Double Sequential External Defibrillation for Refractory Ventricular Fibrillation: It ’s All About the Timing

Double sequential external defibrillation (DSED) for refractory ventricular fibrillation (VF) has generated a great deal of interest, excitement and confusion as a treatment option for patients who present in refractory VF. Our research team was delighted by the invitation by JEMS to describe our findings from the 2019 NAEMSP annual meeting in this edition of the journal. In this article, we will also discuss controversies surrounding the practice of DSED and highlight some of the previous research into the effectiveness of DSED for refractory VF. The Background DSED has been studied for decades in the electrophysiology lab for patients in both refractory atrial fibrillation and refractory VF.1-8 Why do ongoing defibrillation attempts in refractory VF fail to terminate VF? The reason is believed to be at least twofold. As VF persists, the energy required to defibrillate increases as a function of time, due to ischemia induced changes in conduction velocity and refractoriness. Second, if the initial shocks fail to terminate VF, the energy supplied to the fibrillating heart may be insufficient to terminate VF. Finally, as resuscitation progresses, ongoing hypoxia, acidosis and exogenous and endogenous catecholamine surges increase myocardial oxygen consumption, making the ventricle more difficult to successfully defibrillate.1-4 Defibrillatory shocks effectively depolarize most of the fibrillating myocardium and allows coordinated muscle contraction of the heart to begin. When ...
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