Fig. 10. Changes in core and peripheral tissue heat content during and after cardiopulmonary bypass at 31 and 27°C. The beginning of bypass cooling was designated as elapsed time zero for cooling. Because the duration of cooling differed among patients—and especially between the groups—a second zero elapsed time was defined as the beginning of rewarming. Similarly, the end of rewarming identified elapsed time zero for the postbypass period. Fewer data points are shown for the 31°C group (open circles) than for the 27°C group (filled circles) because both the cooling and the rewarming periods were shorter. In the 31°C group, total body heat content decreased 231 ± 93 kcal. During pump rewarming, peripheral heat content increased to 7 ± 27 kcal less than precooling values, whereas core heat content increased to 94 ± 33 kcal more than precooling values. Body heat content at the end of rewarming was 87 ± 42 kcal more than at the onset of cooling. In the 27°C group, total body heat content decreased 419 ± 49 kcal. During pump rewarming, core heat content increased to 66 ± 23 kcal more than precooling values, whereas peripheral heat content remained 70 ± 42 kcal less than precooling values. Body heat content at the end of rewarming was 4 ± 52 kcal less than at the onset of cooling. Results are presented as the mean ± SDs. Reprinted with permission from Rajek et al. 25