In the past 3 decades, advances in the understanding of the resuscitation of cardiac arrest have provided opportunities to strengthen the links in the chain of survival. Despite the apparent progress, however, survival has remained poor. Cardiac arrest is a leading cause of mortality in the US, accounting for up to 450,000 deaths annually. Eighty percent of all cardiac arrest events are caused by the arrhythmia, ventricular fibrillation. Prompt electrical defibrillation is the only effective therapy. The time interval from collapse to attempted defibrillation is the most important determinant of outcome. The chance of survival decreases on average by approximately 10-15% for every minute that elapses prior to attempted defibrillation. Thus, methods to decrease the time interval between collapse and electrical defibrillation represent a true opportunity to improve survival from cardiac arrest.