The acute cardiovascular changes and adrenergic blockade by droperidol in man.

This study shows the effect of droperidol on the arterial pressure in patients who were undergoing heart surgery with cardiopulmonary bypass, translumbar aortography or vascular surgery. Intravenous injection of droperidol caused a transient fall in systemic arterial pressure. Direct injection into the aorta caused an immediate reduction in arterial pressure which was due to the direct action of the droperidol on the peripheral vessels. Injection into the oxygenator during cardiopulmonary bypass caused a transient reduction in arterial pressure, and when the effect of droperidol was maximal, peripheral vasoconstriction produced by adrenaline and noradrenaline was completely suppressed or severely attenuated for a period sometimes exceeding 10 minutes. The evidence presented suggests that, in man, droperidol may be an adrenergic blocking agent and does not contradict the hypothesis that its action is mediated by blockade of alpha-adrenergic receptors.