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Mayo Clinic Medical Science Blog

Archive for May 17th, 2012

High Altitude Pulmonary Edema

Posted on May 17th, 2012 by Admin

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.



Prelude to an Ascent

Posted on May 17th, 2012 by Admin

The North Face/National Geographic climbers are nearing the end of their wait. Talk about patience! The weather seems to be allowing a small window at the end of the "season" for some ascents. The Mayo expedition team members, now back in Minnesota, [see TV interview with Dr. Bryan Taylor] will be watching with great interest over the next week as the climb is set to begin on the 21st.  Before the researchers left for home, all the expedition members -- from Mayo, the North Face, National Geographic and Montana State University -- gathered for a final photo.