50 Years of Computer Simulation of the Human Thermoregulatory System

Abstract

This paper presents an updated and augmented version of the Wissler human thermoregulation model that has been developed continuously over the past 50 years. The existing Fortran code is translated into C with extensive embedded commentary. A graphical user interface (GUI) has been developed in Python to facilitate convenient user designation of input and output variables and formatting of data presentation. Use of the code with the GUI is described and demonstrated. New physiological elements were added to the model to represent the hands and feet, including the unique vascular structures adapted for heat transfer associated with glabrous skin. The heat transfer function and efficacy of glabrous skin is unique within the entire body based on the capacity for a very high rate of blood perfusion and the novel capability for dynamic regulation of blood flow. The model was applied to quantify the absolute and relative contributions of glabrous skin flow to thermoregulation for varying levels of blood perfusion. The model also was used to demonstrate how the unique features of glabrous skin blood flow may be recruited to implement thermal therapeutic procedures. We have developed proprietary methods to manipulate the control of glabrous skin blood flow in conjunction with therapeutic devices and simulated the effect of these methods with the model.

Heat Transfer in Health and Healing1

“…Vasodilation occurs progressively above 38 C core temperature. Normothermic perfusion exists for the plateau of states between these thresholds [57]. Hysteresis occurs in transitions to normothermia.…”

“…Figure 5 is a simplified cartoon of the nodal connectedness of the model. The elements for the hands and feet are components added recently to represent the glabrous skin areas and mass of the hands and feet [57].…”

Effect of sympathetic nerve blockade on low‐frequency oscillations of forearm and leg skin blood flow in healthy humans

“…While the majority of research has been conducted on the skin of the forearm, we and others have reported marked regional differences in the mechanisms of control of the vasodilation response to local heating . Thus, if we are to properly understand and appropriately model the role of skin blood flow in thermoregulation, an understanding of both the mechanisms of control and associated regional variations is required.…”

On the Evolution of Thermoregulation Models

“…As stressed by Hensley et al [1] and Havenith and Fiala [2], in recent years there has been a growing demand from industry for robust and reliable models predicting human thermophysiological responses. In several applications is required a detailed analysis of the complex environmental heat transfer processes involving human occupancy in order to design safe, comfortable and energy-efficient buildings, in biomedical applications, in cars, or industrial environments in the presence of heat related injuries and also in military and sport [3][4][5][6][7][8][9][10].…”