[Effects of automated external defibrillators on hands-off intervals in lay rescuers]

Survival chances after out-of-hospital cardiac arrests caused by hyperdynamic electric cardiac rhythms can be significantly improved by early defibrillation with automated external defibrillators (AEDs). As postulated in international guidelines, the resulting hands-off intervals should not exceed 10 s.

We investigated delay in onset of chest compressions and the length of hands-off intervals during defibrillation associated with the application of AEDs.

In a prospective, randomized, single-blinded observational study, the resuscitation efforts by first year medical students were analyzed in different emergency scenarios on manikins. Delay in onset of chest compressions and the length of hands-off intervals between voice prompts from four conventional devices were compared during shockable and nonshockable rhythms. Satisfaction with the device, difficulties with the application, and suggested improvements were assessed by questionnaire.

In a total of 70 applications, the start with thoracic compressions was delayed by a mean of 115 s. On average, the first shock was administered after 125 s in shockable heart rhythms. Perishock pauses of less than 10 s were achieved with none of the tested devices. Hands-off intervals during defibrillation differed significantly between the devices (p < 0.001). Improvements were suggested regarding marking, voice prompts, and electrodes.

Perishock pause of less than 10 s was not achieved with any of the tested devices. Shortened and more precise voice prompts as well as more clearly arranged labeling and layout of pads are needed to simplify application, reduce delayed onset of chest compressions and shorten hands-off intervals.