Postoperative analgesia and early rehabilitation after total knee replacement: a comparison of continuous low-dose intravenous ketamine versus nefopam.

The effects of nefopam and ketamine on pain control and rehabilitation after total knee replacement were compared in a prospective, double blinded study. Seventy-five patients were randomly assigned to receive a 0.2mg kg(-1) bolus of nefopam or ketamine, followed by a 120microg kg(-1) h(-1) continuous infusion until the end of surgery, and 60microg kg(-1) h(-1) until the second postoperative day, or an equal volume of saline considered as placebo. Pain scores measured on a visual analog scale at rest and on mobilization, and patient-controlled intravenous morphine consumption, were assessed during 48h. We measured the maximal knee flexion on the third postoperative day, and the delay to obtain a 90 degrees flexion. Ketamine and nefopam reduced morphine consumption (p<0.0001). Pain scores, were lower at rest and on mobilization in the ketamine group compared to the two other groups at all times of measurement. Pain score were lower in patients receiving nefopam compared to placebo, on arrival in the recovery room and at 2h. Ketamine improved knee flexion on post operative day 3 (59 degrees [33-63] vs. 50 degrees [47-55] and 50 degrees [44-55] in ketamine, placebo and nefopam groups, respectively, p<0.0002) and decreased the delay to flex the knee at 90 degrees (9.1+/-4.2 vs. 12.3+/-4.0 days, in ketamine and placebo groups, respectively, p=0.01). Ketamine produces opioid-sparing, decreases pain intensity, and improves mobilization after total knee replacement. Nefopam achieves less significant results in that circumstances.

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, double-blind 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]: 0mg [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=0.001). CONCLUSION: Ketamine small-dose, combined with morphine improves postoperative analgesia and reduces opioid-related side effects in lumbar disk surgery.