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Q-Acclimatisation and High Altitude and its related problems to human bodies … OR “Why we have to climb to higher camps and back down several times?”

A- This subject can be expanded into a BOOK (yes, I am not kidding) and medical journals have been published on this subject. I will try to explain things in laymen terms.

In this discussion, any elevation higher than 2,500m (10,000 feet) is deemed high altitude.

The human body is designed to function at its best at sea level (0 meters) when the air pressure is measured at 1 atmosphere. This is because the hemaglobin (the reddish stuff in red blood cells) is saturated with oxygen (nearly 100%) at that air pressure. Oxygen is required by the brain, body organs, etc., and is needed for energy conversion from food you eat into glucose that the body can use.

As you go higher, the air pressure drops and so does the amount of available oxygen. At 5,000m (height of Everest Basecamp), the amount of oxygen is only half that of sea level’s availability. At 8,848m (summit of Mt Everest), only one third is available. When the amount of oxygen pressure drops, the human body tries to compensate. In a process known as acclimatisation, the body compensates for the lack of oxygen. Additional red blood cells are manufactured, the heart beats faster, non essential body functions are shut down (temporarily), and you breathe harder and more frequently. BUT, acclimatisation cannot take place immediately – in fact, it take place over a period of days or even weeks. Hence, when you first arrive at high altitudes, you have to take things easy. Even normal chores like walking is tiring.

Most climbers and high altitude trekkers follow the “golden rule” – Trek / Climb High, Sleep Low. For high altitude climbers like those attempting Mt Everest, the way to acclimatise is to stay a few days at Basecamp, climb up to a higher camp (slowly), stay there for 1 night initially, then return to Basecamp. This process is then repeated a few times, each time, you extend the time spent at higher altitudes to let the body “get used” to the oxygen level there. Once you are used to that altitude, you then repeat the process with a camp placed at higher elevations. Remember – you cannot rush this process (and this explains why we need to spend weeks at times acclimatising before attempting to climb a high peak).

However, more insidious and serious medical problems might develop in individuals who attempt to go up too fast. The two most common symptoms are HAPE and HACE (High Altitude Pulmonary Edema and High Altitude Celebral Edema). Both are life threathening and must be treated immediately. In fact, we saw 3 cases of them in the past 1.5 months here at Basecamp.

At extreme altitudes (above 7,500m), breathing bottled oxygen becomes almost mandatory for 99% of the climbers. This is because, at that height, available oxygen becomes so low you can hardly function without supplementary oxygen. Sleeping becomes very difficult, digesting food is non functioning (because the digestive system is non-essential to life), and you get hosts of other problems without additional oxygen.

Finally, at the “death zone”, 8,000m and higher, no human body can acclimatise at that height and staying longer than necessary will result in deterioration of body functions and ultimately, death.

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