Effects of ketamine versus dexmedetomidine maintenance infusion in posterior spinal fusion surgery on acute postoperative pain

BACKGROUND: One of the most challenging issues after posterior spinal fusion (PSF) surgery is providing appropriate pain control measures to enhance recovery of the patients. We aimed to compare effects of ketamine versus dexmedetomidine infusion during maintenance of anesthesia on acute postoperative pain in PSF surgery. METHODS: In a double-blinded randomized clinical trial, 87 patients candidates for PSF surgery were randomly assigned into three groups. Anesthesia protocol for all groups was the same except: the first group received 0.2 mcg/kg/h dexmedetomidine infusion, the second received 0.1 mg/kg/h ketamine infusion, and control group received normal saline infusion as a placebo. Pain intensity by VAS scale and level of sedation by Ramsey scale were assessed, and amount of opioid prescribed after surgery was measured and compared for patients during the recovery and at 2, 4, 6, 12, and 24 h after surgery in three groups, and hypotension and bradycardia during operation were reported. RESULTS: There was a significant difference among the groups regarding pain intensity and amount of opioids during recovery and at 2, 4, 6, 12, and 24 h after surgery. Pain intensity and amount of opioids for ketamine and dexmedetomidine groups were significantly lower than those in the controls during recovery and at the hours after surgery. There was no significant difference regarding bradycardia and hypotension and level of sedation during recovery and at the hours after surgery. CONCLUSION: Both ketamine and dexmedetomidine infusions during maintenance of anesthesia are effective in reducing acute postoperative pain effectively after PSF surgery.