Low-dose ketamine failed to spare morphine after a remifentanil-based anaesthesia for ear, nose and throat surgery

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.

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.

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.

Low-dose ketamine added to a remifentanil-based propofol anaesthesia did not reduce morphine consumption after major ENT surgery.