Pulmonary Blood Volume of the Dog and Its Changes in Acute Heart Failure

The volume of blood in the lungs and left heart and the amount of blood that can shift between the pulmonary circulation and the systemic circulation has been measured in intact dogs by a direct method. The systemic blood was separated from the pulmonary blood by instantaneously constricting the pulmonary artery and ascending aorta with plastic loops placed around these vessles at a previous operation. The volume of the two systems was then determined by a washout technique. In 13 control dogs the average pulmonary and left heart blood volume was 10.3 ml/kg ± 1.9 S.D. or 13% of the total blood volume. When acute right heart failure was produced by gradually constricting the pulmonary artery, the pulmonary and left heart blood volume in 12 dogs was reduced to an average of 5.3 ml/kg ± 1.0 S.D., which represents a 48% decrease below the control value. Acute left heart failure was produced by gradual constriction of the ascending aorta in 13 dogs, and the pulmonary and left heart blood volume increased to 17.5 ml/kg ± 2.8 S.D., representing a 70% increase above the control value.