48
ataxia, progressing to obtundation and eventually coma. Immediate descent is mandatory
until obvious improvement occurs. Oxygen and dexamethasone are recommended as
adjunctive therapy with descent. Supplemental oxygen is titrated to achieve an SaO2 of
90 % or greater. Be observant for concomitant HAPE. Dexamethasone 8-12 mg is given
immediately by the route most easily available, followed by 4 mg every 6 hours until
symptoms subside. Response is usually noted within 12 to 24 hours, but descent is still
mandatory and ataxia may be slow to resolve even after descent and treatment with
oxygen and dexamethasone. Hospitalization is commonly required after evacuation from
high altitude and treatment may include endotracheal intubation for airway protection and
treatment of increased intracranial pressure. If descent is not possible in a field setting
because of weather or terrain conditions, then a portable hyperbaric bag may be used to
simulate descent as a temporizing measure.
D. Peripheral Edema: High-altitudes may cause swelling of the hands, ankles, or face
(usually the periorbital region). Elevate the extremities, if possible. The edema will
resolve with descent, but descent is not mandatory unless signs and symptoms of more
serious altitude illnesses are present.
E. High Altitude Retinopathy: Retinal hemorrhages are common above 16000 feet (5000
meters), but may develop at lower altitudes. They are generally asymptomatic and do not
warrant descent or other treatment. However, when a retinal hemorrhage overlies the
macula it may cause blindness. They usually resolve after descent, although a blind spot
may persist for years or permanently.
IV. REFERENCES
A. Reviews Supporting All Category 1A Recommendations
Grissom CK,
Schoene RB. Adaptation and maladaptation to high altitude. In:
Crapo JD, Glassroth J, Karlinsky J, King TE, Jr. (eds.) Baum's Textbook of Pulmonary
Diseases, 7
th
edition. Philadelphia: Lippincott Williams & Wilkins, 2004: 1005-23.
Hackett PH, Roach RC. High altitude illness N Engl J Med 2001; 345: 107-14.
Hackett PH, Roach RC. High altitude medicine. In: Auerbach PS. Wilderness
Medicine 4
th
edition. St. Louis, MO: Mosby, 2001: 2-43.
Bartsch P, Roach R. Acute mountain sickness and high-altitude cerebral edema.
In: Hornbein TF, Schoene RB, (eds.) High Altitude, An Exploration of Human
Adaptation. From: Lung Biology in Health and Disease, Lenfant C, exec (ed.) New York:
Marcel Dekker, Inc., 2001; 731-76.
Schoene RB, Hackett PH, Hornbein TF. High altitude. In: Murray JF, Nadel JA.
(eds.) Textbook of Respiratory Medicine, 3
rd
ed. New York: W.B. Saunders Co, 2000:
1915-50.
B. Studies Supporting Category 1A Recommendation of Gradual Ascent for Prevention
of High Altitude Illness
Hackett PH, Rennie D, Levine HD. The incidence, importance, and prophylaxis
