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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 atmospheric air over the range in which humans can survive. [1]
At very high altitude, 3,500 to 5,500 metres (11,500 to 18,000 ft), maximum SaO 2 falls below 90% as the arterial PO 2 falls below 60mmHg. Extreme hypoxemia may occur during exercise, during sleep, and in the presence of high altitude pulmonary edema or other acute lung conditions. Severe altitude illness occurs most commonly in this range.
Re-entry HAPE is also an entity that has been described in persons who normally live at high altitude but who develop pulmonary edema after returning from a stay at low altitude. [3] If HAPE is not treated, there is a 50% risk of mortality. [4] Symptoms include crackling sounds when breathing, dyspnea (at rest), and cyanosis. [4]
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 ...
Hyperpnea is distinguished from tachypnea, which is a respiratory rate greater than normal, resulting in rapid and shallow breaths, but not necessarily increasing volume in breathing. [1] Hyperpnea is also distinguished from hyperventilation , which is over-ventilation (an increase in minute ventilation ), which involves an increase in volume ...
Rapid altitude changes with accompanying changes in ambient pressure exposed the aircrews to an increasing number of episodes of sinus barotrauma. Referred pain from barosinusitis to the maxilla consists about one-fifth of in-flight barodontalgia (i.e., pain in the oral cavity caused by barometric pressure change) cases.
This response can be attributed to genetic factors, but the development of the resistance to acute hypoxia is highly affected by when the individual is exposed to high altitude; [20] while genetic factors play an indefinite role in a person's HVR, because long term migrants do not show reduction in their reactions of high altitude even after ...
High-altitude mountaineering can induce pulmonary hypoxia due to decreased atmospheric pressure. This hypoxia causes vasoconstriction that ultimately leads to high altitude pulmonary edema (HAPE). For this reason, some climbers carry supplemental oxygen to prevent hypoxia, edema, and HAPE.