Quantitation of thermoregulatory impairment in patients with healed burns

The basis of our study lies in the clear demonstration that rectal temperature in cool and comfortable environments is a function of the metabolic load but that once a critical level of environmental warmth has been exceeded, the rectal temperature increases above the metabolically controlled level. This effect forms the basis of the presently suggested limits for healthy individuals during heat exposure in industry. We show that impairment of thermoregulation due to extensive burns makes such environmental limits unacceptable. Our experiment was aimed at demonstrating certain tolerance limits above which the extensively burned patient (40% deep second- or third-degree burns) cannot realistically be expected to function under the workload employed. Nine subjects with varying degrees of anhidrosis were subjected to standard workloads under carefully controlled environmental conditions. We found a dramatic diminution in heat tolerance in patients with healed burns covering more than 40% of their body surface area.