420 THE RESPIRATION 



As has been pointed out elsewhere the increase in the percentage of 

 hemoglobin starts very soon after the rarefied air begins to be breathed, 

 and in confirmation of this it is of interest to note that even at relatively 

 low altitudes Miss Fitzgerald found that changes in the concentration 

 of blood pigment are distinct. The purpose of these changes is no doubt 

 that there may be a larger storehouse of oxygen in the blood from which 

 the necessary tension may be maintained in the plasma. The most im- 

 portant work that remains to be done in mountain sickness is measurement 

 of the acid and ammonia excretion by the kidneys so as to see in how far 

 the observations made in pneumatic cabinets can be confirmed (see page 

 381). 



COMPRESSED-AIR SICKNESS; CAISSON DISEASE; 

 DIVER'S PALSY 



Divers and caisson workers are susceptible to peculiar symptoms. 

 These are frequently of sufficient severity to cause death, but may be so 

 mild as almost to escape notice. They first appear, not when the worker 

 is subjected to the high pressure, but after he has come back to atmos- 

 pheric pressure.* 



While in the compressed air the worker as a rule suffers no discom- 

 fort. A stuffiness may be felt in the ears and temporary giddiness ; the 

 respiration and pulse rate may become slow and frequency of micturition 

 may be noticed, but none of the symptoms of disease appear until after 

 the caissonier or diver has been decompressed (after he has returned to 

 atmospheric pressure), the exact time of their onset being either imme- 

 diately after decompression or at the end of several hours. The worker 

 may have returned home and spent the evening feeling perfectly well 

 until he went to bed, when symptoms supervened which may include mus- 

 cular and joint pains, vertigo, embarrassed breathing, subcutaneous em- 

 physema and hemorrhages, pains in the ears and deaf nessT" vomiting, 

 perhaps hemoptysis and epigastric pain. These symptoms usually pass 

 off after some hours but the arthralgia and myalgia sometimes persist 

 for a considerable time. 



In the more severe cases the first symptom is severe pain in the mus- 

 cles and joints, quickly followed by motor paralysis, so that the patient 

 falls and is likely to become unconscious. The pulse is almost imper- 

 ceptible, the respiration is labored, sometimes even asphyxial, the face 



*A caisson is a steel or wooden chamber sunk in water and prevented from filling by ^means of 

 compressed air. For the passage of the workmen and of material, into and out of the caisson, the 

 latter is connected with a second smaller chamber fitted with air-locks and decompressing cocks. A 

 diver works in a waterproof suit, the head being enclosed in a copper helmet connected by hose with 

 air pumps. Every 10 meters or 33 feet of water corresponds to one atmosphere pressure (IS pounds 

 to the square inch), so that at this depth the total air pressure in a caisson, or in a diver's helmet, 

 would amount to 30 pounds to the square inch, that is, + 1 atmosphere. 



