Out-of-hospital cardiac arrest is a commonly encountered entity in U.S. emergency departments (EDs), with statistics reporting more than 356,000 out-of-hospital cardiac arrests per year.1 Ventricular tachycardia (VT) and ventricular fibrillation (VF) represent the most common initial rhythms for patients presenting to the ED in out-of-hospital cardiac arrest, as well as for patients who develop cardiac arrest while in the ED.2,3 In general, patients who develop cardiac arrest with an initial rhythm of VT or VF tend to have favorable outcomes compared to patients who develop cardiac arrest from either asystole or pulseless electrical activity.2 Standard management for VT and VF involves the use of electrical defibrillation, high-quality chest compressions, and epinephrine. However, between four and five percent of cases of VT or VF will be refractory to standard management, with nonperfusing arrhythmia persisting despite repeated shocks.4 Given this, more recent attention has been paid to management of refractory VT and VF, with several recent updates suggesting new strategies that can be employed by emergency physicians for such cases.
Explore This IssueACEP Now: Vol 42 – No 07 – July 2023
What is “Refractory” VT/VF?
There are some differing guidelines as to what constitutes “refractory” VT or VF. Initial guidelines defined “refractory” as VT or VF occurring despite three shocks from a cardiac defibrillator.5 More recent literature defines “refractory” as VT or VF that is persistent or recurrent despite three shocks from a defibrillator, three rounds of epinephrine, and use of an antiarrhythmic (i.e., amiodarone or lidocaine).6
What Can I Do Outside of Repeated Shocks and Standard ACLS?
1. Change defibrillation strategy
Standard defibrillation uses pads in the anterolateral position. Modified strategies for refractory cases of VT or VF involve either moving the pads to the anteroposterior position or using two sets of pads for dual sequential external defibrillation. Prior retrospective reviews of dual sequential defibrillation showed promising results with regard to termination of refractory VF, return of spontaneous circulation, and survival to hospital discharge.8 More recently, the DOSE VF pilot study and subsequent cluster randomized control trial, Defibrillation Strategies for Refractory Ventricular Fibrillation, have demonstrated significant benefit of both anteroposterior pad placement and dual sequential defibrillation in cases of refractory VF compared to continued anterolateral shocks.9,10
To perform dual sequence defibrillation, place pads in the anterolateral and anteroposterior position. One operator should perform defibrillation in the anterolateral position, followed by another operator providing a second shock in the anteroposterior position after a delay of less than one second.
Tips for use of dual sequence defibrillation11: