Symptoms of Decompression 689 



Subchapter II 



COMPARISON OF THE PHENOMENA OF DECOMPRES- 

 SION WITH THOSE OF ASPHYXIA IN CLOSED VESSELS 



I have repeatedly stressed the parallel between the phenomena 

 of decompression and those of asphyxia in closed vessels, a paral- 

 lel continued even in the smallest details. I did so in the first 

 chapter, comparing the duration of life of animals in both situa- 

 tions, under the influence of different conditions. I did so again 

 in regard to the gases contained in the arterial blood in animals 

 under low pressures and in those asphyxiated in closed vessels, 

 when the carbonic acid is removed as it is produced (Chap. II, 

 Subchap. IV). 



The descriptions given by countless authors who have killed 

 animals by asphyxia agree in every point with the phenomena 

 which we have just enumerated. The respiratory rate is shown 

 becoming generally faster at first, then slowing up and appearing 

 very painful when the animal suffers considerably. The pulse 

 rate, in its number and strength, has been much less studied. But 

 the nausea, the frightened movements, the final convulsions in the 

 circumstances which we have specified elsewhere have all been 

 noted. If the phenomena of nutrition have not had sufficient at- 

 tention, we have not forgotten the drop in body temperature, and 

 M. Claude Bernard mentioned the disappearance of the sugar of 

 the liver in slow asphyxia. 



We must note, however, that in the conditions of asphyxia in 

 which these experimenters placed their animals, the carbonic acid 

 was stored up in the surrounding air, without their having deter- 

 mined the influence exerted by this gas, some denying it com- 

 pletely, others exaggerating it grossly. 



The phenomena relating to the decrease in oxygen absorbed, 

 and in the carbonic acid and urea excreted by animals breathing 

 an atmosphere low in oxygen content, have not been studied care- 

 fully enough up to the present. I do not even know any study re- 

 lating to urinary excretion, and that lack is easily understood; it 

 would be exceedingly difficult to keep animals on which such an 

 experiment could be made for a considerable length of time in 

 rarefied air that was suitably renewed. 



As to the absorption of oxygen, while making several successive 

 analyses of the air of a bell in which an animal was slowly 

 asphyxiated, I have very often observed that the animal consumed 



