The Use of Dantrolene to Improve Analgesia in Posterior Lumbar Surgery

Inclusion Criteria * 18 - 80 years of age (inclusive) * Presenting to the study hospital for lumbar decompression and/or fusion (instrumented fusion of the lumbar spine \< 4 levels) under general anesthesia, and scheduled for same-day admission or in-patient admission * American Society of Anesthesiologists (ASA) Category 1, 2 or 3 Exclusion Criteria * Known allergy to Dantrolene, morphine or other opioids, benzodiazepines that causes a reaction of hives, anaphylaxis, shock, unconsciousness/fainting, rashes/blisters, irregular heartbeat, fever, swelling, shortness of breath, wheezing, serum sickness, drug induced anemia, drug reaction with eosinophilia, and systemic symptoms, or nephritis * Oxygen saturation \< 94% * Patient being treated with any of the following medications:Non-dihydropyridine Calcium Channel Blockers including verapamil, Estrogen therapy * Current or past medical history of any of the following: hepatic impairment (including history of transplant), renal impairment or chronic renal disease (including history of transplant), chronic alcohol abuse, chronic respiratory disease (i.e. chronic hypoxia or hypercapnia, COPD) * Recent history of aspiration (within the last 3 months) * Patients with any history of neuromuscular dysfunction * History of obstructive sleep apnea * Weight \> 140 kg * Currently pregnant * Actively breastfeeding * Inability to provide written informed consent