Peroperative ketamine and morphine for postoperative pain control after lumbar disk surgery

Background: Ketamine, a N-methyl-D-aspartate receptor antagonist, may reduce postoperative opioid demand and improve postoperative analgesia. Methods: Sixty-nine patients scheduled for lumbar disk surgery under general anaesthesia were enrolled in a randomised, doubleblind study comparing three analgesic combinations that were started before surgical incision: morphine 0.1 mg kg(-1) alone (group M; n = 23); ketamine 0. 15 mg kg(-1) alone (group K; n = 22); and a combination. of morphine 0. 1 mg kg(-1) with ketamine 0. 15 mg kg(-1) (group KM; n = 23). Postoperatively patient-controlled analgesia was provided with intravenous morphine. Morphine consumption was assessed during 24 H, and pain scores were measured using a visual analogue scale (VAS) at rest and on mobilisation, during the first two postoperative days. Results: In group KM, less i.v. morphine was administered in the post anaesthesia care unit than in group M (median [range]: 0 mg [0-2] vs. 7 mg [6-9], P = 0.009). Cumulative 24 H morphine consumption was reduced by 57% in group KM vs. group M, and by 48% in group KM vs. group K. Postoperative VAS scores were lower in group KM vs. groups K and M. Maximal VAS score on mobilization was reduced in group KM compared to groups K and M (38 mm [35-45] vs. 52 mm [48-59] and vs. 59 mm [55-64], in groups KM, K and M, respectively, P = 0.05 and P = 0.002). The incidence of postoperative nausea and vomiting was decreased in group KM compared to group M (21.7% vs. 43.5%, P = 0. 00 1). Conclusion: Ketamine small-dose, combined with morphine improves postoperative analgesia and reduces opioid-related side effects in lumbar disk surgery. (C) 2005 European Federation of Chapters of the International Association for the Study of Pain. Published by Elsevier Ltd. All rights reserved.