A randomised, controlled study of peri-operative low dose s(+)-ketamine in combination with postoperative patient-controlled s(+)-ketamine and morphine after radical prostatectomy

In a randomised, double-blind prospective study we compared the effects on postoperative pain and analgesic consumption of intra-operative s(+)-ketamine (100 μg.kg−1 bolus and a continuous infusion of 2 μg.kg−1.min−1) followed by postoperative patient-controlled analgesia with morphine (1 mg per bolus) plus s(+)-ketamine (0.5 mg per bolus), or intra-operative saline followed by postoperative patient-controlled analgesia morphine (1 mg per bolus) alone. A total of 28 male patients undergoing radical prostatectomy were studied. Morphine consumption, pain scores, pressure algometry and adverse effects were recorded for 48 h after surgery. Cumulative morphine consumption was significantly lower in the ketamine/morphine group (47.9 ± 26.2 mg) than in the saline/morphine group (73.4 ± 34.8 mg; p = 0.049). Pain scores at rest were significantly lower in the ketamine/morphine group across the 48-h study period (p = 0.01). No significant differences were found in pressure algometry measurements or the occurrence of adverse effects.