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Refractory Ventricular Fibrillation – What’s the Best Defibrillation Strategy?

December 23, 2022

Written by Nickolas Srica

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For the treatment of refractory ventricular fibrillation (VF) in out-of-hospital cardiac arrest, survival to hospital discharge was more common among patients who received double sequential external defibrillation (DSED) and vector-change (VC) defibrillation than those who received standard defibrillation. 

Why does this matter?
Out-of-hospital cardiac arrest (OHCA) is a common cause of unexpected morbidity and death in North America, and further defibrillation attempts without modification on many of these patients who remain in refractory ventricular fibrillation (VF) after multiple shocks are often unsuccessful. Could modification of defibrillation strategy lead to improved survival to hospital discharge for refractory VF?

Some doubly shocking results here…
This was a three-group, cluster-randomized controlled trial with mandatory crossover into each of the three treatment groups (standard defibrillation, VC defibrillation, and DSED) at least once in six paramedic services in Canada. It included 405 patients aged 18 or older who suffered OHCA with refractory VF (i.e. ongoing VF after 3 standard defibrillation attempts/rounds of CPR) of presumed cardiac cause.

Standard defibrillation was performed with anterolateral pad placement. VC defibrillation meant the pads were changed to anterior-posterior placement after 3 shocks. DSED meant a second set of anterior-posterior pads was placed in addition to the standard pads so a second shock from a second device could occur closely (<1 second) after the first.

The primary outcome was survival to hospital discharge. 38 patients (30.4%) in the DSED group survived to hospital discharge compared with 18 (13.3%) in the standard group, RR 2.21 (95%CI 1.33-3.67). This outcome occurred in 31 patients (21.7%) in the VC group, RR 1.71 (95%CI 1.01-2.88). Secondary outcomes – termination of VF, return of spontaneous circulation (ROSC), and a good neurologic outcome at hospital discharge – were also more common with DSED.

Overall, this seemed to be a very well-run trial, despite some limitations in study power and potential confounding, and is one that just might make me think about DSED next time I’m faced with refractory VF. No devices were harmed in the making of this trial.

Another Spoonful
Check out this short video from the article for a quick rundown of the key points and further clarification on the defibrillation techniques used!

Source
Defibrillation Strategies for Refractory Ventricular Fibrillation. N Engl J Med. 2022 Nov 6. doi: 10.1056/NEJMoa2207304. Online ahead of print.

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