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Aladangady, Dr Narendra. "Blood volume of the newborn infant." Thesis, Queen Mary, University of London, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.515517.
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Stefanovic, Bojana. "Functional magnetic resonance imaging of cerebral blood volume." Thesis, McGill University, 2004. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=85650.
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This dissertation describes a novel method for quantifying venous cerebral blood volume (CBVv) changes accompanying normal functional activation and employs quantitative functional magnetic resonance imaging (fMRI) methods to study the hemodynamic and metabolic changes accompanying neuronal inhibition. An in vivo occipital lobe relaxometry study was performed first to investigate the dependence of the spin-spin relaxation time constant of tissue, T2tissue , on the refocusing interval over the range of interest and thus test the basis of the proposed CBVv method. The small decrease of the apparent T2tissue with refocusing interval elongation is consistent with blood being the only significant source of refocusing interval dependence of apparent T2 in grey and white matter of the occipital lobe. In ensuing in vitro blood relaxometry studies, ensemble fitting of the entire set of T2blood estimates, obtained over an extensive range of blood oxygenation levels and refocusing intervals, was performed using both the fast chemical exchange model and the model of diffusion in weak magnetic field inhomogeneities. The results support the application of a diffusion model in describing the deoxyhemoglobin-induced enhancement in blood transverse relaxation rate at 1.5 T. Given the uniqueness of T2blood dependence on the refocusing rates over the range of interest, the novel CBVv method - venous refocusing for volume estimation (VERVE) - successfully isolates the blood signal by refocusing rate variation. A model of functional brain activation was developed and in vitro blood relaxometry data used to assess the effect of the intravascular spin-echo blood oxygenation level dependent (BOLD) contrast on the activation-induced VERVE signal change, allowing robust estimation of venous CBV changes. The method was demonstrated in a visual stimulation study of healthy young adults, where an average venous blood volume in the visual cortex increase was estimated
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Chan, Fang-Chiat D. "Non-invasive venous oximetry through venous blood volume modulation." Thesis, Loughborough University, 2002. https://dspace.lboro.ac.uk/2134/7607.
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For decades, the monitoring of mixed venous oxygen saturation has been done invasively using fibre-optic catheters. This procedure is not without risk as complications may arise from catheterization. This thesis describes an alternative and novel means of monitoring venous oxygen saturation. The technique outlined involves inducing regular modulations of the venous blood volume and the associated measurement of those modulations using an optical sensor. Just as pulse oximetry utilizes the natural arterial pulse to perform spectral analysis of the peripheral blood in order to estimate the arterial blood oxygen saturation, the new venous oximetry technique uses the artificially generated pulse to perform the task of measuring peripheral venous oxygen saturation. This thesis explores and investigates the feasibility of this new venous oximetry technique. A heuristic model was first developed to predict the effects of introducing an artificially generated pulsatile signal in the venous system. The effect on the underlying natural arterial pulsation was also examined. Experiments were then conducted to justify and interpret the model developed. Other experiments were also conducted to optimize the design of the artificial pulse-based venous oximeter, to explore the effects of prolonged modulation of the venous system and to establish evidence that the measurements made were indeed related to venous oxygen saturation. It is concluded that the new venous oximetry technique is indeed feasible and with further research and development would one day replace the current invasive method.
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Evans, Jonathan M. "Measurement of blood flow volume rate by Doppler ultrasound." Thesis, University of Bristol, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.292441.
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Heieis, Mark Rudolf Alois. "Blood volume distribution in and bioenergetics of swimming and diving ducks." Thesis, University of British Columbia, 1987. http://hdl.handle.net/2429/26417.
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Blood flow distribution during forced and voluntary diving in ducks, and the energetic cost of diving was investigated.
It has been suggested that in order for the leg muscles to generate enough power for ducks to dive, blood flow to those tissues must be maintained. A technique to determine blood flow distribution which could be used during voluntary diving was first developed and tested during forced laboratory dives of ducks. This technique was then used to determine the blood flow distribution during voluntary diving. Regional blood flow distribution was visualized by utilizing a radioactive tracer technique (macro aggregated albumin labelled with ⁹⁹ⅿ technetium). The tracer when injected into an animal is trapped and held by capillaries. During forced dives in dabbling (Anas platyrhynchos) and diving (Aythya affinis) ducks the blood flow distribution was found to be restricted to the thoracic and head areas. Whereas during a voluntary dive in A. affinis blood flow distribution was shown to be preferentially directed towards three tissue areas, the heart, brain, and active leg muscles.
The work required to dive was determined from the measurement of subsurface drag forces and buoyancy in A. affinis. Subsurface drag increased as a nonlinear function of swimming velocity. At a velocity of 1 m•s⁻¹, the drag force was approximately 1.067 N. The average measured buoyant force of 11 ducks was 0.953 N. The calculated mechanical work done by ducks during a 14.4 s unrestrained dive was 9.34 J. The power output during voluntary was estimated to be 0.751 W (0.0374 ml 0₂•s⁻¹). During diving buoyancy is clearly the dominant force (8.8 J) against which ducks have to work while drag (0.54 J) adds little (~6%) to the energetic cost of diving.Science, Faculty of
Zoology, Department of
Graduate
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Gainer, John. "Control and awareness of digital blood volume pulse : a comparison of headache and non-headache subjects." Thesis, McGill University, 1986. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=74027.
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Cenic, Aleksa. "Changes in cerebral blood volume and blood flow in brain tumours during propofol or isoflurane anaesthesia and hyperventilation." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/mq30759.pdf.
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Henderson, Elizabeth. "Measurement of blood flow, blood volume and capillary permeability in breast tumours using contrast-enhanced magnetic resonance imaging." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0020/NQ58134.pdf.
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Mauritz, Jakob Martin Andreas. "Homeostasis and volume regulation in the Plasmodium falciparum infected red blood cell." Thesis, University of Cambridge, 2011. https://www.repository.cam.ac.uk/handle/1810/240497.
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The thesis reports on the application of advanced microanalytical techniques to answer a fundamental open question on the homeostasis of Plasmodium falciparum infected red blood cells, namely how infected cells retain their integrity for the duration of the parasite asexual reproduction cycle. The volume and shape changes of infected cells were measured and characterized at femtolitre resolution throughout the intraerythrocytic cycle using confocal microscopy. Fluorescence lifetime imaging and electron probe X-ray microanalysis were applied for the quantification of intracellular haemoglobin and electrolyte concentrations. The cytomechanical properties of uninfected and infected red cells were studied using a novel optical stretcher device, which enabled individual cells to be trapped and manipulated optomechanically in microfluidic channels. Combined, these methods offered a unique insight into the homeostatic and rheological behaviour of malaria-infected red cells. The results were analysed by comparison with predictions from a detailed physiological model of the homeostasis and volume regulation of infected cells, providing broad support to the view that excess haemoglobin consumptions by the parasite was necessary for the integrity of infected cells (the colloidosmotic hypothesis). The dissertation is introduced with an overview of malaria, red blood cells homeostasis and the changes induced by Plasmodium falciparum infection. In the following, this description is extended to an in-depth theoretical analysis of the infected red blood cell homeostasis, from which the need to characterise certain parameters arises. The subsequent chapters address sequentially the assessment of the haemoglobin and electrolyte concentration, cell shape and volume changes and ultimately alterations in cell elasticity. The experimental part is complemented with a comparison of the resulting data to the predictions from the theoretical analysis and an outlook on future work.
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Huber, Laurentius. "Mapping Human Brain Activity by Functional Magnetic Resonance Imaging of Blood Volume." Doctoral thesis, Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-165252.
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This dissertation describes the development, implementation, validation, optimization, and application, of a noninvasive and quantitative method for measuring cerebral blood volume changes with functional magnetic resonance imaging (fMRI) for mapping of neural activity changes.
Since its inception over twenty years ago, the field of fMRI has grown in usage, sophistication, range of applications, and impact. Nevertheless it has yet to exploit its full potential regarding, spatiotemporal resolution, signal specificity, and quantifiability of hemodynamic changes. By utilization of a new MR pulse sequence, new concepts of radio frequency pulses, and high magnetic fields (7 T), a novel fMRI method named SS-SI VASO is presented here that overcomes sensitivity limitations of other noninvasive quantitative imaging methods. In order to validate that its signal represents changes in cerebral blood volume without other contaminations, SS-SI VASO is implemented in animal models for a close comparison with established, but invasive methods. A good agreement of blood volume sensitivity has been found with the new method compared to the established ones. After its validation, the SS-SI VASO method and its unprecedented sensitivity was used to localize and quantify hemodynamic changes in applications where conventional oxygenation based fMRI methods are limited. (A) SS-SI VASO was used to investigate biophysical aspects of actively controlled arteries and passive balloon-like veins during activity induced hemodynamic changes. (B) SS-SI VASO was used to provide insights whether the interplay of neural activity and resultant vascular response are the same for tasks that increase neural activity compared to tasks that suppress neural activity. (C) SS-SI VASO was used to calibrate conventional oxygenation based fMRI to quantify local changes in oxygen metabolism. (D) The high sensitivity of SS-SI VASO was further used to obtain sub-millimeter resolutions and estimate activity changes between cortical layers. This enables to address questions not only where the brain is activated but also how and whereby this activity is evoked. The implementation and application of this new SS-SI VASO fMRI method is a major step forward for the field of imaging neuroscience; it demonstrates that the current limitations of fMRI can be even overcome with respect to quantifiability, spatial specificity and distinguishing between vascular and neuronal phenomena.
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Weaver, Yasmin Rozina. "Volume regulation in teleost red blood cells : a role for protein phosphorylation." Thesis, University of Liverpool, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.338582.
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Rochette, Lynne M. "Resting hemodynamic function and reactivity to acute stress : the influence of hydration on cardiac function and plasma volume /." Ohio : Ohio University, 2004. http://www.ohiolink.edu/etd/view.cgi?ohiou1108392572.
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Tjandra, Teddy. "Towards quantitative MR-based functional imaging : evaluation of blood oxygen level dependent (BOLD), perfusion and blood volume imaging methods." Thesis, University of Oxford, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.413215.
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Tattersall, James Erskine. "Atrial natriuretic peptide : its measurement in plasma and role in blood volume homeostasis." Thesis, Imperial College London, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.338515.
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Rothenbühler, Andreas Fischbacher Andreas. "Body sodium/blood volume state in normotensive members of mormotensive and hypertensive families /." [S.l : s.n.], 1985. http://www.ub.unibe.ch/content/bibliotheken_sammlungen/sondersammlungen/dissen_bestellformular/index_ger.html.
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Funkquist, Pia. "Physiological responses to exercise in standardbred trotters with special reference to total blood volume /." Uppsala : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 1999. http://epsilon.slu.se/avh/1999/91-576-5906-0.pdf.
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Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv.Bilagan utgöres av sammanfattnig på svenska med titeln: Fysiologiskt svar på arbete hos varmblodiga travhästar i relation till total blodvolym. Härtill 5 uppsatser.
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Chen, Jing. "Cerebral venous blood volume: methodology for In Vivo measurement and implications for BOLD fMRI." Thesis, McGill University, 2009. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=40666.
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Changes in cerebral venous blood volume (DCBVv) is a critical component of the BOLD fMRI signal (instead of total DCBV), but its role has remained relatively unexplored, predominantly because measuring CBVv non-invasively is challenging. Motivated by this challenge, this thesis focuses on the development and use of the venous refocusing for volume estimation (VERVE) technique to non-invasively measure DCBVv. Driven by the substantial signal-to-noise (SNR) gain at high field, VERVE was re-designed for 3 T. This technique is strongly field-dependent through its reliance on venous blood transverse relaxation (T2) variations as a function of the Carr-Purcell Meiboom-Gill (CPMG) refocusing interval and blood oxygenation. To characterize this dependence, human whole blood T2 relaxometry was performed at 3 T. The results reveal significantly enhanced blood T2 dependence relative to 1.5 T, one best modelled as a diffusion process. In addition, human grey and white matter T2 relaxometry results support venous blood T2 variation being the predominant source of VERVE contrast at 3 T. The subsequent design of VERVE was based on the blood relaxometry results. Also, to minimize signal biases due to gradient-echo BOLD effects, greatly amplified at 3 T, a turbo spin-echo approach was adopted, further boosting SNR. VERVE was then used with arterial spin labeling (ASL) to assess the steady-state venous flow-volume relationship in humans under visual and sensorimotor stimulation. The results demonstrated a spatially-invariant flow-volume relationship characterized by a power-law coefficient (a) of 0.23, significantly lower than Grubb’s value of 0.38 (derived using total DCBV). The assumption of the latter in calibrated BOLD introduced a significant underestimation in cerebral oxygen metabolism changes (DCMRO2). Finally, the interactions giving rise to the controversial BOLD post-stimulus undershoot were examined with respect to the prevalent biomechanical, metabolic and neuronLes changements du volume sanguin cérébral veineux (DCBVv) est un élément essentiel du signal BOLD (par opposition à l’ensemble de DCBV). Pourtant, jusqu'ici le rôle du CBVv est resté relativement inexploré, et ce du aux difficultés liées aux mesures non-invasives du CBVv. Motivée par ce défi, cette thèse se rapporte sur le développement et l'utilisation de la méthode VERVE (refocalisation veineuse pour l’estimation du volume), qui permet l’estimation non-invasive de DCBVv. D’abord, l’augmentation importante du rapport signal-sur-bruit (SNR) aux champs magnétiques élevés a mené à réviser VERVE pour 3 T. Le contraste VERVE est basé sur les variations du temps de relaxation transversale (T2) sanguin veineux en fonction de l’intervalle de refocalisation Carr-Purcell Meiboom-Gill (CPMG) et de l’oxygénation sanguine. Pour caractériser cette dépendance, qui dépend fortement du champ magnétique, une étude relaxométrique du sang humain a été réalisé à 3 T. Les résultats indiquent que la dépendance du T2 sanguin est amplifiée de façon importante entre 1.5 T et 3 T. Un modèle de diffusion décrit le mieux cette dépendance. D’autre part, une étude relaxométrique de la matière grise et blanche a été réalisée, confirmant la dominance de l’effet T2 sanguin dans le contraste VERVE. La composition de VERVE se rapporte aux résultats relaxométriques sanguins. En plus, afin de minimiser l’effet de l’écho de gradient, amplifié à 3 T, une approche turbo spin-écho a été adoptée. VERVE est ensuite utilisée avec le marquage des spins artériels (ASL) pour mesurer les changements du CBVv et du débit sanguin cérébral (CBF) chez les sujets sains lors de stimulations visuelles et sensorimotrices. Les résultats démontrent une relation débit-volume invariante à travers le cortex, caractérisée par a = 0.23, inférieure à la valeur de Grubb (0.38, calculée a partir du CBV total). En employant cett
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De, Villiers Anna Magdalena. "Modelling blood flow in large arteries using the finite volume method / de Villiers A.M." Thesis, North-West University, 2012. http://hdl.handle.net/10394/8159.
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The purpose of this research is the development of a one–dimensional (1D) computer code that
models blood flow through large arteries. There are many of these models in literature, the
majority is solved with the finite element method. The problem is analogous to a compressible
liquid in a pipe network. Methods to solve the pipe network flow problem have evolved over
the years. One of these methods, which can handle discontinuities and branching naturally to
solve the blood flow problem, was used in this research.
The blood flow problem can be modelled by solving mass flow, momentum conservation and
the interaction between the blood flow and the arterial wall. In essence we are looking at
two problems in two time scales, namely mass flow and the propagation of the pressure pulse.
The mass flow rate of the blood is not very fast – it takes a blood particle approximately one
minute to travel to the organs and back. Everytime the heart beats, it sends a 'shockwave'
through the system. These waves or pulses propagate at speeds at least three orders higher
than the blood flow. When these pressure waves reach a discontinuity or branch in the arterial
network, part of the wave is reflected.
The method used for this study discretises the partial differential equations by using a staggered
grid and the finite volume method. An iterative method similar to the Semi Implicit
Method for Pressure Linked Equations (SIMPLE) was used to solve the discretised equations.
By using the characteristic system, characteristic variables that are constant along characteristic
lines can be derived. These variables represent forward and backward travelling wave
fronts. By expressing the boundary conditions in terms of these variables, rather than in
terms of flow, area and pressure, we can prescribe non–reflecting boundary conditions. This
way pressure waves can travel out of the computational domain unhindered. Discontinuities
and branching are handled naturally because of the staggered grid discretisation.
A computer code was written in Octave to solve the discretised equations for a number of
test cases. The results show that when a small input pressure wave is prescribed, the solution
behaves linearly. When a large input pressure wave is prescribed the solution behaves nonlinearly.
The non–reflecting boundary conditions work perfectly for the linear test case, but
a small portion of the outgoing wave is reflected for the non–linear test case. Discontinuities
and branching were handled satisfactorily with the code for a number of test cases.Thesis (MIng (Mechanical Engineering))--North-West University, Potchefstroom Campus, 2012.
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Chamney, Paul William. "The application of blood volume monitoring for optimisation of fluid status in haemodialysis patients." Thesis, University of Hertfordshire, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.323434.
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Bolke, Mark Edward. "Renal Responses to Differential Rates of Blood Volume Expansion in the Toad, Bufo marinus." PDXScholar, 1995. https://pdxscholar.library.pdx.edu/open_access_etds/4973.
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Three aspects of renal function were measured in the toad, Bufo marinus (N=lO): (1) effect of rate of blood volume expansion on renal functions (UFR; GFR; urine and plasma ion concentrations; and ion excretion rates), (2) effect of hypo- and hyperosmotic blood volume expansions on renal functions, and (3) role of GFR and tubular processes in the differential response of UFR under different osmotic expansion stresses. Renal responses to differential rates of blood volume expansion have not been investigated in amphibians. Rate responses will be analyzed considering effects: ( 1) during infusion (neural, or, short term regulation of extracellular fluid volume) and (2) post infusion (hormonal, or, long term regulation of extracellular fluid volume). Volume expansions were administered with hypoosmotic (0.4%) saline and hyperosmotic (1.4%) saline, and ranged in rate from 4.0 to 20.6 ml/kg/min. This protocol is designed to present volume regulatory mechanisms with increased volume stimuli and different osmotic stimuli. Overall, infusion rate had no significant effects on renal responses measured: urine flow rate (UFR); glomerular filtration rate (GFR); urine and plasma ion concentrations; natriuresis; or kaliuresis. This was true for the infusion period and for the observed post infusion period (90 min). Rate was correlated with GFR in the hypoosmotic group (r=0.30, p=0.04) and natriuresis in the hyperosmotic group (r=0.34, p=0.03). A significant positive correlation was observed between UFR and GFR. Relative to treatment, UFR differed significantly; GFR response was inherently similar despite differences at individual intervals, indicating UFR differences between the treatments is due to tubular processes. Responses to hypoosmotic infusion included a significant diuresis, natriuresis, and a decreased urine sodium concentration, relative to hyperosmotic infusion. At low UFRs the hyperosmotic group produced urine relatively concentrated in sodium. Urine sodium concentration and UFR were positively correlated in the hypoosmotic infusion group -- at high UFRs, kidneys were unable to produce a dilute urine.
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Bexfield, Nathan Alex. "Plasma Volume and Albumin mRNA Expression in Exercise Trained Rats." Diss., CLICK HERE for online access, 2007. http://contentdm.lib.byu.edu/ETD/image/etd2085.pdf.
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Eriksson, Jonatan, Ann F. Bolger, Tino Ebbers, and Carl-Johan Carlhäll. "Four-dimensional blood flow-specific markers of LV dysfunction in dilated cardiomyopathy." Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-87616.
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Aims : Patients with mild heart failure (HF) who are clinically compensated may have normal left ventricular (LV) stroke volume (SV). Despite this, altered intra-ventricular flow patterns have been recognized in these subjects. We hypothesized that, compared with normal LVs, flow in myopathic LVs would demonstrate a smaller proportion of inflow volume passing directly to ejection and diminished the end-diastolic preservation of the inflow kinetic energy (KE). Methods and results : In 10 patients with dilated cardiomyopathy (DCM) (49 ± 14 years, six females) and 10 healthy subjects (44 ± 17 years, four females), four-dimensional MRI velocity and morphological data were acquired. A previously validated method was used to separate the LV end-diastolic volume (EDV) into four flow components based on the blood's locations at the beginning and end of the cardiac cycle. KE was calculated over the cardiac cycle for each component. The EDV was larger (P = 0.021) and the ejection fraction smaller (P < 0.001) in DCM compared with healthy subjects; the SV was equivalent (DCM: 77 ± 19, healthy: 79 ± 16 mL). The proportion of the total LV inflow that passed directly to ejection was smaller in DCM (P = 0.000), but the end-diastolic KE/mL of the direct flow was not different in the two groups (NS). Conclusion : Despite equivalent LVSVs, HF patients with mild LV remodelling demonstrate altered diastolic flow routes through the LV and impaired preservation of inflow KE at pre-systole compared with healthy subjects. These unique flow-specific changes in the flow route and energetics are detectable despite clinical compensation, and may prove useful as subclinical markers of LV dysfunction.
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Al-Othman, Abdullah Abdulrahman 1961. "Influence of copper deficiency on plasma lipoproteins and the development of enlarged plasma volume and cholesterol pool size." Thesis, The University of Arizona, 1989. http://hdl.handle.net/10150/277117.
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Two studies were designed to investigate the time course development of enlarged plasma volume and cholesterol pool size in copper (Cu)-deficient rats as well as influence of Cu deficiency on the lipid composition of lipoproteins. Rats were randomly assigned to three dietary Cu treatments (deficient, marginal, and adequate) in the Study I and two dietary Cu treatments (deficient and adequate) in Study II. Enlargement of plasma volume and cholesterol pool size were established prior to the increase in plasma cholesterol concentration. Cu concentration was decreased, whereas iron and zinc concentrations were increased in the organs of Cu-deficient and Cu-marginal rats. The plasma pool size of VLDL triglyceride was elevated 6-fold, protein and phospholipid were unaltered, and cholesterol was reduced 36%. The plasma pool size of lipid and protein components of HDL and LDL fractions were markedly elevated in Cu-deficient rats.
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Nelson, William Bradley. "Exercise Induced Hypervolemia: Role of Exercise Mode." Diss., CLICK HERE for online access, 2007. http://contentdm.lib.byu.edu/ETD/image/etd2128.pdf.
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Zhai, Guihua Lin Weili. "Effects of chronic hypertension and acute cerebral ischemia on blood-brain barrier permeability, brain water content, and cerebral blood volume using MRI." Chapel Hill, N.C. : University of North Carolina at Chapel Hill, 2006. http://dc.lib.unc.edu/u?/etd,1024.
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Thesis (Ph. D.)--University of North Carolina at Chapel Hill, 2007.Title from electronic title page (viewed Dec. 18, 2007). "... in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Department of Biomedical Engineering." Discipline: Biomedical Engineering; Department/School: Medicine.
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Alomari, Abdul-Hakeem Hussein Electrical Engineering & Telecommunications Faculty of Engineering UNSW. "Spectral analysis of arterial blood prssure and stroke volume variability: the role of Calcium channel blockers and sensitizers." Publisher:University of New South Wales. Electrical Engineering & Telecommunications, 2008. http://handle.unsw.edu.au/1959.4/43923.
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In this thesis, we included results from two studies. The first one considered the effects of the blood volume changes, during blood donation, on the heart rate variability (HRV) measured, non-invasively, form electrocardiographic (ECG) and photoplethysmographic (PPG) signals. Our results showed that, during blood donation, there were no significant changes in the pulsatile area of PPG signal, while heart rate increased. No significant changes were noticed in HRV extracted from both signals. Error analysis between the HRV extracted from ECG and peak interval variability (PIV) suggested that the error during blood donation was increased which means that the use of PIV extracted from PPG signal, used as a replacement diagnostic tool in clinical applications, needs further investigations and should be carefully studied in non-stationary cardiovascular situations such as blood donation. The imbalance between the two branches of the autonomic nervous system, sympathetic and parasympathetic, vagal, may result in a harmful activation of myocardial tissues which cause arrhythmias and sudden cardiac death. Although the study of the sympathovagal balance have been attracting many researchers, further studies are needed to elucidate the effects of many kinds of drugs on the autonomic modulation of the cardiac muscle, specifically, the cells of sinoatrial (SA) node. The aim of the second part of this thesis was to assess the effects of calcium channel blocker (Verapamil), calcium channel sensitizer (Levosimendan), calcium chloride (CaCl2), the combinations of verapamil/ CaCl2, levosimendan/ CaCl2, and noradrenaline infusion on beat-to-beat cardiovascular variability represented, in this research, by systolic blood pressure variability (SBPV), and stroke volume variability (SVV) signals. We used Fat Fourier Transform (FFT) to evaluate the power spectral density of the fluctuations in both signals to evaluate the effects of short-term treatments with those drugs on the sympathovagal balance in normal rats. Then, we compared the spectra obtained from SBPV and SVV to decide which of these fluctuations along with corresponding spectrum was more able to provide a clear feedback about the autonomic nervous system. Our data suggests that there were a significant correlations between low- (LF), mid- (MF), and high-frequency (HF) spectra obtained from SBPV and SVV except between the HF spectra estimated from after the infusion of levosimendan where a poor correlation (r = 0.530, p = 0.281) was noticed. This that both HF components obtained provide different information regarding the autonomic nervous system modulation of the SA node cells, while the results obtained from the rest of experiments showed that both signals provide same information about the modulation of sympathetic and parasympathetic tone due to all stages of different drugs infusion studied in this thesis. Besides that, we found that both spectra may be used to track the fluctuations in the cardiac output as a result of the drugs infusion.
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Kelany, Khaled Elaraby. "Can Hematocrit Levels at Estrus in Dairy Cows and Sheep Be an Indicator for Pregnancy Success?" Thesis, North Dakota State University, 2019. https://hdl.handle.net/10365/31604.
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Despite the major reproductive advances in the livestock industry, prenatal embryonic loss is still one of the major issues that causes substantial economic loss. While there are many tests available to determine pregnancy soon after maternal recognition of pregnancy, most of the prenatal losses are undetectable because it occurs before then. Based on previous research we hypothesized that increased plasma volume around the time of estrus will increase the survivability of the embryo at early stages of gestation. However, our findings indicate that hematocrit levels are not a consistent measurement in determining successful pregnancies.
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Sims, Stacy Teresa, and n/a. "Plasma volume and the physiological response to sodium loading in men and women." University of Otago. School of Physical Education, 2007. http://adt.otago.ac.nz./public/adt-NZDU20070418.143047.
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The metabolic heat generated by exercise must be dissipated to maintain body temperature within narrow physiological limits; during exercise and heat exposure, body water is lost via sweating to enable evaporative cooling of the body. When sweating takes place, total body water is reduced (without the intake of additional fluids) from each fluid compartment due to the free exchange of water between compartments with a concomitant loss of electrolytes, primarily sodium. A series of three investigations were undertaken to evaluate: 1) the efficacy of acute sodium citrate-chloride loading on endurance trained males and females as a viable means to expand extracellular fluid volume, 2) any menstrual cycle effects on renal handling of this sodium load at rest, and 3) if any subsequent hypervolaemia reduces the physiological strain of exercise in warm conditions in both genders. The first investigation examined eight endurance-trained (VO₂[max]: 58 ml�kg⁻��min⁻� (SD 5); 36 y (SD 11)) runners in a randomized double-blind crossover study. The participants ingested a high-sodium (HighNa⁺: 164 mmol Na⁺�L⁻�) or low-sodium (LowNa⁺: 10 mmol Na⁺�L⁻�) beverage (10 ml�kg⁻�) before running to exhaustion at 70% VO₂[max] in warm conditions (32�C, 50% RH, V[a]~1.5 m�s⁻�). Results indicate that HighNa⁺ increased PV before exercise (4.5% (SD 3.7)), calculated from Hct and [Hb]), whereas LowNa⁺ didn�t (0.0% (SD 0.5); P = 0.04), and involved greater time to exercise termination in those who were stopped due to ethical end point of 39.5�C and volitional exhaustion (39.5�C: 57.9 min (SD 6) vs. 46.4 min (SD 4); n = 5, P = 0.04; EXH: 96.1 min (SD 22) vs. 75.3 min (SD 21); n = 3, P = 0.03; HighNa⁺ vs. LowNa⁺ respectively). At equivalent times before exercise termination, HighNa⁺ also involved lower core temperature (38.9 vs. 39.3�C; P = 0.00) and perceived exertion (P = 0.01), and a tendency for lower heart rate (164 vs. 174 bpm; P = 0.08).
The main purpose of the second investigation was to investigate the efficacy of an acute sodium load on endurance trained women�s plasma volume and renal mechanisms across the menstrual cycle at rest. This was evaluated by inducing a sodium-mediated plasma volume expansion using HighNa⁺ at rest during the last high hormone week of the OCP cycle (HH[ocp]) or the late-luteal phase of the natural cycle (LUT[nat]) and during the low hormone sugar pill week of the OCP cycle (SUG[ocp]) or during the early follicular phase of the natural cycle (FOL[nat]. Thirteen women completed the study with one woman on a progestin-only pill (results were used for case study, not statistical analyses) and were assigned to one of two groups: 1) control (NAT, n = 6, 24 y (SD 5), 53 ml�kg�ml⁻� (SD 3)) or oral contraceptive pill (OCP, n = 6, progestin only n = 1, 29 y (SD 6), 51 ml�kg�ml⁻� (SD 2)) group according to their usage status. Across the four-hour post loading time there was greater plasma volume expansion in SUG[ocp] and FOL[nat] vs. LUT[nat] and HH[ocp] (5.06% (SD1.16) vs. 3.35% (SD 0.23), P = 0.02). OCP usage did not reliably alter the hypervolaemic response (P = 0.27), and this was not dependent on phase of cycle (P = 0.32). Plasma volume expansion occurred across both types and phases of the menstrual cycle with evidence that estradiol interactions with AVP, P[osm] and body water retention are stronger in the low hormone phase of the OCP than in the follicular phase of the natural cycle; illustrated by greater overall water retention after an acute sodium+water load.
The third investigation was conducted during the high hormone phase of both OCP and NAT menstrual cycles to further examine sodium-loading effects on the physiological capacity of exhaustive cycling in warm conditions. Thirteen endurance-trained (VO₂[peak] 52 ml�kg⁻��min⁻� (SD 2); 26 y (SD 6), 60.8 kg (SD 5), mean (SD)) cyclists completed this double-blind, crossover experiment during the high hormone phase of the menstrual cycle. Cyclists ingested a concentrated sodium (HighNa⁺: 164 mmol Na⁺�L⁻�) or low-sodium (LowNa⁺: 10 mmol Na⁺�L⁻�) beverage (10 ml�kg⁻�) before cycling to exhaustion at 70% VO₂[max] in warm conditions (32�C, 50% RH, V[a]~5.6 m�s⁻�). HighNa⁺ increased PV before exercise, similar to that of the men in the first investigation, whereas LowNa⁺ didn�t (4.4% (SD 1.2) vs. -1.9% (SD 1.3); P < 0.0001), and involved greater time to exhaustion (98.6 min (SD 25.6) vs. 78.5 min (SD 24.6); P < 0.0001). There was a higher baseline core temperature and faster rate of change for HH[ocp] for both beverage conditions (HighNa⁺: 37.15 (SD 0.6) vs. 36.92�C (SD 0.4); P = 0.05, LowNa⁺: 37.04 (SD 0.6) vs. 36.90�C (SD 0.4), P = 0.05; HH[ocp] vs. LUT[nat], respectively). Through this series of investigations a greater understanding was achieved of fluid balance and the effect of pre-exercise hypervolaemia between genders; pre-exercise ingestion of a concentrated sodium beverage increased plasma volume before exercise and involved less thermoregulatory and the actual and perceived physiological strain during exercise and increased endurance in warm conditions.
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Turner, Dakota. "The Effects of Phenylephrine, Sodium Nitroprusside, andHypoxia on the Heart and Blood Vessels in Danio rerio." University of Akron / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=akron1473699326227566.
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Williams, Donna Ann. "RELATIONSHIP BETWEEN PLASMA VOLUME AND BLOOD LACTATE DURING EXERCISE FOLLOWING SIMULATED WEIGHTLESSNESS (BEDREST DECONDITIONING, ANAEROBIC THRESHOLD)." Thesis, The University of Arizona, 1985. http://hdl.handle.net/10150/275469.
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Boekkooi, Peter Focco. "Aspects of blood volume regulation in pregnancy a study in the awake late-pregnant rat /." Maastricht : Maastricht : Datawyse ; University Library, Maastricht University [Host], 1990. http://arno.unimaas.nl/show.cgi?fid=5600.
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Cohalan, Claire. "Cerebral blood volume changes during human neuronal activation: a comparative study of VASO and VERVE." Thesis, McGill University, 2009. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=66871.
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In this research, two techniques which measure hemodynamic changes during neuronal activation in humans were studied. The Vascular Space Occupancy (VASO) technique indirectly measures changes in total cerebral blood volume (CBV) by measuring the decrease in grey matter signal during activation, in images in which the blood signal is nulled. The Venous Refocusing for Volume Estimation (VERVE) technique measures changes in venous blood volume by exploiting the dependence of partially-deoxygenated blood's T2¬ on the refocusing interval τ180. Using a simultaneous visual and motor task, a (ΔCBV/CBVrest)total of 25.0 ± 13.9 % and a (ΔCBV/CBVrest)¬venous of 3.9 ± 1.6 % were measured using VASO and VERVE, respectively. Though the VASO technique has a high CNR and is simple to implement, its signal has contributions from many compartments other than grey matter. VERVE has fewer deleterious effects, but suffers from a higher power deposition. The activated regions in VERVE overlap better with BOLD activation than the VASO regions do, which, combined with VERVE's specificity to venous CBV changes, make it more appropriate in an investigation of the blood volume contribution to the BOLD signal.Deux techniques visant à mesurer les changements de volume sanguin cérébral durant l'activité neuronale sont étudiées. La première, Vascular Space Occupancy (VASO), mesure l'augmentation de l'ensemble du sang en mesurant la baisse du signal provenant de la matière grise, dans une image où la magnétisation du sang est nulle. La deuxième, Venous Refocusing for Volume Estimation (VERVE), mesure en particulier l'augmentation du volume sanguin veineux en exploitant la dépendance du T2 du sang partiellement deoxygéné sur l'intervalle de refocalisation τ180. Avec une tâche à la fois motrice et visuelle, un (ΔCBV/CBVrepos)totale de 25,0 ± 13,9 % et un (ΔCBV/CBVrepos)¬veineux de 3,9 ± 1,6 % ont été mesurés par VASO et VERVE, respectivement. La méthode VASO est facile à instrumenter, et jouit d'un ratio contraste-bruit plus élevé que VERVE, mais plusieurs compartiments autres que la matière grise contribuent à son signal. Moins d'effets gênants contribuent au signal de VERVE, mais celui-ci souffre d'un taux de puissance déposé élevé, parfois atteignant les limites imposées par la Commission Fédérale des Communications. Le volume activé de VERVE correspond mieux que le volume activé de VASO au volume activé de BOLD. Ce fait, et celui que VERVE mesure spécifiquement le volume veineux, prônent l'utilisation de cette technique dans une analyse de la contribution du volume sanguin au signal BOLD.
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Boltshauser, Rasmus. "Development of a Novel Device for Optimal Sample Blood Volume Collection from Patients with Sepsis." Thesis, KTH, Medicinteknik och hälsosystem, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-279133.
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When performing sepsis diagnosis, the most important preanalytical variable is blood volume. Too little blood increases the risk for false negatives whereas overfilling causes increased risk for false positives. Even though this fact is known, there are case studies showing that in a majority of tests, the taken blood sample volume is not the recommended amount. As previously tried methods have been limited in their ability to tackle the problem this study aimed at creating a technical device to aid healthcare providers with blood volume sample collection. As a base, the double diamond approach by the Design Council was used. This design approach splits up the design process in four distinctly different phases (discover, define, develop, and deliver) all using their own methods to aid the creative process. After completing the discover and define phase it was determined that a non-contact capacitance liquid level sensor could operate as an ideal blood volume sample device. During the development and delivery phase prototypes were created and evaluated. The final results of this work could not give conclusive evidence concerning if a non-contact liquid level sensor could operate as an ideal blood volume collection device. The methodological approach used in this thesis can be used as inspiration for a designer to create a device for a similar or different purpose. Moreover, information from this thesis can also work as reference material to develop a device to perform ideal blood volume sample collection. Such a device would have the potential to be an essential part of the everyday workflow in sample collection from patients with sepsis worldwide and would aid in ensures effective and fast diagnostics.
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Läthén, Gunnar. "Level Set Segmentation and Volume Visualization of Vascular Trees." Doctoral thesis, Linköpings universitet, Medie- och Informationsteknik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-97371.
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Medical imaging is an important part of the clinical workflow. With the increasing amount and complexity of image data comes the need for automatic (or semi-automatic) analysis methods which aid the physician in the exploration of the data. One specific imaging technique is angiography, in which the blood vessels are imaged using an injected contrast agent which increases the contrast between blood and surrounding tissue. In these images, the blood vessels can be viewed as tubular structures with varying diameters. Deviations from this structure are signs of disease, such as stenoses introducing reduced blood flow, or aneurysms with a risk of rupture. This thesis focuses on segmentation and visualization of blood vessels, consituting the vascular tree, in angiography images. Segmentation is the problem of partitioning an image into separate regions. There is no general segmentation method which achieves good results for all possible applications. Instead, algorithms use prior knowledge and data models adapted to the problem at hand for good performance. We study blood vessel segmentation based on a two-step approach. First, we model the vessels as a collection of linear structures which are detected using multi-scale filtering techniques. Second, we develop machine-learning based level set segmentation methods to separate the vessels from the background, based on the output of the filtering. In many applications the three-dimensional structure of the vascular tree has to be presented to a radiologist or a member of the medical staff. For this, a visualization technique such as direct volume rendering is often used. In the case of computed tomography angiography one has to take into account that the image depends on both the geometrical structure of the vascular tree and the varying concentration of the injected contrast agent. The visualization should have an easy to understand interpretation for the user, to make diagnostical interpretations reliable. The mapping from the image data to the visualization should therefore closely follow routines that are commonly used by the radiologist. We developed an automatic method which adapts the visualization locally to the contrast agent, revealing a larger portion of the vascular tree while minimizing the manual intervention required from the radiologist. The effectiveness of this method is evaluated in a user study involving radiologists as domain experts.
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Gibbs, J. M. "The relationship between regional cerebral flow, blood volume and oxygen metabolism in occlusive carotid artery disease." Thesis, University of Cambridge, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.599384.
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Donald, James. "The pathophysiology of haemorrhagic shock and blood volume restitution in a prehepatic model of portal hypertension." Thesis, University of Aberdeen, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.385609.
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Patients with portal hypertension who have bled from oesophageal varices have a mortality of approximately 30&37 . It is a therapeutic paradox that life-saving resuscitation following haemorrhagic shock may be detrimental by causing variceal rebleeding or continued haemorrhage and by inducing gastric erosions. This thesis addresses the hypotheses: i) secondary bleeding from varices in portal hypertension (PHT) is precipitated by blood volume restitution resulting from increased portal pressure, an increase which can be prevented by the somatostatin analogue, SMS 201-995 (Octreotide); ii) erosive gastritis found in patients with varices results from increased susceptibility to mucosal injury, is exacerbated by reperfusion, and is mediated by oxygen-derived free radicals. The three principal approaches employed were initially to establish prehepatic portal hypertension in a rat model by graded portal vein ligation (PVL). Acute PHT (3 days post-PVL) was characterised by high portal pressure and little portasystemic shunting, while chronic PHT (14 days post-PVL) was characterised by lower portal pressure and increased shunting. In anaesthetised hypovolaemic animals, arterial pressure was reduced below 35mmHg for 30 minutes. Following reperfusion, portal pressure increased by up to 34&37 above baseline values. In acute PHT, this was mediated by increased portal venous inflow, whereas in chronic PHT, outflow resistance increased. The rise in portal pressure was prevented by SMS 201-995 (dose-related). Secondly, studies of the gastric mucosa in PHT demonstrated that; it was not more susceptible to injury; injury was dependent on gastric luminal acidity; a gradient of injury existed, and there was no correlation between injury and portal pressure or shunting.
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Nilsson, Anders. "Power Doppler - Principles and Potential Clinical Applications." Doctoral thesis, Uppsala : Institutionen för onkologi, radiologi och klinisk immunologi : Uppsala universitet, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-3775.
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Serwaah, Bonsu Amma. "Comparative retrospective analysis assessment of extracellular volume excess in hypertensive hemodialysis patients." Doctoral diss., University of Central Florida, 2011. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5040.
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Cardiovascular disease, including hypertension, accounts for almost 50% of the deaths in patients with end stage renal disease (ESRD) on hemodialysis (HD) yet hypertension remains very poorly controlled in this population. The purpose of this study was to retrospectively compare control of hypertension in hemodialysis (HD) patients when extracellular volume (ECV) was assessed and managed by clinical parameters and physical assessment data alone with control of hypertension when data from blood volume monitoring (BVM) technology was also used to assess and manage ECV in a freestanding outpatient hemodialysis unit. The main cause of hypertension in the ESRD population has been identified as increased ECV most likely secondary to increased interdialytic weight gain and failure to attain and maintain patient's dry weight. HD nurses often employ clinical parameters along with physical examination to determine a patient's pre, intra, and post dialytic fluid status and this approach can have a high index of error. BVM technology is being used in many hemodialysis units to assist with assessment of ECV. A comparative retrospective chart review was used to collect data for this project. A descriptive, cross-sectional design was employed to answer the question: "Are hypertensive hemodialysis patients who dialyze in a freestanding dialysis unit, where BVM technology is utilized, more likely to be normotensive as defined by a pre dialysis blood pressure of less than 140/90 and post dialysis blood pressure less than 130/80"? A pilot study was conducted to determine if the patient population and data were available in existing patient records for extrapolation. Approval for the study was obtained from the University IRB. A convenience sample was obtained from the records of patients meeting the inclusion criteria.; Variables were measured and analyzed using descriptive statistics such as sampled paired T-test to compare pre and post BVM systolic, diastolic blood pressures, intradialytic weight gain, serum Albumin and sodium levels, and hemoglobin. A p-value of 0.05 was assigned for statistical significance. Data analysis showed there were statisticaly significant differences in the pre dialysis systolic blood pressure, post BVM, and the serum sodium pre and post BVM when the two groups were compared These statistically significant findings support a correlation between reduction in the HD patient's ECV and improved blood pressure control. The reduction of pre-dialysis SBP was significant because many patients on hemodialysis have systolic hypertension that may or may not coexist with diastolic hypertension. The findings of this study may be used to formulate a protocol to be used in the HD units where the BVM is available. The protocol would rely on accurate nursing assessment of clinical parameters, patient verbalizations of symptoms, and the routine use of the BVM in order to continuously assess the patient's fluid status. Future research recommendations include conducting the study in a population closer to the national sample, a study where glucose readings and /or hemoglobin A1C levels are measured to assess the impact of glucose on ECV, and which antihypertensive class of medication works best with BVM technology to effectively manage hypertension in this population.ID: 029808737; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Thesis (D.N.P.)--University of Central Florida, 2011.; Includes bibliographical references (p. 74-81).
D.N.P.
Doctorate
Nursing
Nursing Practice
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Mitra, Sandip. "The pathophysiology of fluid removal during haemodialysis : implications for blood volume monitoring and determination of dry weight." Thesis, University College London (University of London), 2007. http://discovery.ucl.ac.uk/1444890/.
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The aim of the research was to characterise the pathophysiology of ultrafiltration (UF) during haemodialysis (HD) using a range of assessment tools. The hypothesis was that objective monitoring would facilitate accurate estimation of dry weight (DW) and help optimise UF. Measurement timing, white-coat effect, UF prescription and volume status influenced blood pressure (BP) readings, particularly predialysis and immediate post- dialysis measurements. The 20-min post-dialysis BP best reflected interdialytic control. Extracellular volume measurements (ECF) using Bioimpedance spectroscopy (BIS) were reproducible, accurate, and confirmed the tight link between nutritional and volume status. The late increase in ECF and decline in nutritional status as end-stage approached, were only partially corrected by dialysis. Relative blood volume (RBV) characteristics were investigated using short UF pulses (perturbation analysis), at different hydration states, to identify predictors of hypotension and approaching DW. RBV change was greater as predicted DW approached. The critical level of RBV reduction leading to hypotension showed a wide inter-individual variation. The approach to linearity of RBV decay curve was a surrogate for plasma refill (PR) and predicted impending hypotension. The role of heat exchange on cardiovascular stability was also examined. Indocyanine green emerged as a suitable tracer for determining PV repeatedly during HD. The method was employed simultaneously with BIS to demonstrate abnormal proportional compartmental fluid distribution and assess fluid shifts and PR during UF. A significant relationship was demonstrated between ECF change, PR and haemodynamic stability. The dissociation between simultaneous absolute and RBV measurements was explained by a changing Fcell ratio, suggesting significant intravascular shifts within the microcirculation during UF. Objective monitoring has improved understanding of the pathophysiology of UF during HD. However, the main factors limiting fluid removal during HD are patient-specific responses to UF. Individualised prescriptions will require use of systems to characterise patient responses, and prompt appropriate adjustments. These studies may contribute.
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Kennerley, Aneurin James. "Investigation of the haemodynamic response : Æ’MRI techniques with concurrent optical measures of cerebral blood flow or volume." Thesis, University of Sheffield, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.434501.
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Hurton, Lenka. "Reducing post-bleeding mortality of horseshoe crabs (Limulus polyphemus) used in the biomedical industry." Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/36231.
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This study examined the effects of blood extraction on the survival of horseshoe crabs and performed a preliminary investigation into amebocyte maintenance in vitro. Hemolymph volume of L. polyphemus was estimated over a representative size range of adults. Hemolymph volume expressed as a percentage of wet body weight was 25 ± 2.2% (mean ± S.D.) for males and 25 ± 5.1% for females.
Mortality associated with blood extraction was evaluated for horseshoe crabs bled 0, 10, 20, 30, and 40% of their estimated hemolymph volume (unstressed group, N = 200). Mortality associated with the same bleeding levels was evaluated in horseshoe crabs that underwent simulated transport and handling procedures of the biomedical industry's bleeding process (stressed group, N = 195). Mortality rates of the unbled crabs were not significantly different between the stressed group and unstressed group. Of the bled animals, there was a higher (8.3%) mortality rate in the stressed group, than that (0%) in the unstressed group (P < 0.0001). Within the stressed group, mortality was significantly associated with bleeding (P = 0.0088).
Horseshoe crab serum and a variety of standard insect cell culture media were evaluated for their effects on amebocyte morphology and viability after 7 days of maintenance in vitro. Horseshoe crab serum-supplemented cultures had significantly higher cell viability than serum-free cultures (N = 6; P = 0.0147). Significant differences in amebocyte viability were identified among the six insect cell culture media tested (N = 36; P < 0.0001), with the highest amebocyte viability of 77.2 ± 5.1% (mean ± S.D.) in Grace's Insect Medium without serum.
Information gained from this study provides guidance on altering biomedical bleeding protocols to decrease horseshoe crab stress and mortality, and advances information on amebocyte culture medium selection, both of which contribute to decreasing the biomedical industry's impact on the horseshoe crab population.Master of Science
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Evans, John Kenrick. "The effects of oestrogen on renal and systemic haemodynamics in the rat : influence of intrarenal vasoactive substances and plasma volume status." Thesis, Keele University, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.328028.
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Fonseca, Eliana Bonetti. "Comparação da variação da pressão sistólica e de pulso nas ventilações com pressão e volume controlados: estudo experimental em coelhos." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/5/5152/tde-28012007-103110/.
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Introdução: A Variação da Pressão Sistólica (VPS) e da Pressão de Pulso (VPP) têm sido propostas como métodos efetivos para monitoração hemodinâmica, em predizer a resposta à reposição da volemia durante a ventilação mecânica. A primeira é calculada pela diferença entre a pressão sistólica máxima e mínima em um ciclo respiratório, e composta pela somatória dos componentes delta up e delta down; e a VPP obtida pela diferença entre a pressão sistólica e diastólica também em um ciclo respiratório. O objetivo deste estudo foi avaliar a VPS e seus componentes, e a VPP durante a ventilação com volume (VCV) e pressão (PCV) controlados, em coelhos normovolêmicos ou submetidos à hemorragia controlada. Método: Trinta e dois coelhos foram distribuídos de forma aleatória em quatro grupos: G1-ConPCV, G2-HemPCV, G3-ConVCV e G4-HemVCV. Foram ventilados em PCV ou VCV, com volume corrente entre 10 e 12 ml.kg-1 e freqüência respiratória para manter normocapnia. Nos grupos controle (G1-ConPCV e G3-ConVCV), sangue não foi retirado, e cada momento foi avaliado por 30 minutos (M0, M1 e M2); nos grupos com hemorragia (G2-HemPCV e G4-HemVCV), não houve perda sangüínea em M0, em M1 retirou-se 15% da volemia estimada, assim como em M2, de forma gradual. Os dados foram submetidos à análise de variância para medidas repetidas (ANOVA), sendo considerados significativos para um valor de p<0,05, e apresentados na forma de média e desvio-padrão. Resultados: Não houve diferença em M0 entre os grupos estudados. Em M1, os grupos com perda sanguínea apresentaram maiores variações na VPS, em seu componente delta down e na VPP, diferindo significativamente apenas dos grupos controle. Quando a volemia foi reduzida em 30% (M2), G4-HemVCV apresentou maior variação na pressão sistólica, no componente delta down e na pressão de pulso; bem como ambos grupos submetidos à hemorragia apresentaram valores significativamente maiores do que os grupos controle. O débito cardíaco não apresentou variação significativa (p>0,05) entre os momentos e grupos estudados. Conclusões: Em coelhos normovolêmicos ou com hipovolemia leve, ambos modos de ventilação se comportam de forma semelhante sobre as variáveis estudadas, ao passo que na hipovolemia moderada pôde-se observar menor comprometimento hemodinâmico durante a PCVRationale: Systolic pressure variation (SPV) and pulse pressure variation (PPV) indices have been proposed as effective methods of hemodynamic monitoring to predict fluid responsiveness during mechanical ventilation. SPV is calculated by the difference between the maximum and minimum values of systolic blood pressure following a single positive pressure breath, and it is made up of the sum of their components delta up and delta down; PPV is obtained by the difference between systolic and diastolic blood pressure also in a single positive pressure breath. The purpose of this study was to evaluate SPV and its components, and PPV during volume (VCV) and pressure (PCV) controlled ventilation in normovolemic rabbits or ones submitted to graded hemorrhage. Method: Thirty two rabbits were randomly allocated in four groups: G1- ConPCV, G2-HemPCV, G3-ConVCV and G4-HemVCV. They were ventilated in PCV or VCV; tidal volume was fixed between 10 to 12 mL.kg-1 and respiratory rate was monitored in order to maintain normocapnia. In control groups (G1- ConPCV and G3-ConVCV) blood was not withdrawn and each moment was evaluated for 30 minutes (M0, M1 and M2); in hemorrhage groups (G2-HemPCV and G4-HemVCV) there was no blood loss in M0; in M1 and M2 15% of estimated volemia was graded withdrawn. Data were submitted to analysis of variance for repeated measures (ANOVA); significance level was p<0,05 and results were expressed as mean ± standard deviation. Results: In M0, no significant differences were observed among all groups. Hemorrhagic groups (G2-HemPCV and G4-HemVCV) presented higher SPV, delta down and PPV in M1, differing significantly (p<0,05) only from control groups. When 30% of estimated blood volume was removed, higher SPV, delta down and PPV were observed mainly in G4-HemVCV. Cardiac output did not vary significantly (p>0,05) among groups and moments. Conclusions: In rabbits with normovolemia or slight hemorrhage, both modes of ventilation had similar behavior over studied parameters, while in the ones undergoing moderate hemorrhage PCV determined less hemodynamic compromising
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Bizeau, Alexandre. "Segmentation et extraction de caractéristiques des vaisseaux sanguins cérébraux à l'aide de l'IRM." Mémoire, Université de Sherbrooke, 2017. http://hdl.handle.net/11143/10259.
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Le couplage neuro-vasculaire est un domaine grandissant. Ce dernier étudie les effets de l’activité cérébrale sur le comportement du flux sanguin cérébral (cerebral blood flow, CBF) et sur le flux des vaisseaux sanguins. Avec l’aide de l’imagerie par résonance magnétique (IRM), il est possible d’obtenir des images comme les images pondérées par susceptibilité (susceptibility weighted imaging, SWI) pour voir les veines ou bien avec des images de temps de vol par angiographie (time-of-flight magnetic resonance angiography, TOF MRA) pour imager les artères. Ces images permettent d’avoir une représentation structurelle des vaisseaux dans le cerveau.
Ce mémoire présente une méthode permettant la segmentation des vaisseaux sanguins à partir d’images structurelles afin d’en extraire les caractéristiques. En utilisant le masque de segmentation, il est possible de calculer le diamètre des vaisseaux ainsi que leur longueur.
Avec l’aide de tels outils de segmentation automatique, nous avons conduit une étude permettant d’analyser le comportement des vaisseaux sanguins lors d’activités neuronales. Grâce à une stimulation visuelle, nous avons fait l’acquisition de deux images; la première dite au repos et la seconde avec stimulation. Nous avons pu comparer le diamètre dans chacune des images et ainsi obtenir la vasodilatation en millimètre, mais également en pourcentage, et cela pour chaque voxel. Nous avons également calculé la distance entre le site d’activation et un voxel pour observer l’amplitude de la vasodilatation en fonction de la distance.
Tout ceci permet d’avoir une meilleure compréhension du système vasculaire du cerveau humain.Abstract : The neurovascular coupling is a growing field; it studies the effects of cerebral activity on the behaviour of cerebral blood flow (CBF) and the blood vessels themselves. With the help of magnetic resonance imaging (MRI), it is possible to obtain images such as susceptibility weighted imaging (SWI) to see the veins or time-of-flight magnetic resonance angiography (TOF MRA) to visualize the arteries. These images allow having a structural representation of vessels in the brain. This thesis presents a method to segment blood vessels from structural images and extract their features. Using the segmentation mask, it is possible to calculate the diameter of the vessels as well as their length. With the help of such automatic segmentation tools, we conducted a study to analyze the behaviour of blood vessels during neuronal activities. Due to visual stimulation, we have acquired two images; one at rest and the other with stimulation. We compare the diameter in each of the images and obtain vasodilation in millimeters, but also as a percentage in each voxel. We also calculated the distance between the activation site and each voxel to see the magnitude of the vasodilation function of the distance. All this provides a better understanding of the vascular system of the human brain.
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Chae, Sungwon. "Acute Endocrine Responses to Rest Redistribution with Heavier Loads in Resistance-Trained Men." Thesis, University of North Texas, 2020. https://digital.library.unt.edu/ark:/67531/metadc1707275/.
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The purpose of this study was to investigate endocrine responses to redistribution with heavier loads (RR+L) during back squat (BS) exercise in resistance-trained men. Ten men (mean±SE; 23±2 years, 175.6±2.0 cm, 78.0±3.4 kg, 4±1 training years) were assigned using randomization to either RR+L (4 sets of (2×5 repetitions) of BS with 30 s intra-set and 90 s inter-set rest using 75% of their 1RM) or traditional sets (TS; 4 sets of 10 repetitions of BS with 120 s inter-set rest using 70% of their 1RM). Fasted blood samples were collected pre-exercise (PRE), immediately post-exercise (IP), and 5 (+5), 15 (+15), and 30 (+30) minutes post-exercise to analyze the concentrations of testosterone (T), growth hormone (GH), cortisol (C), and blood lactate (BL). Two-way ANOVAs with repeated measures were used (p≤0.05). A main effect of condition (p=0.023) was observed for BL (RR+L; 5.9±0.5 vs TS; 6.7±0.4 mmol/L). A main effect of time point (p≤0.001) was observed for T, GH, C, and BL. T was greater at IP (8.8±1.1), +5 (9.0±1.1), +15 (8.5±1.0), and +30 (8.0±1.0) than PRE (7.1±0.8 ng/mL). GH was greater at IP (58.3±12.7), +5 (62.8±12.7), +15 (67.9±13.3), and +30 (52.8±11.2) than PRE (3.6±1.6 µIU/mL). C was greater at +15 (25.5±2.9) and +30 (25.6±2.7) than PRE (20.0±2.7 µg/dL). BL was greater at IP (8.6±0.6), +5 (8.2±0.6), +15 (7.4±0.5), and +30 (5.8±0.5) than PRE (1.4±0.2 mmol/L). RR+L resulted in lower BL but no differences in T, GH, and C responses compared to TS. Thus, practitioners may incorporate RR+L without affecting endocrine responses.
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Kimmel, Peter Blair. "The significance of hypovolemia in dehydrational death in anurans." PDXScholar, 1985. https://pdxscholar.library.pdx.edu/open_access_etds/3432.
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The importance of hypovolemia in dehydrational death was assessed in two anuran species. Xenopus laeyis, a species which experiences a significant reduction in circulating plasma volume with dehydration, was used to evaluate the role of sympathetic reflex compensation in hypovolemia. Adrenergic blockade with propranolol or phenoxybenzamine produced no significant reduction in dehydration tolerance in this species, although β-blockade with propranolol appeared to have a minor effect. The role of hypovolemic shock in the terminal circulatory collapse that precedes death in dehydrating anurans was investigated in the toad, Bufo marinus. The activity of lysosomal proteinases (cathepsins) was used as an indicator of the shock state. An assay was developed for the determination of cathepsin activity in toad plasma and was used to demonstrate the presence of proteinases similar in pH dependence to mammalian cathepsins Bl and D. Plasma cathepsin D-type activity increased with dehydration in toads but was not significantly different from the activity in controls or in toads subjected to splanchnic artery occlusion. Toads appear to maintain plasma volume to 20% water loss at the expense of other extracellular fluids. These results do not support the hypothesis that hypovolemia is a direct cause of dehydrational death in anurans.
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Baustian, Mark. "The contribution of the lymph hearts in compensation for acute hypovolemic stress in the toad Bufo marinus." PDXScholar, 1986. https://pdxscholar.library.pdx.edu/open_access_etds/3517.
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Currently published data on the role of the lymphatic system in amphibians are inadequate and contradictory. Estimates of the rate of formation of lymph and the role of the lymph hearts in returning this fluid to the circulation are not based on actual volume determinations but rather estimates derived from changes in hematocrit using published values of plasma and blood volume. The lymph hearts are known to be vital to the maintenance of normal fluid compartment physiology and to increase their rate of activity during episodes of hypovolemic stress. Yet, significant redistribution of body fluids following hemorrage appears to occur in animals without lymph hearts.
In this study, plasma and blood volumes were determined by the dye dilution technique using injected Evan's blue dye to label the plasma. Eight intact and 6 animals with their lymph hearts destroyed were hemorrhaged to 78% and 75% of their initial blood volumes, respectively. Changes in blood volume were measured following the hemorrhage by analysis of Evan's blue washout and hemodilution.
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Celeita-Rodríguez, Nathalia. "Comparação entre índices dinâmicos e volumétricos de pré-carga em cães submetidos à hemorragia moderada seguida de reposição volêmica." Botucatu, 2016. http://hdl.handle.net/11449/135860.
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Orientador: Francisco José Teixeira NetoResumo: Objetivo: Avaliar os efeitos da perda moderada de sangue seguida por reposição volêmica (RV) no índice de volume sanguíneo intratorácico (ITBVI), índice do volume global diastólico final (GEDVI), variação da pressão de pulso (VPP) e variação do volume sistólico (VVS).Delineamento experimental: Estudo prospectivo aleatorizado.Animais: Sete cães da raça Pointer Inglês (20 a 31,2 kg).Métodos: A anestesia foi mantida com sevofluorano sob ventilação mecânica no modo volume controlado com bloqueio neuromuscular induzido pelo atracúrio. A concentração expirada de sevofluorano (ETsevo), foi ajustada de forma a inibir alterações na frequência cardíaca e na pressão arterial média (PAM) em resposta à estimulação nociceptiva (< 20% mudança relativa). As variáveis estudadas foram registradas no momento basal, após retirada de 14 a 16 mL/kg da volemia e após a RV com sangue autólogo. Resultados: A anestesia foi mantida com 3,1 ± 0,3% de ETsevo. Um animal discrepante (“outlier”) não foi incluído da análise estatística. A hemorragia diminuiu significativamente (P < 0,05) o índice cardíaco (IC), índice sistólico (IS) e PAM em 20-25% dos valores basais (variações percentuais nos valores médios). A RV aumentou significativamente a PAM em relação aos valores registrados após hemorragia (31% de aumento); enquanto o IC e IS elevaram-se significativamente após a RV (29-30% acima dos valores basais). Após a hemorragia, o ITBVI e GEDVI se reduziram significativamente em 15% em relação aos val... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Objective: To evaluate the effects moderate blood loss followed by volume replacement (VR) on intra-thoracic blood volume index (ITBVI), global end-diastolic volume index (GEDVI), pulse pressure variation (PPV), and stroke volume variation (SVV).Study design: Prospective, randomized study.Animals: Seven English Pointer dogs (20.0–31.2 kg).Methods: Anesthesia was maintained with sevoflurane under volume-controlled ventilation and atracurium induced neuromuscular blockade. End-expired sevoflurane (ETsevo) concentrations were adjusted to inhibit heart rate and mean arterial blood pressure (MAP) changes in response to nociceptive stimulation (< 20% relative change). Data recorded at baseline, after withdrawal of 14–16 mL kg-1 of blood volume and after VR with autologous blood.Results: Anesthesia was maintained with 3.1 ± 0.3 vol% of ETsevo concentrations. One outlier was excluded from the statistical analysis. Hemorrhage significantly (P < 0.05) decreased cardiac index (CI), stroke index (SI), and MAP by 20–25% from baseline (percent changes in mean values). Volume replacement significantly increased MAP in comparison to values recorded after hemorrhage (31% increase); while CI and SI were significantly increased after VR in comparison hemorrhage and to baseline (29–30% above baseline). The ITBVI and GEDVI were decreased by 15% from baseline after blood loss; while VR significantly increased ITBVI and GEDVI by 21% from values recorded after hemorrhage. Relat... (Complete abstract click electronic access below)
Mestre
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Naber, Ady [Verfasser], and W. [Akademischer Betreuer] Nahm. "Intraoperative, Quantitative, and Non-Contact Blood Volume Flow Measurement via Indocyanine Green Fluorescence Angiography / Ady Naber ; Betreuer: W. Nahm." Karlsruhe : KIT-Bibliothek, 2021. http://d-nb.info/123918056X/34.
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Vaeth, Albert. "Imagerie du volume sanguin cérébral : applications." Université Joseph Fourier (Grenoble), 1998. http://www.theses.fr/1998GRE10205.
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Ce travail est centre sur l'evaluation et l'optimisation d'une methode d'imagerie du volume sanguin cerebral (vsc) par resonance magnetique nucleaire (rmn). La methode est basee sur la mesure des variations du temps caracteristiques, t#2*, de decroissance du signal de precession libre, lors de l'injection intraveineuse d'un produit de contraste de forte susceptibilite magnetique et dont la duree de vie dans le secteur sanguin est longue. Le travail a porte plus particulierement porte sur l'evaluation des conditions experimentales qui permettent d'observer une relation lineaire entre les variations r#2* de la vitesse de relaxation r#2* = 1/t#2* et le volume sanguin cerebral. La decroissance du signal rmn des protons associee aux inhomogeneites du champ magnetique dans le tissu cerebral est etudiee a l'aide de simulations de type monte carlo. L'influence des differents facteurs sur la variation de la vitesse de relaxation transversale r#2* lors de l'injection est analysee : taille des vaisseaux, dose de produit de contraste, temps d'echo, technique de r#2*. L'influence de la methode utilisee pour la mesure du parametre r#2* est etudiee dans le detail. L'interet des methodes d'echo de gradient multiples est souligne. Il est montre que ces methodes sont susceptibles de fournir une cartographie quantitative du vsc relatif (voire absolu) avec une haute resolution spatiale et un excellent rapport signal sur bruit. La methode est evaluee sur un modele experimental (rat) et les differentes sources d'erreurs susceptibles d'affecter la determination du vsc sont examinees. La methode de mesure est appliquee a l'evaluation du lien entre le vsc et les conditions physiologiques et pathologiques chez le rat (variation de la pression partielle en co#2, clampage unilateral de la carotide gauche).