AnterioR-Posterior VErsuS Anterior-LaTeral defibrillator pAd position in out of hospital cardiac aRresT

Background

Early defibrillation is a key factor of survival following out-of-hospital cardiac arrest (OHCA). In the United Kingdom, initial anterior–lateral (AL) defibrillator pad placement is standard practice. However, anterior–posterior (AP) pad positioning has been proposed as a method of improving current flow through the myocardium particularly in cases of refractory ventricular fibrillation (VF). Concerns remain regarding potential delays to defibrillation associated with alternative pad placement strategies and the practical application of AP positioning.

Objective

We conducted two consecutive simulation studies to explore whether there is a difference in the time taken to apply defibrillator pads, and placement accuracy, between AP and AL positions during simulated OHCA.

Methods

This research study comprised of two simulation studies. First, we evaluated pad placement accuracy before and after written instruction showing optimal pad placement (RESTART-SIM accuracy). Second, we undertook a randomised crossover examining time to pad placement, timing to successful pad application was recorded for each attempt (RESTART-SIM speed).

Results

RESTART-SIM (accuracy) out of 14 participants 50% correctly placed AL pads and 14% correctly placed AP pads initially. Following provision of guidance this increased to 93% for AL but remained at 14% for AP placement.

9 participants completed RESTART-SIM (speed). Mean AP pad placement time was 14.2 seconds and standard deviation of 2.64, compared with 10.6 seconds for AL placement and a standard deviation of 4.24. AP first strategy mean placement time was 15.3 seconds and mean AL placement time was 11.5 seconds. In AL first mean AP placement time was 12.8 seconds and mean AL placement time was 9.6 seconds.

Conclusion

AP pad placement whilst slower than AL placement the time difference of 4 seconds is unlikely to be clinically significant. However, without guidance, both AL and AP placements were often inaccurate. After a guidance picture AL placement was increased but AP remained poorly placed.