ENLmedical.com: Conditions And Concerns: Medical Encyclopedia: Acute mountain sickness

Acute mountain sickness

Causes and Risks:
Reduced atmospheric pressure and oxygen pressure at high altitude are the causes of this illness. It affects the nervous system, lungs, muscles, and heart. The faster the ascent and the greater the altitude are factors that affect the degree of illness. In most cases the symptoms are mild, but in severe cases extreme shortness of breath with fluid buildup in the lungs (called pulmonary edema ) develops. Swelling may occur around the brain, causing confusion and leading to coma . The incidence is 2 out of 10,000 people.

Prevention:
Education of mountain travelers before ascent is the key to prevention. Basic principles include: gradual ascent, stopping for a day or two of rest for each 2,000 feet (600 meters) above 8,000 feet (2,400 meters); sleeping at a lower altitude when possible; attaining optimal physical conditioning before ascent; and learning how to recognize early symptoms so the party can return to lower altitude before worsening symptoms occur.

Mountaineering parties traveling above 9,840 feet (3,000 meters) should carry an oxygen supply sufficient for several days.

Acetazolamide (Diamox) may be given as a preventive medication, but therapy must be started before ascent to altitude. Do not consume alcoholic beverages while taking Diamox.

People with underlying cardiac or pulmonary (lung) diseases should avoid high altitudes.

Symptoms:

dry, continuous cough
shortness of breath
- at rest
- aggravated by exercise
dizziness
headache
- upon awakening in the morning
- awakens patient from sleep
- aggravated by lying down, reclining position
- aggravated by standing up
- aggravated by coughing, sneezing , straining, lifting (Valsalva maneuver)
- with nausea or vomiting
sleeping difficulty
rapid pulse ( heart rate )
loss of appetite
nausea
vomiting
confusion
coughing up blood
fatigue

Additional symptoms that may be associated with this disease:

transient, temporary vision abnormalities
eyelid drooping on one side only (unilateral)
facial swelling
swelling in both legs (lower extremities)
swelling around the eye socket (periorbital)
eyes, pupils different size
- pupil enlarged (dilated) in one eye only (unilateral)
consciousness, decreased or withdrawal from social interaction

Signs and Tests:
Listening to the chest with a stethoscope ( auscultation ) reveals crackles in the lung fields.

A chest X-ray may be performed.

Treatment:
The objective of treatment is to descend to lower altitude as rapidly and safely as possible and to begin oxygen therapy as soon as possible--in the field if available.

Hospitalization may be required for severe illness.

Supportive measures include oxygen by mask or by mechanical ventilation if respiratory distress or pulmonary edema is present, and rest. The affected person will breathe easier in a sitting position.

Diuretics are prescribed for pulmonary edema (see furosemide - oral).

Prognosis:
Most cases are mild and symptoms improve with a return to lower altitude. Severe cases may result in death due to respiratory distress or coma .

In remote locations emergency evacuation may not be possible or treatment may be delayed. These conditions could affect the outcome.

Complications:

pulmonary embolism
pulmonary edema
coma
high altitude cerebral edema (brain swelling )

Call Your Healthcare Provider:
Call your health care provider if symptoms of acute mountain sickness develop, even if symptoms resolved when returning to a lower altitude.

Go to the emergency room or call the local emergency number (such as 911) if severe difficulty breathing develops, if consciousness is decreased, if coughing up blood , or if other severe symptoms are present.