Attempts to control the cardiostimulatory effect of ketamine in man

Ketamine is unique among general anaesthetics in causing a rise in blood pressure, usually accompanied by tachycardia. These changes have been attributed to increased cardiac output 1’2, central sympathetic stimulation 3 and depression of baroreceptors4. Bovill and colleagues5 have shown a rise in plasma noradrenaline following ketamine and demonstrated that the blood pressure rise can be reduced, but not abolished, by the prior administration of 5mg of droperidol, a drug with mild a-adrenergic blocking activitys-8. In animal studies Traber and his colleagues9 showed a reduction in the hypertensive response to ketamine after large doses of atropine. In order to clarify the relationship between ketamine-induced changes in blood pressure and pulse rate, and to further elucidate factors involved in their aetiology a study was carried out in which 5mg propranolol or 2mg atropine were given prior to ketamine. These doses should be adequate to produce p-adrenergic 1 0 and vagal11 block respectively.