A comparison of opioid solutions for patient-controlled epidural analgesia

Sixty patients took part in a randomised, double-blind study to compare the analgesic and side effects of three opioid-containing solutions for patient-controlled epidural analgesia following abdominal surgery. Patients in group 1 received a solution containing bupivacaine 0.125% with fentanyl 10 micrograms.ml-1, group 2 bupivacaine 0.125% with diamorphine 125 micrograms.ml-1, group 3 pethidine 2.5 mg.ml-1. All groups received 4 ml.h-1 background infusion and 3 ml boluses every 20 min if necessary. There were no significant differences between the groups in visual analogue scale pain scores (p = 0.537) or volumes of solution used at 24 h (p = 0.351) or 48 h (p = 0.105). Motor block was significantly higher in group 2 (p < 0.004) and pruritus occurred significantly less in group 3 (p < 0.05). We conclude that these three solutions produce equivalent analgesia but that pethidine 2.5 mg.ml-1 may be associated with fewer side effects.