Background and Objectives Low-dose subarachnoid morphine provides effective perioperative analgesia but may be associated with a transient period of inadequate pain relief between the regression of local anesthetic block and the onset of morphine's analgesic effect. We hypothesized that this period of suboptimal analgesia could be avoided by adding meperidine, a rapid-acting, intermediate-duration opioid.

Methods In a double-blind, randomized trial, 49 patients scheduled for elective cesarean delivery received subarachnoid 0.75% bupivacaine, 12 mg in 8.25% dextrose, with either meperidine 10 mg, morphine 0.15 mg, or meperidine 10 mg plus morphine 0.15 mg. Visual analog scale scores for pain and satisfaction were obtained at skin incision, delivery, uterine exteriorization, on arrival in the postanesthesia care unit, and 2, 4, 6, 12, and 24 hours after drug administration. Neonatal Apgar scores and adverse effects were also noted. Postoperative intravenous patient-controlled analgesia (PCA) requirements were recorded for 24 hours. The data were analyzed by chi-square analysis Fisher's exact test, the Wilcoxon rank sum test, and analysis of variance with Tukey's adjustment for multiple comparisons.

Results There were no significant differences in the incidence and severity of side effects, including nausea, vomiting, pruritus, and sedation. Respiratory depression was not observed. Patients treated with morphine alone were least comfortable (P < .006), expressed the lowest satisfaction scores at early observations (P < .002), and required more PCA meperidine (P < .001) than any other group. Patients treated with meperidine alone were comfortable at early observations but required the greatest total amount of PCA meperidine over the first 24 hours (P < .05). Patients in the meperidine-morphine combination group reported the lowest pain scores and highest satisfaction scores at 4-hour and 6-hour observations (P < .03) and required the least total amount of PCA meperidine.

Conclusion The subarachnoid combination of meperidine-morphine provided more uniform analgesia, higher satisfaction, and a lower requirement for intravenous narcotic supplementation than either morphine or meperidine alone in patients recovering from cesarean delivery.