HIGH ALTITUDE PULMONARY EDEMA (HAPE)
By Dr. Clare O'Leary and Pat Falvey.

High altitude pulmonary edema (HAPE) occurs in unacclimatized individuals who are rapidly exposed to altitudes in excess of 8,000 ft. It accounts for most of the deaths from high-altitude illness. Similar to AMS, the incidence of HAPE is related to:

• Altitude gained
• Speed of ascent
• Sleeping altitude
• Individual susceptibility
• Exertion
• Cold is also a risk factor for HAPE

High altitude pulmonary edema commonly strikes the second night at a new altitude and rarely occurs after more than 4 days at a given altitude. Symptoms are often provoked by heavy physical exertion.
 
SYMPTOMS OF HAPE:

• Decreased performance
• Dry cough, which progresses to produce frothy sputum and eventually --blood-tinged sputum
• Breathlessness
• Chest discomfort
• Progressively increasing (resting) heart (>100bpm) and breathing --(>20bpm) rates
• 50% have associated AMS (fatigue, headache, loss of appetite, --insomnia)
• 14% have high altitude cerebral edema (HACE), (staggering, inability to --walk heel-to-toe)
• Fever is common

Confusion, hallucinations, drowsiness and coma represent severe pulmonary edema; death will occur in 6-12 hrs unless oxygen is given and/or the patient is descended promptly.
Persons with a prior history of HAPE have a risk of recurrence of approximately 60% on rapid ascent to high altitude.
 
PREVENTION OF HAPE:

• Ascend at a slow rate
• Avoid over-exertion

 
TREATMENT OF HAPE:

• Supplementary oxygen 4-6l/min for the first few hours (O2 saturation --should improve to >90% after 5mins), then reduce to 2-4l/min when --there is improvement
• Descent
• Portable hyperbaric chamber

If O2 sats do not improve to >90% or HACE is present, the patient
must be moved to a lower altitude.

Medication is only necessary if supplemental oxygen is unavailable or descent is impossible. Nifedipine 10mg orally initially, then 20-30mg of slow release formulation 12hrly is recommended. Dexamethasone is of no value in HAPE; use if there is associated HACE.

In those with recurrent HAPE or in those with HAPE at altitudes <2,500m, prophylactic nifedipine (20-30mg of slow release tablet) may be considered.