Intrathecal diamorphine compared with morphine for postoperative analgesia after Caesarean section under spinal anaesthesia

A randomized, double-blind study of 40 women was performed to compare patient controlled anaesthesia (PCA) morphine requirements after spinal anaesthesia for elective Caesarean section. The women received 0.2 mg of either morphine or diamorphine mixed with 0.5% bupivacaine in 8% dextrose. There were no significant differences between the groups in terms of VAS for pain, either while supine or trying to turn over. The median VAS for itching were significantly higher in the morphine group at 3, 4, 6, 8 and 12 h. Similarly, the VAS for drowsiness were significantly higher in the morphine group at 6 and 8 h. Overall there was no difference in the 24-h PCA morphine demands between the two groups (diamorphine patients 5.5 mg, morphine patients 5.0 mg.