Liposomal Bupivacaine for Serratus Anterior Plane Block in Modified Radical Mastectomy: Protocol for a Randomized,...

Modified radical mastectomy is commonly associated with substantial postoperative pain, opioid use and impaired early recovery. Serratus anterior plane block (SAPB) is increasingly used as part of multimodal analgesia for breast surgery. Although SAPB and quality of recovery outcomes have both been studied in breast surgery, published evidence regarding the use of liposomal bupivacaine in SAPB for modified radical mastectomy remains limited. This trial was designed to address whether adding liposomal bupivacaine to bupivacaine hydrochloride (bupivacaine HCl) for SAPB improves pain-related and early recovery outcomes after surgery.

This is a prospective, randomized, double-blind, controlled trial. Seventy-six patients undergoing elective modified radical mastectomy for breast cancer are being randomly assigned in a 1:1 ratio to receive unilateral ultrasound-guided SAPB after induction of general anesthesia and before skin incision with either liposomal bupivacaine plus bupivacaine HCl (Group L) or bupivacaine HCl alone (Group B). The primary endpoint is the Quality of Recovery-15 (QoR-15) score at 24 h postoperatively. Secondary outcomes include postoperative pain intensity up to 72 h, opioid-related outcomes expressed as morphine milligram equivalents (MME), QoR-15 scores at 48 and 72 h, time to first demand of patient-controlled analgesia (PCA), Overall Benefit of Analgesia Score (OBAS), postoperative nausea and vomiting, sleep quality, perioperative complications and patient-reported neuropathic pain symptoms at 3 months assessed using the Douleur Neuropathique 4 interview (DN4i). The primary analysis will follow the intention-to-treat (ITT) principle. Prespecified sensitivity analyses will include a modified ITT (mITT) set excluding participants who did not receive the allocated SAPB injection and an exploratory per-protocol (PP) set excluding major protocol deviations.

This trial will evaluate whether adding liposomal bupivacaine to bupivacaine HCl for SAPB provides additional benefit for pain-related and early recovery outcomes after modified radical mastectomy compared with SAPB using bupivacaine HCl alone.

Chinese Clinical Trial Registry, Registration No. ChiCTR2500111732. Registered on 5 November 2025.