Comparison of the effects of dexmedetomidine and propofol on hypothermia in patients under spinal anesthesia: a prospective, randomized, and controlled trial

Background: Redistribution hypothermia caused by vasodilation during anesthesia is the primary cause of perioperative hypothermia. Propofol exerts a dose-dependent vasodilatory effect, whereas dexmedetomidine induces peripheral vasoconstriction at high plasma concentrations. This study compared the effects of dexmedetomidine and propofol on core temperature in patients undergoing surgery under spinal anesthesia. Methods: This prospective study included 40 patients (aged 19-70 years) with American Society of Anesthesiologists Physical Status class I-III who underwent elective orthopedic lower-limb surgery under spinal anesthesia. Patients were randomly allocated to a dexmedetomidine or propofol group (n = 20 per group). After induction of spinal anesthesia, patients received dexmedetomidine (loading dose: 1 mu g/kg over 10 min; maintenance dose: 0.2-0.7 mu g/kg/h) or propofol (loading dose: 75 mu g/kg over 10 min; maintenance dose: 12.5-75 mu g/kg/min). The doses of sedatives were titrated to maintain moderate sedation. During the perioperative period, tympanic temperatures, thermal comfort score, and shivering grade were recorded. Results: Core temperature at the end of surgery did not differ significantly between the groups (36.4 +/- 0.4 and 36.1 +/- 0.7 degrees C in the dexmedetomidine and propofol groups, respectively; P = 0.118). The lowest perioperative temperature, incidence and severity of perioperative hypothermia, thermal comfort score, and shivering grade did not differ significantly between the groups (all P > 0.05). Conclusions: In patients undergoing spinal anesthesia with moderate sedation, the effect of dexmedetomidine on patients' core temperature was similar to that of propofol.