The association between intraoperative ketamine administration and reduced postoperative opioid consumption among chronic opioid users after multilevel lumbar fusion.

Abstract

Achieving postoperative pain control while minimizing opioid dependence is a challenge in surgery. Intraoperative ketamine administration in patients undergoing surgery has been associated with decreased postoperative opioid consumption. This study aimed to determine postoperative opioid consumption after multilevel lumbar spine fusion in patients who received intraoperative ketamine compared to those who did not. A retrospective observational study was performed for 434 participants who underwent a ≥ 2-level lumbar spine fusion surgery. Propensity score weighting was used to evaluate the association between ketamine administration and net outpatient opioid consumption at 1, 3, 6, and 12 months postoperatively. Patients were stratified into subgroups based on chronicity and magnitude of preoperative opioid exposure. The association between intraoperative ketamine and postoperative opioid consumption was examined in all subgroups. Compared to the control group, patients who received intraoperative ketamine presented with a significantly higher number of readmissions (mean 0.291 [SD 0.75] vs 0.475 [SD 0.874], p = 0.045) and higher mean opioid usage in the year prior to surgery (5089 [SD 16,813] vs 11,801 [SD 28,043] morphine milligram equivalents [MMEs]; p = 0.016). Among patients with long-term preoperative opioid use, those who received ketamine consumed 41% fewer total MMEs (1470 MMEs) than the control group (2308 MMEs; p = 0.011) at 1 month postoperatively. There was no significant change in opioid use at 1, 3, 6, or 12 months postoperatively in the two groups. There was no difference in the incidence of long-term postoperative opioid use, visual analog scale (VAS) score at discharge, VAS pain scores, and length of stay. In patients with chronic opioid use, intraoperative ketamine administration was associated with decreased opioid use at 1 month postoperatively following multilevel lumbar spine fusion. Ketamine should be considered an important adjuvant treatment for intraoperative pain management in patients with long-term opioid use. However, ketamine should be used with caution in opioid-naive patients as there was an increased incidence of long-term postoperative opioid use in this group.