Effect of ambient temperature on heat production and heat loss in burn patients.

Four controls and eight burned patients with thermal injury ranging from 7 to 84% total body surface were studied in an environmental chamber at 25 and 33 degrees C ambient temperature and a constant vapor pressure during two consecutive 24-h periods. Hypermetabolism was present in the burn patients in both ambient temperatures and core and skin temperatures were consistently higher than in the normal men despite increased evaporative water loss. The higher environmental temperature decreased metabolic rate in patients with large thermal injuries in whom the decrement in dry heat loss produced by higher ambient temperature exceeded the increase of wet heat loss. In patients with burns smaller than 60%, these changes equaled one another and higher environmental temperature exerted no effect on metabolic rate. Core-skin heat conductivity increased with burn size; patients with large burns were characterized by inadequate core-skin insulation when exposed to the cooler environment, necessitating the compensatory increase of metabolic rate. This increase, however, was small and of the order of 5-8 kcal times m-2 times h-1.