Minimum Effective Volume of Liposomal Bupivacaine for Interscalene Block in Arthroscopic Rotator Cuff Repair: A Prospective, Biased-Coin Up-and-Down Dose-Finding Study.

BACKGROUND

Establishing the minimum effective volume (MEV90) of liposomal bupivacaine for ultrasound‑guided interscalene brachial plexus block (ISB) is essential to optimize postoperative analgesia and minimize local anesthetic-related side effects in patients undergoing arthroscopic rotator cuff repair. Determining this optimal volume provides a clinically meaningful reference for achieving consistent nerve block success while reducing unnecessary drug exposure and the risk of systemic toxicity. Therefore, the present study aimed to identify the MEV90 of liposomal bupivacaine for ISB in patients undergoing arthroscopic shoulder surgery.

PATIENTS AND

METHODS

This dose-finding study enrolled 51 patients scheduled for arthroscopic rotator cuff repair. Using a biased-coin up-and-down sequential design, patients received varying volumes of liposomal bupivacaine for ultrasound-guided ISB. The MEV90 was determined using centered isotonic regression. The occurrence of adverse events was systematically recorded for 72 hours.

RESULTS

The MEV90 of liposomal bupivacaine for ISB was 10.0mL (90% CI, 9.3 to 12.5mL). A moderate positive correlation was identified between the time to first analgesic request and the volume of liposomal bupivacaine administered (r = 0.6, P < 0.001). Adverse events within 72 hours following the block included dizziness (7.8%), nausea and vomiting (9.8%), and chest discomfort (3.9%).

CONCLUSION

The MEV90 of liposomal bupivacaine for ultrasound-guided interscalene brachial plexus block in patients undergoing rotator cuff repair surgery was found to be 10.0 mL.