Mountain sickness
Key points
- Acute mountain sickness is an illness that can affect mountain climbers, hikers, skiers, or travelers who ascend too rapidly to high altitude (typically above 8,000 feet or 2,400 meters).
- Reduced atmospheric pressure and a lower concentration of oxygen at high altitude are the causes of this illness.
- Listening to the chest with a stethoscope (auscultation) reveals crackles in the lung fields in patients with pulmonary edema.
- The mainstay of treatment for all forms of altitude illness is to descend to lower altitude as rapidly and safely as possible.
Alternative names
High altitude cerebral edema; Altitude anoxia; Altitude sickness; Acute mountain sickness; High altitude pulmonary edema
Definition
Acute mountain sickness is an illness that can affect mountain climbers, hikers, skiers, or travelers who ascend too rapidly to high altitude (typically above 8,000 feet or 2,400 meters). This is especially for persons who normally reside at or near sea level.
Causes, incidence, and risk factors
Reduced atmospheric pressure and a lower concentration of oxygen at high altitude are the causes of this illness. It affects the nervous system, lungs, muscles, and heart. Symptoms can range from mild to life-threatening.
In most cases the symptoms are mild, but in severe cases fluid collects in the lungs (pulmonary edema) causing extreme shortness of breath and further decreasing oxygenation. Swelling may also occur in the brain (cerebral edema), causing confusion, coma, and, if untreated, death.
The likelihood and severity of altitude illness is greater with increasing rate of ascent, higher altitude attained, and higher levels of exertion.
Approximately 20% of people will develop mild symptoms at altitudes between 6,300 to 9,700 feet, but pulmonary and cerebral edema are extremely rare at these heights. However, above 14,000 feet, a majority of people will experience at least mild symptoms, while approximately 10% and 1.5%, respectively, of un-acclimatized people staying at this altitude will develop pulmonary or cerebral edema.
Symptoms
Symptoms generally associated with mild to moderate altitude illness include:
- headache
- Difficulty sleeping
- Loss of appetite
- Nausea or vomiting
- Fatigue
- Dizziness or light-headedness
- Rapid pulse (heart rate)
- Shortness of breath with exertion
Symptoms generally associated with more severe altitude illness include:
- Cough
- Shortness of breath at rest
- Chest tightness or congestion
- Bluish discoloration of the skin
- Coughing up blood
- Inability to walk in a straight line, or to walk at all
- Decreased consciousness or withdrawal from social interaction
Written and revised by
Andrey Nailor, M.D.
Our doctors write and review articles for accuracy and keep them up to date.
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