Determinants of core temperature at the time of admission to intensive care following cardiac surgery

Objective: To determine the predictors of core temperature on arrival in th e intensive care unit (ICU) after cardiac surgery. Design: Prospective, ran domized trial. Setting: Tertiary care medical center, operating rooms (ORs), and ICU. Patients: 72 patients presenting for coronary artery bypass surgery. Intervention: Randomized assignment for ambient OR temperature (16-18 degre es C vs. 21-23 degrees C) and rewarming endpoint on cardiopulmonary bypass (CPB; nasopharyngeal and urinary bladder temperatures greater than or equal to 36.5 degrees and 34.0 degrees C, respectively vs. nasopharyngeal and ur inary bladder temperatures greater than or equal to 37.5 degrees and 36.0 d egrees C, respectively) at the time of separation from bypass. Measurements and Main Results: The best (and only significant) predictor of core temperature on arrival in the ICU was rewarming endpoint at the time of separation from CPB (p = 0.004). Patient weight, height, body habitus, a nd nitroprusside administration did not significantly predict core temperat ure. Ambient temperature affected only body temperature when the duration o f time in the OR after separation from bypass was prolonged (>90 min). A we ighted average body temperature was a better predictor of complete rewarmin g than was any single monitoring site. Conclusions: To reduce the incidence of hypothermia after cardiac surgery, the most important variable is rewarming endpoint achieved before separatio n from bypass. A warm ambient temperature (>21 degrees C) may be beneficial if the duration of time in the OR after bypass is prolonged (>90 min). (C) 2000 Elsevier Science Inc.