CONSEQUENCES OF A SMALL DECREASE OF AIR-TEMPERATURE FROM THERMAL-EQUILIBRIUM ON THERMOREGULATION IN SLEEPING NEONATES

A new heating unit (servocontrolled skin temperature derivative system ) has been designed to control the thermal environment in closed incub ators. This type of control acts to attain and closely maintain a ther mal equilibrium between a neonate's skin temperature and the environme nt. The present study aims to discover if thermal equilibrium is locat ed within a thermoneutral range defined from oxygen consumption ((V)ov er dot O-2) and body temperature, and whether it is more appropriate t o define an optimal thermal environment. As regards (V)over dot O-2 an d body temperature, results show that the air temperature reached at t hermal equilibrium fulfils the definition of thermoneutrality. Accordi ng to these criteria, a small decrease (1.5 degrees C) from thermal eq uilibrium also provides a near thermoneutral environment to the neonat e but induces sleep disturbances and an increase in body movements. Th ese two additional parameters delineate a narrower thermoneutral zone than does minimal metabolic rate because (V)over dot O-2 can stay cons tant even when air and body temperatures decrease. The results suggest that thermal equilibrium might be assimilated with a thermal comfort zone.