EOI Block vs. TAP Block in Minimally Invasive Hepatectomy (EOIvsTAP)

External Oblique Intercostal Plane Block and Subcostal Transversus Abdominis Plane Block in Minimally Invasive Hepatectomy: Non-inferiority Trial

This study aims to compare the analgesic efficacy of two different ultrasound-guided nerve blocks-the External Oblique Intercostal (EOI) block and the Subcostal Transversus Abdominis Plane (TAP) block-in patients undergoing minimally invasive hepatectomy. All participants will receive standardized general anesthesia and perioperative care at Seoul National University Hospital. Following anesthesia induction, patients will be randomly assigned to receive either an EOI block or a subcostal TAP block with 0.375% ropivacaine to provide regional pain relief. Postoperative pain will be managed using a combination of scheduled non-opioid analgesics and a fentanyl-based patient-controlled analgesia (PCA) device. The primary objective is to evaluate which regional technique more effectively reduces cumulative opioid consumption during the first 24 hours after surgery. Additionally, the study will assess pain intensity using the Numerical Rating Scale (NRS), the incidence of postoperative nausea and vomiting, and the overall recovery profile, including the time to first ambulation.

Study Overview

• Status: Not yet recruiting
• Conditions: Hepatectomy
• Intervention / Treatment: Procedure: External Oblique Intercostal Block; Procedure: TAP Block

Detailed Description

[Anesthesia and Induction] Except for the specific nerve block technique assigned to each group, all participants will receive the standard anesthetic care for minimally invasive hepatectomy at Seoul National University Hospital. No premedication will be administered before entering the operating room, where standard non-invasive monitoring will be established. Anesthesia will be induced with remifentanil target-controlled infusion, propofol, and rocuronium after loss of consciousness. Endotracheal intubation will be performed after neuromuscular blockade. Anesthesia will be maintained with desflurane and remifentanil infusion, adjusted according to clinical requirements. As a part of the perioperative care, palonosetron (0.075 mg) and dexamethasone (5 mg) will be given intravenously during induction for antiemetic prophylaxis, and intravenous acetaminophen (1 g) and nefopam (20 mg) will be administered before the start of surgery. [Interventional Procedures] Following the induction of anesthesia, all nerve blocks will be performed under ultrasound guidance using a high-frequency convex probe covered with a sterile sheath under aseptic conditions. For the External Oblique Intercostal (EOI) block group, the T10 rib will be located at the intersection of the midclavicular line and the umbilical line, and the clinician will count upwards to identify the T6, T7, and T8 ribs. The probe will then be placed perpendicular to the rib trajectory at the T6-7 or T7-8 intercostal space to identify the external intercostal plane. Using an in-plane approach with an 8-cm needle, the plane will be confirmed via hydrodissection with 1-2 mL of saline, followed by the bilateral injection of 20 mL of 0.375% ropivacaine per side (total 40 mL). In contrast, for the Subcostal Transversus Abdominis Plane (TAP) block group, the probe will be placed on the subxiphoid midline and moved laterally along the T12 rib to identify the transversus abdominis plane. The needle will be advanced to the plane between the internal oblique and transversus abdominis muscles, and similarly, 20 mL of 0.375% ropivacaine will be injected into each side (total 40 mL) after confirming the plane with saline. [Postoperative Analgesia and Outcomes] Postoperative pain will be managed primarily using a fentanyl-based patient-controlled analgesia (PCA) device (Accumate 1200, Woo Young Medical), set with a loading dose of 50 mcg, a demand-only bolus of 20 mcg, and a 10-minute lockout time without basal infusion. A scheduled non-opioid regimen, consisting of intravenous acetaminophen (1 g) and nefopam (20 mg) every 8 hours, will be maintained for 48 hours, transitioning to oral acetaminophen (650 mg) once oral intake resumes. In the Post-Anesthesia Care Unit (PACU), if a patient reports a Numerical Rating Scale (NRS) score of 7 or higher despite active PCA use (exceeding four times per hour), a rescue dose of 50 mcg of intravenous fentanyl will be provided.

• Study Type: Interventional
• Enrollment (Estimated): 140
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Hyun-Kyu Yoon; Phone Number: +82-2-2072-2467; Email: warren83@snu.ac.kr
• Study Contact Backup: Name: wooyoung jo; Phone Number: 01079333021; Email: jowoo345@naver.com

Study Locations

• South Korea
  • Seoul, South Korea, 03080
    • SNUH
    • Contact: Hyun-Kyu Yoon; Phone Number: +82-2-2072-2467; Email: warren83@snu.ac.kr

Participation Criteria

Eligibility Criteria

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

Description

Inclusion Criteria:

Scheduled to undergo elective robotic or laparoscopic minimally invasive hepatectomy

Exclusion Criteria:

• American Society of Anesthesiologists physical status IV or higher
• History of chronic pain or current use of analgesics, antidepressants, or anticonvulsants for pain management
• Known hypersensitivity to general anesthetics, opioids, or local anesthetics
• Conversion to open hepatectomy
• Requirement for mechanical ventilation for more than 2 hours within 48 hours postoperatively
• Any other clinical condition that makes the patient unsuitable for participation in the study.

Study Plan

How is the study designed?

Design Details

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

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: External Oblique Intercostal (EOI) block group; patients who receive EOI block	Procedure: External Oblique Intercostal Block; Following the induction of general anesthesia, patients in this group will receive an ultrasound-guided bilateral external intercostal fascial plane block. A total of 40 mL of 0.375% ropivacaine (20 mL per side) will be injected into the plane between the external intercostal muscle and the internal intercostal muscle at the T6-7 or T7-8 level.
Active Comparator: Transversus Abdominis Plane (TAP) block group; Patients who receive TAP block	Procedure: TAP Block; Following the induction of general anesthesia, patients in this group will receive an ultrasound-guided bilateral subcostal transversus abdominis plane block. A total of 40 mL of 0.375% ropivacaine (20 mL per side) will be injected into the fascial plane between the internal oblique and transversus abdominis muscles along the subcostal margin.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Cumulative opioid consumption at 24 hours postoperatively	The total amount of intravenous fentanyl administered via patient-controlled analgesia (PCA) and as rescue boluses will be recorded and converted to intravenous morphine equivalents for standardized comparison.	From the end of surgery up to 24 hours postoperatively

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Cumulative Opioid Consumption at 1, 6, 12, and 48 hours postoperatively	Total amount of fentanyl administered via IV-PCA and rescue boluses. All doses will be recorded and analyzed at each specified time point.	1, 6, 12, and 48 hours after surgery completion.
Postoperative pain intensity measured by Numerical Rating Scale (NRS)	Pain intensity is assessed using a scale from 0 to 10, where 0 indicates "no pain" and 10 indicates "the worst pain imaginable."	During Post-Anesthesia Care Unit (PACU) stay, and at 24 and 48 hours postoperatively.
Total dose of intraoperative remifentanil	Total administered dose of intraoperative remifentanil (mcg) measured from anesthesia induction to skin closure.	During the intraoperative period (from induction to skin closure).
Incidence of Postoperative Nausea and Vomiting	The presence or absence of postoperative nausea and vomiting episodes (dichotomous outcome: yes/no) will be recorded.	Up to 48 hours postoperatively.
Time to first ambulation	The time interval (hours) from the end of surgery until the patient first successfully achieves independent or assisted walking.	From the end of surgery up to 48 hours postoperatively (or until the first occurrence).

Collaborators and Investigators

• Sponsor: Seoul National University Hospital
• Investigators: Study Chair: Hyun-Kyu Yoon, MD/PhD, Seoul National University Hospital

Study record dates

Study Major Dates

• Study Start (Estimated): June 1, 2026
• Primary Completion (Estimated): May 31, 2027
• Study Completion (Estimated): June 30, 2027

Study Registration Dates

• First Submitted: May 22, 2026
• First Submitted That Met QC Criteria: May 22, 2026
• First Posted (Actual): May 29, 2026

Study Record Updates

• Last Update Posted (Actual): June 8, 2026
• Last Update Submitted That Met QC Criteria: June 4, 2026
• Last Verified: June 1, 2026

More Information

Terms related to this study

• Keywords: TAP block; EOI block; minimally invasive hepatectomy
• Other Study ID Numbers: 2512-081-1703

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: Deidentified individual participant data and a data dictionary will be made available to researchers for specified analyses upon reasonable request to the corresponding author via email.

Drug and device information, study documents

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