Bariatric Surgery, Morbid Obesity, Opioid Free Anesthesia, Postoperative Pain
Conditions
Keywords
Opioid-free anesthesia, Bariatric surgery, Morbid obesity, Nausea and Vomiting, Postoperative pain
Brief summary
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.
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.
Interventions
DRUGOpioid-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.
DRUGOpioid-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.
Sponsors
Hospital dos Lusíadas
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT
Masking
NONE
Masking description
No blinding was implemented. Both participants and care providers were aware of group allocation.
Intervention model description
Prospective, randomized, two-arm parallel-group clinical trial comparing opioid-free anesthesia versus opioid-based anesthesia in patients undergoing laparoscopic bariatric surgery.
Eligibility
Sex/Gender
ALL
Age
18 Years to No maximum
Healthy volunteers
No
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.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Postoperative Pain Intensity Measured by the Numerical Rating Scale for Pain (NRS) | 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). | 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. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Intraoperative Nociception (NOL Index) | Multiple standardized time points during surgery (15 to 180 minutes) | 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. |
| Need for Rescue Analgesia | - During PACU stay (assessed up to 2 hours after PACU admission). | 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. |
| Opioid Consumption | - During PACU stay (assessed up to 2 hours after PACU admission). | Need for opioid administration as rescue analgesia will be recorded and compared between groups. |
| Incidence of Postoperative Nausea and Vomiting (PONV) | At 6 hours and 24 hours after surgery | 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. |
| Need for PONV Treatment | First 24 postoperative hours | Proportion of patients requiring antiemetic treatment will be evaluated and compared. |
| Patient Satisfaction | 48 hours postoperatively (at hospital discharge). | 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. |
| Postoperative Complications | Periprocedurally, up to 48 hours postoperatively. | Occurrence of perioperative complications (respiratory, cardiovascular, surgical, or anesthesia-related) will be recorded. |
Countries
Portugal
Contacts
PRINCIPAL_INVESTIGATOREmanuel J Almeida, MD
Hospital dos Lusíadas
Participant flow
Recruitment details
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.
Pre-assignment details
After enrollment and informed consent, no significant events, exclusions, or withdrawals occurred prior to randomization. All participants were assigned to their respective study groups.
Baseline characteristics
| Characteristic | — |
|---|---|
| Age, Continuous | 44.9 Years STANDARD_DEVIATION 10.6 |
| Body Mass Index (BMI) | 39.0 kg/m² STANDARD_DEVIATION 5 |
| Race and Ethnicity Not Collected | 0 Participants |
| Region of Enrollment Portugal | 60 Participants |
| Relevant Comorbidities Depression | 6 Participants |
| Relevant Comorbidities Dyslipidemia | 20 Participants |
| Relevant Comorbidities Hypertension | 22 Participants |
| Relevant Comorbidities OSAS / OHS | 6 Participants |
| Relevant Comorbidities Type 2 Diabetes Mellitus | 7 Participants |
| Sex: Female, Male Female | 24 Participants |
| Sex: Female, Male Male | 14 Participants |
Adverse events
| Event type | EG000 affected / at risk | EG001 affected / at risk |
|---|---|---|
| deaths Total, all-cause mortality | 0 / 30 | 0 / 30 |
| other Total, other adverse events | 0 / 30 | 0 / 30 |
| serious Total, serious adverse events | 0 / 30 | 0 / 30 |
Outcome results
None listed