RESPIRATION 333 



diffuses outwards from the blood much more readily than oxygen 

 diffuses inwards (see Chapter VIII). The deficiency of CO 2 in 

 the arterial blood would prevent or minimize the true hyperpnoea, 

 and lessen the increase of circulation through the tissue capillaries 

 and the pressor excitation of the vasomotor center. But it would 

 increase the true tissue anoxaemia with a given degree of cyanosis. 

 Anoxaemia in the coronary circulation would also lead to the 

 enfeebled action of the heart, as shown by the very weak and 

 feeble pulse. The symptoms generally were those of a pure anox- 

 aemia with urgent danger of failure of the respiratory center in 

 the manner already referred to in Chapter VI. 



In these cases bleeding was of course useless. On the other 

 hand injection into the blood of saline solution or, still better, 

 gum-saline, seemed likely to be of some use in view of the failing 

 blood pressure. By far the most effective treatment, however, was 

 the continuous administration of air enriched with oxygen, par- 

 ticularly if this was begun early and before there was time for the 

 dangerous effects which continued severe anoxaemia causes. By 

 this means the oxygen pressure in the alveolar air was sufficiently 

 raised to permit of a nearly normal aeration of the arterial blood ; 

 and the administration could be continued till the lung inflamma- 

 tion subsided. 



The chronic after effects on the respiratory center of irritant 

 gases have already been referred to in former chapters. 



