Intraoperative Use of Methadone for Postoperative Pain Control in Bariatric Surgery: A Randomized, Double-Blind, Controlled Clinical Trial

INTRODUCTION: This study aimed to assess postoperative pain in patients who received a single dose of methadone during the anesthetic-surgical procedure, as well as to evaluate adverse effects. Methods: A randomized, double-blind, clinical trial with patients undergoing video laparoscopic bariatric surgery. Immediately after anesthesia induction, the methadone group (MG) received 10 mg of methadone diluted in 100 ml of 0.9% saline, and the Control group (CG) received only 100 ml of 0.9% saline (without methadone in this group). The assessment of pain was made using the visual analog scale (VAS), 10 minutes after extubation in the post-anesthesia care unit (PACU) and six, 12, and 24 hours after surgery. The presence of nausea and vomiting, respiratory depression, and the need for postoperative rescue opioids were analyzed. Results: A total of 16 patients were allocated in the MG and 18 in the CG. The MG showed a lower average of pain scores on the VAS over 24 hours, with a significant difference in the first 10 minutes postoperatively. Furthermore, it showed a greater decrease in VAS pain scores over 24 hours (β = -1.984; p<0.001) compared to the CG. In the postoperative period, no significant difference was found between the groups regarding rescue morphine use within the first 24 hours (p=0,469), except during the PACU period, the rescue morphine use was higher in the CG (p=0,005). There was no significant difference regarding the presence of nausea and vomiting (p=0.372). Conclusion: Our findings suggested that intravenous methadone single dose in laparoscopic bariatric surgery was safe, achieving better postoperative pain outcomes.