Automated external defibrillators and survival after in-hospital cardiac arrest.

CONTEXT: Automated external defibrillators (AEDs) improve survival from out-of-hospital cardiac arrests, but data on their effectiveness in hospitalized patients are limited.

OBJECTIVE: To evaluate the association between AED use and survival for in-hospital cardiac arrest.

DESIGN, SETTING, AND PATIENTS: Cohort study of 11,695 hospitalized patients with cardiac arrests between January 1, 2000, and August 26, 2008, at 204 US hospitals following the introduction of AEDs on general hospital wards.

MAIN OUTCOME MEASURE: Survival to hospital discharge by AED use, using multivariable hierarchical regression analyses to adjust for patient factors and hospital site.

RESULTS: Of 11,695 patients, 9616 (82.2%) had nonshockable rhythms (asystole and pulseless electrical activity) and 2079 (17.8%) had shockable rhythms (ventricular fibrillation and pulseless ventricular tachycardia). AEDs were used in 4515 patients (38.6%). Overall, 2117 patients (18.1%) survived to hospital discharge. Within the entire study population, AED use was associated with a lower rate of survival after in-hospital cardiac arrest compared with no AED use (16.3% vs 19.3%; adjusted rate ratio [RR], 0.85; 95% confidence interval [CI], 0.78-0.92; P < .001). Among cardiac arrests due to nonshockable rhythms, AED use was associated with lower survival (10.4% vs 15.4%; adjusted RR, 0.74; 95% CI, 0.65-0.83; P < .001). In contrast, for cardiac arrests due to shockable rhythms, AED use was not associated with survival (38.4% vs 39.8%; adjusted RR, 1.00; 95% CI, 0.88-1.13; P = .99). These patterns were consistently observed in both monitored and nonmonitored hospital units where AEDs were used, after matching patients to the individual units in each hospital where the cardiac arrest occurred, and with a propensity score analysis.

CONCLUSION: Among hospitalized patients with cardiac arrest, use of AEDs was not associated with improved survival.