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Acute Mountain Sickness
Skiing vacations, mountain hikes, summit climbs and other high-altitude forms of recreation have always been popular activities. In recent years however, as more and more people have taken to flying around the globe in search of higher peaks and snowfields to conquer, there has been increasing cases of acute mountain sickness, one of the most common and preventable health hazards a visitor to the high altitudes will have to face.
What is Acute Mountain Sickness?
Acute mountain sickness, or AMS, is more commonly known as altitude sickness, and most commonly occurs at altitudes higher than 2500 metres. Its symptoms include headache, fatigue, shortness of breath, nausea, and poor appetite. Inability to sleep is also commonly reported.
The cause of AMS is fairly simple. Essentially, the human body is made to function at its best in the conditions you would find at sea level. The higher you go a mountain, the more extreme the conditions become and the harder your body has to work to maintain its normal functions. When climbing up a mountain, the main concern is the decreasing atmospheric pressure, which prevents the body from drawing enough oxygen from the air. The higher up you go, the harder it becomes to get the oxygen needed; the less oxygen the body gets; the less oxygen it gets, the harder it has to work, the less energy it has to pull in oxygen and so on and so forth in a rather nasty cycle.
Though that all sounds very dire, the reason why you can find entire civilizations living 10,000 metres above sea level is that the human body, if it is given enough time, can adapt to the new conditions. In days of yore, this wasn't a problem - anyone who wanted to go skiing on a mountain summit first had to hoof it up to the snowfield on their own two feet, which often took just enough time to let the body adjust to the changing environment. Today, what with airplanes, helicopters, cars and other modern conveniences, visitors can go from sea-level to mountain-top without bothering about the bit in between, giving their bodies no time to adjust to the new conditions. Even in this situation, the body is remarkably good at adapting and preserving itself, as long as it is given a little leeway to do so. It is only when people aren't aware of, or ignore, the symptoms of AMS that the problems really begin to start.
Who Gets AMS?
AMS is an equal-opportunity health hazard - it doesn't discriminate between genders, fitness level or how many times you've ascended. The most important factor is the rate of ascent, which will affect each individual differently. If that weren’t enough, factors such as distance traveled, the season, temperature and time of arrival also affect a person's risk of suffering AMS. Having said that, there are people who have a higher risk of suffering AMS:
How Do You Prevent AMS?
The simplest way to avoid AMS is to give your body a break and let it have time to adjust to the change in altitude. If you're taking a plane to a destination set at a higher altitude than you're used to, give yourself a day or so after landing to just relax before heading for the ski slopes. For recreational climbing trips, doctors recommend a gradual ascent, going no higher than 300 to 400 metres daily, with plenty of rest breaks.
Once you're at your destination, be sure to drink lots of water. The general rule of thumb is to consume twice your usual amount. It is also wise to limit the intake of alcohol and caffeine the first couple of days at altitude as they can cause dehydration. If you are on any form of medication, in particular painkillers or sleeping pills, be sure to check with the doctor to learn how it might affect you at altitude.
One of the more popular ways to prevent AMS is to take the drug, Acetazolamide, which also goes by the trade name Diamox. It is used to treat mild cases of both mountain sickness and altitude insomnia. The danger however is that some people may treat the drug as a substitute for proper acclimatization. There have been cases of people suffering cerebral or pulmonary edema while taking Diamox. Like all medications, it must be used with care and with medical supervision.
How is AMS Treated?
The golden rule for spotting AMS is: any illness at altitude is AMS unless proven otherwise. Even if you think it is 'just a slight headache,' stop - it just might not be. If you, or someone in your party, show any signs of illness, do not ascend further. This is extremely important, and bears repeating. Ascending with AMS almost inevitably leads to far more severe problems. If you cannot descend, then stay at the same altitude until the symptoms are completely gone. This may take anywhere from 24 to 48 hours.
The simplest and most effective treatment is to descend to a lower altitude. The moment the symptoms are recognized, the person should be escorted to a lower altitude. Delay can be fatal. A quick guideline is to take them down to the altitude at which they were able to function with no signs of AMS. If you're not sure what altitude that is, a descent of 500 - 1000 metres is a good start. A person with AMS should never be left alone, as they may not be able to descend with anything like their normal competence, or be able to recognize that they are getting sicker.
Though AMS is often quickly remedied, complications may arise. The most common is high altitude cerebral edema, (HACE), in which the brain is essentially swells and ceases to function properly. The most common sign of this condition is a change in the person's ability to think. This can range from a headache, to hallucinations, to psychotic behaviour. Another common sign is ataxia, or loss of coordination, similar to a drunk's attempt to walk in a straight line. Less common, but just as serious, is high altitude pulmonary edema (HAPE), which is caused by fluid build-up in the lungs. Symptoms include weakness, shortness of breath, even at rest, impending suffocation at night, and a persistent productive cough with white, watery, or frothy fluid. Both of these tend to strike at night and both are fatal in left untreated. As with AMS, the fastest and surest remedy is immediate descent - do not wait until morning!
Once at the lower altitude,
and given adequate medical attention and time to rest, recovery is usually
complete. Those suffering from HACE may still have the staggering 'drunk's
walk' for a few days after the descent, but it should eventually disappear.
Once recovery is complete, the ascent can begin again, with care and attention
paid to any further signs of AMS. |
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Article Information First published July 2005. This article is free for personal and commercial reproduction, with the following terms and conditions.
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