A randomised double-blind controlled study evaluating the hypothermic effect of 150 μg morphine during spinal anaesthesia for Caesarean section

We studied the hypothermic effect of adding 150 mu g morphine during spinal anaesthesia in 60 parturients scheduled for elective caesarean section. All the parturients received intrathecal injection of a solution containing 150 mu g morphine or normal saline in addition to 10-12 mg hyperbaric bupivacaine 0.5%. In both groups, a significant decrease in body temperature was noted. There was no difference in the area under the curve for temperature against time for the two groups; however, the maximum decrease in temperature from baseline was significantly larger after morphine than after saline injection (mean (SD) 1.11 (0.61)degrees C vs 0.76 (0.39)degrees C, respectively; p=0.01) and the time to nadir temperature was significantly longer (593 (17.6) min vs 50.4 (15.9) min, respectively; p=0.047). The lowest temperature observed in the morphine group was 34.3 degrees C. We conclude that intrathecal injection of 150 mu g morphine intensified the intra-operative hypothermic effect of bupivacaine spinal anaesthesia for caesarean section.