In a randomized, double-blind study with placebo,
ketamine was used as an
analgesic during
ventilator treatment in the period of recovery after major abdominal surgery. Forty patients were orally intubated and ventilated by means of a volume-controlled
ventilator. Twenty of them received an i.v. bolus of 30 mg of
ketamine followed by an 8-h infusion of 1 mg per minute. End-tidal CO2-concentration was continuously monitored and ventilation was adjusted to metabolic demands prior to assessment of
pain. If
pain relief was not adequate, the infusion rate was doubled, and if this was still not sufficient, 5 mg
injections of
ketobemidone were given i.v. If the orotracheal tube was not tolerated, the internal branch of the superior laryngeal nerve was blocked. A total of 30
injections of
ketobemidone were administered to 13 control patients, but only five were given to four
ketamine patients. Ten control and three
ketamine patients required an internal laryngeal nerve block. Dreams and
hallucinations were recalled in three patients in the control group and five in the
ketamine group. Only one control and two
ketamine patients experienced these as unpleasant. In this investigation,
ketamine infusion in a low dose appeared to offer satisfactory
analgesia and to permit tolerance of the orotracheal tube.