Essay: Part 2: Acclimatization Lee Meyers - Basecamp Wed, April 18, 2001 7:00AM
The human body's responds to going to moderate or high altitude goes through a process know as acclimatization. Acclimatization is a slow process, so going to altitude slowly prevents many problems. The British expeditions of the 1920's had no problems in the early stages as it took them about thirty days to travel to base camp at 17,000ft. Modern day expeditions to North side Mt. Everest base camp take as few as 3-4 days. Our expedition members spent 7-8 days to go from Kathmandu to the Rongbuk base camp, and therefore we did not experience any major problems of altitude sickness that some teams do.
Even with our "slow" trip up to Base camp, some team members experienced some of the signs of Acute Mountain Sickness (AMS), which include shortness of breath, headache, loss of appetite, nausea, sleeplessness, and malaise. These symptoms usually resolve without treatment within a couple of days at base camp.
Altitudes above 10,000 ft. will usually cause important changes in the human body leading to acclimatization and failure to undergo these changes can lead to serious problems. While the percent of oxygen in the air remains at 21%, no matter how high you ascend, because of the lower barometric pressure at altitude the air becomes thinner- there are fewer oxygen molecules in each breath.
The most important change at altitude immediately is that you breath faster, thereby getting more oxygen. There are also changes in blood pH and shifts in body fluids, which help deliver more oxygen to the bodies tissues and muscles. Over time, days to weeks, there are increases in the number of red blood cells and cellular enzymes so that muscles work more efficient.
Diamox is a drug, which some people use to help them acclimatize to altitude. We discourage the use of diamox on Mt Everest as it slows down the process of natural acclimatization. Diamox causes you to breath faster artificially. It also is a diuretic and can cause some degree of dehydration, which is not good at altitude. It can be used sometimes to help sleep at night, especially if a climber is having Cheyne-Stokes or periodic breathing pattern at night. As a general rule, we would not allow a climber using Diamox or having signs of AMS go higher on the mountain until better acclimatized.
Our climbers acclimatize by sleeping as high as the North Col, Camp IV 23,000ft., 2-3 nights or ABC 5-7 days before descending to Base camp to recover and regain their strength. Acclimatization would not occur by sleeping as high as Camp V (25,000 ft.) or Camp VI ( 27,000ft), as at these altitudes the body deteriorates from lack of oxygen, appetites are poor and sleep doubtful.
The highest known human settlement is a mining town in Chile at 19,000 ft. Spending long periods above 19,000 ft. makes for a weak and ineffective climber.