Ventricular Defibrillation — A Comparative Trial Using 175-J and 320-J Shocks

Abstract
We compared the effects of initial electrical shocks using 175 and 320 J (joules) in 249 patients with ventricular fibrillation. Survival was unrelated to the energy level used for defibrillation. Reversion to an organized rhythm occurred in a similar proportion of both treatment groups after one or two shocks. The rhythm identified after the first shock was related to outcome (the survival rate was 42 per cent in patients with supraventhcular rhythm, 30 per cent in persistent ventricular fibrillation, 26 per cent in idioventhcular rhythm, and 14 per cent in asystole; P<0.02). Fibrillation recurred in 68 per cent of patients who had been initially defibrillated to an organized rhythm. Repeated shocks at the higher energy level resulted in a higher incidence of atrioventhcular block after defibrillation (24 per cent of patients receiving 320 J and 9 per cent of those receiving shocks of lower energy; P<0.005).