Rhythm changes during resuscitation from ventricular fibrillation

Defibrillation of patients with primary ventricular fibrillation (VF) results in a variety of rhythm changes. We analysed these changes in rhythm in 200 patients, using the American Heart Association's recommendation of two defibrillations prior to drug therapy. Sixty-three (31.5%) patients were immediate survivors with 38 (19%) being discharged from hospital alive. There was no difference between the age of immediate survivors (66.5 years, S.D. = 11.2) and non-survivors (68.3 years, S.D. = 13.7, P = 0.37). Immediate survivors were significantly more likely to be discharged alive from hospital if they were younger (70.0 years, S.D. 8.5 vs. 62.1 years, S.D. 15.8, P = 0.014). Increasing delays to the initiation of basic life support (CPR) and to defibrillation were associated with significantly less likelihood of cardioversion to sinus rhythm (P < 0.005 and P < 0.002, respectively). Those patients who stayed in VF were not more likely to be defibrillated into asystole or electro-mechanical dissociation. Seventeen percent (34) of patients were defibrillated to sinus rhythm after the first defibrillation and 14% (19) after the second, with similar hospital discharge rates (62% and 58%, respectively). Sixty percent (32) of patients in sinus rhythm, after two defibrillations, were discharged alive, compared to only 4% (6) of those patients not in sinus rhythm after two defibrillations. Our data provide new information on rhythm changes during resuscitation and supports the need for the earliest possible initiation of basic life support and defibrillation to improve survival from cardiac arrest due to ventricular fibrillation.