scholarly journals Using a Human Circulation Mathematical Model to Simulate the Effects of Hemodialysis and Therapeutic Hypothermia

2021 ◽  
Vol 12 (1) ◽  
pp. 307
Author(s):  
Jermiah J. Joseph ◽  
Timothy J. Hunter ◽  
Clara Sun ◽  
Daniel Goldman ◽  
Sanjay R. Kharche ◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
Blood Pressure ◽  
Mathematical Model ◽  
Heart Rate ◽  
Renal Failure ◽  
Shear Stress ◽  
Wall Shear Stress ◽  
Therapeutic Hypothermia ◽  
Large Vessel ◽  
Wall Shear

Background: We developed a hemodynamic mathematical model of human circulation coupled to a virtual hemodialyzer. The model was used to explore mechanisms underlying our clinical observations involving hemodialysis. Methods: The model consists of whole body human circulation, baroreflex feedback control, and a hemodialyzer. Four model populations encompassing baseline, dialysed, therapeutic hypothermia treated, and simultaneous dialysed with hypothermia were generated. In all populations atrial fibrillation and renal failure as co-morbidities, and exercise as a treatment were simulated. Clinically relevant measurables were used to quantify the effects of each in silico experiment. Sensitivity analysis was used to uncover the most relevant parameters. Results: Relative to baseline, the modelled dialysis increased the population mean diastolic blood pressure by 5%, large vessel wall shear stress by 6%, and heart rate by 20%. Therapeutic hypothermia increased systolic blood pressure by 3%, reduced large vessel shear stress by 15%, and did not affect heart rate. Therapeutic hypothermia reduced wall shear stress by 15% in the aorta and 6% in the kidneys, suggesting a potential anti-inflammatory benefit. Therapeutic hypothermia reduced cardiac output under atrial fibrillation by 12% and under renal failure by 20%. Therapeutic hypothermia and exercise did not affect dialyser function, but increased water removal by approximately 40%. Conclusions: This study illuminates some mechanisms of the action of therapeutic hypothermia. It also suggests clinical measurables that may be used as surrogates to diagnose underlying diseases such as atrial fibrillation.

scholarly journals Using a Human Circulation Mathematical Model to Simulate the Effects of Hemodialysis and Therapeutic Hypothermia

2021 ◽  
Author(s):  
Jermiah J. Joseph ◽  
Timothy J. Hunter ◽  
Clara Sun ◽  
Daniel Goldman ◽  
Sanjay R. Kharche ◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
Blood Pressure ◽  
Mathematical Model ◽  
Heart Rate ◽  
Renal Failure ◽  
Blood Flow ◽  
Standard Deviation ◽  
Therapeutic Hypothermia ◽  
Whole Body ◽  
Baroreflex Control

AbstractBackgroundThe human blood circulation is an intricate process regulated by multiple biophysical factors. Our patients often suffer from renal disease and atrial fibrillation, and are given treatments such as therapeutic hypothermia, exercise, and hemodialysis. In this work, a hemodynamic mathematical model of human circulation coupled to a representative dialysis machine is developed and used to explore causal mechanisms of our recent clinical observations.MethodsAn ordinary differential equation model consisting of human whole body circulation, baroreflex control, and a hemodialysis machine was implemented. Experimentally informed parameter alterations were used to implement hemodialysis and therapeutic hypothermia. By means of parameter perturbation, four model populations encompassing baseline, dialysed, hypothermia treated, and simultaneous dialysed with hypothermia were generated. In model populations, multiple conditions including atrial fibrillation, exercise, and renal failure were simulated. The effects of all conditions on clinically relevant non-invasive measurables such as heart rate and blood pressure were quantified. A parameter sensitivity analysis was implemented to rank model output influencing parameters in the presented model.ResultsResults were interpreted as alterations of the respective populations mean values and standard deviations of the clinical measurables, both in relation to the baseline population. A clinical measurable’s smaller standard deviation (in comparison to baseline population) was interpreted as a stronger association between a given clinical measure and the corresponding underlying process, which may permit the use of deducing one by observation of the other.The modelled dialysis was observed to increase systolic blood pressure, vessel shear, and heart rate. Therapeutic hypothermia was observed to reduce blood pressure as well as the intra-population standard deviation (heterogeneity) of blood flow in the large (aorta) and small (kidney) vasculature. Therapeutic hypothermia reduced shear in vessels, suggesting a potential benefit with respect to endothelial dysfunction and maintenance of microcirculatory blood flow. The action of therapeutic hypothermia under conditions such as atrial fibrillation, exercise, and renal failure was to reduce total blood flow, which was applicable in all simulated populations. Therapeutic hypothermia did not affect the dialysis function, but exercise improved the efficacy of dialysis by facilitating water removal.ConclusionsThis study illuminates some mechanisms of action for therapeutic hypothermia. It also suggests clinical measurables that may be used as surrogates to diagnose underlying diseases such as atrial fibrillation.

A New Ultrasonographic Instrument for Measuring Vessel Wall Shear Stress: Comparison to a Mathematical Model in Essential Hypertensives

1996 ◽  
pp. 403-407 ◽  
Author(s):  
Moreno Bardelli ◽  
Renzo Carretta ◽  
Domenico Dotti ◽  
Bruno Fabris ◽  
Fabio Fischetti ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Shear Stress ◽  
Wall Shear Stress ◽  
Vessel Wall ◽  
Measuring Vessel ◽  
Wall Shear

Study on Velocity Distribution Estimation Using Blood Pressure Data Based on the Coupled Wave Theory of Elastic Pipes and Fluids

2019 ◽  
Author(s):  
Takeshi Tokunaga ◽  
Koji Mori ◽  
Hiroko Kadowaki ◽  
Takashi Saito
Keyword(s):  
Blood Pressure ◽  
Shear Stress ◽  
Endothelial Cell ◽  
Wall Shear Stress ◽  
Cell Function ◽  
Wave Theory ◽  
Pressure Data ◽  
Endothelial Cell Function ◽  
Blood Pressure Data ◽  
Wall Shear

Abstract Cardiovascular disease that is one of Non-Communicable Disease accounts for about 25% of death in Japan. Prevention of arteriosclerosis that is a main cause of cardiovascular disease is important. Since an early lesions of arteriosclerosis progress as functional change of an endothelial cell that is uniformly distributed on the luminal surface of a blood vessel, an accurate evaluation of the endothelial cell function is important as prevention of the arteriosclerosis. Although Flow-Mediated Dilation (FMD) is widely used as a diagnosis of the endothelial cell function in clinic, it is an evaluation method that uses a static diameter of a blood vessel. Moreover, it isn’t possible to take into account individual difference of a wall shear stress on the endothelial cell. In previous study, it is found that an evoked hyperemic wall shear stress is a major correlate of %FMD. In order to accurately measure the endothelial cell function, it is necessary to simply assess the hyperemic shear stress during FMD. However, it is difficult to non-invasively measure the hyperemic shear stress on the endothelial cell in clinic. In this study, we focused on a blood pressure data that is obtained non-invasively and formulated a relationship between the pressure and a flow velocity based on the coupled wave theory. And we estimated a hyperemic shear stress by using a blood pressure data that is obtained by a tonometry method in experiment that simulate FMD. As a result of estimating the hyperemic shear stress, it reflected characteristics of blood flow in clinic. It may be necessary to consider the hyperemic pressure fluctuation that is waves including low frequency components. Moreover, the hyperemic pressure fluctuation should not be treated as a waveform that has individually different a static pressure in estimation of the hyperemic wall shear stress.

Numerical Simulation of Flow-Induced Wall Shear Stress of a One Strand Tundish Design

2011 ◽  
Vol 402 ◽  
pp. 85-89 ◽  
Author(s):  
Zhi Bing Tian ◽  
Yan Jin ◽  
Hong Yu Li
Keyword(s):  
Numerical Simulation ◽  
Mathematical Model ◽  
Shear Stress ◽  
Service Life ◽  
Wall Shear Stress ◽  
Design Parameters ◽  
Horizontal Distance ◽  
Wall Shear

In this paper, the flow-induced wall shear stress on the wall of a one Strand tundish has been computed by a 3-D mathematical model. Different design parameters of the tundish such as HB(the height of the dam) and DB(the horizontal distance between the dam and the outlet of the tundish) are studied by analyzing the flow-induced wall shear stress. After a series of calculation, A modification in design parameters (DB and HB )of the tundish can reduce the wall shear stress, thus may help to improve the service life of the tundish.

Numerical Simulation of Blood Flow Through Stenosed Vessel

2004 ◽  
Author(s):  
Kimie Onogi ◽  
Kazuhiro Kohge ◽  
Kiyoshi Minemura
Keyword(s):  
Heart Rate ◽  
Blood Flow ◽  
Shear Stress ◽  
Wall Shear Stress ◽  
Flow Behavior ◽  
Pressure Change ◽  
Sinusoidal Waveform ◽  
Stenosed Vessel ◽  
Flow Through ◽  
Wall Shear

This article illustrates numerical results on pulsating blood flow through moderately stenosed blood vessel. Two kinds of waveform, that is, a purely sinusoidal waveform and a non-sinusoidal one just like human blood flow are calculated for two cases of heart rate as 60 and 160 (1/s), and resultant flow behavior such as flow velocities, secondary flow, wall shear stress and pressure change are discussed. The abrupt changes in the pressure and wall shear stress occur on the throat of the stenosis, suggesting that this part is easily damaged by the effects when the heart rate is increased.

Blood Flow Manipulation in the Aorta With Coarctation and Arch Narrowing for Pediatric Subjects

2020 ◽  
Vol 88 (2) ◽  
Author(s):  
Yuxi Jia ◽  
Kumaradevan Punithakumar ◽  
Michelle Noga ◽  
Arman Hemmati
Keyword(s):  
Blood Pressure ◽  
Blood Flow ◽  
Shear Stress ◽  
Wall Shear Stress ◽  
Aortic Arch ◽  
Flow Direction ◽  
Upper Body ◽  
Patient Specific ◽  
Shear Stresses ◽  
Wall Shear

Abstract The characteristics of blood flow in an abnormal pediatric aorta with an aortic coarctation and aortic arch narrowing are examined using direct numerical simulations and patient-specific boundary conditions. The blood flow simulations of a normal pediatric aorta are used for comparison to identify unique flow features resulting from the aorta geometrical anomalies. Despite flow similarities compared to the flow in normal aortic arch, the flow velocity decreases with an increase in pressure, wall shear stress, and vorticity around both anomalies. The presence of wall shear stresses in the trailing indentation region and aorta coarctation opposing the primary flow direction suggests that there exist recirculation zones in the aorta. The discrepancy in relative flowrates through the top and bottom of the aorta outlets, and the pressure drop across the coarctation, implies a high blood pressure in the upper body and a low blood pressure in the lower body. We propose using flow manipulators prior to the aortic arch and coarctation to lower the wall shear stress, while making the recirculation regions both smaller and weaker. The flow manipulators form a guide to divert and correct blood flow in critical regions of the aorta with anomalies.

Negative Correlation of Wall Thickness With Wall Blood Pressure in a Patient-Specific Atherosclerotic Coronary Artery: A Case Report

2012 ◽  
Author(s):  
Biyue Liu ◽  
Jie Zheng ◽  
Richard Bach ◽  
Dalin Tang
Keyword(s):  
Blood Pressure ◽  
Shear Stress ◽  
Wall Shear Stress ◽  
Wall Thickness ◽  
Patient Specific ◽  
Artery Wall ◽  
Atherosclerosis Progression ◽  
Wall Shear ◽  
Intensive Investigation ◽  
The Impact

There are two major hemodynamic stresses imposed at the blood-arterial wall interface by flowing blood: the wall shear stress (WSS) acting tangentially to the wall, and the wall pressure (WP) acting vertically to the wall. These forces influence the artery wall metabolism and correspond to the local modifications of artery wall thickness, composition, microarchitecture, and compliance [2]. The role of flow wall shear stress in atherosclerosis progression has been under intensive investigation [4], while the impact of local blood pressure on plaque progression has been under-studied.

A Microfluidic System for Precisely Reproducing Physiological Blood Pressure and Wall Shear Stress to Endothelial Cells

The Analyst ◽  
2021 ◽  
Author(s):  
Jingtong Na ◽  
Siyu Hu ◽  
Chundong Xue ◽  
Yanxia Wang ◽  
Kejie Chen ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Endothelial Cells ◽  
Shear Stress ◽  
Wall Shear Stress ◽  
Endothelial Function ◽  
Microfluidic System ◽  
Hemodynamic Stress ◽  
Wall Shear ◽  
Quantitative Impact

To reproduce hemodynamic stress microenvironments of endothelial cells in vitro is of vital significance, by which one could exploit quantitative impact of hemodynamic stresses on endothelial function and seek innovative...

Analysis of complex flow and the relationship between blood pressure, wall shear stress, and intima-media thickness in the human carotid artery

2007 ◽  
Vol 293 (2) ◽  
pp. H1031-H1037 ◽  
Author(s):  
A. D. Augst ◽  
B. Ariff ◽  
S. A. G. McG. Thom ◽  
X. Y. Xu ◽  
A. D. Hughes
Keyword(s):  
Blood Pressure ◽  
Shear Stress ◽  
Carotid Artery ◽  
Wall Shear Stress ◽  
Healthy Subjects ◽  
Systolic Pressure ◽  
Intima Media Thickness ◽  
Complex Flow ◽  
Media Thickness ◽  
Wall Shear

Background: Previous clinical studies have observed relationships between increased intima-media thickness (IMT) in the carotid artery, elevated blood pressure, and low wall shear stress (WSS) calculated from the Poiseuille equation. This study used numerical methods to more accurately determine WSS in the carotid artery and to investigate possible determinants of increased IMT. Methods: IMT [common carotid artery (CCA) and bulb], CCA flow velocity, brachial systolic (SBP) and diastolic blood pressure (DBP), and carotid systolic pressure (cSBP) were measured in 14 healthy subjects (aged 44 ± 16 yr). Flow patterns in the carotid bifurcation were determined by computational fluid dynamics (CFD) based on three-dimensional ultrasound geometry. Instantaneous and time-averaged wall shear stress (WSSav), oscillatory shear index (OSI), and wall shear stress angle gradients (WSSAG) were calculated. Results: IMT was positively related to SBP, DBP, cSBP, and WSSAG and inversely related to WSSav in the CCA. In the bulb, IMT was positively related to SBP and cSBP but was not significantly related to WSSav or WSSAG. IMT was unrelated to OSI in both the CCA and the bulb. Conclusion: Increased carotid artery IMT in healthy subjects with no evidence of focal plaques is primarily a response to elevated pressure.

FLOW OF MICROPOLAR FLUID THROUGH CATHETERIZED ARTERY — A MATHEMATICAL MODEL

2012 ◽  
Vol 05 (02) ◽  
pp. 1250019 ◽  
Author(s):  
D. SRINIVASACHARYA ◽  
D. SRIKANTH
Keyword(s):  
Mathematical Model ◽  
Shear Stress ◽  
Wall Shear Stress ◽  
Micropolar Fluid ◽  
Outer Wall ◽  
Shear Stresses ◽  
Closed Form Solutions ◽  
Catheterized Artery ◽  
Wall Shear ◽  
Coupling Number

In this paper, the flow of blood through catheterized artery with mild constriction at the outer wall is considered. The closed form solutions are obtained for velocity and microrotation components. The impedance (resistance to the flow) and wall shear stress are calculated. The effects of catheterization, coupling number, micropolar parameter, and height of the stenosis on impedance and wall shear stresses are discussed.

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