A Comparative Study of Lung Compliance and Pulmonary Surfactant Activity in Human Subjects

Abstract

Twenty-seven patients were studied by measuring dynamic lung compliance and lung extract surface activity to investigate a theoretical correlation. Fifteen patients were without respiratory symptoms or diffuse pulmonary disease. They were classified Group I (9 patients) with normal ventilation, normal lung compliance, and normal pulmonary surfactant activity, or Group II (6 patients) with either obstructed or restricted ventilation, low lung compliance (2 of 6 patients), and normal pulmonary surfactant activity. The other 12 patients, who made up Group III, were studied because they had radiographically apparent diffuse pulmonary disease. Their ventilatory impairment was consistent with the histopathology; however, lung compliance was normal in all but 1 patient, whereas pulmonary surfactant activity was abnormal in 4 including the patient with low compliance. It is concluded that (1) dynamic lung compliance may be independently abnormal in patients with obstructive ventilation; (2) pulmonary surfactant activity may be independently abnormal in lungs with parenchymal pathology; and (3) the I case of dynamic lung compliance and pulmonary surfactant found in this investigation does not constitute sufficient evidence to establish a correlation between these entities.