Background: Ketamine has been claimed to prevent acute opioid tolerance and hyperalgesia following acute exposure to opioids and its use has been proposed to decrease postoperative morphine consumption.
Methods: We conducted a randomized, double-blind, controlled study to evaluate the effect of intravenous (i.v.) ketamine on postoperative pain for 48 h after major ear, nose and throat (ENT) surgery. Thirty-one patients received i.v. ketamine 0.15 mg kg(-1) before induction and 2 microg kg(-1) min(-1) during anaesthesia, and 31 patients were administered placebo in a similar manner. Anaesthesia was standardized with remifentanil and propofol, but without nitrous oxide. Standardized postoperative analgesia included paracetamol, methylprednisolone and morphine administered via a patient controlled analgesia (PCA) device.
Results: Intra-operative remifentanil consumption was not different between the ketamine group (0.25 +/- 0.07 microg kg(-1) min(-1)) and the control group (0.22 +/- 0.07 microg kg(-1) min(-1)). In the postoperative period, both groups experienced an identical pain course evolution. Cumulative morphine consumption was not significantly different between groups: at 24 h it was 33.3 +/- 14.9 with ketamine and 31.9 +/- 15.3 mg in controls, at 48h it was 40.4 +/- 20.6 mg with ketamine and 42.5 +/- 25.9 mg in controls.
Conclusion: Low-dose ketamine added to a remifentanil-based propofol anaesthesia did not reduce morphine consumption after major ENT surgery.