title: Does the choice of definition for defibrillation and CPR success impact the predictability of ventricular fibrillation waveform analysis?
abstract: Quantitative analysis of ventricular fibrillation (VF), such as amplitude spectral area (AMSA), predicts shock outcomes. However, there is no uniform definition of shock/cardiopulmonary resuscitation (CPR) success in out-of-hospital cardiac arrest (OHCA). The objective of this study is to investigate post-shock rhythm variations and the impact of shock/CPR success definition on the predictability of AMSA.
  
  
  
  A total of 554 shocks from 257 OHCA patients with VF as initial rhythm were analyzed. Post-shock rhythms were analyzed every 5s up to 120s and annotated as VF, asystole (AS) and organized rhythm (OR) at serial time intervals. Three shock/CPR success definitions were used to evaluate the predictability of AMSA: (1) termination of VF (ToVF); (2) return of organized electrical activity (ROEA); (3) return of potentially perfusing rhythm (RPPR).
  
  
  
  Rhythm changes occurred after 54.5% (N=302) of shocks and 85.8% (N=259) of them occurred within 60s after shock delivery. The observed post-shock rhythm changes were (1) from AS to VF (24.9%), (2) from OR to VF (16.1%), and (3) from AS to OR (12.1%). The area under the receiver operating characteristic curve (AUC) for AMSA as a predictor of shock/CPR success reached its maximum 60s post-shock. The AUC was 0.646 for ToVF, 0.782 for ROEA, and 0.835 for RPPR (p<0.001) respectively.
  
  
  
  Post-shock rhythm is unstable in the first minute after the shock. The predictability of AMSA varies depending on the definition of shock/CPR success and performs best with the return of potentially perfusing rhythm endpoint for OHCA.
authors.affiliation: School of Biomedical Engineering, Third Military Medical University, Chongqing 400038, China; Information Department, The 303th Hospital of PLA, Nanning, Guangxi 530021, China.
authors.forename: Danian
authors.initials: D
authors.lastname: Jin
authors.affiliation: School of Biomedical Engineering, Third Military Medical University, Chongqing 400038, China.
authors.forename: Chenxi
authors.initials: C
authors.lastname: Dai
authors.affiliation: School of Biomedical Engineering, Third Military Medical University, Chongqing 400038, China.
authors.forename: Yushun
authors.initials: Y
authors.lastname: Gong
authors.affiliation: Emergency Department, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China.
authors.forename: Yubao
authors.initials: Y
authors.lastname: Lu
authors.affiliation: Emergency Department, Southwest Hospital, Third Military Medical University, Chongqing 400038, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Zhang
authors.affiliation: ZOLL Medical Corporation, Chelmsford, MA 01824, USA.
authors.forename: Weilun
authors.initials: W
authors.lastname: Quan
authors.affiliation: School of Biomedical Engineering, Third Military Medical University, Chongqing 400038, China. Electronic address: leeoken@gmail.com.
authors.forename: Yongqin
authors.initials: Y
authors.lastname: Li
mesh_terms: D016887:Cardiopulmonary Resuscitation; D004554:Electric Countershock; D005544:Forecasting; D006801:Humans; D016896:Treatment Outcome; D014693:Ventricular Fibrillation / Q000503:physiopathology* / Q000628:therapy*
keywords: Amplitude spectral area; Cardiac arrest; Definition; Shock/CPR success; Ventricular fibrillation