An interventional study of Opioid-Based Anesthesia (Remifentanil-Based Protocol) and Opioid-Free Anesthesia (Dexmedetomidine-Ketamine-Lidocaine Protocol) in Morbid Obesity, Postoperative Pain and Opioid Free Anesthesia, sponsored by Hospital dos Lusíadas. Completed at 1 site in Portugal. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-02-25.
Sponsored by Hospital dos Lusíadas · Not applicable, Interventional, and Treatment
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.
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.
922 studies on the registry are indexed under Obesity, Morbid; 172 are open to participants now.
This study's enrollment of 60 is close to the median of 60 across 590 interventional studies indexed under Obesity, Morbid.
Browse Obesity, Morbid studies →Hospital dos Lusíadas is the lead sponsor of 2 studies on the registry; none are open to participants now.
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Exclusion Criteria:
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)
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 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.
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.
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: 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).
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.
Time frame: 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.
Time frame: - 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.
Time frame: - 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.
Time frame: At 6 hours and 24 hours after surgery
Need for PONV Treatment
Proportion of patients requiring antiemetic treatment will be evaluated and compared.
Time frame: 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.
Time frame: 48 hours postoperatively (at hospital discharge).
Postoperative Complications
Occurrence of perioperative complications (respiratory, cardiovascular, surgical, or anesthesia-related) will be recorded.
Time frame: Periprocedurally, up to 48 hours postoperatively.
Participants were consecutively recruited at a single tertiary bariatric surgery center (Hospital Lusíadas Amadora, Portugal). Eligible adult patients scheduled for elective laparoscopic bariatric surgery were identified during routine preoperative outpatient consultations. All patients received verbal and written study information, and written informed consent was obtained prior to enrollment. Recruitment continued until the target sample size of 60 participants was achieved.
| Milestone | Opioid-Free Anesthesia (OFA) | Opioid-Based Anesthesia (OBA) |
|---|---|---|
| Started | 30 | 30 |
| Completed | 30 | 30 |
| Not completed | 0 | 0 |
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.
| Score on a scale (0-10) | Opioid-Based Anesthesia (OBA) | Opioid-Free Anesthesia (OFA) |
|---|---|---|
| Within 30 minutes of arrival at the Post-Anesthesia Care Unit (PACU) | 2.5 (0 to 5.5) | 0 (0 to 2) |
| At PACU discharge (assessed up to 2 hours after PACU admission) | 3 (1 to 5) | 1 (0 to 3) |
| Within the first 24 postoperative hours; | 3 (2 to 4) | 1 (0 to 3) |
| 48 hours postoperatively (at hospital discharge) | 0 (0 to 2) | 0 (0 to 0) |
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.
| Participants | Opioid-Based Anesthesia (OBA) | Opioid-Free Anesthesia (OFA) |
|---|---|---|
| NOL index at 15 minutes: <10 | 5 | 11 |
| NOL index at 15 minutes: 10-25 | 7 | 2 |
| NOL index at 30 minutes: <10 | 6 | 12 |
| NOL index at 30 minutes: 10-25 | 4 | 1 |
| NOL index at 30 minutes: 26-45 | 2 | 0 |
| NOL index at 45 minutes: <10 | 10 | 11 |
| NOL index at 45 minutes: 10-25 | 1 | 2 |
| NOL index at 45 minutes: 26-45 | 1 | 0 |
| NOL index at 60 minutes: < 10 | 8 | 13 |
| NOL index at 60 minutes: 10-25 | 2 | 0 |
| NOL index at 60 minutes: 26-45 | 1 | 0 |
| NOL index at 75 minutes: < 10 | 8 | 12 |
| NOL index at 75 minutes: 10-25 | 1 | 1 |
| NOL index at 75 minutes: 26-45 | 1 | 0 |
| NOL index at 90 minutes: < 10 | 5 | 10 |
| NOL index at 90 minutes: 10-25 | 3 | 1 |
| NOL index at 90 minutes: 26-45 | 1 | 0 |
| NOL index at 105 minutes: < 10 | 5 | 7 |
| NOL index at 105 minutes: 10-25 | 1 | 1 |
| NOL index at 105 minutes: 26-45 | 1 | 0 |
| NOL index at 120 minutes: < 10 | 3 | 7 |
| NOL index at 120 minutes: 10-25 | 3 | 1 |
| NOL index at 135 minutes: < 10 | 2 | 6 |
| NOL index at 135 minutes: 10-25 | 1 | 1 |
| NOL index at 150 minutes: < 10 | 1 | 1 |
| NOL index at 150 minutes: 10-25 | 1 | 0 |
| NOL index at 165 minutes: < 10 | 1 | 1 |
| NOL index at 180 minutes: < 10 | 0 | 1 |
| NOL index at 180 minutes: 10-25 | 1 | 0 |
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.
| Participants | Opioid-Based Anesthesia (OBA) | Opioid-Free Anesthesia (OFA) |
|---|---|---|
| Yes - Required rescue analgesia | 22 | 9 |
| No - Did not require rescue analgesia | 8 | 21 |
Need for opioid administration as rescue analgesia will be recorded and compared between groups.
| Participants | Opioid-Based Anesthesia (OBA) | Opioid-Free Anesthesia (OFA) |
|---|---|---|
| Yes - Received opioids | 21 | 8 |
| No - Did not receive opioids | 1 | 1 |
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.
| Participants | Opioid-Based Anesthesia (OBA) | Opioid-Free Anesthesia (OFA) |
|---|---|---|
| PONV Impact Scale score at 6 hours: 0 | 22 | 22 |
| PONV Impact Scale score at 6 hours: 1 | 3 | 4 |
| PONV Impact Scale score at 6 hours: 2 | 4 | 3 |
| PONV Impact Scale score at 6 hours: ≥3 | 1 | 1 |
| PONV Impact Scale score at 24 hours: 0 | 26 | 27 |
| PONV Impact Scale score at 24 hours: 1 | 1 | 1 |
| PONV Impact Scale score at 24 hours: 2 | 1 | 2 |
| PONV Impact Scale score at 24 hours: ≥3 | 2 | 0 |
Proportion of patients requiring antiemetic treatment will be evaluated and compared.
| Participants | Opioid-Based Anesthesia (OBA) | Opioid-Free Anesthesia (OFA) |
|---|---|---|
| Yes - Required PONV treatment | 4 | 5 |
| No - Did not require PONV treatment | 26 | 25 |
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.
| Score on a scale (1-10) | Opioid-Based Anesthesia (OBA) | Opioid-Free Anesthesia (OFA) |
|---|---|---|
| Patient Satisfaction | 9.2 ± 0.9 | 9.5 ± 0.7 |
Occurrence of perioperative complications (respiratory, cardiovascular, surgical, or anesthesia-related) will be recorded.
| Participants | Opioid-Based Anesthesia (OBA) | Opioid-Free Anesthesia (OFA) |
|---|---|---|
| Yes - Experienced postoperative complications | 0 | 0 |
| No - No postoperative complications | 30 | 30 |
Collected over Periprocedurally, up to 48 hours postoperatively.. Non-serious events are listed at a 0% frequency threshold.
| Group | Deaths | Serious | Other |
|---|---|---|---|
| Opioid-Free Anesthesia (OFA) | 0/30 (0%) | 0/30 (0%) | 0/30 (0%) |
| Opioid-Based Anesthesia (OBA) | 0/30 (0%) | 0/30 (0%) | 0/30 (0%) |
All randomized participants were included in the baseline analysis. No participants or units were excluded from baseline analyses.
| Age, Continuous(Years) | Opioid-Free Anesthesia (OFA) | Opioid-Based Anesthesia (OBA) | Total |
|---|---|---|---|
| Mean | 47.2 ± 10.3 | 42.7 ± 10.5 | 44.9 ± 10.6 |
| Sex: Female, Male(Participants) | Opioid-Free Anesthesia (OFA) | Opioid-Based Anesthesia (OBA) | Total |
|---|---|---|---|
| Female | 22 | 24 | 46 |
| Male | 8 | 6 | 14 |
| Race and Ethnicity Not Collected(Participants) | Opioid-Free Anesthesia (OFA) | Opioid-Based Anesthesia (OBA) | Total |
|---|---|---|---|
| Count of participants | — | — | 0 |
| Region of Enrollment(Participants) | Opioid-Free Anesthesia (OFA) | Opioid-Based Anesthesia (OBA) | Total |
|---|---|---|---|
| Portugal | 30 | 30 | 60 |
| Body Mass Index (BMI)(kg/m²) | Opioid-Free Anesthesia (OFA) | Opioid-Based Anesthesia (OBA) | Total |
|---|---|---|---|
| Mean | 39.3 ± 5.0 | 39.0 ± 5.0 | 39.1 ± 5.0 |
| Relevant Comorbidities(Participants) | Opioid-Free Anesthesia (OFA) | Opioid-Based Anesthesia (OBA) | Total |
|---|---|---|---|
| Hypertension | 13 | 9 | 22 |
| Type 2 Diabetes Mellitus | 4 | 3 | 7 |
| OSAS / OHS | 7 | 6 | 13 |
| Depression | 13 | 6 | 19 |
| Dyslipidemia | 12 | 8 | 20 |
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Plan to share: No — Individual participant data will not be shared due to privacy restrictions and institutional regulations. Only aggregated results will be made available in publications.
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