title: Minimal interruption of cardiopulmonary resuscitation for a single shock as mandated by automated external defibrillations does not compromise outcomes in a porcine model of cardiac arrest and resuscitation.
abstract: OBJECTIVE
  Current automated external defibrillations require interruptions in chest compressions to avoid artifacts during electrocardiographic analyses and to minimize the risk of accidental delivery of an electric shock to the rescuer. The earlier three-shock algorithm, with prolonged interruptions of chest compressions, compromised outcomes and increased severity of postresuscitation myocardial dysfunction. In the present study, we investigated the effect of timing of minimal automated external defibrillation-mandated interruptions of chest compressions on cardiopulmonary resuscitation outcomes, using a single-shock algorithm. We hypothesized that an 8-sec interruption of chest compressions for a single shock, as mandated by automated external defibrillations, would not impair initial resuscitation and outcomes of cardiopulmonary resuscitation.
  
  
  METHODS
  Randomized prospective animal study.
  
  
  METHODS
  University affiliated research laboratory.
  
  
  METHODS
  Domestic pigs.
  
  
  RESULTS
  In 24 domestic male pigs weighing 41 +/- 2 kg, ventricular fibrillation was induced by left anterior descending coronary artery occlusion and untreated for 7 min. Cardiopulmonary resuscitation, including chest compressions and ventilation with oxygen, was then performed for an interval of 2 min before attempted defibrillation. Animals were randomized into three groups: A) interruption immediately before defibrillation; B) interruption after 1 min of cardiopulmonary resuscitation; or C) no interruption. Chest compressions were delivered with the aid of a mechanical chest compressor at a rate of 100 compressions/min and compression/ventilation ratio of 30:2. Defibrillation was attempted with a single biphasic 150-J shock. Each animal was successfully resuscitated and survived for >72 hr. No differences in the number of shocks before return of spontaneous circulation, frequency of recurrent ventricular fibrillation, duration of cardiopulmonary resuscitation, and severity of postresuscitation myocardial dysfunction were observed.
  
  
  CONCLUSIONS
  In this experimental model of cardiac arrest and cardiopulmonary resuscitation, minimal automated external defibrillation-mandated interruption of chest compressions for a single-shock algorithm did not have adverse effects on postresuscitation myocardial or neurologic function. All animals, whether subjected to cardiopulmonary resuscitation interruptions or not, survived.
authors.affiliation: Weil Institute of Critical Care Medicine, Rancho Mirage, CA, USA.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Ristagno
authors.forename: Wanchun
authors.initials: W
authors.lastname: Tang
authors.forename: James K
authors.initials: JK
authors.lastname: Russell
authors.forename: Dawn
authors.initials: D
authors.lastname: Jorgenson
authors.forename: Hao
authors.initials: H
authors.lastname: Wang
authors.forename: Shijie
authors.initials: S
authors.lastname: Sun
authors.forename: Max Harry
authors.initials: MH
authors.lastname: Weil
mesh_terms: D000465:Algorithms; D000818:Animals; D016887:Cardiopulmonary Resuscitation / Q000379:methods*; D004554:Electric Countershock / Q000379:methods*; D006321:Heart / Q000503:physiopathology; D006323:Heart Arrest / Q000503:physiopathology / Q000628:therapy*; D006336:Heart Massage / Q000379:methods*; D008297:Male; D011446:Prospective Studies; D013552:Swine; D014693:Ventricular Fibrillation / Q000628:therapy