Shockingly Ineffective – Double Sequential Defibrillation for Refractory Vfib and Vtach
January 28, 2019
Written by Sam Parnell
Prehospital double sequential defibrillation (DSD) was not associated with improved survival for out-of-hospital cardiac arrest (OHCA) patients with refractory ventricular fibrillation or pulseless ventricular tachycardia.
Why does this matter?
DSD consists of attaching two defibrillators to a patient and delivering simultaneous defibrillations. Available evidence for DSD is limited and off-label, not to mention it may damage the defibrillator. See this study. So, what does the evidence say about using DSD for refractory VF or pVT during prehospital cardiac arrest?
Twice the shock – equally ineffective
This was a matched case-control study of patients with OHCA and refractory VF and pVT, defined as three standard 200J defibrillations without return of spontaneous circulation (ROSC) or conversion to a non-shockable rhythm. Sixty-four cases of survival to hospital admission were matched with sixty-four controls that did not, and there was no significant difference (48% DSD vs 50.5% conventional, OR 0.91, p>0.99). Also, there was no difference in prehospital ROSC, survival to hospital discharge, or neurologically intact survival at discharge between DSD and conventional therapy. This was a small, single center, case-control study that has several limitations including the possibility of selection bias, inability to control for CPR quality, and a protocol that leaves the decision of whether or not to administer DSD after the third shock to the lead paramedic.
However, it is also the largest study to date, and the results correlate with a recent metanalysis of two retrospective studies in press with Resuscitation that showed no statistically significant difference in survival to discharge or other outcomes. DSD may be, as Slovis says, a crowd pleaser, but the available evidence has not shown it to be effective. It may also damage the defibrillator, void the warranty, place future patients at risk if the defibrillator fails, and cost a lot of money. Think twice…and maybe just shock once.
Prehospital Double Sequential Defibrillation: A Matched Case-Control Study. Acad Emerg Med. 2018 Dec 10. doi: 10.1111/acem.13672. [Epub ahead of print]
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Reviewed by Clay Smith