title: The quality of chest compressions during cardiopulmonary resuscitation overrides importance of timing of defibrillation.
abstract: BACKGROUND
  We address the quality of chest compressions and the impact on initial defibrillation or initial chest compressions after sudden death.
  
  
  METHODS
  Ventricular fibrillation was induced by occlusion of the left anterior descending coronary artery in 24 domestic pigs with a mean (+/- SD) weight of 40 +/- 2 kg. Cardiac arrest was left untreated for 5 min. Animals were then randomized to receive chest compressions-first or defibrillation-first and were further randomized to "optimal" or "conventional" chest compressions. A total of four groups of animals were investigated using a factorial design. For optimal chest compressions, the anterior posterior diameter of the chest was reduced by 25%, representing approximately 6 cm. Only 70% of this depth, or approximately 4.2 cm, represented conventional chest compressions. Chest compressions were delivered with a mechanical chest compressor. Defibrillation was attempted with a single biphasic 150-J shock. Postresuscitation myocardial function was echocardiographically assessed.
  
  
  RESULTS
  Coronary perfusion pressures and end-tidal Pco(2) were significantly lower with conventional chest compressions. With optimal chest compressions, either as an initial intervention or after defibrillation, each animal was successfully resuscitated. Fewer shocks were required prior to the return of spontaneous circulation after initial optimal chest compressions. No animals were resuscitated when conventional chest compressions preceded the defibrillation attempt. When defibrillation was attempted as the initial intervention followed by conventional chest compressions, two of six animals were resuscitated.
  
  
  CONCLUSIONS
  In this animal model of cardiac arrest, it was the quality of the chest compressions, rather then the priority of either initial defibrillation or initial chest compressions, that was the predominant determinant of successful resuscitation.
authors.affiliation: Weil Institute of Critical Care Medicine, 35100 Bob Hope Dr, Rancho Mirage, CA 92270, USA.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Ristagno
authors.forename: Wanchun
authors.initials: W
authors.lastname: Tang
authors.forename: Yun-Te
authors.initials: YT
authors.lastname: Chang
authors.forename: Dawn B
authors.initials: DB
authors.lastname: Jorgenson
authors.forename: James K
authors.initials: JK
authors.lastname: Russell
authors.forename: Lei
authors.initials: L
authors.lastname: Huang
authors.forename: Tong
authors.initials: T
authors.lastname: Wang
authors.forename: Shijie
authors.initials: S
authors.lastname: Sun
authors.forename: Max Harry
authors.initials: MH
authors.lastname: Weil
mesh_terms: D000818:Animals; D016887:Cardiopulmonary Resuscitation / Q000379:methods*; D016757:Death, Sudden, Cardiac; D004554:Electric Countershock / Q000379:methods*; D008297:Male; D023421:Models, Animal; D015425:Myocardial Reperfusion; D011897:Random Allocation; D034421:Sus scrofa; D013997:Time Factors; D016896:Treatment Outcome; D014693:Ventricular Fibrillation / Q000628:therapy*