Delaying a second attempt at defibrillation to allow time for chest compressions, as revisions in the 2005 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care recommend, is not associated with improved survival or better outcomes, according to two studies published April 6 online ahead of print in BMJ. 

In the first study, lead author Steven M. Bradley, MD, MPH, and colleagues studied the time between the first and second defibrillation attempts among 2,733 patients undergoing cardiac arrest in 172 U.S. hospitals. They found that a deferred second defibrillation (more than 1 minute between the first and second defibrillation) was attempted in more than 50% of patients in 2012, which doubled from approximately 25% in 2004, but the deferred defibrillation was not associated with improved survival. 

In the second study, senior author Michael W. Donnino, MD, and fellow investigators used data from the same registry as the first study for nearly 3,000 patients in cardiac arrest at more than 300 U.S. hospitals. They found that 51% of patients received epinephrine within two minutes after the first defibrillation, and this intervention was associated with decreased odds of survival to hospital discharge and of return of spontaneous circulation and survival to hospital discharge with good functional outcome. The American Heart Association recommends epinephrine after the second defibrillation. 

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