Delayed defibrillation is common and is associated with lower rates of survival after in-hospital cardiac arrest, according to a study published in today’s issue of the New England Journal of Medicine.
Paul S. Chan, MD, from Saint Luke's Mid-America Heart Institute, Kansas City, Mo., and the University of Michigan division of cardiovascular medicine in Ann Arbor, Mich., and colleagues, identified 6,789 patients who suffered cardiac arrest due to ventricular fibrillation or pulseless ventricular tachycardia at 369 hospitals participating in the American Heart Association National Registry of Cardiopulmonary Resuscitation. Using multivariable logistic regression, the researchers identified characteristics associated with delayed defibrillation. They then examined the association between delayed defibrillation (more than two minutes) and survival to discharge after adjusting for differences in patient and hospital characteristics.
The authors found that the overall median time to defibrillation was one minute (interquartile range, greater than one to three minutes), and delayed defibrillation occurred in 2,045 patients (30.1 percent). Characteristics associated with delayed defibrillation included black race, non-cardiac admitting diagnosis and occurrence of cardiac arrest at a hospital with fewer than 250 beds, in an unmonitored hospital unit, and during after-hours periods (5 p.m. to 8 a.m., or weekends).
The researchers found that delayed defibrillation was associated with a significantly lower probability of surviving to hospital discharge (22.2 percent vs. 39.3 percent when defibrillation was not delayed). In addition, a graded association was found between increasing time to defibrillation and lower rates of survival to hospital discharge for each minute of delay.
Expert guidelines advocate defibrillation within two minutes after an in-hospital cardiac arrest caused by ventricular arrhythmia, and the findings of the researchers support this proposal.