The question of whether double sequence external defibrillation (DSED) improves outcomes in cardiac arrest scenarios, particularly in patients experiencing refractory ventricular fibrillation (VF), is an area of growing interest in emergency medicine. Current literature suggests that DSED may offer a novel approach that could enhance resuscitation success rates, especially in challenging cases where traditional defibrillation has failed. DSED maybe of more importance in those patients that have not converted after the first or second defibrillation.
Refractory ventricular fibrillation poses significant challenges, as approximately 25% of patients remain fibrillating after three defibrillation attempts (Nichol, 2025). A study by Kim et al. indicated that employing two simultaneous shocks through DSED could create duel electrical vectors, thus depolarizing more myocardium than standard defibrillation, potentially leading to improvements in return of spontaneous circulation (ROSC) and overall neurologic outcomes (Kim et al., 2020). This is supported by findings from Ross et al., who documented a ROSC rate of 57.1% and a rate of neurologically intact survival of 28.6% in cases utilizing the DSED approach (Ross et al., 2016). In addition, a systematic review highlighted the efficacy of DSED and vector change defibrillation as promising strategies for patients who do not respond to conventional defibrillation measures (Abuelazm et al., 2023).
Despite the promising outcomes associated with DSED, practical considerations must also be addressed. For instance, Alexandrou et al. noted that delays in shock delivery with the DSED setup could prolong resuscitation efforts by an average of approximately 13.7 seconds compared to standard methods, potentially affecting outcomes during cardiac arrest (Alexandrou et al., 2025). Therefore, while the increased depolarization mechanics of dual shocks could yield enhanced outcomes, these logistical hurdles must be considered in the overall assessment of DSED efficacy.
Furthermore, ongoing studies, such as the DOSE VF trial, aim to rigorously evaluate the feasibility and safety of DSED compared to traditional practices (Drennan et al., 2020). Preliminary findings from case studies have reported successful resuscitations with DSED methods, affirming its status as a potential intervention for refractory VF (Park et al., 2021).
In summary, the current body of literature indicates that double sequence external defibrillation improves outcomes for patients experiencing refractory ventricular fibrillation during cardiac arrest, with higher ROSC rates and neurological recovery reported in various studies. Nevertheless, practical concerns regarding execution time and the necessity for additional equipment should be considered in locations where resuscitation equipment is not easily available.
References:
- Abuelazm, M., Ghanem, A., Katamesh, B., Hassan, A., Abdalshafy, H., Seri, A., … & Abdelazeem, B. (2023). Defibrillation strategies for refractory ventricular fibrillation out‐of‐hospital cardiac arrest: a systematic review and network meta‐analysis. Annals of Noninvasive Electrocardiology, 28(5).
https://doi.org/10.1111/anec.13075
- Alexandrou, K., Khattab, E., & Asimakopoulou, E. (2025). Enhancing patient safety in refractory ventricular fibrillation: a systematic review of double sequential and vector change defibrillation barriers. Healthcare, 13(20), 2645.
https://doi.org/10.3390/healthcare13202645
- Drennan, I., Dorian, P., McLeod, S., Pinto, R., Scales, D., Turner, L., … & Cheskes, S. (2020). Double sequential external defibrillation for refractory ventricular fibrillation (dose vf): study protocol for a randomized controlled trial. Trials, 21(1).
https://doi.org/10.1186/s13063-020-04904-z
- Kim, H., Lee, K., Jo, Y., Lee, J., Kim, Y., Kim, J., … & Oh, Y. (2020). Refractory ventricular fibrillation treated with double simultaneous defibrillation: pilot study. Emergency Medicine International, 2020, 1-6.
https://doi.org/10.1155/2020/5470912
- Nichol, G. (2025). Scientific priorities related to the use of double sequential external defibrillation in patients with refractory cardiac arrest: report from a multistakeholder thinktank. Journal of the American Heart Association.
https://doi.org/10.1161/jaha.125.044130
- Park, S., Kim, J., Cho, Y., Lee, E., Shim, B., & Yoon, Y. (2021). Successful resuscitation of refractory ventricular fibrillation with double sequence defibrillation. Acute and Critical Care, 36(1), 67-69.
https://doi.org/10.4266/acc.2020.00122
- Ross, E., Redman, T., Harper, S., Mapp, J., Wampler, D., & Miramontes, D. (2016). Dual defibrillation in out-of-hospital cardiac arrest: a retrospective cohort analysis. Resuscitation, 106, 14-17.
https://doi.org/10.1016/j.resuscitation.2016.06.011