title: Prediction of successful defibrillation in human victims of out-of-hospital cardiac arrest: a retrospective electrocardiographic analysis.
abstract: In the present study we sought to examine the efficacy of an electrocardiographic parameter, 'amplitude spectrum area' (AMSA), to predict the likelihood that any one electrical shock would restore a perfusing rhythm during cardiopulmonary resuscitation in human victims of out-of-hospital cardiac arrest. AMSA analysis is not invalidated by artefacts produced by chest compression and thus it can be performed during CPR, avoiding detrimental interruptions of chest compression and ventilation. We hypothesised that a threshold value of AMSA could be identified as an indicator of successful defibrillation in human victims of cardiac arrest. Analysis was performed on a database of electrocardiographic records, representing lead 2 equivalent recordings from automated external defibrillators including 210 defibrillation attempts from 90 victims of out-of-hospital cardiac arrest. A 4.1 second interval of ventricular fibrillation or ventricular tachycardia, recorded immediately preceding the delivery of the shock, was analysed using the AMSA algorithm. AMSA represents a numerical value based on the sum of the magnitude of the weighted frequency spectrum between two and 48 Hz. AMSA values were significantly greater in successful defibrillation (restoration of a perfusing rhythm), compared to unsuccessful defibrillation (P < 0.0001). An AMSA value of 12 mV-Hz was able to predict the success of each defibrillation attempt with a sensitivity of 0.91 and a specificity of 0.97. In conclusion, AMSA analysis represents a clinically applicable method, which provides a real-time prediction of the success of defibrillation attempts. AMSA may minimise the delivery of futile and detrimental electrical shocks, reducing thereby post-resuscitation myocardial injury.
authors.affiliation: Weil Institute of Critical Care Medicine, Rancho Mirage, California, USA.
authors.forename: G
authors.initials: G
authors.lastname: Ristagno
authors.forename: A
authors.initials: A
authors.lastname: Gullo
authors.forename: G
authors.initials: G
authors.lastname: Berlot
authors.forename: U
authors.initials: U
authors.lastname: Lucangelo
authors.forename: E
authors.initials: E
authors.lastname: Geheb
authors.forename: J
authors.initials: J
authors.lastname: Bisera
mesh_terms: D000465:Algorithms; D016887:Cardiopulmonary Resuscitation / Q000379:methods / Q000706:statistics & numerical data; D004554:Electric Countershock / Q000379:methods / Q000706:statistics & numerical data*; D004562:Electrocardiography / Q000379:methods / Q000706:statistics & numerical data*; D006323:Heart Arrest / Q000628:therapy*; D006801:Humans; D015588:Observer Variation; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D017180:Tachycardia, Ventricular / Q000628:therapy; D013997:Time Factors; D016896:Treatment Outcome; D014693:Ventricular Fibrillation / Q000628:therapy