The effect of intraoperative ketamine and magnesium sulfate on acute pain and opioid consumption after spine surgery

Abstract

Ketamine and magnesium in brain act as an N-methyl-D-aspartate receptor antagonist that has been shown to be useful in the reduction of acute postoperative pain and analgesic consumption in a variety of surgical interventions. We hypothesized that combination of low dose ketamine and magnesium would reduce early postoperative opiate consumption and analgesic requirement after 6 weeks. This was a randomized, prospective, controlled-placebo trial involving elective and eligible patients undergoing lumbar spine surgery. Seventy patients in the treatment group were administered 0.5 mg/kg intravenous ketamine and 1 gram of magnesium as an intravenous bolus slowly during 3 minute before incision and 0.25 mg/kg/hr ketamine and 0,5 g/hr magnesium intravenous infusion during surgery. Seventy patients in the placebo group received saline of equivalent volume. Patients were observed for48 h postoperatively and followed up at 6 weeks. The primary outcome was 48h morphine consumption. The severity of pain was lower in the intervention group than in the placebo group during 48 hr post-operatively, morphine consumption in this group also decreased significantly during this period. Intraoperative ketamine-magnesium reduces opiate consumption in the 48-h postoperative period. This combination may also reduce pain intensity throughout the postoperative period in this patient population.