Heat Tolerance in Patients with Extensive Healed Burns

Some thermoregulatory parameters of 10 subjects with healed burns were studied. The subjects, 4 of whom had healed burns of over 40 percent (group A) and 6 with burns smaller than 30 percent (group B) were assigned in a climatic chamber to 3 hours bench stepping (30 cm height) under 40 degrees C and 50 percent relative humidity. Rectal temperature, weighted skin temperature, heat storage, and heart rate were all found to be significantly higher in group A than in group B or group C (control group of normal subjects). No significant difference was observed between groups B and C. A highly significant linear correlation (r = 0.89) was found between the sweat rate and percentage of burned area. In addition, 3 subjects of group A terminated the study after less than 90 minutes. Two subjects in group B terminated the study after 120 and 135 minutes, while all subjects of group C finished the entire 3 hour work. The study indicates that subjects with burns of over 40 percent could be classified as heat intolerant due to a pronounced reduction in perspiration area.