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Updated: Jun 16, 2026

An Experimental Paradigm for the Prediction of Post-Operative Pain (PPOP)
Published on: January 27, 2010
Determination of the ED90 for Epidural Hydromorphone and Morphine for Postoperative Pain Using a Biased-Coin
Xiaolin Tang1, Yu Liang1, Yuting Hu1
1Department of Anaesthesiology, Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, People's Republic of China.
Background:
Hydromorphone and morphine are the primary opioids recommended for epidural analgesia following cesarean delivery. This study aimed to determine the 90% effective dose (ED90) of epidural hydromorphone and morphine in this patient population.
Methods:
In this dose-finding trial, 80 patients undergoing cesarean delivery under combined spinal-epidural anesthesia (CSEA) were randomized to receive a single epidural injection of either hydromorphone or morphine after uterine closure. The dose of each agent was determined using a biased-coin up-and-down sequential allocation method to estimate the ED90. In addition, all patients received standardized multimodal analgesia postoperatively. Satisfactory analgesia was defined as a visual analogue scale (VAS) score ≤3 within 12 hours after cesarean delivery, without the need for supplemental opioids.
Results:
The estimated ED90 was 500 µg (95% confidence interval [CI], 495.00-532.50 µg) for epidural hydromorphone and 3 mg (95% CI, 2.97-3.21 mg) for epidural morphine. Comparative analyses of postoperative VAS scores, adverse effects (nausea/vomiting and pruritus), and rescue hydromorphone consumption revealed no statistically significant differences between the two dosage groups.
Conclusion:
The ED90 for post-cesarean analgesia was estimated to be 500 µg for epidural hydromorphone and 3 mg for epidural morphine. There were no statistically significant differences in adverse effects between the two drugs at their respective ED90 doses.
Clinical Trial Registration:
ChiCTR2400084510.
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