title: Association of amplitude spectral area of the ventricular fibrillation waveform with survival of out-of-hospital ventricular fibrillation cardiac arrest.
abstract: BACKGROUND
  Previous investigations of out-of-hospital cardiac arrest (OHCA) have shown that the waveform characteristic amplitude spectral area (AMSA) can predict successful defibrillation and return of spontaneous circulation (ROSC) but has not been studied previously for survival.
  
  
  OBJECTIVE
  To determine whether AMSA computed from the ventricular fibrillation (VF) waveform is associated with pre-hospital ROSC, hospital admission, and hospital discharge.
  
  
  METHODS
  Adults with witnessed OHCA and an initial rhythm of VF from an Utstein style database were studied. AMSA was measured prior to each shock and averaged for each subject (AMSA-avg). Factors such as age, sex, number of shocks, time from dispatch to monitor/defibrillator application, first shock AMSA, and AMSA-avg that could predict pre-hospital ROSC, hospital admission, and hospital discharge were analyzed by logistic regression.
  
  
  RESULTS
  Eighty-nine subjects (mean age 62 ± 15 years) with a total of 286 shocks were analyzed. AMSA-avg was associated with pre-hospital ROSC (p = 0.003); a threshold of 20.9 mV-Hz had a 95% sensitivity and a 43.4% specificity. Additionally, AMSA-avg was associated with hospital admission (p < 0.001); a threshold of 21 mV-Hz had a 95% sensitivity and a 54% specificity and with hospital discharge (p < 0.001); a threshold of 25.6 mV-Hz had a 95% sensitivity and a 53% specificity. First-shock AMSA was also predictive of pre-hospital ROSC, hospital admission, and discharge. Time from dispatch to monitor/defibrillator application was associated with hospital admission (p = 0.034) but not pre-hospital ROSC or hospital discharge.
  
  
  CONCLUSIONS
  AMSA is highly associated with pre-hospital ROSC, survival to hospital admission, and hospital discharge in witnessed VF OHCA. Future studies are needed to determine whether AMSA computed during resuscitation can identify patients for whom continuing current resuscitation efforts would likely be futile.
authors.affiliation: Sarver Heart Center, University of Arizona College of Medicine, Tucson, Arizona. Electronic address: jindik@email.arizona.edu.
authors.forename: Julia H
authors.initials: JH
authors.lastname: Indik
authors.affiliation: Sarver Heart Center, University of Arizona College of Medicine, Tucson, Arizona.
authors.forename: Zacherie
authors.initials: Z
authors.lastname: Conover
authors.affiliation: Sarver Heart Center, University of Arizona College of Medicine, Tucson, Arizona.
authors.forename: Meghan
authors.initials: M
authors.lastname: McGovern
authors.affiliation: ZOLL Medical, Chelmsford, Massachusetts.
authors.forename: Annemarie E
authors.initials: AE
authors.lastname: Silver
authors.affiliation: Department of Emergency Medicine, University of Arizona College of Medicine, Tucson, Arizona.
authors.forename: Daniel W
authors.initials: DW
authors.lastname: Spaite
authors.affiliation: Department of Emergency Medicine, Maricopa Medical Center, University of Arizona College of Medicine, Phoenix, Arizona.
authors.forename: Bentley J
authors.initials: BJ
authors.lastname: Bobrow
authors.affiliation: Sarver Heart Center, University of Arizona College of Medicine, Tucson, Arizona.
authors.forename: Karl B
authors.initials: KB
authors.lastname: Kern
mesh_terms: D000328:Adult; D000368:Aged; D019540:Area Under Curve; D001130:Arizona; D016887:Cardiopulmonary Resuscitation; D016208:Databases, Factual; D047548:Defibrillators; D004554:Electric Countershock; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D058687:Out-of-Hospital Cardiac Arrest / Q000503:physiopathology*; D010343:Patient Admission; D010351:Patient Discharge; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D014693:Ventricular Fibrillation / Q000503:physiopathology*
keywords: cardiopulmonary resuscitation; heart arrest; ventricular fibrillation