Studies on the intrapulmonary mixture of gases. III. An open circuit method for measuring residual air

In preceding papers of this series, we have studied (1) the relative effectiveness of mixing or distribution of tidal air into alveolar spaces in normal and abnormal subjects, and have pro-posed (2) an open circuit method for residual air determination, in which nitrogen in the lungs is washed out by continuous inhalation of pure oxy-gen. The present paper (a) gives the results of a number of determinations of residual air, by the open circuit method, in normal subjects and pa-tients with chronic cardiac or chronic pulmonary disease; (b) offers certain simplifications of tech-nique in the open circuit method; and (c) sug-gests further significance of some of the dat