Two Bupivacaine Concentrations for Rectus Intercostal Fascial Plane Block After Laparoscopic Cholecystectomy

Pain after laparoscopic cholecystectomy remains clinically relevant, and current recommendations favour multimodal, opioid-sparing analgesia including regional techniques. The rectus intercostal fascial plane block (RIFPB) is a recently described technique in which local anesthetic is injected into the plane between the rectus abdominis muscle and the 6th and 7th costal cartilages, targeting the anterior and lateral cutaneous branches of the sixth to ninth thoracic (T6-T9) thoracoabdominal nerves.

In the investigators' previous randomized controlled trial, bilateral RIFPB after laparoscopic cholecystectomy significantly reduced the need for rescue analgesia (17.9% versus 55.3%) and pain scores during the first 12 postoperative hours. That trial used 30 mL of 0.25% bupivacaine per side (60 mL, 150 mg in total), a dose approaching the recommended upper limit, and whether lower doses provide comparable analgesia remains unknown. Because fascial plane blocks depend on local anesthetic spread, large volumes are preferred, increasing the total dose and the risk of local anesthetic systemic toxicity (LAST); lowering the concentration as volume increases has therefore been recommended. Equal-volume studies of transversus abdominis plane and erector spinae plane blocks suggest that lower concentrations provide comparable analgesia, but no study has compared concentrations for RIFPB.

This trial will compare, at a fixed volume of 30 mL per side (60 mL in total), bilateral RIFPB with 0.25% bupivacaine, bilateral RIFPB with 0.125% bupivacaine, and routine port-site infiltration without a block (control) in adults undergoing elective laparoscopic cholecystectomy under general anesthesia. Ninety patients will be randomly allocated in a 1:1:1 ratio.

The primary outcome is total rescue tramadol consumption during the first 24 postoperative hours. Secondary outcomes include numeric rating scale (NRS) pain scores at rest and on movement, the need for and time to first rescue analgesia, nausea, vomiting and pruritus, block-related complications and signs of LAST, patient satisfaction, and length of hospital stay.

The investigators hypothesize that RIFPB at either concentration will reduce analgesic consumption and pain scores compared with control, and that the lower concentration will provide comparable analgesia while halving the total bupivacaine dose (75 mg instead of 150 mg), thereby reducing the risk of LAST.