Prophylaxis of Sudden Decompression 891 



From 3:25 to 4:05 was taken again to 7 atmospheres, and kept 

 there until 4: 12. Then decompressed slowly; normal pressure was 

 reestablished at 6 o'clock. 



On leaving the apparatus, the animal is still paralyzed in the 

 hindquarters, or rather, its hind legs, stiff and contracted, no longer 

 are controlled by the will; sensitivity remains, and we obtain reflex 

 movements by pinching, but very slowly. 



Dies during the night. 



Experiment DLXXXVIII. October 16. Dog of Experiment DXXXVII. 



Paraplegic and stiff since 2 o'clock, as a consequence of a decom- 

 pression from 7 atmospheres. Recompressed to 7 atmospheres from 

 2: 15 to 3:02, then decompressed in an hour. 



The animal seems better and calmer; but it is still paraplegic 

 though not stiff; the temperature of the hind legs has risen. 



Dies the next day. 



No gas is found in the vessels; but the spinal cord presents, from 

 the lumbar enlargement to the middle of the dorsal region, little 

 bloody spots scattered in the antero-lateral fasciculi. There is no 

 softening. 



I did not multiply these experiments; it is evident that the 

 recompression was managed here too slowly for it to be possible 

 to draw any conclusion from these results. However, I do not 

 doubt the effectiveness of this method, on condition that one could 

 obtain a very rapid recompression. We saw in the historical part 

 that it was already used by workmen and recommended by the 

 physicians who had attended them. 



The considerations already presented (Page 884) had put me on 

 the track of a quite different method, which aimed not at redissolv- 

 ing the bubbles of free gases in the blood, but at forcing them to 

 escape through the respiration. 



These bubbles are composed, I have said, of nitrogen; when 

 they reached the pulmonary capillaries, there is not much likeli- 

 hood that they will be diffused and mingle with the air of the 

 lungs, because that air also is four-fifths composed of nitrogen. 

 Considering this, I thought that if the animal were caused to 

 breathe a gas containing no nitrogen, pure oxygen, for example, 

 the diffusion would take place much more rapidly, and perhaps 

 would even be rapid enough to cause all the gas to disappear from 

 the blood, and thus save the animal. I' give here the results of some 

 experiments performed in this way: 



Experiment DLXXXIX. October 31. Dog of Experiment DXLIII. 

 Decompressed from 7 V 4 atmospheres, lying down, very sick since 

 2: 15, with gurgling in the heart. 



At 2:20, pure oxygen administered to him continuously. 



At 2:30, the sound of gurgling has ceased, respiration is freer, 



