RHYTHM CHANGES DURING RESUSCITATION FROM VENTRICULAR-FIBRILLATION IN RELATION TO DELAY UNTIL DEFIBRILLATION, NUMBER OF SHOCKS DELIVERED ANDSURVIVAL

Aim: To describe rhythm changes during the initial phase of resuscitat ion from ventricular fibrillation in relation to the interval between collapse and defibrillation, to survival and to bystander-initiated ca rdiopulmonary resuscitation (CPR). Patients: All patients who suffered out-of-hospital cardiac arrest between 1980 and 1992, who were reache d by the emergency medical service system (EMS), in whom resuscitation attempts were initiated and who were found in ventricular fibrillatio n. Results: In all, 1216 patients were included in the study. Among pa tients who converted to a pulse-generating rhythm after the first defi brillation (n = 119) were 56% discharged from hospital as compared wit h 6% among patients who converted to asystole. The corresponding figur es after the third defibrillation were 49% and 2%, respectively, and a fter the fifth defibrillation 28% and 7%, respectively. Among patients in whom the first defibrillation took place less than 5 min after col lapse, 28% directly converted to a pulse-generating rhythm as compared with 3% when the first defibrillation took place 12 min or more after collapse. Conclusion: Among patients who suffer out-of-hospital cardi ac arrest and are found in ventricular fibrillation, there is a strong relationship between survival and initial rhythm changes after defibr illation. These rhythm changes are directly related to the interval be tween collapse and the first defibrillation. (C) 1997 Elsevier Science Ireland Ltd.