Perioperative Ketamine in Opioid-Tolerant Patients Undergoing Lumbar Spine Surgery

The goal of this study is to determine whether comprehensive perioperative administration of the N-methyl-D-aspartate (NMDA) receptor antagonist ketamine can increase postoperative pain tolerance and reduce opiate consumption in chronic back pain patients undergoing spinal laminectomy/fusion when compared to placebo Opioid dependence will be defined as daily opioid use (2 or more doses per day) for a period of two-months or longer. Intraoperatively, patients will receive a 1 mg/kg dose of intravenous ketamine or saline with 15 minutes after induction of general anesthesia. Thereafter, a continuous infusion of 0.20 mg/kg/hr ketamine with a maximum dose of 20 mg/hr or saline will be run to conclude at 24 hours after the end of the surgery (fascial closure). The primary outcome measure will be hydromorphone PCA usage during the first 72 hours postoperatively. Secondary outcome measures will be VAS pain scores at rest and with movement in PACU, 24 hr, 48 hr, 72 hr, 2 week (post-op visit), 6 week follow-up visit, as well as, McGill Pain Questionnaire, Pain Catastrophizing Scale, and emotional distress surveys assessing depression and anxiety at preop/screening, postop and 6 week follow-up (PROMIS Emotional Distress-Anxiety Short Form, PROMIS Emotional Distress-Depression Short Form), as well as a Neuro-QOL Short Form v1.1 - Satisfaction with Social Roles and Activities .