Ultrasound-guided external oblique intercostal plane block with ropivacaine for analgesia after open hepatectomy- a randomized controlled study

Background: The external oblique intercostal (EOI) plane block has been proposed as an innovative regional anesthetic technique for upper abdominal surgery by recent case reports. This randomized controlled study evaluated whether ultrasound-guided EOI plane block improves analgesia compared with patient-controlled intravenous analgesia (PCIA) alone in patients undergoing open hepatectomy. Methods: Between July 24, 2023 and May 29, 2024, 70 adult patients scheduled for elective open hepatectomy at Zhongshan Hospital, Fudan University, were randomly assigned (1:1) to receive an EOI plane block with ropivacaine 0.375% (30 ml) or the equivalent 0.9% normal saline, in addition to PCIA. The primary outcome was opioid consumption in intravenous (IV) morphine equivalents within 24 h postoperatively. Secondary outcomes included opioid consumption at 1, 8, 12, 36, and 48 h postoperatively; visual analogue scale (VAS) pain scores at rest and during coughing at 12, 24, and 48 h postoperatively; intraoperative opioid use; time to first postoperative rescue analgesia; pruritus; nausea or vomiting; EOI-related complications; QoR-15 at 24 and 48 h; length of hospital stay, and chronic pain at 3 months. Results: The EOI group showed significantly lower opioid consumption in IV morphine equivalents at 24 h postoperatively (mean difference=-2.91, P=0.019), with greater reduction at 36 h (-4.66 mg), and 48 h (-6.06 mg, both P<0.001) postoperatively. The EOI group also required less intraoperative fentanyl, reported lower resting VAS pain scores, and had a longer time to first postoperative rescue analgesia. No significant between-group differences were observed in coughing pain scores, QoR-15, length of stay, or chronic pain. No complications related to EOI were detected. Conclusions: Preoperative EOI plane block reduced intraoperative and postoperative opioid consumption and improve pain control after open hepatectomy compared to PCIA alone without block-related complications.