RESPIRATION 353 



conditions of apparently the most desperate character. It would 

 have taken over four hours to bring him up at all safely by stage 

 decompression, and his blood was certainly full of bubbles before 

 he was got into the chamber. 



The difficulty of safe decompression in the chamber is one that 

 has often been met with before in bad cases. It may be necessary 

 to keep a patient in the chamber for 24 hours or more. 



In work in tunnels or caissons the pressures encountered are 

 not nearly so high as in diving work; but the durations of ex- 

 posure are usually a good deal longer. Hitherto the time given to 

 decompression in the air lock has hardly ever been sufficient to 

 prevent symptoms, though in recent years it has often been suffi- 

 cient to prevent almost entirely the very dangerous symptoms 

 produced by rapid decompression, which leaves most of the body 

 in a condition of supersaturation with nitrogen. On this account 

 most of the symptoms in tunnel workers, etc., consist of the 

 "bends," itching of the skin, etc., due to bubbles in the tissues 

 which saturate and desaturate very slowly. In divers, on the 

 contrary, the symptoms met with before stage decompression was 

 introduced were mostly of a far more serious character, and due 

 to wholesale formation of bubbles in the blood and in tissues which 

 saturate and desaturate fairly quickly. Death or more or less 

 permanent paralysis were therefore common. With shortened 

 stage decompression it is usually the less serious symptoms which 

 appear among divers, and if the stage decompression is shortened 

 these symptoms must be expected. It is unfortunate that stage 

 decompression cannot be introduced in some countries on account 

 of antiquated state regulations enjoining decompression at a 

 constant rate, or even decompression starting very slowly and 

 increasing in rate as atmospheric pressure is approached. 



During decompression, or immediately after it, it is very de- 

 sirable that as much muscular work as possible should be carried 

 out, so as to increase the circulation, and therefore the rate of 

 desaturation, over all parts of the body, and particularly those 

 parts which, owing to muscular exertion during exposure to the 

 high pressure, may have become saturated to a greater extent 

 than would otherwise be the case. For this reason the naval divers 

 were enjoined to keep their arms and legs moving as much as 

 possible during the stoppages at each stage. Bornstein has more 

 recently brought forward evidence collected at the Elbe tunnel 

 works that muscular exertion just after decompression diminishes 

 greatly the liability to "bends." 



