Defibrillation

Double Sequence External Defibrillation for Refractory Shockable Rhythm

Last Full Review: American Red Cross Scientific Advisory Council 2023; ILCOR 2023

Double sequential external defibrillation and vector change defibrillation have been proposed as an option for patients who remain in refractory ventricular fibrillation (VF) following out-of-hospital cardiac arrest. Is there evidence to support the routine use of these extended defibrillation techniques, compared with standard manual defibrillation for cardiac arrest with a shockable rhythm?

Evidence Summary

A 2023 International Liaison Committee on Resuscitation (ILCOR) systematic review and Consensus on Science with Treatment Recommendations (CoSTR) (Ohshimo et al. 2023; Berg et al. 2023) evaluated the use of double sequential external defibrillation, compared with a standard defibrillation strategy for adults with in-hospital cardiac arrest or out-of-hospital cardiac arrest and a shockable rhythm (VF or pulseless ventricular tachycardia [VT]). This was an update of a 2020 ILCOR systematic review (Deakin et al. 2020, 24). One cluster randomized controlled trial (RCT) (Cheskes et al. 2022, 1947) was identified enrolling patients with out-of-hospital cardiac arrest meeting inclusion criteria, including the pilot trial (Drennan et al. 2020, 977) from the original 2020 systematic review. In the cluster RCT, both double sequential external defibrillation and anterior-posterior vector change defibrillation were compared with standard anterolateral defibrillation. For the use of double sequential external defibrillation compared with standard defibrillation, the double sequential external defibrillation group (n=261) showed an improved rate of return of spontaneous circulation (ROSC) (46.4% versus 26.5%, aRR 1.72; 95% CI, 1.22–2.42); improved survival to hospital discharge (30.4% versus 13.3%; aRR 2.21; 95% CI, 1.33–3.67); and improved functional outcome (modified Rankin score of 0-2) at hospital discharge (27.4% vs. 11.2%; aRR 2.21; 95% CI, 1.26–3.88). The same trial (Cheskes et al. 2022, 1947) enrolled 280 patients for a comparison of vector change defibrillation against standard defibrillation. Improved survival to hospital discharge was shown with the vector change group compared with standard defibrillation (21.7% versus 13.3%, aRR 2.21; 95% CI, 1.01–2.88), but significant improvement in functional survival at discharge or in ROSC was not demonstrated. This trial was not able to compare double sequential external defibrillation with vector change defibrillation.

The ILCOR treatment recommendations have changed from 2020, when a weak suggestion was made against the routine use of double sequential external defibrillation strategy in comparison to a standard defibrillation strategy for cardiac arrest with a shockable rhythm. The 2023 treatment recommendations suggest that a double sequential external defibrillation strategy or a vector change defibrillation strategy may be considered for adults with cardiac arrest who remain in VF or pulseless VT after three or more consecutive shocks (Ohshimo et al. 2023).  If a double sequential external defibrillation strategy is used, it is suggested that the approach is like that in the trial, with a single operator activating the defibrillators in sequence. The review also notes the importance of ensuring correct pad placement for standard defibrillation before progressing to double sequential external defibrillation or vector change defibrillation, and that pads be placed to anatomically encompass the heart, with one pad below the right clavicle, just to the right of the upper sternal border, and the other with the center of the pad in the left midaxillary line. Adequate contact must be made at the pad-skin interface to optimize energy delivery. It is also not clear from the study data whether the vector change or the double sequential external defibrillation using vector change in addition to standard defibrillation led to the beneficial outcomes (Ohshimo et al. 2023; Berg et al. 2023).

A review of the 2023 CoSTR by ILCOR was completed by the American Red Cross Scientific Advisory Council (American Red Cross Scientific Advisory Council Resuscitation: 2023) with discussion of the single, available double sequential external defibrillation study and methodological concerns. The American Red Cross Scientific Advisory Council Adult Resuscitation Subcouncil review of the updated ILCOR CoSTR concluded that the evidence from the single RCT is not strong enough to justify a change from current recommendations against routine use of double sequential external defibrillation, to recommending that double sequential external defibrillation may be considered for adults with cardiac arrest who remain in VF or pulseless VT after three or more consecutive shocks.

Methodological flaws identified in the single study included a small sample size, premature termination of enrollment and a smaller-than-expected primary outcome. Sensitivity analyses included in the available trial did not demonstrate a difference in outcomes with double sequential external defibrillation when patients were analyzed by treatment received, rather than intent to treat (randomization group). Reasons why certain patients received a defibrillation strategy other than that to which they were randomized are not known. All preceding scoping and systematic reviews were negative for a clinical benefit from double sequential external defibrillation. In addition, it is unclear if near-perpendicular vectors are the potential reason for the study findings versus simply applying defibrillator pads correctly or the ability to deliver a higher quantity of electrical current. The American Red Cross Scientific Advisory Council consensus is that there is insufficient evidence at present time to recommend the routine use of double sequential external defibrillation or vector change in either the in-hospital or out-of-hospital population.

Insights and Implications

In discussion, the American Red Cross Scientific Advisory Council emphasized the need to ensure a correct pad placement (anatomically encompassing the heart) and pad-skin interface before defibrillation. This is a new good practice statement. A systematic review and network meta-analysis published after the ILCOR and American Red Cross Scientific Advisory Council reviews included seven RCTs and comparative observational studies, finding similar odds of survival to hospital discharge, favorable neurological outcome and ROSC with use of double sequential external defibrillation and vector change defibrillation compared with standard defibrillation (Abuelazm et al. 2023, e13075).

Additional large-scale RCTs are needed. While the Red Cross does not recommend the routine use of double sequential external defibrillation for refractory VF or pulseless VT, it is recognized that some healthcare professionals may consider its use on a case-by-case basis when no further treatment options exist, and with consideration of operational feasibility, local institutional policies and resource availability.