Background: Post-lumbar spine surgery is associated with increased morbidity and postoperative complications. Patients who undergo spine surgery often have higher baseline opioid requirements, which lead to an increased perioperative use of opioids, which lead to side effects and complications. N-methyl-D-aspartate (NMDA) receptor antagonists such as ketamine and methadone have been shown to have opioid sparing effects, minimize opioid tolerance, and improve quality of postoperative pain control in chronic pain patients; however, their combined effects remain largely unknown. We hypothesize that post-lumbar spine surgery patients who were administered intraoperative ketamine and methadone have improved postoperative pain scores than those receiving intraoperative ketamine or methadone alone.
Methods: This is a retrospective, single-center study involving patients who were undergoing lumbar spine surgery from February 2013 to January 2017 who received ketamine, methadone or ketamine and methadone combined. Chart review was performed examining their baseline demographics, opioid and adjunct medication use, and pain scores as well as perioperative opioid and adjunct medication use, pain scores and postoperative complications up to 72 hours post surgery.
Results: 58 patients received ketamine only, 67 patients received methadone only, 18 patients received combined ketamine and methadone. Preoperatively, patient’s who received ketamine and methadone combined had a significantly higher baseline opioid requirement with significantly higher baseline pain scores. Postoperatively, the combined ketamine and methadone group received significantly more opioids in the PACU with a trend toward higher requirements at 24, 48 and 72 hours. Patients in the combined group also had significantly higher pain scores in the PACU with a trend towards higher pain scores at 24, 48 and 72 hours. Total length of stay demonstrated a trend towards longer length of stay in the combined group.
Conclusion: Patients who received combined ketamine and methadone in the perioperative period had higher preoperative opioid requirements and pain scores as well as postoperative opioid requirements and pain scores compared to patients who received ketamine or methadone alone. This may be due to a higher likelihood for baseline chronic pain and therefore for providers to administer combined therapy intraoperatively.
