Thermal energy balance as a measure of adequate rewarming from hypothermiccardiopulmonary bypass

Objective: To determine whether the amount of heat (thermal energy) used ac tively to rewarm patients on cardiopulmonary bypass (CPB) was a better indi cator of adequate rewarming from hypothermic CPB than core temperature. Design: Prospective study. Setting: Single hospital. Participants:Fifty-four sequential patients undergoing hypothermic CPB. Interventions: None. Measurements and Main Results: Thermal energy balance (TEB) (net heat suppl ied to or removed from the body, from initiation to termination of CPB) was measured using previously validated apparatus. Adequacy of rewarming was a ssessed by measuring the coldest postoperative core (tympanic membrane) tem perature and the time to rewarm postoperatively to a core temperature of 37 .0 degrees C. Core temperature on termination of CPB did not correlate with the degree of postoperative hypothermia as judged by time to rewarm postop eratively to 37.0 degrees C (r = 0.14; p = 0.33), but did correlate with co ldest postoperative core temperature (r = 0.47; p = 0.0003), TEB correlated better with time to rewarm to 37.0 degrees C (r = 0.43; p = 0.001) and col dest postoperative core temperature (r = 0.58, p = 0.0001). Conclusion: TEE is a better predictor than corresponding values of core tem perature on termination of CPB in predicting the coldest postoperative temp erature and time to rewarm to 37 degrees C. Copyright (C) 2000 by W.B. Saun ders Company.