MILD INTRAOPERATIVE HYPOTHERMIA PROLONGS POSTANESTHETIC RECOVERY

Background: Intraoperative hypothermia is common and persists for seve ral hours after surgery, Hypothermia may prolong immediate recovery by augmenting anesthetic potency, delaying drug metabolism, producing he modynamic instability, or depressing cognitive function, Accordingly, the authors tested the hypothesis that intraoperative hypothermia prol ongs postoperative recovery. Methods: Patients undergoing elective maj or abdominal surgery (n = 150) were anesthetized with isoflurane, nitr ous oxide, and fentanyl. They were randomly assigned to routine therma l management (hypothermia) or extra it warming (normothermia). Postope rative surgical pain was treated with patient-controlled analgesia. Fi tness for discharge from the postanesthesia care unit was evaluated at 20-min intervals by investigators blinded to group assignment and pos toperative core temperatures, Scoring was based on a modification of a previously published system that included activity, ventilation, cons ciousness, and hemodynamic responses, Patients were considered fit for discharge when they sustained a score of 80% (13 points) for at least two consecutive measurement periods. Results: Morphometric characteri stics and anesthetic management mere similar in each group, Final intr aoperative core temperatures differed by approximate to 2 degrees C: 3 4.8 +/- 0.6 versus 36.7 +/- 0.6 degrees C (mean +/- SD, P < 0.001). Po stoperative pain scores and postoperative use of patient-controlled op ioid were similar, Hypothermic patients required approximate to 40 min longer (94 +/- 65 tis, 53 +/- 36 min) to reach fitness for discharge, even when return to normothermia was not a criterion (p < 0.001). Dur ation of recovery in the two groups differed by approximate to 90 min when a core temperature >36 degrees C was also required (p < 0.001). C onclusion: Maintaining core normothermia decreases the duration of pos tanesthetic recovery and may, therefore, reduce costs of care.