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Altitude sickness, the mildest form being acute mountain sickness (AMS), is a harmful effect of high altitude, caused by rapid exposure to low amounts of oxygen at high elevation. [ 1 ] [ 2 ] [ 3 ] People's bodies can respond to high altitude in different ways.
The effects of high altitude on humans are mostly the consequences of reduced partial pressure of oxygen in the atmosphere. The medical problems that are direct consequence of high altitude are caused by the low inspired partial pressure of oxygen, which is caused by the reduced atmospheric pressure, and the constant gas fraction of oxygen in ...
High-altitude adaptation in humans is an instance of evolutionary modification in certain human populations, including those of Tibet in Asia, the Andes of the Americas, and Ethiopia in Africa, who have acquired the ability to survive at altitudes above 2,500 meters (8,200 ft). [1]
High-altitude pulmonary edema (HAPE) is a life-threatening form of non-cardiogenic pulmonary edema that occurs in otherwise healthy people at altitudes typically above 2,500 meters (8,200 ft). [2] HAPE is a severe presentation of altitude sickness .
Atmospheric pressure decreases with altitude while the O 2 fraction remains constant to about 85 km (53 mi), so PO 2 decreases with altitude as well. It is about half of its sea level value at 5,500 m (18,000 ft), the altitude of the Mount Everest base camp , and less than a third at 8,849 m (29,032 ft), the summit of Mount Everest. [ 8 ]
CMS was first described in 1925 by Carlos Monge Medrano, a Peruvian doctor who specialised in diseases of high altitude. [3] While acute mountain sickness is experienced shortly after ascent to high altitude, chronic mountain sickness may develop only after many years of living at high altitude. In medicine, high altitude is defined as over ...
Others, like reduced oxygen tension at high altitude, may be regionally distributed or associated with a specific demographic. [8] Generalized hypoxia is an occupational hazard in several high-risk occupations, including firefighting, professional diving, mining and underground rescue, and flying at high altitudes in unpressurised aircraft.
It is initially elevated in lowlanders who travel to high altitude, but reduces significantly over time as people acclimatize. [1] [2] In biological anthropology, HVR also refers to human adaptation to environmental stresses resulting from high altitude. [3] In mammals, HVR invokes several physiological mechanisms.