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Acclimatization capability
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Unlike Tibetans and Nepalese, who through the centuries have adapted to great altitudes, our permanence in those places can only be temporary. Even aboriginal people from South America settled in the Altiplano high plains, as the Quechua and Aymara, haven’t yet adapted entirely. A chronic variant of altitude sickness make some of them move to lower areas. Beginning at 5300 m performance diminishes continuously that sooner or later leads to death by exhaustion.
Beware of altimeters
Altimeters that show altitude by measuring atmospheric pressure must be constantly adjusted. Practical tests done with different altimeter clocks demonstrated that, for each 1000 m of ascent, they show between 50 and 80 m less. Due to this, you could be lead to believe you are camping at 4700 m, but in reality you are situated over 5000 m. This difference can mean drastic consequences at that altitude. Because air is compressible, atmospheric pressure adopts a curved form as altitude increases. However, altimeters function in a lineal way, so even the best models show differences in altitude.
Adaptation mechanisms
If there was no adaptation mechanism of the body we could only climb as far as 5 000 m. The most important altitude adaptation mechanisms are, first of all, the increase in the frequency and depth of breathing (hyperventilation), which has a relative importance of 60%; the raise in red cells production improves adaptation in 20%; and a higher efficiency of the cells in the use of oxygen make up the last 20%. The breathing frequency, in normal conditions, is controlled by the carbon dioxide pressure in blood, but as altitude increases, it doesn’t raise in the same measure. So the body regulates breathing by saturating with oxygen the blood in the arteries. Hyperventilation leads to the exhalation of carbon dioxide and so it increases the oxygen content in pulmonary alveoli.
Cheyne-Stoke breathing
At night it would seem that we sometimes partially forget breathing. Suddenly, we realize this and we start breathing fast and deep, as a diver surfacing. When we sleep, such pauses in breathing are generally perceptible only to our tent mates. In most cases, these respiratory difficulties persist at the same altitude only for the firsts few nights.
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