Mountain sickness is no joke! Why is it hard to breathe in the mountains

Everyone knows that the mountain climate at moderate altitudes (in the middle mountains) is extremely beneficial for health. In the mountains, people get sick less and live longer, recover faster from illnesses and have a more complete rest. This is confirmed by the abundance of mountain resorts, sanatoriums and boarding houses for recreation in the mountains. Not everyone, however, understands quite clearly why the mountains have such a beneficial effect on the body.

Speaking about clean air, strong ultraviolet radiation, qualitatively different food and water, they usually lose sight of the main acting factor - a reduced oxygen content in the air, meanwhile, this is what has a very powerful and versatile positive effect on the body. There are a fairly large number of ecologically clean resort areas on the plain, but none of them has such a beneficial effect on the body as the middle mountains. The most important feature of the mountain climate is rarefied air with low oxygen content.

Many thousands of years ago, yogis noticed the healing and restorative effect of rarefied mountain air. Life, however, is not in full swing in the mountains. For most people, both before and now, even a short trip to the mountains is a great difficulty and is associated with large material costs. Many do not tolerate low atmospheric pressure, strong ultraviolet and radioactive radiation, which are inherent in the mountains, not to mention the low air temperature. Therefore, a large number of exercises were invented to create a regime of light oxygen starvation in the body. Performing these exercises, a person living in the plains is in the same condition as if he lived in the mountains. The state of light oxygen starvation was achieved with the help of breath holdings of various durations, slowing down breathing, some exercise etc. At the same time, there was always an improvement in the state of health and a cure for certain diseases.

Numerous experiments have already been carried out in our time, when, first, animals, and later people, were temporarily placed in special chambers with a low oxygen content (O 2), both at normal and at reduced atmospheric pressure. At the same time, if the decrease in oxygen content was not excessive, then favorable shifts in the metabolism and functional state of the subjects were always noted. A decrease in the oxygen content in the inhaled air below 10% should be considered excessive. In nature, this corresponds to an altitude of more than 5800 m above sea level. On the plain, the oxygen content in the air is 21%.

It is a remarkable fact that exercises that cause hypoxia in the plains are more beneficial to health than just being in the mountains, even for someone who easily tolerates a mountain climate. This is due to the fact that breathing rarefied mountain air, a person breathes deeper than usual in order to get more oxygen. Deeper inhalations automatically lead to deeper exhalations, and since we are constantly losing with exhalation carbon dioxide(CO 2 ), the deepening of breathing leads to too much of its loss, which can adversely affect health. We note in passing that mountain sickness is associated not only with O 2 deficiency, but also with excessive loss of CO 2 during deep breathing. The air we exhale contains 3.7% CO2, while atmospheric air contains only 0.03%. Holding the breath on the plain, we achieve not only hypoxia - a decrease in the content of O 2 in the tissues, but also hypercapnia - an increase in the content of CO 2 in the tissues.

Carbon dioxide, in turn, has (again, in reasonable quantities) a powerful therapeutic effect on the body. From this it is clear that by doing Hypoxic Breathing Training on the plain, we put the body in more favorable conditions than if we were in the mountains.

There are many interesting and surprising things in human nature. The benefits of such aerobic cyclic exercises as running, swimming, rowing, cycling, skiing, etc. are largely determined by the fact that a mode of moderate (precisely moderate!) Hypoxia is created in the body, when the body's need for oxygen exceeds the ability of the respiratory apparatus to satisfy this need , and hypercapnia, when more carbon dioxide is produced in the body than the body can excrete with the lungs. When East Germany reunited with the West, underground stadiums were discovered on the territory of the former GDR, in which a rarefied climate was artificially created, approaching in its characteristics to the mountain. Training at such stadiums largely determined the success of figure skaters, skaters, rowers and athletes of the former GDR.

Notes:

Aerobic exercise- an exercise in which energy supply is achieved with the help of oxygen (aerobic) oxidation. Performing such an exercise requires a large supply of oxygen.

As you climb mountains, the oxygen pressure in the air steadily decreases, which leads to a drop in this pressure in the alveoli and, as a result, to a drop in oxygen tension in the blood. If the oxygen tension falls below 50-60 mmHg, the oxygen saturation of hemoglobin begins to decrease very rapidly.

Characteristics of physiological changes in breathing in the mountains

Most people do not experience distress when breathing in the mountains up to a height of 2.5 km. This does not mean that at an altitude of 2 km the organism is in the same state as at barometric pressure at sea level. Although at a height of up to 3 km, the blood is saturated with oxygen by no less than 90% of its capacity, the tension of oxygen dissolved in the blood is already reduced here, and this explains a number of observed shifts in breathing in the mountains. These include:

• deepening and slight increase in breathing;
• increased heart rate and increase in minute volume;
• some increase in BCC;
• increased neoplasm of red blood cells;
• a small drop in the excitability of receptors that can be detected only by very subtle methods, disappearing after two or three days of staying at the indicated height.

All these changes during breathing in the mountains in a healthy person, however, are precisely regulatory processes, the normal course of which ensures working capacity at altitude. No wonder staying at an altitude of 1-2 km is sometimes used as a therapeutic technique in the fight against certain diseases.

From a height of 3 km, and in a number of people (in the absence of muscular work) only from a height of 3.5 km, various disorders begin to be detected, which mainly depends on changes in the activity of higher centers. When breathing in the mountains, the tension of oxygen dissolved in the blood decreases, and the amount of oxygen bound by hemoglobin also decreases. Symptoms of respiratory hypoxia occur when blood oxygen saturation falls below 85% of the oxygen capacity of the blood. If oxygen saturation during respiratory hypoxia falls below 50-45% of oxygen capacity, then death occurs in a person.

When the rise to a considerable height is made slowly (for example, when climbing), then symptoms of hypoxia develop, which are not detected with rapidly developing hypoxia, leading to loss of consciousness. In this case, due to a disorder of higher nervous activity, fatigue, drowsiness, trembling, headache, shortness of breath, palpitations, often nausea, and sometimes bleeding (altitude sickness or mountain sickness) are noted.

A change in nervous activity can begin even before the decrease in the amount of oxyhemoglobin in the blood, depending on the decrease in the tension of oxygen dissolved in the blood. In dogs, some changes in nervous activity are sometimes noted already at 1000 m, expressed first in an increase in conditioned reflexes and weakening of inhibitory processes in the cerebral cortex. At a higher altitude, conditioned reflexes decrease, and then (at an altitude of 6-8 km) disappear. Unconditioned reflexes also decrease. In the cerebral cortex, inhibition is enhanced. If not high altitude(2-4 km), changes in conditioned reflexes are noted only at first, then at significant altitudes, disturbances in conditioned reflex activity do not decrease with continued hypoxia, but rather deepen.

Caused by hypoxia from breathing in the mountains, changes in the state of the cerebral cortex, of course, affect the course of all physiological functions. Inhibition developing in the cortex can also be transferred to subcortical formations, which affects both the violation of motor acts and the strengthening of reflexes to impulses from interoreceptors.

Height limit

Depending on individual characteristics, fitness level, when breathing disorders occur in the mountains, may be different, but these disorders, although different heights, are sure to happen to everyone.

For healthy people, on average, the following scale of heights can be indicated, where certain functional changes in the body occur:

• up to an altitude of 2.5 km, most people (and some individuals up to an altitude of 3.5-4 km) do not experience significant disorders. The saturation of blood with oxygen here is even higher than 85% of the oxygen capacity, and of the shifts in the state of the body, only increased activity of the respiratory, cardiovascular systems, as well as increased neoplasm of red blood cells, is characteristic;
• at an altitude of 4-5 km, disorders of higher nervous activity, regulation of respiration, and blood circulation begin to be noted (euphoria or feeling unwell, easy fatigue, Cheyne-Stokes breathing, a sharp increase in heart rate, sometimes collapse);
• at an altitude of 6-7 km, these symptoms become very serious for most people, with the exception of specially trained persons;
• breathing in the mountains at an altitude of 7-8 km always leads to a serious condition and is dangerous for most people, and a height of 8.5 km is the limit above which a person cannot rise without inhaling oxygen.

In animals permanently living in the mountains, there is a significant undersaturation of blood with oxygen. For example, in sheep at an altitude of 4000 m, the oxygen saturation of the blood is only about 65% of the oxygen capacity, but there are no pathological symptoms of hypoxemia.

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4. Movement in the mountains

4.1. What breathing rhythm is recommended when moving on mountain slopes (uphill and downhill)?

GRU special forces training. Movement in the mountains.

steady, not fast

The pace of movement is controlled and regulated by the pulse. The pulse should not be

too frequent (acceleration no more than 1.5-2 times) compared to the usual

pulse at a given height in a given person. And most importantly, the pulse should quickly

calm down, returning to normal 10-15 minutes after stopping. Should

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avoid jerks and sudden movements that disrupt the steady work of the heart. At

lifting, special attention should be paid to the uniformity of breathing and

its consistency with movements. Talking, singing, screaming take your breath away and

therefore unacceptable. In addition to the work of the heart, breathing is the control of the pace: it

should not be excessively fast.

Uniform breathing is a fundamental factor in long-term exercise.

On heavy lifts, the rhythm of breathing is consistent with the frequency of steps. For example, step

left - inhale, step right - exhale. One cycle can take more

steps, i.e. Each step takes a breath in and out.

Regularity in walking and breathing in the mountains saves strength. Breathing should be done

not with the mouth, but with the nose. This especially relieves the tension of the body during prolonged

During movement, you need to follow the rhythm of breathing, breathe calmly, deeply

inhale only through the nose and exhale completely. When going uphill, do not

talk and never smoke. In violation of the normal

breathing rhythm, make short stops for 3-5 minutes.

Regular rhythm, deep infrequent breathing.

The correct breathing rhythm greatly simplifies the ascent. But the catch is

that each person has his own. Moreover, even for the same person

this rhythm depends on the difficulty of the ascent or descent. Usually recommend

with a not very heavy ascent / descent - inhale one step, exhale the other.

With steeper climbs, one step may have to inhale and exhale.

The basic rule is that breathing should be synchronized with steps.

pace, depending on own feelings. I want to breathe more often - breathe

more often, but still evenly.

Inhalation is done through the nose, exhalation through the mouth.

4.2. The group is on a steep uphill. Part of the group wants to go

fast and some slow. What should members of the slow group do?

The "fast group" must adapt to the slow one.

In theory, you just need to go - anyway, everyone will meet at a halt.

1. With this approach, the group runs the risk of stretching too much, and in

As a result, if the laggards need help, there will be no one to help them.

2. If there are turns and forks on the way, then the stragglers not only risk

hopelessly behind, but also get lost.

3. With this approach, those who go quickly rest a lot, and those who are from the last

strength is barely weaving and needs rest more than anyone else - practically

The order of movement when climbing uphill is strictly in a column one at a time. When driving

on steep rockfall slopes, scree, moraine, it is not allowed to find one

tourists right up the slope above the others. If a different order of movement

impossible, then you should move close to each other.

Therefore, they should not be divided into “slow” and “fast” groups - it increases

danger of accidents.

to go as best as they can, but following the integrity of the group, arrange halts more often

Coordinate your pace, it should not exceed the speed with which it can

the most unprepared member of the group moves.

Yura Popov: This is not always possible, because if you go slower than your

internal pace, you will get even more tired. Additionally, there are

people who are convinced that it is easier for them to climb if they rush right now,

and then it is better to stand and rest.

the speed of the caravan is determined by the speed of the slowest camel.

split up and send a fast group ahead, but it still has to where

then wait for the slow part, so it is advisable not to lose from the fast part of the group

mind the slow part of the group.

To agree and go together - organizationally it is much easier. expedient

also redistribute the load (equipment weight) in order to equalize the speed

fast and slow. If it is not possible to agree, and the rise is not too

steep and dangerous, it will be advisable to let the fast ones go ahead.

Yura Popov: No one wants to carry a heavier backpack.

Weight gain measures are only applied to hard-core

at the beginning of the ascent, those who walk slowly become "at the head of the column"

)) as they advance, they find themselves at the end, and those who go quickly,

still have to wait.)

At all complex with a point

in terms of physical activity, climbs, everyone rises exactly at the same pace,

how comfortable it is for him to get up. If you are behind, no need, straining,

run in a hurry for the rest. Walk at your own pace. They will wait for you.

Without a doubt, we came to the mountains in order to gain some experience and

to learn something. But this is the second line. First of all, we came to

mountains because we like to be in the mountains and walk.

Those who have run ahead are careful not to run too far.

Those who are left behind do not allow themselves to relax too much.

There are two main lifting techniques used

participants of previous campaigns in which I participated. The first is fast

small climbs with frequent stops. The second is slow ascents without

stops or with very rare and short stops. Basically, the speed

it turns out approximately the same, since while the slow ones are moving, the fast ones are resting.

The second method is more physiological, since sharp jumps in load

(rested - ran sharply; ran-ran - stopped abruptly) give a very strong

stress on the heart and can quickly exhaust. Not for nothing even when running on a flat

fast walking, then slower walking, and only then stop.

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breathe in one step inhale + exhale stop abruptly and immediately breathe very

rarely. Breathe often for a while, slow down the rate of breathing gradually.

at a slow pace without unnecessary stops, and only then choose for yourself,

which method do you like best. Feeling the best fit for you

pace will come to you with experience.

4.3. How to climb and / or descend from steep slopes (when you can still

walk without climbing)?

To successfully move on steep slopes, it is important to have shoes on corrugated,

non-slip soles, as well as master some walking techniques.

At the same time, one should try to keep the horizontal position of the foot,

using each firmly lying stone, a slight bulge of the slope,

which are stepped on with the heel of the boot.

The steeper the slope, the more you need to spread your toes. During a long climb

slowly, gloved hands, at long intervals

Yura Popov: About gloved hands - this is from personal experience. Last year Zheka

I cut my hand very badly, falling almost out of the blue.

along the "serpentine" zigzag

it is difficult to describe this process. please show. in one word - sideways.

Zigzag. The steeper the slope, the longer the zigzag.

The leg must be placed on the entire foot. The steeper the slope, the shorter the stride.

With a steep descent (including, in the presence of steep "steps") -

we go down sideways, with legs bent at the knees.

Don't run - you can't stop.

As for the gloves, very useful advice. I want to buy myself this year.

4.4. List a few rules to follow while driving

on a very steep descent (climbing)?

The basic rule to be followed when driving on a very steep

slope (rock) - this is the rule of "three points of support": you need to move so that on

more or less difficult sections while moving one limb to the other

did not break away from the supports.

On light rocks, the arms usually only maintain balance and actively work.

only where there is no comfortable and reliable support for the legs. The torso is necessary

the ability to hold upright, and spread arms and legs for at least

shoulder width. The protrusions should be supported by the inner welts of the boots.

It is necessary to move smoothly, without jerks - it is easier to maintain balance and

put on gloves 🙂 climb carefully, keep your balance, carefully

look after the safety of the road

To save energy when crossing the mountains, you need to choose the route most

easy, even if it is not the shortest, set the rate (in hours) of the daily

transition and withstand it, bypass the obstacles encountered on the way, in all

cases, try to go down to the valley and walk along it.

When driving on mountainous rough terrain, maintain the direction

outlining in the distance characteristic landmarks. When crossing an obstacle,

driving on steep slopes, glacier, when descending from mountains, observe

be careful, use insurance. When descending, a strong

stick with a point on the end.

When descending a steep slope, before stepping with your foot, check the strength

supports. Sometimes a rock break can cause a rockfall in the mountains, a collapse that

can draw a person in.

When the weather worsens in the mountains (heavy rain, snowstorm, fog, storm, etc.)

should not move. In the mountains, it is important to observe safety measures, to be

careful and rational use of their forces.

you brought helpful tips, which you need to know when driving in the mountains in general,

not only when driving on a steep slope. Therefore, I am adding them.

in common list answers. However, the question concerns movement precisely along

steep slope. Insurance in our case is not applicable, since it is simply

no. And there will be no slopes that cannot be passed without insurance;

even if we meet such, we will no doubt bypass them.

Are there any other tips besides checking the strength of the support?

When walking in the mountains, you should pay special attention to the technique itself.

step. The foot should be placed on the entire foot, carefully choosing a place, feet

placed parallel to one another, the climber looks under his feet. Leg is put

on the entire foot both on the plain and when lifting. Transferring weight from one

feet on the other should be smooth, this saves strength and reduces the possibility

slip. The step should not be too wide, soft, the gait should be slightly

springy, excessively strong rocking causes an unnecessary loss of strength. Pace

movement depends entirely on the strength of the group, and precise instructions are to be given here

The protrusions should be supported by the inner welts of the boots. Never

cross your legs. When using the grip, do not press against the rocks. it

provide Better conditions for footwork. You need to move smoothly, without jerks -

alternately use stops and spacers, preferring the latter: with spacers

less risk of slip and stress on the fingers. On difficult but comfortable for

movement with spacer sections should move straight up. If it is needed

move to the side, you need to do this in easier areas. When

the absence or insufficiency of reliable supports on a rocky area should

perhaps make fuller use of friction (on plates, scallops) and force

wedging (corner, crevices).

Movements should be smooth, uniform, unhurried

Suspect every ledge or stone of "unreliability."

Do not approach the person climbing in front, and look at his path in order to plan your own.

According to the degree of impact of climatic and geographical factors on a person, the existing classification subdivides (conditionally) mountain levels into:

Lowlands - up to 1000 m. Here a person does not experience (compared to the area located at sea level) the negative effect of a lack of oxygen even during hard work;

Middle Mountains - ranging from 1000 to 3000 m. Here, under conditions of rest and moderate activity, no significant changes occur in the body of a healthy person, since the body easily compensates for the lack of oxygen;

Highlands - over 3000 m. These heights are characterized by the fact that even at rest in the body of a healthy person, a complex of changes caused by oxygen deficiency is detected.

If at medium altitudes the human body is affected by the whole complex of climatic and geographical factors, then at high mountains, the lack of oxygen in the tissues of the body, the so-called hypoxia, is of decisive importance.

Highlands, in turn, can also be conditionally divided (Fig. 1) into the following zones (according to E. Gippenreiter):

a) Full acclimatization zone - up to 5200-5300 m. In this zone, due to the mobilization of all adaptive reactions, the body successfully copes with oxygen deficiency and the manifestation of other negative factors of altitude. Therefore, here it is still possible to have long-term posts, stations, etc., that is, to live and work permanently.

b) Zone of incomplete acclimatization - up to 6000 m. Here, despite the commissioning of all compensatory-adaptive reactions, the human body can no longer fully counteract the influence of height. With a long (for several months) stay in this zone, fatigue develops, a person weakens, loses weight, atrophy of muscle tissues is observed, activity decreases sharply, the so-called high-altitude deterioration develops - a progressive deterioration in the general condition of a person with prolonged stay at high altitudes.

c) Adaptation zone - up to 7000 m. The adaptation of the body to altitude here is of a short, temporary nature. Even with a relatively short stay (on the order of two or three weeks) at such altitudes, adaptation reactions become depleted. In this regard, the body shows clear signs of hypoxia.

d) Zone of partial adaptation - up to 8000 m. When staying in this zone for 6-7 days, the body cannot provide the necessary amount of oxygen even to the most important organs and systems. Therefore, their activities are partially disrupted. Thus, the reduced efficiency of systems and organs responsible for replenishing energy costs does not ensure the restoration of strength, and human activity is largely due to reserves. At such altitudes, severe dehydration of the body occurs, which also worsens its general condition.

e) Limit (lethal) zone - over 8000 m. Gradually losing resistance to the action of heights, a person can stay at these heights due to internal reserves only for an extremely limited time, about 2 - 3 days.

The above values ​​of the altitudinal boundaries of the zones are, of course, average values. Individual tolerance, as well as a number of factors outlined below, can change the indicated values ​​\u200b\u200bfor each climber by 500 - 1000 m.

The body's adaptation to altitude depends on age, sex, physical and mental state, degree of fitness, degree and duration of oxygen starvation, intensity of muscle effort, and the presence of high-altitude experience. An important role is played by the individual resistance of the organism to oxygen starvation. Previous diseases, malnutrition, insufficient rest, lack of acclimatization significantly reduce the body's resistance to mountain sickness - special condition organism that occurs when inhaling rarefied air. Of great importance is the speed of climb. These conditions explain the fact that some people feel some signs of mountain sickness already at relatively low altitudes - 2100 - 2400 m, others are resistant to them up to 4200 - 4500 m, but when climbing to a height of 5800 - 6000 m signs of altitude sickness, expressed in varying degrees, appear in almost all people.

The development of mountain sickness is also influenced by some climatic and geographical factors: increased solar radiation, low air humidity, prolonged low temperatures and their sharp difference between night and day, strong winds, the degree of electrification of the atmosphere. Since these factors depend, in turn, on the latitude of the area, remoteness from water spaces, and similar reasons, the same height in different mountainous regions of the country has a different effect on the same person. For example, in the Caucasus, signs of mountain sickness can appear already at altitudes of 3000-3500 m, in Altai, Fann mountains and Pamir-Alai - 3700 - 4000 m, Tien Shan - 3800-4200 m and Pamir - 4500-5000 m.

Signs and effects of altitude sickness

Altitude sickness can come on suddenly, especially when the person short span time, he significantly exceeded the boundaries of his individual tolerance, experienced excessive overstrain in conditions of oxygen starvation. However, most mountain sickness develops gradually. Its first signs are general fatigue, which does not depend on the amount of work performed, apathy, muscle weakness, drowsiness, malaise, dizziness. If a person continues to remain at a height, then the symptoms of the disease increase: digestion is disturbed, frequent nausea and even vomiting are possible, respiratory rhythm disorder, chills and fever appear. The recovery process is rather slow.

In the early stages of the development of the disease, no special treatment measures are required. Most often, after active work and proper rest, the symptoms of the disease disappear - this indicates the onset of acclimatization. Sometimes the disease continues to progress, passing into the second stage - chronic. Its symptoms are the same, but expressed to a much stronger degree: the headache can be extremely acute, drowsiness is more pronounced, the vessels of the hands are full of blood, nosebleeds are possible, shortness of breath is pronounced, the chest becomes wide, barrel-shaped, increased irritability is observed, it is possible loss of consciousness. These signs indicate a serious illness and the need for urgent transportation of the patient down. Sometimes the listed manifestations of the disease are preceded by a stage of excitation (euphoria), which is very reminiscent of alcohol intoxication.

The mechanism of the development of mountain sickness is associated with insufficient blood oxygen saturation, which affects the functions of many internal organs and systems. Of all the tissues in the body, the nervous system is the most sensitive to oxygen deficiency. In a person who got to a height of 4000 - 4500 m and prone to mountain sickness, as a result of hypoxia, arousal first arises, expressed in the appearance of a feeling of complacency and own strength. He becomes cheerful, talkative, but at the same time loses control over his actions, cannot really assess the situation. After a while, a period of depression sets in. Gaiety is replaced by sullenness, grumpiness, even pugnacity, and even more dangerous bouts of irritability. Many of these people do not rest in a dream: the dream is restless, accompanied by fantastic dreams that are in the nature of bad forebodings.

At higher altitudes, hypoxia has a more severe effect on functional state higher nerve centers, causing dulling of sensitivity, impaired judgment, loss of self-criticism, interest and initiative, and sometimes loss of memory. The speed and accuracy of the reaction noticeably decreases, as a result of the weakening of the processes of internal inhibition, the coordination of movement is upset. Mental and physical depression appears, expressed in slowness of thinking and actions, a noticeable loss of intuition and the ability to think logically, and a change in conditioned reflexes. However, at the same time, a person believes that his consciousness is not only clear, but also unusually sharp. He continues to do what he was doing before the severe effects of hypoxia on him, despite the sometimes dangerous consequences of his actions.

The sick person may develop an obsession, a sense of the absolute correctness of his actions, intolerance of critical remarks, and this, if the head of the group, a person responsible for the lives of other people, is in such a state, becomes especially dangerous. It has been observed that under the influence of hypoxia, people often do not make any attempts to get out of a clearly dangerous situation.

It is important to know what are the most common changes in human behavior that occur at altitude under the influence of hypoxia. In terms of frequency of occurrence, these changes are arranged in the following sequence:

Disproportionately large efforts in the performance of the task;

More critical attitude towards other participants of the trip;

Unwillingness to do mental work;

Increased irritability of the senses;

Touchiness;

Irritability with comments on work;

Difficulty concentrating;

Slow thinking;

Frequent, obsessive return to the same topic;

Difficulty in remembering.

As a result of hypoxia, thermoregulation can also be disturbed, due to which, in some cases, at low temperatures, the production of heat by the body decreases, and at the same time, its loss through the skin increases. Under these conditions, a person with mountain sickness is more susceptible to cooling than other participants in the trip. In other cases, chills and an increase in body temperature by 1-1.5 ° C are possible.

Hypoxia also affects many other organs and systems of the body.

Respiratory system.

If at rest a person at a height does not experience shortness of breath, lack of air or difficulty breathing, then when physical activity in high-altitude conditions, all these phenomena begin to be noticeably felt. For example, one of the participants in climbing Everest took 7-10 full breaths and exhalations for each step at an altitude of 8200 meters. But even with such a slow pace of movement, he rested for up to two minutes every 20-25 meters of the path. Another participant of the ascent in one hour of movement, while being at an altitude of 8500 meters, climbed along a fairly easy section to a height of only about 30 meters.

Working capacity.

It is well known that any muscle activity, and especially intense, is accompanied by an increase in blood supply to the working muscles. However, if in plain conditions the body can provide the required amount of oxygen relatively easily, then with the ascent to a great height, even with the maximum use of all adaptive reactions, the supply of oxygen to the muscles is disproportionate to the degree of muscle activity. As a result of this mismatch, oxygen starvation, and under-oxidized metabolic products accumulate in the body in excess quantities. Therefore, human performance decreases sharply with increasing height. So (according to E. Gippenreiter) at an altitude of 3000 m it is 90%, at an altitude of 4000 m. -80%, 5500 m- 50%, 6200 m- 33% and 8000 m- 15-16% of the maximum level of work done at sea level.

Even at the end of work, despite the cessation of muscle activity, the body continues to be in tension, consuming some time increased amount oxygen in order to eliminate the oxygen debt. It should be noted that the time during which this debt is liquidated depends not only on the intensity and duration of muscle work, but also on the degree of training of a person.

The second, although less important reason for the decrease in the body's performance is the overload of the respiratory system. It is the respiratory system, by strengthening its activity to certain time can compensate for the sharply increasing oxygen demand of the body in a rarefied air environment.

Table 1

However, the possibilities of pulmonary ventilation have their own limit, which the body reaches before the maximum working capacity of the heart occurs, which reduces the required amount of oxygen consumed to a minimum. Such restrictions are explained by the fact that a decrease in the partial pressure of oxygen leads to an increase in pulmonary ventilation, and, consequently, to an increased "washout" of CO 2 from the body. But a decrease in the partial pressure of CO 2 reduces the activity of the respiratory center and thereby limits the volume of pulmonary ventilation.

At altitude, pulmonary ventilation reaches the limit values ​​already when the load is average for normal conditions. That's why maximum amount intensive work for a certain time that a tourist can complete in high mountains, less, and recovery period after work in the mountains is longer than at sea level. However, with a long stay at the same altitude (up to 5000-5300 m) due to the acclimatization of the body, the level of working capacity increases.

The digestive system.

At altitude, appetite changes significantly, the absorption of water and nutrients decreases, the secretion of gastric juice decreases, the functions of the digestive glands change, which leads to disruption of the processes of digestion and absorption of food, especially fats. As a result, a person loses weight dramatically. So, during one of the expeditions to Everest, climbers who lived at an altitude of more than 6000 m within 6-7 weeks, lost in weight from 13.6 to 22.7 kg. At a height, a person can feel an imaginary feeling of fullness in the stomach, fullness in epigastric region, nausea, diarrhea, not amenable to drug treatment.

Vision.

At altitudes of about 4500 m normal visual acuity is possible only at a brightness 2.5 times greater than normal for flat conditions. At these heights, there is a narrowing of the peripheral field of vision and a noticeable "fogging" of vision in general. At high altitudes, the accuracy of fixing the gaze and the correctness of determining the distance also decrease. Even in mid-mountain conditions, vision weakens at night, and the period of adaptation to darkness lengthens.

pain sensitivity

as hypoxia increases, it decreases up to its complete loss.

Dehydration of the body.

The excretion of water from the body, as is known, is carried out mainly by the kidneys (1.5 liters of water per day), skin (1 liter), lungs (about 0.4 l) and intestines (0.2-0.3 l). It has been established that the total water consumption in the body, even in a state of complete rest, is 50-60 G in hour. With average physical activity in normal climatic conditions at sea level, water consumption increases to 40-50 grams per day for every kilogram of human weight. In total, on average, under normal conditions, about 3 l water. With increased muscular activity, especially in hot conditions, the release of water through the skin sharply increases (sometimes up to 4-5 liters). But intense muscular work performed in high altitude conditions, due to lack of oxygen and dry air, sharply increases pulmonary ventilation and thereby increases the amount of water released through the lungs. All this leads to the fact that the total loss of water for participants in difficult high-mountain trips can reach 7-10 l per day.

Statistics show that in high altitude conditions more than doubles morbidity of the respiratory system. Inflammation of the lungs often takes on a croupous form, proceeds much more severely, and the resorption of inflammatory foci is much slower than in plain conditions.

Inflammation of the lungs begins after physical overwork and hypothermia. In the initial stage, it is noted bad feeling, some shortness of breath, rapid pulse, cough. But after about 10 hours, the patient's condition deteriorates sharply: the respiratory rate is over 50, the pulse is 120 per minute. Despite taking sulfonamides, after 18-20 hours, pulmonary edema develops, which in high altitude conditions great danger. The first signs of acute pulmonary edema: dry cough, complaints of pressure slightly below the sternum, shortness of breath, weakness during exercise. In serious cases, there is hemoptysis, suffocation, severe confusion, followed by death. The course of the disease often does not exceed one day.

The basis for the formation of pulmonary edema at altitude is, as a rule, the phenomenon of increased permeability of the walls of the pulmonary capillaries and alveoli, as a result of which foreign substances (protein masses, blood elements and microbes) penetrate into the alveoli of the lungs. Therefore, the useful capacity of the lungs is sharply reduced in a short time. Hemoglobin of arterial blood, washing the outer surface of the alveoli, filled not with air, but with protein masses and blood elements, cannot be adequately saturated with oxygen. As a result of insufficient (below allowable rate) supplying oxygen to body tissues, a person quickly dies.

Therefore, even in case of the slightest suspicion of a respiratory disease, the group must immediately take measures to bring the sick person down as soon as possible, preferably to an altitude of about 2000-2500 meters.

The mechanism of development of mountain sickness

Dry atmospheric air contains: 78.08% nitrogen, 20.94% oxygen, 0.03% carbon dioxide, 0.94% argon and 0.01% other gases. When rising to a height, this percentage does not change, but the density of the air changes, and, consequently, the magnitude of the partial pressures of these gases.

According to the law of diffusion, gases pass from an environment with a higher partial pressure to an environment with a lower pressure. Gas exchange, both in the lungs and in human blood, is carried out due to the existing difference in these pressures.

At normal atmospheric pressure 760 mmp t. st. partial pressure of oxygen is:

760x0.2094=159 mmHg Art., where 0.2094 is the percentage of oxygen in the atmosphere, equal to 20.94%.

Under these conditions, the partial pressure of oxygen in the alveolar air (inhaled with air and entering the alveoli of the lungs) is about 100 mmHg Art. Oxygen is poorly soluble in blood, but it binds to the hemoglobin protein found in red blood cells - erythrocytes. Under normal conditions, due to the high partial pressure of oxygen in the lungs, hemoglobin in arterial blood is saturated with oxygen up to 95%.

When passing through the capillaries of tissues, hemoglobin in the blood loses about 25% of oxygen. Therefore, venous blood carries up to 70% oxygen, the partial pressure of which, as can be easily seen from the graph (Fig. 2), is

0 10 20 30 40 50 60 70 80 90 100

Partial pressure of oxygen mm .pm .cm.

Rice. 2.

at the time of flow venous blood to the lungs at the end of the circulation cycle only 40 mmHg Art. Thus, there is a significant pressure difference between venous and arterial blood, equal to 100-40=60 mmHg Art.

Between carbon dioxide inhaled with air (partial pressure 40 mmHg Art.), and carbon dioxide flowing with venous blood to the lungs at the end of the circulatory cycle (partial pressure 47-50 mmHg.), differential pressure is 7-10 mmHg Art.

As a result of the existing pressure drop, oxygen passes from the pulmonary alveoli into the blood, and directly in the tissues of the body, this oxygen diffuses from the blood into the cells (into an environment with an even lower partial pressure). Carbon dioxide, on the contrary, first passes from the tissues into the blood, and then, when venous blood approaches the lungs, from the blood into the alveoli of the lung, from where it is exhaled into the surrounding air. (Fig. 3).

Rice. 3.

With ascent to altitude, the partial pressures of gases decrease. So, at an altitude of 5550 m(corresponding to an atmospheric pressure of 380 mmHg Art.) for oxygen it is:

380x0.2094=80 mmHg Art.,

that is, it is reduced by half. At the same time, of course, the partial pressure of oxygen in the arterial blood also decreases, as a result of which not only the saturation of blood hemoglobin with oxygen decreases, but also due to a sharp reduction in the pressure difference between arterial and venous blood, the transfer of oxygen from blood to tissues worsens significantly. This is how oxygen deficiency-hypoxia occurs, which can lead to a person's illness with mountain sickness.

Naturally, a number of protective compensatory-adaptive reactions arise in the human body. So, first of all, the lack of oxygen leads to the excitation of chemoreceptors - nerve cells, which are very sensitive to a decrease in the partial pressure of oxygen. Their excitation serves as a signal for deepening and then quickening of breathing. The resulting expansion of the lungs increases their alveolar surface and thereby contributes to a more rapid saturation of hemoglobin with oxygen. Thanks to this, as well as a number of other reactions, a large amount of oxygen enters the body.

However, with increased respiration, ventilation of the lungs increases, during which there is an increased excretion (“washing out”) of carbon dioxide from the body. This phenomenon is especially enhanced with the intensification of work in high altitude conditions. So, if on the plain at rest within one minute approximately 0.2 l CO 2, and during hard work - 1.5-1.7 l, then in high altitude conditions, on average, the body loses about 0.3-0.35 per minute l CO 2 at rest and up to 2.5 l during intense muscular work. As a result, there is a lack of CO 2 in the body - the so-called hypocapnia, characterized by a decrease in the partial pressure of carbon dioxide in arterial blood. But carbon dioxide plays an important role in regulating the processes of respiration, circulation and oxidation. A serious lack of CO 2 can lead to paralysis of the respiratory center, to sharp drop blood pressure, deterioration of the work of the heart, to a violation of nervous activity. Thus, a decrease in CO 2 blood pressure by 45 to 26 mm. r t. reduces blood circulation to the brain by almost half. That is why cylinders designed for breathing at high altitudes are not filled with pure oxygen, and its mixture with 3-4% carbon dioxide.

A decrease in the content of CO 2 in the body disrupts the acid-base balance towards an excess of alkalis. Trying to restore this balance, the kidneys intensively remove this excess of alkalis from the body along with urine for several days. Thus, acid-base balance is achieved at a new, lower level, which is one of the main signs of the completion of the adaptation period (partial acclimatization). But at the same time, the value of the alkaline reserve of the body is violated (decreases). In case of mountain sickness, a decrease in this reserve contributes to its further development. This is explained by the fact that a rather sharp decrease in the amount of alkalis reduces the ability of the blood to bind acids (including lactic acid) that are formed during hard work. This in a short time changes the acid-base ratio in the direction of an excess of acids, which disrupts the work of a number of enzymes, leads to disorganization of the metabolic process and, most importantly, inhibition of the respiratory center occurs in a seriously ill patient. As a result, breathing becomes shallow, carbon dioxide is not completely removed from the lungs, accumulates in them and prevents oxygen from reaching hemoglobin. At the same time, suffocation quickly sets in.

From all that has been said, it follows that although the main cause of mountain sickness is a lack of oxygen in the tissues of the body (hypoxia), the lack of carbon dioxide (hypocapnia) also plays a rather large role here.

Acclimatization

With a long stay at a height in the body, a number of changes occur, the essence of which is to preserve the normal functioning of a person. This process is called acclimatization. Acclimatization - the sum of adaptive-compensatory reactions of the body, as a result of which a good general condition is maintained, weight is maintained constant, normal performance and the normal course of psychological processes. Distinguish between complete and incomplete, or partial, acclimatization.

Due to the relatively short period of stay in the mountains, mountain tourists and climbers are characterized by partial acclimatization and adaptation-short-term(as opposed to the final or long-term) adaptation of the body to new climatic conditions.

In the process of adaptation to a lack of oxygen in the body, the following changes occur:

Since the cerebral cortex is extremely high sensitivity to oxygen insufficiency, the body in high altitude conditions primarily seeks to maintain proper oxygen supply to the central nervous system by reducing the supply of oxygen to other, less important organs;

The respiratory system is also largely sensitive to a lack of oxygen. The respiratory organs react to the lack of oxygen first by deeper breathing (increasing its volume):

table 2

and then an increase in the frequency of breathing:

As a result of some reactions caused by oxygen deficiency, not only the number of erythrocytes (red blood cells containing hemoglobin), but also the amount of hemoglobin itself (Fig. 4).

All this causes an increase in the oxygen capacity of the blood, that is, the ability of the blood to carry oxygen to the tissues and thus supply the tissues with the necessary amount of it increases. It should be noted that the increase in the number of erythrocytes and the percentage of hemoglobin is more pronounced if the ascent is accompanied by an intense muscle load, that is, if the adaptation process is active. The degree and rate of growth in the number of erythrocytes and hemoglobin content also depend on the geographical features of certain mountainous regions.

Increases in the mountains and total circulating blood. However, the load on the heart does not increase, since at the same time there is an expansion of capillaries, their number and length increase.

In the first days of a person's stay in high mountains (especially in poorly trained people), the minute volume of the heart increases, and the pulse increases. So, for physically poorly trained climbers at a height 4500m pulse increases by an average of 15, and at an altitude of 5500 m - at 20 beats per minute.

At the end of the acclimatization process at altitudes up to 5500 m all of these parameters are reduced to normal values, typical for normal activities at low altitudes. The normal functioning of the gastrointestinal tract is also restored. However, at high altitudes (more than 6000 m) pulse, respiration, the work of the cardiovascular system never decrease to a normal value, because here some organs and systems of a person are constantly under conditions of a certain tension. So, even during sleep at altitudes of 6500-6800 m the pulse rate is about 100 beats per minute.

It is quite obvious that for each person the period of incomplete (partial) acclimatization has different duration. It occurs much faster and with less functional deviations in physically healthy people aged 24 to 40 years. But in any case, a 14-day stay in the mountains under conditions of active acclimatization is sufficient for a normal organism to adapt to new climatic conditions.

To exclude the possibility of a serious illness with mountain sickness, as well as to reduce the time of acclimatization, the following set of measures can be recommended, carried out both before leaving for the mountains and during the trip.

Before a long alpine journey, including passes above 5000 m in the route of its route m, all candidates must be subjected to a special medical-physiological examination. Persons who do not tolerate oxygen deficiency, are physically insufficiently prepared, and who have suffered pneumonia, tonsillitis or serious influenza during the pre-trek training period, should not be allowed to participate in such trips.

The period of partial acclimatization can be shortened if the participants of the upcoming trip, a few months before going to the mountains, start regular general physical training, especially to increase the endurance of the body: long-distance running, swimming, underwater sports, skating and skiing. During such training, a temporary lack of oxygen occurs in the body, which is the higher, the greater the intensity and duration of the load. Since the body works here in conditions that are somewhat similar in terms of oxygen deficiency to staying at a height, a person develops an increased resistance of the body to a lack of oxygen when performing muscular work. In the future, in mountainous conditions, this will facilitate adaptation to height, speed up the process of adaptation, and make it less painful.

You should know that for tourists who are physically unprepared for a high-mountain trip, the vital capacity of the lungs at the beginning of the trip even slightly decreases, the maximum performance of the heart (compared to trained participants) also becomes 8-10% less, and the reaction of increasing hemoglobin and erythrocytes with oxygen deficiency is delayed .

The following activities are carried out directly during the trip: active acclimatization, psychotherapy, psychoprophylaxis, organization of appropriate nutrition, the use of vitamins and adaptogens (means that increase the body's performance), complete failure from smoking and alcohol, systematic condition control health, the use of certain drugs.

Active acclimatization for mountain climbing and for high-altitude hiking trips, it has a difference in the methods of its implementation. This difference is explained, first of all, by a significant difference in the heights of the climbing objects. So, if for climbers this height can be 8842 m, then for the most prepared tourist groups it will not exceed 6000-6500 m(several passes in the region of the High Wall, Zaalai and some other ridges in the Pamirs). The difference lies in the fact that climbing to the peaks along technically difficult routes takes several days, and on difficult traverses - even weeks (without significant loss of height at certain intermediate stages), while in high-mountain hiking trips that have, as a rule, a greater length, it takes less time to overcome the passes.

Lower heights, shorter stay on these W- honeycombs and a faster descent with a significant loss of altitude to a greater extent facilitate the process of acclimatization for tourists, and quite multiple the alternation of ascents and descents softens, and even stops the development of mountain sickness.

Therefore, climbers during high-altitude ascents are forced at the beginning of the expedition to allocate up to two weeks for training (acclimatization) ascents to lower peaks, which differ from the main object of ascent to a height of about 1000 meters. For tourist groups, whose routes pass through passes with a height of 3000-5000 m, special acclimatization exits are not required. For this purpose, as a rule, it is enough to choose such a route route, in which during the first week - 10 days the height of the passes passed by the group would increase gradually.

Since the greatest discomfort caused by general fatigue a tourist who has not yet become involved in the hiking life is usually felt in the first days of the hike, then even when organizing a day trip at this time, it is recommended to conduct classes in movement technique, in the construction of snow huts or caves, as well as exploration or training exits to a height. These practical exercises and exits should be carried out at a good pace, which makes the body react faster to rarefied air, more actively adapt to changes in climatic conditions. N. Tenzing's recommendations are interesting in this regard: at a height, even at a bivouac, you need to be physically active - warm snow water, monitor the condition of the tents, check equipment, move more, for example, after setting up the tents, take part in the construction of a snow kitchen, help distribute prepared food by tents.

Important in the prevention of mountain sickness is proper organization nutrition. At an altitude of over 5000 m the daily diet should have at least 5000 large calories. The content of carbohydrates in the diet should be increased by 5-10% compared to the usual diet. In areas associated with intense muscle activity, first of all, an easily digestible carbohydrate - glucose should be consumed. Increased carbohydrate intake contributes to the formation of more carbon dioxide, which the body lacks. The amount of fluid consumed in high altitude conditions and, especially, when performing intensive work associated with movement along difficult sections of the route, should be at least 4-5 l per day. This is the most decisive measure in the fight against dehydration. In addition, an increase in the volume of fluid consumed contributes to the removal of underoxidized metabolic products from the body through the kidneys.

The body of a person who prolonged intensive work in high mountains requires an increased (2-3 times) amount of vitamins, especially those that are part of the enzymes involved in the regulation of redox processes and are closely related to metabolism. These are B vitamins, where B 12 and B 15 are the most important, as well as B 1, B 2 and B 6. So, vitamin B 15, in addition to the above, helps to increase the body's performance at altitude, greatly facilitating the performance of large and intense loads, increases the efficiency of oxygen use, activates oxygen metabolism in tissue cells, and increases altitude stability. This vitamin enhances the mechanism of active adaptation to a lack of oxygen, as well as fat oxidation at altitude.

In addition to them, vitamins C, PP and folic acid in combination with iron glycerophosphate and metacil also play an important role. Such a complex has an effect on an increase in the number of red blood cells and hemoglobin, that is, an increase in the oxygen capacity of the blood.

The acceleration of adaptation processes is also influenced by the so-called adaptogens - ginseng, eleutherococcus and acclimatizin (a mixture of eleutherococcus, lemongrass and yellow sugar). E. Gippenreiter recommends the following complex of drugs that increase the body's adaptability to hypoxia and facilitate the course of mountain sickness: eleutherococcus, diabazole, vitamins A, B 1, B 2, B 6, B 12, C, PP, calcium pantothenate, methionine, calcium gluconate, calcium glycerophosphate and potassium chloride. The mixture proposed by N. Sirotinin is also effective: 0.05 g of ascorbic acid, 0.5 G. citric acid and 50 g of glucose per dose. We can also recommend a dry blackcurrant drink (in briquettes of 20 G), containing citric and glutamic acids, glucose, sodium chloride and phosphate.

How long, upon returning to the plain, does the organism retain the changes that have occurred in it during the process of acclimatization?

At the end of the journey in the mountains, depending on the altitude of the route, the changes acquired in the process of acclimatization in the respiratory system, blood circulation and the composition of the blood itself pass quickly enough. So, increased content hemoglobin decreases to normal in 2-2.5 months. Over the same period, the increased ability of the blood to carry oxygen also decreases. That is, the acclimatization of the body to the height lasts only up to three months.

True, after repeated trips to the mountains, a kind of “memory” is developed in the body for adaptive reactions to altitude. Therefore, at the next trip to the mountains, its organs and systems, already along the “beaten paths”, quickly find the right way to adapt the body to a lack of oxygen.

Help for mountain sickness

If, despite the measures taken, any of the participants in the high-mountain hike shows symptoms of altitude sickness, it is necessary:

For headaches, take Citramon, Pyramidone (no more than 1.5 g per day), Analgin (no more than 1 G for a single dose and 3 g per day) or their combinations (troychatka, quintuple);

With nausea and vomiting - Aeron, sour fruits or their juices;

For insomnia - noxiron, when a person falls asleep badly, or Nembutal, when sleep is not deep enough.

When using drugs in high altitude conditions, special care should be taken. First of all, this applies to biological active substances(phenamine, phenatin, pervitin), stimulating the activity of nerve cells. It should be remembered that these substances create only a short-term effect. Therefore, it is better to use them only when absolutely necessary, and even then already during the descent, when the duration of the upcoming movement is not long. An overdose of these drugs leads to exhaustion of the nervous system, to a sharp decrease in efficiency. An overdose of these drugs is especially dangerous in conditions of prolonged oxygen deficiency.

If the group decided to urgently descend the sick participant, then during the descent it is necessary not only to systematically monitor the patient's condition, but also regularly inject antibiotics and drugs that stimulate the human heart and respiratory activity (lobelia, cardiamine, corazol or norepinephrine).

SUN EXPOSURE

Sun burns.

From prolonged exposure to the sun on the human body, sunburns form on the skin, which can cause a painful condition for a tourist.

Solar radiation is a stream of rays of the visible and invisible spectrum, which have different biological activity. When exposed to the sun, there is a simultaneous effect of:

Direct solar radiation;

Scattered (arrived due to the scattering of part of the flow of direct solar radiation in the atmosphere or reflection from clouds);

Reflected (as a result of the reflection of rays from surrounding objects).

The magnitude of the flow of solar energy falling on one or another specific area of ​​the earth's surface depends on the height of the sun, which, in turn, is determined by the geographical latitude of this area, the time of year and day.

If the sun is at its zenith, then its rays travel the shortest path through the atmosphere. At a standing height of the sun of 30 °, this path doubles, and at sunset - 35.4 times more than with a sheer fall of the rays. Passing through the atmosphere, especially through its lower layers containing particles of dust, smoke and water vapor in suspension, the sun's rays are absorbed and scattered to a certain extent. Therefore, the greater the path of these rays through the atmosphere, the more polluted it is, the lower the intensity of solar radiation they have.

With the rise to a height, the thickness of the atmosphere through which the sun's rays pass decreases, and the most dense, moistened and dusty lower layers are excluded. Due to the increase in the transparency of the atmosphere, the intensity of direct solar radiation increases. The nature of the change in intensity is shown in the graph (Fig. 5).

Here, the flux intensity at sea level is taken as 100%. The graph shows that the amount of direct solar radiation in the mountains increases significantly: by 1-2% with an increase for every 100 meters.

The total intensity of the direct solar radiation flux, even at the same height of the sun, changes its value depending on the season. Thus, in summer, due to an increase in temperature, increasing humidity and dustiness reduce the transparency of the atmosphere to such an extent that the magnitude of the flux at a sun height of 30 ° is 20% less than in winter.

However, not all components of the spectrum of sunlight change their intensity to the same extent. The intensity increases especially ultraviolet rays are the most active physiologically: it has a pronounced maximum at a high position of the sun (at noon). The intensity of these rays during this period in the same weather conditions is the time required for

redness of the skin, at a height of 2200 m 2.5 times, and at an altitude of 5000 m 6 times less than at an altitude of 500 winds (Fig. 6). With a decrease in the height of the sun, this intensity drops sharply. So, for a height of 1200 m this dependence is expressed by the following table (the intensity of ultraviolet rays at a sun height of 65 ° is taken as 100%):

Table4

If the clouds of the upper tier weaken the intensity of direct solar radiation, usually only to an insignificant extent, then the denser clouds of the middle and especially the lower tiers can reduce to zero. .

Diffused radiation plays a significant role in the total amount of incoming solar radiation. Scattered radiation illuminates places that are in the shade, and when the sun closes over some area with dense clouds, it creates a general daylight illumination.

The nature, intensity and spectral composition of scattered radiation are related to the height of the sun, the transparency of the air and the reflectivity of clouds.

Scattered radiation in a clear sky without clouds, caused mainly by atmospheric gas molecules, in its own way spectral composition differs sharply both from other types of radiation, and from scattered in a cloudy sky. The maximum energy in its spectrum is shifted to shorter wavelengths. And although the intensity of scattered radiation in a cloudless sky is only 8-12% of the intensity of direct solar radiation, the abundance of ultraviolet rays in the spectral composition (up to 40-50% of the total number of scattered rays) indicates its significant physiological activity. The abundance of short-wavelength rays also explains the bright blue color of the sky, the blueness of which is the more intense, the cleaner the air.

In the lower layers of the air, when the sun's rays are scattered from large suspended particles of dust, smoke and water vapor, the intensity maximum shifts to the region of longer waves, as a result of which the color of the sky becomes whitish. With a whitish sky or in the presence of a weak fog, the total intensity of scattered radiation increases by 1.5-2 times.

When clouds appear, the intensity of scattered radiation increases even more. Its value is closely related to the amount, shape and location of clouds. So, if at a high standing of the sun the sky is covered by clouds by 50-60%, then the intensity of scattered solar radiation reaches values ​​equal to the flow of direct solar radiation. With a further increase in cloudiness and especially with its compaction, the intensity decreases. With cumulonimbus clouds, it can even be lower than with a cloudless sky.

It should be borne in mind that if the flow of scattered radiation is higher, the lower the transparency of the air, then the intensity of ultraviolet rays in this type of radiation is directly proportional to the transparency of the air. In the daily course of changes in illumination, the greatest value of scattered ultraviolet radiation falls on the middle of the day, and in the annual course - in winter.

The value of the total flux of scattered radiation is also influenced by the energy of the rays reflected from the earth's surface. So, in the presence of pure snow cover, scattered radiation increases by 1.5-2 times.

The intensity of reflected solar radiation depends on physical properties surface and from the angle of incidence of sunlight. Wet black soil reflects only 5% of the rays falling on it. This is because the reflectivity decreases significantly with increasing soil moisture and roughness. But alpine meadows reflect 26%, polluted glaciers - 30%, clean glaciers and snowy surfaces - 60-70%, and freshly fallen snow - 80-90% of the incident rays. Thus, when moving in the highlands along snow-covered glaciers, a person is affected by a reflected stream, which is almost equal to direct solar radiation.

The reflectivity of individual rays included in the spectrum of sunlight is not the same and depends on the properties of the earth's surface. So, water practically does not reflect ultraviolet rays. The reflection of the latter from the grass is only 2-4%. At the same time, for freshly fallen snow, the reflection maximum is shifted to the short-wavelength range (ultraviolet rays). You should know that the number of ultraviolet rays reflected from the earth's surface, the greater, the brighter this surface. It is interesting to note that the reflectivity of human skin for ultraviolet rays is on average 1-3%, that is, 97-99% of these rays falling on the skin are absorbed by it.

Under normal conditions, a person is faced not with one of the listed types of radiation (direct, diffuse or reflected), but with their total effect. On the plain, this total exposure under certain conditions can be more than twice the intensity of exposure to direct sunlight. When traveling in the mountains at medium altitudes, the irradiation intensity as a whole can be 3.5-4 times, and at an altitude of 5000-6000 m 5-5.5 times higher than normal flat conditions.

As has already been shown, with increasing altitude, the total flux of ultraviolet rays especially increases. At high altitudes, their intensity can reach values ​​exceeding the intensity of ultraviolet irradiation with direct solar radiation in plain conditions by 8-10 times!

Influencing open areas of the human body, ultraviolet rays penetrate the human skin to a depth of only 0.05 to 0.5 mm, causing, at moderate doses of radiation, redness, and then darkening (sunburn) of the skin. In the mountains, open areas of the body are exposed to solar radiation throughout the daylight hours. Therefore, if the necessary measures are not taken in advance to protect these areas, a body burn can easily occur.

Outwardly, the first signs of burns associated with solar radiation do not correspond to the degree of damage. This degree comes to light a little later. According to the nature of the lesion, burns are generally divided into four degrees. For the considered sunburns, in which only the upper layers of the skin are affected, only the first two (the mildest) degrees are inherent.

I - the mildest degree of burn, characterized by reddening of the skin in the burn area, swelling, burning, pain and some development of skin inflammation. Inflammatory phenomena pass quickly (after 3-5 days). Pigmentation remains in the burn area, sometimes peeling of the skin is observed.

II degree is characterized by a more pronounced inflammatory reaction: intense reddening of the skin and exfoliation of the epidermis with the formation of blisters filled with a clear or slightly cloudy liquid. Full recovery of all layers of the skin occurs in 8-12 days.

Burns of the 1st degree are treated by skin tanning: the burnt areas are moistened with alcohol, a solution of potassium permanganate. In the treatment of second degree burns, the primary treatment of the burn site is performed: rubbing with gasoline or 0.5%. ammonia solution, irrigation of the burnt area with antibiotic solutions. Considering the possibility of introducing an infection in field conditions, it is better to close the burn area with an aseptic bandage. A rare change of dressing contributes to the speedy recovery of the affected cells, since the layer of delicate young skin is not injured.

During a mountain or ski trip, the neck, earlobes, face and skin of the outer side of the hands suffer most from exposure to direct sunlight. As a result of exposure to scattered, and when moving through the snow and reflected rays, the chin, lower part of the nose, lips, skin under the knees are burned. Thus, almost any open area of ​​the human body is prone to burns. On warm spring days, when driving in the highlands, especially in the first period, when the body is not yet tanned, in no case should one allow a long (over 30 minutes) exposure to the sun without a shirt. gentle skin abdomen, lower back and lateral surfaces chest most sensitive to ultraviolet rays. It is necessary to strive to ensure that in sunny weather, especially in the middle of the day, all parts of the body are protected from exposure to all types of sunlight. In the future, with repeated repeated exposure to ultraviolet radiation, the skin acquires a tan and becomes less sensitive to these rays.

The skin of the hands and face is the least susceptible to UV rays.

Rice. 7

But due to the fact that it is the face and hands that are the most open parts of the body, they suffer most from sunburn. Therefore, in sunny days face should be protected with a gauze bandage. In order to prevent the gauze from getting into the mouth during deep breathing, it is advisable to use a piece of wire (length 20-25 cm, diameter 3 mm), passed through the bottom of the bandage and curved in an arc (rice. 7).

In the absence of a mask, the parts of the face that are most susceptible to burns can be covered with a protective cream such as "Ray" or "Nivea", and lips with colorless lipstick. To protect the neck, it is recommended to hem double-folded gauze to the headgear from the back of the head. Take special care of your shoulders and hands. If with a burn

shoulders, the injured participant cannot carry a backpack and all his load falls on other comrades with an additional weight, then in case of a burn of the hands, the victim will not be able to provide reliable insurance. Therefore, on sunny days, wearing a long-sleeved shirt is a must. The back of the hands (when moving without gloves) must be covered with a layer of protective cream.

snow blindness

(eye burn) occurs with a relatively short (within 1-2 hours) movement in the snow on a sunny day without goggles as a result of a significant intensity of ultraviolet rays in the mountains. These rays affect the cornea and conjunctiva of the eyes, causing them to burn. Within a few hours, pain (“sand”) and lacrimation appear in the eyes. The victim cannot look at light, even at a lit match (photophobia). Some swelling of the mucous membrane is observed, later blindness may occur, which, if measures are taken in a timely manner, disappears without a trace after 4-7 days.

To protect your eyes from burns, you must use goggles, dark glasses of which (orange, dark purple, dark green or Brown color) to a large extent absorb ultraviolet rays and reduce the overall illumination of the area, preventing eye fatigue. It is useful to know that the color orange improves the feeling of relief in conditions of snowfall or light fog, creates the illusion of sunlight. Green color brightens up the contrasts between brightly lit and shady areas of the area. Because bright sunlight, reflected from a white snowy surface, has a strong stimulating effect on the nervous system through the eyes, then wearing goggles with green lenses has a calming effect.

The use of goggles made of organic glass in high-altitude and ski trips is not recommended, since the spectrum of the absorbed part of the ultraviolet rays of such glass is much narrower, and some of these rays, which have the shortest wavelength and have the greatest physiological effect, still reach the eyes. Prolonged exposure to such, even a reduced amount of ultraviolet rays, can eventually lead to eye burns.

It is also not recommended to take canned glasses that fit snugly to the face on a hike. Not only glasses, but also the skin of the part of the face covered by them fogs up a lot, causing an unpleasant sensation. Much better is the use of conventional glasses with sidewalls made of a wide adhesive plaster. (Fig. 8).

Rice. eight.

Participants in long hikes in the mountains must always have spare glasses at the rate of one pair for three people. In the absence of spare glasses, you can temporarily use a gauze blindfold or put cardboard tape over your eyes, making pre-narrow slits in it in order to see only a limited area of ​​\u200b\u200bthe area.

First aid for snow blindness: rest for the eyes (dark bandage), washing the eyes with a 2% solution of boric acid, cold lotions from tea broth.

Sunstroke

A severe painful condition that suddenly arises during long transitions as a result of many hours of exposure to infrared rays of direct sunlight on an uncovered head. At the same time, in the conditions of the campaign, the back of the head is exposed to the greatest influence of the rays. The outflow of arterial blood that occurs in this case and a sharp stagnation of venous blood in the veins of the brain lead to its edema and loss of consciousness.

The symptoms of this disease, as well as the actions of the first aid team, are the same as those for heat stroke.

A headgear that protects the head from exposure to sunlight and, in addition, retains the possibility of heat exchange with the surrounding air (ventilation) thanks to a mesh or a series of holes, is a mandatory accessory for a participant in a mountain trip.

Just don't kick!

Based on the “Vertical Limit” I watched the other day: there people in the mountains were dying from pulmonary edema. And for some reason they had to drink in without fail. Something like "a cup every two hours." What for?

Answered: 16

The basis for the formation of pulmonary edema at altitude is, as a rule, the phenomenon of increased permeability of the walls of the pulmonary capillaries and alveoli, as a result of which foreign substances (protein masses, blood elements and microbes) penetrate into the alveoli of the lungs. Therefore, the useful capacity of the lungs is sharply reduced in a short time. Hemoglobin of arterial blood, washing the outer surface of the alveoli, filled not with air, but with protein masses and blood elements, cannot be adequately saturated with oxygen. As a result, from insufficient (below the permissible norm) supply of oxygen to body tissues, a person quickly dies.

mountain sickness

The name itself "mountain sickness" already suggests that this disease develops in people at high altitudes.

Why is this happening?

As the height increases the body stops getting the required amount of oxygen. This is not only because there is less oxygen at altitude. It's all about low air pressure and a correspondingly reduced oxygen pressure, which is why the blood flowing through the lungs does not have time to capture enough this gas. At sea level, the blood is 95% oxygenated. At an altitude of 8.5 km. saturation drops to 71%.

You don't have to be a professional rock climber or alpine skier to get altitude sickness. Any person who travels - by plane, car, bicycle, cable car or just in hiking boots, having climbed to a height 1000m or above above sea level is at risk of this problem. Moreover, sometimes these travelers, who are not accustomed to high altitudes, develop an extremely severe, acute form of altitude sickness - high-altitude pulmonary edema, i.e., a potentially fatal accumulation of fluid in the lungs.

Mountain sickness can affect young and old, male and female, trained and untrained, novice and veteran high-altitude climbers. If you are planning to climb to the top, you just need to take some precautionary measures. to avoid serious problems with health lying in wait for you in the mountains at an altitude of more than 2.5 km.

Some people quickly adapt to a lack of oxygen, but others do not succeed. Mountain sickness can happen to anyone. Usually, people adjust to an altitude of 3000m within a few days, but acclimatization to higher altitudes can take several weeks.

What are the symptoms of altitude sickness?

If you experience shortness of breath, nausea and headache when climbing mountains, know that these are the first symptoms of the disease. Taking plenty of fluids and analgesics will help. More severe complications of altitude sickness can include:

• pulmonary edema- a dangerous condition in which a large amount of fluid accumulates in the lungs;
• cerebral edema. which develops 24-96 hours after climbing to a high altitude, and the symptoms resemble alcohol intoxication;
• retinal hemorrhage. which may be accompanied by the appearance of a small blind spot in the field of view.

For such complications, immediately lower the patient from a height. and before descending, the patient is advised to take a dexamethasone tablet. The patient needs bed rest, while he should be in a semi-sitting position.

By the way, people who constantly live at altitude develop chronic mountain sickness. which is very often manifested by heart failure. In this case, nitroglycerin is effective. However, not everyone can live on top!

The intensity of the development of mountain sickness depending on the height

altitude sickness

1. Acute mountain sickness

2. Pulmonary edema occurring at high altitudes

3. Cerebral edema at high altitudes

4. Acclimatization

Literature

Introduction

First post about acute development altitude sickness was made by the Chinese Too-Kin between 37 and 32 BC. The author warned of such an illness, which he experienced while climbing the 4827 m high Kilik Pass in Afghanistan. Early reports of altitude sickness include its description in 1590 by the Jesuit priest José de Acosta, who lived for about 40 years at an altitude of 5334 m in the Peruvian Andes. Altitude sickness cases lethal outcome were first recorded in 1875 when two French aeronauts died at an altitude of 8534 m. There are now more than 100,000 active climbers in the United States. Many mountain climbers are completely uninformed or have little idea medical aspects the dangers of high altitudes. These factors, combined with air travel and strong competition among climbers, have contributed to a rapid increase in the incidence of altitude sickness and other diseases associated with climbing to high altitudes.

The effect of low atmospheric pressure occurring at high altitudes can be felt in the following cases: when climbing uphill; when flying in an airplane or space aircraft, balloon and glider; in a pressure chamber (with low pressure or vacuum). The health hazards associated with such exposure fall into two categories: high altitude complications (decrease in barometric pressure and low oxygen content in the surrounding air); complications associated with adverse impact environment, such as cold, dampness, avalanches, lightning, ultraviolet radiation, etc. Altitude sickness sufferers often have accompanying illnesses- hypothermia, frostbite, traumatic injuries and deep damage due to ultraviolet radiation.

The reading of high altitudes usually begins with a mark of more than 2438 m above sea level. In the US, climbing above this mark is rare. Accurate and complete data on the pathophysiological changes caused by hypoxia at high altitude are not available. In this case, one of the main violations, apparently, is a failure, depending on the adenosine triphosphate (ATP) sodium pump, which normally maintains cellular osmolar balance. Inadequate ATP production due to reduced oxidative cellular respiration prevents the maintenance of a sodium gradient inside and outside the cell. This may contribute to generalized edema associated with altitude disturbances. Hypoxia also induces changes in the secretion of antidiuretic hormone, growth hormone and other humoral regulators.

As altitude increases, barometric pressure decreases so that climbers breathe air with a low partial pressure of oxygen (oxygen percentage remains relatively constant). At an altitude of 5486 m, the partial pressure of oxygen is half its value at sea level. Oxygen transport is due to sufficient saturation of arterial blood, which does not decrease significantly until the altitude is from 2743 to 3048 m. During exercise, this occurs earlier. The decrease in oxygen supply is the trigger of the carotid glomus reflex, which causes hyperventilation, partially compensating for the decrease in oxygen supply. Physical activity is accompanied by a drop in Ra 02. since the diffuse capacity of the pulmonary capillaries cannot be at the same level as the accelerated pulmonary blood flow. Sleep at high altitude is characterized by severe hypoventilation with significant periods of deoxygenated arterial blood. Sedatives used to promote sleep at high altitudes can exacerbate respiratory hypoxia.

The body's hypoxic ventilatory response is variable and may be a major contributing factor to the development of severe altitude sickness. Individuals not stimulated by hypoxia to hyperventilate may have more profound changes when periodic breathing and tolerate longer periods of hypoxemia, which contributes to damage to the vascular membrane and the onset of pulmonary hypertension. Endurance athletes who are practically unresponsive to respiratory hypoxia at sea level are prone to developing pulmonary edema at high altitudes.

With a rapid ascent to a high altitude, an increase in urine output causes a decrease in plasma volume, which contributes to the deterioration of many indicators of homeostasis. The already existing dehydration is further facilitated by inadequate fluid intake along with an increase in its loss when breathing cold and dry mountain air.

1. Acute mountain sickness

Acute mountain sickness (AMS) is the most commonly observed altitude sickness. This self-limiting disease occurs due to rapid ascent to high altitudes in non-acclimatized individuals. ASD occurs in 20–30% of persons ascending to a height of 2438 to 2743 m in at least 24–48 hours, and in almost all ascenders (without long stops) to heights of more than 3353 m. Almost 45% of tourists ascending in the Khumbu valley in eastern Nepal, to overlook Mount Everest, the OGB is developing; 1% of them develop severe pulmonary or cerebral edema. Colorado skiers have an AMS rate of 15-17%, Mt. McKinley climbers have an AMS rate of 50% (3% of them develop pulmonary or cerebral edema), and Mt. Rainier climbers have an AMS rate of 70%. Among the latter, pulmonary or cerebral edema rarely occurs, which is most likely due to the fact that the descent from this mountain is less difficult and all base camps are located below 2896 m, so tourists spend the night in more favorable conditions at a lower height. A clear relationship between the occurrence of AMS and the initial physical condition or gender was not noted.

Most frequent symptoms diseases are headache, loss of appetite, nausea, vomiting, irritability, insomnia, shortness of breath on exertion and fatigue. Headache is associated with subacute edema brain or with the occurrence of spasm or vasodilation of the brain due to hypocapnia or hypoxia (respectively). Other symptoms described include general weakness, fatigue, shortness of breath, dizziness, memory impairment, reduced ability to concentrate, palpitations, tachycardia, chest pain, tinnitus, and oliguria. Sleep disturbance due to headache and the appearance of Cheyne-Stokes respiration (occurs in almost everyone at an altitude of more than 2743 m) can be of particular concern and contribute to the development of cerebral edema during hypoxia. In all likelihood, many victims of altitude sickness have a subclinical form of high-altitude pulmonary edema.

In susceptible individuals, symptoms usually begin 4–6 hours after ascent to high altitude, reach their maximum severity after 24–48 hours, and then gradually subside (over 3–4 days). However, in some cases, the symptoms of AMS go unnoticed in the first 18 to 24 hours or may persist for more than 5 days.

Despite moderate weakness, the development of mountain sickness is not an indication for evacuation or specific pharmacotherapy. Symptoms usually worsen with increased physical activity. Some relief is achieved by minimizing physical activity, abstaining from alcohol, increasing fluid intake to ensure adequate hydration, taking light write, the introduction of a diet with a predominant content of carbohydrates, as well as quitting smoking. Headache can be relieved with aspirin or codeine; in case of severe pain, additional oxygen breathing is necessary. Nausea and vomiting are usually treated with the antiemetic drug prochlorperazine (Compazine), which is also a mild respiratory stimulant. Sleep disturbance can be reduced by continuous inhalation of oxygen during sleep. AMS may be a precursor to other, more serious forms of altitude sickness.

The final treatment option is to descend from the mountains. It may be sufficient to reduce the height to 305 m; the victim must be moved to a height that is optimal for achieving his normal condition.

The best way to prevent AMS is to acclimatize by gradually climbing mountains or staying at the altitude for a few days. However, if compliance with this recommendation is impossible or it is deliberately neglected, then the appointment of an inhibitor of carbonic anhydrase acetazolamide (diamox) helps to improve the condition or completely prevent the disease. Acetazolamide is taken 125-250 mg every 8-12 hours 1 day before the ascent, on the way and within 1-2 days after the ascent. In case of recurrence of symptoms, it can also be used directly during movement. Although the use of this drug cannot completely prevent AMS, it can eliminate intermittent respiratory disorders. Commonly observed side effects include paresthesia of the lips and extremities, fatigue, and frequent urination. The appointment of acetazolamide does not exclude the need for rapid descent of the victims in the event of a more severe development of acute mountain sickness. With moderate severity of AGB, weak sedatives. Triazolam (Halcyone), a benzodiazepine derivative with a serum half-life of 23 hours, is a short-acting oral 0.25–0.5 mg dose ideal for use at high altitude. Drug use should be avoided.

In his work, Hackett suggested that dexamethasone (decadron) could prevent altitude sickness in people with mild physical activity but not in well-trained subjects. If dexamethasone is stopped before acclimatization, then AMS is very likely to develop. Dexamethasone, taken at 4 mg every 6 hours, is effective in the treatment of the form of the disease that occurs with neurological disorders. This drug has not been proven to be better than acetazolamide, or that a combination of two drugs is better than giving one of them.

2. Pulmonary edema occurring at high altitudes

High-altitude pulmonary edema was first described in 1891 by Charles Houston in 1960. He was the first to provide a complete scientific description of this non-cardiogenic pulmonary edema that occurs in non-acclimatized individuals rapidly ascending to altitudes above 2286 m. Its incidence reaches 0, 6%. He currently represents real danger for mountain climbers.

Although the exact pathophysiological changes have not been fully described, pulmonary edema is likely due in part to an increase in intracranial pressure. pulmonary artery, which seems to be the body's first response to hypoxia. This may serve as a trigger for the release of leukotrienes, which increase the permeability of the pulmonary arterioles, and, consequently, the leakage of fluid into the extravascular space. Consistent with this hypothesis is the observation that severe pulmonary edema develops at relatively low altitudes in a number of apparently healthy individuals with congenital unilateral absence of the pulmonary artery or atresia. This rare anomaly is associated with pulmonary hypertension, which increases even at low altitudes. Further studies should elucidate whether hypoxic contraction of the microvascular bed of the pulmonary artery is accompanied by intravascular thrombosis or whether the loss of fluid from the vessel occurs proximal to the area of ​​vascular spasm. Research of cellular and biochemical composition bronchoalveolar fluid with pulmonary edema made it possible to establish a significant increase in its protein with a high molecular weight, erythrocytes and macrophages without accumulation of particles or components of collagen on the basement membrane.

The first symptoms usually appear 24 to 72 hours after reaching high altitude, often preceded by significant physical activity. Particularly susceptible to pulmonary edema are children and adolescents who are at high altitude for a long time, for whom it is advisable to alternate lifting to a height with a temporary movement to a lower level.

The first symptoms are usually shallow breathing, non-productive cough, headache, weakness and fatigue, in particular a decrease in exercise tolerance. With a mild disease, the duration of its manifestation does not exceed 24 hours. may be present concomitant symptoms AMS, which are especially common in children. As pulmonary edema increases, dyspnea and cough appear, which may be accompanied by frothy and bloody sputum. The symptoms are often aggravated dramatically during sleep. General weakness, lethargy, disorientation, hallucinations, stupor, and coma may occur. Individuals with severe ataxia are more likely to go into coma within 6 to 12 hours. If the victim does not move to a lower altitude, then death may occur quickly.

Typical physical signs include hyperpnea, wheezing, tachycardia, and cyanosis. Hypotension may be present and slight increase body temperature, but orthopnea is rare. Laboratory tests may reveal signs of dehydration and hemoconcentration (eg, increased hematocrit and urine specific gravity). On a chest x-ray, patchy opacities can be seen around the periphery of the lung fields, which is different from the pattern of edema in the root zones of the lungs, which is observed in congestive heart failure. In the presence of pulmonary edema on one side, one can think of unilateral pulmonary atresia. The ECG reveals signs of myocardial ischemia, deviation of the axis of the heart to the right, or expansion of the right ventricle. For clinical assessment The severity of pulmonary edema is proposed to be divided into four degrees.

Adequate treatment is based on the rapid recognition of pathology. Failure to take medical measures immediately after diagnosis can lead to the death of the victim. Mortality in some series of observations is about 12%. Depending on the severity of the symptoms, the basis of treatment is complete rest, administration of oxygen and descent to a lower altitude. In mild cases, compliance with bed rest, but with more serious manifestations of the disease, the descent of the victim to a lower height is mandatory. Indeed, altitude reduction is the only effective treatment for severe forms of pulmonary edema, so descent should never be delayed in patients with threatening symptoms illness. Descent to a height of 610 m can lead to an improvement in the patient's condition, since at this level the oxygen concentration in the inhaled air increases significantly, which ensures an increase in the oxygen saturation of arterial blood. None of the victims should go down unaccompanied. If the victim has mental disorders or severe ataxia, then his evacuation must be carried out on a stretcher or using a helicopter. Oxygen is introduced at 6–8 l/min. An effective supportive measure could be artificial ventilation with positive pressure, but it is only recommended for patients with profound pulmonary edema.

Intravenous fluid replacement with a solution containing D,/0.25 N NaCl is reasonable, as is salt restriction, but the use of furosemide and other diuretics is of limited value. Although the effectiveness of morphine in the treatment of pulmonary edema has not been proven, its reasonable use is recommended by some doctors involved in the treatment of altitude sickness. The use of acetazolamide is associated with a temporary improvement and subsequent rebound phenomenon.

Since the occurrence of pulmonary edema is closely related to the rate of ascent, the height achieved and the energy expended, acclimatization is the most effective way to prevent it.

3. Cerebral edema at high altitudes

Cerebral edema that occurs at high altitudes (sometimes called high-altitude encephalopathy) is the most severe form of acute altitude sickness; it was not actually recognized until 1959. Fortunately, serious cases of high-altitude cerebral edema (HACE) are rare, almost always at altitudes above 3658 m, although there are reports of its occurrence at altitudes below 2438 m. e. whether it develops as a result of cerebral vasodilation, increased cerebral blood flow in the absence of microcirculation protection, or as a result of a defect in the ATP-mediated sodium-potassium pump. It can be assumed that subclinical cerebral edema is more widespread than previously thought. Unlike altitude sickness and pulmonary edema, which have no long-term consequences, HCM can cause permanent neurological damage.

Cerebral edema can be accompanied by a variety of neurological manifestations, although it hallmark is a severe headache. Ataxia and clumsiness of gait are often observed, most likely due to the sensitivity of the cerebellum to hypoxia. Ataxia (manifested by the inability to walk clearly in a straight line) is a sure indicator of incipient HCM. Unfortunately, cerebellar symptoms are often initially associated with hypothermia, walking on uneven terrain, or other environmental factors. As HCM progresses, other symptoms appear, including confusion, irritability, emotional lability, auditory and visual hallucinations. Paranoia and irrational thinking can lead to threatening behavior. The mind and physical dexterity of the victim deteriorate, which makes it impossible for him to perform the necessary mental and physical tasks. If urgent treatment is not started, the rapid progression of HCM leads to lethargy, stupor, coma and death.

Obvious manifestations of HCM also include nausea, vomiting, papilledema, retinal vein congestion, and muscle weakness. Deep tendon reflexes usually persist until coma develops; in advanced cases, a spasmodic or decerebral posture of the body may be observed. Despite increased pressure cerebrospinal fluid meningeal symptoms are rare. Urinary incontinence or urinary retention may also occur.

Treatment of cerebral edema should be urgent and clear. It should be started at the first manifestations of ataxia or changes in the psyche. Be sure to lower the victim to a lower height. As experience has shown recent years, administration of corticosteroids (dexamethasone, 4 mg PO, IM or IV every 4 to 6 hours) leads to dramatic improvement and can be used prophylactically. It is necessary to provide breathing with a large flow of oxygen and give the head of the victim an elevated position. The feasibility of using osmodiuretics has not been proven. Sufficient acclimatization is essential to prevent this potentially fatal complication occurring at high altitudes.

4. Acclimatization

Most effective way to avoid the occurrence of acute mountain sickness, pulmonary edema or cerebral edema is sufficient acclimatization. It is achieved by limiting the ascent rate to 456 m per day to a height of more than 2438 m with a rest for 1 day after each day of ascent. The most experienced climbers "climb high and sleep low", ie. they, rising 152–244 m above the camp during the day, choose the lowest point of altitude for sleep, which contributes to the process of acclimatization. Where possible, significant physical exertion should be avoided for 2 to 4 days after reaching a new, higher altitude. First day on new height should be a rest day. If used for lifting modern facilities movement (especially helicopters), the first height should not exceed 2438 m; and in this case the first day should be devoted to rest.

Hyperventilation, partly determined by the hypoxic ventilatory response, causes a decrease in P CO2 and the development of respiratory alkalosis, which is compensated by the excretion of sodium bicarbonate by the kidneys. Arterial blood pH consistently normalizes within 10–14 days. is increasing cardiac output due to the increase in heart rate. The amount of intracellular fluid increases, there is a concomitant increase in diuresis due to venoconstriction and central displacement of blood volume. The increase in hemoglobin concentration is explained by a decrease in plasma volume. As a rule, there is an initial increase in cerebral blood flow. At high altitude, osmoregulation deteriorates, leading to a state of hyperosmolarity without a corresponding arginine–vasopressin response.

Although the initial physical parameters may indicate the reliability of the body, this, however, does not prevent the development of altitude sickness. Intermittent exposure does not give a sufficient effect, and in persons descending to a height below 2438 m, acclimatization is lost in 7–14 days. Pharmacological agents cannot replace appropriate acclimatization. During the acclimatization period, medications that suppress the respiratory response to hypoxia should be avoided; this group includes alcohol, benzodiazepines, antihistamines and barbiturates.

Administration of acetazolamide (at a dose of 250 mg po every 12 hours) is the most effective adjunct to acclimatization. The drug is started on the day of ascent and continued for 2-4 days. It suppresses the dissociation of carbon dioxide, causing its accumulation; however, it increases the excretion of sodium and potassium bicarbonate in the urine, which creates the conditions for metabolic acidosis. Stimulation of respiration and ventilatory gas exchange can be carried out by increasing the sensitivity to oxygen of peripheral chemoreceptors and stimulating the chemoreceptors of the central nervous system with a decrease in alkali inhibition. Carbonic diuresis suggests normal renal adaptation to respiratory alkalosis, including hyperventilation at altitude, which promotes acclimatization. Acetazolamide does not appear to increase cerebral blood flow, although it does inhibit CSF production and cause a moderate decrease in CSF pressure. The drug is a derivative of sulfur and should not be administered during pregnancy.

5. Retinopathy occurring at high altitudes

Spontaneous retinal hemorrhage and others vascular changes may occur at an altitude of 3658 m, although they usually occur when climbing to higher altitudes. High-altitude retinopathy (AR) can occur both as an independent phenomenon and in combination with other forms of acute altitude sickness (especially with pulmonary and cerebral edema), but it rarely occurs with simple mountain sickness. At an altitude of more than 3658 m, it is stated in 40% of cases. The retinal response to high altitudes includes vascular congestion and optic disc hyperemia.

Although VR is usually asymptomatic, victims may complain of blurred vision. If there is a hemorrhage in the yellow spot, then the appearance of central cattle is not excluded. Ophthalmoscopy reveals multiple and often bilateral hemorrhages, shaped like a flame; in addition, hyperemia of the disc is noted, as well as expansion and tortuosity of the retinal vessels. The study of blood flow in the retina made it possible to establish its significant increase in comparison with normal conditions. The prerequisites for the occurrence of retinal hemorrhages at high altitude are increased pressure in the retinal capillaries, hyperemia of the optic nerve head, changes in capillary permeability, increased venous pressure during exercise, and poor acclimatization. The significance of VR is unclear as these hemorrhages tend to be self-limiting and usually resolve without sequelae within a few weeks of descent from altitude. However, persistent central scotomas may remain after patchy hemorrhages.

The use of acetazolamide does not prevent VR; given state usually not considered significant enough to warrant descent unless the hemorrhage involves the macula and impairs central vision. specific treatment high-altitude retinopathy currently does not exist, as well as reliable data on its prevention.

6. Increasing outgassing at high altitudes

Increased gas discharge appears at an altitude of more than 3353 m. It is associated with the expansion of gases in the lumen of the colon with a decrease in atmospheric pressure, a decrease in the contractility of the intestine due to hypoxia, malabsorption and the use of a diet that promotes the formation of gases. This disorder can be reduced by oral administration of enzymes or simethicone.

7. Various acute complications at high altitudes

At high altitude, one has to face various other problems and complications. For example, deep vein thrombosis and other manifestations of vascular thromboembolism are well-known complications of prolonged passive exposure to high altitude, which are exacerbated by dehydration and hypoxia-induced polycythemia. Due to the problems associated with the use of anticoagulants, almost the only treatment in this situation is acetylsalicylic acid.

Changes in the larynx that occur at high altitude are due to breathing through the mouth, hyperventilation and inhalation of cold and dry air in alpine conditions. Dryness and swelling of the mucous membrane of the larynx appear, but the body temperature does not rise, there is no exudation or adenopathy, which makes it possible to exclude the presence of infection. Some relief comes from constantly drinking fluids in small sips, gargling with solutions of soda or salt, and taking pills that stimulate salivation. You should not resort to local anesthetics, as this can miss the development of a bacterial infection.

Mild to moderate swelling of the face, hands, and feet may develop, especially in women. This is due to the retention of sodium and water in the body with a decrease in plasma volume, which occurs at high altitude. Diuretics may be used, but their administration must be accompanied by sufficient fluid intake to avoid dehydration and electrolyte imbalance. Sodium retention may be helpful. Usually self-healing occurs, the resulting deviations are resolved shortly after returning to a lower altitude.

A rare problem that can occur when suddenly exposed to low barometric pressure above 18,288 m is ebullism. This is the formation of water vapor bubbles in the body. This phenomenon is not associated with mountain climbing, but rather is related to aerospace medicine and has been described in industrial accidents in connection with the operation of vacuum chambers. Kolesari and Kindwall reported the successful recompression of a person who was accidentally decompressed in an industrial vacuum chamber at a pressure equivalent to that at 22,555 m for more than 1 minute. Of all the human high-altitude decompression incidents ever described, this was the most severe, but not fatal.

The reduced barometric pressure present at high altitude adversely affects a number of conditions and diseases; these include, for example, primary pulmonary hypertension, cyanotic congenital heart disease, chronic lung disease, ischemic heart disease, congestive heart failure, and sickle cell anemia. Individuals with S-S and S-C haemoglobinopathies and S-p-thalassemia should avoid exposure to low barometric pressure. In blacks presenting at high altitude with complaints of chest, back, or abdominal pain, shallow breathing, or arthralgia, the condition must first be differentiated from sickle cell anemia. The syndrome of enlargement of the spleen in persons of the white race during travel and holidays in the mountains is described.

On the "high-altitude" pharmacological properties of most drugs commonly used in these and other chronic diseases, very little is known. The possibility of using military anti-shock trousers in OGB has been proven, which changes approaches to high altitude.

9. Chronic altitude sickness

Subacute mountain sickness is diagnosed when suddenly occurring symptoms of the disease do not disappear within 3-4 days, but persist for several weeks or months, causing noticeable weight loss, insomnia, mental and physical depression. it rare disease can be cured by descending to a lower altitude.

Prolonged stay at high altitude can lead to the development of chronic mountain sickness, which manifests itself muscle weakness, increased fatigue, drowsiness and confusion.

On examination, cyanosis, plethora, and thickening of the terminal phalanges of the fingers are found; more detailed examination may reveal polycythemia, hypoxemia, pulmonary hypertension, and right ventricular failure. The causative factor of these changes, apparently, is chronic alveolar hypoventilation due to the weakening of the respiratory response to hypoxia. All symptoms and signs disappear after the patient returns to a lower altitude. Older migrants who have left their homes in the mountains are more likely to develop heart and lung diseases than those who permanently live at high altitudes. Treatment includes phlebotomy and a respiratory stimulant (medroxyprogesterone acetate), which improves ventilation and oxygenation during sleep.

Unlike chronic mountain sickness, polycythemia (only) can develop as a result of chronic hypoxemia associated with living at high altitude.

For persons living at an altitude of more than 3658 m, an increase in hematocrit is characteristic (from moderate to 50%).

In addition, people who permanently live at high altitudes often have a moderate degree of pulmonary hypertension. Most likely, this is due to increased pulmonary vasoconstriction in response to hypoxia; unlike primary pulmonary hypertension, which occurs in people living at sea level, high-altitude pulmonary hypertension is characterized by a benign course and is quite reversible upon return to a lower altitude.

Literature

1. Emergency medical care: Per. from English. / Ed. J.E. Tintinalli, R.L. Crouma, E. Ruiz. - M. Medicine, 2001.

2. Internal diseases Eliseev, 1999