Theory and Experiment for the Effect of Vascular Microstructure on Surface Tissue Heat Transfer—Part II: Model Formulation and Solution

1984 ◽  
Vol 106 (4) ◽  
pp. 331-341 ◽  
Author(s):  
L. M. Jiji ◽  
S. Weinbaum ◽  
D. E. Lemons
Keyword(s):  
Heat Transfer ◽  
Analytic Solution ◽  
Blood Perfusion ◽  
Skin Surface ◽  
Quantitative Model ◽  
Number Density ◽  
Model Formulation ◽  
Physiological Conditions ◽  
Vascular Geometry ◽  
Theory And Experiment

In this paper the conceptual three-layer representation of surface tissue heat transfer proposed in Weinbaum, Jiji and Lemons [I], is developed into a detailed quantitative model. This model takes into consideration the variation of the number density, size and flow velocity of the countercurrent arterio-venous vessels as a function of depth from the skin surface, the directionality of blood perfusion in the transverse vessel layer and the superficial shunting of blood to the cutaneous layer. A closed form analytic solution for the boundary value problem coupling the three layers is obtained. This solution is in terms of numerically evaluated integrals describing the detailed vascular geometry, a capillary bleed-off distribution function and parameters describing the shunting of blood to the cutaneous layer. Representative heat transfer results for typical physiological conditions are presented.

Numerical Simulation of Enhanced Skin Thermal Signature of Female Breast Tumor Subjected to Forced Convection

2003 ◽  
Author(s):  
A. Gupta ◽  
L. Hu ◽  
J. P. Gore ◽  
L. X. Xu
Keyword(s):  
Heat Transfer ◽  
Flow Field ◽  
Skin Temperature ◽  
Forced Convection ◽  
Infrared Imaging ◽  
Transfer Problem ◽  
Blood Perfusion ◽  
Skin Surface ◽  
Temperature Distributions ◽  
Thermal Signature

Early detection is considered to be the best defense against breast cancer and imaging plays a very important role in screening and in the diagnosis of symptomatic women. Infrared thermal imaging of skin temperature changes caused by a malignant tumor in breast is a rapidly developing detection modality with potential for functional detection. Knowledge and control of environmental factors which affect the skin temperature can reduce misinterpretations and false diagnosis associated with infrared imaging. A bio heat transfer based numerical model was utilized to study the energy balance in healthy and malignant breasts subjected to low velocity forced convection in a wind tunnel. Existing estimates of metabolic heating rates and previous measurements of temperature distributions along the radial direction in a region intersecting a known tumor and a comparable region in the healthy breast of the same patient were used to estimate the blood perfusion rates for the tumor. A simplified structural and thermal model was used for representing the changes within and around the tumor. Steady state temperature distributions on the skin surface of the breasts were obtained by numerically solving the conjugate heat transfer problem. Parametric studies on the influences of the airflow on the skin thermal expression of tumors were performed. It was found that the presence of tumor may not be clearly shown due to the irregularity of the skin temperature distribution induced by the flow field. Image processing techniques could be employed to eliminate the effects of the flow field and thermal noise and significantly improve the thermal signature of the tumor on the skin surface.

A Theoretical Model for Peripheral Tissue Heat Transfer Using the Bioheat Equation of Weinbaum and Jiji

1987 ◽  
Vol 109 (1) ◽  
pp. 72-78 ◽  
Author(s):  
Wei Jie Song ◽  
Sheldon Weinbaum ◽  
Latif M. Jiji
Keyword(s):  
Heat Transfer ◽  
Numerical Solutions ◽  
Quantitative Model ◽  
Peripheral Tissue ◽  
Whole Body ◽  
Bioheat Equation ◽  
One Dimensional ◽  
Physiological Conditions ◽  
Tissue Organization ◽  
Body Heat

In this paper the new bioheat equation derived in Weinbaum and Jiji [7] is applied to the three layer conceptual model of microvascular surface tissue organization proposed in [1]. A simplified one-dimensional quantitative model of peripheral tissue energy exchange is then developed for application in limb and whole body heat transfer studies. A representative vasculature is constructed for each layer and the enhancement in the local tensor conductivity of the tissue as a function of vascular geometry and blood flow is examined. Numerical solutions for the boundary value problem coupling the three layers are presented and these results used to study the thermal behavior of peripheral tissue for a wide variety of physiological conditions from supine resting state to maximum exercise.

scholarly journals The Use of Core Warming as a Treatment for Coronavirus Disease 2019 (COVID-19): an Initial Mathematical Model

2020 ◽  
Vol 33 (1) ◽  
pp. 6-15 ◽  
Author(s):  
Marcela Mercado-Montoya ◽  
Nathaniel Bonfanti ◽  
Emily Gundert ◽  
Anne Meredith Drewry ◽  
Roger Bedimo ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Viral Entry ◽  
Therapeutic Option ◽  
Blood Perfusion ◽  
Skin Surface ◽  
The Body ◽  
Hospital Environment ◽  
Body Region ◽  
Temperature Sensitive ◽  
Available Technology

Background: Increasing data suggest that elevated body temperature may be helpful in resolving a variety of diseases, including sepsis, acute respiratory distress syndrome (ARDS), and viral illnesses. SARS-CoV-2, which causes coronavirus disease 2019 (COVID-19), may be more temperature sensitive than other coronaviruses, particularly with respect to the binding affinity of its viral entry via the ACE2 receptor. A mechanical provision of elevated temperature focused in a body region of high viral activity in patients undergoing mechanical ventilation may offer a therapeutic option that avoids arrhythmias seen with some pharmaceutical treatments. We investigated the potential to actively provide core warming to the lungs of patients with a commercially available heat transfer device via mathematical modeling, and examine the influence of blood perfusion on temperature using this approach. Methods: Using the software Comsol Multiphysics, we modeled and simulated heat transfer in the body from an intraesophageal warming device, taking into account the airflow from patient ventilation. The simulation was focused on heat transfer and warming of the lungs and performed on a simplified geometry of an adult human body and airway from the pharynx to the lungs. Results: The simulations were run over a range of values for blood perfusion rate, which was a parameter expected to have high influence in overall heat transfer, since the heat capacity and density remain almost constant. The simulation results show a temperature distribution which agrees with the expected clinical experience, with the skin surface at a lower temperature than the rest of the body due to convective cooling in a typical hospital environment. The highest temperature in this case is the device warming water temperature, and that heat diffuses by conduction to the nearby tissues, including the air flowing in the airways. At the range of blood perfusion investigated, maximum lung temperature ranged from 37.6°C to 38.6°C. Conclusions: The provision of core warming via commercially available technology currently utilized in the intensive care unit, emergency department, and operating room can increase regional temperature of lung tissue and airway passages. This warming may offer an innovative approach to treating infectious diseases from viral illnesses such as COVID-19, while avoiding the arrhythmogenic complications of currently used pharmaceutical treatments.

Flow-mediated release of nitric oxide in isolated, perfused rabbit lungs

2001 ◽  
Vol 91 (1) ◽  
pp. 363-370 ◽  
Author(s):  
Toshiyuki Ogasa ◽  
Hitoshi Nakano ◽  
Hiroshi Ide ◽  
Yasushi Yamamoto ◽  
Nobuhiko Sasaki ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Baseline Level ◽  
Pulmonary Arterial Pressure ◽  
Blood Perfusion ◽  
No Production ◽  
Perfusion Study ◽  
Capillary Recruitment ◽  
Physiological Conditions ◽  
Perfusate Flow ◽  
Pulmonary Arterial

The effects of changing perfusate flow on lung nitric oxide (NO) production and pulmonary arterial pressure (Ppa) were tested during normoxia and hypoxia and after N G-monomethyl-l-arginine (l-NMMA) treatment during normoxia in both blood- and buffer-perfused rabbit lungs. Exhaled NO (eNO) was unaltered by changing perfusate flow in blood-perfused lungs. In buffer-perfused lungs, bolus injections of ACh into the pulmonary artery evoked a transient increase in eNO from 67 ± 3 (SE) to 83 ± 7 parts/billion with decrease in Ppa, whereas perfusate NO metabolites (pNOx) remained unchanged. Stepwise increments in flow from 25 to 150 ml/min caused corresponding stepwise elevations in eNO production (46 ± 2 to 73 ± 3 nl/min) without changes in pNOx during normoxia. Despite a reduction in the baseline level of eNO, flow-dependent increases in eNO were still observed during hypoxia.l-NMMA caused declines in both eNO and pNOx with a rise in Ppa. Pulmonary vascular conductance progressively increased with increasing flow during normoxia and hypoxia. However,l-NMMA blocked the flow-dependent increase in conductance over the range of 50–150 ml/min of flow. In the more physiological conditions of blood perfusion, eNO does not reflect endothelial NO production. However, from the buffer perfusion study, we suggest that endothelial NO production secondary to increasing flow, may contribute to capillary recruitment and/or shear stress-induced vasodilation.

scholarly journals Solving bio-heat transfer multi-layer equation using Green’s Functions method

2021 ◽  
Vol 2090 (1) ◽  
pp. 012150
Author(s):  
de Oliveira Eduardo Peixoto ◽  
Gilmar Guimaräes
Keyword(s):  
Heat Transfer ◽  
Green's Functions ◽  
Green’S Functions ◽  
Transfer Problem ◽  
Blood Perfusion ◽  
The Body ◽  
Mathematical Background ◽  
Number Of Layers ◽  
Pennes Equation ◽  
Transfer Problems

Abstract An analytical method using Green’s Functions for obtaining solutions in bio-heat transfer problems, modeled by Pennes’ Equation, is presented. Mathematical background on how treating Pennes’ equation and its μ2T term is shown, and two contributions to the classical numbering system in heat conduction are proposed: inclusion of terms to specify the presence of the fin term, μ2T, and identify the biological heat transfer problem. The presentation of the solution is made for a general multi-layer domain, deriving and showing general approaches and Green’s Functions for such n number of layers. Numerical examples are presented to simplify human skin as a two-layer domain: dermis and epidermis, accounting metabolism as a heat source, and blood perfusion only at the dermis. Time-independent summations in the series-solution are written in closed forms, leading to better convergence along the boundaries. Details on obtaining the two-layer solution and its eigenvalues are presented for boundary conditions of prescribed temperature inside the body and convection at the surface, such as its intrinsic verification.

Formulation of a Statistical Model of Heat Transfer in Perfused Tissue

1994 ◽  
Vol 116 (4) ◽  
pp. 521-527 ◽  
Author(s):  
J. W. Baish
Keyword(s):  
Heat Transfer ◽  
Heat Transport ◽  
Drug Transport ◽  
Transfer Problem ◽  
Three Dimensional ◽  
Tissue Temperature ◽  
Statistical Interpretation ◽  
Transfer Equations ◽  
Vascular Geometry ◽  
Steady State Heat

A new model of steady-state heat transport in perfused tissue is presented. The key elements of the model are as follows: (1) a physiologically-based algorithm for simulating the geometry of a realistic vascular tree containing all thermally significant vessels in a tissue; (2) a means of solving the conjugate heat transfer problem of convection by the blood coupled to three-dimensional conduction in the extravascular tissue, and (3) a statistical interpretation of the calculated temperature field. This formulation is radically different from the widely used Pennes and Weinbaum-Jiji bio-heat transfer equations that predict a loosely defined local average tissue temperature from a local perfusion rate and a minimal representation of the vascular geometry. Instead, a probability density function for the tissue temperature is predicted, which carries information on the most probable temperature at a point and uncertainty in that temperature due to the proximity of thermally significant blood vessels. A sample implementation illustrates the dependence of the temperature distribution on the flow rate of the blood and the vascular geometry. The results show that the Pennes formulation of the bio-heat transfer equation accurately predicts the mean tissue temperature except when the arteries and veins are in closely spaced pairs. The model is useful for fundamental studies of tissue heat transport, and should extend readily to other forms of tissue transport including oxygen, nutrient, and drug transport.

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