Dual Defibrillation is Highly Variable: An Analysis of Pulse Interval Delivered in Dual Defibrillation

Background: Dual defibrillation (DD) is a technique where two external defibrillators are applied with two different pad configurations and discharged to treat refractory ventricular fibrillation (RVF). Although commonly called dual sequential defibrillation (DSD), if the delivered electrical pulses overlap with no pulse interval, the shocks are actually dual simultaneous defibrillation (DSiD). Manual DD technique is not standardized and the effect that the method of activation has on the delivered pulse interval has never been studied. Objectives: This study measured the timing of four methods of DD and the resulting inter-shock intervals, frequency with which they were either DSiD or DSD, and frequency which the true DSDs delivered any previously reported optimum pulse interval. Methods: This was a single-blinded prospective evaluation of a convenience sample of volunteer physicians, nurses, and paramedics each performing DD in our simulation center on two types of defibrillators using four techniques: single operator-simultaneous with 2 hands (SOSI), two operators-simultaneous (TOSI), single operator-sequential with 1 hand (SOSE1), and single operator-sequential with 2 hands (SOSE2). Results: The four DD methods generated a variable set of pulse intervals depending on the technique and defibrillator employed. The pulse intervals ranged from 0 msec (i.e., overlapping waveforms or DSiD) to 1800 msec. Of all DD attempts, 85.9% met the definition of DSD, 14.1% were DSiD, and 49.4% delivered any one of the optimum pulse intervals previously described in the literature. SOSI and TOSI techniques resulted in DSD between 47.2 and 87.6% of the time, depending on the technique and defibrillator. Shocks delivered sequentially on purpose (SOSE2 and SOSE1) were always DSD but with widely variable pulse intervals. SOSI resulted in the shortest pulse intervals, SOSE1 resulted in the longest, and TOSI and SOSE2 were the least skewed. Conclusion: DD using the various methods currently employed produces a highly variable set of pulse intervals even within a single method. It is difficult to reach a conclusion about the efficacy of DD unless the delivered pulse interval is measured or the method of activation reproducibly produces a precise pulse interval.