GENERAL CARDIOLOGY

Delayed defibrillation after in-hospital cardiac arrest: why the delay?

Prompt defibrillation after cardiac arrest with ventricular fibrillation (VF) or pulseless ventricular tachycardia (VT) has been associated with improved outcome. In an observational study of 369 hospitals participating in the National Registry of Cardiopulmonary Resuscitation, Chan et al identified 6789 patients who had an in-hospital cardiac arrest with either VF or VT and identified those factors associated with delayed defibrillation (>2 minutes). They then examined the association between delayed defibrillation and survival to hospital discharge. Three secondary outcomes were also evaluated: return of spontaneous circulation for at least 20 minutes after the onset of cardiac arrest, survival at 24 hours after the cardiac arrest and neurological and functional status at discharge.

The characteristics associated with delayed defibrillation included black race, non-cardiac admitting diagnosis, occurrence of cardiac arrest in a hospital with <250 beds, being in an unmonitored hospital unit and the arrest occurring during out of hours periods. The overall median defibrillation time was 1 minute (interquartile range <1–3 minutes) with delayed defibrillation occurring in 2045 patients (30.1%). Delayed defibrillation was associated with a significantly lower probability of surviving to hospital discharge (22.2% vs 39.3%, adjusted odds ratio  =  0.48, 95% CI 0.42 to 0.54, p<0.001). A graded association was observed between increasing time to defibrillation and lower rates of survival to hospital discharge for each minute of delay (p for trend <0.001). The study also identified various clinical characteristics associated with an increased risk of VT or VF, including a history of heart disease, respiratory insufficiency, diabetes mellitus and renal dysfunction. Delayed defibrillation remained an important determinant of outcome notwithstanding this.

The findings suggest that rapid defibrillation is associated with important survival gains and also identified a graded association between poorer survival and prolonged time to defibrillation. Several factors related to the hospital setting were associated with delayed defibrillation …