Theoretical analysis of evaporative cooling of classic heat stroke patients

Abstract

Heat stroke is a serious health concern globally, which is associated with high mortality. Newer treatments must be designed to improve outcomes. The aim of this study is to evaluate the effect of variations in ambient temperature and wind speed on the rate of cooling in a simulated heat stroke subject using the dynamic model of Wissler. We assume that a 60-year-old 70-kg female suffers classic heat stroke after walking fully exposed to the sun for 4h while the ambient temperature is 40°C, relative humidity is 20%, and wind speed is 2.5m/s-1. Her esophageal and skin temperatures are 41.9 and 40.7°C at the time of collapse. Cooling is accomplished by misting with lukewarm water while exposed to forced airflow at a temperature of 20 to 40°C and a velocity of 0.5 or 1m/s-1. Skin blood flow is assumed to be either normal, one-half of normal, or twice normal. At wind speed of 0.5m/s-1 and normal skin blood flow, the air temperature decreased from 40 to 20°C, increased cooling, and reduced time required to reach to a desired temperature of 38°C. This relationship was also maintained in reduced blood flow states. Increasing wind speed to 1m/s-1 increased cooling and reduced the time to reach optimal temperature both in normal and reduced skin blood flow states. In conclusion, evaporative cooling methods provide an effective method for cooling classic heat stroke patients. The maximum heat dissipation from the simulated model of Wissler was recorded when the entire body was misted with lukewarm water and applied forced air at 1m/s at temperature of 20°C.