Fixed vs. Escalating Energy Levels for Biphasic Defibrillation
Escalating energy levels result in higher rates of conversion.

Recent American Heart Association guidelines endorse the use of biphasic waveform technology for treatment of cardiac arrest patients with ventricular fibrillation (VF) or pulseless ventricular tachycardia. However, use of escalating energy levels is not currently recommended. In a manufacturer-funded, multicenter, randomized, controlled trial, 211 patients with out-of-hospital cardiac arrest received one or more shocks delivered by biphasic automated external defibrillators randomly programmed to provide fixed lower energy (150-150-150 J) or escalating higher energy (200-300-360 J).

Rates of conversion to an organized rhythm were the same for first shocks of either 150 or 200 J. However, among the 106 patients who required subsequent shocks, the conversion rate was significantly higher with the
escalating higher-energy regimen than with the fixed lower-energy regimen (36.6% vs. 24.7%). The authors conclude that patients with VF benefit from higher-energy levels when multiple shocks are required.

Comment: This study -- the first randomized, controlled clinical trial to compare these energy regimens for biphasic defibrillation -- shows a significant improvement in rhythm conversion with an escalating higher-energy regimen. Even before larger trials determine whether this regimen leads to overall improvement in patient outcomes, it seems reasonable to consider escalating energy for patients who require multiple
shocks for refractory VF.

-- Aaron E. Bair, MD, FAAEM, FACEP

Published in Journal Watch Emergency Medicine April 27, 2007


Stiell IG et al. BIPHASIC Trial: A randomized comparison of fixed lower versus escalating higher energy levels for defibrillation in out-of-hospital cardiac arrest. Circulation 2007 Mar 27; 115:1511-7. (Subscription may be required) (Free)