The Effect of Intraoperative Methadone During Spine Fusion Surgery on Postoperative Opioid Requirements

A randomized blinded trial with three groups. To evaluate whether a single intraoperative methadone dose reduces postoperative opioid requirements and pain intensity in patients undergoing lumbar fusion surgery. Spine fusion is associated with significant acute postoperative pain. Methadone's long duration of action may reduce postoperative opioid requirements and pain intensity. Adult patients undergoing lumbar fusion (<5 levels) at University Hospital, (February 2021-March 2024) were randomized to receive 0.2 mg/kg methadone before surgical incision (METpre), 0.2 mg/kg methadone before wound closure (METpost) or 0.2 mg/kg morphine before wound closure (MORpost). The primary outcome was cumulative opioid requirements at 6 and 24 hours (oral morphine equivalents), with secondary outcomes including pain intensity, nausea, sedation, respiratory events, time in the post-anesthetic care unit and patient satisfaction. The follow-up period included 72 hours in-hospital and 3 months at home following surgery. Of 124 patients enrolled, 113 completed the trial (38 METpre, 39 METpost, 36 MORpost) with a mean [SD] age of 64.2 [11.5] years; 45 (39.8%) were male. Postoperative opioid requirements were similar in all three groups at 6 hours (median, [IQR], METpre: 85 mg [27.5 to 112.5] vs. METpost: 77.8 mg [45 to 120] vs. MORpost: 92.5 [48.8-146.3] P=0.518) and at 24 hours (median, [IQR], METpre: 141.5 mg [87.5 to 245.5] vs. METpost 153.25 mg [102.5 to 239] vs. MORpost: 183.8 [113.8 - 268.8] P=0.457). Pain intensities were similar between the three groups, with exception of lower pain intensity at 48 and 72 hours in METpre. Adverse events were rare and not different between groups. Three months follow-up showed no between-group differences in opioid requirements or pain intensity. A single intraoperative methadone dose did not reduce opioid requirements after lumbar fusion surgery compared to morphine.