Asystole and its treatment: the possible role of the parasympathetic nervous system in cardiac arrest.

Parasympathetic tone may be high during ventricular asystole because of reflex vagal stimulation from a number of sources. Eight patients in cardiac arrest were treated with cardiopulmonary resuscitation. All eight patients had ventricular asystole as the initial rhythm or as the result of defibrillation. Six patients failed to respond to 5 cc to 20 cc of 1:10,000 epinephrine intravenously (IV). In all eight cases a regular rhythm (sinus in seven, idioventricular in one) appeared within 30 seconds of administration of the last dose of atropine (1 mg to 2 mg IV). Five patients (62.5%) lived 12 hours, three (37.5%) were discharged from the hospital. These results suggest that atropine may be of value in the treatment of ventricular asystole.