A calorimeter for simultaneous determination of heat production and heat loss in the rat.

Abstract

A gradient calorimeter was constructed for rodents which allows simultaneous measurements of heat production by indirect calorimetry and partitioned heat loss by direct means. The over-all response time of the calorimeter is less than 5 min. Details of calorimeter construction are given. Simultaneous direct and indirect calorimetric measurements were made on burned and unburned albino rats on the 8th, 15th, 22nd, 29th, 36th, and 43rd postburn days. Wound eschars were removed on the 21st postburn day. The data demonstrate a significant increment in vaporizational heat loss for the burned animals which maximizes to a fivefold increase with eschar separation. At ambient wall temperatures of 28[degree]C. there is an increment in heat production corresponding to the increment in vaporizational heat loss. Increasing the ambient air and wall temperatures results in a decrement in dry heat loss, a corresponding decrement in total heat production, and no change In vaporizational heat loss of the burned animals. The host is the obligate source of energy for the vaporizational heat loss from the burn wound.