Epidural sufentanil for postoperative analgesia: dose-response in patients recovering from major gynecologic surgery

To determine the lowest effective dose of epidural sufentanil given for analgesia, 41 patients undergoing elective abdominal gynecologic surgery during continuous epidural anesthesia (lidocaine 2%) were randomly assigned to one of four postoperative treatment groups. Patients received an epidural bolus of either 25 (group A), 40 (group B), 55 (group C), or 70 micrograms (group D) sufentanil in 10 mL of saline. They were evaluated for the next 8 h using a 10-cm visual analogue scale. Except for two individuals in group A, all patients achieved a visual analogue scale score of 1 cm or less during the study interval. The onset of analgesia was most rapid in the two higher dose groups (A vs C and D; P less than 0.05). Pairwise comparison between groups showed a significant difference in the time needed to achieve maximum pain relief between the lowest and highest treatment groups (A vs D; P less than 0.05). Duration of analgesia was also significantly longer in groups C and D than in group A (208.0 +/- 21.1 and 224.0 +/- 14.7 vs 140.0 +/- 10.7 min; P less than 0.05). There were no differences among groups with regard to mean respiratory rate, level of sedation, 24-h narcotic requirements, or incidence of nausea, vomiting, and pruritus (P = NS). A single patient in group D suffered profound respiratory depression within seconds of administration. We conclude that, in patients recovering from lower abdominal surgery, a single 40-55-micrograms epidural bolus of sufentanil provides 3-3.5 h of effective analgesia, and that larger doses are not warranted.