Use of Methadone to control postoperative pain in Gastric Bypass Surgery

INTERVENTION: D02.522.675 This is a double‐blind randomized clinical trial, with patients who will undergo bariatric surgery at the University Hospital Onofre Lopes in the year two thousand and twenty‐two, a simple randomization will be performed through closed and sequentially numbered envelopes with a total of forty‐si Xpatients, twenty‐three in a methadone group and twenty‐three in a placebo group, the envelopes will be opened by the anesthesiologist who will conduct the case, the patients will be randomized into two groups, the methadone group that will receive intravenous methadone after anesthetic induction, at a dose of 0.1 mg per kilogram of weight (maximum dose twenty mg), diluted in a 100 ml bottle of saline solution and the control group that will receive a 100 ml bottle of saline solution without medication, intravenously, after anesthetic induction, the 100 ml vials of pure saline solution or with the dose of methadone will be prepared by one of the researchers outside the operating room and will be delivered, without ID. inform the anesthetist who will conduct the case, the weight used to calculate the doses will be the ideal weight added to twenty percent of the weight, as specified by the Robinson formula, balanced general anesthesia will be performed, without neuraxial block or wall blocks abdominal, anesthesia will be at the discretion of the anesthesiologist scheduled for surgery, following the following standardization regarding opioids in both groups: anesthetic induction with fentanyl or sufentanil, anesthetic maintenance not using remifentanil and pain control after extubation with titrated morphine every two mg intravenously every five minutes, patients will receive intraoperative non‐steroidal anti‐inflammatory drugs and dipyrone if they are not allergic, they cannot rec CONDITION: C23.888.592.612 Postoperative Pain; Bariatric Surgery PRIMARY OUTCOME: To assess postoperative pain in patients who received a single dose of methadone during the anesthetic‐surgical procedure SECONDARY OUTCOME: Compare side effects such as nausea and vomiting, need for supplemental O2 and respiratory depression between those who received methadone and those who did not Evaluate reduction in the consumption of rescue analgesics INCLUSION CRITERIA: Patients undergoing primary (non‐revision) bariatric surgeries by videolparoscopy; Physical status American Society of Anesthesiology (ASA) II/III; Age between 18 and 65 years