The quality of chest compressions during cardiopulmonary resuscitation overrides importance of timing of defibrillation.
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.
Ristagno
Giuseppe
G
Weil Institute of Critical Care Medicine, 35100 Bob Hope Dr, Rancho Mirage, CA 92270, USA.
Tang
Wanchun
W
Chang
Yun-Te
YT
Jorgenson
Dawn B
DB
Russell
James K
JK
Huang
Lei
L
Wang
Tong
T
Sun
Shijie
S
Weil
Max Harry
MH
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*