CLIMATE 907 



pressure, acting in a mechanical manner, as the responsible cause. It has 

 been natural to expect that a diminution of external pressure would have a 

 "cupping glass" effect that would lead to a congestion of the skin and 

 lungs and in some way cause a readjustment of internal parts of the body. 

 However, all recent investigators hold that the physiological effects noted 

 at high altitudes are due to the lack of oxygen, resulting from the lowered 

 partial pressure of oxygen that occurs proportionately with the decrease 

 in barometric pressure. 



Altitude Sickness. It is now clearly established that during the first 

 few days spent at a high altitude an attack of altitude sickness may occur. 

 Some persons are affected at a comparatively low and others at a higher 

 altitude. An elevation of 10,000 feet, or even less, provokes it in a few 

 individuals; but many go to 14,000 and more feet without distress. 

 There are two forms of altitude ("mountain") sickness; the acute, which 

 breaks out suddenly on entrance into the rarefied air ; and the slow, which 

 manifests itself much later. 



The acute form is characterized by a rapid pulse, nausea, vomiting, 

 physical prostration which may even incapacitate for movement, livid 

 color of the skin, ringing sensation in the ears, dimmed sight and faint- 

 ing attacks. 



In the slow form, which may be called the normal type, lasting from 

 one to three days, the newcomer at first complains of no symptoms. Some 

 hours later he begins to feel "good for nothing" and disinclined for 

 exertion. He goes to bed to spend a restless and troubled night. A frontal 

 headache and periodic or Cheyne-Stokes breathing interfere with sleep, 

 there may be nausea and vomiting. The next morning the patient may 

 feel slighly giddy on arising and any attempt at exertion increases the 

 headache. The face may be slightly cyanosed and the eyes dull and heavy, 

 with a tendency to water. The tongue is coated and appetite gone. There 

 may be diarrhea and abdominal pain. The pulse and arterial blood 

 pressure are usually high. The temperature is normal or slightly under. 

 There are wide divergencies from this slow type of which Ravenhill has 

 well described those in which cardiac and nervous symptoms predominate. 

 A weakened heart does not seem to predispose to the cardiac type of 

 altitude sickness. 



Acclimatization. The process of acclimatization is slow, while certain 

 of the changes may begin almost at once with entrance into rarefied air, 

 it ordinarily requires several days for these to wholly restore the patient 

 to normal well being. The complete process of acclimatization requires 

 six and more weeks. 



Adaptation to altitude consists in physiological responses that increase 

 the supply of oxygen, which is at first decreased because of lowered 

 pressure, until it again reaches normal. These include, among others, the 

 following: (1) An increase in the percentage and the total amount of 



