High Altitude Health Advice
Typically
mountaineers ascend from low to higher altitudes and are thus exposed to
continuously increasing hypoxia. As the altitude increases, the barometric
pressure within the surrounding environment falls. This drop in barometric
pressure, and thus drop in the density of the air means that there are fewer
oxygen molecules in a given volume of air than there are at sea level. Therefore
with each breath, less oxygen is able to be taken in and utilised by the body. This
subsequent reduction in oxygen delivery coupled with various other confounding factors
can therefore induce health issues for an individual at altitude.
This page
will identify the health issues that are likely to arise on a trip to high
altitude (above 2,500m) and provide advice as to how these conditions may be
prevented and/or treated in order to maximise both the safety and the enjoyment
from any high altitude sojourn.
These pages offer advice and
guidelines that have been based on previous literature. These pages however
should not be taken as the only options and any individual travelling to
altitude should seek medical advice from an expert before doing so.
Acute effects of hypoxia; the initial
effects of altitude exposure
A number of
physiological responses occur when an individual is first exposed to altitude.
The awareness of these responses is important for the mountaineer or the
recreational climber;
·
An
increase in ventilation. i.e. the rate and depth of breathing
·
An
increase in both the heart rate (HR) and the cardiac output of an individual
·
Increased
diuresis
·
Increased
blood lactate
·
Greater
red blood cell (RBC) production (Approximately after seven days)
·
Increased
perception of effort
Acclimatisation
The acute
responses to hypoxia outlined above, indicate the fact that the human body is
an adaptive organism that has the ability to adjust to the changing environment
around it and that the acclimatisation of the body to altitude, albeit up to a
certain point, is possible. Acclimatisation is a term used to describe the slow
adaptation of the body to cope with the lower levels of oxygen at altitude and
should figure in the planning of all individuals preparing to ascend to high
altitude. If adequate time is allowed during a climb to high altitude, the
majority of healthy individuals will be able to function unhindered. This, in
turn will increase the chances of summiting.
When
travelling to high altitude sufficient acclimatisation is also imperative in
order to avoid altitude illnesses. The speed of the ascent and the
susceptibility of an individual are the two main determining factors culminating
in the risk of developing an altitude illness. When going too high too fast, the body is unable to adapt sufficiently
and life-threatening illnesses may be the consequence. Susceptibility to such illness
differs from person to person, however and an altitude that may evoke symptoms
in certain climbers may provoke no such effect in others. Therefore In a group
of climbers the acclimatisation process should always be tailored to ensure that
the health of the individual who is slowest to acclimatise is maintained.
So what is recommended?
·
Do
not rush the acclimatisation phase (It is now possible to start the
acclimatisation process prior to departure)
·
Do
not sleep at an altitude exceeding 300m higher than the previous night
·
If
possible schedule a rest day every 2-3 days
·
Ensure,
if climbing in a group, the process is tailored to the individual who is slowest
to acclimatise
·
Be
aware of the time course of AMS (below)
Acclimatisation to hypoxia is, as
already stated, possible up to a certain threshold. It is estimated that the
upper limit for the permanent acclimatisation of an individual is approximately
5,000m. Above which the process of permanent acclimatisation becomes impossible
as the body starts to deteriorate. Short term acclimatisation, however is
possible amongst healthy individuals to an altitude of approximately 6,500m.
Above this point (extreme altitude) the body will deteriorate linearly with
increasing altitude and supplementary oxygen will usually always have to be
administered.
Acute Mountain Sickness (AMS)
The
most common illness associated with travel to altitude is termed acute mountain
sickness (AMS). AMS develops in mountaineers ascending
to high altitudes who are un-acclimatised. The condition usually develops within
6-12 hours of reaching a critical altitude and peaks at approximately 24 hours.
Although some incidences of AMS have been reported at as low as 1000m the
condition is usually experienced at an altitude of approximately 3,000m and
above.
The incidence of AMS increases with
altitude, and hypoxia is the main causative factor for the onset of the
illness. When mountaineers ascend rapidly to 2,500 m, about 10% will suffer
from AMS, and when ascending to 4,500 m, the AMS incidence will exceed 60%.
Therefore an individual climbing Mount Kilimanjaro for example, which stands at
a height of 5,985m, should expect to develop at least some of the symptoms
associated with AMS and therefore take precautions for both the prevention and
treatment of such symptoms.
AMS is
characterised by;
·
Frontal
lobe headache
·
Nausea
·
Fatigue
·
Vomiting
·
Tiredness/
difficulty sleeping
·
Lack
of appetite
In more severe cases further symptoms
include;
·
Ataxia
(decreased co-ordination)
·
Decreased
mental status i.e. confusion, aggression
How to treat AMS
During slow ascents with multiple
overnight stays at altitude, an individual acclimatizes, and AMS can be avoided,
once again highlighting the importance of a well planned acclimatisation
schedule and illustrating how prevention is better than treatment. However,
often such symptoms, such as a headache, are inevitable at altitude with
approximately 96% of all people at high altitude suffering from the symptom.
Therefore it is of importance to know what can be done to combat such symptoms
at altitude.
It is also of importance to be aware
of the time frame of such altitude conditions in order to determine whether an
individual has truly passed the vulnerable stage of the illness and can
therefore continue with their ascent. This, however in some cases is difficult as
the development of symptoms can continue to worsen from anywhere between 12
hours and 3 days.
The occurrence of AMS does not necessarily
spell the end of a climb; it does however mean that certain measures should be
taken in order to prevent the development of AMS in to a more serious condition.
Such measures include;
·
Administration
of supplemental oxygen
·
Sufficient
fluid replacement
·
The
cessation of any further ascent for at least 1 day (or until symptoms are
reduced)
·
The
use of acetazolamide (Diamox)
·
The
use of Paracetamol/Ibuprofen in order to combat headaches
·
If
symptoms persist it is imperative individuals descend
General advice whilst at high altitude
·
Keep
an eye on fellow climbers
·
Be
honest regarding how you are feeling, do not lie about, or undersell any symptoms you may have
·
Be prepared before you leave
·
Make sure you know how to
prevent, identify and treat the illnesses that may arise
·
Remember that slow ascent is the
most important measure to prevent the onset of altitude illness
·
If you have any existing health
conditions prior to departure i.e. diabetes, asthma etc, ensure you see a
doctor or specialist to find out the risks your condition may pose to high
altitude travel and ensure you have
taken all precautions necessary
The use of
the drug acetazolamide has been mentioned a number of times. This drug, with
the trade name of Diamox, is used as prevention against the effects of AMS. The
drug works by speeding up the acclimatisation process and can also aid the
sleep condition of periodic breathing. Although the drug works to reduce the
effects of AMS it does not mask the symptoms and mountaineers should be aware
that individuals can still suffer from AMS as well as the more serious
conditions of HAPE and HACE whilst taking the drug. It is also important to be
aware that some people may be allergic to the drug which may cause the tingling
of the extremities; however this will cease when the taking of the drug has
stopped.
The use of a
pressure bag, or a Gamow bag as it is also known, has also been recommended. Although
these bags can save lives it is also important to be aware of the accompanying
problems that come with such equipment. Such problems include difficulty
communicating with an individual inside the bag and the subsequent difficulty
in monitoring their situation. Furthermore if dealing with an individual who
has lost consciousness a person will need to be inside in order to closely
monitor the condition of the ill individual. Moreover such bags can damage the
eardrums and in many cases recovery is often short lived. Nevertheless, as
already stated such a piece of equipment can save lives at high altitude and it
is essential for an individual planning on travelling to such an environment to
be aware of such equipment.
Further possible health problems at
altitude
·
Blocked
nose and sore throat
·
Sun
burn
·
Dehydration
·
Heat
stroke
·
Hypothermia/hyperthermia
·
Exhaustion
·
Diarrhoea
·
Constipation
A number of
health issues, big and small, are possible to occur when travelling to high
altitude and as already stated individuals should be aware of what the risks
are. This page has outlined the main and most serious illnesses and provided advice
as to how these illnesses can be prevented and treated. Prevention is the best treatment and if properly prepared there is
no reason why these conditions should spoil your climbing/ mountaineering
experience.
Good Luck!
References;
Burtscher, M. (2007). Arterial oxygen
saturation during ascending to altitude under various conditions: Lessons from
the field. Journal of Science and Medicine in Sport. 6, 535-537.
Burtscher, M., Brandstatter, E., Gatterer, H. (2007). Preacclimatisation
in simulated altitudes. Sleep Breath. 12 (2). 109-114.
Burtscher, M., Szubski, C., Faulhaber, M. (2007). Prediction of the
susceptibility to AMS at simulated altitude. Sleep Breath. 12 (2). 103-108.
Maggiorini, M., Melot, C., Pierre, S. Et al. (2001). High altitude
pulmonary edema is initially caused by an increase in capillary pressure. Circulation. 103 (16). 2078-83.
Roach, R.C., Hackett, P.H. (2001). Frontiers of hypoxia research: acute
mountain sickness.The Journal of Experimental Biology. 18. 3161-70.
Strote, J., Prutkin, J. (2006). High-altitude pulmonary edema presenting
18 hours after descent. Wilderness and Environmental Medicine. 17 (2). 137-9.
Tannheimer, M.A.J., Albertini, A., et al. (2009). Testing individual risk of acute mountain
sickness at greater altitudes. Military Medicine. 174 (4). 363-9.
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