The prevention of ketamine dreams

Surgical anaesthesia was induced with a 200–250 mg dose of ketamine given intravenously to each of 100 adult patients premedicated with nitrazepam 10 mg and droperidol 20 mg taken orally two hours before the injection of ketamine. Surgical operations were then performed with additional doses of ketamine, inhalational agents or pancuronium relaxant: 50 of the patients were maintained with inhalational agents and spontaneous breathing after the ketamine induction; 25 were maintained with intermittent supplementary doses of ketamine and spontaneously breathed air or oxygen; and 25 were fully curarized (pancuronium) for abdominal surgery and were mechanically ventilated with air or oxygen and anaesthesia was maintained with supplementary doses of ketamine 100 mg intravenously at 10-minute intervals. Careful postoperative interrogation of each patient revealed that all were anaesthetized throughout the period of surgery. The nitrazepam-droperidol mixture suppressed the dreams and mental agitation associated with the recovery from ketamine anaesthesia in adults. The mixture also suppressed the muscular catatonia sometimes precipitated by ketamine. Plethysmographic studies showed that ketamine causes dilatation of the alpha blood vessels, constriction of the beta blood vessels, and blocks the reflex alpha adrenergic vasoconstrictive reaction to surgical trauma.

Use of droperidol and fentanyl for analgesia and sedation in primates

A combination of droperidol and fentanyl produces qualitatively similar pharmacologic effects in dogs and primates. Unlike the dog, however, primates did not appear to respond to auditory stimuli. As a result of the analgesic and sedative or tranquil state produced in primates, the animals were easily handled and tolerant of painful stimuli. The principal desirable features of the combination were high analgesic and sedative potency and a rapid onset of action following intramuscular administration. High doses produced respiratory depression. However, this effect was easily reversed by administering nalorphine hydrochloride.