Effective Dose of Epidural Hydromorphone for Analgesia Following Caesarean Section in Using Modified Dixon Sequential Method

Background: A single dose of epidural hydromorphone has been suggested as an alternative method for providing analgesia after caesarean section (CS). Nevertheless, the optimal dosage of epidural hydromorphone for postoperative pain relief following CS has yet to be determined.

Methods: This trial included 30 singleton primiparous women undergoing scheduled caesarean delivery, who were recruited to determine doses of epidural hydromorphone using the modified Dixon sequential method. The initial hydromorphone dose was 0.75 mg, with adjustments based on the efficacy of the preceding participant's dose over 12 hours. Various parameters such as blood pressure, heart rate, respiratory rate, visual analog scale (VAS) pain score, postoperative adverse reactions, and patient satisfaction with analgesic effect were recorded at each time point. The VAS scores were categorized as positive (score >3) or negative (score ≤3). Participants received a single epidural injection of 0.2% ropivacaine 20 mg along with a study dose of hydromorphone. The median effective dose (ED50), 90% effective dose (ED90), and corresponding 95% confidence intervals (CIs) of hydromorphone with ropivacaine for analgesia after caesarean section were calculated using the probit method.

Results: The ED90 and ED50 in our population were 1.105 mg (95% CI: 0.825-2.324 mg) and 0.659 mg (95% CI: 0.434-0.883 mg), respectively.

Conclusion: Epidural hydromorphone can be safely used for postoperative analgesia in patients undergoing caesarean section, and the analgesic effect is satisfactory when the dosage is appropriate.