Postoperative Analgesic Effects of Different Doses of Epidural Hydromorphone Coadministered with Ropivacaine after Cesarean Section: A Randomized Controlled Trial

PURPOSE: Single dose of epidural hydromorphone has been introduced to serve as an alternative method for postcesarean section analgesia. However, optimal dose of epidural hydromorphone remains unknown. Hence, we evaluated and compared the analgesic and adverse effects of postoperative different doses of epidural hydromorphone coadministered with ropivacaine after cesarean section. METHODS: Eighty term parturients with elective cesarean section under epidural anesthesia were allocated into four groups. Epidural analgesia was administered with an epidural bolus of either 0 mg (group H0), or 0.2 mg (group H1), or 0.4 mg (group H2), or 0.6 mg (group H3) hydromorphone coadministered with ropivacaine. The primary outcome was the visual analogue pain scores (VAPSs) and rescue opioid consumption (PCIA with sulfentanil) in 24 hours. Adverse effects such as respiratory depression, pruritus, nausea, and vomiting were recorded. RESULTS: The VAPSs of group H1 at 2, 4, 6, 12 h and 24 h after surgery was similar to group H0. The VAPSs of group H2 at 4 and 6 h postoperatively were significantly decreased when compared to group H0. But, the VAPSs of group H2 at 2, 12, and 24 h postoperatively were similar to those of group H0. The VAPSs of group H3 at 4, 6, 12 h, and 24 h after surgery were significantly decreased when compared to those of group H0. The total sulfentanil consumption in 24 hours was 90 ± 26 μg in group H0, 75 ± 29 μg in group H1, 54 ± 32 μg in group H2, and 15 ± 16 μg in group H0. Adverse effects were comparable in the four groups. CONCLUSIONS: Epidural administration of 0.6 mg hydromorphone coadministered with ropivacaine after cesarean section provided satisfactory pain relief with less sulfentanil consumption. This trial is registered with ChiCTR-IPR-16010026.