Comparison of M-TAPA and External Oblique Intercostal Block for Intraoperative Opioid Consumption in Laparoscopic Cholecystectomy (MTAPA-EOI)

Comparison of M-TAPA and External Oblique Intercostal Plane Block on Intraoperative Analgesia and Opioid Consumption Guided by Skin Conductance Algesimeter in Laparoscopic Cholecystectomy

This prospective observational study is designed to evaluate the effects of modified thoracoabdominal nerve block through perichondrial approach (M-TAPA) and external oblique intercostal (EOI) plane block on intraoperative analgesia and opioid consumption in patients undergoing elective laparoscopic cholecystectomy. Abdominal wall blocks are widely used to improve perioperative analgesia; however, their impact on intraoperative opioid requirements when guided by objective nociception monitoring remains unclear.

All patients will receive standardized general anesthesia. Intraoperative analgesia will be guided using the Skin Conductance Algesimeter (SCA), which reflects sympathetic nervous system activity by measuring fluctuations in skin conductance. The SCA parameter "peaks per second (PPS)" will be used to assess nociceptive responses. Remifentanil infusion will be titrated according to SCA values to maintain adequate analgesia. Dose adjustments will be performed at predefined intervals, and changes will be considered valid only if sustained for a minimum duration.

Patients will receive either M-TAPA or EOI block as part of routine clinical practice. The choice of block will not be influenced by the investigators, in accordance with the observational design of the study. Data will be collected prospectively during the intraoperative period and postoperative follow-up.

The primary outcome of the study is the time-weighted average intraoperative remifentanil infusion rate (µg/kg/min). Secondary outcomes include total intraoperative remifentanil consumption (µg/kg), intraoperative hemodynamic parameters (heart rate and mean arterial pressure), frequency of deviations in SCA values from the target range, postoperative pain scores assessed using a numeric rating scale (NRS), time to first analgesic requirement, and total rescue analgesic consumption.

Perioperative analgesia will be standardized. All patients will receive intravenous dexketoprofen toward the end of surgery as part of routine clinical practice. Rescue analgesia will be provided with intravenous dexketoprofen when clinically indicated. Additional outcomes include postoperative nausea and vomiting and perioperative complications.

This study aims to provide objective data on the opioid-sparing effects of different abdominal wall block techniques when intraoperative analgesia is guided by nociception monitoring. The findings may contribute to optimizing analgesic strategies and improving perioperative pain management in laparoscopic surgery.

Study Overview

• Status: Not yet recruiting
• Conditions: Perioperative Analgesia; Laparoscopic Cholecystectomy Surgery

Detailed Description

This prospective observational study evaluates intraoperative opioid requirements under nociception-guided analgesia in patients undergoing elective laparoscopic cholecystectomy. Analgesic management is guided by the Skin Conductance Algesimeter (SCA), which reflects sympathetic activation through fluctuations in palmar skin conductance. The SCA-derived parameter "peaks per second (PPS)" is used as a real-time surrogate of nociceptive activity.

General anesthesia is administered according to institutional standards. Remifentanil is delivered via continuous infusion and titrated in response to SCA values to maintain a predefined nociception-analgesia balance. Dose adjustments are performed in stepwise increments, with changes considered valid only if sustained over a defined period. Hemodynamic variables are monitored concurrently but are not the primary determinants of opioid titration.

Abdominal wall analgesia is provided using either modified thoracoabdominal nerve block through perichondrial approach (M-TAPA) or external oblique intercostal (EOI) plane block, both applied as part of routine clinical practice. In line with the observational design, no allocation or intervention is performed by the investigators, and block selection is based on standard clinical decision-making.

Intraoperative data are recorded at fixed time intervals, including heart rate, mean arterial pressure, SCA-derived PPS values, and remifentanil infusion rates. The primary endpoint is the time-weighted average remifentanil infusion rate (µg/kg/min), reflecting overall intraoperative opioid requirement normalized to surgical duration. Secondary analyses include total opioid exposure, frequency and magnitude of deviations from target nociception ranges, and perioperative analgesic requirements.

Intravenous dexketoprofen is administered toward the end of surgery as part of routine clinical care. Postoperative outcomes include pain intensity assessed using a numeric rating scale (NRS), time to first analgesic request, and additional analgesic consumption. Postoperative nausea, vomiting, and perioperative adverse events are also recorded.

This study aims to characterize the relationship between nociception-guided opioid titration and regional anesthesia techniques, and to determine the relative contribution of abdominal wall blocks to intraoperative opioid sparing under objective monitoring conditions.

• Study Type: Observational
• Enrollment (Estimated): 80

Contacts and Locations

• Study Contact: Name: İsmet Uluhan, MD; Phone Number: +905077128389; Email: ismtptlk@gmail.com

Participation Criteria

Eligibility Criteria

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

• Sampling Method: Non-Probability Sample

Study Population

Adult patients undergoing elective laparoscopic cholecystectomy under general anesthesia at a tertiary care hospital.

Description

Inclusion Criteria:

• Patients aged 18-80 years
• ASA physical status I-III
• Scheduled for elective laparoscopic cholecystectomy under general anesthesia
• Ability to provide written informed consent

Exclusion Criteria:

• Patient refusal
• Known allergy to local anesthetics
• Chronic opioid use or opioid dependence
• Neurological or psychiatric disorders affecting pain perception
• Use of medications affecting autonomic nervous system activity, such as beta-blockers
• Infection at the injection site
• Coagulopathy or anticoagulant therapy
• Pregnancy

Study Plan

How is the study designed?

Number of groups / cohorts

2

Cohorts and Interventions

Group / Cohort
M-TAPA Group; Patients receiving ePatients receiving modified thoracoabdominal nerve block through perichondrial approach (M-TAPA) for intraoperative analgesia during laparoscopic cholecystectomy.ternal oblique intercostal plane block (EOI) for analgesia
EOI Group; Patients receiving external oblique intercostal plane (EOI) block for intraoperative analgesia during laparoscopic cholecystectomy.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Time-Weighted Mean Intraoperative Remifentanil Infusion Rate	The time-weighted mean intraoperative remifentanil infusion rate will be calculated throughout the surgical period and expressed as micrograms per kilogram per minute (µg/kg/min) based on continuous infusion data.	Intraoperative period (from induction to end of surgery)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Postoperative Pain Scores Assessed by Numeric Rating Scale	Postoperative pain intensity will be assessed using the Numeric Rating Scale (NRS), ranging from 0 to 10, where 0 indicates no pain and 10 indicates the worst imaginable pain. Higher scores indicate worse pain. Assessments will be performed at rest and during movement.	0, 2, 4, 6, 12, and 24 hours postoperatively
Time to First Analgesic Requirement	Time to First Analgesic Requirement	Within 24 hours postoperatively
Rescue Analgesic Consumption	Total amount of rescue analgesic (dexketoprofen) administered within the first 24 hours postoperatively.	First 24 hours postoperatively
Mean Arterial Pressure	Mean arterial pressure (MAP), expressed in mmHg, will be recorded intraoperatively and compared with baseline values.	Intraoperative period
Heart Rate	Heart rate, expressed as beats per minute, will be recorded intraoperatively and compared with baseline values.	Intraoperative period
Skin Conductance Algesimeter(SCA)	Skin Conductance Algesimeter (SCA) peaks per second (PPS) values recorded intraoperatively to assess nociceptive responses.	Intraoperative period
Postoperative Nausea and Vomiting (PONV)	Incidence of postoperative nausea and vomiting within the first 24 hours after surgery.	First 24 hours postoperatively

Collaborators and Investigators

• Sponsor: Ankara Etlik City Hospital

Publications and helpful links

General Publications

• Tulgar S, Selvi O, Thomas DT, Deveci U, Ozer Z. Modified thoracoabdominal nerves block through perichondrial approach (M-TAPA) provides effective analgesia in abdominal surgery and is a choice for opioid sparing anesthesia. J Clin Anesth. 2019 Aug;55:109. doi: 10.1016/j.jclinane.2019.01.003. Epub 2019 Jan 9. No abstract available.
• Elsharkawy H, Kolli S, Soliman LM, Seif J, Drake RL, Mariano ER, El-Boghdadly K. The External Oblique Intercostal Block: Anatomic Evaluation and Case Series. Pain Med. 2021 Nov 26;22(11):2436-2442. doi: 10.1093/pm/pnab296.
• Norbeck DW, Lindgren S, Wolf A, Jildenstal P. Reliability of nociceptive monitors vs. standard practice during general anesthesia: a prospective observational study. BMC Anesthesiol. 2025 Jan 31;25(1):51. doi: 10.1186/s12871-025-02923-4.

Study record dates

Study Major Dates

• Study Start (Estimated): May 15, 2026
• Primary Completion (Estimated): August 1, 2026
• Study Completion (Estimated): September 1, 2026

Study Registration Dates

• First Submitted: May 5, 2026
• First Submitted That Met QC Criteria: May 15, 2026
• First Posted (Actual): May 19, 2026

Study Record Updates

• Last Update Posted (Actual): May 19, 2026
• Last Update Submitted That Met QC Criteria: May 15, 2026
• Last Verified: May 1, 2026

More Information

Terms related to this study

• Keywords: Remifentanil; Laparoscopic Cholecystectomy; Opioid Consumption; M-TAPA; External Oblique Intercostal Block; Abdominal Wall Block; Skin Conductance Algesimeter; Intraoperative Analgesia
• Other Study ID Numbers: AEŞH-EK-2026-019

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: Individual participant data will not be shared in accordance with institutional policies

Drug and device information, study documents

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