Premature infants are less capable of maintaining thermal balance of head and body with increases of thermal environment than with decreases.

We investigated whether premature infants nursed at the upper range of normal body temperature are more capable of maintaining their nasopharyngeal and rectal temperature when exposed to a 1 degrees C increase or a 1 degrees C decrease of incubator temperature. In a randomized controlled trial, premature infants were exposed to a 1 degrees C increase (T + 1 degrees C; n = 10), or to a 1 degrees C decrease (T - 1 degrees C; n = 10) of incubator temperature. Nasopharyngeal, rectal, and skin temperatures as well as heat flux at various sites, heart rate, and activity were measured over a 6-hour period. The absolute changes in core temperatures, Tnasoph and Trectal, were significantly greater in the T + 1 degrees C compared with T - 1 degrees C (T + 1 degrees C versus T - 1 degrees C: Tnasoph 0.44 +/- 0.31 degrees C and 0.18 +/- 0.14 degrees C respectively; p < 0.001; T(rectal) 0.43 +/- 0.30 degrees C and 0.25 +/- 0.10 degrees C, respectively; p < 0.01) when exposed to the increase or decrease in incubator temperature. Premature infants are less able to cope with increases in incubator temperature given that rectal and nasopharyngeal temperature change more when environmental temperature is increased.