Abstract 87: Effects of Variable Depth of Chest Compression on Outcomes of CPR
Introduction. Both in- and out-of-hospital chest compressions are typically delivered ineffectively. We therefore evaluated the quality of chest compressions (CC) as recommended in the AHA CPR Guidelines. We hypothesized that the new standards will improve outcomes and that small deviations will decrease resuscitability.
Methods. In 10 domestic male pigs weighing 40 ± 2 kg, ventricular fibrillation was electrically induced and untreated for 5 minutes. Animals were then randomized to receive 3 minutes of CC in compliance with the guidelines, in which the anterior posterior diameter of the chest was reduced by 25% representing approximately 6 cm and compared with 70% of this depth or approximately 4 cm. CC was delivered with the aid of a mechanical chest compressor (Thumper, Model 1000, Michigan Instruments, Grand Rapids, MI) at a rate of 100/min. Transthoracic defibrillation was attempted with a single biphasic 150 Joule shock.
Results. Coronary perfusion pressure (CPP) was significantly lower in the animals in which CC was performed with 70% of the recommended depth (Figure⇓). Each animal in which CC was performed in accord with the guidelines was successfully resuscitated and each animal survived for more than 72 hrs. No animal which had CC after a 30% reduction in depth had return of spontaneous circulation (p<0.001).
Conclusions. In this model, chest compression depth during CPR was a major determinant of outcome.