Clinical Evaluation of Pulmonary Function

Abstract

So-called alveolar-capillary block is due chiefly to uneven ventilation with respect to blood flow. In the early stages, the chest x-ray may be normal. Later, symptoms appear, the chest x-ray is usually abnormal, and lung volumes indicate reduced diffusing surface.

Uneven circulation is observed in pulmonary embolism, anemia, intracardiac shunts and chronic inflammatory lung disease. Symptoms of uneven circulation and tests for determining its presence are discussed. Pulmonary hypertension resulting from hypoxemia may be reversible, whereas that arising from restriction of the vascular bed is not. The two processes usually seem to combine early in chronic lung disease. Therapy is more successful if started during this phase or earlier.