Advancing the Science

Mayo Clinic Medical Science Blog – an eclectic collection of research- and research education-related stories: feature stories, mini news bites, learning opportunities, profiles and more from Mayo Clinic.

May 17, 2012

High Altitude Pulmonary Edema


One in a series of articles on the science of the expedition, this by Doug Summerfield, M.D. and Bryan Taylor, Ph.D.

One interesting, and potentially very dangerous, component of Mountain Sickness is the development of High Altitude Pulmonary Edema (HAPE). HAPE occurs in ~6% of those who travel to altitudes above 14,000 feet and is likely a consequence of a hypoxia-induced increase in blood pressure within the lungs. Factors that may increase the risk of developing HAPE include rapid ascent to altitude, excessive exercise, respiratory infection, and genetic variations. Symptoms include shortness of breath, decreased exercise tolerance, and a dry cough.  In more severe cases pink frothy sputum can occur.  Symptoms typically begin within 48-72 hours of a rapid ascent but it is rare to develop HAPE after remaining at a given altitude for more than five days.

See the HAPE graphic.

HAPE is not just an important topic for the occasional researcher who is either intrigued enough or crazy enough to sojourn into the extremes of the Himalayas.  Although at much lower altitudes, every year cases of HAPE occur in the American Rockies (~8,000 ft) when unsuspecting vacationers become at risk for this potentially life threatening condition.  The absolute number of cases is unknown but the incidence at ski resorts is thought to be between  0.01-0.1%.

You can minimize your chances of developing this condition by slowly acclimatizing.  A good rule of thumb is to not increase your elevation by more than 2,000 feet a day.  Also sleeping at an altitude below where you spend your daily activities has lead to the adage of “work high sleep low” and is another good strategy.  Medications such as Acetazolamide can be taken prophylacticly to minimize occurrence of HAPE. If the condition does develop, “rescue” medications such as dexamethasone, nifedipine, and sildenefil may help stabilize a patient, but decent is the only definitive treatment.



Tags: altitude research, altitude sickness, Innovations, Mount Everest, News, People, Progress Updates, pulmonary edema

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