RESULTS	After three hours of anesthesia , the decrease in the tympanic membrane temperature from baseline ( preinduction ) was least in the forced-air warmer group ( -0.5 degrees C + / - 0.4 degrees C ) , intermediate in the circulating-water blanket group ( -1.2 degrees C + / - 0.4 degrees C ) , and greatest in the heated humidifier and control groups ( -2.0 degrees C + / - 0.5 degrees C and -2.0 degrees C + / - 0.7 degrees C , respectively ) .\