Effect of extradural diamorphine on analgesia after caesarean section under subarachnoid block.

We have examined the efficacy, duration of action and side effects of extradural diamorphine alone and in combination with 1:200,000 adrenaline in a randomized, double-blind controlled study of 45 patients who underwent Caesarean section under spinal anaesthesia. Saline 10 ml, diamorphine 2.5 mg in saline 10 ml or diamorphine 2.5 mg in 1:200,000 adrenaline 10 ml were administered via the extradural route at delivery of the baby. Both diamorphine and diamorphine with adrenaline provided significantly prolonged analgesia compared with control (mean time to next analgesia (95% confidence interval) 17.3 h (12.0, 22.1 h), 15.9 h (10.6, 21.1 h), 5.7 h (1.5, 9.9 h), respectively) (P < 0.01). The addition of adrenaline increased the quality of analgesia 8 h after operation, but had no effect on the total amount of i.m. morphine administered during the first 24 h. The incidence of side effects was similar in all groups.