214 Chapter XIII 



The actual results which Hartridge (7) obtained may now be given. 

 In the first place he agrees with the now universally accepted opinion 

 that under normal circumstances the oxygen pressure in the alveolar 

 air is very close to that in the blood. 



The following figures show the percentage saturations with CO 

 (A) of the blood of the body and (B) of blood of the same person 

 previously withdrawn, but exposed at body temperature to the alveolar 

 air, a sample of which was taken from the individual. 



Percentage saturation with GO in blood exposed to alveolar air. 



Series 1. Rest. 



(1) (2) (3) (4) (.5) (6) (7) (8) (9) (10) Mean 



A In vivo 12 18 21 29 20 36 35 25 43 44 



B In vitro 10 18'5 225 26'5 15 33-5 33%5 24 42-5 40 



A/B 1-2 -97 -93 1-09 1-3 1'07 1-05 1-Oi 1-01 1-1 1-08 



These figures show that, if anything, there is a trifling excess of 

 CO-haemoglobin in vivo, i.e. a slightly lower oxygen pressure. In two 

 of these experiments Hartridge's blood became 40 / saturated with 

 CO ; up to this point therefore there is no sign of secretion. 



More interesting than these results, however, are those which he 

 obtained whilst establishing a greater or less degree of oxygen want. 



The first method he adopted for this purpose was to breathe 

 mixtures of oxygen, CO and nitrogen which were much poorer in 

 oxygen than is atmospheric air. The following were the results: 



Percentage saturation with CO in Mood exposed to alveolar air. 

 Series 2. Diminished oxygen supply. 



If a comparison be instituted between these oxygen tensions and 

 those which were actually observed by us at the top of Monte Rosa, 

 at an altitude of 15,000 ft., it will be seen that for the most part they 

 correspond to a considerably higher altitude. 



In a third series of experiments Hartridge, whilst breathing from 

 the respiration apparatus, performed a considerable amount of actual 

 physical exercise though not so much as causes dyspnoea to pass into 

 distress ; the following were the figures which Hartridge obtained : 



