154 



Scientific Proceedings (127) 



In hydrogen experiments similar conditions are obtained if 

 the percentage of oxygen is not too low (table 2, Fig. 3). The 

 two curves cross each other and continue a parallel, slightly up- 

 ward course. The point which indicates admixture is indicated 

 by the intersection of the two curves. The hydrogen percentage 

 at this point should therefore be used as indicating the percentage 

 in the system at the time of admixture. Our experiments were 

 performed on normal individuals, on emphysematic patients and 

 on one patient with mitral insufficiency. None of the subjects 

 had a vital capacity below 2 liters and a residual air above 2y 2 

 liters. In all cases a mixture was obtained between after from 

 2 to 6 respirations usually after 3 respirations. The error due 

 to the interchanges between alveolar air and blood gases is as a 

 whole not large. It increases with the duration of the experi- 

 ment and with the degree of difference in tension of the gases in 

 the alveolar air and the blood gases. 



TABLE L 



Analyses of samples of air from bag and from alveoli drawn during one 

 rebreathing oxygen experiment. 



Number of 

 respiration 

 at •which 

 sample is 

 drawn. 



Alveolar air. 



Air from bag. 



Nitrogen, 

 per cent. 



Carbon- 

 dioxide, 

 per cent. 



Nitrogen, 

 per cent. 



Carbon- 

 dioxide, 

 per cent. 



1% 



64.88 



4.39 







2% 











3% 







61.72 



4.49 



4V 2 



62.46 



4.87 







5y 2 



62.61 



5.17 



62.19 



5.10 



ey 2 











7y 2 







62.72 



5.75 



TABLE II. 



Hydrogen experiment. Analyses of samples of air from the first and the very 

 last part of the expiration. The samples are drawn into evacuated 

 recipients. 



Number of respiration 

 at which sample 

 is drawn. 



Percentage of hydrogen 

 in the first part of 

 an expiration. 



Percentage of hydrogen 

 in the very last part 

 of an expiration. 



1% 



4.62 



3.00 



3M> 



5.34 



5.30 



5% 



5.44 



5.48 



7Vo 



5.48 



5.52 



