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Koochaki, Z. B. "Modelling of CO2̲ removal from blood by combined dialyser/oxygenator divices." Thesis, University of Strathclyde, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.382397.
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Alexander, Joseph V. "Long Term Blood Oxygenation Membranes." UKnowledge, 2015. http://uknowledge.uky.edu/cbme_etds/28.
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Hollow fiber membranes are widely used in blood oxygenators to remove carbon dioxide and add oxygen during cardiopulmonary bypass operations. These devices are now widely used off-label by physicians to perform extracorporeal blood oxygenation for patients with lung failure. Unfortunately, the hollow fiber membranes used in these devices fail prematurely due to blood plasma leakage and gas emboli formation.
This project formed ultrathin (~100nm) polymer coatings on polymer hollow fiber membranes. The coatings were intended to “block” existing pores on the exterior surfaces while permitting high gas fluxes. This coating is synthesized using surface imitated control radical polymerization.
The coating was durable and did not peel or degrade. Fibers modified using this coating technique did not substantially degrade the mechanical properties of the membrane. This coating technique prevented blood plasma leakage and gas emboli formation. The coating permitted blood oxygenation and carbon dioxide removal from in a mock circulation module.
Coating formation on polymeric hollow fiber membranes using surface initiated controlled radical polymerization allows for the formation of membranes that have the potential for long term blood oxygenation. This coating technique would allow these long term blood membranes to be produced more inexpensively than currently existing membranes used for long term use.
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Bommel, Jasper van. "Hemodilution, blood transfusion, and regional oxygenation." [S.l. : Amsterdam : s.n.] ; Universiteit van Amsterdam [Host], 2001. http://dare.uva.nl/document/59608.
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Gardener, Alexander Graeme. "In-vivo measurement of blood oxygenation using MR." Thesis, University of Nottingham, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.422749.
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Sivaramakrishnan, Mathangi. "In vivo blood oxygenation level measurements using photoacoustic microscopy." Texas A&M University, 2003. http://hdl.handle.net/1969.1/5851.
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We investigate the possibility of extracting accurate functional information such
as local blood oxygenation level using multi-wavelength photoacoustic measurements.
Photoacoustic microscope is utilized to acquire images of microvasculature in smallanimal
skin. Owing to endogenous optical contrast, optical spectral information obtained
from spectral photoacoustic measurements are successfully inverted to yield oxygenation
level in blood. Analysis of error propagation from photoacoustic measurements to
inverted quantities showed minimum inversion error in the optical wavelength region of
570-600 nm. To obtain accurate and vessel size independent blood oxygenation
measurements, transducers with central frequency of more than 25 MHz are needed for
the optical region of 570-600 nm used in this study. The effect of transducer focal
position on accuracy of blood oxygenation level quantification was found to be
negligible. To obtain accurate measurements in vivo, one needs to compensate for
factors such as spectral dependent optical attenuation.
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Smith, Nina A. "Measurement of Red Blood Cell Oxygenation State by Magnetophoresis." Cleveland State University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=csu1568890258014352.
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Ullah, Tania. "Development of a microfluidic device for blood oxygenation by photocatalysis." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/50579.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2009.<br>Includes bibliographical references (p. 85-87).<br>Recent statistics provided by the American Lung Association assert that over 400,000 Americans die every year from lung disorders and more than 35 million are now living with symptoms of lung disease. Mortality rates of heart disease and certain cancers have declined in recent years partly due to improvements in diagnostic testing and the development of targeted medical technologies. Such improvements have not translated over to the treatment of lung disease and lung cancer. The goal of the artificial respiration project is to create a self-contained, mobile oxygen supply that is suitable for implantation and that can potentially replace acute or chronically disabled lungs. A novel microfluidic device for the oxygenation of whole blood has been developed. The device couples a semiconductor, titanium dioxide (TiO₂), thin film that generates oxygen through photocatalysis with a microfluidic network that facilitates diffusion of the dissolved oxygen to red blood cells. While true pulmonary respiration relies on passive diffusion of oxygen gas from the environment to the blood, the proposed device differs in that it generates oxygen directly from the water in blood plasma. This thesis focuses on the work done to fabricate and characterize the semiconductor photocatalyst, design the integrated microfluidic chip, and validate its capacity to oxygenate blood in real-time. Blood oxygenation experiments show that the microfluidic device exhibiting the best performance produced 4.06 mL of oxygen per 100 mL of blood, nearly two-thirds of the oxygen transferred in the lung.<br>(cont.) The flux of oxygen at the photocatalyst surface was 1.11 x 10-3 mmol O₂/ (cm² - min). The O₂ flux is nearly two orders of magnitude larger than that of any other fluidic device for blood oxygenation to date. The results from the proof-of-concept microfluidic device are promising and are a step towards the realization of a photocatalytic artificial lung.<br>by Tania Ullah.<br>S.M.
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Sair, Mark. "Blood flow, peripheral vascular reactivity and tissue oxygenation during systemic sepsis." Thesis, Imperial College London, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.286356.
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Chen, T. "Hyperspectral imaging for the remote sensing of blood oxygenation and emotions." Thesis, Cranfield University, 2012. http://dspace.lib.cranfield.ac.uk/handle/1826/7502.
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This PhD project is a basic research and it concerns with how human’s physiological features, such as tissue oxygen saturation (StO2), can be captured from a stand-off distance and then to understand how this remotely acquired physiological feature can be deployed for biomedical and other applications. This work utilises Hyperspectral Imaging (HSI) within the diffuse optical scattering framework, to assess the StO2 in a contactless remote sensing manner. The assessment involves a detailed investigation about the wavelength dependence of diffuse optical scattering from the skin as well as body tissues, under various forms of optical absorption models. It is concluded that the threechromophore extended Beer Lambert Law model is better suited for assessing the palm and facial tissue oxygenations, especially when spectral data in the wavelengths region of [516-580]nm is used for the analysis. A first attempt of using the facial StO2 to detect and to classify people’s emotional state is initiated in this project. The objective of this work is to understand how strong emotions, such as distress that caused by mental or physical stimulations, can be detected using physiological feature such as StO2. Based on data collected from ~20 participants, it is found that the forehead StO2 is elevated upon the onset of strong emotions that triggered by mental stimulation. The StO2 pattern in the facial region upon strong emotions that are initiated by physical stimulations is quite complicated, and further work is needed for a better understanding of the interplays between bodily physique, individual’s health condition and blood transfusion control mechanism. Most of this work has already been published and future research to follow up when the author returns back to China is highlighted.
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Beckley, Philip D. "Gas exchange during apneic oxygenation with extracorporeal carbon dioxide removal /." The Ohio State University, 1986. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487265555440255.
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Campbell, Elaine Heather. "A comparative study of the modulation of K'+ transport in equine and sheep red blood cells." Thesis, University of Liverpool, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.366508.
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Bannerjee, Jayanta. "Gut and cerebral perfusion and oxygenation in preterm infants receiving blood transfusion." Thesis, Queen Mary, University of London, 2017. http://qmro.qmul.ac.uk/xmlui/handle/123456789/24552.
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Background and Aim: Preterm infants frequently receive blood transfusion (BT) during their stay in the neonatal unit. The aim of this study was to measure the effect of BT on cerebral and gut blood flow and oxygenation in preterm infants in relation to postnatal age. Another aim of the study was also to investigate the influence of measured pre-transfusion RCV on gut perfusion in preterm infants receiving first blood transfusion for clinical indication using NIRS and Doppler ultrasound scan. Methods: Preterm infants admitted to neonatal unit were recruited to three postnatal age groups: 1 to 7 days (group 1; n=20), 8 to 28 days (group 2; n=21) & ≥29 days of life (group 3; n=18). Pre and post-BT Anterior Cerebral artery (ACA) Time Averaged Mean Velocity (TAMV) and Superior Vena Cava (SVC) flow were measured to assess cerebral blood flow. Pre and post-BT Superior mesenteric artery (SMA) peak systolic velocity was measured to assess gut or splanchnic blood flow. Cerebral and gut Tissue Haemoglobin Index (THI), Oxygenation Index (TOI) were measured from 15-20 minutes before to 15-20 minutes post-BT using NIRS. Cerebral and gut fractional tissue oxygen extraction (FTOE) was calculated from the TOI and saturation of oxygen (SaO2). Vital parameters and blood pressure (BP) were also measured continuously from overhead monitors. Pretransfusion red cell volume (RCV) was measured by fetal haemoglobin (HbF) dilution method and compared with the cerebral and gut perfusion and oxygenation changes following blood transfusion. The cerebral and gut perfusion and oxygenation were also measured over a three hour period in 12 control infants not receiving blood transfusion. Results: There were 71 infants included in the study; of them 59 were study infants receiving blood transfusion and 12 were control infants. Amongst the vital parameters, mean BP increased significantly, and there was no significant change in heart rate (HR), respiratory rate (RR) or SaO2 following BT. Pre-transfusion ACA TAMV was higher in Group 2 and 3 compared to Group 1 (p < 0.001) which remained significant after multivariate analysis (p < 0.05). Pretransfusion ACA TAMV decreased significantly (p≤0.04) in all 3 postnatal age groups; pre-transfusion SVC flow decreased significantly in Group 1 (p=0.03) and Group 3 (p < 0.001) following transfusion. Pre-transfusion cTOI was significantly lower in Group 3 compared to Group 1 (p=0.02) which remained significant after multivariate analysis (p < 0.011). The cTHI (p < 0.001) and cTOI (p < 0.05) increased significantly post-transfusion in all three postnatal age groups. PDA had no effect on these measurements. Pre-transfusion SMA PSV increased with postnatal age (group 3 vs. group 1: p < 0.01; CI 0.6 to 0.1), proportion of feeds (> 50% feeds: 0.91±0.4 vs. < 50% feeds: 0.71±0.4 m/sec, p < 0.01); and decreased with presence of PDA (closed PDA: 0.94±0.4 vs. open PDA: 0.68±0.3 m/sec, p=0.006, CI 0.07 to 0.45); but remained unaltered following transfusion. The pre-transfusion sTOI varied with postnatal age (Group 2:44.6 vs. Group1: 36.7%; p=0.03, CI -0.6 to -15.2) on univariate analysis but was not significantly different on multivariate analysis; pre-transfusion sTOI was not influenced by feeds or presence of PDA. The sTHI and sTOI increased (p < 0.01) and sFTOE decreased (p < 0.01) significantly following transfusion in all postnatal age groups.
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Williams, Derrick. "Effect of red blood cell velocity on oxygenation measurements using resonance raman spectroscopy /." VCU Scholars Compass, 2005. http://hdl.handle.net/10156/1445.
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Edyvean, John H. "Factors influencing ventilation, gas exchange and arterial blood oxygenation during exercise in man." Thesis, University of Canterbury. Zoology, 1988. http://hdl.handle.net/10092/6069.
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Factors Influencing Ventilation, Gas Exchange and Arterial Blood Oxygenation During Exercise in Man.
1. At rest and during sub anaerobic steady-state exercise, alveolar and arterial carbon dioxide and oxygen partial pressures are maintained relatively constant by a ventilation which is proportional to both carbon dioxide output and oxygen uptake. Hypoxemia occurs in highly trained athletes at high work intensities. The magnitude of the fall in arterial oxygen tension is related to the degree of relative hypoventilation. Hypoxemia has also been observed following the onset of exercise. To test whether this is similarly related to the degree of hypoventilation 12 normal subjects performed a series of runs, of varying duration, at near maximal intensity, on an electrically driven treadmill. Ventilation and gas exchange variables were computed on a breath-by-breath basis. Arterial blood samples were drawn from the radial artery at regular intervals. Ventilation, oxygen uptake and carbon dioxide output all exhibited a typical three phase response. The kinetics of oxygen uptake were significantly faster than that of carbon dioxide output. The kinetics of ventilation and carbon dioxide output were virtually identical. Occurring simultaneously with the onset of phase II was a fall in ventilator equivalent, end tidal oxygen partial pressure and arterial oxygen tension. In the first 2 minutes of exercise, there were significant correlations between these 3 variables. As exercise continued, arterial oxygen tension
remained depressed while ventilatory equivalent and end tidal oxygen partial pressure returned to resting levels. This data suggests that larger gas stores for carbon dioxide than oxygen causes a kinetic disparity between oxygen uptake and carbon dioxide output following the onset of exercise. As ventilation is proportional to carbon dioxide output hypoventilation occurs with respect to oxygen uptake. This causes a fall in end oxygen of end tidal oxygen partial tension. However, as exercise continues, an increasing dissociation of end tidal oxygen partial pressure and arterial oxygen tension occurs. This further suggests that factors other than hypoventilation also contribute to hypoxemia following the onset of exercise.
2. The degree of hypoventilation and hypoxemia occurring following the onset of exercise exhibits considerable individual variability. The extent to which this is related to the mode of exercise and the frequency of limb movement was studied in 12 normal subjects. Six cyclists each performed an incremental test to maximum on a bicycle ergometer and a series of 2 minute constant load trials using 4 different combinations of load and pedal frequency. Six runners each performed an incremental test to maximum on an electrically driven treadmill and a series of 2 minute constant load trials using 2 different combinations of grade and stride frequency. In all of the incremental tests, ventilation and gas exchange variables were determined from mixed expired samples collected during the last 30 seconds of each 3 minute increment. In all of the 2 minute constant load trials ventilation and gas exchange variables were computed on a breath-by-breath basis. The relationships of ventilation to oxygen uptake and ventilation to carbon dioxide output were constant and independent of pedal frequency during cycling in both the non steady-state and steady-state. However, these relationships were significantly different when both cycling and running on a grade were compared with running on the flat. This was true in both the non steady-state and the steady-state. While running on the flat there was slight hyperventilation with respect to both oxygen uptake and carbon dioxide output, with a slight increase in end tidal oxygen and a slight fall in end tidal carbon dioxide partial pressure. While cycling and running on a grade there was a marked hypoventilation with respect to both oxygen uptake and carbon dioxide output with a large increase in end tidal carbon dioxide and a large fall in end tidal oxygen partial pressure. Entrainment of breathing frequency to movement frequency occurred for varying amounts of time in all subjects. Entrainment interfered with the normal breathing frequency. During running on the flat, a ventilation appropriate to the carbon dioxide output was achieved by compensatory changes in tidal volume. During running up steep grades and cycling with high loads, ventilation was compromised by entrainment of breathing to a lower than normal movement frequency, at a time when tidal volume had attained maximal exercise values. This caused significantly lower than normal ventilatory equivalents for oxygen and carbon dioxide, significant increases in end tidal carbon dioxide partial pressure and significant falls in end tidal oxygen partial pressure. This data suggests that the entrainment of breathing frequency to slow movement frequencies, in certain exercise modes, can cause hypoventilation and a fall in end tidal oxygen partial pressure. It is hypothesised that this in turn will be reflected in the arterial oxygen tension.
3. Sensitivity to carbon dioxide at rest correlates with steady state exercise ventilation. Exercise ventilation increases in proportion to carbon dioxide output in both the non steady-state and the steady-state. It is therefore likely that sensitivity to carbon dioxide at rest will also correlate with exercise ventilation in the non steady-state. The relationship between the resting hypercapnic response and ventilation was studied in 12 normal subjects while running and cycling at near maximal
intensities. Sensitivity to carbon dioxide, expressed as the increase in ventilation per Torr increase in end tidal carbon dioxide partial was determined in all subjects at rest by rebreathing a gas pressure, mixture containing 5% carbon dioxide and 40% oxygen. To facilitate comparisons between individuals of different size, the relationship was expressed per 2 body surface area. Ventilation and gas exchange variables were computed on a breath-by-breath basis. Ventilation was expressed per litre output of carbon dioxide. Occlusion pressure was also measured at regular intervals throughout the 2 minute trial and the relationship to ventilation examined. There were significant correIations between exercise ventilation and the resting hypercapnic response throughout nearly all of the 2 minute trials.
No significant correlations were found between occlusion pressure and exercise ventilation. This data suggests that the individual variability in ventilation and the fall in end tidal oxygen partial pressure following the onset of exercise can, to some extent, be predicted from the resting hypercapnic response.
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Kirchner, Thomas [Verfasser], and Peter [Akademischer Betreuer] Bachert. "Real-time blood oxygenation tomography with multispectral photoacoustics / Thomas Kirchner ; Betreuer: Peter Bachert." Heidelberg : Universitätsbibliothek Heidelberg, 2019. http://d-nb.info/1192373030/34.
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Kuliga, Katarzyna Zofia. "Simultaneous, non-invasive measurements of skin blood flow and oxygenation in healthy humans." Thesis, University of Southampton, 2016. https://eprints.soton.ac.uk/416807/.
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Adequate blood flow within microcirculation and sufficient tissue oxygenation are essential for tissue health. However, the quantitative understanding of dynamics between the microvascular blood flow and oxygenation remains limited. The aim of this study was to explore and interpret simultaneous measurements of skin blood flux (BF) and oxygenation parameters (OXY) recorded from healthy skin. Measurements were recorded using a recently developed (Moor Instruments Ltd, UK) combined Laser Doppler Flowmetry (LDF) and White Light Spectroscopy (WLS) technique, which offer an easy to perform assessment of skin microcirculation and skin oxygenation. In this thesis, two open studies have been conducted in cohorts of healthy volunteers to evaluate combined LDF-WLS measurements and to study the relationship between skin BF and OXY. The engineering challenge of this thesis was to apply signal processing methods to analyse BF and OXY parameters and to extract information that reflect the physiological characteristics of the tissue. Signal processing methods such filtering, convolution, Fourier transform and others served as tools to identify different properties of the signals and subsequently describe the biological systems. The measurements acquired across wide range of values led to mathematical description of the relationship between skin BF and oxygenation and revealed different oscillatory characteristics in BF and OXY signals. The analysis showed resting BF and OXY signals have the highest coherence across low frequency bands. Furthermore, OXY signals are delayed in respect to BF signals. Signal obtained during thermally induced vasodilation showed a shift in signal power to the cardiac frequency band. In conclusion, simultaneous measurements of skin BF and OXY signals in combination with signal processing techniques offer an extended assessment of microvascular function, which may complement clinical assessment of tissue status. Further work is now required to combine presented in this thesis BF and OXY characteristics with other available analysis into clinically useful assessment.
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Kruse, Nicholas T. "Blood Flow and Oxygenation Dynamics as a Result of Human Skeletal Muscle Stretching." University of Toledo / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1430471839.
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Ferreira, Leonardo Franklin. "Dynamics of muscle blood flow, O[subscript2] uptake and muscle microvascular oxygenation during exercise." Diss., Manhattan, Kan. : Kansas State University, 2006. http://hdl.handle.net/2097/201.
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Hadjistassou, Constantine K. "On the physiology of the blood oxygenation level dependent fMRI effect : a computational study." Thesis, University of Oxford, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.670026.
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Kowalsky, Jennifer M. "Variation in Cerebral Oxygenation during Whole Blood Donation: The Impact of Applied Muscle Tension." Ohio University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1306864597.
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Gurley, Katelyn. "USE OF HYBRID DIFFUSE OPTICAL SPECTROSCOPIES IN CONTINUOUS MONITORING OF BLOOD FLOW, BLOOD OXYGENATION, AND OXYGEN CONSUMPTION RATE IN EXERCISING SKELETAL MUSCLE." UKnowledge, 2012. http://uknowledge.uky.edu/cbme_etds/3.
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This study combines noninvasive hybrid diffuse optical spectroscopies [near-infrared spectroscopy (NIRS) and diffuse correlation spectroscopy (DCS)] with occlusive calibration for continuous measurement of absolute blood flow (BF), tissue blood oxygenation (StO2), and oxygen consumption rate (VO2) in exercising skeletal muscle. Subjects performed rhythmic dynamic handgrip exercise, while an optical probe connected to a hybrid NIRS/DCS flow-oximeter directly monitored oxy-, deoxy-, and total hemoglobin concentrations ([HbO2], [Hb], and [tHb]), StO2, relative BF (rBF), and relative VO2 (rVO2) in the forearm flexor muscles. Absolute baseline BF and VO2 were obtained through venous and arterial occlusions, respectively, and used to calibrate continuous relative parameters. Previously known problems with muscle fiber motion artifact in optical measurements were mitigated with a novel dynamometer-based gating algorithm. Nine healthy young subjects were measured and results validated against previous literature findings. Ten older subjects with fibromyalgia and thirteen age-matched healthy controls were then successfully measured to observe differences in hemodynamic and metabolic response to exercise. This study demonstrates a novel application of NIRS/DCS technology to simultaneously evaluate quantitative hemodynamic and metabolic parameters in exercising skeletal muscle. This method has broad application to research and clinical assessment of disease (e.g. peripheral vascular disease, fibromyalgia), treatment evaluation, and sports medicine.
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Craig, Jesse Charles. "Effect of beetroot supplementation on conduit artery blood flow and muscle oxygenation during handgrip exercise." Thesis, Kansas State University, 2015. http://hdl.handle.net/2097/19093.
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Master of Science<br>Department of Kinesiology<br>Thomas J. Barstow<br>Dietary nitrate supplementation via beetroot juice (BR) has been shown to have positive effects on mitochondrial and muscle efficiency during large muscle mass exercise in humans, and more recently on locomotory muscle blood flow [Q-dot] in rats. To date, an integrated measure of these effects has not been performed in humans. Therefore, we assessed the influence of BR on [Q-dot] and muscle oxygenation characteristics during moderate and severe intensity handgrip exercise. Seven healthy men (age: 25 ± 3 yrs; height: 179 ± 4 cm; weight: 82 ± 9 kg) completed four constant-power exercise tests randomly assigned to condition (BR or placebo (PL)) and intensity (moderate (40% peak) or severe (85% peak)). Resting mean arterial pressure was significantly lower after BR compared to PL (79.3 ± 5.8 vs 86.8 ± 6.7 mmHg; p < 0.01). All subjects were able to sustain 10 min of exercise at moderate intensity in both conditions. BR had no significant effect on exercise tolerance during severe (342 ± 83 vs 382 ± 138 s, p = 0.382). Brachial artery [Q-dot] was not significantly different after BR at rest or any time during exercise in either intensity. Deoxygenated-[hemoglobin + myoglobin] was elevated at min 2 & 3 for moderate (p < 0.05) and throughout severe exercise (p = 0.03) after BR. The estimated metabolic cost ([V-dot]O₂) was not significantly different during either intensity after BR. These findings support the notion that an acute dose of BR may be valuable to reduce blood pressure in young adults, but revealed that it does not augment [Q-dot] or [V-dot]O₂ during small muscle mass handgrip exercise.
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Olsson, Richard. "The Microvasculature of Endogenous and Transplanted Pancreatic Islets : Blood Perfusion, Oxygenation and Islet Endocrine Function." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-7107.
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Herspring, Kyle F. "Effects of antioxidants on contracting spinotrapezius muscle microvascular oxygenation and blood flow in aged rats." Thesis, Manhattan, Kan. : Kansas State University, 2008. http://hdl.handle.net/2097/700.
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Jöbsis, Paul D. "Muscle oxygenation and blood flow during submersion in ducks (anas platyrhynchos) and seals (phoca vitulina) /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 1998. http://wwwlib.umi.com/cr/ucsd/fullcit?p9907822.
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Sortica, da Costa Cristine. "Monitoring of cerebral oxygenation, cerebrovascular reactivity and circulatory function in preterm infants." Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/283240.
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Monitoring of cerebral oxygenation, cerebrovascular reactivity and circulatory function in preterm infants Brain injury in the preterm infant is associated with death and lifelong disability. Cerebral hypoxia and fluctuations in cerebral blood flow in the first two days of life have been implicated in the pathophysiology of haemorrhagic and ischaemic brain injury. Monitoring of haemodynamic changes during the early transitional circulation from in-utero to ex-utero life are currently based on standard measurements of systemic oxygenation and mean arterial blood pressure, with no reliable assessment of end-organ perfusion. In this thesis, measurements using near-infrared spectroscopy (NIRS) and functional echocardiography were made to assess cerebral perfusion and systemic blood flow in a cohort of preterm infants undergoing intensive care. This thesis is divided into four sections: i) The feasibility of continuous monitoring of cerebral oxygenation and cerebrovascular reactivity is demonstrated in a series of case reviews, and the association between cerebral oxygenation and cerebrovascular reactivity with outcome of brain injury and mortality is described. ii) Combining measurements of systemic blood flow with end organ perfusion was applied to define MABPOPT in preterm infants based on an index of cerebrovascular reactivity. Deviations below MABPOPT were associated with intraventricular haemorrhage and mortality. iii) The complexity of brain and systemic signals was studied by using multi-scale entropy analysis. Most studies using cerebral NIRS or systemic measurements of blood flow use linear analysis; however, a complex biological system, such as the human brain, includes many regulatory mechanisms that interact in a complex manner, resulting in effects that cannot be understood wholly through the analysis of its individual constituents. Lower complexity of brain signals was observed in infants who developed intraventricular hemorrhage or died. iv) Changes in systemic and cerebral oxygenation in a cohort of preterm infants in the first 48 hours of life was assessed using functional echocardiography. The patterns of changes in cardiac output and cerebral oxygenation in infants who did and did not have intraventricular haemorrhage are discussed. Furthermore, the relationship between the presence of a haemodynamically significant ductus arteriosus and brain injury is assessed.
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Belcher, Donald Andrew. "Oxygenation of Solid Tumor Tissue Facilitated by Polymerized Human Hemoglobins." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu156294520544597.
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Schmutzler, Luis Melchert Faber. "Avaliação de oxigenadores de sangue utilizando principios de transferencia de massa e tecnica de perda de carga." [s.n.], 2004. http://repositorio.unicamp.br/jspui/handle/REPOSIP/262942.
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Orientadores: Antonio Celso Fonseca de Arruda e Waldyr Parolari Novello<br>Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica<br>Made available in DSpace on 2018-08-04T02:53:24Z (GMT). No. of bitstreams: 1
Schmutzler_LuisMelchertFaber_D.pdf: 18427607 bytes, checksum: a256aa1b714dbaf8eeb63daf6be84dd1 (MD5)
Previous issue date: 2004<br>Resumo: Oxigenadores de sangue tipo de membrana são construídos para trocarem gases de respiração através de uma área de contato, a sua chamada área de troca. Devido a características do processo de fabricação, esta área pode softer variações. Neste trabalho procurou-se desenvolver métodos de avaliação da variação desta área, por meio da medição da transferência de massa e da perda de carga. A técnica utilizando transferência de massa gerou dois métodos de avaliação, um utilizando como fase líquida a água destilada e o outro, uma emulsão de perfluorcarbono. No intuito de assegurar a funcionalidade da emulsão disponível e assim a precisão do trabalho, foi desenvolvido um método de validação para se avaliar a capacidade de dissolver Oxigênio da mesma. O outro método para avaliação da área de troca é baseado naperda de carga, sofrida por um fluxo de gás ao percorrer o circuito de membranas do oxigenador sob teste. Todos os métodos apresentaram resultados suficientemente satisfatórios, permitindo estabelecer diferenças de desempenho entre as unidades testadas e a validação da área de troca, por comparação com um padrão sendo que, os métodos de transferência de massa com água e o da perda de carga com gás são métodos não destrutivos. Os resultados obtidos utilizando-se o método com gás forneceram uma melhor resolução<br>Abstract: Membrane blood oxygenators are built to exchange perspiration gases thru an exchange area, but due to the fabrication process characteristics, this exchange area may vary. In this work, exchange area evaluation methods were developed using mass transfer and head loss techniques. The mass transfer technique generated two methods, one using distilled water and other using perfluorocarbon emulsion. Envisaging assurance on the functionality of the perfluorocarbon emulsion and by the way, the quality of the work, a method for evaluating the Oxygen solving capability was also developed. The other area evaluation method is based on a gas flow head loss while passing thru the membrane inside of the under testing device. Ali methods presented satisfactory results, allowing establishing performance differences among tested units and the area validation by comparing to a standard device. The mass transfer water based and the gas flow head loss are non destructive methods. The results provided by the gas flow head loss method achieved a better level of resolution<br>Doutorado<br>Materiais e Processos de Fabricação<br>Doutor em Engenharia Mecânica
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Lauver, Jakob Del. "The Effect of Eccentric Exercise with Blood Flow Restriction on Muscle Damage, Neuromuscular Activation, and Microvascular Oxygenation." University of Toledo / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1430489158.
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Ahmadi, Sirous. "Monitoring muscle oxygenation and myoelectric activity after damage-inducing exercise." Thesis, The University of Sydney, 2007. http://hdl.handle.net/2123/2240.
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In this thesis, three experiments were conducted to monitor: (i) muscle oxygenation and electromyographic activity of the biceps brachii after exercise-induced muscle damage (ii) muscle oxygenation after downhill walking-induced muscle damage, and, (iii) muscle oxygenation following a bout of vigorous concentric exercise. Maximal eccentric exercise (EE) of biceps brachii resulted in significantly increased mean resting oxygen saturation and decreased deoxyhaemoglobin. During isometric contractions at 50% and 80% of subjects’ maximum voluntary torque (MVT), oxygen desaturation and resaturation kinetics and volume were significantly decreased after EE, and these declines were significantly prevalent over the following 6 days. Additionally, a significant shift in median frequency intercept (measured by electromyography; EMG) towards lower frequencies was observed during isometric contractions at both 50% and 80% MVT after EE in the exercised arm. After an exhaustive session of downhill walking, another form of EE, resting total haemoglobin and oxyhaemoglobin decreased. Furthermore, during isometric contractions at 30%, 50% and 80% of MVT, prolonged and significant increases were observed in oxygen desaturation and resaturation kinetics and volumes after ambulatory EE. In contrast to the two EE experiments, concentric contractions did not evoke any prolonged changes in muscle oxygenation. Collectively, the findings of this thesis revealed significant and prolonged changes in muscle oxygenation at rest and during exercise, following sessions of strenuous eccentric exercise. Although not clear, the possible mechanism responsible for the changes in muscle oxygenation after EE could be increased resting muscle oxygen utilization due to probable muscle damage and a subsequent requirement of energy demanding repair processes. Concentric exercise resulted in fatigue, but it did not affect muscle oxygenation. Although a prolonged reduction in EMG median frequency intercept was observed after EE, this was not closely time-associated with the biochemical, anthropometric or functional markers of muscle damage.
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Ahmadi, Sirous. "Monitoring muscle oxygenation and myoelectric activity after damage-inducing exercise." University of Sydney, 2007. http://hdl.handle.net/2123/2240.
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Doctor of Philosophy<br>In this thesis, three experiments were conducted to monitor: (i) muscle oxygenation and electromyographic activity of the biceps brachii after exercise-induced muscle damage (ii) muscle oxygenation after downhill walking-induced muscle damage, and, (iii) muscle oxygenation following a bout of vigorous concentric exercise. Maximal eccentric exercise (EE) of biceps brachii resulted in significantly increased mean resting oxygen saturation and decreased deoxyhaemoglobin. During isometric contractions at 50% and 80% of subjects’ maximum voluntary torque (MVT), oxygen desaturation and resaturation kinetics and volume were significantly decreased after EE, and these declines were significantly prevalent over the following 6 days. Additionally, a significant shift in median frequency intercept (measured by electromyography; EMG) towards lower frequencies was observed during isometric contractions at both 50% and 80% MVT after EE in the exercised arm. After an exhaustive session of downhill walking, another form of EE, resting total haemoglobin and oxyhaemoglobin decreased. Furthermore, during isometric contractions at 30%, 50% and 80% of MVT, prolonged and significant increases were observed in oxygen desaturation and resaturation kinetics and volumes after ambulatory EE. In contrast to the two EE experiments, concentric contractions did not evoke any prolonged changes in muscle oxygenation. Collectively, the findings of this thesis revealed significant and prolonged changes in muscle oxygenation at rest and during exercise, following sessions of strenuous eccentric exercise. Although not clear, the possible mechanism responsible for the changes in muscle oxygenation after EE could be increased resting muscle oxygen utilization due to probable muscle damage and a subsequent requirement of energy demanding repair processes. Concentric exercise resulted in fatigue, but it did not affect muscle oxygenation. Although a prolonged reduction in EMG median frequency intercept was observed after EE, this was not closely time-associated with the biochemical, anthropometric or functional markers of muscle damage.
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Atanya, Monica. "The Effects of Acid-Base Parameters, Oxygen and Heparin on the Ability to Detect Changes in the Blood Status of End-Stage Renal Disease Patients Undergoing Hemodialysis Using Whole Blood-Based Optical Spectroscopy." Thèse, Université d'Ottawa / University of Ottawa, 2011. http://hdl.handle.net/10393/19875.
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Relative changes are detectable in the blood of end-stage renal disease (ESRD) patients during hemodialysis (HD) treatment using optical spectroscopy. However, the potential impacts of several confounding factors that could affect the detection of these changes have not been evaluated. The objectives of this thesis were to: 1) investigate how the variations and/or changes in acid-base and oxygen parameters during HD treatment can affect the optical signature of whole blood of ESRD patients, 2) to investigate the effect of heparin on the optical properties of whole blood and its impact on our method.
Blood samples were drawn from 23 ESRD patients at 5 time points during a 4 hour HD treatment and sent for blood gas and blood spectroscopy analyses. No significant correlations were found between the changes in the blood transmittance spectra and acid-base and oxygen parameters. This indicates that the perturbations in these parameters due to HD procedures do not confound the detection of changes in the blood transmittance spectra of ESRD patients during HD treatment. Additionally, the effect of heparin in modifying the optical properties of whole blood does not confound the detection of changes in the blood of ESRD patients due to HD treatment using whole blood-based optical spectroscopy.
ANOVA revealed significant (P<0.05) measurable changes in the blood transmittance spectra of ESRD patients during HD treatment. Significant spectral differences (P<0.05) were found between ESRD patients. The lack of uniform spectral characteristics across patients is
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Svenmarker, Staffan. "Heparin coating and cardiotomy suction in cardiopulmonary bypass." Doctoral thesis, Umeå : Univ, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-134.
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Dodhy, Sami. "EFFECTS OF ISCHEMIA AND REPERFUSION ON THE LOCAL REGULATION OF OXYGEN CONSUMPTION, TISSUE OXYGENATION AND BLOOD SUPPLY IN RAT SKELETAL MUSCLE." VCU Scholars Compass, 2013. http://scholarscompass.vcu.edu/etd/3250.
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In resting muscle, blood flow is regulated to meet the demand for O2 by the tissue. A modified ischemia (I)/reperfusion(R) investigation was systematically run and PISFO2, PaO2, Q and VO2 were observed. Twenty-nine spinotrapezius muscles from male Sprague-Dawley rats (284±20 grams) were surgically exteriorized for intravital microscopy to test a model relating blood flow, O2 supply and O2 demand. The model can aid in the understanding of the regulation of tissue PO2. The interstitial PO2 (PISFO2) and perivascular PO2 (PaO2) measurements were made using phosphorescence quenching microscopy (PQM). O2 consumption (VO2) values were obtained with a quasi-continuous, flash-synchronized, pressurized airbag to initiate ischemia and sample the rate of O¬2 change (dPO2/dt). Centerline red blood cell velocity was measured with an Optical Doppler Velocimeter and converted to flow using vessel diameter. 5-, 15-, 30-, 60-, 300- and 600-second ischemic durations were used to observe changes in PISFO2, Q, and VO2. A critical point was observed following 30 seconds of (I) where dPISFO2/dt during recovery was the fastest (4.25±0.72 mmHg/s) and was 1.00±0.16 mmHg/s following 600 seconds. Flow recovery, dQ/dt, peaked to 3.88±0.64 (µl•min-1)/s after 60 seconds of (I) but significantly dropped to 2.83±0.55 (µl•min-1)/s following 300 seconds of (I) but increased to 2.92±0.45 (µl•min-1)/s following 600 seconds. This gives evidence to a no-reflow phenomenon occurring in the extended periods of ischemia. A peak in VO¬2 to 309.2±45.0 nl O2/cm3•s with a time course of 160 seconds occurred following 600 seconds of ischemia. As the ischemic duration decreased, the time course and peak VO2 also decreased. VO2 following 300 seconds of (I) was significantly higher than 5-60 seconds of (I) (p <0.05) but was not significantly different from 600 seconds of (I). The information collected during the Q and VO2 studies can be incorporated into a factor, M, that relates VO2, Q and ∆PO2. M calculated for the recovery of 5- through 60-second (I) groups reasonably relates the three variables due to consistency and little variability. However, recovery in 600- and especially 300-second (I) groups showed higher variability in M which requires more consideration.
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Welter, Michael Verfasser], and Heiko [Akademischer Betreuer] [Rieger. "A theoretical model of vascularized tumors : simulation of blood vessel network remodeling, interstitial fluid flow and oxygenation / Michael Welter ; Betreuer: Heiko Rieger." Saarbrücken : Saarländische Universitäts- und Landesbibliothek, 2017. http://d-nb.info/1123071217/34.
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Welter, Michael [Verfasser], and Heiko [Akademischer Betreuer] Rieger. "A theoretical model of vascularized tumors : simulation of blood vessel network remodeling, interstitial fluid flow and oxygenation / Michael Welter ; Betreuer: Heiko Rieger." Saarbrücken : Saarländische Universitäts- und Landesbibliothek, 2017. http://d-nb.info/1123071217/34.
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Dolet, Aneline. "2D and 3D multispectral photoacoustic imaging - Application to the evaluation of blood oxygen concentration." Thesis, Lyon, 2018. http://www.theses.fr/2018LYSEI070/document.
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L'imagerie photoacoustique est une modalité d'imagerie fonctionnelle basée sur la génération d'ondes acoustiques par des tissus soumis à une illumination optique (impulsion laser). L'utilisation de différentes longueurs d'ondes optiques permet la discrimination des milieux imagés. Cette modalité est prometteuse pour de nombreuses applications médicales liées, par exemple, à la croissance, au vieillissement et à l'évolution de la vascularisation des tissus. En effet, l'accès à l'oxygénation du sang dans les tissus est rendu possible par l'imagerie photoacoustique. Cela permet, entre autres applications, la discrimination de tumeurs bénignes ou malignes et la datation de la mort tissulaire (nécrose). Ce travail de thèse a pour objectif principal la construction d'une chaîne de traitement des données photoacoustiques multispectrales pour le calcul de l'oxygénation du sang dans les tissus. Les principales étapes sont, d'une part, la discrimination des données (clustering), pour extraire les zones d'intérêt, et d'autre part, la quantification des différents constituants présents dans celles-ci (unmixing). Plusieurs méthodes non supervisées de discrimination et de quantification ont été développées et leurs performances comparées sur des données photoacoustiques multispectrales expérimentales. Celles-ci ont été acquises sur la plateforme photoacoustique du laboratoire, lors de collaborations avec d'autres laboratoires et également sur un système commercial. Pour la validation des méthodes développées, de nombreux fantômes contenant différents absorbeurs optiques ont été conçus. Lors du séjour de cotutelle de thèse en Italie, des modes d'imagerie spécifiques pour l'imagerie photoacoustique 2D et 3D temps-réel ont été développés sur un échographe de recherche. Enfin, des acquisitions in vivo sur modèle animal (souris) au moyen d'un système commercial ont été réalisées pour valider ces développements<br>Photoacoustic imaging is a functional technique based on the creation of acoustic waves from tissues excited by an optical source (laser pulses). The illumination of a region of interest, with a range of optical wavelengths, allows the discrimination of the imaged media. This modality is promising for various medical applications in which growth, aging and evolution of tissue vascularization have to be studied. Thereby, photoacoustic imaging provides access to blood oxygenation in biological tissues and also allows the discrimination of benign or malignant tumors and the dating of tissue death (necrosis). The present thesis aims at developing a multispectral photoacoustic image processing chain for the calculation of blood oxygenation in biological tissues. The main steps are, first, the data discrimination (clustering), to extract the regions of interest, and second, the quantification of the different media in these regions (unmixing). Several unsupervised clustering and unmixing methods have been developed and their performance compared on experimental multispectral photoacoustic data. They were acquired on the experimental photoacoustic platform of the laboratory, during collaborations with other laboratories and also on a commercial system. For the validation of the developed methods, many phantoms containing different optical absorbers have been produced. During the co-supervision stay in Italy, specific imaging modes for 2D and 3D real-time photoacoustic imaging were developed on a research scanner. Finally, in vivo acquisitions using a commercial system were conducted on animal model (mouse) to validate these developments
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Pegoraro, Roger V. "The influence of postural change and executive function tasks on cerebral blood supply and cortical oxygenation in older people and people with Parkinson's disease." Thesis, Queensland University of Technology, 2017. https://eprints.qut.edu.au/111054/1/Roger_Pegoraro_Thesis.pdf.
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This thesis investigated cerebral oxygen and blood supply during postural change and cognitive tasks for older people and people with Parkinson's disease. During postural changes cerebral oxygen and blood supply were maintained for both groups irrespective of presence of orthostatic hypotension. Cerebral oxygenation changes were larger in the dorso-lateral pre-frontal cortices compared to the orbito-frontal cortices. During an executive cognitive task people with Parkinson's disease had smaller changes in cortical oxygenation than older people, irrespective of presence of orthostatic hypotension. However, blood supply to the brain was similar for all groups across all postures and tasks. This research provides proof of concept for novel cost-effective clinical assessments of brain function.
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Cope, Mark. "The development of a near infrared spectroscopy system and its application for non-invasive monitoring of cerebral blood and tissue oxygenation in the newborn infants." Thesis, University College London (University of London), 1991. http://discovery.ucl.ac.uk/1317956/.
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This project had two main objectives. The first of these was to design and construct a spectroscopic instrument to monitor small changes in optical transmission across an infant's head at several near infrared wavelengths resulting from changes in the cerebral oxygenation status. The overall attenuation of light by brain tissue is very high and is dominated by the scattering properties of the tissue. Hence a major requirement of the instrument was the ability to measure spectral changes at very low light levels. Once the instrument was available, the second objective was to convert the measured changes in optical transmission into changes in the concentration of the naturally occurring chromophores oxyhaemoglobin, deoxyhaemoglobin and oxidised and reduced cytochrome c oxidase. An important aspect of the work was that the chromophore concentration measurements should be quantified in non-arbitrary units. Medical Physics is, by its nature, highly interdisciplinary and this is reflected in the introductory chapter which briefly covers the clinical problems, the medical science background and the technical aspects of monitoring the cerebral oxygenation status of newborn infants. The second and third chapters examine those constituents of brain tissue which absorb and scatter light and how the complication of multiple scattering can be dealt with in performing quantitative spectroscopy. The fourth and fifth chapters describe the technical details of the instrument design and construction from the initial step of setting its design specifications to the final testing of its performance. The sixth chapter examines the absorption characteristics of the main chromophores of interest namely oxyhaemoglobin, deoxyhaemoglobin and the cytochrome enzymes of the respiratory chain within the brain cells. A discussion on the interpretation of the redox state of the respiratory enzymes in terms of the metabolic state of the brain is also included. The final chapter describes the data analysis methods, the measurement of optical pathlengths in scattering media and introduces a non-linear modification to the Beer-Lambert law which improves the accuracy of the spectroscopic measurements in highly scattering media.
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Glielmi, Christopher B. "Expanding the role of functional mri in rehabilitation research." Diss., Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/33972.
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Functional magnetic resonance imaging (fMRI) based on blood oxygenation level dependent (BOLD) contrast has become a universal methodology in functional neuroimaging. However, the BOLD signal consists of a mix of physiological parameters and has relatively poor reproducibility. As fMRI becomes a prominent research tool for rehabilitation studies involving repeated measures of the human brain, more quantitative and stable fMRI contrasts are needed. This dissertation enhances quantitative measures to complement BOLD fMRI. These additional markers, cerebral blood flow (CBF) and cerebral blood volume (CBV) (and hence cerebral metabolic rate of oxygen (CMRO₂) modeling) are more specific imaging markers of neuronal activity than BOLD. The first aim of this dissertation assesses feasibility of complementing BOLD with quantitative fMRI measures in subjects with central visual impairment. Second, image acquisition and analysis are developed to enhance quantitative fMRI by quantifying CBV while simultaneously acquiring CBF and BOLD images. This aim seeks to relax assumptions related to existing methods that are not suitable for patient populations. Finally, CBF acquisition using a low-cost local labeling coil, which improves image quality, is combined with simultaneous acquisition of two types of traditional BOLD contrast. The demonstrated enhancement of CBF, CBV and CMRO₂measures can lead to better characterization of pathophysiology and treatment effects.
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Bliss, Matthew Vern. "PHYSIOLOGICAL DIFFERENCES BETWEEN FIT AND UNFIT COLLEGE-AGE MALES DURING EXERCISE IN NORMOBARIC HYPOXIA." Kent State University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=kent1382384591.
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Nuttall, Rachel Corinne [Verfasser], Christian [Akademischer Betreuer] Sorg, Afra [Gutachter] Wohlschläger, and Markus [Gutachter] Ploner. "Evoked response variability across alpha oscillatory sources to visual flicker stimulation: An investigation in humans using electrophysiological and blood-oxygenation recordings / Rachel Corinne Nuttall ; Gutachter: Afra Wohlschläger, Markus Ploner ; Betreuer: Christian Sorg." München : Universitätsbibliothek der TU München, 2021. http://d-nb.info/1228073260/34.
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Desanlis, Julien. "Haemodynamic and cardiorespiratory acute and chronic responses to different blood flow restrictions at rest and during exercise." Electronic Thesis or Diss., université Paris-Saclay, 2024. http://www.theses.fr/2024UPASW008.
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L'ischémie induite par un brassard gonflé au repos (Ischemic Preconditioning, IPC) ou à l'effort (Blood Flow Restriction, BFR) affecte les paramètres de la chaîne de transport de l'oxygène, en fonction de la pression appliquée. Cette hypoxie locale est utilisée pour optimiser les effets de l'entraînement. L'objectif de ce travail de thèse est donc d'étudier les réponses et adaptations hémodynamiques et cardio- respiratoires à différents niveaux de restriction du flux sanguin, au repos ou à l'effort. Afin d'étudier les réponses hémodynamiques au repos, la fiabilité des mesures d'oxygénation musculaire obtenues avec de la spectroscopie infrarouge (NIRS) est testée. Les études menées dans ce travail doctoral montrent une excellente fiabilité des mesures intra-session, mais un manque de fiabilité inter-sessions. Au repos, l'oxygénation musculaire est affectée différemment entre une occlusion vasculaire partielle ou complète. Cependant, la réponse n'est pas différente entre une pression suprasystolique absolue et individualisée. A l'effort, quatre semaines d'entraînement aérobie à haute intensité couplé à différents niveaux de BFR améliorent la performance lors de l'épreuve maximale incrémentée et l'efficience à intensité sous-maximale, sans distinction entre les pressions d'occlusion. Ces résultats ouvrent des perspectives de recherche sur les processus physiologiques impliqués dans les réponses à l'hypoxie locale et suggèrent des applications du BFR dans l'entraînement aérobie pour améliorer les paramètres cardiovasculaires et respiratoires<br>Ischaemia induced by an inflated cuff at rest (Ischemic Preconditioning, IPC) or during exercise (Blood Flow Restriction, BFR) affects the oxygen transport chain, depending on the cuff pressure. This local hypoxia is used to optimise training effects. The objective of this thesis is to study the haemodynamic and cardio-respiratory responses and adaptations to different levels of blood flow restriction, at rest or during exercise. The reliability of muscle oxygenation values obtained using near-infrared spectroscopy (NIRS) is studied to enable further investigations of haemodynamic responses. The results show excellent intra-session reliability but a lack of inter-session reliability. At rest, muscle oxygenation is significantly affected by partial and complete occlusions differently. However, no significant differences are observed between absolute and individualised supra-systolic pressures. During exercise, four weeks of high-intensity aerobic training with various BFR levels improve cycling performance in a maximal incremental test and submaximal efficiency, regardless of the training pressure used. The results of the present PhD manuscript provide research perspectives on the physiological processes involved in responses to local hypoxia and suggest applications of BFR in aerobic training to improve cardiovascular and respiratory parameters
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Stephen, Ian D. "Skin colour, pigmentation and the perceived health of human faces." Thesis, St Andrews, 2009. http://hdl.handle.net/10023/753.
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Goenarjo, Roman. "Effect of age, vascular parameters, physical activity, and cardiorespiratory fitness on executive performances : role of cerebral oxygenation." Thesis, Poitiers, 2020. http://www.theses.fr/2020POIT2252.
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De nombreuses études ont montré que l’activité physique régulière et le niveau de condition physique étaient associés à la performance cognitive et plus particulièrement aux fonctions exécutives. Parmi les nombreux mécanismes physiologiques qui sous-tendent cette association, l’oxygénation du cortex préfrontal semble avoir un rôle majeur. Il est bien établi que l'impact spécifique de l'oxygénation préfrontale sur le lien entre l’activité physique et la cognition est influencé par certains facteurs comme le sexe, l’âge, et la santé cardio-vasculaire. Ainsi, l'objectif de cette thèse était d'étudier l'impact de l'activité physique et du niveau de condition physique sur les fonctions exécutives au cours du vieillissement chez des hommes sains. L'influence de l'oxygénation du cortex préfrontal et de la santé cardiovasculaire sur la relation « niveau de condition physique – fonctions exécutives » a également été étudiée. A partir de la littérature existante, nous avons formulé l’hypothèse que l’activité physique et le profil cardiorespiratoire auraient des effets bénéfiques sur les fonctions exécutives chez les hommes jeunes et plus âgés, et que pour ces deux populations, l’oxygénation du cortex préfrontal et la santé cardiovasculaire seraient impliquées dans cette relation. Une revue de littérature et quatre études transversales ont été réalisées pour vérifier ces hypothèses.Notre revue de littérature chez les personnes âgées a indiqué que:• Un niveau de condition physique plus élevé est associé à de meilleures performances dans certains tests de fonction exécutive.• Un niveau de condition physique plus élevé est associé à une moindre rigidité artérielle, à une réactivité vasculaire plus élevée, et à une plus grande amplitude de l'oxygénation cérébrale au cours de l'exercice ou d'une tâche cognitives.• Un plus grand volume de matière grise et une plus grande d’intégrité de la substance blanche sont liés àu profil cardiorespiratoire, mais moins systématiquement associés à l’activité physique.• Au moins de 12 semaines d'un programme d'exercice aérobie sont nécessaires pour obtenir un effet significatif sur les fonctions cognitivesNos études expérimentales nous ont permis de conclure que:Chez les jeunes hommes:• Les individus actifs obtenaient de meilleures performances dans les tâches exécutives que les inactifs et avaient un changement important dans l'oxygénation du cortex préfrontal lors des conditions les plus complexes de la tâche de Stroop.• Un niveau de condition physique plus élevé était liée à une meilleure performance en double tâche et une plus grande oxygénation des deux côtés du cortex préfrontal.Chez les hommes âgés:• Le niveau de condition physique n’est pas lié aux performances de Stroop ni à l’ oxygénation du cortex préfrontal.• Un niveau de condition physique plus élevé est lié à une meilleure performance et une plus grande oxygénation de cortex préfrontal droit au cours d’une tâche de Stroop dans le groupe de 61+ ans mais pas dans le groupe de 55-60 ans, ce qui suggère l'importance de la classification de groupe d'âge pour évaluer l'effet du niveau de condition physique sur les fonctions exécutives chez les hommes âgés.• Les hommes âgés ont des relations plus fortes entre plusieurs paramètres cardiovasculaires et la performance des tâches de Stroop que les jeunes hommesCette projet de recherche montre que l'activité physique et le niveau de condition physique ont des effets positifs sur les fonctions exécutives chez les jeunes hommes et âgés, en particulier dans la tâche la plus complexes. L’oxygénation du cortex préfrontal et la santé cardiovasculaire modulent la relation entre l'activité physique et la cognition. Nous concluons que d’être physiquement actif ou d'avoir un meilleur niveau de condition physique donne des effets avantageux pour la santé vasculaire, l’oxygénation du cortex préfrontal, et les fonctions exécutives non seulement chez les hommes âgés, mais aussi chez les jeunes hommes<br>Many studies have reported that regular physical activity and cardiorespiratory fitness were associated with cognitive performance and more selectively with executive functions. Among numerous physiological mechanisms that may underlie the association between them, prefrontal cortex oxygenation seems to play a major role. However, the specific impact of prefrontal oxygenation on the link between physical activity and cognition is influenced by several factors, such as gender, age, or cardiovascular health. Therefore, the aim of this thesis was to investigate the impact of physical activity and cardiorespiratory fitness on executive functions across the adults' age span in healthy males, as well as the influence of prefrontal cortex oxygenation and cardiovascular health. To obtain those objectives, we conducted a review of the effect of physical activity on the brain in older adults and four cross-sectional studies. From our review, we highlighted that: • In older adults, higher fitness level is associated with better performance in several executive function tests. Even though the limited number of studies available makes it difficult to draw definitive conclusions.• Better cardiovascular fitness in older adults is associated with improve arterial stiffness, higher vascular reactivity, and greater amplitude of cerebral oxygenation during exercise or cognitive tasks.• Greater gray matter volume and white matter integrity were related to the cardiorespiratory fitness but less consistently related to physical activity.• At least 12 weeks of an aerobic exercise program are required to give advantageous effects to the brainAnd our experimental works show that:In young males:• The active individuals performed better in executive tasks than their inactive counterparts and had a larger change in prefrontal cortex oxygenation during the most complex conditions of Stroop task.• High cardiorespiratory fitness was related to a better performance in dual-task and greater oxygenation on both sides of the prefrontal cortex.In older males:• Cardiorespiratory fitness is not related to Stroop task performance nor prefrontal cortex oxygenation in overall older males.• Higher cardiorespiratory fitness was related to a better performance and greater right prefrontal cortex oxygenation during a Stroop task in 61+ years old group but not in 55-60 years old group, suggesting the importance of age-group classification to evaluate the effect of cardiorespiratory fitness on executive function in older male subjects.• Older males have stronger relationships between several vascular parameters and Stroop task performance than young malesThis work shows the relationship between physical activity and cardiorespiratory fitness on executive functions in young and older males. The potential neurophysiological mechanisms that underlie that relationship, especially prefrontal oxygenation and vascular health, are presented
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Biazon, Thaís Marina Pires de Campos. "Efeito da hipóxia local na magnitude da ativação, força, massa e arquitetura muscular decorrente do treinamento de força." Universidade Federal de São Carlos, 2016. https://repositorio.ufscar.br/handle/ufscar/8018.
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Previous issue date: 2016-04-28<br>Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)<br>Local hypoxia (i.e. intramuscular) resulting from resistance training (RT) contributes to ions H+ accumulation and decreased muscle pH (i.e. metabolic stress). It has been
suggested that the accumulation of these metabolites promotes an increase in the motor
units (MU) recruitment and consequent increase in cross-sectional area (CSA) and
muscle strength. Nevertheless, it remain sunknown whether the level of local hypoxia
can affect the magnitude of these adaptations. Objective: The objective of the study
was to analyze and compare the effect of local hypoxia during low-intensity resistance
training with blood flow restriction (LI-BFR: 3-4 x 20/20% of one repetition maximum
[1-RM] / 60% total pressure of occlusion), high-intensity resistance training (HI-RT: 3-4 x 10/80% of 1RM) and high-intensity resistance training with blood flow restriction
(HI-BFR: 3-4 x 10/80% 1-RM / 60% total occlusion pressure) on muscle activation,
strength, mass and architecture in young individuals. Methods: Thirty young men were
selected and each leg allocated to three experimental conditions through unilateral knee extension in randomized order and counterbalanced after ranking by strength level (1- RM) and vastus lateralis (VL) muscle CSA quartiles. The dynamic maximum force was measured by 1-RM test and CSA acquisition, muscle thickness (MT), pennation angle (PA) and VL fascicle length (FL) was performed through ultrasound images. The training program consisted of 10 weeks with a minimum interval of 72 hours between training sessions and the measurement of muscle activation by surface electromyography (EMG) and deoxyhemoglobin ([HHb]) and oxyhemoglobin ([HbO2]) concentrations through near-infrared espectroscopy (NIRS) of VL, performed during the training session with relative load obtained after the 1-RM, before (T1), after five (T2) and ten weeks (T3) training. Results: The training total volume (TV) was greater for HI-RT and HI-BFR compared to LI-BFR. There was no difference between the groups in regarding the increase of 1-RM, CSA, MT and AP. However, the FL showed higher increase for HI-BFR compared to HI-RT and LI-BFR. Regarding the magnitude of the EMG, the HI-BFR group showed higher values than HI-RT and LI-BFR. On the other hand, [HHb] were higher for HI-BFR and LI-BFR, however there was no difference between groups on the reduction of [HbO2].Conclusion: The level of local hypoxia does not influence the magnitude of the increase of muscle activation, strength, mass and architecture changes after resistance training. However, the addition of local hypoxia seems to have a greater contribution to the adjustments resulting from the low-intensity resistance training compared to high intensity.<br>A hipóxia local (i.e. intramuscular) decorrente do treinamento força (TF) contribui para
o acúmulo de íons H+ e diminuição do pH muscular (i.e. estresse metabólico). Sugere-se
que o acúmulo desses metabólitos promove aumento no recrutamento de unidades
motoras (UM) e consequente aumento da área de secção transversa (AST) e força
muscular. Embora isso seja sugerido, ainda não se sabe se o nível de hipóxia local pode
afetar a magnitude dessas adaptações. Objetivo: O objetivo do estudo foi analisar e comparar o efeito da hipóxia local durante o treinamento de força de baixa intensidade com restrição do fluxo sanguíneo (TFBI-RFS: 3-4 x 20 / 20% de uma repetição máxima [1-RM] / 60% pressão total de oclusão), treinamento de força de alta intensidade (TFAI: 3-4 x 10 / 80% de 1-RM) e treinamento de força de alta intensidade com restrição do fluxo sanguíneo (TFAI-RFS: 3-4 x 10 / 80% de 1-RM/ 60% pressão total de oclusão) na ativação, força, massa e arquitetura muscular em indivíduos jovens. Métodos: Trinta homens jovens foram selecionados e cada membro inferior alocado nas três condições experimentais de TF de extensão unilateral de joelho em ordem aleatorizada e contrabalanceada após ranqueamento em quartis, para nível de força (1-RM) e AST muscular do músculo vasto lateral (VL). A força máxima dinâmica foi mensurada por meio do teste de 1-RM e a aquisição da AST, espessura muscular (EM), ângulo de penação (AP) e comprimento do fascículo (CF) do VL foi realizada por meio de imagens de ultrassonografia. O programa de treinamento foi composto por 10 semanas com intervalo mínimo de 72 horas entre os treinos. A mensuração da ativação muscular foi realizada por eletromiografia de superfície (EMG) e das concentrações de desoxihemoglobina ([HHb]) e hemoglobina oxigenada ([HbO2]), por meio do near-infrared espectroscopy (NIRS) do VL durante a sessão de treinamento com carga relativa obtida após o teste de 1-RM, antes (T1), após cinco (T2) e dez semanas (T3) do programa de treinamento. Resultados: O volume total (VT) do treinamento foi maior para TFAI e TFAI-RFS comparado ao TFBI-RFS. Não houve diferença entre os grupos em relação ao aumento da 1-RM, AST, EM, AP. Porém, o CF apresentou maior aumento para TFAI-RFS comparado ao TFAI e TFBI-RFS. Em relação à amplitude da EMG, o grupo TFAI-RFS apresentou maiores valores que o TFAI e TFBI-RFS. Por outro lado, as [HHb] foram maiores para o TFAI-RFS e TFBI-RFS, entretanto não houve diferença entre os grupos na redução das [HbO2 ]. Conclusão: O nível de hipóxia local não influência a magnitude do aumento da ativação, força, massa muscular e alterações na arquiteura muscular decorrente do treinamento de força. Entretanto, a adição da hipóxia local parece ter uma maior contribuição para as adaptações decorrentes do treinamento de força de baixa em relação ao de alta intensidade.
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Lindauer, Ute. "Mechanismen und Mediatoren der neurovaskulären Kopplung im Gehirn." Doctoral thesis, Humboldt-Universität zu Berlin, Medizinische Fakultät - Universitätsklinikum Charité, 2001. http://dx.doi.org/10.18452/13764.
Full textAbstract:
Zwischen neuronaler und glialer Aktivierung, dem Energiemetabolismus und dem zerebralen Gefäßbett besteht eine enge Beziehung - als Phänomen der neurometabolischen und neurovaskulären Kopplung bekannt. Diese Korrelation von elektrischer und metabolischer Aktivität sowie dem regionalen zerebralen Blutfluß besteht räumliche und zeitliche fokussiert und ist charakteristisch für das Gehirn. Das Verständnis um die Mechanismen und Mediatoren der neurovaskulären Kopplung ist von grundlegender Bedeutung für die korrekte Interpretation moderner bildgebender Verfahren im klinischen Einsatz. Ein Schwerpunkt der Untersuchungen lag in der Überprüfung der Hypothese eines frühen Sauerstoff-oder Glukose-Mangels im Gewebe unter funktioneller Stimulation als mögliches primäres Signal für eine nachfolgende vaskuläre Antwort. Anhand der Befunde kann jedoch ausgeschlossen werden, daß ein möglicherweise kurzzeitig auftretender Substratmangel im Gewebe registriert wird, und auf diesem Wege die Blutflußantwort auf funktionelle Stimulation initiiert wird. Die Frage nach dem eigentlichen Signal für die Blutflußantwort und dem primären Ort der Regulation (Arteriole, Kapillare, Venole) bleibt weiterhin ungeklärt. Die qualitative wie auch quantitative Charakterisierung des Verlaufs der Blutfluß- und Blutoxygenierungsveränderungen unter somatosensorischer Stimulation bildet die Grundlage für die Untersuchung von Veränderungen dieses Musters unter pathophyiologischen Bedingungen als sogenannter Fingerabdruck spezifischer zerebraler Schädigungen. Im Rahmen des zweiten Schwerpunkts beschäftigt sich vorliegende Arbeit mit der Rolle des Bioradikals Stickstoffmonoxid (NO) bei der neurovaskulären Kopplung. Ein im kortikalen Gewebe physiologisch vorhandener basaler NO Spiegel moduliert über die Bereitstellung einer basalen cyclischen Guanosin-3',5'-Monophosphat (cGMP) Konzentration vornehmlich in glatten Gefäßmuskelzellen die Reaktivtät zerebraler Gefäße sowohl auf globale vasodilatatorische Stimuli wie die Hyperkapnie als auch auf funktionelle Aktivität wie die Whisker-Stimulation der Ratte. Da die Bereitstellung des basalen NO / cGMP Spiegels im zerebralen Gewebe für physiologische vaskuläre Antworten von grundlegender Bedeutung ist, ist zu erwarten, daß eine Störung desselben durch pathophysiologische Vorgänge weitreichende Folgen für die adequate Versorgung aktivierter Hirnareale haben dürfte.<br>A tight relation exists between neuronal and glial cell activation, cerebral energy metabolism, and cerebral vasculature - a phenomenon known as neurometabolic and neurovascular coupling. The correlation of electrical and metabolic activity, and regional cerebral blood flow occurs at high temporal and spatial resolution, and is characteristic for the brain. We need to understand the physiology of neurometabolic and neurovascular coupling to fully exploit the potential of modern functional brain imaging, which utilizes vascular responses to map brain activity. Therefore, understanding the signalling cascade of regional vasodilation due to functional activation is of great importance. In the present work, we have shown that there is no evidence neither for an early deoxygenation nor for an early decrease in glucose concentration in the tissue at the onset of increased neuronal activity. The first event inducing regional cerebral blood flow increase as well as the vascular compartment, at which vasodilation starts (arteriole, capillary, venule), is still not known so far and has to be further investigated. In disease neurovascular coupling may be disturbed, while this disturbance may itself further contribute to tissue damage. Therefore a thorough elucidation of the physiology and pathophysiology of neurometabolic and neurovascular coupling may contribute to the development of treatment strategies in acute and chronic CNS disorders. Beside the mechanisms, little is known concerning the mediators of neurovascular coupling. The involvement of the highly diffusible vasodilator bioradical nitric oxide (NO) in the regulation of regional cerebral blood flow is widely accepted. In the present work, it has been shown that NO acts as a modulator rather than a mediator of vascular relaxation due to functional activation or systemic hypercapnia in the cerebral cortex, permitting vasodilation mediated by other agents. This modulation mainly occurs via a basal cyclic guanosin-3',5'-monophosphate (cGMP) production within the vascular smooth muscle cell. The basal modulatory concentration of NO / cyclic GMP may be disturbed during cerebrovascular disease, leading to a mismatch of regional cerebral blood flow and metabolic demand.
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Lachaux, Julie. "Un oxygénateur microfluidique intégré et compact, à haute efficacité de transfert de gaz." Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPAST063.
Full textAbstract:
Le poumon est un organe vital dont les pathologies au stade terminal peuvent induire une insuffisance circulatoire avec une défaillance cardiaque droite secondaire. Concernant les options thérapeutiques disponibles, des oxygénateurs sanguins macroscopiques basés sur la technologie des membranes extracorporelles (ECMO) sont actuellement utilisés au sein d'une unité de soins intensifs. Ces oxygénateurs doivent être remplacés en quelques semaines en raison de la coagulation dans le système.Dans ce contexte, le but de mon doctorat était de développer un dispositif microfluidique pour l'oxygénation du sang, qui présente une grande surface d'échange gazeux et capable de soutenir une endothélialisation durable à long terme des microcapillaires sanguins améliorant son hémocompatibilité pour les applications cliniques.Des calculs numériques basés sur le modèle d’échange gazeux de Potkay et coll. ont permis de comprendre le rôle de chaque paramètre géométrique sur l’échange gazeux et, donc, de dimensionner au mieux le système tri-couches « microcapillaire de sang / membrane / microcanal de gaz ».J’ai ensuite mis au point un protocole de microfabrication qui permet d’intégrer une membrane fine de polymère de très grande surface, et de fabriquer des oxygénateurs robustes et étanches sous pression.Les performances d’échange gazeux mesurées avec du sang veineux de cochon sont remarquables, tant pour les tri-couches unitaires que pour les structures empilées, avec un faible volume d’injection et une oxygénation élevée (379 ml O2/min/m²) à débit élevé (15ml/min). Ces résultats expérimentaux ont pu être comparés aux calculs numériques. Enfin, avec une géométrie optimisée pour minimiser la contrainte de cisaillement, un protocole d’endothélialisation durable dans les capillaires sanguins a été proposé<br>End-stage lung diseases may result in death either by oxygenation and carbon dioxide exchange insufficiency or by right heart failure. Concerning the therapeutic options currently available, macroscopic blood oxygenators based on extracorporeal membrane (ECMO) technology are currently used. However, the environment of an intensive care unit is still required. Modern oxygenators need to be exchanged within a couple of weeks because of clotting.In this context, the goal of my PhD was the development of a novel microfluidic device for blood oxygenation, which exhibits a large surface area of gas exchange and can support long-term sustainable endothelialization of blood microcapillaries enhancing its hemo-compatibility for clinical applications. Numerical calculations based on the gas exchange model of Potkay et al. helped to best size the three-layer "blood microcapillary / membrane / gas microchannel" system.I then developed a microfabrication protocol that allows the integration of a thin polymer membrane with a very large surface area, producing robust sealed oxygenators.The gas exchange performances achieved with venous pig blood are remarkable both for unit trilayers, and for stacked structures with a low reduced injection volume, high oxygenation (379 ml O2 / min / m²) at a flow rate high (15 ml/min). These experimental results could be compared to numerical calculations. Finally, with an optimized geometry minimizing shear stress, a sustainable endothelialization protocol in blood capillaries has been proposed
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Duany, John. "Predicting Cognitive Workload with Measures from Functional Near-Infrared Spectroscopy (fNIRS) and Heart Rate." Honors in the Major Thesis, University of Central Florida, 2013. http://digital.library.ucf.edu/cdm/ref/collection/ETH/id/942.
Full textAbstract:
The objective of this study was to assess low to high levels of Cognitive Workload by measuring heart rate and cortical blood flow in real-time. Four conditions were implemented into a within-subjects experimental design. Two conditions of difficulty and two conditions of trial order were used to illicit different levels of workload which will be analyzed with psychophysiological equipment. Functional Near-Infrared Spectroscopy (fNIRS) has become more prominent for measuring the blood oxygenation levels in the prefrontal cortex of individuals operating in hazardous work environments, students with learning disabilities, and in research for military training. This is due to the fNIR device being highly mobile, inexpensive, and able to produce a high-spatial resolution of the dorsolateral prefrontal cortex during executive functioning. Heart Rate will be measured by an Electrocardiogram, which will be used in concordance with fNIR oxygenation levels to predict if an individual is in a condition that produces low or high mental workload. Successfully utilizing heart rate and blood oxygenation data as predictors of cognitive workload may validate implementing multiple physiological devices together in real-time and may be a more accurate solution for preventing excessive workload.<br>B.S.<br>Bachelors<br>Sciences<br>Psychology
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Cheng, Ran. "NONINVASIVE NEAR-INFRARED DIFFUSE OPTICAL MONITORING OF CEREBRAL HEMODYNAMICS AND AUTOREGULATION." UKnowledge, 2013. http://uknowledge.uky.edu/cbme_etds/9.
Full textAbstract:
Many cerebral diseases are associated with abnormal cerebral hemodynamics and impaired cerebral autoregulation (CA). CA is a mechanism to maintain cerebral blood flow (CBF) stable when mean arterial pressure (MAP) fluctuates. Evaluating these abnormalities requires direct measurements of cerebral hemodynamics and MAP. Several near-infrared diffuse optical instruments have been developed in our laboratory for hemodynamic measurements including near-infrared spectroscopy (NIRS), diffuse correlation spectroscopy (DCS), hybrid NIRS/DCS, and dual-wavelength DCS flow-oximeter. We utilized these noninvasive technologies to quantify CBF and cerebral oxygenation in different populations under different physiological conditions/manipulations. A commercial finger plethysmograph was used to continuously monitor MAP. For investigating the impact of obstructive sleep apnea (OSA) on cerebral hemodynamics and CA, a portable DCS device was used to monitor relative changes of CBF (rCBF) during bilateral thigh cuff occlusion. Compared to healthy controls, smaller reductions in rCBF and MAP following cuff deflation were observed in patients with OSA, which might result from the impaired vasodilation. However, dynamic CAs quantified in time-domain (defined by rCBF drop/MAP drop) were not significantly different between the two groups. We also evaluated dynamic CA in frequency-domain, i.e., to quantify the phase shifts of low frequency oscillations (LFOs) at 0.1 Hz between cerebral hemodynamics and MAP under 3 different physiological conditions (i.e., supine resting, head-up tilt (HUT), paced breathing). To capture dynamic LFOs, a hybrid NIRS/DCS device was upgraded to achieve faster sampling rate and better signal-to-noise. We determined the best hemodynamic parameters (i.e., CBF, oxygenated and total hemoglobin concentrations) among the measured variables and optimal physiological condition (HUT) for detecting LFOs in healthy subjects. Finally, a novel dual-wavelength DCS flow-oximeter was developed to monitor cerebral hemodynamics during HUT-induced vasovagal presyncope (VVS) in healthy subjects. rCBF was found to have the best sensitivity for the assessment of VVS among the measured variables and was likely the final trigger of VVS. A threshold of ~50% rCBF decline was observed which can completely separate subjects with or without presyncope, suggesting its potential role for predicting VVS. With further development and applications, NIRS/DCS techniques are expected to have significant impacts on the evaluation of cerebral hemodynamics and autoregulation.