External Oblique Intercostal Plane Block for Postoperative Analgesia After Major Upper Abdominal Surgery

External Oblique Intercostal Plane Block for Postoperative Analgesia After Major Upper Abdominal Surgery: A Randomized Controlled Trial

Postoperative pain after laparoscopic major upper abdominal surgery (e.g., gastric, hepatic, gallbladder, pancreatic surgery) is often severe, and inadequate analgesia may lead to increased opioid use, opioid dependence, and poor functional recovery. Current analgesic techniques such as neuraxial block have safety concerns (e.g., hypotension, neurological injury), while transversus abdominis plane (TAP) block is ineffective for blocking the lateral cutaneous branches of intercostal nerves in the upper abdomen. The External Oblique Intercostal Plane Block (EOIB) is a novel regional block technique that has shown promise in reducing postoperative opioids and pain in small-scale studies, but evidence for its use in major upper abdominal surgery is limited. This randomized controlled trial (RCT) aims to evaluate the analgesic efficacy and safety of bilateral EOIB combined with standard multimodal analgesia versus standard multimodal analgesia alone in patients undergoing elective laparoscopic major upper abdominal surgery. The primary outcome is the total postoperative opioid consumption (measured as Morphine Milligram Equivalents, MME) within 24 hours. Secondary and additional outcomes include pain scores (Verbal Rating Scale, VRS), recovery quality (QoR-15 scale), incidence of adverse events, and hospital stay.

Study Overview

• Status: Recruiting
• Conditions: Postoperative Pain; Abdominal Surgery
• Intervention / Treatment: Procedure: External Oblique Intercostal Plane Block; Other: Standard multimodal analgesia

Detailed Description

Postoperative pain after major upper abdominal surgery is common and may delay recovery and increase opioid-related adverse effects. The External Oblique Intercostal Plane Block (EOIB) is a novel fascial plane block intended to improve analgesia for upper abdominal incisions.

This study is a prospective, single-center, randomized, assessor-blinded controlled trial in adults (18-85 years, ASA I-III) scheduled for elective major upper abdominal laparoscopic-assisted surgery (e.g., gastric, hepatic, gallbladder, pancreatic procedures) with expected operative time ≥2 hours and planned use of IV patient-controlled analgesia (PCA). Participants will be randomized 1:1 using a computer-generated, variable block-size sequence with allocation concealment via opaque sealed envelopes. The block-performing anesthesiologist will not collect outcomes; outcome assessors will be blinded to group assignment.

After induction of general anesthesia and before surgical incision, patients in the intervention group will receive ultrasound-guided bilateral EOIB at the 6th rib level using an in-plane technique; 15 mL per side of a mixture of 0.75% ropivacaine and normal saline will be injected. Control participants will receive no regional block. All participants will receive standardized multimodal analgesia including IV PCA, antiemetic prophylaxis (dexamethasone 5 mg; ondansetron as needed), and NSAID use per ERAS practice.

The primary endpoint is total opioid consumption during the first 24 hours after surgery, expressed as IV morphine milligram equivalents (MME), including PCA and rescue opioids. Secondary outcomes include postoperative pain scores (0-10 verbal rating scale) at prespecified time points (including 24, 48, and 72 hours; at rest and with activity as applicable), quality of recovery (QoR-15 at 24/48/72 hours), opioid consumption at 24-48 hours, postoperative nausea and vomiting within 72 hours, intraoperative hemodynamic events, time to first flatus, and postoperative length of stay.

• Study Type: Interventional
• Enrollment (Estimated): 78
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Jun Zhang, PhD; Phone Number: 0216417559001; Email: snapzhang@aliyun.com

Study Locations

• China
  • Shanghai, China
    • Recruiting
    • Fudan University Shanghai Cancer Center
    • Contact: Jun Zhang Fudan University Shanghai Cancer Center; Phone Number: 13817153025; Email: snapzhang@aliyun.com

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Obtain written informed consent from participants or their legal representatives
• Age between 18 and 85 years
• American Society of Anesthesiologists (ASA) physical status classification I-III
• Scheduled for elective laparoscopic major upper abdominal surgery (e.g., gastric, hepatic, gallbladder, pancreatic surgery)
• Expected surgical duration ≥ 2 hours
• Ability to use the intravenous patient-controlled analgesia (IV PCA) system

Exclusion Criteria:

• Hepatic disease (liver enzyme levels ≥ 2× the upper limit of normal)
• Renal disease (serum creatinine levels ≥ 2× the upper limit of normal)
• Allergy to local anesthetics or known study-related drugs
• Pregnancy or lactation
• Low surgical incision site (not involving the upper abdominal wall innervated by T6-T10 nerves)
• Coagulopathy or current use of anticoagulant medications
• Opioid use for more than 2 weeks in the past 6 months

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Double

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: EOIB Block; Participants receive ultrasound-guided bilateral External Oblique Intercostal Plane Block (EOIB) after induction of general anesthesia and before surgical incision, using ropivacaine (15 mL per side), in addition to standard multimodal analgesia (including IV PCA and ERAS-based non-opioid analgesics).	Procedure: External Oblique Intercostal Plane Block; Ultrasound-guided bilateral external oblique intercostal plane block (EOIB) performed after induction of general anesthesia and before surgical incision. Using an in-plane technique at the 6th rib level, 15 mL per side of local anesthetic solution (ropivacaine 0.75% diluted with normal saline) is injected between the external oblique muscle and the intercostal muscle. Standard multimodal analgesia is also provided to all participants.; Other Names: EOIB
Sham Comparator: Usual Analgesia; Participants receive standard multimodal analgesia without any regional block. Analgesia includes IV patient-controlled analgesia (PCA) and other non-opioid analgesics per the institutional ERAS protocol.	Other: Standard multimodal analgesia; Standard multimodal analgesia per institutional ERAS practice, including intravenous patient-controlled analgesia (IV PCA) with opioids and adjunct non-opioid analgesics (e.g., NSAIDs and/or acetaminophen) with antiemetic prophylaxis as needed. No regional block is administered.; Other Names: Usual analgesia

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Total opioid consumption within 24 hours after surgery (IV morphine milligram equivalents, MME)	Cumulative postoperative opioid use from end of surgery to 24 hours postoperatively, including IV PCA opioids and any rescue opioids, converted to intravenous morphine milligram equivalents (MME) and reported in mg.	0-24 hours postoperatively (from end of surgery to 24 hours after surgery)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Postoperative Pain Score Within 24 Hours Postoperatively	Pain is assessed using a Verbal Rating Scale (VRS) with scores ranging from 0 (no pain) to 10 (worst pain imaginable). Assessments are performed each morning and evening. A difference of ≥1 point between groups is considered clinically significant.	Within 24 hours postoperatively
Postoperative Recovery Quality at 24 Hours Postoperatively	Recovery quality is evaluated using the QoR-15 scale (a 15-item questionnaire measuring physical comfort, emotional state, and functional recovery). A difference of ≥6 points between groups is considered clinically significant.	24 hours postoperatively

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Opioid Consumption (Morphine Milligram Equivalents, MME) Within 24-48 Hours Postoperatively	Total opioid consumption includes doses from intravenous patient-controlled analgesia (IV PCA) and rescue analgesics, converted to Morphine Milligram Equivalents (MME). A reduction of ≥10 mg MME between groups is considered clinically significant.	25-48 hours postoperatively
Postoperative Pain Score Postoperatively	Pain is assessed using a Verbal Rating Scale (VRS) with scores ranging from 0 (no pain) to 10 (worst pain imaginable). Assessments are performed each morning and evening. A difference of ≥1 point between groups is considered clinically significant.	25~72 hours postoperatively
Postoperative Recovery Quality Postoperatively	Recovery quality is evaluated using the QoR-15 scale (a 15-item questionnaire measuring physical comfort, emotional state, and functional recovery). A difference of ≥6 points between groups is considered clinically significant.	25~72 hours postoperatively
Incidence of Nausea and Vomiting Postoperatively	The number of patients experiencing nausea or vomiting is recorded, stratified by four time periods: 1-6 hours, 7-24 hours, 25-48 hours, and 49-72 hours postoperatively.	Within 72 hours postoperatively (stratified by 1-6h, 7-24h, 25-48h, 49-72h)
Intraoperative Incidence of Hypotension and Hypertension	Intraoperative hypotension is defined as systolic blood pressure <90 mmHg or a 30% reduction from baseline; intraoperative hypertension is defined as systolic blood pressure >160 mmHg or a 30% increase from baseline. The incidence of both conditions is recorded.	Intraoperatively (during surgery)
Time to First Flatus Postoperatively	The duration from surgery completion to the patient's first flatus is recorded as an indicator of gastrointestinal function recovery.	From surgery completion to first flatus (up to 72 hours postoperatively)
Postoperative Hospital Stay Duration	The duration from surgery completion to hospital discharge is recorded.	From surgery completion to hospital discharge (typically 3-7 days postoperatively)

Collaborators and Investigators

• Sponsor: Jun Zhang
• Investigators: Study Director: Jun Zhang, PhD, Fudan University

Study record dates

Study Major Dates

• Study Start (Actual): February 1, 2026
• Primary Completion (Estimated): August 20, 2026
• Study Completion (Estimated): August 31, 2026

Study Registration Dates

• First Submitted: December 28, 2025
• First Submitted That Met QC Criteria: December 28, 2025
• First Posted (Actual): January 9, 2026

Study Record Updates

• Last Update Posted (Actual): May 27, 2026
• Last Update Submitted That Met QC Criteria: May 24, 2026
• Last Verified: May 1, 2026

More Information

Terms related to this study

• Keywords: Postoperative Pain; Randomized Controlled Trial; Pain Management; Laparoscopic Surgery; External Oblique Intercostal Plane Block
• Additional Relevant MeSH Terms: Pain; Neurologic Manifestations; Nervous System Diseases; Postoperative Complications; Pathologic Processes; Neurobehavioral Manifestations; Perceptual Disorders; Pathological Conditions, Signs and Symptoms; Signs and Symptoms; Pain, Postoperative; Agnosia
• Other Study ID Numbers: 2512335-12

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No