Balderston JR, et al. - Researchers sought to ascertain if immediate pre-defibrillation amplitude is associated with successful defibrillation, return of spontaneous circulation (ROSC) or survival to hospital discharge (SHD) in out of hospital cardiac arrest. As per outcomes, successful defibrillation, ROSC, and SHD are all linked to amplitude of the ventricular fibrillation (VF) waveform at the moment of defibrillation.

Methods

• Analysis of automated external defibrillation recordings of 80 patients with out-of-hospital VF cardiac arrest who received 284 defibrillations was performed.
• The maximum amplitude during 3-second ECG tracings prior to each defibrillation attempt and the amplitude immediately prior to defibrillation were recorded.

Results

• In successful defibrillations, both the amplitude just before defibrillation and the highest amplitude within 3 seconds of defibrillation were significantly higher compared to unsuccessful defibrillations (0.21 vs 0.11 mV, p= <0.0001 and 0.51 vs 0.36 mV, p= <0.0001).
• In defibrillations with ROSC, amplitude immediately before defibrillation and maximal amplitude within 3 seconds of defibrillation were also higher compared to defibrillations without ROSC (0.23 vs 0.12 mV, P < .0001; and 0.52 vs 0.38 mV, P < .0001).
• Immediate pre-defibrillation amplitude and maximum amplitude were also significantly larger in defibrillations that resulted in SHD (0.20 vs 0.11 mV, P < .0001; and 0.52 vs 0.35 mV, P < .0001).
• In this study, binary logistic regression including both measures demonstrated that only immediate pre-defibrillation amplitude remained significantly associated with ROSC while maximal amplitude did not (P=.006 and P=.135).