Perioperative methadone prescribing and association with respiratory depression

Objective: Over 80 percent of surgery patients experience acute post-operative pain and less than half feel their pain is adequately controlled. Patients receiving chronic opioids, including methadone, are at the highest risk of inadequate pain control. Guidelines do not provide specific recommendations for analgesia management in this population. The purpose of this study was to evaluate the association between post-operative methadone use and respiratory depression.Design: This study was a single center, retrospective, cohort study of adult patients.Setting: Patients included were admitted to a single academic medical center from July 2016 to September 2018.Participants: Medical records of adult inpatients with an operative procedure who received perioperative methadone were reviewed.Main outcome measures: Preoperative methadone use was evaluated for all patients. Post-operative methadone dosing was compared to preoperative methadone dosing. Post-operative respiratory depression was evaluated. Logistic regression was performed to identify risk factors for respiratory depression.Results: Two hundred ninety-eight patients were included in the study. Patients were divided into groups based on preoperative methadone use. Over 90 percent of patients were on preoperative methadone. There were no significant differences in baseline characteristics between groups. In the initial seven post-operative days, 14.8 percent of patients had documented respiratory depression. Respiratory depression was more common among patients who were newly initiated on methadone post-operatively. Factors associated with respiratory depression included male sex, increased age, and new post-operative methadone initiation.Conclusions: Most patients who were administered post-operative methadone were on preoperative methadone. New post-operative methadone initiation was a risk factor for respiratory depression.