Morphine and hydromorphone epidural analgesia. A prospective, randomized comparison.

Because evidence from uncontrolled, unblinded studies suggested fewer side effects from epidural hydromorphone than from epidural morphine, we employed a randomized, blinded study design to compare the side effects of lumbar epidural morphine and hydromorphone in 55 adult, non-obstetric patients undergoing major surgical procedures. A bolus dose of epidural study drug was given at least 1 h prior to the conclusion of surgery, followed by a continuous infusion of the same drug for two postoperative days. Infusions were titrated to patient comfort. Visual analog scale (VAS) pain scores, VAS sedation scores, and subjective ratings of nausea and pruritus were assessed twice daily. The two treatments provided equivalent analgesia. Sedation scores and prevalence of nausea did not differ significantly between groups. Prevalence of pruritus, however, differed significantly on postoperative day 1, with moderate to severe pruritus reported by 44.4% of patients in the morphine group versus 11.5% in the hydromorphone group (P < .01). On post-operative day 2, reports of pruritus by patients receiving morphine remained higher than those among the hydromorphone-treated subjects, although this difference was no longer statistically significant (32% vs. 16.7%, P = .18). We conclude that lumbar epidural morphine and hydromorphone afford comparable analgesia, but the occurrence of moderate to severe pruritus on the first postoperative day is reduced by the use of hydromorphone.