Effect of radiant heat on head temperature gradient in term infants.

AIMS To test the hypothesis that external radiant heating might lead to significant fluctuations in superficial and core head temperatures in newborn infants. METHODS In an observation group of 14 term infants nursed under a radiant heater, servo-controlled to the abdominal skin, changes in rectal, core head, and scalp temperatures with heater activation were examined. In a further intervention group of six infants the effect of a reflective head shield on the fluctuations of scalp temperature was also tested. RESULTS In the observation group, when the heater had been off for 30 minutes, the rectal and scalp temperatures were 36.7 (SD 0.6) and 35.6 (0.6) degrees C, respectively, a difference of 1.2 (0.2) degrees C. After 30 minutes with the radiant heater on this fell to 0.2 (0.5) degrees C. The core head temperature, however, remained similar to the rectal temperature throughout. In the intervention group a reflective shield prevented the loss of the rectal-scalp gradient. CONCLUSION Overhead heater activation is associated with loss of the core to scalp temperature gradient, but no change in core head temperature in term infants. The clinical relevance of this superficial heating in vulnerable infants warrants further study.