Intrathecal hydromorphone added to hyperbaric bupivacaine for postoperative pain relief after knee arthroscopic surgery: A prospective, randomised, controlled trial

Background and objective: Adding opioid to spinal anaesthetic provides additional analgesia during the postoperative period. The purpose of this study was to determine the dose of intrathecal hydromorphone necessary to achieve postoperative pain relief after arthroscopic knee surgery. Methods: In a prospective, double-blinded parallel, placebocontrolled manner, 60 patients who were undergoing unilateral knee arthroscopy randomly received unilateral spinal anaesthesia with 0.5% hyperbaric bupivacaine 6mg combined with 0.0, 2.5, 5.0 or 10.0μg per 0.05ml hydromorphone. Fifteen patients were assigned to receive each dose. The visual analogue pain scores (VAPSs) were measured at 30 min and 2, 4, 6, 12 and 24h postoperatively, and the side-effects of hydromorphone were recorded. Results: The postoperative VAPSs at 4, 6 and 12h for the 5 and 10mg hydromorphone groups were significantly decreased, compared to the control group. The 2.5 μg hydromorphone group had lower VAPS only at 4 and 6h postoperatively. Nausea was significantly increased in the 10 μg hydromorphone group (46.6%). Conclusion: The analgesic effects of 5 and 10 μg intrathecal hydromorphone provided satisfactory pain relief for 12h postoperatively and nausea increased significantly in a dosedependent manner.