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

We studied the hypothermic effect of adding 150 microg morphine during spinal anaesthesia in 60 parturients scheduled for elective caesarean section. All the parturients received intrathecal injection of a solution containing 150 mug 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 (59.5 (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 microg morphine intensified the intra-operative hypothermic effect of bupivacaine spinal anaesthesia for caesarean section.