title: Short ECG segments predict defibrillation outcome using quantitative waveform measures.
abstract: Quantitative waveform measures of the ventricular fibrillation (VF) electrocardiogram (ECG) predict defibrillation outcome. Calculation requires an ECG epoch without chest compression artifact. However, pauses in CPR can adversely affect survival. Thus the potential use of waveform measures is limited by the need to pause CPR. We sought to characterize the relationship between the length of the CPR-free epoch and the ability to predict outcome.
  
  
  
  We conducted a retrospective investigation using the CPR-free ECG prior to first shock among out-of-hospital VF cardiac arrest patients in a large metropolitan region (n=442). Amplitude Spectrum Area (AMSA) and Median Slope (MS) were calculated using ECG epochs ranging from 5s to 0.2s. The relative ability of the measures to predict return of organized rhythm (ROR) and neurologically-intact survival was evaluated at different epoch lengths by calculating the area under the receiver operating characteristic curve (AUC) using the 5-s epoch as the referent group.
  
  
  
  Compared to the 5-s epoch, AMSA performance declined significantly only after reducing epoch length to 0.2s for ROR (AUC 0.77-0.74, p=0.03) and with epochs of ≤0.6s for neurologically-intact survival (AUC 0.72-0.70, p=0.04). MS performance declined significantly with epochs of ≤0.8s for ROR (AUC 0.78-0.77, p=0.04) and with epochs ≤1.6s for neurologically-intact survival (AUC 0.72-0.71, p=0.04).
  
  
  
  Waveform measures predict defibrillation outcome using very brief ECG epochs, a quality that may enable their use in current resuscitation algorithms designed to limit CPR interruption.
authors.affiliation: Department of Bioengineering, University of Washington, Seattle, WA, USA; Center for Progress in Resuscitation, University of Washington, Seattle, WA, USA. Electronic address: jasonc4@uw.edu.
authors.forename: Jason
authors.initials: J
authors.lastname: Coult
authors.affiliation: Department of Bioengineering, University of Washington, Seattle, WA, USA; Center for Progress in Resuscitation, University of Washington, Seattle, WA, USA; Department of Medicine, University of Washington School of Medicine, Seattle, WA, USA.
authors.forename: Lawrence
authors.initials: L
authors.lastname: Sherman
authors.affiliation: Center for Progress in Resuscitation, University of Washington, Seattle, WA, USA; Department of Medicine, University of Washington School of Medicine, Seattle, WA, USA.
authors.forename: Heemun
authors.initials: H
authors.lastname: Kwok
authors.affiliation: Center for Progress in Resuscitation, University of Washington, Seattle, WA, USA; King County Emergency Medical Services, Seattle King County Department of Public Health, Seattle, WA, USA.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Blackwood
authors.affiliation: Center for Progress in Resuscitation, University of Washington, Seattle, WA, USA; King County Emergency Medical Services, Seattle King County Department of Public Health, Seattle, WA, USA; Department of Medicine, University of Washington School of Medicine, Seattle, WA, USA; Division of Cardiology, University of Washington School of Medicine, Seattle, WA, USA.
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Kudenchuk
authors.affiliation: Center for Progress in Resuscitation, University of Washington, Seattle, WA, USA; King County Emergency Medical Services, Seattle King County Department of Public Health, Seattle, WA, USA; Department of Medicine, University of Washington School of Medicine, Seattle, WA, USA.
authors.forename: Thomas D
authors.initials: TD
authors.lastname: Rea
mesh_terms: D000368:Aged; D016887:Cardiopulmonary Resuscitation / Q000379:methods* / Q000401:mortality; D004554:Electric Countershock / Q000379:methods* / Q000401:mortality; D004562:Electrocardiography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D058687:Out-of-Hospital Cardiac Arrest / Q000401:mortality / Q000628:therapy*; D012372:ROC Curve; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D016019:Survival Analysis; D013997:Time Factors; D016896:Treatment Outcome; D014693:Ventricular Fibrillation / Q000401:mortality / Q000503:physiopathology / Q000628:therapy*
keywords: Amplitude spectrum area; Automated external defibrillator; Defibrillation; Electrocardiogram; Quantitative waveform measures; Ventricular fibrillation