The mathematical modelling of thermal responses of normal subjects and burned patients

A model of the human thermoregulatory system has been developed for normal subjects and burned patients treated in the intensive care room at Aberdeen Royal Infirmary. The human body is split into eleven segments, each having core, muscle, fat and skin layers. Heat transport through blood flow and conduction are simulated, and surface heat loss is separated into radiative, convective and evaporative components. Measurement of skin temperature and evaporation of moisture have been made from all sections of the body for 22 normal subjects over a range of environmental temperatures from 20 degrees C to 40 degrees C. The model has been refined to fit the data through manipulation of heat flow commands and temperature set points controlling sweating and shivering. The model has been adapted to describe the responses of burn patients by the introduction of skin layer destruction, increased body metabolism and fluid loss from wounds. Predictions have been compared with measurements made on six patients. The model shows that the ambient temperature at which sweating occurs increases with the area of burn injury, which is confirmed by clinical observations. It has been used to predict optimum environmental temperatures for treatment of patients with burn wounds of varying extent.