Quantification of redistribution hypothermia

Overall heat balance was calculated from the difference between metabolic heat production and heat loss. To separate the contributions of decreased overall heat balance and internal redistribution of body heat to the decrease in core temperature, the change in overall heat balance was multiplied by body weight and the specific heat of humans. The resulting change in mean body temperature ("mean body") was subtracted from the change in core temperature ("core"), leaving the core hypothermia specifically resulting from redistribution ("redistribution"). After one hour of anesthesia, core temperature had decreased 1.6±0.3°C, with redistribution contributing 81% to the decrease. During the subsequent two hours of anesthesia, core temperature decreased an additional 1.1±0.3°C, with redistribution contributing only 43%. Redistribution thus contributed 65% to the entire 2.8±0.5°C decrease in core temperature during the three hours of anesthesia. Induction of general anesthesia is identified as elapsed time zero.