Hemoconcentration during cardiac arrest and CPR

The objective of this study was to determine if hemoconcentration occurs during cardiac arrest and cardiopulmonary resuscitation (CPR). The design was an animal model of cardiac arrest and CPR performed at a research institute using six mongrel dogs. After the induction of cardiac arrest, animals were subjected to 4 minutes of ventricular fibrillation followed by 20 minutes of CPR. Resuscitation was then achieved using countershocks, drugs, and intravenous fluids. Hemoglobin concentrations were obtained before arrest and every 5 minutes during CPR. An average peak increase in hemoglobin concentration of 21% was observed during CPR. Hemoconcentration occurs during cardiac arrest and CPR, and this may be a result of a shift in volume from the intravascular to the extravascular space.