1 62 RESPIRATION 



vision and hearing impaired, and intelligence probably greatly 

 impaired. It was also hardly possible to rise from the chair with- 

 out assistance. Writing was very bad, and spelling uncertain. 

 Movements were very uncertain, and it was difficult to recognize 

 objects distinctly or estimate their distance correctly, so that things 

 a long way off were grasped at in vain. Attempts to go any distance 

 caused failure of the legs and collapse on the floor. In one experi- 

 ment the saturation reached 56 per cent. It was then hardly 

 possible to stand, and impossible to walk. After each of these 

 experiments the saturation of the blood fell rapidly when fresh 

 air was breathed ; and within three hours the saturation had fallen 

 below 20 per cent. 



Shortly after these experiments, I examined the bodies of a 

 large number of men who had been killed in colliery explosions, 

 and found that nearly all had died of CO poisoning. The satura- 

 tion of the haemoglobin with CO was usually about 80 per cent, 

 but in some cases not more than 60 per cent. In fatal cases of 

 poisoning by lighting gas Lorrain Smith found similar satura- 

 tions. 



The general similarity between the symptoms of CO poisoning 

 and those of anoxaemia produced in other ways is evident; and 

 the after-symptoms appear to be identical with those of mountain 

 sickness and related disorders. There is, however, a difference 

 between the symptoms of CO poisoning and those of anoxaemia 

 produced by imperfect oxygenation of the arterial haemoglobin. 

 This difference lies in the fact that in CO poisoning fainting, or a 

 tendency to fainting, is much more prominent than respiratory 

 distress. A man at a high altitude pants excessively on exertion, 

 but does not easily faint. A man suffering from CO poisoning 

 faints very readily on exertion, and the tendency to dizziness and 

 collapse is far more prominent than the hyperpnoea. The fainting 

 on exertion is evidently due to the fact that from lack of the mass 

 of oxygen needed the heart cannot compensate by sufficiently 

 increased output of blood for the greatly increased flow of blood 

 through the working muscles. The blood pressure therefore falls, 

 with the result that the circulation to the brain is diminished and 

 anoxaemia then causes loss of consciousness. But why does this 

 occur so much more readily in CO poisoning? The fact that it does 

 so indicates that relatively speaking the respiratory center is less 

 affected in the anoxaemia of CO poisoning, in which the mass of 

 oxygen in the blood is reduced but the pressure of oxygen in the 

 arterial blood remains normal. That is to say, with a degree of 



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