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Altitude sickness—also known as acute mountain sickness (AMS), altitude illness, hypobaropathy, "the altitude bends", or soroche—is a pathological effect of high altitude on humans, caused by acute exposure to low partial pressure of oxygen at high altitude. It commonly occurs above 2,400 metres (8,000 feet). It presents as a collection of nonspecific symptoms, acquired at high altitude or in low air pressure, resembling a case of "flu, carbon monoxide poisoning, or a hangover".〔The Mountaineers. Mountaineering: The Freedom of the Hills, 7th Edition. Seattle, WA: Mountaineers Books, 2003〕 It is hard to determine who will be affected by altitude sickness, as there are no specific factors that correlate with a susceptibility to altitude sickness. However, most people can ascend to 2,400 metres (8,000 ft) without difficulty. Acute mountain sickness can progress to high altitude pulmonary edema (HAPE) or high altitude cerebral edema (HACE), which are potentially fatal.〔 Chronic mountain sickness, also known as ''Monge's disease'', is a different condition that only occurs after very prolonged exposure to high altitude.〔A.J. Giannini, H.R. Black, R.L. Goettsche. The Psychiatric, Psychogenic and Somatopsychic Disorders Handbook. New Hyde Park, NY. Medical Examination Publishing Co.,1978. pp.190,192. ISBN 0-87488-596-5.〕 ==Definitions== *High altitude: - The onset of physiological effects of diminished inspiratory oxygen pressure (PiO2) includes decreased exercise performance and increased ventilation (lower arterial PCO2). Minor impairment exists in arterial oxygen transport (arterial oxygen saturation (SaO2) at least 90%), but arterial PO2 is significantly diminished. Because of the large number of people who ascend rapidly to altitudes between 2,400 and 4,000 m, high-altitude illness is common in this range. *Very high altitude: - Maximum SaO2 falls below 90% as the arterial PO2 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.〔 *Extreme altitude: above - Marked hypoxemia, hypocapnia, and alkalosis are characteristic of extreme altitudes. Progressive deterioration of physiologic function eventually outstrips acclimatization. As a result, no permanent human habitation occurs above A period of acclimatization is necessary when ascending to extreme altitude; abrupt ascent without supplemental oxygen for other than brief exposures invites severe altitude sickness.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Altitude sickness」の詳細全文を読む スポンサード リンク
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