Safety profile of intraoperative methadone for analgesia after major spine surgery: An observational study of 1,478 patients.

Objective: To investigate the incidence of perioperative adverse events in patients receiving intravenous methadone for major spine surgery.
Design: Retrospective review of perioperative records from March 2011 and February 2016.
Setting: University of Virginia Healthsystem.
Patients: Adult patients undergoing elective spinal fusion of two or more levels.
Main Outcome Measures: Incidence of respiratory depression, time to extubation, hypotension, hypoxemia, reintubation, cardiac complications, and death.
Results: Reviewed 1,478 patient records. Mean intraoperative methadone dose was 0.14 ± 0.07 mg/kg. A total of 1,142 patients (77.4 percent) were extubated in the operating room, 543 (36.8 percent) experienced respiratory depression, 1,180 (79.8 percent) hypoxemia, and 22 (1.5 percent) required reintubation. Cardiac complications included arrhythmias (289 patients, 29.9 percent), QTc prolongation (568 patients, 58.8 percent), and myocardial infarction (16 patients, 1.1 percent). Two in hospital deaths occurred (0.14 percent).
Conclusions: Mild-moderate respiratory depression is observed following a one-time dose of intraoperative methadone, and monitoring in an appropriate postoperative setting is recommended.