The Effects of Warming Intravenous Fluids, Sensory Block Level, and Skin Temperature on Postanesthetic Shivering during Spinal Anesthesia

Background: Shivering, which occurs in the postanesthetic period, annoys many patients, so we examined the correlation of postanesthetic shivering (PAS) and warming intravenous fluids, the level of sensory blockade, and skin temperature during spinal anesthesia. Methods : 65 patients undergoing an operation on a lower extremity were randomly allocated to 2 groups. The patients in group 1 and 2 received 500 ml of the unwarmed (ambient temperature) and warmed fluids prior to spinal anesthesia, respectively. All patients were anesthetized with 0.5% bupivacaine in 8% glucose. We measured the decrements of mean blood pressure (MBP) and heart rate, the highest sensory block level, and the increment of skin temperature 30 min after anesthesia, and the operating room temperature. After the operation we also evaluated the PAS by using the 10-mm visual anlalogue scale. Results : The decrement of MBP was higher in group 2 than in group 1 (13 mmHg vs 5 mmHg, P＜ 0.05). The highest sensory block level was higher in group 2 than in group 1 (T6.4 vs T7.6, P＜ 0.05). However, there was no significant difference in heart rate decrement, skin temperature increment, ambient temperature, and PAS between groups. The more the MBP decrement, the less the PAS in all patients (r = 0.326, P = 0.008) and in group 1 (r = 0.480, P = 0.005), but there was no correlation between PAS and MBP decrement in group 2. The more the ambient temperature, the less the PAS in all patients (r = 0.334, P = 0.007), in group 1 (r = 0.386, P = 0.027), and in group 2 (r = 0.394, P = 0.026). The heart rate decrement, skin temperature increment, and sensory blockade level did not correlate with PAS. Conclusions : PAS lowers as MBP decreases and operating room temperature increases during spinal anesthesia, but warming intravenous fluids, sensory block level, and skin temperature change doesn't affect PAS. (Korean J Anesthesiol 1999; 37: 787∼792)