Studies on Lung Volume 



161 



been present. The residual air we determined indirectly as the 

 difference between total capacity and vital capacity and the mid- 

 dle capacity was determined by rebreathing from a spirometer." 

 The material includes 27 normal subjects ( 18 men and 9 women). 

 The figures for the relative lung volumes reported in a previous 

 communication, are based on the same observations. We ob- 

 tained the following average figure (Table I). It is in approxi- 

 mate agreement with the figures obtained by Lundsgaard and 

 Van Slyke (Table II). The discrepancies are probably due to 

 the fact that the middle capacity, the vital capacity, and the 

 residual air are determined in a slightly different way. (See 

 Lundsgaard and Van Slyke, and Lundsgaard and Schierbeck. 3 

 We believe that the procedure adopted in this paper is the more 

 preferable. The mean error on each determination helps in de- 

 ciding whether or not an observation in a patient may be con- 

 sidered pathological or not. The ratio between the "chest vol- 

 ume" in after maximum inspiration and maximum expiration 

 respectively indicates the range of the thorax movement. 



TABLE I. 



Average values for ratios of " chest volumes" to lung volumes in 27 normal 

 subjects. Ratio of "chest volume' 1 after maximum expiration to " chest 

 volume" after maximum inspiration. Mean error and mean error in per- 

 centage of average figure. 



Position of chest and lungs. 



100 x 



Total lung volume. 



Middle lung capacity. 



100 x - 



Chest volume" in same position. 

 Residual air. 



100 x 



"Chest volume" after full expiration 



Vital capacity. 



100 x ■ 



"Chest volume" in resting position. 



"Chest volume" after full expiration 



100 x 



"Chest volume" after full inspiration 



Abbre- 

 viation. 



Number 

 of 



subjects. 



Average 

 figure. 



Mean 

 error. 



Mean 

 error in 

 percent- 

 age of 

 average 

 figure 



— V 100 

 V 



— x ioo 

 °« 



27 



25 



00.7 



40.3 



3.1 

 4.4 



5.6 

 10.9 



v, 



5-xioo 

 v r 



7^X100 



27 

 27 



18.3 

 49.1 



3.2 

 6.7 



17.5 

 11.6 



c r 



— x ioo 



c t x 



27 



74.7 



5.0 



6.7 



2 Lundsgaard, C, and Schierbeck, K., Paper No. 6 of this series. 



3 Lundsgaard, C, and Schierbeck, Paper No. 6 of this series. 



