title: Amplitude spectral area: predicting the success of electric shock delivered by defibrillators with different waveforms.
abstract: OBJECTIVE
  Prolonged ventricular fibrillation (VF) is associated with a low rate of return of spontaneous circulation (ROSC) following electric shock. Moreover, electric shock that does not reestablish spontaneous circulation causes myocardial dysfunction even if ROSC is subsequently achieved. Amplitude spectral area (AMSA), calculated by analysis of VF waveforms immediately before electric shock, is considered to predict the outcome of electric shock. This study aimed to evaluate the prognostic value of AMSA in relation to waveforms of defibrillators in prehospital settings.
  
  
  METHODS
  The AMSA values of 81 patients with VF confirmed by ambulance crews were compared according to the type of defibrillators with different waveforms and between those with and without ROSC.
  
  
  RESULTS
  With a biphasic defibrillator, the mean AMSA was significantly different between the 14 patients who achieved ROSC (25.3 ± 9.5 mV-Hz) and the 43 subjects who did not achieve ROSC (15.4 ± 8.1 mV-Hz; p = 0.0006). No significant difference was seen in the corresponding values when a monophasic defibrillator was used, at 19.1 ± 2.4 mV-Hz for 3 ROSC patients and 16.1 ± 7.5mV-Hz for 21 non-ROSC patients.
  
  
  CONCLUSIONS
  AMSA may serve as a predictive measure for ROSC following electric shock delivered by a biphasic defibrillator.
authors.affiliation: Department of Emergency and Critical Care Medicine, Tokai University School of Medicine, 143 Shimokasuya, Isehara, Kanagawa 259-1193, Japan. yoshihide@is.icc.u-tokai.ac.jp
authors.forename: Yoshihide
authors.initials: Y
authors.lastname: Nakagawa
authors.forename: Yoji
authors.initials: Y
authors.lastname: Sato
authors.forename: Takeshi
authors.initials: T
authors.lastname: Kojima
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Wakabayashi
authors.forename: Seiji
authors.initials: S
authors.lastname: Morita
authors.forename: Mari
authors.initials: M
authors.lastname: Amino
authors.forename: Sadaki
authors.initials: S
authors.lastname: Inokuchi
mesh_terms: D002138:Calibration; D047548:Defibrillators; D004554:Electric Countershock / Q000379:methods*; D005544:Forecasting; D006334:Heart Function Tests / Q000379:methods*; D006801:Humans; D058687:Out-of-Hospital Cardiac Arrest / Q000150:complications* / Q000628:therapy*; D016896:Treatment Outcome; D014693:Ventricular Fibrillation / Q000150:complications* / Q000503:physiopathology*