Effects of Low Dose Propofol on Core and Peripheral Temperatures during Spinal Anesthesia

Abstract

Background: Core hypothermia during the first hour after induction of anesthesia results primarily from a redistribution of body heat. Propofol in low doses provides reliable sedation and is associated with fast recovery. However, propofol-induced peripheral vasodilation is likely to facilitate core-to-peripheral heat redistribution. This study was designed to evaluate the effects of low dose propofol on core and peripheral temperatures during spinal anesthesia. Methods: Fifty patients of ASA status I or II, aged 20 to 60, undergoing lower extremity surgery under spinal anesthesia were studied. Spinal anesthesia was administered to all patients, who were assigned sedation as follows: 1) control (n = 25), 2) propofol (n = 25); propofol infusion rates were, 8 mg/kg/h for the first 3 min, 4 mg/kg/h for the next 10 min, and 2 mg/kg/h for the next 15 min. Temperatures were recorded after beginning surgery at 5-min intervals for 30 min. Results: Core temperature was significantly decreased after 15, 20, 30 min of surgery in the propofol group, and this result was statistically different between the two groups. Forearm skin temperature decreased in the control group and increased in the propofol group, without significance. Fingertip skin temperature did not changed significantly in the control group, but increased significantly after 15 min in the propofol group and continued to increasing to 30 min. Forearm minus finger skin temperature gradients were not changed significantly in control group, but decreased between 5 and 30 min in the propofol group, which was statistically significant. Conclusions: Low dose propofol may induce a degree of hypothermia during spinal anesthesia. Close monitoring is needed to prevent core hypothermia, if sedation is induced using propofol during spinal anesthesia.