Uniformity of pulmonary diffusion: effect of lung volume

¹ Department of Medicine, University of Chicago, Chicago, Illinois

In two normal subjects, the effect of changing lung volume on the uniformity of pulmonary diffusion (uniformity of Dl/Vl) was studied using the breath-holding and equilibration methods. Nonuniformity of diffusion, as indicated by deviation from a true exponential in the disappearance of carbon monoxide from alveolar gas, was seen to increase with increasing lung volume. Over-all Dl increased significantly with increasing lung volume. When lung volume was controlled, equilibration and breath-holding diffusion methods yielded similar over-all Dl and similar variation in Dl/Vl throughout the lung.