The influence of ambient temperature on some commonly measured physiological variables in infants.

Fifty-four infants underwent recording of heart rate, respiratory rate, long term and short term heart rate variability and end tidal carbon dioxide measurements at three different ambient temperatures (20 degrees C, 25-26 degrees C, 30 degrees C) under standardized conditions. The infants' skin and rectal temperature remained normal throughout the study. The ambient temperature of the room where the study was conducted significantly influenced the infants' heart rate, respiratory rate and long and short term heart rate variability but not end tidal carbon dioxide values. The thermal environment in which an infant resides has a significant influence on some physiological variables and should be standardized in future physiological studies.