Tuesday, 16 October 2012

High altitude health advice

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

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!

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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