A CALORIMETRIC SYSTEM FOR METABOLIC STUDIES OF NEWBORN BABIES

A closed circuit calorimetric system designed to determine the amount of energy required for synthesis of new tissue in a newborn baby is described. This amount can be estimated from the difference between indirect and direct calorimetric measurements. The system allows the simultaneous measurement of O2 consumption, CO2 production, evaporative water loss and heat loss through convection and radiation in newborn babies under 2.5 kg body wt. The babies are exposed to a well defined climate, they can be observed continuosly and are fed via a nasogastric tube during the experiment, which may last 24 h or more. Special features of the system are the compensation methods for O2 and CO2 measurements and the double gradient layer for the measurement of dry heat loss. The overall accuracy of the system is of the order of 0.1 W. The value obtained for the energy cost of growth is in close agreement with Hommes'' theoretical estimate.