Pulmonary Function in Infiltrative Lung Disease

¹ Chief, Pulmonary Function Laboratory, Veterans Administration Hospital, and Assistant Professor of Medicine, Baylor College of Medicine
² Chief, Radiology Service, Veterans Administration Hospital, and Associate Professor of Radiology, Baylor College of Medicine

Total lung capacity (TLC), vital capacity (VC), diffusing capacity (DL) and deflation pressure volume curves of the lung (PST) were measured in 33 patients with roentgenographic evidence of infiltrative lung disease. The decrease in TLC was a result of decrease in VC in all but three patients. When lung volume was reduced, PST was increased and when lung volume was normal, PST was also normal. Of 17 patients with normal TLC and PST, DL was reduced in 7 and normal in 10. Of 14 patients with reduced TLC and increased PST, DL was normal in 4 and reduced in 10. In this study, PST measurement did not contribute to quantitating lung disease independent of lung volume. DL measurements may be abnormal in the presence of normal lung volume. All these tests may be within normal range in the presence of extensive infiltrative disease on chest roentgenogram.