Altitude sickness (AMS) is a serious medical condition brought on by
travelling too quickly to altitude, and/or performing physical exercise at
altitude when unacclimatised.
Tolerance to altitude varies greatly amongst individuals, but a fit person
who does not go too fast will not strain their cardiovascular system as much as
an unfit person for the same amount of exercise and will therefore be at a lower
risk of developing AMS. Even a very fit person however is still very likely to
develop AMS if they trek to altitudes above 3500m without some days spent
acclimatising or they walk too quickly.
Altitude sickness can occur in some people as low as 8,000 feet (2,400 metres),
but serious symptoms do not usually occur until over 12,000 feet (3,700m). AMS
is brought on by changes in the body caused by the reduction in air pressure at
altitude. At 5000m the air pressure is reduced to 55% of that at sea level and
at 6000m it is down to 49%.
This drop in pressure has three major effects.
Drop in oxygen saturation
With less actual air in each breath the amount of oxygen in the blood
reduces. Mild reductions in oxygen saturation will cause you to feel breathless
and tired. Bigger falls can impair mental functions and have serious adverse
effects. Below is a graph which shows the normal reduction in oxygen saturation
levels that occur at altitude.
If your oxygen saturation drops below 80% we consider this is serious and if
it drops below 75% you will be asked to descend.
As a result of the reduction in air pressure, fluid from the brain leaks into
the air cavities between the skull and the brain. This starts off by causing
mild headaches but if continues leads to pressure on the brain, complete
disorientation and eventually coma and death. The onset of cerebral oedema can
be very quick.
effect on the lungs is caused by the reduced air pressure inside the lungs which
allows fluid from the blood to pass through into the lung itself. This produces
symptoms like pneumonia. This is particularly a concern when sleeping.
It is a
mistake to think that AMS is the result of a gradual worsening of mild altitude
symptoms such as breathlessness and headache. AMS is in fact a sudden and
dramatic onset of symptoms and leaves the person hardly able to walk or look
of Altitude Mountain Sickness (AMS)
are a primary symptom used to diagnose altitude sickness, although a headache is
often a symptom of dehydration and can be confused with symptoms of AMS. You
must drink a minimum of 3 litres of water during the day to prevent dehydration
(see further information below).
occurring at an altitude above 2,400 metres (8,000 feet) with any one or more of
the following symptoms, can indicate some degree of altitude sickness and should
always be reported to your guide. General symptoms of AMS can include:
symptoms of High Altitude Cerebral Oedema (HACE)
symptoms of High Altitude Pulmonary Oedema (HAPE)
should be aware that HAPE can occur without any of the other signs of AMS.
Characteristic symptoms are:
type of AMS you might suffer from the treatment is the same:immediate descent by
over 1000m or until symptoms abate.
guides have any doubts about your health and believes that continuing to ascend
would be dangerous then they will insist that you descend to ensure your
safety. Before making this decision your guide will follow the following
Measure your oxygen saturation levels, if they are below 80%, then you will
be retested every 30 minutes for 2 hours. If your oxygen saturation does
not get above 75% then immediate descent is mandatory. If it rises above
75% then you will be allowed to continue but will be monitored very
closely. If your condition deteriorates during the ascent then you should
immediately notify your guide and you must descend immediately.
Evaluation of your Lake Louise Score, if it is between 6 – 8 then the guide
will make an assessment based on this score, your oxygen saturation and
pulse rate and your general well-being to decide whether you can continue.
If you are allowed to continue then you will be monitored closely during the
ascent but must also monitor your own condition and if you or the guide
notice a deterioration then you must descend.
your Lake Louise Score is above 8 then you must descend.
high sleep low:
As we go higher up we encourage everyone to do a short walk after arriving at
camp each day to go to a slightly higher altitude and to rest there for half an
rush: Walk slowly!
You need to keep your breathing rate down to that at which you can still
maintain a conversation. If you are breathing too hard to do this slow down: if
you work your heart and lungs hard the risk of illness increases dramatically.
drink and then drink some more:
Being properly hydrated massively benefits acclimatization and you simply cannot
drink too much (a minimum of 3 litres should be drunk each day even if you are
not thirsty!). If your pee is yellow you are not drinking enough. Symptoms of
dehydration can be similar to those of HACE so keeping hydrated is very
important so as not to confuse the two.
There has been a lot of research on diamox (which you can find by googling) that
shows is that it has been reasonably well proven to be helpful in avoiding AMS.
We take it ourselves when climbing Kilimanjaro. It is though a prescription drug
and some GP's will not prescribe it. You must therefore take your own medical
some controversy about Diamox, which is why some doctors will not prescribe it,
because some people thought that if they were taking it they could ignore
serious symptoms and this had fatal consequences. The key thing is that if you
get symptoms and you are taking diamox that is because the drug is not being
effective and YOU SHOULD GO DOWN!
to be taken prophylactically, i.e. before you start climbing to prevent altitude
sickness not when you are climbing and have symptoms. The recommended dose is
between 125 milligrams (mg) to 500 mg per day, starting a few days before going
to the higher altitude. If you are going to take Diamox then we would recommend
you take half a 250mg tablet morning and night. It is particularly recommended
for those ascending from sea level to 3000 meters (9800 feet) in one day, which
is typical of a Kilimanjaro trek.
If you do
take it you must always remember Diamox is not an absolute fix for acute
mountain sickness . For the avoidance of doubt diamox speeds up part of the
acclimatization process which in turn can help to prevent symptoms. If however,
symptoms do develop and deteriorate YOU MUST STILL GO DOWN.
Common side effects of using Diamox include numbness and tingling in the fingers
and toes. By far the worst effect is that it makes all fizzy drinks including
beer taste awful. Fortunately if you stop taking it after summit day by the time
you get to the bottom your taste buds will have recovered. You will also
experience more frequent peeing if you take Diamox and with drinking all the
time the combined effect can be really amazing : don't forget a pee bottle when