Background The concentration of oxygen in air remains constant at 21% regardless of the
altitude. However, the partial pressure of oxygen decreases with increasing altitude …

In the realm of high-altitude medicine, the term high altitude refers to terrestrial elevations
over 1500 m (4921 ft), and is commonly divided into three categories: high altitude, very high …

Mountains and high plateaus cover about one fifth of the Earth's surface and are home to
over 300 million people. 20 At least half of this number live permanently above 2400 meters …

Key Clinical Points Acute High-Altitude Illnesses Acute high-altitude illnesses occur in
persons who are not acclimatized during the first days at an altitude of 2500 m or higher …

Altitude illness affects 25 to 85 percent of travelers to high altitudes, depending on their rate
of ascent, home altitude, individual susceptibility, and other risk factors. Acute mountain …

Barometric pressure falls with increasing altitude and consequently there is a reduction in
the partial pressure of oxygen resulting in a hypoxic challenge to any individual ascending …

High-altitude illnesses encompass the pulmonary and cerebral syndromes that occur in non-
acclimatized individuals after rapid ascent to high altitude. The most common syndrome is …

High-altitude illnesses have profound consequences on the health of many unsuspecting
and otherwise healthy individuals who sojourn to high altitude for recreation and work. The …

As increasing numbers of people choose to sojourn or retire to the mountains, high-altitude
illness is becoming a pathological phenomenon about which healthcare providers should …

Because of a growing interest in adventure travel, improved global travel infrastructure, and
increased access to sites of historical and cultural significance, increasing numbers of …