A RANDOMIZED, DOUBLE-BLIND, DOSE-RESPONSE COMPARISON OF EPIDURAL FENTANYL VERSUS SUFENTANIL ANALGESIA AFTER CESAREAN-SECTION

This study was designed to determine and compare the dose-response cha racteristics, speed of onset, and relative potency of single-dose epid ural fentanyl (F) and sufentanil (S) for postoperative pain relief. Ei ghty women undergoing cesarean section (C/S) with epidural 2% lidocain e with epinephrine (1:200,000) were randomly assigned to receive doubl e-blind epidural administration of F (25, 50, 100, or 200 mu g) or S ( 5, 10, 20, or 30 mu g) (n = 10 per group) upon complaint of pain posto peratively. Visual analog scales (VAS, 0-100 mm) were used to assess p ain and sedation at baseline; at 3, 6, 9, 12, 15, 20, 25, 30, 45, and 60 min; and every 30 min until further analgesia was requested. The st udy was terminated at 30 min if satisfactory analgesia was not achieve d. Side effects were recorded. A dose-response was demonstrated for bo th opioids. F 25 mu g and S 5 mu g were ineffective, with significantl y fewer women achieving VAS scores <10 mm (P < 0.05 compared with F 10 0 or 200 mu g and S 20 or 30 mu g). F 100 and 200 mu g and S 20 and 30 mu g all achieved VAS scores <10 mm in all women with no differences in time to 50% reduction in VAS (mean 11-16 min) and no differences in duration of analgesia (mean 117-138 min). The 50% and 95% effective d ose values for each opioid to achieve a VAS score <10 mm were F 33 mu g and 92 mu g and S 6.7 mu g and 17.5 mu g. There were no differences among groups in sedation scores or side effects. Our data suggest that the relative analgesic potency of epidural S:F is approximately 5 and that there are no differences between the opioids in the onset, durat ion, and effectiveness of analgesia when equianalgesic doses are admin istered postoperatively after lidocaine anesthesia for C/S.