Oxygenation and Oxidation 



that Riley, Lilienthal, Proemmel and Franke 28 had applied far larger 

 corrections (in our opinion, with doubtful justification) to the data 

 from which their oxygen dissociation curve of arterial blood in vivo 

 was constructed. 



Figure 4. The percentage of 

 oxyhaemogiobin (oxygen satura- 

 tion) of the arterial blood of man. 

 Solid curve, based on composite 

 gasometric data of D. B. Dill 36 

 on blood samples equilibrated in 

 vitro, with pC0 2 = 40 mm and 

 pH = 7*4. The broken curve, 

 based on gasometric measure- 

 ments upon A. V. Bock's blood, 20 

 equilibrated in vitro withpC0 2 = 

 40 mm and pH = 7-4. The 44 

 individual points, based on our 

 direct spectrophotometric 

 analyses for per cent Hb0 2 and 

 corresponding determinations of 

 p0 2 on arterial blood * equili- 

 brated' in vivo. These data 

 have not been ' corrected ' (see 

 the text). 



too 



80 



60 



40 



20 



20 



40 



60 

 mm Hg 



80 100 



Attention may be directed to the following in our data. 



1 Under conditions equivalent to breathing air at sea level, both 

 percentage of Hb0 2 and arterial p0 2 are high. Thus, the findings 

 of Drabkin and Schmidt 10 are confirmed and extended, since suffi- 

 cient corresponding values are now available for both per cent 

 Hb0 2 and/>0 2 (see data in region of 94 to 95 mm/?0 2 , Figure 4). 



2 It may be seen (Figure 4) that data were not obtained below 22 mm 

 of p0 2 (corresponding to about 45 per cent Hb0 2 ). Somewhere 

 in the region of 30 mm p0 2 (with approximately 60 per cent Hb0 2 

 in the arterial blood), unconsciousness set in after breathing the 

 experimental gas mixture for only one minute. Upon revival, 

 the subjects stoutly denied that they had been unconscious. In 

 spite of these protestations, it was not deemed advisable either to 

 prolong the exposure to such moderately low levels of oxygen, 

 or to attempt to attain still lower levels of arterial p0 2 . Riley 

 et al 28 have carried their curve for ' arterial ' oxygen saturation 

 farther, but only by applying appreciable corrections of question- 

 able accuracy to data upon venous blood. 



43 



