Regional skin temperature, heat flow and conductance in preterm neonates nursed in low and in neutral environmental temperature.

The changes of regional dry heat loss and skin temperature in 15 healthy preterm babies, 8 with a gestational age (GA) of 33-36 weeks and 7 with a GA of 28-31 weeks, were studied under controlled conditions at environmental temperatures ranging from 29.5 to 34.0 degrees C. In both groups of babies the skin temperature for all body regions followed the changes in operative temperatures. Regional dry heat losses also closely followed the external temperature gradient. In the 33-36 weeks GA neonates the regional changes in thermal conductance (index of cutaneous blood flow) indicated that only the foot responded to low environmental temperature with vasoconstriction while vasodilatation was indicated for the trunk. In the 28-31 weeks GA neonates similar but not significant changes of thermal conductance were calculated. The limited ability to reduce heat loss by reducing the skin conductance over a major part of the body surface area contributes to the vulnerability to low environmental temperature in preterm neonates.