Initial defibrillatory shocks using 175 J were as effective for survival as 320 J shocks, but 320 J shocks caused a higher incidence of atrioventricular block (24% vs 9%; P<0.005).
RCT (n=249)
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 supraventricular rhythm, 30 per cent in persistent ventricular fibrillation, 26 per cent in idioventricular rhythm, and 14 per cent in asystole; P less than 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 atrioventricular block after defibrillation (24 per cent of patients receiving 320 J and 9 per cent of those receiving shocks of lower energy; P less than 0.005). Patients who survived required fewer shocks than patients who later died in the hospital (2.6 shocks as compared with 3.6; P less than 0.005). We conclude that initial defibrillatory shocks using 175 J are as safe and effective as shocks of nearly twice that energy level.
Weaver et al. (Thu,) conducted a rct in Ventricular fibrillation (n=249). Initial electrical shocks vs. 320 J was evaluated on Survival. Initial defibrillatory shocks using 175 J were as effective for survival as 320 J shocks, but 320 J shocks caused a higher incidence of atrioventricular block (24% vs 9%; P<0.005).