Comparison of the effects of intrathecal morphine and pethidine on shivering after Caesarean delivery under combined‐spinal epidural anaesthesia*

We performed a prospective, randomised, double blind study to compare the antishivering effect of morphine and pethidine when added to intrathecal hyperbaric bupivacaine during elective Caesarean delivery under combined-spinal epidural anaesthesia. Spinal anaesthesia consisted of either 8-10 mg of 0.5% bupivacaine alone (group B; n = 30) with 0.1 mg morphine (group BM0.1; n = 29), with 0.2 mg morphine (group BM0.2; n = 30), or with 10 mg pethidine (group BPeth10; n = 30). The incidences of shivering were 23.3% (7/30) in group B, 17% (5/29) in group BM0.1, 13.3% (4/30) in group BM0.2 and 3.3% (1/30) in group BPeth10 (p < 0.05). The shivering intensity for each patient was significantly higher in group B than the other groups. In conclusion, intrathecal pethidine added to hyperbaric bupivacaine reduces the incidence and intensity of shivering more than does morphine (0.1 or 0.2 mg).