250 TREATMENT OF DECOMPRESSION SYMPTOMS 



In a few seconds the cat became entirely paralysed in the 

 limbs so that it fell helpless on to its side. On recompression, 

 the symptoms gradually disappeared. Some two or three minutes 

 after recompression the cat tried to walk. The pressure was 

 maintained for 45 minutes and then slowly lowered. The cat 

 recovered and on removal seemed perfectly normal. 



The rabbit was recompressed before it showed any symptoms of 

 decompression, and was quite normal on removal from the chamber. 



All our experiments show that for 8 atm. 2 hours is a safe 

 period for decompression. The only case in which it fails is when 

 the animals have developed symptoms of oxygen -poisoning and 

 have become comatose, their body temperature lowered and lungs 

 congested by too long a stay in the compressed air. The 

 circulatory and respiratory organs then fail to rid the body of 

 the gas with which it is saturated. 



The post-mortem examinations of men stricken with divers' 

 palsy paraplegia, decubitus, paralysis of sphincters show ex- 

 tended necrosis in the region of the posterior and lateral columns 

 of the cord, especially in the cervical region. The necrosis 

 is due to ischaemia produced by air embolism. The necrotic 

 tissue consists of the detritus of nervous tissue, and overgrowth 

 of glia tissue. The blood-vessels are distended by the air-bubbles, 

 and the corpuscles driven into clumps which resemble small 

 haemorrhages (von Schrotter). Recompression has been found to 

 alleviate the minor symptoms, such as "bends" which occur in 

 caisson- workers. Prevention is, however, better than cure, and ex- 

 perimental evidence shows that the grave symptoms can be entirely 

 eliminated by making the period of decompression last one to 

 two hours. The periods of decompression used at present in caisson- 

 works are far too short, 1 and there can be no doubt that the 

 men very frequently must have bubbles of nitrogen set free in 

 their blood. Whether this produces ill effects is largely a matter 

 of chance. Young men with elastic arteries who are deep 

 breathers and of spare habits, are least likely to suffer, for being 

 spare they will dissolve less gas, while their arteries being elastic 

 will be less easily blocked by air-bubbles, and the dissolved air will 

 quickly be expelled by the vigour of their pulmonary ventilation. 

 For deep-sea work the writer has designed a diving-bell into 

 which divers can enter and enclose themselves after completion 



1 Twenty minutes per atm. is a safe rule. 



