What is the reason for the reduction in height

Acclimatization: How to do it right

The offer on the Internet is great. Guided tours to countless peaks can be booked. A four-day Monte Rosa tour begins by taking the mountain railway to over 3800 meters. You can get there for just under 2000 euros. Without good preparation and the necessary physical condition, such a project can quickly become a nightmare.

Projects in the Himalayas are even more dangerous. The approach to Everest base camp at almost 5400 meters can be shortened significantly by air and helicopter.

"These types of offers and their implementation, often far removed from any rules of ascent, are certainly one of the reasons for altitude sickness to occur today," explains Dr. Armin Berner, Senior Consultant in the Department of Anesthesia and Operative Intensive Care Medicine at the Garmisch-Partenkirchen Clinic.

Prophylaxis with side effects

"In addition, there is the sometimes hair-raising prophylactic medication recommended by dubious organizers in these projects," he warns of the common practice. An example: Some organizers recommend taking ASS 500 (short for Acetylsalicylic acid 500 mg) to prevent symptoms such as headaches. "This harbors two very obvious dangers," explains Berner.

"On the one hand, it disguises a possibly important alarm signal, namely the appearance of the first symptoms of altitude sickness, on the other hand, ASA has blood-thinning properties. In the event of a fall, this can lead to persistent heavy bleeding and thus entail completely different dangers. Actually white but every somewhat experienced mountaineer how to handle the ascent in a sensible way, "says Berner.

But theory and practice are often far apart, especially when altitude sickness occurs. Achieving the goal at any price is unfortunately more and more in the foreground.

Rules of promotion

  • not too high too fast

  • Walking prevents quick ascent

  • don't go too fast (pulse control)

  • not to carry too much (loads)

  • Sleeping height below the maximum daytime height (go high - sleep down)

  • drink a lot

  • 10 percent drop in performance per 1000 meters

  • The first symptoms can appear from 2000 meters above sea level.

Two-day phenomenon

Altitude sickness can occur in different degrees. A mild altitude sickness that starts in a few hours to a day is primarily expressed as a headache.

In addition, there are weakness, dizziness, loss of appetite, nausea and sleep disorders. "Performance and concentration levels decrease and the risk of accidents increases", summarizes Berner.

With the heavier forms, you have to choose between the so-called High altitude cerebral edema, a severe form of acute altitude sickness, and the High elevation pulmonary edema can be distinguished. They often do not appear on the first day after the onset of symptoms, but things get serious on the second night at a new sleep level.

If the severe forms are not correctly identified and treated, they are fatal in up to 40 percent of cases.

In danger: lungs and brain

The physiological response to the lack of oxygen is an increase in breathing and heart rate and is part of the acclimatization process. It can last for several days. A decrease in the increased heart rate is a sign of successful altitude adaptation, the so-called altitude tolerance. It is very different from person to person.

If you continue to climb to the next level, this process starts all over again. This adaptation works up to 5500 meters; permanent residence above this is not possible. Not only the absolute height, but also the way of ascent determine the adjustment options. It is always unfavorable if you climb too high too quickly.

The High elevation pulmonary edema occurs between an altitude of 2000 and 6000 meters and is noticeable by a rapid drop in performance with a previously inconspicuous course or slight shortness of breath with a dry cough.

Due to the low oxygen partial pressure in the atmosphere, i.e. little oxygen in the ambient air in relation to nitrogen, there is an increase in pressure in the pulmonary circulation (so-called hypoxic pulmonary vasoconstriction, HPV) with fluid escaping from the blood vessel system and fluid storage in the lungs.

"This makes breathing more difficult and also massively hampers the necessary gas exchange," says Berner, describing the effects. The body counteracts this reaction by increasing breathing, known as hyperventilation. The HPV is made more difficult or even impossible by alcohol or sleep-inducing drugs.

"As a result of these influences, the brain can no longer adequately react to the changed conditions and the result is a potentially life-threatening situation," warns Berner.

When acute altitude sickness is manifested in the brain, those affected are usually noticeable at first due to changes in personality. A key symptom of the transition from a rather harmless altitude sickness to the absolutely life-threatening form of altitude cerebral edema is gait insecurity, medical ataxia.

In addition, there are severe, drug-resistant headaches, nausea with vomiting, photophobia, fever, impaired consciousness up to coma and ultimately death in almost half of the cases. The cause of this is also a fluid retention, but in the brain.

While acute altitude sickness can occur in the entire Alpine region, high-altitude pulmonary edema usually only occurs in the western Alps, when trekking and high-altitude mountaineering. High altitude cerebral edema is very rare in the Alpine region due to the relatively low altitude.


  • Following simple climbing rules and rules of conduct would prevent a large proportion of altitude sickness.

  • All forms of altitude sickness are due to the lower oxygen partial pressure at altitude.

  • Severe forms are high altitude pulmonary edema and high altitude brain edema.

  • Altitude sickness usually begins with a headache, nausea or a drop in performance.

  • Drug prophylaxis can mask the important warning symptoms and thus pose a great danger. Exceptions are rescue operations or a known disposition.

  • Important cornerstones of therapy for altitude sickness are: oxygen administration, reducing altitude and increasing pressure.

  • High altitude pulmonary edema symptoms are often well managed by leaving altitude, giving oxygen, and the drug nifedipine.

  • Therapy for high altitude cerebral edema is more difficult.

  • If used sensibly, preventive altitude training can make an important contribution to the success of a project.


The following applies to the therapy of any type of altitude sickness: increase oxygen supply, reduce altitude and increase pressure. If one of these parameters is given, there is rapid improvement.

"After a ten-minute helicopter flight into the valley, a patient with the most severe symptoms of high altitude lung edema can breathe normally again on arrival," says Berner, describing his experience as a mountain emergency doctor on many rescue operations in the Western Alps.

"But it becomes dangerous if you can't get away from the top," he continues. Only one hut in the Alpine region has an inflatable pressure chamber, which makes it possible to expose the sick to a higher pressure.

With the mild form of altitude sickness one can on Ibuprofen To fall back on. "As long as that works well, it is not yet dramatic." In that case, however, it is not allowed to rise higher. As a result, the drug disguises important warning signals.

The therapy of the brain-related form of altitude sickness, however, is not so easy. Just leaving the altitude does not immediately bring a noticeable improvement. Drug therapy becomes unavoidable. "We use cortisone and oxygen for this," explains Berner.

Common sense is the best prevention

Many cases of altitude sickness could be caused by the Compliance with the basic rules and can be prevented with a few little tips on how to behave. You can start with the speed of the ascent, so "not too high too fast". The best way to do this is by walking.

A too rapid ascent, such as by helicopter or mountain railway, is unfavorable. Preparing your physique before a big tour is beneficial. On the one hand, a good average endurance is a prerequisite for a successful mountain tour at greater heights.

On the other hand, your own physical condition can be checked in advance and the tour plan can be coordinated in a meaningful way. Any well-trained year-round mountaineer can climb high mountains. However, top sporting performance in the valley is no guarantee of success at altitude. But of course it is also possible to prepare for higher peaks through training tours. "Altitude training before tours is a must!" Emphasizes Berner.

Not least to get to know your body and how it reacts to a lack of oxygen. If you have experienced altitude sickness on previous tours, there is an increased risk of having problems with it again. The following rule of thumb applies to overnight stays: Sleeping height below the maximum daytime height.

This means that you should not set up your bivouac at the highest point of the day, but definitely below it. "For the development of altitude sickness, it is not the daytime height that is decisive, but the sleeping height," summarizes Berner. Experts say go high, sleep down.

Problem hydration

The loss of fluid is a risk factor for the development of altitude sickness that should not be underestimated. Because drinks have to be carried by yourself when climbing high altitude, the amount you can take with you is automatically limited. However, it is precisely here that there is a higher fluid requirement.

"The air is cold and, above all, dry. We lose a lot of fluid through exhalation. Furthermore, a lot of fluid is naturally given off through sweating during physical exertion." All in all, it is probably five to ten liters that you need in fluid per day.

"A lot that you can't carry in addition." At high altitudes you have to melt snow anyway, at lower altitudes there may be water available. However, this should be boiled in most cases because of the risk of infection.

Sleep high in training

The 4000m peaks of the Alps are perfect for being used as a training tour for higher mountains. The interval between the end of training and the actual ascent should not be greater than seven days. The sleeping height is also important again.

"When exercising, you can lie higher than the rest of the sleeping height at home." This enables the body to acclimate, i.e. to adapt to altitude over the long term.

While trekking tours cause more altitude problems than individual mountaineers due to group dynamic processes and poor preparation of the participants, the risk of dying while climbing has decreased massively in the last thirty years. Certain providers, especially when it comes to expedition trips, are very careful to organize tours in a sensible way and to use the available aids and resources in a healthy manner.

But the danger cannot be dismissed out of hand, especially with inexperienced small expeditions. And the trend "faster and faster, further and further" naturally also harbors additional risks.

Text by Justus K├Ânig


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