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Mayo Clinic Medical Science Blog


Admin (@hinadmin) published a blog post · May 21st, 2012

What is the Death Zone?

Another in our series on the science of the expedition, Dr. Jim McEachen, Mayo Clinic aerospace medicine fellow provides background [Editor's note: this was written before the most recent deaths] 

In 1998, the popular PBS series Nova reported an ominous piece of data.  For every six successful summits on Everest, one person will die.  The show was following up on a tragic event that occurred two years prior. In one day, eight climbers died in the so-called ‘death zone’ on Everest.  The term ‘death zone’ is often used in reference to an altitude above 26,000 feet beyond which many researchers believe human life can no longer adequately acclimatize on its own to.  At 17,600 feet (Base Camp), the partial pressure of oxygen (pO2) is approximately half of its value at sea level.  At 29,000 feet (Everest Summit), the pO2 level decreases to approximately one third of its sea-level value. The ability of individuals to survive in such extreme conditions is a reflection of both their short and long term hypoxic compensatory mechanisms.  As an aside, the validity of the term ‘death zone’ does remain in dispute among some researchers who note select cohorts of individuals have survived for extended periods of time under analogous extreme hypoxic conditions.

Extreme hypoxic states are not limited to the mountainside.  They are also a matter of significant concern to both the airline and space industries.  For example, fighter and reconnaissance aircraft which can fly in excess of 50,000 feet must incorporate specialized environmental control systems and life support equipment to ensure the ability of pilots and aircrew to function under such extreme conditions.  Of particular interest, above Armstrong’s Line (63,000 feet) exposed bodily liquids could actually boil in the absence of protective life support equipment.  Such challenges do not diminish our desire to explore, but rather provide the basis for understanding and future innovation.  And so we climb further…

 

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