ALTITUDE SICKNESS

High altitudes are low oxygen environments. As you go up, an adequate oxygen supply is maintained by various compensations such as increases in breathing rate and heart rate. High altitude causes fluid shifts that may lead to swelling of the hands, face, and feet. Rapid exposure to altitudes of 7,000 to 8,000 feet or more (for comparison, most Colorado ski resorts are near 9,000 feet) may overwhelm your body's ability to adapt, potentially leading to such altitude illnesses as acute mountain sickness, high- altitude pulmonary edema, and high-altitude cerebral edema.

Acute mountain sickness (AMS) is characterized by headache, nausea, vomiting, shortness of breath, difficulty sleeping, dizziness, and malaise, which typically occur 6 to 48 hours after ascent. Symptoms may be mistaken for alcohol hangover, exhaustion, or infection. Acute mountain sickness is the most common altitude-related illness; 25% of individuals may be affected at 7,000 feet and as many as 50% at 15,000 feet. Men and women are equally susceptible, yet younger adults may be more vulnerable. Acute mountain sickness is also more common in individuals with underlying lung problems, previous history of AMS, and those who usually live at sea level.

High-altitude pulmonary edema refers to the abnormal accumulation of fluid in the lungs at altitudes higher than 8,000 feet. This is a life-threatening condition that often strikes young, fit climbers who have made previous trips to high altitudes without problems. Symptoms usually develop within 2 to 4 days and begin with decreased exercise performance. Symptoms of AMS may also be present. Later symptoms may include cough, chest congestion, shortness of breath at rest, decreased level of alertness, and incoordination.

High-altitude cerebral edema is an illness caused by brain swelling. Severe headache, walking problems, and mental dysfunction (hallucinations, reduced responsiveness, and even coma) are the characteristic symptoms. This is a life-threatening condition and frequently occurs together with high-altitude pulmonary edema.

Treatment of altitude-related conditions depends on the severity of the illness and the environment. Symptoms of AMS usually spontaneously resolve in as little as 1 to 3 days. Some minor symptoms, such as headache, can be treated with acetaminophen or aspirin. More significant symptoms can be relieved with descent or drugs such as acetazolamide, which stimulates breathing and helps prevent fluid retention.

For high-altitude pulmonary edema, rest and supplemental oxygen are usually the initial treatments. For severe illness or when oxygen is not available, descent is mandatory.

Immediate descent and oxygen therapy are recommended for high-altitude cerebral edema to help prevent serious neurologic damage or death. Dexamethasone, a steroid, is often used to help prevent or reduce brain swelling.

• The most effective preventive measure for altitude-related illness is a gradual ascent allowing for 2 to 4 days of acclimation at altitudes of 6000 to 8000 feet before ascending to higher elevations.
• Discuss with your health care provider the need for drug therapy to help prevent altitude-related illness. Acetazolamide is often used to prevent altitude-related symptoms. It is usually started 1 to 2 days before ascent and continued for 2 or more days at high altitude. The most common side effects are nausea and numbness/tingling of the lips, fingers, and toes. Acetazolamide preventive therapy is usually reserved for those known to be at risk for AMS or for those who must reach altitude very quickly.

• Avoid alcohol and sleeping pills at high altitude because they may worsen both sleep quality and AMS symptoms.
• Avoid overexertion when initially arriving at high altitude. Unfortunately, exercise before traveling to high altitude does not help prevent altitude-related illnesses.
• Avoid acetazolamide if you are allergic to sulfa drugs.
• Avoid reexposure to high altitude if you have had previous problems with high-altitude pulmonary edema or high-altitude cerebral edema.

• Altitude-related illness may occur in an area where contact with a doctor is not possible. The development of neurologic or respiratory problems should be taken very seriously and should initiate as safe and quick of a descent as possible.

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