Altitude

Just the Facts

The concentration (percentage) of oxygen in the air is the same at all altitudes.

The amount of oxygen available to the human body is determined by atmospheric pressure which decreases with altitude -- the air thins leaving fewer molecules of oxygen per breath.

Atmospheric pressure determines how much air is "pushed" into the lungs with each breath.

The atmospheric pressure at the summit of Mount Everest (29,028') is about a third that at sea level.

Heart beat rate, breathing rate, and the production of red blood cells, which carry oxygen throughout the body, increases as the body acclimates to high altitude allowing more oxygen to be "grabbed" from every breath.


Acute Mountain Sickness (AMS)

Often occurs around 8,000'

Symptoms:
 

  • Vomiting
     
  • Headeache that doesn't respond to usual medicine
     
  • Shortness of breath
     
  • Exhaustion that doesn't fade with rest
     

    This may be a warning sign for the onset of more serious altitude illness.

    Treatment is rest with further ascent recommended only after symptoms have ceased.


    Severe AMS

     

  • Altered balance or muscular coordination
     
  • Altered mental state
     
  • Extreme shortness of breath with almost any activity
     
  • Person is angry, combative, or incomprehensible

    Further ascent is not recommended unless there are options for easy and rapid descent should symptoms recur.


    HACE Symptoms

    Has occurred as low as 10,000'

     

  • Ataxia or loss of balance and muscle coordination
     
  • Decreased mental functioning
     
  • Severe headache
     
  • Nausea and vomiting
     
  • Hallucinations or stroke-like symptoms of impaired speech

    Coma and death may rapidly follow. The only treatment is immediate descent.


    HAPE Symptoms

    Rarely occurs below 8,000'

     

  • Extreme difficulty breathing and inability to catch one's breath
     
  • Very rapid pulse and breathing rate (over thirty breaths per minute)
     
  • Extreme exhaustion and difficulty with any exertion
     
  • Coughing which may progress to sounding bubbly as lungs fill with fluid
     
  • Fever and blue coloring, especially the lips and finger-nail beds

    Death can come on quickly. The only treatment is immediate descent.


    Acclimating

     

  • Climb as high as you want during the day, but raise sleeping altitude by no more that 1,000' a day.
     
  • Factor in a rest day every 3,000'.
     
  • Spend at least one night below 10,000' before ascending higher.
     
  • If you don't feel good, don't raise sleeping altitude until you feel better.
     
  • If you don't feel better at the current sleeping altitude, descend to below where you first felt sick.


    Facts taken from Stephen Bezrucha's "Altitude Sickness: Prevention and Treatment," with permission from The Mountaineers, Seattle, WA

    This article originally published at:  http://classic.mountainzone.com/everest/98/altitude.html

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