[Incidence of postoperative shivering in relation to the time of sevoflurane discontinuation].

OBJECTIVES: We aimed to determine whether early termination of sevoflurane administration lowers the incidence of postanesthetic shivering. MATERIAL AND METHODS: Eighty ASA I-III patients were randomized to two groups of 40 (Group A and Group B). All were premedicated with oral bromazepam. Fentanyl (2 micrograms/Kg), propofol (2.5 mg/Kg) and atracurium (0.5 mg/Kg) were used for induction. Anesthesia was maintained with sevoflurane in 60% N2O in oxygen at 1 maximum alveolar concentration, with boluses of fentanyl and atracurium on demand. Sevoflurane administration was terminated 30 minutes before awakening in group A and 10 minutes before awakening in group B. After termination, 60% N2O in oxygen was used in both groups. Mean blood pressure, heart rate and peripheral and core temperatures were measured at 5 minutes intervals during surgery. Postoperative shivering was recorded until one hour after awakening. RESULTS: Patient characteristics and duration of anesthesia were similar in both groups. The incidence of shivering was significantly lower in group A (4%) than in group B (57%). No significant differences were observed in other variables. CONCLUSIONS: The important observation in this study was that the incidence of postoperative shivering in group A was lower than in group B and lower than the incidences reported in other similar studies.