Figure 40-9 Changes in body heat content and distribution of heat within the body during induction of general anesthesia (at elapsed time zero). Subtraction of the change in mean body temperature from the change in core (tympanic membrane) temperature results in the core hypothermia specifically attributable to redistribution. Redistribution hypothermia was thus not a measured value; instead, it is defined by the decrease in core temperature not explained by the relatively small decrease in systemic heat content. After 1 hour of anesthesia, core temperature had decreased 1.6°C ± 0.3°C, with redistribution contributing 81% to the decrease. Even after 3 hours of anesthesia, redistribution contributed 65% to the entire 2.8°C ± 0.5°C decrease in core temperature. Results are presented as means ± SD. (Redrawn with modification from Matsukawa T, Sessler DI, Sessler AM, et al: Heat flow and distribution during induction of general anesthesia. Anesthesiology 82:662–673, 1995.)