branch of both right"nand left uterine arteries was taken lateral to the cervix"nat the level of the internal os. The pulsatility and"nresistance index of both uterine arteries were calculated"nand compared in both groups. In this presentation we"nreport our finding in two groups. We also explain the"nexact method of study and present some interesting"ncases

  11. Spatial heterogeneity of blood flow in the dog heart. II. Temporal stability in response to adrenergic stimulation.

    Science.gov (United States)

    Deussen, A; Flesche, C W; Lauer, T; Sonntag, M; Schrader, J

    1996-07-01

    The effects of adrenergic stimulation on local myocardial blood flow in the left ventricle were studied in 13 anaesthetized Beagle dogs using the tracer microsphere technique. Adrenergic stimulation was induced by intravenous infusion of orciprenaline (1-2 microg kg-1 min-1) over 15 min or by electrical stimulation of the left ansa subclavia (10 Hz, 1 ms, 4-8 V) over 5 min. Local myocardial blood flow was analysed in 256 samples with an average (+/-SD) mass of 318+/-49 mg from the left ventricular myocardium using a standardized dissection procedure. Orciprenaline increased the average myocardial blood flow from 0.85+/-0.18 to 1.73+/-0.27 ml min-1 g-1, while oxygen consumption and the pressure-rate product increased by 129 and 119% respectively. The coefficients of variation of local myocardial blood flow, a measure of spatial blood flow heterogeneity, were 0.21 and 0.18 under control and orciprenaline respectively. Except for a slight transmural gradient (endomyocardium/epimyocardium flow ratio 1.19) myocardial blood flow did not exhibit significant spatial gradients. Stimulation with orciprenaline increased the average blood flow in all regions of the left ventricle by comparable extents. However, local blood flow during orciprenaline was significantly lower in samples from regions which had a lower blood flow under resting control conditions. A significant positive relationship was obtained between local myocardial blood flow under resting conditions and orciprenaline (r=0.45+/-0.18). Moreover, after recovery from orciprenaline stimulation (i.e. 40-112 min after the end of orciprenaline infusion) local myocardial blood flow exhibited a high degree of correlation with local flow before orciprenaline (r=0.71+/-0.08). Comparable results were obtained with electrical stimulation of the left ansa subclavia. For the comparison stimulation vs. control, the correlation coefficient of local blood flow was 0.52+/-0.04 and for recovery vs. control 0.77+/-0.06. From these

  12. Measurement of cerebral blood flow using phase contrast magnetic resonance imaging and duplex ultrasonography.

    Science.gov (United States)

    Khan, Muhammad Ayaz; Liu, Jie; Tarumi, Takashi; Lawley, Justin Stevan; Liu, Peiying; Zhu, David C; Lu, Hanzhang; Zhang, Rong

    2017-02-01

    Phase contrast magnetic resonance imaging (PC-MRI) and color-coded duplex ultrasonography (CDUS) are commonly used for measuring cerebral blood flow in the internal carotid (ICA) and vertebral arteries. However, agreement between the two methods has been controversial. Recent development of high spatial and temporal resolution blood vessel wall edge-detection and wall-tracking methods with CDUS increased the accuracy and reliability of blood vessel diameter, hence cerebral blood flow measurement. The aim of this study was to compare the improved CDUS method with 3 T PC-MRI for cerebral blood flow measurements. We found that cerebral blood flow velocity measured in the ICA was lower using PC-MRI than CDUS (left ICA: PC-MRI, 18.0 ± 4.2 vs. CDUS, 25.6 ± 8.6 cm/s; right ICA: PC-MRI, 18.5 ± 4.8 vs. CDUS, 26.6 ± 6.7 cm/s, both p blood flow velocity measured in the left vertebral artery with PC-MRI was also lower than CDUS, but no differences in vertebral artery diameter were observed between the methods. Dynamic changes and/or intrinsic physiological fluctuations may have caused these differences in vessel diameter and velocity measurements between the methods. However, estimation of volumetric cerebral blood flow was similar and correlated between the methods despite the presence of large individual differences. These findings support the use of CDUS for cerebral blood flow measurements in the ICA and vertebral artery.

  13. Amino Acids That Centrally Influence Blood Pressure and Regional Blood Flow in Conscious Rats

    Directory of Open Access Journals (Sweden)

    Yumi Takemoto

    2012-01-01

    Full Text Available Functional roles of amino acids have increasingly become the focus of research. This paper summarizes amino acids that influence cardiovascular system via the brain of conscious rats. This paper firstly describes why amino acids are selected and outlines how the brain regulates blood pressure and regional blood flow. This section includes a concise history of amino acid neurotransmitters in cardiovascular research and summarizes brain areas where chemical stimulations produce blood pressure changes mainly in anesthetized animals. This is followed by comments about findings regarding several newly examined amino acids with intracisternal stimulation in conscious rats that produce changes in blood pressure. The same pressor or depressor response to central amino acid stimulations can be produced by distinct mechanisms at central and peripheral levels, which will be briefly explained. Thereafter, cardiovascular actions of some of amino acids at the mechanism level will be discussed based upon findings of pharmacological and regional blood flow measurements. Several examined amino acids in addition to the established neurotransmitter amino acids appear to differentially activate brain structures to produce changes in blood pressure and regional blood flows. They may have physiological roles in the healthy brain, but pathological roles in the brain with cerebral vascular diseases such as stroke where the blood-brain barrier is broken.

  14. Dramatic Increase in Cerebral Blood Flow following Soman Intoxication If Signs of Symptoms Can Be Seen

    Directory of Open Access Journals (Sweden)

    Ann Göransson Nyberg

    2015-01-01

    Full Text Available Organophosphate poisoning is associated with adverse effects on the central nervous system such as seizure/convulsive activity and long term changes in neuronal networks. This study report an investigation designed to assess the consequences of Soman, a highly toxic organophosphorus compound, exposure on regional blood flow in the rat brain and peripheral organs. We performed repeated blood flow measurements in the same animal, using the microspheres technique, to characterize changes in regional blood flow at different times after Soman intoxication. In addition, the cardiopulmonary effects of Soman were followed during the intoxication. Administration of Soman (1 LD50; 90 µg/kg, s.c. to anaesthetized rats produced a decrease in blood acetylcholinesterase activity in all animals tested. Although, only six out of ten rats showed signs of poisoning like a decrease in respiratory rate, the results show that only animals with significant signs of poisoning demonstrated an increase in cerebral blood flow. We conclude that it is of great importance to treat all data individually. An overall mean can easily be misinterpreted and conceal important effects. We also conclude that the increase in cerebral blood flow has an important role in the effect on respiration and that this effect is independent of the blood acetylcholinesterase activity.

  15. Luteal blood flow in patients undergoing GnRH agonist long protocol

    Directory of Open Access Journals (Sweden)

    Takasaki Akihisa

    2011-01-01

    Full Text Available Abstract Background Blood flow in the corpus luteum (CL is closely related to luteal function. It is unclear how luteal blood flow is regulated. Standardized ovarian-stimulation protocol with a gonadotropin-releasing hormone agonist (GnRHa long protocol causes luteal phase defect because it drastically suppresses serum LH levels. Examining luteal blood flow in the patient undergoing GnRHa long protocol may be useful to know whether luteal blood flow is regulated by LH. Methods Twenty-four infertile women undergoing GnRHa long protocol were divided into 3 groups dependent on luteal supports; 9 women were given ethinylestradiol plus norgestrel (Planovar orally throughout the luteal phase (control group; 8 women were given HCG 2,000 IU on days 2 and 4 day after ovulation induction in addition to Planovar (HCG group; 7 women were given vitamin E (600 mg/day orally throughout the luteal phase in addition to Planovar (vitamin E group. Blood flow impedance was measured in each CL during the mid-luteal phase by transvaginal color-pulsed-Doppler-ultrasonography and was expressed as a CL-resistance index (CL-RI. Results Serum LH levels were remarkably suppressed in all the groups. CL-RI in the control group was more than the cutoff value (0.51, and only 2 out of 9 women had CL-RI values Conclusion Patients undergoing GnRHa long protocol had high luteal blood flow impedance with very low serum LH levels. HCG administration improved luteal blood flow impedance. This suggests that luteal blood flow is regulated by LH.

  16. [Effect of preoperative administration of Lugol's solution on thyroid blood flow in hyperthyroidism].

    Science.gov (United States)

    Rodier, J F; Janser, J C; Petit, H; Schneegans, O; Ott, G; Kaissling, A; Grob, J C; Velten, M

    1998-01-01

    A study of 50 patients with hyperthyroidism was conducted to evaluate the effect of preoperative administration of Lugol's iodine solution on thyroid blood flow. Highly significant reductions in diameter, time-averaged velocity, and volume flow of the superior thyroid artery were demonstrated after administration of Lugol's solution. The Duplex ultrasound scanning used in this study is a noninvasive, inexpensive, accurate, and reproducible technique suitable for analysis of thyroid blood flow in hyperthyroidism. On the basis of current ultrasonographic results and low postoperative morbidity in patients, Lugol's solution is well tolerated and may be recommended for use before thyroidectomy, especially for diffuse toxic goiters and Graves disease.

  17. Simulation of Blood Flow at Vessel Bifurcation by Lattice Boltzmann Method

    Science.gov (United States)

    Kang, Xiu-Ying; Liu, Da-He; Zhou, Jing; Jin, Yong-Juan

    2005-11-01

    The application of the lattice Boltzmann method to the large vessel bifurcation blood flow is investigated in a wide range of Reynolds numbers. The velocity, shear stress and pressure distributions at the bifurcation are presented in detail. The flow separation zones revealed with increase of Reynolds number are located in the areas of the daughter branches distal to the outer corners of the bifurcation where some deposition of particular blood components might occur to form arteriosclerosis. The results also demonstrate that the lattice Boltzmann method is adaptive to simulating the flow in larger vessels under a high Reynolds number.

  18. Age and gender related differences in aortic blood flow

    Science.gov (United States)

    Enevoldsen, Marie Sand; Pedersen, Mads Møller; Hemmsen, Martin Christian; Lönn, Lars; Henneberg, Kaj-Åge; Jensen, Jørgen Arendt

    2012-03-01

    The abdominal aorta (AA) is predisposed to development of abdominal aneurysms (AAA), a focal dilatation with fatal consequences if left untreated. The blood flow patterns is thought to play an important role in the development of AAA. The purpose of this work is to investigate the blood flow patterns within a group of healthy volunteers (six females, eight males) aged 23 to 76 years to identify changes and differences related to age and gender. The healthy volunteers were categorized by gender (male/female) and age (below/above 35 years). Subject-specific flow and geometry data were acquired using the research interface on a Profocus ultrasound scanner (B-K Medical, Herlev, Denmark; segmentation of 3D magnetic resonance angiography (Magnetom Trio, Siemens Healthcare, Erlangen, Germany). The largest average diameter was among the elderly males (19.7 (+/- 1.33) mm) and smallest among the young females (12.4 (+/- 0.605) mm). The highest peak systolic velocity was in the young female group (1.02 (+/- 0.336) m/s) and lowest in the elderly male group (0.836 (+/- 0.127) m/s). A geometrical change with age was observed as the AA becomes more bended with age. This also affects the blood flow velocity patterns, which are markedly different from young to elderly. Thus, changes in blood flow patterns in the AA related to age and gender are observed. Further investigations are needed to determine the relation between changes in blood flow patterns and AAA development.

  19. Diagnosis of High Blood Pressure

    Medline Plus

    Full Text Available ... Technology Transfer Clinical Trials What Are Clinical Trials? Children & Clinical Studies NHLBI Trials Clinical Trial Websites News & ... are consistently higher than 120/80 mmHg. Your child’s blood pressure numbers are outside average numbers for ...

  20. Diagnosis of High Blood Pressure

    Medline Plus

    Full Text Available ... Related Topics Atherosclerosis DASH Eating Plan Overweight and Obesity Smoking and Your Heart Stroke Send a link ... are consistently higher than 120/80 mmHg. Your child’s blood pressure numbers are outside average numbers for ...

  1. [Measurement of cerebral blood flow by thermal diffusion using a flow probe with a Peltier stack].

    Science.gov (United States)

    Yamagata, S; Kikuchi, H; Hashimoto, K; Minamikawa, J; Watanabe, Y

    1987-05-01

    In order to evaluate the blood flow by means of thermal diffusion, relationship between blood flow and parameters induced by thermal diffusion was investigated. Flow probe employed for measurement by thermal diffusion incorporated a Peltier stack which contained a small semiconductor and two L-shaped gold plates. These two plates were attached to both sides of the semiconductor by one side of each gold plate and the other side was surfaced with a tissue to be measured. Temperature gradient is created with current applied to the Peltier stack between two plates, one cooled and the other heated, and it is affected only by tissue blood flow. Two kinds of parameters of thermal diffusion were subjected to compare to blood flow. One was temperature gradient when the constant current was applied to the Peltier stack. The other was a current required to maintain a definite temperature gradient which was determined before hand. From the theoretical principle in thermodynamics, the correlations between blood flow and each of thermal diffusion parameters were defined by the following equations: (Formula: see text) where F is blood flow, delta V is voltage converted from temperature gradient, and Ci and Cv are constants. Each of phi v and phi i indicates the characteristics of each probe. Experimental study was carried out to confirm the above relationship using cortex of experimental animals. Under the general anesthesia, a cat was placed in prone position. After the craniotomy, dura mater was opened and a small flow probe, 10 mm in diameter, 5 mm in height and 5 g in weight, was placed on the cortex and blood flow was continuously evaluated by two parameters.(ABSTRACT TRUNCATED AT 250 WORDS)

  2. Development of a miniature intraventricular axial flow blood pump.

    Science.gov (United States)

    Yamazaki, K; Umezu, M; Koyanagi, H; Outa, E; Ogino, S; Otake, Y; Shiozaki, H; Fujimoto, T; Tagusari, O; Kitamura, M

    1993-01-01

    A new intraventricular axial flow blood pump has been designed and developed as a totally implantable left ventricular assist device (LVAD). This pump consists of an impeller combined with a guide-vane, a tube housing, and a DC motor. The pump is introduced into the LV cavity through the LV apex, and the outlet cannula is passed antegrade across the aortic valve. Blood is withdrawn from the LV through the inlet ports at the pump base, and discharged to the ascending aorta. Our newly developed axial flow pump system has the following advantages: 1) it is a simple and compact system, 2) minimal blood stasis both in the device and the LV cavity, 3) minimal blood contacting surface of the pump, 4) easy accessibility with a less invasive surgical procedure, and 5) low cost. A pump flow > 5 L/min was obtained against 100 mmHg differential pressure in the mock circulatory system. The pump could produce a passive pulsatile flow effect with a beating heart more efficiently than other non-pulsatile pumps because of minimal pressure drop and inertia along the bypass tract. Anatomic fit studies using dissected hearts of dilated cardiomyopathy (DCM) cadavers showed that this pump could smoothly pass through the aortic valve without any interference with mitral valve function. Recently, a dynamic pressure groove bearing and a miniature lip seal have been developed. The dynamic pressure groove bearing has a simple structure and acts as a pressure resistant sealing mechanism.(ABSTRACT TRUNCATED AT 250 WORDS)

  3. Vasodilator interactions in skeletal muscle blood flow regulation

    DEFF Research Database (Denmark)

    Hellsten, Ylva; Nyberg, Michael Permin; Jensen, Lasse Gliemann;

    2012-01-01

    that this remaining hyperemia may be explained by cAMP and cGMP independent smooth muscle relaxation, such as effects of endothelial derived hyperpolarization factors (EDHFs) or through metabolic modulation of sympathetic effects. The nature and role of EDHF as well as potential novel mechanisms in muscle blood flow...

  4. CHARACTERIZATION OF RENAL BLOOD FLOW REGULATION BASED ON WAVELET COEFFICIENTS

    DEFF Research Database (Denmark)

    Pavlov, A.N.; Pavlova, O.N.; Mosekilde, Erik

    2010-01-01

    The purpose of this study is to demonstrate the possibility of revealing new characteristic features of renal blood flow autoregulation in healthy and pathological states through the application of discrete wavelet transforms to experimental time series for normotensive and hypertensive rats...

  5. A New Technology for Detecting Cerebral Blood Flow

    DEFF Research Database (Denmark)

    Schytz, Henrik W; Guo, Song; Jensen, Lars T

    2012-01-01

    There is a need for real-time non-invasive, continuous monitoring of cerebral blood flow (CBF) during surgery, in intensive care units and clinical research. We investigated a new non-invasive hybrid technology employing ultrasound tagged near infrared spectroscopy (UT-NIRS) that may estimate...

  6. Cerebral blood flow response to propranolol in streptozotocin diabetic rats

    DEFF Research Database (Denmark)

    Lass, Preben; Knudsen, G M

    1990-01-01

    The influence of propranolol on cerebral blood flow (CBF) was tested in streptozotocin diabetic rats and in control animals. Resting CBF values were 40% lower in the diabetic rats compared with controls. Intravenous injection of propranolol (2 mg kg-1) decreased CBF significantly in the control...

  7. Influence of blood flow on the coagulation cascade

    DEFF Research Database (Denmark)

    The influence of diffusion and convetive flows on the blood coagulation cascade is investigated for a controlled perfusion experiment. We present a cartoon model and reaction schemes for parts of the coagulation cascade with sunsequent set up of a mathematical model in two space dimensions plus one...

  8. Patterns of regional cerebral blood flow in acute stroke

    DEFF Research Database (Denmark)

    Olsen, T S; Skriver, E B

    1981-01-01

    In a consecutive group of 56 stroke patients the regional cerebral blood flow was measured within 84 hours after stroke. A 254 multidetector scintillation camera and the intracarotid Xenon-133 injection method was used to study rCBF. Typical rCBF-patterns are described and compared to the findings...

  9. Longitudinal Cerebral Blood Flow Changes during Speech in Hereditary Ataxia

    Science.gov (United States)

    Sidtis, John J.; Strother, Stephen C.; Naoum, Ansam; Rottenberg, David A.; Gomez, Christopher

    2010-01-01

    The hereditary ataxias constitute a group of degenerative diseases that progress over years or decades. With principal pathology involving the cerebellum, dysarthria is an early feature of many of the ataxias. Positron emission tomography was used to study regional cerebral blood flow changes during speech production over a 21 month period in a…

  10. Increased cerebral blood flow in preeclampsia with magnetic resonance imaging

    NARCIS (Netherlands)

    Zeeman, GG; Hatab, MR; Twickler, DM

    2004-01-01

    Objective: The purpose of this study was to compare third trimester and nonpregnant cerebral blood flow of women with preeclampsia to normotensive control subjects with the use of magnetic resonance imaging techniques. Study design: Nine normotensive pregnant women and 12 untreated women with preecl

  11. Metabolic control of muscle blood flow during exercise in humans

    DEFF Research Database (Denmark)

    Boushel, Robert Christopher

    2003-01-01

    During muscle contraction, several mechanisms regulate blood flow to ensure a close coupling between muscle oxygen delivery and metabolic demand. No single factor has been identified to constitute the primary metabolic regulator, yet there are signal transduction pathways between skeletal muscle...

  12. Disparity in regional cerebral blood flow during electrically induced seizure

    DEFF Research Database (Denmark)

    Sestoft, D; Meden, P; Hemmingsen, R

    1993-01-01

    This is a presentation of 2 cases in which the intraictal regional cerebral blood flow distribution was measured with the 99mTc-HMPAO single photon emission computerized tomography technique during an electrically induced seizure. Although the seizure was verified as generalized on electroencepha...

  13. Renal blood flow in experimental septic acute renal failure

    NARCIS (Netherlands)

    Langenberg, C.; Wan, L.; Egi, M.; May, C. N.; Bellomo, R.

    2006-01-01

    Reduced renal blood flow (RBF) is considered central to the pathogenesis of septic acute renal failure (ARF). However, no controlled experimental studies have continuously assessed RBF during the development of severe septic ARF. We conducted a sequential animal study in seven female Merino sheep. F

  14. Nocturnal foot blood flow in patients with arterial insufficiency

    DEFF Research Database (Denmark)

    Jelnes, Rolf; Tønnesen, K H

    1984-01-01

    was on average the same in patients with normal circulations and in patients with different degrees of arterial insufficiency (mean: 2.0 +/- 0.8 ml min-1 100 g-1). During sleep the blood flow nearly doubled in patients with normal circulations; no systematic change was seen in patients with intermittent...

  15. Longitudinal Cerebral Blood Flow Changes during Speech in Hereditary Ataxia

    Science.gov (United States)

    Sidtis, John J.; Strother, Stephen C.; Naoum, Ansam; Rottenberg, David A.; Gomez, Christopher

    2010-01-01

    The hereditary ataxias constitute a group of degenerative diseases that progress over years or decades. With principal pathology involving the cerebellum, dysarthria is an early feature of many of the ataxias. Positron emission tomography was used to study regional cerebral blood flow changes during speech production over a 21 month period in a…

  16. [Measurement of cerebral blood flow using phase-contrast MRI].

    Science.gov (United States)

    Obata, T; Shishido, F; Koga, M; Ikehira, H; Kimura, F; Yoshida, K

    1997-07-01

    The development of phase-contrast magnetic resonance imaging(P-C MRI) provides a noninvasive method for measurement of volumetric blood flow(VFR). The VFR of the left and right internal carotid arteries and basilar artery were measured using P-C MRI, and total cerebral blood flow(tCBF) was calculated by summing up the VFR values in three vessels. We investigated the changes in these blood flows as influenced from age, head size, height, weight, body surface area and handedness. Moreover, regional CBF(rCBF) was measured by combining with the single photon emission computed tomography(SPECT) of 123I. The blood flows were 142 +/- 58 mL/ min(mean +/- SD) in the basilar artery, 229 +/- 86 mL/min in the left, 223 +/- 58 mL/min in the right internal carotid artery, and tCBF was 617 +/- 128 mL/min(Ref. Magn Resn Imaging 14:P. 1143, 1996). Significant increases were observed in head-size-related change of VFR in the basilar artery and height-related change of tCBF. The value of rCBF was easily acquired in combination with SPECT. Phase-contrast MRI is useful for a noninvasive and rapid analysis of cerebral VFR and has potential for clinical use.

  17. A VARIATIONAL MODEL FOR 2-D MICROPOLAR BLOOD FLOW

    Institute of Scientific and Technical Information of China (English)

    He Ji-huan

    2003-01-01

    The micropolar fluid model is an essential generalization of the well-established Navier-Stokes model in the sense that it takes into account the microstructure of the fluid.This paper is devolted to establishing a variational principle for 2-D incompressible micropolar blood flow.

  18. Coded ultrasound for blood flow estimation using subband processing

    DEFF Research Database (Denmark)

    Gran, F.; Udesen, J.; Jensen, J.A.;

    2008-01-01

    This paper investigates the use of coded excitation for blood flow estimation in medical ultrasound. Traditional autocorrelation estimators use narrow-band excitation signals to provide sufficient signal-to-noise-ratio (SNR) and velocity estimation performance. In this paper, broadband coded sign...

  19. 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.

  20. Whole-body vibration dosage alters leg blood flow.

    NARCIS (Netherlands)

    Lythgo, N.; Eser, P.; Groot, P.C.E. de; Galea, M.

    2009-01-01

    The effect of whole-body vibration dosage on leg blood flow was investigated. Nine healthy young adult males completed a set of 14 random vibration and non-vibration exercise bouts whilst squatting on a Galileo 900 plate. Six vibration frequencies ranging from 5 to 30 Hz (5 Hz increments) were used

  1. Whole-body vibration dosage alters leg blood flow

    NARCIS (Netherlands)

    Lythgo, Noel; Eser, Prisca; de Groot, Patricia; Galea, Mary

    The effect of whole-body vibration dosage on leg blood flow was investigated. Nine healthy young adult males completed a set of 14 random vibration and non-vibration exercise bouts whilst squatting on a Galileo 900 plate. Six vibration frequencies ranging from 5 to 30 Hz (5 Hz increments) were used

  2. Brain energy metabolism and blood flow differences in healthy aging

    DEFF Research Database (Denmark)

    Aanerud, Joel; Borghammer, Per; Chakravarty, M Mallar

    2012-01-01

    Cerebral metabolic rate of oxygen consumption (CMRO(2)), cerebral blood flow (CBF), and oxygen extraction fraction (OEF) are important indices of healthy aging of the brain. Although a frequent topic of study, changes of CBF and CMRO(2) during normal aging are still controversial, as some authors...

  3. Ultrasonic Doppler blood flow meter for extracorporeal circulation

    Science.gov (United States)

    Dantas, Ricardo G.; Costa, Eduardo T.; Maia, Joaquim M.; Nantes Button, Vera L. d. S.

    2000-04-01

    In cardiac surgeries it is frequently necessary to carry out interventions in internal heart structures, and where the blood circulation and oxygenation are made by artificial ways, out of the patient's body, in a procedure known as extracorporeal circulation (EC). During this procedure, one of the most important parameters, and that demands constant monitoring, is the blood flow. In this work, an ultrasonic pulsed Doppler blood flowmeter, to be used in an extracorporeal circulation system, was developed. It was used a 2 MHz ultrasonic transducer, measuring flows from 0 to 5 liters/min, coupled externally to the EC arterial line destined to adults perfusion (diameter of 9.53 mm). The experimental results using the developed flowmeter indicated a maximum deviation of 3.5% of full scale, while the blood flow estimator based in the rotation speed of the peristaltic pump presented deviations greater than 20% of full scale. This ultrasonic flowmeter supplies the results in a continuous and trustworthy way, and it does not present the limitations found in those flowmeters based in other transduction methods. Moreover, due to the fact of not being in contact with the blood, it is not disposable and it does not need sterilization, reducing operational costs and facilitating its use.

  4. Noninvasive pulsatile flow estimation for an implantable rotary blood pump.

    Science.gov (United States)

    Karantonis, Dean M; Cloherty, Shaun L; Mason, David G; Ayre, Peter J; Lovell, Nigel H

    2007-01-01

    A noninvasive approach to the task of pulsatile flow estimation in an implantable rotary blood pump (iRBP) has been proposed. Employing six fluid solutions representing a range of viscosities equivalent to 20-50% blood hematocrit (HCT), pulsatile flow data was acquired from an in vitro mock circulatory loop. The entire operating range of the pump was examined, including flows from -2 to 12 L/min. Taking the pump feedback signals of speed and power, together with the HCT level, as input parameters, several flow estimate models were developed via system identification methods. Three autoregressive with exogenous input (ARX) model structures were evaluated: structures I and II used the input parameters directly; structure II incorporated additional terms for HCT; and the third structure employed as input a non-pulsatile flow estimate equation. Optimal model orders were determined, and the associated models yielded minimum mean flow errors of 5.49% and 0.258 L/min for structure II, and 5.77% and 0.270 L/min for structure III, when validated on unseen data. The models developed in this study present a practical method of accurately estimating iRBP flow in a pulsatile environment.

  5. Quantitating error in blood flow measurements with radioactive microspheres

    Energy Technology Data Exchange (ETDEWEB)

    Austin, R.E. Jr.; Hauck, W.W.; Aldea, G.S.; Flynn, A.E.; Coggins, D.L.; Hoffman, J.I.

    1989-07-01

    Accurate determination of the reproducibility of measurements using the microsphere technique is important in assessing differences in blood flow to different organs or regions within organs, as well as changes in perfusion under various experimental conditions. The sources of error of the technique are briefly reviewed. In addition, we derived a method for combining quantifiable sources of error into a single estimate that was evaluated experimentally by simultaneously injecting eight or nine sets of microspheres (each with a different radionuclide label) into four anesthetized dogs. Each nuclide was used to calculate blood flow in 145-190 myocardial regions. We compared each flow determination (using a single nuclide label) with a weighted mean for the piece (based on the remaining nuclides). The difference was defined as ''measured'' error. In all, there were a total of 5,975 flow observations. We compared measured error with theoretical estimates based on the Poisson error of radioactive disintegration and microsphere entrapment, nuclide separation error, and reference flow error. We found that combined estimates based on these sources completely accounted for measured error in the relative distribution of microspheres. In addition, our estimates of the error in measuring absolute flows (which were established using microsphere reference samples) slightly, but significantly, underestimated measured error in absolute flow.

  6. Noninvasive miniaturized mass-flow meter using a curved cannula for implantable axial flow blood pump.

    Science.gov (United States)

    Kosaka, Ryo; Nishida, Masahiro; Maruyama, Osamu; Yamane, Takashi

    2011-01-01

    Blood flow should be measured to monitor conditions of patients with implantable artificial hearts continuously and noninvasively. We have developed a noninvasive miniaturized mass-flow meter using a curved cannula for an axial flow blood pump. The mass-flow meter utilized centrifugal force generated by the mass-flow rate in the curved cannula. Two strain gauges served as sensors. Based on the numerical analysis, the first gauge, attached to the curved area, measured static pressure and centrifugal force, and the second, attached to the straight area, measured static pressure for static pressure compensation. The mass-flow rate was determined by the differences in output from the two gauges. To compensate for the inertia force under the pulsatile flow, a 0.75-Hz low-pass filter was added to the electrical circuit. In the evaluation tests, numerical analysis and an actual measurement test using bovine blood were performed to evaluate the measurement performances. As a result, in the numerical analysis, the relationship between the differential pressure caused by centrifugal force and the flow rate was verified. In the actual measurement test, measurement error was less than ± 0.5 L/min, and the time delay was 0.12 s. We confirmed that the developed mass-flow meter was able to measure mass-flow rate continuously and noninvasively.

  7. Effect of dopamine on bethanechol-stimulated gastric mucosal blood flow and gastric acid secretion in dogs with gastric fistula

    DEFF Research Database (Denmark)

    Hovendal, C P; Bech, K

    1982-01-01

    by high dopamine doses could be explained by a beta 1 stimulation. Dopamine (10 micrograms/kg/min) was found to increase the bethanechol-stimulated gastric mucosal blood flow. Phentolamine (alpha blackade) increased this dopamine-elevated blood flow further, with a significant increase in the ratio...

  8. [Research on flow characteristics in a non-blade centrifugal blood pump based on CFD technology].

    Science.gov (United States)

    Cheng, Yunzhang; Luo, Binhai; Wu, Wenquan; Jiang, Lei

    2010-10-01

    The problem of thrombus and hemolysis in blood pump has always been an important topic to study in the development of the blood pump. Numbers of research results show that it is the complicated flow and the high shear stress of the mechanical movement that result in the thrombus and hemolysis. In this study, with the cooperation of Shanghai Children's Medical Center, we have used computational fluid dynamics (CFD) commercial software FLUENT to compute and analyze the flow characteristics in a non-blade centrifugal blood pump. The results figure out that this pump has a reasonable flow distribution and the shear stress distribution is under the critical broken state of red blood cell; meanwhile, there is less thrombus and hemolysis in this pump. So it is in the foreground for clinical use.

  9. CHRONOBIOLOGY OF HIGH BLOOD PRESSURE

    Science.gov (United States)

    Cornélissen, G.; Halberg, F.; Bakken, E. E.; Wang, Z.; Tarquini, R.; Perfetto, F.; Laffi, G.; Maggioni, C.; Kumagai, Y.; Homolka, P.; Havelková, A.; Dušek, J.; Svačinová, H.; Siegelová, J.; Fišer, B.

    2008-01-01

    BIOCOS, the project aimed at studying BIOlogical systems in their COSmos, has obtained a great deal of expertise in the fields of blood pressure (BP) and heart rate (HR) monitoring and of marker rhythmometry for the purposes of screening, diagnosis, treatment, and prognosis. Prolonging the monitoring reduces the uncertainty in the estimation of circadian parameters; the current recommendation of BIOCOS requires monitoring for at least 7 days. The BIOCOS approach consists of a parametric and a non-parametric analysis of the data, in which the results from the individual subject are being compared with gender- and age-specified reference values in health. Chronobiological designs can offer important new information regarding the optimization of treatment by timing its administration as a function of circadian and other rhythms. New technological developments are needed to close the loop between the monitoring of blood pressure and the administration of antihypertensive drugs. PMID:19122770

  10. Blood flow in the forearm in patients with Rheumatoid arthritis and healthy subjects under local thermotherapy

    Directory of Open Access Journals (Sweden)

    C. Mucha

    2002-02-01

    Full Text Available Objectives: Muscle blood flow in the forearm of patients with rheuma-toid arthritis and healthy volunteers following treatment with temperature increasingarm baths, mudpacks and short- or decimeter-wave diathermy was studied in thisinvestigation. The aim of the study was to find out the difference of reactive hyperemia between the different temperature methods as well as the influence on theconsensual reaction. Subjects: Eighty patients with rheumatoid arthritis, stage 3 according toSteinbrocker, as well as 80 healthy human subjects had been assigned numerically in the four therapy- and controlgroups. Patients with diseases influencing the peripheral blood flow were excluded. Design: Blood flow was measured by venous occlusion plethysmography in both forearms with the subjects lyingsupine. The application of the local heat therapies had been excluded on the left forearm. The forearm blood flow wasmonitored before heat therapy, directly after as well as in two further 10 minutes intervals. An analysis of variancewas used to determine the influence on blood flow of the response to the heat therapies in patients with rheumatoidarthritis and healthy subjects.Results: Under homogeneous starting conditions and a statistically uniformed high blood flow in rest the reactive values of blood flow on the left-hand side of application and the right consensual side showed high significant differencesbetween all methods of therapy. Differences between the patients and the healthy subjects only showed tendencies withpartially lower reactions, concerning the patients with rheumatoid arthritis. All methods of heat therapy caused a statistically provable consensual reaction that turned out smaller after diathermic methods. Here the post therapeuticreaction of the blood flow on the side of application was also lower or rather shorter. Conclusion: Greater differences of the blood flow in rest between the patients with rheumatoid arthritis and healthysubjects

  11. Effects of midazolam on cerebral blood flow in human volunteers

    Energy Technology Data Exchange (ETDEWEB)

    Forster, A.; Juge, O.; Morel, D.

    1982-06-01

    The effects of intravenously administered midazolam on cerebral blood flow were evaluated in eight healthy volunteers using the /sup 133/Xe inhalation technique. Six minutes after an intravenous dose of 0.15 mg/kg midazolam, the cerebral blood flow decreased significantly (P less than 0.001) from a value of 40.6 +/- 3.3 to a value of 27.0 +/- 5.0 ml . 100 g-1 . min-1. Cerebrovascular resistance (CVR) increased from 2.8 +/- 0.2 to 3.9 to 0.6 mmHg/(ml . 100 g-1 . min-1)(P less than 0.001). Mean arterial blood pressure decreased significantly (P less than 0.05) from 117 +/- 8 to 109 +/- 9 mmHg and arterial carbon dioxide tension increased from 33.9 +/- 2.3 to 38.6 +/- 3.2 mmHg (P less than 0.05). Arterial oxygen tension remained stable throughout the study, 484 +/- 95 mmHg before the administration of midazolam and 453 +/- 76 mmHg after. All the subjects slept after the injection of the drug and had anterograde amnesia of 24.5 +/- 5 min. The decrease in mean arterial blood pressure was probably not important since it remained in the physiologic range for cerebral blood flow autoregulation. The increase in arterial carbon dioxide tension observed after the midazolam injection may have partially counteracted the effect of this new benzodiazepine on cerebral blood flow. Our data suggest that midazolam might be a safe agent to use for the induction of anethesia in neurosurgical patients with intracranial hypertension.

  12. Quantitative blood flow velocity imaging using laser speckle flowmetry

    Science.gov (United States)

    Nadort, Annemarie; Kalkman, Koen; van Leeuwen, Ton G.; Faber, Dirk J.

    2016-04-01

    Laser speckle flowmetry suffers from a debated quantification of the inverse relation between decorrelation time (τc) and blood flow velocity (V), i.e. 1/τc = αV. Using a modified microcirculation imager (integrated sidestream dark field - laser speckle contrast imaging [SDF-LSCI]), we experimentally investigate on the influence of the optical properties of scatterers on α in vitro and in vivo. We found a good agreement to theoretical predictions within certain limits for scatterer size and multiple scattering. We present a practical model-based scaling factor to correct for multiple scattering in microcirculatory vessels. Our results show that SDF-LSCI offers a quantitative measure of flow velocity in addition to vessel morphology, enabling the quantification of the clinically relevant blood flow, velocity and tissue perfusion.

  13. Blood flow in the cerebral venous system: modeling and simulation.

    Science.gov (United States)

    Miraucourt, Olivia; Salmon, Stéphanie; Szopos, Marcela; Thiriet, Marc

    2017-04-01

    The development of a software platform incorporating all aspects, from medical imaging data, through three-dimensional reconstruction and suitable meshing, up to simulation of blood flow in patient-specific geometries, is a crucial challenge in biomedical engineering. In the present study, a fully three-dimensional blood flow simulation is carried out through a complete rigid macrovascular circuit, namely the intracranial venous network, instead of a reduced order simulation and partial vascular network. The biomechanical modeling step is carefully analyzed and leads to the description of the flow governed by the dimensionless Navier-Stokes equations for an incompressible viscous fluid. The equations are then numerically solved with a free finite element software using five meshes of a realistic geometry obtained from medical images to prove the feasibility of the pipeline. Some features of the intracranial venous circuit in the supine position such as asymmetric behavior in merging regions are discussed.

  14. Simulation of red blood cell aggregation in shear flow.

    Science.gov (United States)

    Lim, B; Bascom, P A; Cobbold, R S

    1997-01-01

    A simulation model has been developed for red blood cell (RBC) aggregation in shear flow. It is based on a description of the collision rates of RBC, the probability of particles sticking together, and the breakage of aggregates by shear forces. The influence of shear rate, hematocrit, aggregate fractal dimension, and binding strength on aggregation kinetics were investigated and compared to other theoretical and experimental results. The model was used to simulate blood flow in a long large diameter tube under steady flow conditions at low Reynolds numbers. The time and spatial distribution of the state of aggregation are shown to be in qualitative agreement with previous B-mode ultrasound studies in which a central region of low echogenicity was noted. It is suggested that the model can provide a basis for interpreting prior measurements of ultrasound echogenicity and may help relate them to the local state of aggregation.

  15. Quantitative blood flow measurements in the small animal cardiopulmonary system using digital subtraction angiography

    Energy Technology Data Exchange (ETDEWEB)

    Lin Mingde; Marshall, Craig T.; Qi, Yi; Johnston, Samuel M.; Badea, Cristian T.; Piantadosi, Claude A.; Johnson, G. Allan [Department of Radiology, Center for In Vivo Microscopy and Department of Biomedical Engineering, Duke University Medical Center, Box 3302, Durham, North Carolina 27710 (United States); Division of Pulmonary and Critical Care Medicine and Center for Hyperbaric Medicine and Environmental Physiology, Duke University Medical Center, Box 3823, Durham, North Carolina 27710 (United States); Department of Radiology, Center for In Vivo Microscopy, Duke University Medical Center, Box 3302, Durham, North Carolina 27710 (United States); Department of Radiology, Center for In Vivo Microscopy and Department of Biomedical Engineering, Duke University Medical Center, Box 3302, Durham, North Carolina 27710 (United States); Department of Radiology, Center for In Vivo Microscopy, Duke University Medical Center, Box 3302, Durham, North Carolina 27710 (United States); Division of Pulmonary and Critical Care Medicine and Center for Hyperbaric Medicine and Environmental Physiology, Duke University Medical Center, Box 3823, Durham, North Carolina 27710 (United States); Department of Radiology, Center for In Vivo Microscopy and Department of Biomedical Engineering, Duke University Medical Center, Box 3302, Durham, North Carolina 27710 (United States)

    2009-11-15

    Purpose: The use of preclinical rodent models of disease continues to grow because these models help elucidate pathogenic mechanisms and provide robust test beds for drug development. Among the major anatomic and physiologic indicators of disease progression and genetic or drug modification of responses are measurements of blood vessel caliber and flow. Moreover, cardiopulmonary blood flow is a critical indicator of gas exchange. Current methods of measuring cardiopulmonary blood flow suffer from some or all of the following limitations--they produce relative values, are limited to global measurements, do not provide vasculature visualization, are not able to measure acute changes, are invasive, or require euthanasia. Methods: In this study, high-spatial and high-temporal resolution x-ray digital subtraction angiography (DSA) was used to obtain vasculature visualization, quantitative blood flow in absolute metrics (ml/min instead of arbitrary units or velocity), and relative blood volume dynamics from discrete regions of interest on a pixel-by-pixel basis (100x100 {mu}m{sup 2}). Results: A series of calibrations linked the DSA flow measurements to standard physiological measurement using thermodilution and Fick's method for cardiac output (CO), which in eight anesthetized Fischer-344 rats was found to be 37.0{+-}5.1 ml/min. Phantom experiments were conducted to calibrate the radiographic density to vessel thickness, allowing a link of DSA cardiac output measurements to cardiopulmonary blood flow measurements in discrete regions of interest. The scaling factor linking relative DSA cardiac output measurements to the Fick's absolute measurements was found to be 18.90xCO{sub DSA}=CO{sub Fick}. Conclusions: This calibrated DSA approach allows repeated simultaneous visualization of vasculature and measurement of blood flow dynamics on a regional level in the living rat.

  16. Cerebral blood flow in migraine and cortical spreading depression

    Energy Technology Data Exchange (ETDEWEB)

    Lauritzen, M.

    1987-01-01

    In a series of migraine patients, carotid arteriography was carried out as part of the clinical evalution. Nine patients developed a migrainous attack with focal neurological symptoms and headache after the angiography and during the subsequent, ongoing regional cerebral blood flow rCBF study. rCBF was measured by bolus injection of Xenon/sup 133/ into the internal carotid artery and a gamma camera with 254 collimated scintillation detectors covering the lateral aspect of the hemisphere. This technique depicts rCBF mainly at the level of the superficial cortex, with no depth resolution. The resolution is 1 cm/sup 2/ providing detailed spatial information of the cortical blood flow. Other methods for measuring local blood flow in animal and man employ a radioactive, freely diffusible tracer, in combination with an autoradiographic technique for the assessment of the tissue concentration, the so-called autoradiographic methods. In the series of patients with spontaneous migraine, rCBF was estimated using an in-vivo application of the autoradiographic principle. Xenon/sup 133/ was administered by inhalation and the time course of the arterial concentration curve was assessed by a scintillation detector over the upper right lung, since the arterial curve has been found to follow the shape of the lung curve. The rCBF was studied accompanying cortical spreading depression in rat experiments to evaluate wheter this phenomenon could explain the blood flow changes in migraine. (/sup 14/C) iodoantipyrine was given as an intravenous bolus injection and the brain content of indicator was determined by tissue sample or autoradiography after 10 or 20 seconds of isotope circulation. The conditions of the autoradiographic methods are that the flow remains constant within the period of measuring, and that the region under study is homogenous with regard to flow and lambda. (EG).

  17. Relationship between blood pressure and cerebral blood flow during supine cycling: influence of aging

    Science.gov (United States)

    Hoffman, Keegan; Tzeng, Yu-Chieh; Hansen, Alex; Ainslie, Philip N.

    2015-01-01

    The cerebral pressure-flow relationship can be quantified as a high-pass filter, where slow oscillations are buffered (exercise, previous studies have reported paradoxical transfer function analysis (TFA) findings (altered phase or intact gain). This study aimed to determine whether these previous findings accurately represent this relationship. Both younger (20–30 yr; n = 10) and older (62–72 yr; n = 9) adults were examined. To enhance the signal-to-noise ratio, large oscillations in blood pressure (via oscillatory lower body negative pressure; OLBNP) were induced during steady-state moderate intensity supine exercise (∼45–50% of heart rate reserve). Beat-to-beat blood pressure, cerebral blood velocity, and end-tidal Pco2 were monitored. Very low frequency (0.02–0.07 Hz) and low frequency (0.07–0.20 Hz) range spontaneous data were quantified. Driven OLBNP point estimates were sampled at 0.05 and 0.10 Hz. The OLBNP maneuvers augmented coherence to >0.97 at 0.05 Hz and >0.98 at 0.10 Hz in both age groups. The OLBNP protocol conclusively revealed the cerebrovascular system functions as a high-pass filter during exercise throughout aging. It was also discovered that the older adults had elevations (+71%) in normalized gain (+0.46 ± 0.36%/%: 0.05 Hz) and reductions (−34%) in phase (−0.24 ± 0.22 radian: 0.10 Hz). There were also age-related phase differences between resting and exercise conditions. It is speculated that these age-related changes in the TFA metrics are mediated by alterations in vasoactive factors, sympathetic tone, or the mechanical buffering of the compliance vessels. PMID:26586907

  18. Quantitative imaging of coronary blood flow

    Directory of Open Access Journals (Sweden)

    Adam M. Alessio

    2010-04-01

    Full Text Available Adam M. Alessio received his PhD in Electrical Engineering from the University of Notre Dame in 2003. During his graduate studies he developed tomographic reconstruction methods for correlated data and helped construct a high-resolution PET system. He is currently a Research Assistant Professor in Radiology at the University of Washington. His research interests focus on improved data processing and reconstruction algorithms for PET/CT systems with an emphasis on quantitative imaging. Erik Butterworth recieved the BA degree in Mathematics from the University of Chicago in 1977. Between 1977 and 1987 he worked as a computer programmer/analyst for several small commercial software firms. Since 1988, he has worked as a software engineer on various research projects at the University of Washington. Between 1988 and 1993 he developed a real-time data aquisition for the analysis of estuarine sediment transport in the department of Geophysics. Between 1988 and 2002 he developed I4, a system for the display and analysis of cardic PET images in the department of Cardiology. Since 1993 he has worked on physiological simulation systems (XSIM from 1993 to 1999, JSim since 1999 at the National Simulation Resource Facility in Cirulatory Mass Transport and Exchange, in the Department of Bioengineering. His research interests include simulation systems and medical imaging. James H. Caldwell, MD, University of Missouri-Columbia 1970, is Professor of Medicine (Cardiology and Radiology and Adjunct Professor of Bioengineering at the University of Washington School of Medicine and Acting Head, Division of Cardiology and Director of Nuclear Cardiology for the University of Washington Hospitals, Seattle WA, USA. James B. Bassingthwaighte, MD, Toronto 1955, PhD Mayo Grad Sch Med 1964, was Professor of Physiology and of Medicine at Mayo Clinic until 1975 when he moved to the University of Washington to chair Bioengineering. He is Professor of Bioengineering and

  19. Blood flow dynamics after laser therapy of port wine stain birthmarks

    Science.gov (United States)

    Huang, Yu-Chih; Tran, Nadia; Ross, E. Victor; Shumaker, Peter R.; Nelson, J. Stuart; Kelly, Kristen; Choi, Bernard

    2009-02-01

    During laser therapy of port wine stain (PWS) birthmarks, regions of persistent perfusion may exist. We hypothesize that such regions, which are not readily visible, exist even during laser surgery performed by highly experienced clinicians. The objective of this study was to use objective feedback to assess the acute vascular response to laser therapy. We have developed a clinic-friendly laser speckle imaging (LSI) instrument to provide the clinician with real-time images of blood flow during laser therapy. We acquired images from patients undergoing laser therapy of PWS birthmarks at Scripps Clinic and Beckman Laser Institute and Medical Clinic. We extracted blood flow maps from the acquired imaging data. Collectively, we have observed two regimes of patient response to therapy: 1) an immediate increase in perfusion within minutes after laser therapy; and 2) an overall decrease in blood perfusion approximately one hour after laser therapy, with distinct regions of persistent perfusion apparent in the majority of post-treatment blood-flow images. A comparison of blood flow in PWS and adjacent normal skin demonstrated that PWS blood flow can be greater than or sometimes equivalent to that of normal skin. Regions of persistent perfusion frequently exist immediately after laser therapy of PWS birthmarks. Existence of these regions may be correlated to the need for multiple treatment sessions to improve substantially PWS skin appearance. With the use of intraoperative LSI, immediate retreatment of these regions may improve the outcome of each session.

  20. MR assessment of absolute myocardial blood flow and vasodilator flow reserve in patients with hypertrophic cardiomyopathy

    Energy Technology Data Exchange (ETDEWEB)

    Kawada, Nanaka; Sakuma, Hajime; Takeda, Kan; Nakagawa, Tsuyoshi; Yamakado, Tetsu; Nakano, Takeshi [Mie Univ., Tsu (Japan). School of Medicine

    1997-04-01

    Absolute coronary blood flow per myocardial mass and coronary flow reserve for the entire left ventricle were evaluated in normals and in patients with hypertrophic cardiomyopathy (HCM) by using fast cine MR imaging and fast velocity encoded cine (VENC) MR imaging. Nine healthy volunteers and 8 patients with HCM were studied with a 1.5 T imager. Breath-hold cine MR images encompassing the whole left ventricle were acquired on short axis imaging planes in order to evaluate myocardial mass. A fast VENC MR images were obtained to measure blood flow volume in the coronary sinus before and after dipyridamole administration (TR/TE=15/5 ms, FOV=28 x 22 cm, slice thickness=5 mm). Coronary flow reserve was calculated as a ratio of hyperemic to baseline coronary flow volumes. In the baseline state, coronary blood flow per myocardial mass was significantly lower in patients with HCM than in normal myocardium (0.56{+-}0.23 vs. 0.78{+-}0.27 ml/min/g, p<0.05). After dipyridamole administration, coronary blood flow per myocardial mass in patients with HCM increased substantially less than that in healthy subjects (0.99{+-}0.38 vs. 2.22{+-}0.55 ml/min/g, p<0.01), resulting in the significantly decreased coronary flow reserve ratio in HCM in comparison with that in normal myocardium (1.86{+-}0.56 vs. 3.11{+-}1.37, p<0.05). In conclusion, breath-hold velocity encoded cine MR imaging is a noninvasive technique which can provide assessments of altered coronary blood flow volume per myocardial mass and vasodilator flow reserve in patients with HCM. (author)

  1. Assessment of maternal cerebral blood flow in patients with preeclampsia

    Directory of Open Access Journals (Sweden)

    Mandić Vesna

    2005-01-01

    Full Text Available Introduction Systemic vasoconstrktion in preeclamptic patients increases vascular resistance, and is manifested by increased arterial blood flow velocity. The aim of the study is to evaluate if there is a change of Doppler indices in maternal medial cerbral artery (MCA in severe preeclampsia due to: 1 severity of clinical symptoms, 2 the beginning of eclamptic attack and 3 the application of anticonvidsive therapy. Material and methods A prospective clinical study included 92 pregnant women, gestational age 28-36 weeks. They were divided into three groups: normotensive (n=30, mild preeclampsia (n=33, and severe preeclampsia (n=29. We investigated maternal cerebral circulation by assessing the MCA. We registrated: pulsatility index (Pi, resistance index (Ri, Systolic/diastolic ratio (S/D, and the maximum systolic, end diastolic and medium velocity. Patients with severe preeclampsia were divided into two subgroups: subgroup 1 included patients without symptoms of threatening eclampsia (n=18; 62.06%; while subgroup 2 included those with symptoms of preeclampsia (n=11; 37.94%. All patients with severe preeclampsia were treated with magnesium sulfate (MgSO4, and cerebral blood flow was measured before and after the treatment. Statistical analysis was done by oneway ANOVA, Student t-test and t-paired sample test. The difference was considered to be significant if p < 0.05. Results Significantly increased Pi, Ri and all velocities were established in the group of patients with severe preeclampsia compared with the other two groups. In the group with severe preeclamsia we registrated significantly increased values of all velocities (patients with signs of threatening eclampsia. After MgSO4 treatment in patients with severe preeclampsia significantly decreased values of Pi, Ri, S/D ratio and all velocities were registered. Discussion In the studied group of patients with severe preclampsia we found increased velocity values, Pi and Ri, especially in

  2. A Reconstruction Method of Blood Flow Velocity in Left Ventricle Using Color Flow Ultrasound

    Directory of Open Access Journals (Sweden)

    Jaeseong Jang

    2015-01-01

    Full Text Available Vortex flow imaging is a relatively new medical imaging method for the dynamic visualization of intracardiac blood flow, a potentially useful index of cardiac dysfunction. A reconstruction method is proposed here to quantify the distribution of blood flow velocity fields inside the left ventricle from color flow images compiled from ultrasound measurements. In this paper, a 2D incompressible Navier-Stokes equation with a mass source term is proposed to utilize the measurable color flow ultrasound data in a plane along with the moving boundary condition. The proposed model reflects out-of-plane blood flows on the imaging plane through the mass source term. The boundary conditions to solve the system of equations are derived from the dimensions of the ventricle extracted from 2D echocardiography data. The performance of the proposed method is evaluated numerically using synthetic flow data acquired from simulating left ventricle flows. The numerical simulations show the feasibility and potential usefulness of the proposed method of reconstructing the intracardiac flow fields. Of particular note is the finding that the mass source term in the proposed model improves the reconstruction performance.

  3. Skeletal blood flow, iliac histomorphometry, and strontium kinetics in osteoporosis: a relationship between blood flow and corrected apposition rate

    Energy Technology Data Exchange (ETDEWEB)

    Reeve, J.; Arlot, M.; Wootton, R.; Edouard, C.; Tellez, M.; Hesp, R.; Green, J.R.; Meunier, P.J.

    1988-06-01

    In 20 untreated patients with idiopathic or postmenopausal osteoporosis, kinetic studies of skeletal blood flow (using /sup 18/F) and bone turnover (using /sup 85/Sr) were combined with dynamic histomorphometry performed on transiliac biopsies taken within 6 weeks of each other. In 8 patients the combined studies were repeated after treatment. A further 5 patients were studied only while receiving treatment. As expected, skeletal blood flow measured by /sup 18/F correlated with an index of /sup 85/Sr uptake into the exchangeable pools of bone. Additionally and independently, skeletal blood flow correlated with an index of the work rate of the osteoblasts in each multicellular unit of bone (the corrected apposition rate of Parfitt). These correlations were statistically significant in both the untreated patients (P less than 0.05) and the whole group (P less than 0.001). Further indices related to bone turnover at the level of the skeleton as a whole were significantly associated with skeletal blood flow only in the combined group.

  4. Ozone Therapy on Cerebral Blood Flow: A Preliminary Report

    Directory of Open Access Journals (Sweden)

    Bernardino Clavo

    2004-01-01

    Full Text Available Ozone therapy is currently being used in the treatment of ischemic disorders, but the underlying mechanisms that result in successful treatment are not well known. This study assesses the effect of ozone therapy on the blood flow in the middle cerebral and common carotid arteries. Seven subjects were recruited for the therapy that was performed by transfusing ozone-enriched autologous blood on 3 alternate days over 1 week. Blood flow quantification in the common carotid artery (n = 14 was performed using color Doppler. Systolic and diastolic velocities in the middle cerebral artery (n = 14 were estimated using transcranial Doppler. Ultrasound assessments were conducted at the following three time points: 1 basal (before ozone therapy, 2 after session #3 and 3 1 week after session #3. The common carotid blood flow had increased by 75% in relation to the baseline after session #3 (P < 0.001 and by 29% 1 week later (P = 0.039. In the middle cerebral artery, the systolic velocity had increased by 22% after session #3 (P = 0.001 and by 15% 1 week later (P = 0.035, whereas the diastolic velocity had increased by 33% after session #3 (P < 0.001 and by 18% 1 week later (P = 0.023. This preliminary Doppler study supports the clinical experience of achieving improvement by using ozone therapy in peripheral ischemic syndromes. Its potential use as a complementary treatment in cerebral low perfusion syndromes merits further clinical evaluation.

  5. Structural analysis of red blood cell aggregates under shear flow.

    Science.gov (United States)

    Chesnutt, J K W; Marshall, J S

    2010-03-01

    A set of measures of red blood cell (RBC) aggregates are developed and applied to examine the aggregate structure under plane shear and channel flows. Some of these measures are based on averages over the set of red blood cells which are in contact with each other at a given time. Other measures are developed by first fitting an ellipse to the planar projection of the aggregate, and then examining the area and aspect ratio of the fit ellipse as well as the orientations of constituent RBCs with respect to the fit ellipse axes. The aggregate structural measures are illustrated using a new mesoscale computational model for blood cell transport, collision and adhesion. The sensitivity of this model to change in adhesive surface energy density and shear rate on the aggregate structure is examined. It is found that the mesoscale model predictions exhibit reasonable agreement with experimental and theoretical data for blood flow in plane shear and channel flows. The new structural measures are used to examine the differences between predictions of two- and three-dimensional computations of the aggregate formation, showing that two-dimensional computations retain some of the important aspects of three-dimensional computations.

  6. THE PECULIARITIES OF CEREBRAL BLOOD FLOW IN PATIENTS WITH CHRONIC HEPATITIS

    Directory of Open Access Journals (Sweden)

    V. E. Kulikov

    2015-12-01

    Full Text Available Aim. To study extra- and intracranial hemodynamics in patients with chronic hepatitis of different activity.Material and methods. Ultrasonography of the cerebral blood flow was performed in 576 patients with chronic hepatitis.Results. Contralateral hemyspherical asymmetry (more than 30 % of the maximum linear rate of blood flow in the medium cerebral arteries and decrease in resistance index (0,55±0,09 and pulsativity index (1,34±0,66 were found in 33,8 % of patients with chronic hepatitis of high activity. Collateral blood flow reduction through connecting arteries of Willis circle was revealed in 13,8 % of patients. The tortuosity of arteries and thickening of intima-media complex was found in patients with chronic hepatitis (mainly of high activity. It leads to decline of cerebral blood flow.Conclusion. Symptomatic and asymptomatic cerebral blood flow disturbances were observed in 23,2% and 38,8% of patients with active chronic hepatitis respectively.

  7. THE PECULIARITIES OF CEREBRAL BLOOD FLOW IN PATIENTS WITH CHRONIC HEPATITIS

    Directory of Open Access Journals (Sweden)

    V. E. Kulikov

    2007-01-01

    Full Text Available Aim. To study extra- and intracranial hemodynamics in patients with chronic hepatitis of different activity.Material and methods. Ultrasonography of the cerebral blood flow was performed in 576 patients with chronic hepatitis.Results. Contralateral hemyspherical asymmetry (more than 30 % of the maximum linear rate of blood flow in the medium cerebral arteries and decrease in resistance index (0,55±0,09 and pulsativity index (1,34±0,66 were found in 33,8 % of patients with chronic hepatitis of high activity. Collateral blood flow reduction through connecting arteries of Willis circle was revealed in 13,8 % of patients. The tortuosity of arteries and thickening of intima-media complex was found in patients with chronic hepatitis (mainly of high activity. It leads to decline of cerebral blood flow.Conclusion. Symptomatic and asymptomatic cerebral blood flow disturbances were observed in 23,2% and 38,8% of patients with active chronic hepatitis respectively.

  8. Intrapericardial denervation - Radial artery blood flow and heart rate responses to LBNP

    Science.gov (United States)

    Mckeever, Kenneth H.; Skidmore, Michael G.; Keil, Lanny C.; Sandler, Harold

    1990-01-01

    The effects of intrapericardial denervation on the radial artery blood flow velocity (RABFV) and heart rate (HR) responses to LBNP in rhesus monkeys were investigated by measuring the RABFV transcutaneously by a continuous-wave Doppler ultrasonic flowmeter in order to derive an index of forearm blood flow response to low (0 to -20 mm Hg) and high (0 to -60 mm Hg) ramp exposures during supine LBNP. Four of the eight subjects were subjected to efferent and afferent cardiac denervation. It was found that, during low levels of LBNP, monkeys with cardiac denervation exhibited no cardiopulmonary baroreceptor-mediated change in the RABFV or HR, unlike the intact animals, which showed steady decreases in RABFV during both high- and low-pressure protocols. It is suggested that forearm blood flow and HR responses to low-level LBNP, along with pharmacological challenge, are viable physiological tests for verifying the completeness of atrial and cardiopulmonary baroreceptor denervation.

  9. Narcolepsy: regional cerebral blood flow during sleep and wakefulness

    Energy Technology Data Exchange (ETDEWEB)

    Sakai, F.; Meyer, J.S.; Karacan, I.; Yamaguchi, F.; Yamamoto, M.

    1979-01-01

    Serial measurements of regional cerebral blood flow were made by the 135Xe inhalation method during the early stages of sleep and wakefulness in eight normal volunteers and 12 patients with narcolepsy. Electroencephalogram, electro-oculogram, and submental electromyogram were recorded simultaneously. In normals, mean hemispheric gray matter blood flow (Fg) during stages I and II sleep was significantly less than waking values. Maximum regional blood flow decreases during sleep occurred in the brainstem-cerebellar, right inferior temporal, and bilateral frontal regions. In patients with narcolepsy, mean hemispheric Fg while awake was 80.5 +- 13 ml per 100 gm brain per minute. During REM sleep, mean hemispheric Fg increased concurrently with large increases in brainstem-cerebellar region flow. During stages I and II sleep without REM, there were significant increases in mean hemispheric Fg and brainstem-cerebellar Fg, just the opposite of changes in normals. In narcolepsy, there appears to be a reversal of normal cerebral deactivation patterns, particularly involving the brainstem, during stages I and II sleep.

  10. Axial dispersion in flowing red blood cell suspensions

    Science.gov (United States)

    Podgorski, Thomas; Losserand, Sylvain; Coupier, Gwennou

    2016-11-01

    A key parameter in blood microcirculation is the transit time of red blood cells (RBCs) through an organ, which can influence the efficiency of gas exchange and oxygen availability. A large dispersion of this transit time is observed in vivo and is partly due to the axial dispersion in the flowing suspension. In the classic Taylor-Aris example of a solute flowing in a tube, the combination of molecular diffusion and parabolic velocity profile leads to enhanced axial dispersion. In suspensions of non-Brownian deformable bodies such as RBCs, axial dispersion is governed by a combination of shear induced migration and shear-induced diffusion arising from hydrodynamic interactions. We revisit this problem in the case of RBC pulses flowing in a microchannel and show that the axial dispersion of the pulse eventually saturates with a final extension that depends directly on RBC mechanical properties. The result is especially interesting in the dilute limit since the final pulse length depends only on the channel width, exponent of the migration law and dimensionless migration velocity. In continuous flow, the dispersion of transit times is the result of complex cell-cell and cell-wall interactions and is strongy influenced by the polydispersity of the blood sample. The authors acknowledge support from LabEx TEC21 and CNES.

  11. Methods for blood flow measurements using ultrasound contrast agents

    Science.gov (United States)

    Fowlkes, J. Brian

    2003-10-01

    Blood flow measurements using ultrasound contrast agents are being investigated for myocardial perfusion and more recently in other organ systems. The methods are based largely on the relative increase in echogenicity due to the concentration of bubbles present in the ultrasound beam. In the simplest form, regional differences in blood volume can be inferred but the possibility exists to extract perfusion from the transit of contrast agent through tissue. Perfusion measurements rely on determining the flux of blood through a tissue volume and as such require knowledge of the fractional blood volume (FBV), i.e., ml blood/g tissue and the rate of exchange, commonly measured as the mean transit time (MTT). This presentation will discuss methods of determining each of these values and their combination to estimate tissue perfusion. Underlying principles of indicator-dilution theory will be provided in the context of ultrasound contrast agents. Current methods for determining MTT will include imaging of the intravenous bolus, in-plane contrast disruption with interval and real-time contrast recovery imaging, and control of contrast agent flow using arterial disruption (contrast interruption). The advantages and limitations of the methods will be examined along with current applications. [Work supported in part by NIH.

  12. In vivo photoacoustic imaging of transverse blood flow using Doppler broadening of bandwidth

    OpenAIRE

    Yao, Junjie; Maslov, Konstantin I.; Shi, Yunfei; Taber, Larry A.; Lihong V. Wang

    2010-01-01

    A new method is proposed to measure transverse blood flow using photoacoustic Doppler broadening of bandwidth. By measuring bovine blood flowing through a plastic tube, the linear dependence of the broadening on the flow speed was validated. The blood flow of the microvasculature in a mouse ear and a chicken embryo (stage 16) was also studied.

  13. In vivo photoacoustic imaging of transverse blood flow by using Doppler broadening of bandwidth

    OpenAIRE

    Yao, Junjie; Maslov, Konstantin I.; Shi, Yunfei; Taber, Larry A.; Lihong V. Wang

    2010-01-01

    A method is proposed to measure transverse blood flow by using photoacoustic Doppler broadening of bandwidth. By measuring bovine blood flowing through a plastic tube, the linear dependence of the broadening on the flow speed was validated. The blood flow of the microvasculature in a mouse ear and a chicken embryo (stage 16) was also studied.

  14. Lattice Boltzmann Simulation of Blood Flow in Blood Vessels with the Rolling Massage

    Institute of Scientific and Technical Information of China (English)

    YI Hou-Hui; XU Shi-Xiong; QIAN Yue-Hong; FANG Hai-Ping

    2005-01-01

    @@ The rolling massage manipulation is a classic Chinese massage, which is expected to improve the circulation by pushing, pulling and kneading of the muscle. A model for the rolling massage manipulation is proposed and the lattice Boltzmann method is applied to study the blood flow in the blood vessels. The simulation results show that the blood flux is considerably modified by the rolling massage and the explicit value depends on the rolling frequency, the rolling depth, and the diameter of the vessel. The smaller the diameter of the blood vessel, the larger the enhancement of the blood flux by the rolling massage. The model, together with the simulation results,is expected to be helpful to understand the mechanism and further development of rolling massage techniques.

  15. Anisodamine augments mucosal blood flow during gut ischemia/reperfusion

    Institute of Scientific and Technical Information of China (English)

    Hu Sen; Sheng Zhiyong

    2002-01-01

    Objective: To determine if anisodamine is able to augment mucosal perfusion during gut ischemia-reperfusion (I/R). Methods: A jejunal sac was formed in Sprague Dawley rat. A Laser Doppler probe and a tonometer were inserted into the sac which was filled with saline. The superior mesenteric artery was occluded (SMAO) for 60minutes followed by 90 minutes of reperfusion. At the end of 60 minutes of SMAO, either 0.2mg/kg of anisodmine or dobutamine was injected into the jejunal sac. Laser Doppler mucosal blood flow and regional PCO2 (PrCO2) measurements were made. Results: Mucosal blood flow was significantly increased at 30,60 and 90 minutes of reperfusion (R30, R60, R90 ) when intraluminal anisodamine or dobutamine was introduced compared to intraluminal saline only (44±3.3)% or (48±4.1)% vs. (37±2.6) % at R30, (57±5.0)% or (56±4.7)% vs. (45±2.7)% at R60, (64±3.3) % or (56 ± 4.2) % vs. (48 ± 3.4) % at R90 , respectively P<0.05). Blood flow changes were also reflected by lowering of jejunal PrCO2 measurements after intraluminal anisodamine or dobutamine compared with that of the saline controls (41±3. 1)mmHg or (44±3.0)mmHg vs. (49±3.7) mmHg at R30 , (38±3.7)mmHg or (40±2. 1)mmHg vs. (47±3.8) mmHgat R60, (34±2.1) mmHg or (39± 3.0) mmHg vs. (46±3.4) mmHg at R90, respectively,P<0. 05). The most interesting finding was that there were significantly higher mucosal blood flow and lower jejunal PrCO2 in anisodamine group than those in dobutamine group at 90 minutes of reperfusion (64± 3.3) %vs. (56±4.2)% for blood flow or (34 ± 2.1)mmHg vs. (39 ± 3.0)mmHg for PrCO2, respectively, P<0.05),suggesting that anisodamine had more lasting effect on mucosal perfusion than dobutamine. Conclusions:Intraluminal anisodamine can augment mucosal blood flow during gut I/R, and it may provide the protective effect on gut from ischemia and reperfusion injury.

  16. Effect of pregnancy on regional cerebral blood flow

    Energy Technology Data Exchange (ETDEWEB)

    Nagamachi, Shigeki; Hoshi, Hiroaki; Jinnouchi, Seishi; Ohnishi, Takashi; Futami, Shigemi; Watanabe, Katsushi; Ikeda, Tomoaki; Mori, Norimasa [Miyazaki Medical Coll., Kiyotake (Japan)

    1993-12-01

    Regional cerebral blood flow (r-CBF) of 10 pregnant women were quantified by {sup 133}Xe SPECT study with inhalation method before and after artificial abortion. During pregnancy, value of r-CBF in each region except occipital lobe was significantly higher than that of the post abortion. Arterial blood gas was analyzed after SPECT procedure. P{sub co2} concentration increased significantly after artificial abortion. Although its mechanism is unknown, our preliminary work demonstrates that r-CBF increased by pregnancy. (author).

  17. Sympathetic reflex control of blood flow in human peripheral tissues

    DEFF Research Database (Denmark)

    Henriksen, O

    1991-01-01

    Sympathetic vasoconstrictor reflexes are essential for the maintenance of arterial blood pressure in upright position. It has been generally believed that supraspinal sympathetic vasoconstrictor reflexes elicited by changes in baroreceptor activity play an important role. Recent studies on human...... sympathetic vasoconstrictor reflexes are blocked. Blood flow has been measure by the local 133Xe-technique. The results indicate the presence of spinal as well as supraspinal sympathetic vasoconstrictor reflexes to human peripheral tissues. Especially is emphasized the presence of a local sympathetic veno...

  18. Holographic laser Doppler imaging of pulsatile blood flow

    CERN Document Server

    Bencteux, Jeffrey; Kostas, Thomas; Bayat, Sam; Atlan, Michael

    2015-01-01

    We report on wide-field imaging of pulsatile motion induced by blood flow using heterodyne holographic interferometry on the thumb of a healthy volunteer, in real-time. Optical Doppler images were measured with green laser light by a frequency-shifted Mach-Zehnder interferometer in off-axis configuration. The recorded optical signal was linked to local instantaneous out-of-plane motion of the skin at velocities of a few hundreds of microns per second, and compared to blood pulse monitored by plethysmoraphy during an occlusion-reperfusion experiment.

  19. Tomographic cerebral blood flow measurement during carotid surgery

    DEFF Research Database (Denmark)

    Rathenborg, Lisbet Knudsen; Vorstrup, Sidsel; Olsen, K S

    1994-01-01

    OBJECTIVES: The aim of the study was to depict regional cerebral blood flow (rCBF) during carotid cross clamping using 99mTechnetium-hexamethylpropylene amine oxime (TcHMPAO). This tracer rapidly passes the blood-brain barrier and is retained for hours in the brain tissue. Injecting TcHMPAO during...... RESULTS: We found a significant correlation between stump pressure and enhancement of side-to-side asymmetry in rCBF due to carotid cross clamping. Pronounced variations were seen in which regions were deprived of perfusion during clamping. CONCLUSION: TcHMPAO allows tomographic assessment of CBF during...

  20. Resistance exercise with different volumes: blood pressure response and forearm blood flow in the hypertensive elderly

    Science.gov (United States)

    Brito, Aline de Freitas; de Oliveira, Caio Victor Coutinho; Brasileiro-Santos, Maria do Socorro; Santos, Amilton da Cruz

    2014-01-01

    Background The purpose of this study was to evaluate the effect of two sessions of resistance exercise with different volumes on post-exercise hypotension, forearm blood flow, and forearm vascular resistance in hypertensive elderly subjects. Methods The study was conducted with ten hypertensive elderly (65±3 years, 28.7±3 kg/m2) subjected to three experimental sessions, ie, a control session, exercise with a set (S1), and exercise with three sets (S3). For each session, the subjects were evaluated before and after intervention. In the pre-intervention period, blood pressure, forearm blood flow, and forearm vascular resistance were measured after 10 minutes of rest in the supine position. Thereafter, the subjects were taken to the gym to perform their exercise sessions or remained at rest during the same time period. Both S1 and S3 comprised a set of ten repetitions of ten exercises, with an interval of 90 seconds between exercises. Subsequently, the measurements were again performed at 10, 30, 50, 70, and 90 minutes of recovery (post-intervention) in the supine position. Results Post-exercise hypotension was greater in S3 than in S1 (systolic blood pressure, −26.5±4.2 mmHg versus −17.9±4.7 mmHg; diastolic blood pressure, −13.8±4.9 mmHg versus −7.7±5 mmHg, P<0.05). Similarly, forearm blood flow and forearm vascular resistance changed significantly in both sessions with an increase and decrease, respectively, that was more evident in S3 than in S1 (P<0.05). Conclusion Resistance exercises with higher volume were more effective in causing post-exercise hypotension, being accompanied by an increase in forearm blood flow and a reduction of forearm vascular resistance. PMID:25540580

  1. Involvement of calcitonin gene-related peptide in migraine: regional cerebral blood flow and blood flow velocity in migraine patients

    DEFF Research Database (Denmark)

    Lassen, L.H.; Jacobsen, V.B.; Haderslev, P.A.

    2008-01-01

    g/min) or placebo for 20 min was studied in 12 patients with migraine without aura outside attacks. Xenon-133 inhalation SPECT-determined regional cerebral blood flow (rCBF) and transcranial Doppler (TCD)-determined blood velocity (V-mean) in the middle cerebral artery (MCA), as well as the heart......Calcitonin gene-related peptide (CGRP)-containing nerves are closely associated with cranial blood vessels. CGRP is the most potent vasodilator known in isolated cerebral blood vessels. CGRP can induce migraine attacks, and two selective CGRP receptor antagonists are effective in the treatment...... of migraine attacks. It is therefore important to investigate its mechanism of action in patients with migraine. We here investigate the effects of intravenous human alpha-CGRP (h alpha CGRP) on intracranial hemodynamics. In a double-blind, cross-over study, the effect of intravenous infusion of haCGRP (2 mu...

  2. Effect of TIPS placement on portal and splanchnic arterial blood flow in 4-dimensional flow MRI

    Energy Technology Data Exchange (ETDEWEB)

    Stankovic, Zoran [Northwestern University, Department of Radiology, Feinberg School of Medicine, Chicago, IL (United States); University Medical Center Freiburg, Department of Diagnostic Radiology and Medical Physics, Freiburg (Germany); Roessle, Martin; Schultheiss, Michael [University Medical Center Freiburg, Department of Gastroenterology, Freiburg (Germany); Euringer, Wulf; Langer, Mathias [University Medical Center Freiburg, Department of Diagnostic Radiology and Medical Physics, Freiburg (Germany); Salem, Riad; Barker, Alex; Carr, James; Collins, Jeremy D. [Northwestern University, Department of Radiology, Feinberg School of Medicine, Chicago, IL (United States); Markl, Michael [Northwestern University, Department of Radiology, Feinberg School of Medicine, Chicago, IL (United States); Northwestern University, Department of Biomedical Engineering, McCormick School of Engineering, Chicago, IL (United States)

    2015-09-15

    To assess changes in portal and splanchnic arterial haemodynamics in patients undergoing transjugular intrahepatic portosystemic shunt (TIPS) using four-dimensional (4D) flow MRI, a non-invasive, non-contrast imaging technique. Eleven patients undergoing TIPS implantation were enrolled. K-t GRAPPA accelerated non-contrast 4D flow MRI of the liver vasculature was applied with acceleration factor R = 5 at 3Tesla. Flow analysis included three-dimensional (3D) blood flow visualization using time-resolved 3D particle traces and semi-quantitative flow pattern grading. Quantitative evaluation entailed peak velocities and net flows throughout the arterial and portal venous (PV) systems. MRI measurements were taken within 24 h before and 4 weeks after TIPS placement. Three-dimensional flow visualization with 4D flow MRI revealed good image quality with minor limitations in PV flow. Quantitative analysis revealed a significant increase in PV flow (562 ± 373 ml/min before vs. 1831 ± 965 ml/min after TIPS), in the hepatic artery (176 ± 132 ml/min vs. 354 ± 140 ml/min) and combined flow in splenic and superior mesenteric arteries (770 ml/min vs. 1064 ml/min). Shunt-flow assessment demonstrated stenoses in two patients confirmed and treated at TIPS revision. Four-dimensional flow MRI might have the potential to give new information about the effect of TIPS placement on hepatic perfusion. It may explain some unexpected findings in clinical observation studies. (orig.)

  3. Transfer function analysis for the assessment of cerebral autoregulation using spontaneous oscillations in blood pressure and cerebral blood flow

    NARCIS (Netherlands)

    Abeelen, A.S.S. van den; Beek, A.H. van; Slump, C.H.; Panerai, R.B.; Claassen, J.A.H.R.

    2014-01-01

    Cerebral autoregulation (CA) is a key mechanism to protect the brain against excessive fluctuations in blood pressure (BP) and maintain cerebral blood flow. Analyzing the relationship between spontaneous BP and cerebral blood flow velocity (CBFV) using transfer function analysis is a widely used tec

  4. Skin temperature and subcutaneous adipose blood flow in man

    DEFF Research Database (Denmark)

    Astrup, A; Bülow, J; Madsen, J

    1980-01-01

    The abdominal subcutaneous adipose tissue blood flow (ATBF) was measured bilaterally by the 133Xe washout method. At one side of the skin (epicutaneous) temperature was varied with a temperature blanket, the other side served as control. There was a significant (P less than 0.001) positive...... correlation between skin temperature and ATBF. In the range from 25 to 37 degrees CATBF increased 9% of the control flow on average per centigrade increase in skin temperature. ATBF at the control side was uninfluenced by the contralateral variations in skin temperature. Although no better correlation could...

  5. An immersed-boundary method for modeling flow of deformable blood cells in complex geometry

    Science.gov (United States)

    Balogh, Peter; Bagchi, Prosenjit

    2016-11-01

    We present a computational methodology for simulating blood flow at the cellular scale in highly complex geometries, such as microvascular networks. Immersed boundary methods provide the foundation for our approach, as they allow modeling flows in arbitrary geometries, in addition to resolving the large deformation and dynamics of individual blood cell with high fidelity. Different simulation components are seamlessly integrated into the present methodology that can simultaneously model stationary rigid boundaries of arbitrary and complex shape, moving rigid bodies, and highly deformable interfaces of blood cells that are governed by non-linear elasticity. This permits physiologically realistic simulations of blood cells flowing in complex microvascular networks characterized by multiple bifurcating and merging vessels. The methodology is validated against analytical theory, experimental data, and previous numerical results. We then demonstrate the capabilities of the methodology by simulating deformable blood cells and heterogeneous cell suspensions flowing in both physiologically realistic microvascular networks and geometrically intricate microfluidic devices. The methodology offers the potential of scaling up to large microvascular networks at organ levels. Funded by NSF CBET 1604308.

  6. Quantitative flow and velocity measurements of pulsatile blood flow with 4D-DSA

    Science.gov (United States)

    Shaughnessy, Gabe; Hoffman, Carson; Schafer, Sebastian; Mistretta, Charles A.; Strother, Charles M.

    2017-03-01

    Time resolved 3D angiographic data from 4D DSA provides a unique environment to explore physical properties of blood flow. Utilizing the pulsatility of the contrast waveform, the Fourier components can be used to track the waveform motion through vessels. Areas of strong pulsatility are determined through the FFT power spectrum. Using this method, we find an accuracy from 4D-DSA flow measurements within 7.6% and 6.8% RMSE of ICA PCVIPR and phantom flow probe validation measurements, respectively. The availability of velocity and flow information with fast acquisition could provide a more quantitative approach to treatment planning and evaluation in interventional radiology.

  7. Unsteady magnetohydrodynamic blood flow through irregular multi-stenosed arteries.

    Science.gov (United States)

    Mustapha, Norzieha; Amin, Norsarahaida; Chakravarty, Santabrata; Mandal, Prashanta Kumar

    2009-10-01

    Flow of an electrically conducting fluid characterizing blood through the arteries having irregular shaped multi-stenoses in the environment of a uniform transverse magnetic-field is analysed. The flow is considered to be axisymmetric with an outline of the irregular stenoses obtained from a three-dimensional casting of a mild stenosed artery, so that the physical problem becomes more realistic from the physiological point of view. The marker and cell (MAC) and successive-over-relaxation (SOR) methods are respectively used to solve the governing unsteady magnetohydrodynamic (MHD) equations and pressure-Poisson equation quantitatively and to observe the flow separation. The results obtained show that the flow separates mostly towards the downstream of the multi-stenoses. However, the flow separation region keeps on shrinking with the increasing intensity of the magnetic-field which completely disappears with sufficiently large value of the Hartmann number. The present observations certainly have some clinical implications relating to magnetotherapy which help reducing the complex flow separation zones causing flow disorder leading to the formation and progression of the arterial diseases.

  8. Autoregulation of cerebral blood flow in experimental focal brain ischemia.

    Science.gov (United States)

    Dirnagl, U; Pulsinelli, W

    1990-05-01

    The relationship between systemic arterial pressure (SAP) and neocortical microcirculatory blood-flow (CBF) in areas of focal cerebral ischemia was studied in 15 spontaneously hypertensive rats (SHRs) anesthetized with halothane (0.5%). Ischemia was induced by ipsilateral middle cerebral artery/common carotid artery occlusion and CBF was monitored continuously in the ischemic territory using laser-Doppler flowmetry during manipulation of SAP with I-norepinephrine (hypertension) or nitroprusside (hypotension). In eight SHRs not subjected to focal ischemia, we demonstrated that 0.5% halothane and the surgical manipulations did not impair autoregulation. Autoregulation was partly preserved in ischemic brain tissue with a CBF of greater than 30% of preocclusion values. In areas where ischemic CBF was less than 30% of preocclusion values, autoregulation was completely lost. Changes in SAP had a greater influence on CBF in tissue areas where CBF ranged from 15 to 30% of baseline (9% change in CBF with each 10% change in SAP) than in areas where CBF was less than 15% of baseline (6% change in CBF with each 10% change in SAP). These findings demonstrate that the relationship between CBF and SAP in areas of focal ischemia is highly dependent on the severity of ischemia. Autoregulation is lost in a gradual manner until CBF falls below 30% of normal. In areas without autoregulation, the slope of the CBF/SAP relationship is inversely related to the degree of ischemia.

  9. Cerebral blood flow in sickle cell cerebrovascular disease

    Energy Technology Data Exchange (ETDEWEB)

    Huttenlocher, P.R.; Moohr, J.W.; Johns, L.; Brown, F.D.

    1984-05-01

    Cerebral blood flow (CBF) has been studied by the xenon-133 (/sup 133/Xe) inhalation method in 16 children with suspected sickle cell cerebrovascular disease. Abnormalities consisting of decreases in total, hemispheral, or regional CBF were found in 17 of 26 studies. Eleven studies performed immediately after stroke, transient ischemic attack, or depression of state of alertness showed abnormalities. In addition to confirming regional cerebrovascular insufficiency in children with stroke due to major cerebral artery occlusion, the method detected diffuse decrease in CBF in children with stupor, coma, and seizures who had normal angiographic findings. In contrast, six of seven studies obtained after exchange transfusion or during maintenance on hypertransfusion therapy showed normal findings. The difference between results in patients with acute neurologic disturbances and those receiving transfusion therapy was statistically significant (P less than .005). The data indicate that the /sup 133/Xe method reliably demonstrates cerebrovascular impairment in sickle cell disease. They also suggest that CBF changes in patients with sickle cell disease can be reversed by exchange transfusion and by hypertransfusion therapy. The /sup 133/Xe CBF method may be useful for following up children with sickle cell disease who are at high risk for recurrent stroke.

  10. A computational approach to modeling cellular-scale blood flow in complex geometry

    Science.gov (United States)

    Balogh, Peter; Bagchi, Prosenjit

    2017-04-01

    We present a computational methodology for modeling cellular-scale blood flow in arbitrary and highly complex geometry. Our approach is based on immersed-boundary methods, which allow modeling flows in arbitrary geometry while resolving the large deformation and dynamics of every blood cell with high fidelity. The present methodology seamlessly integrates different modeling components dealing with stationary rigid boundaries of complex shape, moving rigid bodies, and highly deformable interfaces governed by nonlinear elasticity. Thus it enables us to simulate 'whole' blood suspensions flowing through physiologically realistic microvascular networks that are characterized by multiple bifurcating and merging vessels, as well as geometrically complex lab-on-chip devices. The focus of the present work is on the development of a versatile numerical technique that is able to consider deformable cells and rigid bodies flowing in three-dimensional arbitrarily complex geometries over a diverse range of scenarios. After describing the methodology, a series of validation studies are presented against analytical theory, experimental data, and previous numerical results. Then, the capability of the methodology is demonstrated by simulating flows of deformable blood cells and heterogeneous cell suspensions in both physiologically realistic microvascular networks and geometrically intricate microfluidic devices. It is shown that the methodology can predict several complex microhemodynamic phenomena observed in vascular networks and microfluidic devices. The present methodology is robust and versatile, and has the potential to scale up to very large microvascular networks at organ levels.

  11. Case with stenosis of internal carotid artery detected as a region of decreased blood flow by Tc-99m HMPAO cerebral blood flow scintigraphy

    Energy Technology Data Exchange (ETDEWEB)

    Hayashida, K.; Nishimura, T.; Uehara, T.; Imakita, S.; Yokota, I.; Ogura, H.; Oka, H.; Hayashi, M.; Kikuchi, H.

    1987-04-01

    Tc-99m hexamethylpropyleneamine oxime (= HMPAO) is expected to be an excellent agent as blood flow tracer of brain because it passes through blood brain barrier and is retained in brain parenchyma for several hours. Tc-99m HMPAO scintigraphy was applied to a patient complaining of transient ischemic attack without neurological findings. Left hemispheric hypoperfusion was detected by Tc-99m HMPAO cerebral blood flow scintigraphy. Although it was normal in CT and MRI, it was proved to be a 99 % stenosis of left internal carotid artery by digital subtraction angiography. Tc-99m HMPAO cerebral blood flow scintigraphy is useful for detecting abnormality of cerebral blood flow.

  12. Clitoral blood flow increases following vaginal pressure stimulation.

    Science.gov (United States)

    Lavoisier, P; Aloui, R; Schmidt, M H; Watrelot, A

    1995-02-01

    The vascular responses of clitoral arteries to vaginal pressure stimulation in 10 volunteer women were evaluated by Doppler ultrasonography. Pressure stimulations (20-160 mm Hg) along the lower third of the vagina increased blood velocity and flow into clitoral arteries in 9 of the 10 women. The latency and duration of the Doppler responses ranged from 0.1 to 1.6 sec and from 3.2 to 9.5 sec, respectively, and the response was associated with a blood flow increase of 4 to 11 times the baseline prestimulation level. This response parallels that recorded in the cavernous arteries in men when a similar range of pressure stimulations are applied to the glans penis. Similar responses evoked in the male and female suggest a sexual synergy that may occur during intercourse in that such physiological responses and reflexes may be reciprocally reinforced.

  13. Pressure Gradient Estimation Based on Ultrasonic Blood Flow Measurement

    Science.gov (United States)

    Nitta, Naotaka; Homma, Kazuhiro; Shiina, Tsuyoshi

    2006-05-01

    Mechanical load to the blood vessel wall, such as shear stress and pressure, which occurs in blood flow dynamics, contribute greatly to plaque rupture in arteriosclerosis and to biochemical activation of endothelial cells. Therefore, noninvasive estimations of these mechanical loads are able to provide useful information for the prevention of vascular diseases. Although the pressure is the dominant component of mechanical load, for practical purposes, the pressure gradient is also often important. So far, we have investigated the estimation of the kinematic viscosity coefficient using a combination of the Navier-Stokes equations and ultrasonic velocity measurement. In this paper, a method for pressure gradient estimation using the estimated kinematic viscosity coefficient is proposed. The validity of the proposed method was investigated on the basis of the analysis with the data obtained by computer simulation and a flow phantom experiment. These results revealed that the proposed method can provide a valid estimation of the pressure gradient.

  14. Chronic intestinal ischemia and splanchnic blood-flow

    DEFF Research Database (Denmark)

    Zacho, Helle Damgaard; Henriksen, Jens Henrik; Abrahamsen, Jan

    2013-01-01

    -1390), and this value increased significantly to 1787 mL/min after the meal in healthy volunteers (P ...-induced increase in SBF was equal to 282 mL/min + 5.4 mL/min × bodyweight, (P = 0.025). The SO₂U in healthy volunteers and patients was 50.7 mL/min and 48.0 mL/min, respectively, and these values increased to 77.5 mL/min and 75 mL/min postprandially, respectively. Both baseline and postprandial SO₂U were directly......AIM: To determine the splanchnic blood flow and oxygen uptake in healthy-subjects and patients and to relate the findings to body-composition. METHODS: The total splanchnic blood flow (SBF) and oxygen uptake (SO₂U) were measured in 20 healthy volunteers (10 women) and 29 patients with suspected...

  15. Subcutaneous blood flow in early male pattern baldness

    Energy Technology Data Exchange (ETDEWEB)

    Klemp, P.; Peters, K.; Hansted, B.

    1989-05-01

    The subcutaneous blood flow (SBF) was measured by the /sup 133/Xe washout method in the scalp of 14 patients with early male pattern baldness. Control experiments were performed in 14 normal haired men matched for age. The SBF in the scalp of the normal individuals was about 10 times higher than previously reported SBF values in other anatomical regions. In patients with early male pattern baldness, SBF was 2.6 times lower than the values found in the normal individuals (13.7 +/- 9.6 vs 35.7 +/- 10.5 ml/100 g/min-1). This difference was statistically significant (p much less than 0.001). A reduced nutritive blood flow to the hair follicles might be a significant event in the pathogenesis of early male pattern baldness.

  16. Cerebral autoregulation control of blood flow in the brain

    CERN Document Server

    Payne, Stephen

    2016-01-01

    This Brief provides a comprehensive introduction to the control of blood flow in the brain. Beginning with the basic physiology of autoregulation, the author goes on to discuss measurement techniques, mathematical models, methods of analysis, and relevant clinical conditions, all within this single volume. The author draws together this disparate field, and lays the groundwork for future research directions. The text gives an up-to-date review of the state of the art in cerebral autoregulation, which is particularly relevant as cerebral autoregulation moves from the laboratory to the bedside. Cerebral Autoregulation will be useful to researchers in the physical sciences such as mathematical biology, medical physics, and biomedical engineering whose work is concerned with the brain. Researchers in the medical sciences and clinicians dealing with the brain and blood flow, as well as industry professionals developing techniques such as ultrasound, MRI, and CT will also find this Brief of interest.

  17. The nucleus of endothelial cell as a sensor of blood flow direction

    Directory of Open Access Journals (Sweden)

    Eugene Tkachenko

    2013-08-01

    Hemodynamic shear stresses cause endothelial cells (ECs to polarize in the plane of the flow. Paradoxically, under strong shear flows, ECs disassemble their primary cilia, common sensors of shear, and thus must use an alternative mechanism of sensing the strength and direction of flow. In our experiments in microfluidic perfusion chambers, confluent ECs developed planar cell polarity at a rate proportional to the shear stress. The location of Golgi apparatus and microtubule organizing center was biased to the upstream side of the nucleus, i.e. the ECs polarized against the flow. These in vitro results agreed with observations in murine blood vessels, where EC polarization against the flow was stronger in high flow arteries than in veins. Once established, flow-induced polarization persisted over long time intervals without external shear. Transient destabilization of acto-myosin cytoskeleton by inhibition of myosin II or depolymerization of actin promoted polarization of EC against the flow, indicating that an intact acto-myosin cytoskeleton resists flow-induced polarization. These results suggested that polarization was induced by mechanical displacement of EC nuclei downstream under the hydrodynamic drag. This hypothesis was confirmed by the observation that acute application of a large hydrodynamic force to ECs resulted in an immediate downstream displacement of nuclei and was sufficient to induce persistent polarization. Taken together, our data indicate that ECs can sense the direction and strength of blood flow through the hydrodynamic drag applied to their nuclei.

  18. Effects of Wrist Posture and Fingertip Force on Median Nerve Blood Flow Velocity

    Science.gov (United States)

    Wilson, Katherine E.; Tat, Jimmy

    2017-01-01

    Purpose. The purpose of this study was to assess nerve hypervascularization using high resolution ultrasonography to determine the effects of wrist posture and fingertip force on median nerve blood flow at the wrist in healthy participants and those experiencing carpal tunnel syndrome (CTS) symptoms. Methods. The median nerves of nine healthy participants and nine participants experiencing symptoms of CTS were evaluated using optimized ultrasonography in five wrist postures with and without a middle digit fingertip press (0, 6 N). Results. Both wrist posture and fingertip force had significant main effects on mean peak blood flow velocity. Blood flow velocity with a neutral wrist (2.87 cm/s) was significantly lower than flexed 30° (3.37 cm/s), flexed 15° (3.27 cm/s), and extended 30° (3.29 cm/s). Similarly, median nerve blood flow velocity was lower without force (2.81 cm/s) than with force (3.56 cm/s). A significant difference was not found between groups. Discussion. Vascular changes associated with CTS may be acutely induced by nonneutral wrist postures and fingertip force. This study represents an early evaluation of intraneural blood flow as a measure of nerve hypervascularization in response to occupational risk factors and advances our understanding of the vascular phenomena associated with peripheral nerve compression.

  19. Study on relationship between perifollicular blood flow and in vitro fertilization-embryo transfer

    Institute of Scientific and Technical Information of China (English)

    Yan Zhang; Jing Yang; Wangming Xu

    2008-01-01

    Objective: To study the relationship between perifoUicular blood flow and follicule development, oocyte maturing rate, fertilizing rate, cleaving rate, embryo quality and the outcomes of embryo transfer. Methods: The samples were selected from 66 suffers who underwent in vitro fertilization(IVF)or intracytoplasmic sperm injection(ICSI). Eeach patients' perifollicular blood flow(diameter≥12mm )was estimated on the day of human chorionic gonadotropin(HCG)administration. Results:Among 66 cycles, 26(39.4%) cycles resulted in pregnancy, perifollicular blood flow resistance index(Rl), peak systolic velocity/end diastasis velocity(S/D) of non-preg-nant group was significantly higher than that of the pregnant group (P < 0.004). When RI<0.49, the pregnancy rates, fecundation rates, fertilization rates, metaphase numbers for the of second meiosis oocytes increased evidently(P<0.05), but there were no statistical difference in gonadotropin dosage, cycle frequency, infertility years, ages, estradiol(E2)on the day of HCG administration,numbers of oocyet retrieved and high-quality embryo rates (P > 0.05 ). There were no statistical difference between non-pregnant group and pregnant group in S and D (P>0.05). There was no correlation between periFollicular blood flow RI and follicular diameter by linear regression analysis. Conclusion:Our study shows that perifollicular blood flow RI and S/D are effective indices of predicting the pregnancy outcome of IVF-ET.

  20. Effects of Wrist Posture and Fingertip Force on Median Nerve Blood Flow Velocity

    Directory of Open Access Journals (Sweden)

    Katherine E. Wilson

    2017-01-01

    Full Text Available Purpose. The purpose of this study was to assess nerve hypervascularization using high resolution ultrasonography to determine the effects of wrist posture and fingertip force on median nerve blood flow at the wrist in healthy participants and those experiencing carpal tunnel syndrome (CTS symptoms. Methods. The median nerves of nine healthy participants and nine participants experiencing symptoms of CTS were evaluated using optimized ultrasonography in five wrist postures with and without a middle digit fingertip press (0, 6 N. Results. Both wrist posture and fingertip force had significant main effects on mean peak blood flow velocity. Blood flow velocity with a neutral wrist (2.87 cm/s was significantly lower than flexed 30° (3.37 cm/s, flexed 15° (3.27 cm/s, and extended 30° (3.29 cm/s. Similarly, median nerve blood flow velocity was lower without force (2.81 cm/s than with force (3.56 cm/s. A significant difference was not found between groups. Discussion. Vascular changes associated with CTS may be acutely induced by nonneutral wrist postures and fingertip force. This study represents an early evaluation of intraneural blood flow as a measure of nerve hypervascularization in response to occupational risk factors and advances our understanding of the vascular phenomena associated with peripheral nerve compression.

  1. High-performance liquid chromatography of the renal blood flow marker p-aminohippuric acid (PAH) and its metabolite N-acetyl PAH improves PAH clearance measurements.

    Science.gov (United States)

    Decosterd, L A; Karagiannis, A; Roulet, J M; Bélaz, N; Appenzeller, M; Buclin, T; Vogel, P; Biollaz, J

    1997-12-05

    PAH (N-(4-aminobenzoyl)glycin) clearance measurements have been used for 50 years in clinical research for the determination of renal plasma flow. The quantitation of PAH in plasma or urine is generally performed by colorimetric method after diazotation reaction but the measurements must be corrected for the unspecific residual response observed in blank plasma. We have developed a HPLC method to specifically determine PAH and its metabolite NAc-PAH using a gradient elution ion-pair reversed-phase chromatography with UV detection at 273 and 265 nm, respectively. The separations were performed at room temperature on a ChromCart (125 mmx4 mm I.D.) Nucleosil 100-5 microm C18AB cartridge column, using a gradient elution of MeOH-buffer pH 3.9 1:99-->15:85 over 15 min. The pH 3.9 buffered aqueous solution consisted in a mixture of 375 ml sodium citrate-citric acid solution (21.01 g citric acid and 8.0 g NaOH per liter), added up with 2.7 ml H3PO4 85%, 1.0 g of sodium heptanesulfonate and completed ad 1000 ml with ultrapure water. The N-acetyltransferase activity does not seem to notably affect PAH clearances, although NAc-PAH represents 10.2+/-2.7% of PAH excreted unchanged in 12 healthy subjects. The performance of the HPLC and the colorimetric method have been compared using urine and plasma samples collected from healthy volunteers. Good correlations (r=0.94 and 0.97, for plasma and urine, respectively) are found between the results obtained with both techniques. However, the colorimetric method gives higher concentrations of PAH in urine and lower concentrations in plasma than those determined by HPLC. Hence, both renal (ClR) and systemic (Cls) clearances are systematically higher (35.1 and 17.8%, respectively) with the colorimetric method. The fraction of PAH excreted by the kidney ClR/ClS calculated from HPLC data (n=143) is, as expected, always 1). In conclusion, HPLC not only enables the simultaneous quantitation of PAH and NAc-PAH, but may also provide more

  2. Efficacy, Safety and Mechanisms of Blood Flow Restricted Exercise

    Science.gov (United States)

    Ploutz-Snyder, Lori

    2009-01-01

    This 20 minute talk will review studies in the peer-reviewed literature related to the effectiveness of blood flow restricted exercise as an exercise training program. There is controversy regarding the talk with cover the effectiveness of various exercise protocols and these differences will be compared and contrasted. Unpublished data from my laboratory at Syracuse University will be presented (see other abstract), as well as some unpublished work from the labs of Manini, Clark and Rasmussen (none are NASA funded).

  3. High Blood Pressure: Medicines to Help You

    Science.gov (United States)

    ... names are given for the drugs in each group.Find your drug. Then read some basic information about your kind of drug. Types of High Blood Pressure Medicines ACE Inhibitors Beta Blockers Calcium Channel Blockers ...

  4. High Blood Pressure May Hike Dementia Risk

    Science.gov (United States)

    ... fullstory_161398.html High Blood Pressure May Hike Dementia Risk New statement from American Heart Association warns ... in middle age, might open the door to dementia, the American Heart Association warns in a new ...

  5. Effect of red blood cell rigidity on tumor blood flow: increase in viscous resistance during hyperglycemia.

    Science.gov (United States)

    Sevick, E M; Jain, R K

    1991-05-15

    Elevated glucose level and low pH have been shown to increase red blood cell (RBC) rigidity. This increased rigidity has been proposed as one factor which mediates the tumor blood flow (TBF) reduction during hyperglycemia by (a) causing RBC entrapment and hence increasing geometric resistance and (b) increasing viscous resistance to blood flow. However, due to the inability to measure these resistances in vivo in tumors directly, the relative contribution of RBC rigidity in TBF reduction has not been quantified. In the present study, blood flow resistance was measured in "tissue-isolated" mammary adenocarcinoma R3230AC perfused ex vivo with (a) normally deformable, (b) glutaraldehyde-hardened, and (c) glucose-incubated RBC suspensions. Flow resistance measured during tumor perfusion with Krebs-Henseleit buffer prior to and following perfusion with the glutaraldehyde-hardened RBC suspensions showed no significant change, suggesting constant geometric resistance and lack of RBC entrapment. Instead, our measurements indicated increased viscous resistance with loss of deformability due to glutaraldehyde and glucose incubation even though glucose incubation did not significantly alter the apparent blood viscosity measured in vitro. Thus, the TBF reduction during hyperglycemia may be due to subtle changes in RBC deformability. These results suggest the development of strategies to increase the delivery of drugs or oxygen must take into account any changes in intratumor viscous resistance. For example, the increase in the oxygen-carrying capacity of blood using RBC transfusion or fluorocarbon emulsions may be offset by the increase in viscous resistance and the corresponding reduction in TBF.

  6. Predicting Endometrium Receptivity with Parameters of Spiral Artery Blood Flow

    Institute of Scientific and Technical Information of China (English)

    GONG Xuehao; LI Quanshui; ZHANG Qingping; ZHU Guijin

    2005-01-01

    Summary: In order To evaluate whether the parameters of spiral artery blood flow, as measured by transvaginal color Doppler, may be used to assess endometrium receptivity prior to embryo transfer (ET), a retrospective study of 94 infertile women who had undergone ART treatments with different outcomes (pregnant or nonpregnant) was done. Subendometrial blood flow was evaluated. The resistance index (RI), systolic/diastolic ratio (S/D) and pulsatility index (PI) were significantly lower in those who achieved pregnancy as compared with those who did not: 0.62±0.04 vs 0.68±0.04 (P<0.001), 2.66±0.33 vs 3.19±0.39 (P<0.01) and 1.15±0.17 vs 1.34±0.22 (P<0.05), respectively. Furthermore, when RI>0.72, PI>1.6, and S/D>3.6, no pregnancy occurred. These data suggest that the parameters of spiral artery blood flow could be used as a new assay in predicting endometrial receptivity before ET.

  7. Ocular Blood Flow Measured Noninvasively in Zero Gravity

    Science.gov (United States)

    Ansari, Rafat R.; Manuel, Francis K.; Geiser, Martial; Moret, Fabrice; Messer, Russell K.; King, James F.; Suh, Kwang I.

    2003-01-01

    In spaceflight or a reduced-gravity environment, bodily fluids shift to the upper extremities of the body. The pressure inside the eye, or intraocular pressure, changes significantly. A significant number of astronauts report changes in visual acuity during orbital flight. To date this remains of unknown etiology. Could choroidal engorgement be the primary mechanism and a change in the curvature or shape of the cornea or lens be the secondary mechanism for this change in visual acuity? Perfused blood flow in the dense meshwork of capillaries of the choroidal tissue (see the preceding illustration) provides necessary nutrients to the outer layers of the retina (photoreceptors) to keep it healthy and maintain good vision. Unlike the vascular system, the choroid has no baroreceptors to autoregulate fluid shifts, so it can remain engorged, pushing the macula forward and causing a hyperopic (farsighted) shift of the eye. Experiments by researchers at the NASA Glenn Research Center could help answer this question and facilitate planning for long-duration missions. We are investigating the effects of zero gravity on the choroidal blood flow of volunteer subjects. This pilot project plans to determine if choroidal blood flow is autoregulated in a reduced-gravity environment.

  8. Cerebral blood flow is reduced in patients with sepsis syndrome

    Energy Technology Data Exchange (ETDEWEB)

    Bowton, D.L.; Bertels, N.H.; Prough, D.S.; Stump, D.A.

    1989-05-01

    The relationship between sepsis-induced CNS dysfunction and changes in brain blood flow remains unknown, and animal studies examining the influence of sepsis on cerebral blood flow (CBF) do not satisfactorily address that relationship. We measured CBF and cerebrovascular reactivity to CO/sub 2/ in nine patients with sepsis syndrome using the /sup 133/Xe clearance technique. Mean CBF was 29.6 +/- 15.8 (SD) ml/100 g.min, significantly lower than the normal age-matched value in this laboratory of 44.9 +/- 6.2 ml/100 g.min (p less than .02). This depression did not correlate with changes in mean arterial pressure. Despite the reduction in CBF, the specific reactivity of the cerebral vasculature to changes in CO/sub 2/ was normal, 1.3 +/- 0.9 ml/100 g.min/mm Hg. Brain blood flow is reduced in septic humans; the contribution of this reduction to the metabolic and functional changes observed in sepsis requires further study.

  9. Coronary blood flow in patients with cardiac syndrome X.

    Science.gov (United States)

    Sen, Nihat; Tavil, Yusuf; Yazici, Hüseyin Uğur; Abacl, Adnan; Cengel, Atiye

    2007-02-01

    Epicardial coronary arteries are normal in patients with cardiac syndrome X. It is, however, unclear whether there is an abnormality at the level of microvascular circulation. In this study, our aim was to evaluate the epicardial coronary blood flow and myocardial perfusion in patients with cardiac syndrome X. Two hundred and three patients (mean age 53+/-10 years, 85 men) were included in the study. The diagnosis of cardiac syndrome X was made in patients who had a complaint of typical anginal chest pain and had ischemic findings on either myocardial perfusion scintigraphy or a treadmill exercise test, and whose coronary angiograms did not reveal any pathology. Fifty patients (mean age 54+/-11 years, 24 men) who had a complaint of typical anginal chest pain and had a normal myocardial perfusion test and normal coronary arteries were recruited as the control group. Epicardial coronary blood flow was evaluated with the thrombolysis in myocardial infarction frame count method and myocardial perfusion was evaluated with the myocardial blush grade method. A myocardial blush grade of 0.05). We found that the epicardial coronary blood flow, as assessed by thrombolysis in myocardial infarction frame count, and myocardial perfusion, as assessed by myocardial blush grade, were normal in patients with cardiac syndrome X.

  10. Blood flow distribution with adrenergic and histaminergic antagonists

    Energy Technology Data Exchange (ETDEWEB)

    Baker, C.H.; Davis, D.L.; Sutton, E.T.

    1989-03-01

    Superficial fibular nerve stimulation (SFNS) causes increased pre- and post-capillary resistances as well as increased capillary permeability in the dog hind paw. These responses indicate possible adrenergic and histaminergic interactions. The distribution of blood flow between capillaries and arteriovenous anastomoses (AVA) may depend on the relative effects of these neural inputs. Right hind paws of anesthetized heparinized dogs were vascularly and neurally isolated and perfused with controlled pressure. Blood flow distribution was calculated from the venous recovery of 85Sr-labeled microspheres (15 microns). The mean transit times of 131I-albumin and 85Sr-labeled microspheres were calculated. The effects of adrenergic and histaminergic antagonists with and without SFNS were determined. Phentolamine blocked the entire response to SFNS. Prazosin attenuated increases in total and AVA resistance. Yohimbine prevented increased total resistance, attenuated the AVA resistance increase, and revealed a decrease in capillary circuit resistance. Pyrilamine attenuated total resistance increase while SFNS increased capillary and AVA resistances. Metiamide had no effect on blood flow distribution with SFNS. The increase in AVA resistance with SFNS apparently resulted from a combination of alpha 1 and alpha 2 receptor stimulation but not histaminergic effects.

  11. Pulsed photoacoustic Doppler flow measurements in blood-mimicking phantoms

    Science.gov (United States)

    Brunker, J.; Beard, P.

    2011-03-01

    The feasibility of making spatially resolved measurements of blood flow using pulsed photoacoustic Doppler techniques has been explored. Doppler time shifts were quantified via cross-correlation of pairs of photoacoustic waveforms generated within a blood-simulating phantom using pairs of laser light pulses. The photoacoustic waves were detected using a focussed or planar PZT ultrasound transducer. For each flow measurement, a series of 100 waveform pairs was collected. Previous data processing methods involved rejection of poorly correlated waveform pairs; the modal velocity value and standard deviation were then extracted from the selected distribution of velocity measurements. However, the data selection criteria used in this approach is to some extent arbitrary. A new data analysis protocol, which involves averaging the 100 cross-correlation functions and thus uses all of the measured data, has been designed in order to prevent exclusion of outliers. This more rigorous approach has proved effective for quantifying the linear motion of micron-scale absorbers imprinted on an acetate sheet moving with velocities in the range 0.14 to 1.25 ms-1. Experimental parameters, such as the time separation between the laser pulses and the transducer frequency response, were evaluated in terms of their effect on the accuracy, resolution and range of measurable velocities. The technique was subsequently applied to fluid phantoms flowing at rates less than 5 mms-1 along an optically transparent tube. Preliminary results are described for three different suspensions of phenolic resin microspheres, and also for whole blood. Velocity information was obtained even under non-optimal conditions using a low frequency transducer and a low pulse repetition frequency. The distinguishing advantage of pulsed rather than continuous-wave excitation is that spatially resolved velocity measurements can be made. This offers the prospect of mapping flow within the microcirculation and thus

  12. Quantification of blood flow and topology in developing vascular networks.

    Directory of Open Access Journals (Sweden)

    Astrid Kloosterman

    Full Text Available Since fluid dynamics plays a critical role in vascular remodeling, quantification of the hemodynamics is crucial to gain more insight into this complex process. Better understanding of vascular development can improve prediction of the process, and may eventually even be used to influence the vascular structure. In this study, a methodology to quantify hemodynamics and network structure of developing vascular networks is described. The hemodynamic parameters and topology are derived from detailed local blood flow velocities, obtained by in vivo micro-PIV measurements. The use of such detailed flow measurements is shown to be essential, as blood vessels with a similar diameter can have a large variation in flow rate. Measurements are performed in the yolk sacs of seven chicken embryos at two developmental stages between HH 13+ and 17+. A large range of flow velocities (1 µm/s to 1 mm/s is measured in blood vessels with diameters in the range of 25-500 µm. The quality of the data sets is investigated by verifying the flow balances in the branching points. This shows that the quality of the data sets of the seven embryos is comparable for all stages observed, and the data is suitable for further analysis with known accuracy. When comparing two subsequently characterized networks of the same embryo, vascular remodeling is observed in all seven networks. However, the character of remodeling in the seven embryos differs and can be non-intuitive, which confirms the necessity of quantification. To illustrate the potential of the data, we present a preliminary quantitative study of key network topology parameters and we compare these with theoretical design rules.

  13. Study of intracardiac blood flow by MRI using gradient echo method

    Energy Technology Data Exchange (ETDEWEB)

    Ohnishi, Shusaku; Fukui, Sugao; Atsumi, Chisato; Morita, Ruriko; Kusuoka, Hideo; Fujii, Kenshi; Kitabatake, Akira; Takizawa, Osamu.

    1988-06-01

    In order to investigate the possibility of MR imaging for the evaluation of intracardiac blood flow especially valvular regurgitant flow, we obtained MR images using a 1.5 tesla superconductive magnet system (Siemens Medical) in 3 healthy volunteers, 3 patients with hypertrophic cardiomyopathy and 8 patients with valvular heart disease. Rapid FLASH (Fast Low-Angle Shot) imaging technique was applied to collect 11 time frames per section throughout one cardiac cycle in axial, coronal, saggital and oblique sections. Then these sequential frames were displayed in a cine mode on CRT. (1) Intracardiac and intravascular blood flow were visualized with high signal intensity in each frame and cardiac structures such as atria, ventricles, and aorta were also identified in all subjects. (2) Ventricular ejection flow was easily visualized in coronal section as the signal loss in the ascending aorta. Ventricularfilling was visualized in axial and oblique sections as the high signal influx of atrial blood into the ventricle. (3) In 3 patients with aortic regurgitation, regurgitant flow was detected during diastole as the teardrop shaped signal loss originating from aortic valve cusps. (4) Both mitral and tricuspid regurgitant flow were detected during systole as the signal loss in atrium in axial and oblique sections in 2 patients with MR and 2 patients with TR. (5) Pulmonary regurgitant flow was observed in oblique section along the long axis of right ventricular outflow tract. These results indicate that intracardiac forward and regurgitant flow could be identified with rapid FLASH imaging in normal subjects and in patients with valvular heart diseases, and cine mode MR imaging is a useful tool for the evaluation of intracardiac blood flow.

  14. Microscopic Local Measurement of Blood Flow and Oxygen Tension in Brain Microcirculation

    Science.gov (United States)

    Minamitani, Haruyuki; Takahashi, Ryota; Tsukada, Kousuke

    A multi-photonic imaging system was proposed for measuring blood flow velocity, vessel diameter and blood oxygen tension pO2 simultaneously with high spatio-temporal resolution in the parenchymatous organ microcirculation, such as pial tissue, by using a closed cranial window and two light sources. FITC-stained erythrocytes was used to visualize the microcirculation, and the fluorescent image was recorded by a high-speed video camera for measuring blood flow velocity. Oxygen tension pO2 was measured by oxygen-dependent quenching of phosphorescent molecules, Pd-TCPP, in the microvessels after irradiation of second harmonic light of Nd:YAG pulse laser (532nm). Animal experiments were performed for investigation of blood flow dynamics and oxygen diffusion phenomenon during acute cerebral ischemia using photochemical thrombus formation in the closed cranial window of male Wistar rats. Experimental results showed specific and significant blood flow and oxygen diffusion phenomena related to the abnormal organ tissues, from those the proposed technique would contribute to the trasnlational research for the clinical medicine, concerned in the ischemic dysfunction, angiogenisis, tumorgenisis and so on.

  15. Characterization of Transition to Turbulence for Blood in a Straight Pipe Under Steady Flow Conditions.

    Science.gov (United States)

    Biswas, Dipankar; Casey, David M; Crowder, Douglas C; Steinman, David A; Yun, Yang H; Loth, Francis

    2016-07-01

    Blood is a complex fluid that, among other things, has been established to behave as a shear thinning, non-Newtonian fluid when exposed to low shear rates (SR). Many hemodynamic investigations use a Newtonian fluid to represent blood when the flow field of study has relatively high SR (>200 s-1). Shear thinning fluids have been shown to exhibit differences in transition to turbulence (TT) compared to that of Newtonian fluids. Incorrect prediction of the transition point in a simulation could result in erroneous hemodynamic force predictions. The goal of the present study was to compare velocity profiles near TT of whole blood and Newtonian blood analogs in a straight rigid pipe with a diameter 6.35 mm under steady flow conditions. Rheology was measured for six samples of whole porcine blood and three samples of a Newtonian fluid, and the results show blood acts as a shear thinning non-Newtonian fluid. Measurements also revealed that blood viscosity at SR = 200 s-1 is significantly larger than at SR = 1000 s-1 (13.8%, p velocity profiles for blood and Newtonian samples at different flow rates to produce Reynolds numbers (Re) ranging from 1000 to 3300 (based on viscosity at SR = 1000 s-1). Two mathematically defined methods, based on the velocity profile shape change and turbulent kinetic energy (TKE), were used to detect TT. Results show similar parabolic velocity profiles for both blood and the Newtonian fluid for Re velocity profiles for larger Re. The Newtonian fluid had blunt-like velocity profiles starting at Re = 2403 ± 8 which indicated transition. In contrast, blood did not show this velocity profile change until Re = 2871 ± 104. The Newtonian fluid had large velocity fluctuations (root mean square (RMS) > 20%) with a maximum TKE near the pipe center at Re = 2316 ± 34 which indicated transition. In contrast, blood results showed the maximum TKE at Re = 2806 ± 109. Overall, the critical Re was

  16. Relationship between cardiac function and resting cerebral blood flow

    DEFF Research Database (Denmark)

    Henriksen, Otto M; Jensen, Lars T; Krabbe, Katja;

    2014-01-01

    Although both impaired cardiac function and reduced cerebral blood flow are associated with ageing, current knowledge of the influence of cardiac function on resting cerebral blood flow (CBF) is limited. The aim of this study was to investigate the potential effects of cardiac function on CBF. CBF...... and cardiac output were measured in 31 healthy subjects 50-75 years old using magnetic resonance imaging techniques. Mean values of CBF, cardiac output and cardiac index were 43.6 ml per 100 g min(-1), 5.5 l min(-1) and 2.7 l min(-1) m(-2), respectively, in males, and 53.4 ml per 100 g min(-1), 4.3 l min(-1......) and 2.4 l min(-1) m(-2), respectively, in females. No effects of cardiac output or cardiac index on CBF or structural signs of brain ageing were observed. However, fractional brain flow defined as the ratio of total brain flow to cardiac output was inversely correlated with cardiac index (r(2) = 0.22, P...

  17. Occlusion cuff for routine measurement of digital blood pressure and blood flow

    DEFF Research Database (Denmark)

    Lassen, N A; Krähenbühl, B; Hirai, M

    1977-01-01

    A miniaturized blood pressure cuff made of plastic material and applicable to fingers and toes is described. The cuff was compared to rubber cuffs and to bladder-free cuffs. It was found to be more reliable than the former type and much easier to use than the latter type. It is recommended for us...... in conjunction with a mercury-in-Silastic strain gauge for routine measurement of digital blood pressure and blood flow in patients with arterial disease.......A miniaturized blood pressure cuff made of plastic material and applicable to fingers and toes is described. The cuff was compared to rubber cuffs and to bladder-free cuffs. It was found to be more reliable than the former type and much easier to use than the latter type. It is recommended for use...

  18. PERFUSION PRESSURE AND RENAL BLOOD FLOW: THEIR RELATIONSHIP AND DIFFERENCES

    Directory of Open Access Journals (Sweden)

    Carlos G. Musso, MD. PhD.1,2, Manuel Vilas, MD.

    2014-05-01

    Full Text Available The concepts of renal perfusion pressure (RPP and renal blood flow (RBF are usually confused, but although they are intimately related, they are not strictly the same. RPP originates from the minute cardiac volume and is, therefore, the cause of RBF, which generates glomerular filtration and as a consequence, also induces the urinary flow. On the other hand, whereas RPP can be subject to fluctuations, the same happens to RBF though at a much lower level due to the existence of physiological mechanisms, such as self-regulation of the flow and tubule-glomerular feed-back. We conclude that there is a dependence of the RBF in relation with RPP, with the former acting as the final responsible of the glomerular filtration.

  19. Renal blood flow and metabolism after cold ischaemia

    DEFF Research Database (Denmark)

    Henriksen, J H; Petersen, H K

    1984-01-01

    Peroperative measurements of renal blood flow (RBF), renal O2-uptake, and renal venous lactate/pyruvate (L/P) ratio were performed before and after a period of 30-71 min of hypothermic (10-15 degrees C) renal ischaemia in nine patients, undergoing surgery for renal calculi. Before ischaemia, RBF.......01) immediately after re-established perfusion and 36% (P less than 0.02) 30 min later. In one additional patient, who had a short warm ischaemia (8 min), the flow pattern was the same. As arterial pressure remained constant, the reduced RBF signifies an increased renal vascular resistance. Renal O2-uptake...... and renal venous L/P ratio were almost constant, indicating no significant anaerobic processes being involved in the flow response. None of the patients showed any signs of reactive hyperaemia. It is concluded that hypothermic renal ischaemia may be followed by an increased renal vascular resistance even...

  20. Low-Load Resistance Training with Blood Flow Occlusion as a Countermeasure to Disuse Atrophy

    Science.gov (United States)

    Ploutz-Snyder, L. L.; Cook, S. B.

    2009-01-01

    Decreases in strength and neuromuscular function are observed following prolonged disuse. Exercise countermeasures to prevent muscle dysfunction during disuse typically involve high intensity resistance training. The purpose of the study is to evaluate the effectiveness of low-load resistance training with a blood flow occlusion to mitigate muscle loss and dysfunction during 30 days of unilateral lower limb suspension (ULLS).