Range of Critical Temperatures in Sick and Premature Newborn Babies

Abstract

The human baby, even if premature, shows evidence of homeothermy (Bruck, 1961; Day, Curtis, and Kelly, 1943). When subjected to a cool environment, his metabolic rate increases in an attempt to keep pace with increased heat loss. When subjected to an excessively warm environment, he becomes restless and active with hurried panting respiration so that again metabolic rate is increased. Between these two extremes is a small range of thermal environment known as the neutral range where metabolic rate is minimal. Since the thermal environment depends on ambient air temperature, air flow rate, relative humidity, and radiant heat exchange, it is inadequate to express such an environment in terms of a single temperature-the 'environmental temperature', unless other factors are controlled or eliminated. In this study, conductive heat loss was limited by lying the baby on a napkin, air flow rate was constant at about 1 m./ min., ambient vapour pressure (not relative humidity) was constant, and the walls of the baby chamber were opaque to radiant heat (for further details, see Scopes and Ahmed, 1966a).