Abstract P54: Initial Defibrillation versus Initial Chest Compression in a 4-minute Ventricular Fibrillation Canine Model of Cardiac Arrest
Objective: Prior laboratory and clinical studies demonstrate that chest compression preceding defibrillation of prolonged ventricular fibrillation (VF) increases the likelihood of successful cardiac resuscitation. The lower limit of VF duration at which time pre-shock chest compression provides no benefit has not been specifically studied. The purpose of this study was to compare defibrillation and cardiac resuscitation outcome between immediate initial defibrillation and initial chest compression in a 4-minute VF canine model of cardiac arrest.
Methods: VF was induced in anesthetized and instrumented canine. After 4 minutes of untreated VF, animals were randomly assigned to either shock-first group or chest-compression-first group. Animals in shock-first group received immediate single counter-shock and 200 immediate post-shock chest compressions before pulse check or rhythm reanalysis. The ratio of compression: ventilation is 30:2. The interruptions to deliver rescue breaths were eliminated in this study. Animals in chest-compression-first group were given 200 chest compressions before the single counter-shock; the other interventions were the same as in the shock-first group. In these two groups, drugs were administered according to the 2005 guidelines established by the American Heart Association (AHA), in association with the International Liaison Committee on resuscitation (ILCOR).
Results: In the shock-first group, all animals achieved restoration of spontaneous circulation(ROSC) and 10 of 12 animals survived at the 24-hour study end point. In the chest-compression-first group, 11 of 12 animals achieved ROSC and 9 of 12 animals survived at the 24-hour study end point.
Conclusions: In this 4-minute VF canine model of cardiac arrest, there is no significant difference in the priority of initial defibrillation or initial chest compression.