Mountains have fascinated and attracted humankind for millennia. Most peaks in the Alps had been climbed by the end of the 19th century. Some early climbers mentioned experiencing the symptoms now described as mountain sickness. By the beginning of the 20th century, hypobaric hypoxia was known to be the main cause of these symptoms. Even today, many questions regarding the precise mechanism of altitude illness remain unanswered.
Despite the obvious dangers inherent in climbing and the altitude-related illness experienced by nearly all who spend significant time in the mountains, people continue to seek the remoteness and pleasures of high places. With the availability of easy transportation into the mountains, not just for climbing but also for skiing and other forms of recreation, thousands are exposed to high altitude each year. These individuals frequently experience acute illness soon after ascent. With longer stays at altitude, these symptoms improve in a process known as acclimatization.
This article describes the various medical problems associated with ascent to high altitude, amelioration of altitude-related symptoms through acclimatization, and treatment of the disorders when they occur.
A multitude of problems is associated with ascent to altitude. Some of these are merely an annoyance while others are life threatening. Three major syndromes, acute mountain sickness (AMS), high-altitude pulmonary edema (HAPE), and high-altitude cerebral edema (HACE), are now commonly accepted
. Other related problems, such as impaired sleep and high-altitude retinal hemorrhage, often coexist with the major syndromes and deserve mention. Finally, the effects of ascent on certain special populations are briefly discussed.