Fig. 2. Core temperatures during and after cardiopulmonary bypass in patients assigned to forced-air heating or passive insulation during rewarming. The beginning of bypass cooling was designated time zero for cooling. Because the duration of cooling differed among patients, a second zero time was defined as the beginning of rewarming. Similarly, the end of rewarming identified time zero for the postbypass period. (Filled circles) Patients warmed with forced air. (Open circles) Control patients. Data are presented as the mean ± SD; see table 2for statistical analysis.