Intraoperative Ketamine and Magnesium Therapy to Control Postoperative Pain After Abdominoplasty and/or Liposuction: A Clinical Randomized Trial.

[PURPOSE] This study aimed to compare the effects of ketamine and ketamine associated with magnesium on opioid consumption and pain scores in patients undergoing abdominoplasty and/or liposuction compared to standard treatment.

[PATIENTS AND METHODS] A total of 63 patients were included and randomized as follows: 21 patients in the Control group, 20 patients in the Ketamine group (Ket), and 22 patients in the Ketamine-magnesium group (KetMag). The KetMag group received an IV bolus of 0.3 mg/kg of ketamine and 50 mg/kg magnesium, followed by continuous infusion of ketamine (0.15 mg/kg/h) and magnesium (10 mg/kg/h) until extubation. The Ket group received the same bolus and infusion of ketamine, together with a bolus and continuous infusion of placebo instead of magnesium. The Control group received saline instead of ketamine and magnesium. The groups were compared in morphine consumption during the first 12h, body-postoperative pain and disability scale until the 90th day, the time until the first morphine request on the PCA pump, pain scores, and the adverse effects related to the use of study drugs.

[RESULTS] The KetMag group had a lower morphine consumption by almost 50% during the first 12h than the Control and the Ket groups. In addition, the KetMag group required the first dose of morphine later than the other two groups. There were no differences in the adverse effects of the proposed treatments. Finally, multiple linear regression and a nonlinear approach analysis indicated that the Control group experienced a higher degree of pain and increased morphine consumption per hour than Ket and KetMag groups.

[CONCLUSION] Co-administration of intraoperative ketamine plus magnesium and ketamine alone are an effective and easy regime for reducing pain and opioid consumption in the postoperative period.