Butorphanol decreased the median effective concentration of ropivacaine in ultrasound-guided interscalene brachial plexus block.

Study Summary

50 patients undergoing arthroscopic shoulder surgery were randomized to receive ultrasound-guided interscalene brachial plexus block (ISB) with ropivacaine alone or ropivacaine combined with 1 mg of butorphanol. Ropivacaine concentration was adjusted sequentially using Dixon’s up-and-down method according to the preceding patient’s block response. The primary outcome of interest was the median effective concentration (EC50) of ropivacaine required for successful ISB. Secondary outcomes included ropivacaine dose, postoperative pain measured using the visual analogue scale (VAS), rescue analgesia, haemodynamic parameters, and adverse reactions. Outcomes were assessed during block performance and up to 24 hours postoperatively. Overall, the results of the study revealed that adding butorphanol reduced the EC50 and total dose of ropivacaine, while lowering VAS scores at 8 and 12 hours and reducing rescue analgesia requirements. These findings suggested that butorphanol may allow effective ISB using a lower concentration of ropivacaine while improving early postoperative analgesia.