When trekking in the Himalayan there
is always a real danger of mild to serious problems
related to altitude. The complaints are collectively
known as acute mountain Sickness (AMS)
It is important that trekkers understand
that they will be affected to a greater or lesser extent
when they ascend to altitudes over about 3000 meters.
As you climb higher the atmospheric pressure falls and
the amount of available oxygen also falls. The body
will adjust to cope with this by altering the characteristics
of your blood in order to utilize better the lower oxygen
levels available to it. This process takes time and
can vary from individual to individual. Indeed, individuals
can experience different rates of acclimatization on
separate visits. So, having acclimatized well on a previous
visit is no guarantee of quick acclimatization subsequently.
The mechanics of acclimatization are not
well understood but it has been proved that a number
of factors have a positive effect. By far the most important
is regulating your rate of ascent when traveling in
excess of 3000 meters above sea level. As a general
rule you should not gain more than 400-500 meters a
day and have a rest day every fifth day. Maintaining
a good fluid intake and urine output has also been proved
to be effective in combating the effects of altitude.
The dry air of the mountains tends to dehydrate you
so an increased fluid intake is necessary. Try to drink
at least four liters of water a day. Prophylactic medication
should not be required to aid acclimatization unless
specifically prescribed by a physician skilled in the
treatment and prevention of altitude sickness. Fitness
may have some effect on speedy acclimatization but being
young and fit does not guarantee immunity. The only
age concern is for the very young who may not be able
to describe their symptoms to their parents. For this
reason it is unwise to take very young children to altitudes
above 3500-4000 meters. Symptoms of AMS may be mild
or severe and the victim can develop severe symptoms
very rapidly if the mild effects are ignored. The most
commonly reported complaints are:
- Headache that may respond to painkillers
but then returns
- Loss of appetite
- Swelling of the limbs.
- Difficulty in sleeping
- Irregular breathing
- Unusual weariness
Poor coordination and slurring of speech.
All or some of these symptoms may be present in mild
cases of AMS but they can rapidly worsen and become
dangerously debilitating. In particular, as the symptoms
worsen the victim will often become irrational and difficult
to reason with. Their ability to make sensible decisions
for themselves is invreasingly impaired and their companions
may be their only hope of survival. This is a compelling
reason for never trekking alone at altitude.
In the final stages of altitude sickness
serve problems start to appear which can rapidly lead
to loss of consciousness and death if untreated. Two
forms of AMS are generally recognized. One or both may
be present and either is extremely serious.
High Altitude Pulmonary Edema
This is caused by an accumulation of fluid
in the lungs. As the complaint progresses more and more
fluid builds up until the victim literally drowns. The
symptoms include difficulty breathing and rapid pulse
rate even at rest, coughing pink, frothy sputum and,
occasionally blueness around the lips.
High Altitude Cerebral Edema (HACE)
This is the most serious of the forms
of AMS, is caused by a build up of fluid around the
brain. The previously mentioned symptoms of mild. AMS
rapidly worsen, particularly the headache along with
slurring of speech and ultimately unconsciousness and
death. The advance of the problem can be very rapid
and death can occur in twelve hours if treatment is
Treatment of AMS
There is one simple treatment for AMS
and that is DESCENT, stopping the ascent for a day can
treat very mild symptoms of AMS. After this the symptoms
will often disappear and the trek can be resumed. If
the symptoms are such that the victim is obviously suffering
then descent, to point at least 500 meters lower, must
be commenced. The descent should not be delayed even
if it means going down in the dark, if the victim is
still able to walk it makes the treatment easier but
if necessary they may have to be carried either by a
companion or by horse or yak.
If it is available, bottled oxygen can
help the patient but descent should still not be delayed.
A portable hyperbolic chamber (Gomow bag of PAC bag),
if available can be used to raise the atmospheric pressure
experienced by the victim and can temporarily ease the
symptoms of AMS. The relief will only be temporary and
descent is still necessary.
On the Everest Base Camp route and
on the Annapurna Circuit there are clinics, operated
by the Himalayan Rescue Association that specializes
in treating trekker’s health problems particularly
AMS. In the Everest region the clinic is at Pheriche
while the one on the Annapurna Circuit is at Manang.
Skilled western doctors who can help treat and advise
victims of AMS staff both of these clinics. It must
be remembered that these clinics are only open during
the main trekking seasons of 1st October to 14th December
and 7th March to 20th May.