Altitude
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The elevation of the land/air anything above 1200mts would mean high altitude. Medically high altitude
would mean changes in the human physiology. With the change in the altitude human body reaction to the
change is different.
People living at lower altitude are used to higher density of oxygen molecules in the air. As the altitude
increase the atmospheric pressure of the air decreases thus reducing the level of oxygen. People living in
the higher altitudes have higher level of hemoglobin (red blood cells) in their blood which helps to take in
more oxygen supply while the people in the lower altitude have lesser hemoglobin concentration.
It is found out that the oxygen on the summit of Mt. Everest is only one third of that found at the sea level.
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Acclimatisation
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As we go to higher altitude our body undergoes different physiological changes. The changes which
occurs and helps our body to function normally even under lesser oxygen supply is acclimatization. As
our body acclimatizes it produces more number of hemoglobin thus increasing the oxygen supply to the
body. It take a few days to acclimatize to any particular altitude.
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Acute Mountain Sickness (AMS)
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Rapid accent to higher altitude can lead to Acute Mountain Sickness. Above 2000mts about 18% -70%
acquire mild AMS. Both males and females are similarly effected by AMS. AMS can occur to any age
group. Even a young healthy athlete can suffer from AMS. Most of the cases that have been instanced
were young men who appeared perfectly sound. Young, strong and healthy men may be completely
overcome. There is an increase in breathing frequency when one is exposed to lower oxygen
environment. This natural response is known as the hypoxic ventilatory response (HVR) and there is
some evidence to suggest that people with a low HVR are more liable to develop AMS.
However, the well-known mountaineers Messner and Habeler, who were the first ever to climb Everest
without supplementary oxygen, both had low HVR's and were interestingly not susceptible to AMS.
This makes it difficult to determine if you will suffer from AMS or not. Recent experiments conducted on
Mount Mc Kinley have revealed that subjects with a lower oxygen saturation develop AMS. EEG activity also
provides a potential predicting tool, although not yet fully established. Psychologists have also
examined methods of predicting susceptibility and have found that highly anxious individuals are more
sensitive to developing AMS.
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Symptoms of AMS:
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Headache
Fatigue
Nausea
Vomiting
Loss of appetite
Dizziness
Irritability
Sleeplessness
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Prevention of AMS
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The golden rule t o prevent AMS is to make gradual climb t hat our body has enough time for
acclimatization. Often lack of time and bad weather make people forget this rule but as far as possible
one should make deliberate slow accent to prevent AMS. If a trekker experiences any one of the above
symptoms one should immediately descend to lower altitude where one will feel much better.
Drugs like Diamox is used by most cli mbers/trekkers to prevent AMS. Diamox stimulates more breathing
thus taking in more oxygen supply. Like all drugs diamox does have side affects. Climbers should
consult their physicians before taking this drug.
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