ACUTE MOUNTAIN SICKNESS

Altitude sickness, also known as ACUTE MOUNTAIN SICKNESS (AMS) or Altitude Illness is a pathological condition that is caused by acute exposure to high altitudes. It commonly occurs above 8,000 feet.

Acute mountain sickness can progress to HIGH ALTITUDE PUMONARY EDEMA or HAPE (fluid in the lungs) or HIGH ALTITUDE CEREBRAL EDEMA or HACE (swelling of the brain).

Different people have different susceptibilities to altitude sickness. For some otherwise healthy people Acute Mountain Sickness (AMS) can begin to appear at around 6,500 feet above sea level such as at many mountain ski resorts. AMS is the most frequent type of altitude sickness encountered. Symptoms often manifest themselves 6 to 10 hours after ascent and generally subside in 1 to 2 days, but they occasionally develop into the more serious conditions. Symptoms are described as headache with fatigue, stomach sickness, dizziness, and sleep disturbance as additional possible symptoms. Exertion aggravates the symptoms.

High altitude pulmonary edema (HAPE) and cerebral edema (HACE) are the most ominous of these symptoms, while acute mountain sickness, retinal hemorrhages, and peripheral edema are the milder forms of the disease. The rate of ascent, the altitude attained, the amount of physical activity at high altitude, as well as individual susceptibility, are contributing factors to the incidence and severity of high-altitude illness.

Altitude sickness usually occurs following a rapid ascent and can usually be prevented by ascending slowly. In most cases, the symptoms are only temporary and usually abate with time as altitude acclimatization occurs. However, in more extreme cases symptoms can be fatal.

SIGNS AND SYMPTOMS

Headache is a primary symptom used to diagnose altitude sickness, although headache is also a symptom of dehydration. A headache occurring at an altitude above 8000 feet, combined with any one or more of the following symptoms, could be an indication of altitude sickness.

* Lack of appetite, nausea, or vomiting

* Fatigue or weakness

* Dizziness or light-headedness

* Insomnia

Additional early indications of altitude sickness may include shortness of breath upon exertion, persistent rapid pulse, drowsiness, general malaise, and peripheral edema (swelling of hands, feet, and face).

Symptoms of life-threatening conditions resulting from extreme altitude sickness include:

* pulmonary edema (fluid in the lungs) - persistent dry cough, fever and shortness of breath even when resting

* cerebral edema (swelling of the brain) - headache that does not respond to analgesics, unsteady walking, increasing vomiting and gradual loss of consciousness.

SEVERE CASES

The most serious symptoms of altitude sickness are due to edema (fluid accumulation in the tissues of the body). At very high altitude, humans can get either high altitude pulmonary edema (HAPE), or high altitude cerebral edema (HACE). These syndromes are potentially fatal. The physiological cause of altitude-induced edema is not conclusively established. For those suffering HACE, dexamethasone may provide temporary relief from symptoms in order to keep descending under their own power.

HAPE occurs in about 2% of those who are adjusting to altitudes of 10,000 feet or more. It can progress rapidly and is often fatal. Symptoms include fatigue, severe dyspnea (shortness of breath) at rest, and cough that is initially dry but may progress to produce pink, frothy sputum. Descent to lower altitudes alleviates the symptoms of HAPE.

HACE is a life threatening condition that can lead to coma or death. It occurs in about 1% of people adjusting to altitudes above 9,000 feet. Symptoms include headache, fatigue, visual impairment, bladder dysfunction, bowel dysfunction, loss of coordination, paralysis on one side of the body, and confusion. Descent to lower altitudes may save those afflicted.

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