Double sequential external defibrillation for refractory ventricular fibrillation out-of-hospital cardiac arrest: A systematic review and meta-analysis

Background: Double sequential external defibrillation (DSED) is a novel intervention which has shown potential in the management of refractory ventricular fibrillation (VF). This review aims to identify the literature surrounding the use of DSED in out-of-hospital refractory VF and assess whether this intervention improves survival outcomes. Methods: The databases Ovid Medline, EMBASE, CINAHL, SCOPUS and the Cochrane Library were searched from their commencement to January 29th 2018. Google (scholar) was also searched for grey literature. We combined MeSH terms and text words for DSED in refractory VF and included studies that used an interventional or observational design. Study quality was assessed using the Newcastle-Ottawa Scale. A random effects model using the DerSimonian & Laird method was used to calculate pooled ORs and 95% CIs. Results: The search yielded 5351 unique records, of which two retrospective studies met the eligibility criteria. No randomised controlled trials were identified. The pooled population included 499 patients of which 19% (n = 95) received DSED and 81% (n = 404) were managed with standard resuscitation protocols. Confirmation of DSED was self-reported by paramedics. Neither study adjusted for confounding factors or baseline characteristics across the study groups. The definition of refractory VF and the protocol for DSED use differed across studies. Over half of cases were witnessed cardiac arrests (58.7%, n = 293) and bystander CPR was initiated in 53.3% (n = 266) of cases. In the meta-analysis, DSED had no effect on survival to hospital discharge (OR 0.69, 95% CI: 0.30, 1.60), event survival (OR 0.98, CI: 0.59, 1.62) or ROSC (OR 0.86, 95% CI: 0.49-1.48). Conclusion: The effectiveness of DSED remains unclear. Further well-designed prospective studies are needed to determine whether DSED has a role in the treatment of refractory VF.