Incidence, duration and survival of ventricular fibrillation in out-of-hospital cardiac arrest patients in Sweden

The chance of survival from ventricular fibrillation (VF) is up to ten time s higher than those with other cardiac arrest rhythms. To calculate the eff ect of out-of-hospital resuscitation organisations on survival, it is neces sary to know the percentage of cardiac arrest patients initially in VF and the relationship between delay time to defibrillation and survival. Aim: To study the incidence of VF at the time of card iac arrest and on first EGG, the duration of VF and the relation between time to defibrillation and sur vival. Method: The Swedish Cardiac Arrest Registry has collected standardis ed reports on out-of-hospital cardiac arrests from ambulance organisations in Sweden, serving 60% of the Swedish population. Results: In 14 065 cases of out-of-hospital cardiac arrest collected between 1990 and 1995, resuscit ation was attempted in 10 966 cases. Incidence: The first ECG showed VF in 43% of all patients. The incidence of VF at the time of cardiac arrest was estimated to be 60-70% in all patients and 80-85% in the cases with probabl e heart disease. Duration: The estimated disappearance rate of VF was slow. Thirty minutes after collapse approximate to 40% of the patients were: in VF. Survival: Overall survival to 1 month was only 1.6% for patients with n on-shockable rhythms and 9.5% for patients found in VF. With increasing tim e to defibrillation, the survival rate fell rapidly from approximate to 50% with a minimal delay to 5% at 15 min. Conclusions: This study suggests a h igh initial incidence of VF among out-of-hospital cardiac arrest patients a nd a slow rate of transformation into a non-shockable rhythm. The survival rate with very short delay times to defibrillation was approximate to 50%, but decreased rapidly as the delay increased. (C) 2000 Elsevier Science Ire land Ltd. All rights reserved.