Not provided
Not provided
Not provided
Not provided
Not provided
Not provided
Not provided
Not provided
Not provided
Not provided
Not provided
Not provided
Not provided
Not provided
Not provided
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.
Not provided
Not provided
Not provided
Not provided
| Label | Type | Description | Intervention Names |
|---|---|---|---|
| Opioid-Based Anesthesia (OBA) | Active Comparator | Standard opioid-based anesthesia using remifentanil infusion plus propofol induction, desflurane maintenance, and conventional multimodal analgesia, with opioids permitted for rescue. |
|
| Opioid-Free Anesthesia (OFA) | Experimental | Opioid-free anesthesia using dexmedetomidine, ketamine, and lidocaine infusion, combined with propofol induction, desflurane maintenance, and opioid-free multimodal analgesia, continued into early recovery. |
|
| Name | Type | Description | Arm Group Labels | Other Names |
|---|---|---|---|---|
| Opioid-Based Anesthesia (Remifentanil-Based Protocol) | Drug | Participants receive standard opioid-based general anesthesia consisting of:
Postoperative analgesia includes paracetamol + ketorolac/parecoxib + metamizole, with tramadol and/or morphine provided as rescue. NOL, BIS, TOF, and standard monitoring are used. |
| 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). |
| 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) |
Not provided
Inclusion Criteria:
Exclusion Criteria:
Not provided
Not provided
Not provided
Not provided
Not provided
Not provided
| Name | Affiliation | Role |
|---|---|---|
| Emanuel J Almeida, MD | Hospital dos Lusíadas | Principal Investigator |
| Facility | Status | City | State | ZIP | Country | Contacts |
|---|---|---|---|---|---|---|
| Hospital Lusíadas Amadora - Lusíadas Saúde, S.A. | Amadora | 2724-002 | Portugal |
| PubMed Identifier | Type | Citation | Retractions |
|---|---|---|---|
| 42185786 | Derived | Almeida E, Almeida F, Rossoni C, Ribeiro R. Opioid-free versus opioid-based anesthesia in laparoscopic bariatric surgery: an exploratory randomized pilot trial. BMC Anesthesiol. 2026 May 25. doi: 10.1186/s12871-026-03838-4. Online ahead of print. |
Not provided
Not provided
Individual participant data will not be shared due to privacy restrictions and institutional regulations. Only aggregated results will be made available in publications.
Not provided
Not provided
Not provided
Not provided
After enrollment and informed consent, no significant events, exclusions, or withdrawals occurred prior to randomization. All participants were assigned to their respective study groups.
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.
Not provided
| ID | Title | Description |
|---|---|---|
| FG000 | 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. |
| FG001 | 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. |
| Title | Milestones | Reasons Not Completed | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Overall Study |
|
All randomized participants were included in the baseline analysis. No participants or units were excluded from baseline analyses.
Not provided
| ID | Title | Description |
|---|---|---|
| BG000 | 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. |
| BG001 | Opioid-Based Anesthesia (OBA) |
| Units | Counts |
|---|---|
| Participants |
|
| Title | Description | Population Description | Parameter Type | Dispersion Type | Unit of Measure | Calculate Percentage | Denominator Units Selected | Denominators | Classes |
|---|---|---|---|---|---|---|---|---|---|
| Age, Continuous | Age was recorded in years at the time of surgery, based on the participant's date of birth documented in the medical record. |
| Type | Title | Description | Population Description | Reporting Status | Anticipated Posting Date | Parameter Type | Dispersion Type | Unit of Measure | Calculate Percentage | Time Frame | Units Analyzed | Denominator Units Selected | Arm/Group Information | Denominators | Classes | Analyses | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Primary | 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. | All randomized participants were included in the analysis of postoperative pain intensity. Pain assessments were available for all participants at the predefined time points, and no participants were excluded from this outcome analysis. | Posted | Median | Inter-Quartile Range | Score on a scale (0-10) | 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). |
|
Periprocedurally, up to 48 hours postoperatively.
Participants were monitored for adverse events from surgery until hospital discharge. Serious and non-serious adverse events were actively assessed and recorded according to standard institutional perioperative monitoring protocols. No adverse events were reported.
Not provided
| ID | Title | Description | Deaths (Affected) | Deaths (At Risk) | Serious Events (Affected) | Serious Events (At Risk) | Other Events (Affected) | Other Events (At Risk) |
|---|---|---|---|---|---|---|---|---|
| EG000 | 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. |
Not provided
Not provided
This study was conducted at a single center with a relatively small sample size, which may limit the generalizability of the findings. The trial was retrospectively registered, and some intraoperative measurements (NOL index) were available only for a subset of participants, with the number of observations varying across time points due to differences in surgical duration. Differences in antiemetic prophylaxis between groups may also have influenced postoperative nausea and vomiting outcomes.
| Title | Organization | Phone | Extension | |
|---|---|---|---|---|
| Emanuel Almeida | Hospital Lusíadas Amadora, Portugal | +351963502309 | emanueljoao7@gmail.com |
Not provided
| Type | Includes Protocol | Includes SAP | Includes ICF | Document Label | Document Date | Document Uploaded Date | Document File Name |
|---|---|---|---|---|---|---|---|
| Prot | Yes | No | No | Study Protocol | Feb 4, 2026 | Feb 22, 2026 | Prot_002.pdf |
| SAP | No | Yes | No | Statistical Analysis Plan | Jul 1, 2023 | Jan 15, 2026 | SAP_003.pdf |
| ICF | No | No | Yes | Informed Consent Form | Jul 1, 2023 | Dec 10, 2025 | ICF_001.pdf |
Not provided
| ID | Term |
|---|---|
| D009767 | Obesity, Morbid |
| D010149 | Pain, Postoperative |
| D009325 | Nausea |
| D014839 | Vomiting |
| ID | Term |
|---|---|
| D009765 | Obesity |
| D050177 | Overweight |
| D044343 | Overnutrition |
| D009748 | Nutrition Disorders |
Not provided
Not provided
Prospective, randomized, two-arm parallel-group clinical trial comparing opioid-free anesthesia versus opioid-based anesthesia in patients undergoing laparoscopic bariatric surgery.
Not provided
Not provided
No blinding was implemented. Both participants and care providers were aware of group allocation.
Not provided
|
| Opioid-Free Anesthesia (Dexmedetomidine-Ketamine-Lidocaine Protocol) | Drug | Participants receive opioid-free anesthesia consisting of:
Postoperative analgesia includes paracetamol + ketorolac/parecoxib + metamizole, with tramadol 100 mg as rescue. Monitoring includes NOL, BIS, TOF. |
|
| 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. |
Standard opioid-based anesthesia using remifentanil infusion plus propofol induction, desflurane maintenance, and conventional multimodal analgesia, with opioids permitted for rescue. |
| BG002 | Total | Total of all reporting groups |
Age data were available for all randomized participants, and no participants were excluded from this baseline measure. |
| Mean |
| Standard Deviation |
| Years |
|
| Sex: Female, Male | Biological sex was recorded as male or female, as documented in the participant's medical record at the time of enrollment. | Sex data were available for all randomized participants, and no participants were excluded from this baseline measure. | Count of Participants | Participants |
|
| Race and Ethnicity Not Collected | Race and Ethnicity were not collected from any participant. | Count of Participants | Participants |
|
| Region of Enrollment | Participants were enrolled at a single clinical site located in Europe, specifically in Portugal. | Region of enrollment information was available for all randomized participants, with no differences between the numbers reported for this measure and the overall study population. | Number | Participants |
|
| Body Mass Index (BMI) | Body mass index was calculated as weight in kilograms divided by height in meters squared (kg/m²), measured during the preoperative assessment prior to surgery. | Mean | Standard Deviation | kg/m² |
|
| Relevant Comorbidities | Relevant comorbidities included hypertension, type 2 diabetes mellitus, obstructive sleep apnea syndrome or obesity hypoventilation syndrome (OSAS/OHS), depression and dyslipidemia, as documented in the preoperative medical records based on established clinical diagnoses. | Count of Participants | Participants |
|
| 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. |
| OG001 | 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. |
|
|
| Secondary | 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. | Intraoperative NOL measurements were available only for a subset of participants. The number of participants contributing data at each time point varied due to differences in surgical duration, as later time points were reached only by longer procedures. | Posted | Count of Participants | Participants | Multiple standardized time points during surgery (15 to 180 minutes) |
|
|
|
| Secondary | 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. | All randomized participants were included in the analysis of rescue analgesia requirements. Data on the need for rescue analgesia were available for all participants, and no participants were excluded from this outcome analysis. | Posted | Count of Participants | Participants | - During PACU stay (assessed up to 2 hours after PACU admission). |
|
|
|
| Secondary | Opioid Consumption | Need for opioid administration as rescue analgesia will be recorded and compared between groups. | The analysis of opioid use included only participants who required rescue analgesia during the PACU stay (assessed up to 2 hours after PACU admission). Among these participants, opioid administration was recorded. Participants who did not require rescue analgesia were not included in this analysis. | Posted | Count of Participants | Participants | - During PACU stay (assessed up to 2 hours after PACU admission). |
|
|
|
| Secondary | 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. | All randomized participants were included in the analysis of postoperative nausea and vomiting. PONV data were available for all participants at the predefined postoperative time points, and no participants were excluded from this outcome analysis. | Posted | Count of Participants | Participants | At 6 hours and 24 hours after surgery |
|
|
|
| Secondary | Need for PONV Treatment | Proportion of patients requiring antiemetic treatment will be evaluated and compared. | All randomized participants were included in the analysis of the need for treatment of postoperative nausea and vomiting. Data were available for all participants, and no participants were excluded from this outcome analysis. | Posted | Count of Participants | Participants | First 24 postoperative hours |
|
|
|
| Secondary | 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. | All randomized participants were included in the analysis of patient satisfaction. Satisfaction scores were available for all participants at hospital discharge, and no participants were excluded from this outcome analysis. | Posted | Mean | Standard Deviation | Score on a scale (1-10) | 48 hours postoperatively (at hospital discharge). |
|
|
|
| Secondary | Postoperative Complications | Occurrence of perioperative complications (respiratory, cardiovascular, surgical, or anesthesia-related) will be recorded. | All randomized participants were included in the analysis of postoperative complications. Data were available for all participants during the hospital stay, and no participants were excluded from this outcome analysis. | Posted | Count of Participants | Participants | Periprocedurally, up to 48 hours postoperatively. |
|
|
|
| 0 |
| 30 |
| 0 |
| 30 |
| 0 |
| 30 |
| EG001 | 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. | 0 | 30 | 0 | 30 | 0 | 30 |
Not provided
Not provided
Not provided
| D009750 |
| Nutritional and Metabolic Diseases |
| D001835 | Body Weight |
| D012816 | Signs and Symptoms |
| D013568 | Pathological Conditions, Signs and Symptoms |
| D011183 | Postoperative Complications |
| D010335 | Pathologic Processes |
| D010146 | Pain |
| D009461 | Neurologic Manifestations |
| D012817 | Signs and Symptoms, Digestive |
| NOL index at 15 minutes: 10-25 |
|
|
| NOL index at 30 minutes: <10 |
|
|
| NOL index at 30 minutes: 10-25 |
|
|
| NOL index at 30 minutes: 26-45 |
|
|
| NOL index at 45 minutes: <10 |
|
|
| NOL index at 45 minutes: 10-25 |
|
|
| NOL index at 45 minutes: 26-45 |
|
|
| NOL index at 60 minutes: < 10 |
|
|
| NOL index at 60 minutes: 10-25 |
|
|
| NOL index at 60 minutes: 26-45 |
|
|
| NOL index at 75 minutes: < 10 |
|
|
| NOL index at 75 minutes: 10-25 |
|
|
| NOL index at 75 minutes: 26-45 |
|
|
| NOL index at 90 minutes: < 10 |
|
|
| NOL index at 90 minutes: 10-25 |
|
|
| NOL index at 90 minutes: 26-45 |
|
|
| NOL index at 105 minutes: < 10 |
|
|
| NOL index at 105 minutes: 10-25 |
|
|
| NOL index at 105 minutes: 26-45 |
|
|
| NOL index at 120 minutes: < 10 |
|
|
| NOL index at 120 minutes: 10-25 |
|
|
| NOL index at 135 minutes: < 10 |
|
|
| NOL index at 135 minutes: 10-25 |
|
|
| NOL index at 150 minutes: < 10 |
|
|
| NOL index at 150 minutes: 10-25 |
|
|
| NOL index at 165 minutes: < 10 |
|
|
| NOL index at 180 minutes: < 10 |
|
|
| NOL index at 180 minutes: 10-25 |
|
|
| PONV Impact Scale score at 6 hours: 2 |
|
| PONV Impact Scale score at 6 hours: ≥3 |
|
| PONV Impact Scale score at 24 hours: 0 |
|
| PONV Impact Scale score at 24 hours: 1 |
|
| PONV Impact Scale score at 24 hours: 2 |
|
| PONV Impact Scale score at 24 hours: ≥3 |
|