Blood Volume Adjustments to Shock in Dogs

After experimental hemorrhage in the dog, extravascular fluid enters the vascular compartment and effective circulation in an attempt to minimize the decrease in effective blood volume.1,2As a result, the effective blood volume is not reduced to the extent anticipated. Other studies in experimental hemorrhagic or endotoxic shock in the dog show that trapping of both plasma and erythrocytes3,4or plasma alone occurs.5,6Thus factors which tend to increase and diminish effective blood volume are operative. This study is an attempt to demonstrate the net result of these factors in the shocked dog by comparing the effective blood volume with that anticipated. Method Hemorrhagic Shock. —Fifteen healthy dogs were subjected to hemorrhagic shock by the technique of Hardaway7which avoided systemic heparinization of the animals. Subcutaneous morphine sulfate (1 mg. per pound) was used as premedication, and femoral artery cutdowns were performed under 1% procaine anesthesia.