Primary objective: Defibrillation is essential for victims of sudden cardiac arrest (SCA) with ventricular fibrillation (VF), yet it does not terminate the underlying causes of VF. Prior to more definitive interventions, these same causes may result in recurrence of VF following defibrillation (refibrillation). The incidence and course of refibrillation, and its relation to patient outcomes, has not been previously described in the context of treatment of out-of-hospital SCA with biphasic waveform automated external defibrillators (AEDs).
Materials and methods: ECGs were recovered from all shocks delivered with biphasic AEDs by Basic Life Support (BLS) first responders, primarily police, in witnessed cardiac arrests occurring from December 1996 to December 2001 in the Rochester, MN public service area. Only events prior to administration of cardio-active medications were considered. Frequency and time to occurrence of refibrillation were compared in patients in relation to the progress of their resuscitation and survival.
Results and conclusions: One hundred and sixteen of 128 shocks delivered under BLS care to 49 patients with witnessed cardiac arrests presenting with VF terminated VF. Most patients (61%) refibrillated while under BLS care, many (35%) more than once. Occurrence of and time to refibrillation were unrelated to achievement of return of spontaneous circulation (ROSC) under BLS care (BLS ROSC), to survival to hospital discharge and to neurologically intact survival.