Opioid-Free Versus Opioid-Based Anesthesia in Bariatric

A Prospective, Randomized Controlled Trial Comparing Opioid-Free and Opioid-Based Anesthesia in Morbidly Obese Patients Undergoing Bariatric Surgery

This study is designed as a prospective, randomized, controlled clinical trial. It will be conducted in the operating rooms of the University of Health Sciences, Diyarbakır Gazi Yaşargil Training and Research Hospital. Patients aged 18 to 65 years who are scheduled for elective bariatric surgery and meet the inclusion criteria (ASA physical status I-III) will be enrolled in the study.

Eligible patients will be informed both verbally and in writing during their preoperative anesthetic evaluation, and written informed consent will be obtained at least 24 hours prior to surgery.

Patients will be randomly assigned to one of two groups using computer-generated randomization:

Group O (Opioid group)

Group NO (Opioid-free group)

All patients will receive 40 mg IV pantoprazole and 4 mg IV ondansetron 30 minutes before surgery as preoperative medication. Standard ASA monitoring will be applied, and fasting guidelines will be followed. Depth of anesthesia will be monitored in all patients using BIS, and maintained within a target range of BIS 40-60 to ensure adequate depth with no response to surgical stimuli.

Study Overview

• Status: Not yet recruiting
• Conditions: Obesity; Bariatric Surgery
• Intervention / Treatment: Drug: Intraoperative rescue analgesia; Drug: Intraoperative rescue analgesia:

Detailed Description

This study is designed as a prospective, randomized, controlled clinical trial. It will be conducted in the operating rooms of the University of Health Sciences, Diyarbakır Gazi Yaşargil Training and Research Hospital. Patients aged 18 to 65 years who are scheduled for elective bariatric surgery and meet the inclusion criteria (ASA physical status I-III) will be enrolled in the study.

Eligible patients will be informed both verbally and in writing during their preoperative anesthetic evaluation, and written informed consent will be obtained at least 24 hours prior to surgery.

Patients will be randomly assigned to one of two groups using computer-generated randomization:

Group O (Opioid group)

Group NO (Opioid-free group)

All patients will receive 40 mg IV pantoprazole and 4 mg IV ondansetron 30 minutes before surgery as preoperative medication. Standard ASA monitoring will be applied, and fasting guidelines will be followed. Depth of anesthesia will be monitored in all patients using BIS, and maintained within a target range of BIS 40-60 to ensure adequate depth with no response to surgical stimuli.

Anesthesia Protocol:

Group O (Opioid Group):

General anesthesia will be induced with 2 mg/kg propofol, 2 µg/kg fentanyl, and 0.6 mg/kg rocuronium based on ideal body weight (IBW). Maintenance will be achieved using remifentanil (Ultiva®) infusion at 0.1-0.3 µg/kg/min and 1 MAC sevoflurane. Following induction, all patients will receive a bilateral transversus abdominis plane (TAP) block under ultrasound guidance using 40 mL of 0.25% bupivacaine.

Group NO (Opioid-Free Group):

General anesthesia will be induced with 2 mg/kg propofol, 0.5 mg/kg ketamine, and 0.6 mg/kg rocuronium (IBW). Anesthesia will be maintained with dexmedetomidine infusion at 0.2-1.4 µg/kg/h and 1 MAC sevoflurane. Following induction, a bilateral TAP block will also be performed using 40 mL of 0.25% bupivacaine under ultrasound guidance.

Postoperative Analgesia Protocol:

During skin closure, all patients will receive 1 g IV paracetamol and 50 mg IV ketoprofen. At the end of surgery, neuromuscular blockade will be reversed using sugammadex, and patients will be safely extubated.

In the postoperative period, patients will be followed in the surgical ward for 48 hours with a standardized analgesic protocol:

1 g IV paracetamol every 6 hours

4 mg IV ondansetron every 8 hours

50 mg IV ketoprofen every 12 hours

Pain will be assessed using the Visual Analog Scale (VAS). If VAS ≥ 4, 100 mg IV tramadol will be administered as rescue analgesia, and all interventions will be documented in the patient records.

• Study Type: Interventional
• Enrollment (Estimated): 50
• Phase: Phase 4

Contacts and Locations

• Study Contact: Name: ali K oğuz, specialist Dr in Anestesiology; Phone Number: +905324683045; Email: alikendal.oguz@sbu.edu.tr

Participation Criteria

Eligibility Criteria

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

Description

Inclusion Criteria:

Age 18-65 years

BMI >35

ASA class III-IV

Elective bariatric surgery (e.g., sleeve gastrectomy)

Written informed consent

Exclusion Criteria:

Refusal to participate

Severe cardiac/pulmonary/psychiatric illness

Allergy to study drugs

Conversion to emergency surgery

Withdrawal at any point by patient or investigator

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Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Single

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: Group O (Opioid Group); Induction with: 2 mg/kg IV propofol, 2 μg/kg fentanyl, 0.6 mg/kg rocuronium (ideal body weight) Maintenance:0.1-0.3 μg/kg/min IV remifentanil infusion and 1 MAC sevoflurane Bilateral TAP block: 40 mL of 0.25% bupivacaine under ultrasound guidance	Drug: Intraoperative rescue analgesia; If signs of inadequate analgesia occur (e.g., >20% increase in heart rate or blood pressure), IV remifentanil infusion rate will be titrated upward within the safety margin.
Active Comparator: Group NO (Opioid-Free Group); Induction with: 2 mg/kg IV propofol, 0.5 mg/kg ketamine, 0.6 mg/kg rocuronium Maintenance: 0.2-1.4 μg/kg/h IV dexmedetomidine and 1 MAC sevoflurane Bilateral TAP block: 40 mL of 0.25% bupivacaine under ultrasound guidance	Drug: Intraoperative rescue analgesia: If signs of inadequate analgesia occur (e.g., >20% increase in heart rate or blood pressure), IV dexmedetomidine infusion rate will be titrated upward (up to maximum safe dose).

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Time Frame
Postoperative VAS pain scores	post-op 1.hour (H), 2.H, 3.H, 6.H, 12.H, 18.H, 24.H, 36.H and 48.H
QoR-15 score (Quality of Recovery)	24 Hours and 48 Hours

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Rescue analgesic requirement	IV tramadol	Within 48 hours post-op
Postoperative nausea and vomiting (PONV) incidence questionnaire		48 hours

Collaborators and Investigators

• Sponsor: Siirt Training and Research Hospital

Study record dates

Study Major Dates

• Study Start (Estimated): August 20, 2025
• Primary Completion (Estimated): January 20, 2026
• Study Completion (Estimated): March 1, 2026

Study Registration Dates

• First Submitted: July 30, 2025
• First Submitted That Met QC Criteria: August 5, 2025
• First Posted (Actual): August 6, 2025

Study Record Updates

• Last Update Posted (Actual): August 6, 2025
• Last Update Submitted That Met QC Criteria: August 5, 2025
• Last Verified: July 1, 2025

More Information

Terms related to this study

• Keywords: Pain Management; TAP Block; Multimodal Analgesia; Opioid-Free Anesthesia; Quality of Recovery (QoR-15)
• Other Study ID Numbers: OBES-OFAN-2025-01

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: UNDECIDED
• IPD Plan Description: Data sharing is currently under consideration. A final decision will be made after study completion and ethical approval.

Drug and device information, study documents

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