Opioid-Free vs Opioid-Based Anesthesia in Bariatric Surgery

Opioid-free Anesthesia vs Opioid-based Anesthesia / A Heavyweight Showdown - Randomized Controlled Trial

This prospective randomized controlled trial aims to compare the clinical effectiveness and safety of opioid-free anesthesia (OFA) versus traditional opioid-based anesthesia (OBA) in adult patients undergoing laparoscopic bariatric surgery. The study evaluates postoperative pain, need for rescue analgesia, incidence of postoperative nausea and vomiting (PONV), intraoperative nociception monitoring (NOL index), and patient satisfaction. A total of 60 patients were randomized into two parallel groups receiving either OFA or OBA according to standardized anesthetic protocols.

Study Overview

• Status: Completed
• Conditions: Postoperative Pain; Morbid Obesity; Bariatric Surgery; Opioid Free Anesthesia
• Intervention / Treatment: Drug: Opioid-Based Anesthesia (Remifentanil-Based Protocol); Drug: Opioid-Free Anesthesia (Dexmedetomidine-Ketamine-Lidocaine Protocol)

Detailed Description

Bariatric surgery is the most effective treatment for severe and morbid obesity, but perioperative pain management and PONV remain significant challenges. Traditional opioid-based anesthesia is associated with adverse effects such as respiratory depression, postoperative hyperalgesia, ileus, and delayed recovery.

Opioid-free anesthesia is an emerging strategy based on the use of multimodal, non-opioid agents-including dexmedetomidine, lidocaine, and ketamine-aimed at providing adequate analgesia while reducing opioid-related complications.

This randomized controlled trial evaluates whether OFA improves postoperative pain control, reduces the requirement for rescue analgesia, and promotes better perioperative outcomes compared to OBA in laparoscopic bariatric surgery. Outcomes include NRS pain scores at multiple time points, NOL monitoring during surgery, PONV occurrence, and patient satisfaction at discharge.

• Study Type: Interventional
• Enrollment (Actual): 60
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Portugal
  • Amadora, Portugal, 2724-002
    • Hospital Lusíadas Amadora - Lusíadas Saúde, S.A.

Participation Criteria

Eligibility Criteria

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

Description

Inclusion Criteria:

• Age ≥ 18 years;
• Body mass index (BMI ≥ 35 kg/m² with associated comorbidities) or BMI ≥ 40 kg/m²;
• Scheduled for elective laparoscopic bariatric surgery;
• Ability to provide informed consent.

Exclusion Criteria:

• Pregnancy;
• History of substance abuse;
• Severe psychiatric disease;
• Contraindications to any of the drugs used in either anesthetic protocol (dexmedetomidine, ketamine, lidocaine, remifentanil, etc.);
• Inability to comply with study procedures;
• Refusal or inability to provide informed consent.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: Opioid-Based Anesthesia (OBA); Standard opioid-based anesthesia using remifentanil infusion plus propofol induction, desflurane maintenance, and conventional multimodal analgesia, with opioids permitted for rescue.	Drug: Opioid-Based Anesthesia (Remifentanil-Based Protocol); Participants receive standard opioid-based general anesthesia consisting of: Continuous remifentanil infusion (2 mg diluted in 40 mL saline),; Propofol for induction,; Rocuronium for neuromuscular blockade,; Desflurane for maintenance,; Dexamethasone 4-8 mg for PONV prophylaxis,; Cefazolin for antibiotic prophylaxis,; Esomeprazole for stress-ulcer prevention. Postoperative analgesia includes paracetamol + ketorolac/parecoxib + metamizole, with tramadol and/or morphine provided as rescue. NOL, BIS, TOF, and standard monitoring are used.
Experimental: Opioid-Free Anesthesia (OFA); Opioid-free anesthesia using dexmedetomidine, ketamine, and lidocaine infusion, combined with propofol induction, desflurane maintenance, and opioid-free multimodal analgesia, continued into early recovery.	Drug: Opioid-Free Anesthesia (Dexmedetomidine-Ketamine-Lidocaine Protocol); Participants receive opioid-free anesthesia consisting of: Dexmedetomidine bolus (15-20 μg),; Continuous infusion of dexmedetomidine 50 μg + ketamine 50 mg + lidocaine 500 mg in 50 mL saline (rate: 1 mL/10 kg),; Propofol for induction,; Rocuronium for neuromuscular blockade,; Desflurane for maintenance,; Dexamethasone for PONV prophylaxis,; Cefazolin and esomeprazole for prophylaxis.; The analgesic infusion is reduced by half 30 min before end of surgery and continued for 1 hour in PACU. Postoperative analgesia includes paracetamol + ketorolac/parecoxib + metamizole, with tramadol 100 mg as rescue. Monitoring includes NOL, BIS, TOF.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Postoperative Pain Intensity Measured by the Numerical Rating Scale for Pain (NRS)	Postoperative pain will be assessed using the Numerical Rating Scale for Pain (NRS), a validated 11-point scale ranging from 0 (no pain) to 10 (worst pain imaginable). Higher scores indicate a worse outcome, reflecting greater pain intensity. Pain intensity will be compared between the opioid-free anesthesia group and the opioid-based anesthesia group at predefined postoperative time points.	Time Frame: - Within 30 minutes of arrival at the Post-Anesthesia Care Unit (PACU); - At PACU discharge (assessed up to 2 hours after PACU admission); - Within the first 24 postoperative hours; - 48 hours postoperatively (at hospital discharge).

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Intraoperative Nociception (NOL Index)	Nociception will be assessed using the NOL (Nociception Level) Index, a multiparametric autonomic signal-based monitor. Lower values reflect better nociceptive control. Comparisons will be made between OFA and OBA groups at all recorded time points.	Multiple standardized time points during surgery (15 to 180 minutes)
Need for Rescue Analgesia	The proportion of patients requiring rescue analgesia (tramadol and/or morphine) will be compared between the opioid-free anesthesia group and the opioid-based anesthesia group.	- During PACU stay (assessed up to 2 hours after PACU admission).
Opioid Consumption	Need for opioid administration as rescue analgesia will be recorded and compared between groups.	- During PACU stay (assessed up to 2 hours after PACU admission).
Incidence of Postoperative Nausea and Vomiting (PONV)	PONV will be assessed using the Postoperative Nausea and Vomiting Impact Scale, comparing frequency and severity between groups. The total score ranges from 0 (no nausea or vomiting) to 6 (maximum impact). Higher scores indicate a worse outcome, reflecting greater severity and clinical impact of postoperative nausea and vomiting.	At 6 hours and 24 hours after surgery
Need for PONV Treatment	Proportion of patients requiring antiemetic treatment will be evaluated and compared.	First 24 postoperative hours
Patient Satisfaction	Patient satisfaction will be assessed using a Numerical Satisfaction Rating Scale and compared between groups. Total score ranges from 1 (minimum satisfaction) to 10 (maximum satisfaction). Higher scores indicate a better outcome, reflecting greater patient satisfaction.	48 hours postoperatively (at hospital discharge).
Postoperative Complications	Occurrence of perioperative complications (respiratory, cardiovascular, surgical, or anesthesia-related) will be recorded.	Periprocedurally, up to 48 hours postoperatively.

Collaborators and Investigators

• Sponsor: Hospital dos Lusíadas
• Investigators: Principal Investigator: Emanuel J Almeida, MD, Hospital dos Lusíadas

Study record dates

Study Major Dates

• Study Start (Actual): October 2, 2023
• Primary Completion (Actual): April 19, 2024
• Study Completion (Actual): April 21, 2024

Study Registration Dates

• First Submitted: December 10, 2025
• First Submitted That Met QC Criteria: January 6, 2026
• First Posted (Actual): January 13, 2026

Study Record Updates

• Last Update Posted (Actual): February 25, 2026
• Last Update Submitted That Met QC Criteria: February 22, 2026
• Last Verified: February 1, 2026

More Information

Terms related to this study

• Keywords: Bariatric surgery; Postoperative pain; Morbid obesity; Nausea and Vomiting; Opioid-free anesthesia
• Additional Relevant MeSH Terms: Pain; Neurologic Manifestations; Postoperative Complications; Pathologic Processes; Nutrition Disorders; Overnutrition; Body Weight; Signs and Symptoms, Digestive; Overweight; Obesity; Pathological Conditions, Signs and Symptoms; Nutritional and Metabolic Diseases; Signs and Symptoms; Pain, Postoperative; Nausea; Vomiting; Obesity, Morbid
• Other Study ID Numbers: CESHLAM17072023

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: Individual participant data will not be shared due to privacy restrictions and institutional regulations. Only aggregated results will be made available in publications.

Drug and device information, study documents

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