Pulmonary Function in Diaphragmatic Paralysis

Abstract

Three patients with diaphragmatic paralysis are reported, and results of pulmonary function tests are presented. Impairment of diaphragmatic function produces a pattern of pulmonary dysfunction characterized by diminution in vital capacity in the erect posture and, if dyspnoe is present, the difficulty is chiefly with inspiration. Orthopnoea is the outstanding symptom in these patients. In the recumbent position vital capacity is still further reduced, and there may be a fall in arterial oxygen saturation. Orthopnoea is caused by elevation of the diaphragm in the supine position, which leads to decrease in lung volume and increased stiffness of the lungs, together with the mechanical inefficiency of the diaphragm as a muscle of inspiration against the increased pressure of abdominal contents in this position. Anoxaemia may be a contributory factor, and alveolar hypoventilation and hypercapnoea did not occur. (XV, 19).