A comparison of two automated external defibrillator algorithms

To compare the interval to delivery of the first shock by first responders in mannequin-based cardiac arrest scenarios using two automated external defibrillator (AED) algorithms.

Thirty-six (18 pairs) of Toronto firefighters (FFs) trained in two AED algorithms, algorithm I (A-I) and algorithm II (A-II), were studied. A-II mandates the immediate application of the AED once pulselessness is established. In contrast to A-I, A-II dictates that no CPR be initiated until it is required by the AED voice prompts. Each FF pair alternated roles while performing "shock-indicated," mannequin-based scenarios according to A-I and A-II. The interval from mannequin contact to delivery of the first shock was recorded. Five pairs were videotaped. The intervals to complete predetermined steps were compared between algorithms to determine in which step(s) time saving occurred.

The mean (+/-SD) interval to the first shock in A-I was 80.7 seconds (+/-10.5 sec) (95% CI = 77.2 to 84.2 sec) vs 61.1 seconds (+/-8.75 sec) (95% CI = 58.2 to 64.0 sec) in A-II (p < 0.001). A-II shortened the interval to the first shock by 19.6 sec (+/-11.5) (95% CI = 15.8 to 23.4 sec). The time saving was a direct result of delaying CPR in A-II.

A-II reduced the interval from mannequin contact to the first shock in standard training scenarios.