![]() It is also the more likely method of administration in clinical setting. 8,18 This is where DD gets its alternate name of “Double Sequential Defibrillation (DSD)”. Setting Up Theory: It is suggested that the first shock lowers the defibrillation threshold, thus increasing the second shock’s success in converting any remaining fibrillating myocytes.Furthermore, several studies have shown safety in patients receiving up to 720 Joules (J) of monophasic energy for conversion of RVF and atrial fibrillation. Lack of real-time measuring devices and subsequent delay in human response times makes it difficult to consistently perform true simultaneous defibrillation in the clinical setting. 4,13-16 This is why DD is often termed “Double Simultaneous Defibrillation (DSiD)”. More Power Theory: Several studies have shown that higher energy has improved success on subsequent defibrillation.There are three main hypothesized theories as to why DD is effective: 4,9-12 There is currently no evidence suggesting sequential or simultaneous is more effective. 2 (Figure 1)ĭD can either be simultaneous (Figure 2) or sequential (Figure 3), depending on the duration of the defibrillation potential and the intershock interval between the two defibrillator shocks. More importantly, 11 of those patients who received DD were discharged with a Cerebral Performance Category (CPC) score of 2 or less, indicating good neurologic outcomes. In a large literature review, DD terminated RVF in 77% of the 39 cases. Multiple case reports have shown the effectiveness of a second defibrillator in terminating RVF. 1-5 RVF depends on multiple variables: time in VF, body habitus (despite animal models showing inverse relationship with defibrillation), total defibrillator energy used, chronic lung disease, and use of antiarrhythmic agents. One consistent description is persistent VF without response to three or more defibrillations. Refractory ventricular fibrillation (RVF)’s definition varies. ACLS, however, says nothing about it, let alone how to do it or if it even works. At this point, someone in the resuscitation team suggests performing double defibrillation (DD). VF is seen yet again, and a seventh shock is administered. Calcium gluconate is given, in addition to another dose of epinephrine, all while good-quality CPR is being continued. On the next pulse check, VF is seen again, so another shock is delivered. CPR is continued, and amiodarone is administered. VF is noted on the hospital monitor, and a fifth shock is delivered. A total of three shocks, and two doses of epinephrine were given in route, all with on-going CPR. The EMS crew arrives and states that the initial rhythm was ventricular fibrillation (VF). Bystander hands-only CPR was performed, and one shock was delivered by an automated external defibrillator (AED). EMS calls ahead with notification of a 54-year-old male who collapsed while walking on a college campus.
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