Manual Defibrillators Outperform AEDs in Animal Study

A study that compared automated external defibrillation (AED) with manual defibrillation in a swine model to treat prolonged out-of-hospital ventricular fibrillation found that the AED's longer interval to first compression resulted in a poorer outcome. The study was published in the October 2003 issue of the Annals of Emergency Medicine.

The objective of the study was to determine whether the delays in chest compressions and defibrillation associated with an AED would adversely affect outcome when compared with manual defibrillation. After eight minutes of untreated ventricular fibrillation, 16 swine were randomly assigned to AED defibrillation or manual defibrillation with the same biphasic truncated exponential waveform 150-J shock through the same type of pads. The primary outcome measure was 24-hour survival with good neurologic outcome. Although none of the animals in the AED group survived 24 hours, five of the eight animals in the manual defibrillation group survived 24 hours, all with good neurologic outcome.

The time interval from simulated defibrillator arrival to first compressions was 98 (plus or minus 18) seconds in the AED group versus 68 (plus or minus 15) seconds in the manual group. In particular, the interval from first shock to first chest compressions was 46 (plus or minus 18) seconds versus 22 (plus or minus 16) seconds, respectively. Thus, the mean percentage of time that chest compressions were performed in the first minute after the first countershock was 15% (plus or minus 13%) versus 40% (plus or minus 15%), respectively. The return of spontaneous circulation within five minutes of simulated defibrillator arrival occurred in only one of eight animals in the AED group versus six of eight animals in the manual group. The study was conducted by researchers at the University of Arizona (Tucson, USA), led by Robert A. Berg, M.D., department of pediatrics.




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