title: Analysis of the ventricular fibrillation ECG signal amplitude and frequency parameters as predictors of countershock success in humans.
abstract: OBJECTIVE
  The purpose of this study was to assess from the ventricular fibrillation ECG signal whether certain amplitude parameters, or frequency parameters derived using fast Fourier transform analysis, are predictive of countershock success (defined as a stable supraventricular rhythm following countershock).
  
  
  METHODS
  Retrospective, descriptive study.
  
  
  METHODS
  Emergency medical service at a university hospital.
  
  
  METHODS
  Twenty-six patients with out-of-hospital cardiac arrest, whose initial ECG rhythm was identified as ventricular fibrillation.
  
  
  RESULTS
  In all patients, advanced cardiac life support was performed in the out-of-hospital setting and a semiautomatic defibrillator was used for countershock therapy and simultaneous on-line ECG recording. For each patient, ECG data were stored in modules in digitized form over a period of 20 min and analyzed retrospectively. Using fast Fourier transform analysis of the ventricular fibrillation ECG signal in the frequency range of 0.3 to 30 Hz (mean +/- SD), median frequency, dominant frequency, edge frequency, and amplitude were as follows: 5.17 +/- 1.05 Hz, 4.56 +/- 0.99 Hz, 10.74 +/- 3.46 Hz, and 1.33 +/- 0.44 mV before successful countershock (n = 20); and 4.21 +/- 1.17 Hz (p = 0.0034), 3.31 +/- 1.57 Hz (p = 0.0004), 9.46 +/- 2.93 Hz (p = 0.5390), and 1.15 +/- 0.69 mV (p = 0.0134) before unsuccessful countershock (n = 134). Using software filters to completely eliminate interference due to manual cardiopulmonary resuscitation from the ventricular fibrillation power spectrum, only amplitude remained statistically different (p < or = 0.03) in predicting countershock success.
  
  
  CONCLUSIONS
  We conclude that in patients, median frequency, dominant frequency, and amplitude are predictive of countershock success in humans.
authors.affiliation: Department of Anesthesiology and Critical Care Medicine, University of Ulm, Germany.
authors.forename: H U
authors.initials: HU
authors.lastname: Strohmenger
authors.forename: K H
authors.initials: KH
authors.lastname: Lindner
authors.forename: C G
authors.initials: CG
authors.lastname: Brown
mesh_terms: D004554:Electric Countershock; D004562:Electrocardiography; D005583:Fourier Analysis; D006323:Heart Arrest / Q000503:physiopathology / Q000628:therapy; D006801:Humans; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D016896:Treatment Outcome; D014693:Ventricular Fibrillation / Q000175:diagnosis* / Q000628:therapy