Transient Temperature Profiles in Tissues With Nonuniform Blood Flow Distributions

1982 ◽  
Vol 104 (3) ◽  
pp. 202-208 ◽  
Author(s):  
A. B. Elkowitz ◽  
A. Shitzer ◽  
R. C. Eberhart
Keyword(s):  
Heat Transfer ◽  
Blood Flow ◽  
Steady State ◽  
Flow Distribution ◽  
Tissue Blood Flow ◽  
Transient Temperature ◽  
Temperature Profiles ◽  
Heat Transfer Equation ◽  
Blood Flow Distribution ◽  
Steady State Temperature

Numerical methods and the bio-heat transfer equation are employed to calculate temperature profiles in tissues subjected to nonuniform blood flow distributions, for initial and boundary conditions which simulate experimental physiological situations. Results indicate that one can infer, from sudden changes in temperature distribution, the occurrence of sudden changes in tissue blood flow. However, prediction of blood flow distribution from near equilibrium or steady-state temperature profiles is of poor resolution, and does not appear useful as a practical technique. The methods and results are useful for predictions of temperature profiles in the absence of significant endogenous or exogenous heating; they can be extended to such applications by straightforward methods.

Regional blood flow distribution during the Cushing response: alterations with adrenergic blockade

1985 ◽  
Vol 248 (1) ◽  
pp. H98-H108
Author(s):  
D. G. van Wylen ◽  
L. G. D'Alecy
Keyword(s):  
Blood Flow ◽  
Cardiac Output ◽  
Regional Blood Flow ◽  
Flow Distribution ◽  
Peripheral Tissue ◽  
Systemic Hypertension ◽  
Tissue Blood Flow ◽  
Blood Flow Distribution ◽  
Beta Receptor ◽  
Cushing Response

Regional blood flow distribution (microspheres) and cardiac output (CO, thermal dilution) were measured during the Cushing response in unblocked (UB), beta-receptor-blocked (BB, 2 mg/kg propranolol iv), or alpha-receptor blocked (AB, 0.5 mg/kg + 0.5 mg X kg-1 X min-1 phentolamine iv) chloralose-anesthetized dogs. Intracranial pressure was increased to 150 mmHg by infusion of temperature-controlled artificial cerebrospinal fluid into the cisterna magna. Similar increases in mean arterial pressure were seen in UB and BB, but in AB a Cushing response could not be sustained. In UB, cerebral blood flow (CBF) decreased 50%, coronary blood flow (CoBF) increased 120%, and peripheral tissue blood flow was reduced only in the kidneys (18%) and the intestines (small 22%, large 35%). Blood flow to the other viscera, skin, and skeletal muscle was unchanged. CO (16%) and heart rate (HR, 38%) decreased, and total peripheral resistance (TPR, 68%) and stroke volume (SV, 38%) increased. In BB, CBF decreased 50%, CoBF decreased 20%, and blood flow was reduced 40-80% in all peripheral tissues. CO (69%) and HR (62%) decreased, TPR increased 366%, and SV was unchanged. We conclude that the Cushing response in UB animals combines an alpha-receptor-mediated vasoconstriction with a beta-receptor cardiac stimulation. The beta-mechanism is neither necessary nor sufficient for the hypertension. However, the combination of alpha- and beta-adrenergic mechanisms maintains cardiac output and peripheral tissue blood flow relatively constant while producing a systemic hypertension.

scholarly journals Blood flow distribution in submerged and surface-swimming ducks

1992 ◽  
Vol 166 (1) ◽  
pp. 285-296
Author(s):  
R. Stephenson ◽  
D. R. Jones
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Blood Flow ◽  
Water Surface ◽  
Imaging Technique ◽  
Flow Distribution ◽  
Tissue Blood Flow ◽  
Blood Flow Distribution ◽  
Radiological Imaging ◽  
Aythya Americana

Observations that the response of the avian heart rate to submergence varies under different circumstances have led to speculation about variability of blood flow distribution during voluntary dives. We used a radiological imaging technique to examine the patterns of circulating blood flow in captive redhead ducks (Aythya americana) during rest, swimming, escape dives, forced dives and trapped escape dives and have shown that blood flow distribution in escape dives was the same as that in ducks swimming at the water surface. The response during trapped escape dives, however, was highly variable. Blood pressure was unchanged from the resting value during all activities. Predictions made about blood flow distribution during unrestrained dives on the basis of heart rate and other indirect data were confirmed in this study. However, the trapped escape dive responses indicated that heart rate alone is not always a reliable indicator of tissue blood flow in exercising ducks.

Thermodynamic technique for the quantification of regional blood flow

1980 ◽  
Vol 238 (5) ◽  
pp. H682-H696
Author(s):  
T. Adams ◽  
S. R. Heisey ◽  
M. C. Smith ◽  
M. A. Steinmetz ◽  
J. C. Hartman ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Thermal Analysis ◽  
Blood Flow ◽  
Steady State ◽  
Regional Blood Flow ◽  
Local Blood Flow ◽  
Metabolic Heat ◽  
Steady State Temperature ◽  
Thermal Steady State

A method is described to quantify regional blood flow by thermal analysis. A weak temperature field is established in a tissue and for a thermal steady state, unidirectional heat flux and the associated temperature gradient are measured simultaneously across a small fixed segment of the tissue. This information is evaluated with probe calibrations for homogeneous isotropic fluids, with data from ancillary measurements in the nonperfused tissue and with values of specific heat and density of blood to express local blood flow in heat transfer [effective thermal conductivity (W. degrees C-1 . cm-1 x 10(-3) and/or in perfusion (ml . min-1 . cm-3)] terms. The technique measures local perfusion in small tissue volumes and is usable in acute or chronic experiments. Its accuracy is not a function of the absolute steady-state temperature of the tissue or of its metabolic heat production.

Hemodynamic Effects And Changes Of Blood Flow Distribution By Dextran 70, Dihydroergotamin (DHE) And Their Combination

1981 ◽  
Author(s):  
B Lindblad ◽  
D Bergqviat
Keyword(s):  
Blood Flow ◽  
Cardiac Output ◽  
Femoral Vein ◽  
Venous Pressure ◽  
Flow Distribution ◽  
Tissue Blood Flow ◽  
Blood Flow Distribution ◽  
Arterial Blood ◽  
Dextran 70 ◽  
The Central Nervous System

Dextran 70 and DHE are both effective in reducing the risk for postoperative thromboembolic complications. As they at least in part have different mechanisms of action it is important to analyse if their combination potentiates the prophylactic effect. Therefore it is necessary to study the effect on hemodynamics and tissue blood flow, a problem which is delt with in this report.MATERIAL AND METHODS: In 18 dogs the following parameters were followed: cardiac output, heart rate, arterial blood pressure, central venous pressure, pulmonary artery pressure, left atrium pressure and volume blood flow in the femoral vein. Blood flow distribution was determined by the radioactive microsphere technique.RESULTS: Dextran 70 gave an increase of cardiac output and femoral vein flow. Other hemodynamic parameters were mainly unaffected. Total peripheral resistance decreased. DHE increased arterial blood pressure, central venous pressure and pulmonary arterial pressure. Cardiac output and femoral vein flow were unchanged.Tissue blood flow increased in general slightly after infusion of dextran 70. No significant change in blood flow distribution was seen. DHE reduced pancreatic and thyroid blood flow and increased tissue blood flow to the central nervous system. The blood flow to other organs including the heart was unaffected. The combination of dextran 70 and DHE influenced hemodynamic parameters and flow distribution in an additative way.CONCLUSIONS: From this experimental study it is concluded that it is possible to combine dextran and DHE without inducing a circulatory overload. DHE increased tissue blood flow to the central nervous system.

The effects of inspiratory intrathoracic pressure production on the cardiovascular response to submaximal exercise in health and chronic heart failure

2007 ◽  
Vol 292 (1) ◽  
pp. H580-H592 ◽  
Author(s):  
Jordan D. Miller ◽  
Curtis A. Smith ◽  
Sarah J. Hemauer ◽  
Jerome A. Dempsey
Keyword(s):  
Heart Failure ◽  
Blood Flow ◽  
Cardiac Output ◽  
Steady State ◽  
Chronic Heart Failure ◽  
Flow Distribution ◽  
Submaximal Exercise ◽  
Positive Pressure ◽  
Blood Flow Distribution ◽  
Limb Blood Flow

We sought to determine whether the normal inspiratory intrathoracic pressures (PITP) produced during exercise contribute to the blunted cardiac output and locomotor limb blood flow responses observed in chronic heart failure (CHF). Five chronically instrumented dogs exercised on a treadmill at 2.5 mile/h at 5% grade while healthy or after the induction of tachycardia-induced CHF. We observed several key differences in the cardiovascular responses to changes in the inspiratory PITP excursion between health and CHF; namely, 1) removing ∼70% of the normally produced inspiratory PITP excursion during exercise (with 15 cmH2O inspiratory positive pressure ventilation) significantly reduced stroke volume (SV) in healthy animals by 5 ± 2% ( P < 0.05) but significantly increased SV and cardiac output (QTOT) in animals with CHF by 5 ± 1% ( P < 0.05); 2) doubling the magnitude of the inspiratory PITP excursion had no effect on SV or QTOT in healthy animals but significantly reduced steady-state QTOT and SV in animals with CHF by −4 ± 3% and −10 ± 3%, respectively; 3) removing the majority of the normally produced inspiratory PITP excursion had no effect on blood flow distribution in healthy animals but increased hindlimb blood flow (9 ± 3%, P < 0.05) out of proportion to the increases in QTOT; and 4) the only similarity between healthy and CHF animals was that increasing the inspiratory PITP excursion significantly reduced steady-state locomotor limb blood flow by 5 ± 2% and 6 ± 3%, respectively ( P < 0.05 for both). We conclude that 1) the normally produced inspiratory PITP excursions are required for a maximal SV response to submaximal exercise in healthy animals but detrimental to the SV and QTOT responses to submaximal exercise in CHF, 2) the respiratory muscle ergoreflex tonically restrains locomotor limb blood flow during submaximal exercise in CHF, and 3) excessive inspiratory muscle work further compromises cardiac function and blood flow distribution in both health and CHF.

scholarly journals Noncontact 3-D Speckle Contrast Diffuse Correlation Tomography of Tissue Blood Flow Distribution

2017 ◽  
Vol 36 (10) ◽  
pp. 2068-2076 ◽  
Author(s):  
Chong Huang ◽  
Daniel Irwin ◽  
Mingjun Zhao ◽  
Yu Shang ◽  
Nneamaka Agochukwu ◽  
...  
Keyword(s):  
Blood Flow ◽  
Flow Distribution ◽  
Tissue Blood Flow ◽  
Blood Flow Distribution ◽  
Speckle Contrast

Numerical Analysis of the VAD Outflow Cannula Positioning on the Blood Flow in the Patient–Specific Brain Supplying Arteries

2020 ◽  
Vol 22 (2) ◽  
pp. 619-636 ◽  
Author(s):  
Zbigniew Tyfa ◽  
Damian Obidowski ◽  
Krzysztof Jóźwik
Keyword(s):  
Blood Flow ◽  
Computer Aided Design ◽  
Volume Flow Rate ◽  
Flow Distribution ◽  
Primary Objective ◽  
Patient Specific ◽  
Blood Flow Distribution ◽  
Reconstruction Process ◽  
Outflow Cannula ◽  
The Brain

AbstractThe primary objective of this research can be divided into two separate aspects. The first one was to verify whether own software can be treated as a viable source of data for the Computer Aided Design (CAD) modelling and Computational Fluid Dynamics CFD analysis. The second aspect was to analyze the influence of the Ventricle Assist Device (VAD) outflow cannula positioning on the blood flow distribution in the brain-supplying arteries. Patient-specific model was reconstructed basing on the DICOM image sets obtained with the angiographic Computed Tomography. The reconstruction process was performed in the custom-created software, whereas the outflow cannulas were added in the SolidWorks software. Volumetric meshes were generated in the Ansys Mesher module. The transient boundary conditions enabled simulating several full cardiac cycles. Performed investigations focused mainly on volume flow rate, shear stress and velocity distribution. It was proven that custom-created software enhances the processes of the anatomical objects reconstruction. Developed geometrical files are compatible with CAD and CFD software – they can be easily manipulated and modified. Concerning the numerical simulations, several cases with varied positioning of the VAD outflow cannula were analyzed. Obtained results revealed that the location of the VAD outflow cannula has a slight impact on the blood flow distribution among the brain supplying arteries.

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