An illness that can affect mountain climbers, hikers, skiers, or travelers at high altitude, typically above 8,000 feet.
Due to a combination of reduced air pressure and lower oxygen levels at high altitudes.
Symptoms range from mild to life-threatening.
Acute mountain illness is associated with headaches that occur at increased altitude, and is usually accompanied by anorexia, nausea, dizziness, sleep disturbance, malaise, or combination of these processes.
Acute mountain sickness generally occurs hours after ascension to 2500 m or higher.
The prevalence and severity of the disease process increases with increasing altitude.
Occurs in approximately 10-25% of unacclimatized individuals who ascend to 2500 m, and the symptoms are usually mild at this altitude with little impairment of activities.
Acute mountain sickness occurs in 50-85% of unacclimatized individuals at 4500 to 5500 m, and the the illness may be incapacitating.
Independent risk factors for acute mountain illness include: a history of acute mountain sickness, fast ascent of greater then 625 m per day above 2000 m, and a lack of previous acclimatization, that is, less than five days above 3000 m in the preceding two months.
Additional risk factors include female gender, age younger than 46 years, and a history of migraine.
While exercise may exacerbate acute mountain sickness, good physical fitness is not a protective process.
Affects the nervous system, lungs, muscles, and heart.
Mild symptoms generally associated with mild to moderate acute mountain sickness include: difficulty sleeping, dizziness, fatigue, headache, anorexia, nausea, vomiting, tachycardia, and dyspnea with exertion.
Symptoms associated with more severe acute mountain sickness include: cyanosis, tightness in the chest, cough, hemoptysis, pulmonary congestion, dyspnea, impaired mentation, impaired consciousness, pallor, and impaired balance.
Clinical findings include rales.
Treatment for all forms of mountain sickness is descinding to a lower altitude as rapidly as possible, and the use oxygen therapy.
Symptoms usually respond within 1 to 2 days with appropriate management.
Descent and supplementary oxygen are the treatments of choice.
Severe disease may require hospitalization.
Acetazolamide may be given to help improve breathing and reduce mild symptoms, and can be used as prophylaxis.
Acetazolamide is the drug of choice for prevention of acute mountain sickness.
In severe disease oxygen, nifedipine, phosphodiesterase, beta agonist inhalation therapy, glucocorticoid therapy, and hyperbaric chambers may be utilized.
Severe cases may result in death due to pulmonary or brain edema.
Preventing acute mountain sickness includes climbing gradually, use of acetazolamide, and adequate hydration.
Ibuprofen has been found to be effective chemoprophylaxis of acute mountain illness but is slightly inferior to acetazolomide.