Studies on Lung Volume 



163 



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 



54 



the diminished range of chest movement only the ratio ( ^ ) 



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 dimin- 

 ished range of chest movement and because we have every rea- 

 son to believe that the maximum inspiratory expansion is nor- 

 mal in these cases. However, the lung volumes based on all the 

 normal ratios did usually not differ materially from those re- 

 ported in Table II. In Table II the directly observed lung volumes 

 are given in percentage of the calculated normal figures. The in- 

 formation gained in this way gives quite another picture than the 

 (so to speak distorted) one we get by using the relative values. 

 The total capacity is either normal (mild cases) or decreased 

 (more advanced cases). The middle capacity follows as a 

 whole the total capacity. The residual air is decreased in pa- 

 tients in the decompensated stage, but increased in the com- 

 pensated. The vital capacity is in all instances decreased but 

 through a different mechanism in the two types. This observa- 

 tion makes us understand the mechanism of the lung involvment 

 in stasis. In the mild cases an emphysematic condition takes 

 place, probably on account of stiffness of the pulmonary vessels 

 through increased blood pressure in the lungs. (Cf. v. Basch's 

 experiments.) In the advanced cases some of the space for the 

 residual air is taken up by overloading of the lungs with blood 

 and edematous fluid, the residual air is therefore diminished. 

 Figure I gives our conception of the condition. A is the calcu- 

 lated normal volume for Patient No. 1. B and C give the 

 observed volume. The conditions found are, in our opinion, 

 brought about not by the mechanism shown in B, but as shown in 

 C, where the black area indicates the space in the chest taken up 

 by^(l) increased size of heart, (2) increase in amount of blood 



