I50 RESPIRATION 



the graver cases the anoxaemia was usually unaccompanied by 

 distention of the lips and veins with blood, and the cyanosis was 

 thus of the leaden or gray type, just as in cases of slowly advancing 

 anoxaemia from other causes. In death from gradual CO poison- 

 ing, for instance, there is no extra distention of the lips or veins 

 with blood, although, of course, the lips are not gray but light 

 pink. Death, in the phosgene cases and probably in others, seems 

 to have been finally due to failure of the respiratory center, the 

 breathing becoming more and more shallow till the resulting 

 increase in the anoxaemia ended in death. Orthopnoea was a very 

 common symptom so long as the men were conscious. 



In favorable cases of ordinary croupous pneumonia the lips 

 remain of a good color, and there are no evident signs of anoxae- 

 mia; but the breathing is rapid, and correspondingly shallow. 

 The danger of anoxaemia is therefore not far off. At Cripple 

 Creek (at an altitude of about 10,000 feet) I was told that cases of 

 commencing pneumonia were at once put on the train and sent 

 down to the prairie level, as it had been found that they had a 

 very poor chance if treated locally. This indicates the danger 

 from anoxaemia, and led us, in the Report of the Pike's Peak 

 Expedition, to advocate the use of chambers containing air en- 

 riched with oxygen for treating pneumonia. The fact that there 

 is often no cyanosis in spite of very extensive lung consolidation 

 seems to show that the pulmonary circulation has practically 

 ceased in the consolidated areas. The blood supply of these areas 

 may be solely through the bronchial arteries, the high-pressure 

 supply from which joins the pulmonary circulation. This inference 

 has recently been confirmed by Gross,^^ who found by means of 

 X-ray photographs of lungs injected with an injection mass 

 opaque to X-rays, that the pulmonary vessels are nearly blocked 

 off in the consolidated parts in pneumonia. In the unaffected parts 

 of the lungs, the oxygen seems to penetrate the alveolar walls 

 readily enough in pneumonia. Where anoxaemia becomes danger- 

 ous in croupous or disseminated pneumonia it seems usually to be 

 failure of the respiratory center and consequent shallow breathing 

 that is mainly responsible for the anoxaemia. 



The fact that in pneumonias of all kinds the arterial blood is 

 commonly more or less imperfectly saturated with oxygen has 

 quite recently been shown directly by Stadie,^^ who examined 



"Gross, Canadian Med. Assoc. Journ., p. 632, 19 19. 

 " Stadie, Journ. of Exper. Med., XXX, p. 215, 19 19. 



