Diamorphine analgesia after caesarean section. Comparison of intramuscular and epidural administration of four dose regimens.

In a randomised double-blind study, the efficacy, duration of action and side effects of five diamorphine analgesia regimens following Caesarean section are described. The time to next analgesia was shorter in the 5 mg intramuscular group (3.53 hours) than in any of the four epidural groups: 5 mg (5.7 hours, p = 0.007), 2.5 mg (4.76 hours, p = 0.103), 5 mg with adrenaline 1/200,000 (7.2 hours, p = 0.001) and 2.5 mg with adrenaline 1/200,000 (6.05 hours, p = 0.007). Multiple regression analysis showed that the addition of adrenaline significantly increased the duration of action of epidural diamorphine (p less than 0.05). The 5 mg dose with adrenaline showed no advantage when compared with 2.5 mg with adrenaline (p = 0.16). No serious side effects were reported in any group.