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 mu g.ml(-1), group 2 bupivacaine 0.125% with diamorphine 125 mu g.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 24h (p=0.351) or 48h (p=0.105). Motor block was significantly higher in group 2 (p<0.004) and pruritis 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.