Opioid-free anesthesia compared to standard anesthesia for bariatric surgery: clinical trial

INTERVENTION: All patients will be randomly distributed, using specific software, into 2 groups: experimental (group E) represented by opioid‐free anesthesia and control (group C) represented by opioid‐based anesthesia. The selection of groups will be determined by random randomization in opaque, sealed and sequentially numbered envelopes, with the opening of the envelope performed after admission of the patient to the operating room. Patient data will be recorded in separate tables, one for entry into the operating room and another for data collection with subsequent cross‐referencing of information and data analysis. The researcher will not be aware of the group to which the patient belongs, so that there is no interference in the collection and interpretation of data. Syringes containing dexmetedomidine (group E) or remifentanil (group C) will be prepared by another anesthesiologist not participating in the study. Anesthetic induction and maintenance medications and other drugs will follow a fixed protocol described below, without distinction. For anesthetic induction, in addition to propofol (3 mg/kg of PI), a 50 ml syringe will be prepared to be attached to a continuous infusion pump. In group C, the syringe will contain 2 mg of remifentanil in 50 ml of 0.9% saline (40 mcg/ml). In group E, the syringe will have 100mcg of dexmetedomidine in 50 ml of 0.9% saline (2 mcg/ml). So that the anesthesiologist does not know which medication will be administered, the flow calculation will be done as follows: 0.3 ml/kg/hr to 0.5 ml/kg/hr of Lean Body Weight (LBW). Thus, the doses of remifentanil will be from 0.2 to 0.33 mcg/kg/min of LBW, while the dose of dexmetedomidine will be between 0.6 to 1 mcg/kg/hr of LBW. In both groups, this continuous infusion should be completed concomitantly D02.241.081.751.756 CONDITION: C18.654.726.500 Morbid Obesity PRIMARY OUTCOME: The primary outcome measure is the assessment of the incidence of composite opioid‐related adverse effects in the first hours after extubation and during hospitalization. The components of the composition will be nausea and vomiting, hypoxemia, defined as Sp02 below 90% with need for supplemental oxygen, and sedation, defined as a score greater or equal to 2 on the Wilson scale. SECONDARY OUTCOME: Arterial Hypotension (Mean arterial pressure less than 60 mmHg) Bradycardia incidence (Heart rate less than 40 bpm) Hypoxemia incidence (SatO2 less than 90%) Pain burden Pain intensity through verbal numeric rating scale (NRS) Patient satisfaction through numeric verbal scale Postanestia care unit lenght of stay Postoperative nausea and vomiting incidence (PONV) Quality of Recovery using QoR‐15 questionnaire Rescue opioid consumption INCLUSION CRITERIA: Patients included in the study protocol must meet the following prerequisites: age between 18 and 65 years; with a Body Mass Inde X(BMI) higher than 40 kg/m2 regardless of the presence of comorbidities or a BMI between 35 and 39.9 kg/ m2 in the presence of comorbidities; classified in the physical status ASA (American Society of Anaesthesiologists) of II or III; patients undergoing laparoscopic gastroplasty surgery under general anesthesia; expected hospital stay of up to 36 hours.