CLIMATE 911 



altitude normal. The same amount of physical exertion increases the 

 pulse rate more at a high than at a low altitude. The difference becomes 

 greater as the amount of work done increases. 



The arterial blood pressures are not altered by altitude in the majority 

 of men ; but in a considerable number of cases there occurs a slight lower- 

 ing of the systolic pressure; while occasionally, very likely in a poor 

 reactor, there is a rise in both the systolic and diastolic pressures. During 

 an attack of "altitude sickness" there is usually a marked increase in 

 both pressures. 



The blood pressure in the capillaries is either unchanged or less than 

 at sea-level. In the veins, at altitudes of more than 6,000 feet, the pressure 

 is less than at sea-level. Contrary to common opinion bleeding from the 

 nose, lips, lungs, and stomach rarely occurs. The experience of aviators 

 has dispelled the belief that altitude causes hemorrhages. 



Physical exertion makes greater demands on the heart and blood vessels 

 at high than at low altitudes. The rise in arterial pressure is greater 

 for a given exertion at a high than a low altitude, the difference being 

 less after acclimatization. It would be an easy matter to seriously injure 

 the heart during the early days of residence at high altitude. However, 

 in men who are physically strong because of athletic training the risk is 

 slight; and in all who become acclimated the ordinary forms of exercise 

 will be well tolerated. 



General Considerations. Anemia is regarded by Sewall as the domi- 

 nant disorder at high altitudes. Anemia reduces the working efficiency 

 and the reserve power of the tissues insofar as it permits deprivation of 

 oxygen. That the physiological response to the stimulation of lowered 

 barometric pressure may be slow or deficient is a common observation. 

 Hence it is to be expected that many functional disorders are originated 

 or accelerated at moderate altitudes owing to the existence of com- 

 paratively mild grades of anemia. Moleen has called attention to the 

 fact that individuals who exhibit nervous symptoms or complain of 

 "nervousness" while living at high elevations show a relative or abso- 

 lute anemia. It is significant that the plethoric type of person rarely 

 finds it necessary to leave high altitudes for "nervousness." It is main- 

 tained that if measures are taken to stimulate the blood forming centers 

 there is no more difficulty in living tranquil lives in the high altitudes 

 than at sea level. 



The dangers to the heart in high altitudes are, according to Hall, 

 precisely the same as elsewhere, but very sharply exaggerated in certain 

 directions; particularly because the newcomer is likely to overdo in 

 physical exertion. Cardiac overstrain from exercise is often the real cause 

 of distress and not the altitude. Schrumpf found in Switzerland that up 

 to 7,000 feet pathological blood pressures are improved, that is, high 

 pressures are reduced and low ones increased, together with an improve- 



