Studies on lung volume. VIII. Patients with heart disease (mitral lesions)

Abstract

The lung volumes were determined in 11 adult patients with mitral lesions. Three of the patients were in the uncompensated state of the disease. Nine were in the compensated stage. In these last patients the second pulmonary sound was markedly accentuated indicating an increased pressure in the pulmonary circulation. Our technique was as previously described. 1 Care was taken to secure full mixture in determining the total capacity. All the lung volumes are given at room temperature and observed pressure as in previous publications of the series.

Results. Discussion will appear more complete elsewhere 2 , 3 and only the main results will be given here. Relative lung volumes are given in Table I in percentage of the normal relative value for total capacity, middle capacity, residual air, and vital capacity, respectively (100, 62.0, 24.7, and 75.3) established in a previous paper. These values show in all instances a decrease in the vital capacity and an increase in the residual air. The values for the middle capacity vary. These results are in accordance with the results of other investigators.

Calculated normal values and observed values. The normal values for the different lung volumes in each patient are calculated from the size of the chest which was determined according to the procedure of Van Slyke and Lundsgaard. On account of the diminished range of chest movement only the ratio (54/100) for the total lung volume was used. The other lung volumes were calculated by means of the normal ratios for the relative lung volumes (100 — 62 — 24.7 and 75.3) previously published. This mode of calculation was adopted on account of the diminished range of chest movement and because we have every reason to believe that the maximum inspiratory expansion is normal in these cases. However, the lung volumes based on all the normal ratios did usually not differ materially from those reported in Table II. In Table II the directly observed lung volumes are given in percentage of the calculated normal figures. The information gained in this way gives quite another picture than the (so to speak distorted) one we get by using the relative values.