Acute Mountain Sickness
MCS AlexClimbThe influence of high altitude on the human body. Acclimatization and altitude sickness (Hypoxia)
What is "acute mountain sickness (AMS)"? The main causes, signs and possible consequences of AMS in the mountains.
This material does not pretend to any scientific scrupulousness, the author apologizes in advance for all inaccuracies made from a medical point of view. The information below is based on the personal experience of our guides working on high-altitude mountain routes without the use of oxygen.
Strictly speaking, there is not that much information about the exact causes and physiological processes occurring in the human body in conditions of lack of oxygen in the mountains. Studies conducted within the framework of scientific research of an applied nature, as a rule, had either military or space tasks, and weakly intersected with the specifics that people face while committing high-altitude ascents.
"Mountain sickness" - this is a common name for a complex of physiological disorders that occur in the human body while staying at high altitude. This phenomenon is not pathological, it is not a disease, in the true sense of the word. "Mountain sickness" is a functional disorder associated with the body's response to a lack of oxygen. The human body can adapt to this state, but it requires complying with certain conditions.
If these conditions are not fulfilled, a functional failure occurs, which can be expressed in a variety of painful manifestations. In most cases, when descending to the usual altitude horizon, all troubles caused by AMS pass without consequences.
Let's see what is the origin of "mountain sickness"?
With a sharp gain of altitude, the oxygen content, which is necessary for the normal functioning of our body, is significantly reduced. Our body can easily adapt and harmlessly stay in conditions of moderately rarefied air. But for this, it needs time to reconfigure functions and redistribute a limited amount of oxygen. This process is called acclimatization.
The altitude at which human body cannot acclimatize and exist for a long time is called the "death zone". In the moderate latitudes, this altitude is approximately 6500 meters above sea level. Up to this level, a normal and healthy human body can adapt to a long-term existence without serious risks for the health.
However, for many climbers, altitude problems begin much below the "death zone" - at generally moderate altitudes of 3000-4000 meters. Why that happens?
First, with a violation of the physiological acclimatization schedule - a sharp altitude gain, getting to the altitude with the help of mechanical means - a helicopter, a snowcat, a snowmobile, consequent decrease in physical activity after gaining altitude. All these factors can lead to unpleasant consequences, of which the most common are headache, nausea, vomiting, lack of sleep and appetite, and significant decrease of the life energy level.
However, in addition to these listed complications, problems that are more serious may arise due to “mountain sickness” which are associated with exacerbation of chronic diseases. The fact is that "acute mountain sickness" - hypoxia - does not have a specific set of symptoms. This is a general functional disorder, the course of which occurs more or less individually in each case. We can say that the lack of oxygen hits the body in the most vulnerable parts.
Sometimes, these hits can be extremely serious - there are many cases when the acute course of "mountain sickness" led to the development of diseases such as cerebral edema, pulmonary edema, acute pneumonia, stroke, etc. You can understand that the appearance of such diseases in the difficult conditions of high mountains, as a rule, proceeds quickly and often lead to the most serious consequences.
How can you predict "mountain sickness" and avoid its acute manifestations?
The answer is surprisingly very simple. There are just few simple rules.
The acclimatization schedule should be smooth, the altitude gain should be gradual, the physical loads should be moderate, and the rest should be sufficient.
Acclimatization routes, as a rule, begin at an altitude of no more than 2000 meters - this level, in the vast majority of cases, does not pose a danger even to people who go to the mountains for the first time. From this level, radial climbs are done with a gain of 700-900 meters, followed by a descent to the camp and a good rest in comfortable conditions.
After two or three days, you need to spend the night at an altitude of about 3000 meters - in the absence of pronounced health problems and signs of hypoxia, you can continue acclimatization for a kilometer higher. Generally, recognized signs of successful acclimatization are normal sleep and appetite. If, for example, at an altitude of 4000 meters a person can sleep, recover during sleep and fully digest food - this means that he can continue to climb and acclimatize for another 1000 meters up. And so on.
When forcing the acclimatization schedule, reducing the recovery time, doing excessive physical exertion, using mechanical means for transportation, the normal acclimatization process fails, which can lead to the consequences mentioned above.
The best way if not to avoid "mountain sickness", but at least significantly reduce the likelihood of serious consequences - is to apply the common sense and experience. You should never neglect the symptoms of altitude sickness or try to cure them staying at the same altitude, - these mistakes usually lead to the most disastrous consequences.
At the same time, you should not assume that staying at high altitude will be absolutely comfortable and will not cause any inconvenience to you in the first days. This is wrong. Staying in the mountains, adapting the body to difficult high-mountain conditions is a complex physiological and psychological process for which you need to prepare yourself in advance.
Being in the mountains is always associated with increased physical loads, extreme stress for the body. Therefore, in order for the process of acclimatization to proceed as least painfully as possible and not to turn into a dangerous to health form of "mountain sickness", one should regularly exercise, do not abuse fatty and high-calorie foods while staying in the mountains, refrain from alcohol and smoking...
But, since we all, to one degree or another, violate these ideal recommendations, we can only rely on our own reason, experience and care of our friends around us - this is the best protection and the most reliable shield against all unpleasant situations, not only in the mountains, but and in our normal daily life as well.
Author of texts and photos - Alex Trubachev
MCS EDIT 2023