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Altitude Sickness
Altitude sickness, often known as Acute Mountain
Sickness (AMS) is a particularly important medical
consideration while trekking in Nepal. Altitude
sickness means the effect of altitude on those who ascend too rapidly to
elevations above 3000 meters. The initial symptoms of AMS are as follows:
·
Nausea, vomiting
·
Loss of appetite
·
Insomnia/sleeplessness
·
Persistent headache
·
Dizziness, light headedness, confusion
·
Disorientation, drunken gait
·
Weakness, fatigue, lassitude, heavy legs
·
Slight swelling of hands and face
·
Breathlessness and Breathing irregularity
·
Reduced urine output
These symptoms are to be
taken very seriously. In case of an appearance of any of the above symptoms any
further ascent should be avoided; otherwise more serious, even life-threatening
problems can occur. The only cure for Altitude Sickness is to descend to lower
elevations immediately. Acclimatization by ascending to no more than 300 to 500
meters per day above 3000 meters, and the proper amount of rest and rehydration
are the best methods for prevention of AMS.
If you follow the simple
advice of our trained guides, you won’t have to worry about complications from
mountain sickness. We design our tours to ensure clients are ready for high
altitude, and arrange alternative itineraries for those at risk where possible.
What is an Altitude Sickness?
Altitude is defined on the
following scale for the purpose of Nepal trekking: Normal (8,000 - 12,000 feet
[2,438 - 3,658 meters]), High (12,000 - 18,000 feet [3,658 - 5,487 meters]), and
Higher altitude (18,000+ feet [5,500+ meters]). Since few people have been to
such altitudes, it is hard to know who may be affected. There are no
specific factors such as age, sex, or physical condition that correlate with
susceptibility to altitude sickness. Some people get it and some people don't,
and some people are more susceptible than others. Most people can go up to 8,000
feet (2,438 meters) with minimal effect. If you haven't been to high altitude
before, it's important to be cautious. If you have been at that altitude before
with no problem, you can probably return to that altitude without problems as
long as you are properly acclimatized.
What Causes Altitude Illnesses?
The concentration of oxygen
at sea level is about 21% and the barometric pressure averages 760 mmHg. As
altitude increases, the concentration remains the same but the number of oxygen
molecules per breath is reduced. At 12,000 feet (3,658 meters) the barometric
pressure is only 483 mmHg, so there are roughly 40% fewer oxygen molecules per
breath. In order to properly oxygenate the body, your breathing rate (even while
at rest) has to increase. This extra ventilation increases the oxygen content in
the blood, but not to sea level concentrations. Since the amount of oxygen
required for activity is the same, the body must adjust to having less oxygen.
In addition, for reasons not entirely understood, high altitude and lower air
pressure causes fluid to leak from the capillaries which can cause fluid
build-up in both the lungs and the brain. Continuing to higher altitudes without
proper acclimatization can lead to potentially serious, even life-threatening
illnesses.
Acclimatization
The major cause of altitude
illnesses is going too high too fast. Given time, your body can adapt to the
decrease in oxygen molecules at a specific altitude. This process is known as
acclimatization and generally takes 1-3 days at that altitude. For example, if
you hike to 10,000 feet (3,048 meters), and spend several days at that altitude,
your body acclimatizes to 10,000 feet (3,048 meters). If you climb to 12,000
feet (3,658 meters), your body has to acclimatize once again. A number of
changes take place in the body to allow it to operate with decreased oxygen,
they are:
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The depth of respiration increases.
·
Pressure in pulmonary arteries is increased,
"forcing" blood into portions of the lung which are normally not used during sea
level breathing.
·
The body produces more red blood cells to carry
oxygen,
·
The body produces more of a particular enzyme
that facilitates
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the release of oxygen from hemoglobin to the
body tissues.
Suggested
Altitude Sickness information:
http://www.treksafe.com.au/medical/altitude_illness.htm
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