A state of deficiency of oxygen in the blood, or anoxemia, may be produced by diminishing the concentration of oxygen in the air breathed, or, as is usual in clinical disease, through an impairment of the functional activity of the respiratory or circulatory system. An adequate transportation of oxygen from the lungs to the tissues is maintained by the normal heart. In cardiac disease an impairment of this function exists, although the significance of this type of anoxemia in the symptomatology of cardiac failure is not clearly understood.
Various aspects of the factor of the deficiency of oxygen in the blood in the production of the symptoms of cardiac failure have been under investigation for the past two decades. In 1915, Means and Newburgh1 found a diminished oxygen saturation in the venous blood in cases of cardiac insufficiency. Their results were confirmed in a larger number of