Combined infusions of morphine and ketamine for postoperative pain in elderly patients.

The value of using a combined infusion of morphine with a variable dose of ketamine for postoperative analgesia following upper abdominal surgery was assessed in a double-blind randomised study of 40 elderly patients. Four groups of 10 patients received an infusion of morphine at 1 mg.h-1, either alone, or combined with ketamine at a rate of 5, 10 or 20 mg.h-1. The addition of ketamine to a continuous infusion of morphine did not significantly improve either analgesia or postoperative lung function. Increasing the dose of ketamine resulted in an increased incidence of postoperative dreaming (p < 0.01).