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consists of administering supplemental oxygen by nasal cannula at a flow to achieve an
arterial oxygen saturation (SaO2 %) of greater than 90% as measured by a digital pulse
oximeter, or about 2 liters per minute flow if measurement of oxygen saturation is not
available. Oxygen may be especially helpful during sleep. Aspirin or acetaminophen,
with hydrocodone if necessary, are useful for headache. Prochlorperazine or
promethazine can be used for nausea. Prochlorperazine 10 mg parenterally or orally
every 6 hours, or 25 mg rectally every 12 hours, for an average-size adult, also increases
the hypoxic drive to breathe. Promethazine can be administered as 25 mg parenterally, or
as 25 or 50 mg suppositories for adults every 8 hours. Use no more than three doses of
either drug. Note that both prochlorperazine and promethazine may cause extrapyramidal
reactions requiring treatment with diphenhydramine. Treatment of the illness, rather than
just the symptoms, requires acetazolamide. The treatment dose is 250 mg twice a day.
Acetazolamide speeds acclimatization and aborts the illness. An alternative for persons
who are sulfa allergic is dexamethasone 4 mg every 6 to 8 hours. A response is usually
seen within 12 to 24 hours. If the illness progresses, descent is mandatory.
B. High-Altitude Pulmonary Edema: Mild HAPE presents with decreased exercise
performance, fatigue, dyspnea on exertion while moving uphill, a dry cough, and
localized inspiratory crackles on lung auscultation. In moderate to severe HAPE there is
marked weakness and fatigue, dyspnea on exertion walking on level ground, a cough of
scant sputum that progresses to frothy pink sputum, tachypnea, tachycardia, a gurgling
sensation in the chest, and bilateral inspiratory crackles on lung auscultation. Hypoxemia
is present as measured by an SaO2 % lower than normal for a given altitude.
Neurological symptoms and signs may also be present.
In a wilderness or mountaineering situation descent is the primary treatment.
Descending 2,000 to 4,000 feet (600 to 1,200 meters) often results in marked
improvement in symptoms, but descent should continue until medical care is reached or
symptoms resolve. Persons with HAPE should be accompanied by a healthy member of
the party and should not be left alone. Oxygen, if available, is a useful adjunct to descent
and improves arterial oxygenation, lowers pulmonary arterial pressure, and improves
symptoms. Oxygen may be used as the primary treatment without descent in settings
where supplemental oxygen is available around the clock and medical care is nearby
such as at ski resorts. Flow of oxygen should be sufficient to raise SaO2 to 90 % or
greater.
Adjuncts to oxygen and descent include nifedipine 10 mg orally or sublingual
every four hours or 30 or 60 mg sustained release once a day. An expiratory positive
airway pressure (EPAP) mask can be a temporizing measure. A portable hyperbaric bag
may be lifesaving when descent is impossible by providing a physiologic descent of
about 5000 feet when pressurized. Constant monitoring of a patient in a portable
hyperbaric bag is mandatory. Treatment continues until symptoms resolve or the weather
or climbing conditions permit the aided descent of the patient. One strategy for treatment
of HAPE in a portable hyperbaric bag is 50 minutes inside the bag followed by a 10
minute break every hour.
C. High Altitude Cerebral Edema: HACE is characterized by progressive neurological
deterioration with a headache and change in the level of consciousness associated with
