Survival in patients found to have ventricular fibrillation after cardiac arrest witnessed outside hospital

Since 1980 an Emergency Medical Service (EMS) system with atwo-tier ambulance service has been operating in Göteborg.During this 12-year period, all cardiac arrests outside hospitalhave been monitored. Cardiopulmonary resuscitation (CPR) trainingfor the general public began in 1985 and, by the end of 1992,125 000 persons had been trained. The aim of this study was to define the factors associated withan increased chance of survival after cardiac arrest witnessedout-of-hospital and secondary to ventricular fibrillation. The study group comprises all patients with cardiac arrest witnessedoutside hospital in Goteborg between 1980 and 1992, in whomCPR was initiated by our EMS and ventricular fibrillation observedat the first ECG recording. In a multivariate analysis of age, sex, time of collapse, intervalbetween collapse and first defibrillation, bystander-initiatedCPR, the following factors were associated with an increasedchance of being discharged from hospital: (1) Short intervalbetween collapse and first defibrillation (P<0.001); (2)Bystander-initiated CPR fP<0.001); and (3) Age (P<0.05). Among patients with an out-of-hospital cardiac arrest who werefound by the EMS personnel to have ventricular fibrillation,the predictors of survival were: interval between collapse anddefibrillation, bystander-initiated CPR and age.