Automated external defibrillator electrode size and termination of ventricular fibrillation in out-of-hospital cardiac arrest

Rose T. Yin, Tyson G. Taylor, Corina de Graaf, Mette M. Ekkel, Fred W. Chapman, Rudolph W. Koster

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

Smaller electrodes allow more options for design of automated external defibrillator (AED) user interfaces. However, previous studies employing monophasic-waveform defibrillators found that smaller electrode sizes have lower defibrillation shock success rates. We hypothesize that, for impedance-compensated, biphasic truncated exponential (BTE) shocks, smaller electrodes increase transthoracic impedance (TTI) but do not adversely affect defibrillation success rates. Methods and Results: In this prospective before-and-after clinical study, Amsterdam police and firefighters used AEDs with BTE waveforms: an AED with larger electrodes in 2016–2017 (113 cm2), and an AED with smaller electrodes in 2017–2020 (65 cm2). We analyzed 157 and 178 patient cases with an initial shockable rhythm where the larger and smaller electrodes were used, respectively. A single 200-J shock terminated ventricular fibrillation (VF) in 86% of patients treated with large electrodes and 89% of patients treated with smaller electrodes. Small electrodes had a non-inferior first shock defibrillation success rate compared to large electrodes, with a difference of 3% (95% CI: –3% −9%) with the lower confidence limit remaining above the defined non-inferiority threshold. TTI was significantly higher for the smaller electrodes (median: 100 Ω) compared to the larger electrodes (median: 88 Ω) (p < 0.001). Conclusions: For AEDs with impedance-compensating BTE waveforms, TTI was higher for smaller electrodes than the large electrode electrodes. Overall defibrillation shock success for AEDs with smaller electrodes was non-inferior to the AEDs with larger electrodes.

Original languageEnglish
Article number109754
JournalResuscitation
Volume185
DOIs
Publication statusPublished - 1 Apr 2023

Keywords

  • AED
  • Biphasic waveform
  • Defibrillation
  • Electrodes
  • Impedance compensation
  • Out-of-hospital cardiac arrest

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