How does altitude affect pressure levels? Prevention of mountain sickness. Preventing altitude sickness

As soon as a person climbs the mountains and overcomes a certain altitude barrier (usually from 2500 m above sea level), he is faced with reduced atmospheric pressure and reduced oxygen content. Once in such a hostile environment, the body begins to adapt to what is happening. The process is accompanied by a deterioration in well-being and a painful condition. It's called altitude sickness, and the period while the body adapts to high altitudes is acclimatization.

Essentially mountain sickness is high-altitude hypoxia, which is aggravated by physical activity and harsh conditions external environment in the mountains: physical stress, cold, limited nutrition, high humidity.

As you gain altitude, each breath contains less and less oxygen. With increasing physical activity in the mountains, the body's need for oxygen further increases. During the process of acclimatization, the human body tries to adapt, and the following arise:

• rapid breathing, increasing gas exchange in the lungs;
• the number of red blood cells increases and the blood transports large quantity oxygen;
• the heart rate increases and blood pressure increases, the flow of arterial blood to the brain and muscles.

Changes in metabolic processes and blood composition are actually acclimatization. The main acclimatization occurs in the first 2-3 days in the mountains. After this, a person can get by with less oxygen in the air and spend energy more efficiently.

The occurrence of altitude sickness is influenced not only by altitude, but also by a number of other environmental factors:

Environmental factors that provoke miner

Coldand inhumidity forced to inhale frequently and in small portions, increasing hypoxia. In addition, with hypothermia, edema also occurs, as with high-altitude edema of the lungs and brain, which significantly reduces the compensatory capabilities of the body.

Wind hurricane force seriously impairs breathing and increases hypothermia.

In the cold humid climate Symptoms of altitude sickness will appear at lower altitudes than in dry and warm conditions.💧 In Kamchatka and Patagonia, altitude sickness manifests itself already at an altitude of 1000-1500 m above sea level. ur. m. In the Alps - from 2500 m, in the Caucasus from 3000 m, in the Andes from 4000 m. ☀For comparison, let's take mountains in a dry continental climate: nand in the Tien Shan the “miner catches” at 3500 m, in the Pamirs from 4500 m, in the Himalayas it spares up to 5000 m.

"Death Zone"

If averaged, then at an altitude of 3500 meters there are unpleasant symptoms. Above 4500 meters, regardless of a person’s physical fitness, Negative consequences influence of altitude. When exceeding 6500 meters, acclimatization does not occur; this altitude is called "death zone".

While the body is undergoing restructuring, the person suffers from hypoxia. Brain cells are especially susceptible to lack of oxygen. It is for this reason that headaches are so common among climbers.

What affects the symptoms of mountain sickness?

ANDindividual characteristics of the body. People who were born/lived in the mountains tolerate heights much better. A striking example of this is the Sherpas in Nepal, who, without oxygen cylinders They carry almost all the things of climbers and expeditions, and sometimes even the climbers themselves, to Everest and beyond:).

Among the inhabitants of the plains (like you and me) there are also organisms that are more or less resistant to altitude. But this stability can only be tested in the field.

Age. It is well known that what older man, the easier he tolerates the “miner”. Most likely this is due to general decline oxygen needs.

Floor. It is believed that it is more difficult for men to adapt to high altitude conditions, while women are generally more stress-resistant and more easily “switch” to efficient energy consumption.

General condition of the body. The matter is especially aggravated by chronic or acute diseases respiratory tract, problems with the liver, spleen and kidneys, diabetes.

« INhigh altitude experience relieves symptoms, although is not a determining factor. For example, an experienced climber with bronchitis will tolerate heights much worse than a healthy beginner.

Psychological stability. Experienced climbers compare mountain sickness to alcohol intoxication, only very strong and prolonged. Based on this, many can imagine what awaits in the High Mountains :). Only there is no salvation or cure for this. You'll have to be patient and positive attitude will be very useful.

External factors

Dialing speed height. It’s clear here: the faster we rise, the worse it will be. You need to give yourself time to rebuild and adapt.

Physical effort during the ascent. Muscles need oxygen to work, which is already insufficient. The more blood goes to the muscles, the less there is for everything else. Because of excessive load Pulmonary or cerebral edema can easily develop (extreme forms of mountain sickness, which we will discuss below).

Time spent at altitude. If adaptation proceeds correctly, then in 2-4 days your health will be closer to normal. However, mountaineering complications signal that the body cannot cope with acclimatization and every hour spent at altitude aggravates the situation.

This rule works up to the so-called “death zone”, or up to ~ 6500m, above which adaptation is impossible. And here it’s important to get down quickly.

“Internal” factors in the development of mountain sickness

There are a number of things that can and should be controlled to relieve symptoms:

Alcohol and caffeine They VERY greatly reduce resistance, mainly due to impaired exchange of water and salts. We strongly recommend that you avoid consuming these substances while climbing.

Violation of water-salt regime still occurs at high altitudes, because the body increases blood volume, and physical activity and changes in the cell membrane shift the balanceNa, KAndCa. aggravateuhThatIt’s not worth it - it accelerates the development of edema.

PIf you have kidney problems, the risk of developing pulmonary and cerebral edema increases.

Poor nutrition . The digestive system is one of the first to suffer from the miner; the absorption of water, proteins, vitamins and especially fats decreases. It is vital for a climber to replenish fluids, salts, vitamins, carbohydrates and proteins. Therefore, the diet should be varied, healthy and light.Eliminate complex fats - they still won’t be digested.Get energy from simple and complex carbohydrates, on the 2-3rd day be sure to introduce proteins into the diet, add a little salt to the water. Drink vitamins and dietary supplements with calcium and potassium.

>> Absolutely irreplaceable hot sweet hour with lemon. Vitamin C increases the body's resistance to altitude.

>> Read more about food distribution and metabolism in the article: Nutrition in the mountains.

Obesity often accompanied by changes in metabolism, liver problems, etc. People with overweight it is more difficult to deal with the effects of height.

P problems with blood flow rotation . Even minor bleeding can have a detrimental effect on the climber, leading to hypothermia, hypoxia, and edema.

ABOUTwill specifically note chronic problems with blood depot organs: liver and spleen. It was from here on the first dayHigh-altitude hypoxia releases red blood cells, which provides the “first level” of protection and adaptation. If you have problems with these organs, you need to think twice before climbing.

Pulmonary and cerebral edema

Ironically, it is the body's adaptation mechanisms to high altitudes that can lead to serious health problems. Promotion blood pressure and the total blood volume does not last indefinitely - there is a limit called compensatory barrier. Staying at altitude after the limit is reached leads to swelling of tissues - primarily the brain and lungs. When the compensation limit is reached, the permeability of blood vessels and cell membranes increases, and increased blood pressure enhances this effect: blood plasma enters the tissues, and the blood thickens. This causes swelling. The most dangerous are cerebral edema and pulmonary edema.

Pulmonary edema

or High altitude pulmonary edema (HAPE)- V Nonvascular fluid begins to accumulate in the alveoli of the lungs, and lung volume decreases. As a result, hypoxia increases. Signs:

• Attacks of severe, painful suffocation.
• Severe shortness of breath even without physical activity.
• A sharp increase in breathing (shallow, bubbling, audible at a distance).
• Rapid heartbeat due to lack of oxygen.
• First, coughing, and then a cough with severe wheezing and the release of foamy, pink sputum; etc.

In the absence of medical attention, it can lead to death. Death comes due to asphyxia due to excessive foaming.

Brain swelling

orHigh altitude cerebral edema ( HACE) . There is a for the same reasons. The released fluid begins to put pressure on the cerebral cortex from the inside, pressing it into the skull, which leads to disruption of the nerve centers and can be fatal.

Death comes due to compression of the cerebellum into the spinal cord trunk or due to compression of the cortex by the cranial vault.

Breathing at altitude

Also, at high altitudes, climbers wake up at night because they can’t breathe.

To saturate the body with oxygen, breathing quickens, causing carbon dioxide levels to drop. But CO 2 plays an important role in the regulation of breathing - it stimulates the respiratory center in the brain. While the climber is awake, inhalation/exhalation is regulated by consciousness, and during sleep - only by the respiratory center. Therefore, at night there is a phenomenon called Cheyne-Stokes breathing: breathing stops for a few seconds (the brain’s reaction to a lack of CO 2), and then is replaced by a series of rapid deep breaths and shallow exhalations (response to falling O 2 levels).

In fact, the climber regularly wakes up from severe suffocation, which passes within a minute or two after consciousness regains control of breathing and the person calms down.

Breathing problems are a normal reaction to lack of oxygen.

Prevention of altitude sickness

What should you do to minimize the symptoms of altitude sickness in high altitude conditions? There is a minimum set of three rules:

1. Never continue climbing mountains if you have symptoms of altitude sickness.
2. Be sure to go downstairs if the symptoms get worse
3. If you feel unwell for no reason, consider it mountain sickness.

Proper acclimatization

Primary weapon against high altitudes — correct acclimatization . You cannot force events, the body must have time to adapt.

At altitudes above 3500 m, you should not gain altitude too quickly. It is advisable to climb about 500 m per day, get plenty of rest and give the body time to adjust. Every 2 days after the crossing it is better to stop for a day. Enjoy the surrounding views and practice alpine training.

If you are not going on a solo hike, you should consider individual characteristics other participants.

It is advisable not to move on greater height behind a short time(helicopter, plane). However, this is not always possible. For example, you have to immediately fly to an altitude of 3000 m while trekking in Peru. If you get to a height in this way, you should spend 1-2 days at it without going higher.

It is very good to adhere to the rule of climbers - "walk high - sleep low". It is advisable to gain some altitude during the day, spend some time there, while receiving physical activity. For the night, go down a little lower (300 meters). We get a gear pattern of movement in the mountains.

Medicines for mountain sickness

Pharmacological drugs to relieve/relieve symptoms of mountain sickness:

1. Diakarb(acetazolamide or diamox) - diuretic, preventing swelling. Has many side effects, cannot be used as prophylactic. Acetazolamide can cause seizures because it leaches potassium from the body. Should be taken together with drugs containing potassium and magnesium, for example: panangin or asparkam.
2. Dexamethasone- relieves symptoms of altitude sickness, but does not promote acclimatization in any way. It has many side effects and is recommended for use only by those who cannot tolerate acetazolamide. You can take it a few hours before climbing.
3. Any vasodilator(to reduce pressure) with the lowest side effects(but not a dietary supplement).

For prevention Ginkgo biloba extract (vasodilator), antioxidants (tocopherol, ascorbic and lipoic acid), riboxin for cardiac support, coca leaves (available in the Andes) or preparations containing the extract.

Remember that at high altitudes you should always listen to yourself and if you feel very unwell, immediately go down.

Atmospheric pressure is the force of pressure of an air column per unit area. It is calculated in kilograms per 1 cm 2 of surface, but since previously it was measured only with mercury manometers, it is conventionally accepted to express this value in millimeters of mercury (mmHg). Normal atmospheric pressure is 760 mmHg. Art., or 1.033 kg/cm 2, which is considered to be one atmosphere (1 ata).

When performing certain types of work, it is sometimes necessary to work at high or low atmospheric pressure, and these deviations from the norm are sometimes within significant limits (from 0.15-0.2 ata to 5-6 ata or more).

The effect of low atmospheric pressure on the body

As you rise to altitude, atmospheric pressure decreases: the higher you are above sea level, the lower the atmospheric pressure. So, at an altitude of 1000 m above sea level it is equal to 734 mm Hg. Art., 2000 m - 569 mm, 3000 m -526 mm, and at an altitude of 15000 m - 90 mm Hg. Art.

With reduced atmospheric pressure, there is increased and deepening of breathing, increased heart rate (their strength is weaker), a slight drop in blood pressure, and changes in the blood are also observed in the form of an increase in the number of red blood cells.

The adverse effect of low atmospheric pressure on the body is based on oxygen starvation. It is due to the fact that with a decrease in atmospheric pressure, the partial pressure of oxygen also decreases, therefore, with the normal functioning of the respiratory and circulatory organs, less oxygen enters the body. As a result, the blood is not sufficiently saturated with oxygen and does not fully deliver it to organs and tissues, which leads to oxygen starvation (anoxemia). Such changes occur more severely when rapid decline atmospheric pressure, which happens during rapid takeoffs to high altitudes, when working on high-speed lifting mechanisms (cable cars, etc.). Fast growing oxygen starvation affects brain cells, which causes dizziness, nausea, sometimes vomiting, loss of coordination, memory loss, drowsiness; reduction of oxidative processes in muscle cells due to lack of oxygen is expressed in muscle weakness, rapid fatigue.

Practice shows that climbing to an altitude of more than 4500 m, where the atmospheric pressure is below 430 mm Hg, without oxygen supply for breathing is difficult to endure, and at an altitude of 8000 m (pressure 277 mm Hg) a person loses consciousness.

Blood, like any other liquid, upon contact with a gaseous medium (in this case in the alveoli of the lungs) dissolves a certain part of the gases - the higher their partial pressure, the greater the saturation of the blood with these gases. When atmospheric pressure decreases, partial pressure changes components air and, in particular, its main components - nitrogen (78%) and oxygen (21%); As a result, these gases begin to be released from the blood until the partial pressure equalizes. During a rapid decrease in atmospheric pressure, the release of gases, especially nitrogen, from the blood is so great that they do not have time to be removed through the respiratory system and accumulate in the blood vessels in the form of small bubbles. These gas bubbles can stretch tissue (even to the point of small tears), causing sharp pain, and in some cases form gas clots in small vessels, impeding blood circulation.

The complex of physiological and pathological changes, arising as a result of a decrease in atmospheric pressure, is called altitude sickness, since these changes are usually associated with an increase in altitude.

Preventing altitude sickness

One of the widespread and effective measures to combat altitude sickness is the supply of oxygen for breathing when ascending to high altitudes (over 4500 m). Almost all modern aircraft flying on high altitude, and especially spaceships, are equipped with sealed cabins, where, regardless of the altitude and atmospheric pressure outside, the pressure is maintained constant at a level that fully ensures the normal condition of the flight crew and passengers. This is one of the radical solutions to this issue.

When performing physical and intense mental work in conditions of low atmospheric pressure, it is necessary to take into account the relatively rapid onset of fatigue, therefore periodic breaks should be provided, and in some cases, a shortened working day.

To work in conditions of low atmospheric pressure, the physically strongest persons, absolutely healthy, mainly men aged 20 - 30 years, should be selected. When selecting flight personnel it is required mandatory check for so-called high-altitude qualification tests in special chambers with reduced pressure.

Training and hardening play an important role in the prevention of altitude sickness. It is necessary to play sports, systematically perform one or another physical work. The diet of those working at low atmospheric pressure should be high-calorie, varied and rich in vitamins and mineral salts.

Helpful information:

The Earth's air envelope, which is a mixture of various gases, exerts pressure on the earth's surface and all objects located on it. At sea level, every 1 cm 2 of any surface experiences a pressure of the vertical column of the atmosphere equal to 1.033 kg. Normal pressure is considered to be 760 mm Hg. Art. at sea level at 0°. The value of atmospheric pressure is also determined in bars. One normal atmosphere is equal to 1.01325 bar. One millibar is equal to 0.7501 mm Hg. Art. A weight of approximately 15-18 tons presses on the surface of the human body, but a person does not feel it, since the pressure inside the body is balanced by atmospheric pressure. Normal daily and annual fluctuations in air pressure are 20-30 mmHg. Art., do not have a noticeable effect on the well-being of healthy people.

However, in elderly people, as well as in patients with rheumatism, neuralgia, hypertension, before a sharp deterioration in weather, it is often observed bad feeling, general malaise, exacerbation of chronic diseases. These painful phenomena appear to occur as a result of the decrease in atmospheric pressure and other changes in meteorological factors that accompany bad weather.

As you rise in altitude, atmospheric pressure decreases; the partial pressure of oxygen in the air contained in the alveoli also decreases (i.e., that part of the total air pressure in the alveoli that is due to oxygen). These data are illustrated in Table 6.

From Table 6 it can be seen that as atmospheric pressure decreases with height, the value of the partial pressure of oxygen in the alveolar air also decreases, which at an altitude of about 15 km is practically equal to zero. But already at an altitude of 3000-4000 m above sea level, a decrease in the partial pressure of oxygen leads to an insufficient supply of oxygen to the body (acute hypoxia) and the occurrence of a number of functional disorders. Headaches, shortness of breath, drowsiness, tinnitus, a feeling of pulsation of the vessels of the temporal region, impaired coordination of movements, pallor of the skin and mucous membranes, etc. appear. Disorders of the central nervous system are expressed in a significant predominance of excitation processes over inhibition processes; there is a deterioration in the sense of smell, a decrease in auditory and tactile sensitivity, and a decrease in visual functions. This entire symptom complex is usually called altitude sickness, and if it occurs when climbing mountains, mountain sickness (Table 6).

There are five height tolerance zones:
1) safe, or indifferent (up to a height of 1.5-2 km);
2) full compensation zone (from 2 to 4 km), where some functional shifts are quickly eliminated in the body due to the mobilization of the body’s reserve forces;
3) zone of incomplete compensation (4-5 km);
4) a critical zone (from 6 to 8 km), where the above violations intensify, and death may occur in the least trained people;
5) a lethal zone (above 8 km), where a person can exist for no more than 3 minutes.

If the pressure change occurs quickly, then functional disorders in the ear cavities (pain, tingling, etc.), which can result in rupture of the eardrum. To eliminate oxygen? fasting uses special equipment that adds oxygen to the inhaled air and protects the body from possible disorders caused by hypoxia. At altitudes above 12 km, only a pressurized cabin or a special spacesuit can provide sufficient partial pressure of oxygen.

It is known, however, that people living in mountain villages at high altitudes, employees of high-mountain stations, as well as trained climbers who rise to an altitude of 7000 m above sea level and more, and pilots who have undergone special training, experience an addiction to others atmospheric conditions; their impact is balanced by compensatory functional changes reactivity of the body, which primarily includes adaptation of the central nervous system. Phenomena from the hematopoietic, cardiovascular and respiratory systems also play a significant role (an increase in the number of red blood cells and hemoglobin, which are oxygen carriers, an increase in the frequency and depth of breathing, and blood flow speed).

Increased pressure does not occur under normal conditions; it is observed mainly when performing production processes at great depths under water (diving and so-called caisson work). For every 10.3 m of immersion, the pressure increases by one atmosphere. While working at high blood pressure There is a decrease in pulse rate and pulmonary ventilation, decreased hearing, pale skin, dry mucous membranes of the nasal and oral cavities, indentation of the abdomen, etc.

All these phenomena are significantly weakened and ultimately disappear completely with a slow transition to normal atmospheric pressure. However, if this transition is carried out quickly, then severe pathological condition, called decompression sickness. Its origin is explained by the fact that when staying in conditions high pressure(starting from about 90 m) a large amount of dissolved gases (mainly nitrogen) accumulate in the blood and other body fluids, which, when quickly leaving the high pressure zone to normal, are released in the form of bubbles and clog the lumen of small blood vessels. As a result of the resulting gas embolism, a number of disorders are observed in the form of itching of the skin, damage to joints, bones, muscles, changes in the heart, pulmonary edema, various types of paralysis, etc. In rare cases, death is observed. To prevent decompression sickness, it is necessary, first of all, to organize the work of caisson workers and divers in such a way that the exit to the surface is carried out slowly and gradually to remove excess gases from the blood without the formation of bubbles. In addition, the time spent by divers and caisson workers on the ground must be strictly regulated.

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

Low mountains - up to 1000 m. Here a person does not experience (compared to areas located at sea level) the negative effects 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. What is characteristic of these altitudes is that even under conditions of rest, a complex of changes caused by oxygen deficiency is detected in the body of a healthy person.

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

The 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, thanks to the mobilization of all adaptive reactions, the body successfully copes with oxygen deficiency and the manifestation of other negative factors influence of altitude. Therefore, it is still possible to locate long-term posts, stations, etc. here, that is, live and work permanently.

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

c) Adaptation zone - up to 7000 m. The body's adaptation to altitude here is short-lived and temporary. Already with a relatively short (about two to three weeks) stay at such altitudes, the adaptation reactions become exhausted. In this regard, clear signs of hypoxia appear in the body.

d) Partial adaptation zone - 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 activity is partially disrupted. Thus, the reduced performance of systems and organs responsible for replenishing energy costs does not ensure restoration of strength, and human activity largely occurs at the expense of 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 effects of heights, a person can stay at these heights using internal reserves only for an extremely limited time, about 2 - 3 days.

The given values ​​of the altitudinal boundaries of the zones have, of course, average values. Individual tolerance, as well as a number of factors outlined below, can change the indicated values ​​for each climber by 500 - 1000 m.

The body's adaptation to altitude depends on age, gender, physical and mental state, degree of training, degree and duration of oxygen starvation, intensity of muscle effort, and the presence of high-altitude experience. The individual resistance of the body to oxygen starvation also plays an important role. Previous illnesses, poor nutrition, insufficient rest, lack of acclimatization significantly reduce the body's resistance to mountain sickness - a special condition of the body that occurs when inhaling rarefied air. Great importance has a rapid climb rate. 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 altitudes of 5800 - 6000 m signs of mountain sickness, expressed in varying degrees, appear in almost all people.

The development of altitude 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, and the degree of electrification of the atmosphere. Since these factors depend, in turn, on the latitude of the area, distance from water spaces and similar reasons, then the same altitude in different mountainous regions of the country has a different effect on the same person. For example, in the Caucasus, signs of mountain sickness may appear already at altitudes of 3000-3500 m, in Altai, Fan Mountains and Pamir-Alai - 3700 - 4000 m, Tien Shan - 3800-4200 m and Pamir - 4500-5000 m.

Signs and nature of the effects of mountain sickness

Mountain sickness can manifest itself suddenly, especially in cases where a person has significantly exceeded the limits of his individual tolerance in a short period of time, or has experienced excessive overexertion in conditions of oxygen starvation. However, most often, mountain sickness develops gradually. Its first signs are general fatigue, regardless of the amount of work performed, apathy, muscle weakness, drowsiness, malaise, and dizziness. If a person continues to remain at altitude, 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 healing process is quite slow.

In the early stages 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, moving into the second stage - chronic. Its symptoms are the same, but much more pronounced. strong degree: the headache can be extremely acute, drowsiness is more pronounced, the vessels of the hands are overflowing with blood, nosebleeds are possible, shortness of breath is pronounced, the chest becomes wide, barrel-shaped, observed increased irritability, loss of consciousness is possible. These signs indicate serious illness and the need to urgently transport the patient down. Sometimes the listed manifestations of the disease are preceded by a stage of excitement (euphoria), very reminiscent of alcohol intoxication.

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

At high altitudes, hypoxia has a more serious effect on the functional state of higher nerve centers, causing dulling of sensitivity, impaired judgment, loss of self-criticism, interest and initiative, and sometimes memory loss. The speed and accuracy of the reaction noticeably decreases; as a result of the weakening of internal inhibition processes, movement coordination is disrupted. Mental and physical depression, expressed in slowness of thinking and action, a noticeable loss of intuition and the ability to think logically, and changes 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 he was seriously affected by hypoxia, despite the sometimes dangerous consequences of his actions.

The sick person may develop obsession, a feeling of the absolute correctness of one’s actions, intolerance to critical remarks, and this, if the group leader, a person responsible for the lives of other people, finds himself in such a state, becomes especially dangerous. It has been noticed that under the influence of hypoxia, people often make no attempts to get out of an obviously dangerous situation.

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

Disproportionately great effort when completing a task;

A more critical attitude towards other travel participants;

Reluctance to do mental work;

Increased irritability of the senses;

Touchiness;

Irritability when receiving comments about work;

Difficulty concentrating;

Slowness of thinking;

Frequent, obsessive return to the same topic;

Difficulty remembering.

As a result of hypoxia, thermoregulation may also be disrupted, which is why in some cases At low temperatures, the body's heat production decreases, and at the same time, heat loss through the skin increases. Under these conditions, a person suffering from altitude sickness is more susceptible to chilling than other participants in the trip. In other cases, chills and an increase in body temperature by 1-1.5 ° C may occur.

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

Respiratory system.

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

Performance.

It is well known that any muscular activity, and especially intense activity, 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 an ascent to a high altitude, 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 discrepancy, oxygen starvation develops, and under-oxidized metabolic products accumulate in the body in excess quantities. Therefore, a person’s performance decreases sharply with increasing altitude. 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 performed at sea level.

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

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

Table 1

However, the capabilities of pulmonary ventilation have their own limit, which the body reaches before the maximum performance 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 increased pulmonary ventilation, and consequently to increased “washing out” of CO 2 from the body. But a decrease in the partial pressure of CO 2 reduces activity activity respiratory center and thereby limits the volume of pulmonary ventilation.

At altitude, pulmonary ventilation reaches maximum values ​​even when performing an average load for normal conditions. That's why maximum amount There is less intensive work in a certain time that a tourist can perform in high altitude conditions, and the 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 acclimatization of the body, the level of performance increases.

Digestive system.

At altitude, appetite changes significantly, absorption of water and nutrients decreases, and excretion gastric juice, 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, the person suddenly loses weight. Thus, during one of the expeditions to Everest, climbers who lived at an altitude of more than 6000 m within 6-7 weeks, lost weight from 13.6 to 22.7 kg. At altitude, a person may feel an imaginary feeling of fullness in the stomach, distension in the epigastric region, nausea, and diarrhea that cannot be treated with medication.

Vision.

At altitudes of about 4500 m normal visual acuity is possible only at a brightness 2.5 times higher than normal for plain conditions. At these altitudes, there is a narrowing of the peripheral field of vision and a noticeable “fogging” of vision as a whole. At high altitudes, the accuracy of gaze fixation and the correctness of determining distance also decreases. Even in mid-altitude conditions, vision weakens at night, and the period of adaptation to darkness lengthens.

Pain sensitivity

as hypoxia increases, it decreases until it is completely lost.

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 at one o'clock. With average physical activity in normal climatic conditions at sea level, water consumption increases to 40-50 grams per day for every kilogram of a person’s weight. In total, on average, under normal conditions, about 3 are released per day. l water. With increased muscle activity, especially in hot conditions, the release of water through the skin increases sharply (sometimes up to 4-5 liters). But intense muscular work performed in high altitude conditions, due to a 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 among participants in difficult high-altitude trips can reach 7-10 l per day.

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

Pneumonia begins after physical fatigue and hypothermia. IN initial stage there is poor health, some shortness of breath, rapid pulse, and cough. But after about 10 hours, the patient’s condition worsens sharply: the respiratory rate is over 50, the pulse is 120 per minute. Despite taking sulfonamides, pulmonary edema develops within 18-20 hours, which poses a great danger in high altitude conditions. The first signs of acute pulmonary edema: dry cough, complaints of compression slightly below the sternum, shortness of breath, weakness during physical activity. In serious cases, hemoptysis, suffocation, severe disturbance of consciousness occur, followed by death. The course of the disease often does not exceed one day.

The formation of pulmonary edema at altitude is usually based on 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 within a short time. Hemoglobin in 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, a person quickly dies from insufficient (below the permissible norm) oxygen supply to the body’s tissues.

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

Mechanism of development of mountain sickness

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

According to the law of diffusion, gases move from a medium with a higher partial pressure to a medium with a lower pressure. Gas exchange, both in the lungs and in the human blood, occurs due to the existing difference in these pressures.

At normal atmospheric pressure 760 mmp t. Art. The 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 the blood, but it is bound by the hemoglobin protein found in red blood globules- red blood cells. 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 tissue capillaries, blood hemoglobin 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), amounts to

0 10 20 30 40 50 60 70 80 90 100

Oxygen partial pressure mm.pm.cm.

Rice. 2.

at the moment of flow venous blood to the lungs at the end of the circulatory cycle only 40 mmHg Art. Thus, between venous and arterial blood there is a significant pressure difference 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.), pressure drop is 7-10 mmHg Art.

As a result of the existing pressure difference, oxygen passes from the pulmonary alveoli into the blood, and directly in the tissues of the body, this oxygen from the blood diffuses 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 increasing altitude, the partial pressures of gases decrease. So, at an altitude of 5550 m(which corresponds to atmospheric pressure 380 mmHg Art.) for oxygen it is equal to:

380x0.2094=80 mmHg Art.,

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

Naturally, a number of protective compensatory and adaptive reactions occur in the human body. So, first of all, lack of oxygen leads to excitation of chemoreceptors - nerve cells, very sensitive to a decrease in oxygen partial pressure. Their excitement serves as a signal for deepening and then increased breathing. The expansion of the lungs that occurs in this case 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 breathing, ventilation of the lungs increases, during which increased removal (“washing out”) of carbon dioxide from the body occurs. This phenomenon is especially intensified with 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 per minute the body loses about 0.3-0.35 l CO 2 at rest and up to 2.5 l during intense muscular work. As a result, a lack of CO 2 occurs in the body - the so-called hypocapnia, characterized by a decrease in the partial pressure of carbon dioxide in the arterial blood. But carbon dioxide plays an important role in regulating the processes of respiration, blood circulation and oxidation. A serious lack of CO 2 can lead to paralysis of the respiratory center, to sharp fall blood pressure, deterioration of heart function, impaired nervous activity. Thus, a decrease in blood pressure CO 2 by an amount from 45 to 26 mm. r t.st. 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 CO 2 content in the body disrupts the acid-base balance towards an excess of alkalis. Trying to restore this balance, the kidneys spend several days intensively removing this excess of alkalis from the body along with urine. This achieves acid-base balance at a new, lower level, which is one of the main signs of the end of the adaptation period (partial acclimatization). But at the same time, the amount of the body’s alkaline reserve is disrupted (decreased). When suffering from mountain sickness, a decrease in this reserve contributes to its further development. This is explained by the fact that it is enough sharp decrease the amount of alkalis reduces the blood’s ability to bind acids (including lactic acid) formed during hard work. This in a short time changes the acid-base ratio towards an excess of acids, which disrupts the functioning 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. In this case, 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 fairly large role here.

Acclimatization

During a long stay at altitude, a number of changes occur in the body, the essence of which boils down to maintaining normal human functioning. This process is called acclimatization. Acclimatization is the sum of adaptive-compensatory reactions of the body, as a result of which good general condition is maintained, weight constancy, normal performance and the normal course of psychological processes are maintained. A distinction is made 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 final or long-term) adaptation of the body to new climatic conditions.

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

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

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

table 2

and then by increasing the respiratory rate:

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

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

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

Upon completion of the acclimatization process at altitudes up to 5500 m all these parameters are reduced to normal values ​​characteristic of 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, and work of the cardiovascular system never decrease to normal value, because here some human organs and systems 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 fewer 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 body to adapt to new climatic conditions.

To eliminate the possibility of serious mountain sickness, as well as to shorten the acclimatization time, we can recommend the following set of measures, carried out both before leaving for the mountains and during the trip.

Before a long high-mountain trip, including passes above 5000 in the route of your route m, all candidates must be subjected to a special medical and physiological examination. Persons who cannot tolerate oxygen deficiency, who are physically insufficiently prepared, or who have suffered from pneumonia, sore throat or serious flu during the pre-trip preparation period should not be allowed to participate in such hikes.

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

You should know that among tourists who are physically unprepared for high-altitude travel, the vital capacity of the lungs at the beginning of the hike even decreases somewhat, the maximum performance of the heart (compared to trained participants) also becomes 8-10% less, and the reaction of increasing hemoglobin and red blood cells with oxygen deficiency is delayed .

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

Active acclimatization for mountaineering and for high-mountain hiking trips has differences in the methods of its implementation. This difference is explained, first of all, by the 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 area of ​​the High Wall, Trans-Alay and some others ridges in the Pamirs). The difference lies in the fact that climbing to the peaks along technically difficult routes takes several days, and along complex traverses even weeks (without a significant loss of altitude at individual intermediate stages), while in high-mountain hiking trips, which have as a rule, they are longer, and less time is spent on overcoming the passes.

Lower altitudes, shorter stay at these W- honeycombs and faster descent from significant loss altitudes make the acclimatization process easier for tourists, and quite multiple alternating ascents and descents softens, or even stops, the development of mountain sickness.

Therefore, climbers during high-altitude ascents are forced to allocate up to two weeks at the beginning of the expedition for training (acclimatization) ascents to lower peaks, which differ from the main object of ascent to an altitude of about 1000 meters. For tourist groups whose routes pass through passes with an altitude of 3000-5000 m, no special acclimatization exits are required. For this purpose, as a rule, it is sufficient to choose a route such that during the first week - 10 days the height of the passes traversed by the group would gradually increase.

Since the greatest discomfort caused by the general fatigue of a tourist who has not yet become involved in the hiking life is usually felt in the first days of the hike, even when organizing a day trip at this time, it is recommended to conduct classes on movement techniques, on the construction of snow huts or caves, as well as exploration or training trips to height. Specified practical lessons and exits must be done at a good pace, which forces the body to react more quickly to thin air and to more actively adapt to changes in climatic conditions. N. Tenzing’s recommendations are interesting in this regard: at altitude, even in a bivouac, you need to be physically active - heat snow water, monitor the condition of tents, check equipment, move more, for example, after setting up tents, take part in the construction of a snow kitchen, help distribute ready-made food by tents.

Proper nutrition is also essential in the prevention of mountain sickness. At an altitude of over 5000 m diet daily nutrition must have at least 5000 large calories. The carbohydrate content in the diet should be increased by 5-10% compared to normal nutrition. In areas associated with intense muscle activity, you should first consume an easily digestible carbohydrate - glucose. Increased consumption of carbohydrates 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 to combat dehydration. In addition, an increase in the volume of fluid consumed promotes the removal of under-oxidized metabolic products from the body through the kidneys.

The human body performing long-term intensive work in high altitude conditions requires an increased (2-3 times) amount of vitamins, especially those that are part of enzymes involved in the regulation of redox processes and closely related to metabolism. These are B vitamins, where the most important are B 12 and B 15, as well as B 1, B 2 and B 6. Thus, vitamin B15, in addition to the above, helps to increase the body’s performance at altitude, significantly facilitating the performance of large and intense loads, increases the efficiency of oxygen use, activates oxygen metabolism in tissue cells, and increases altitude resistance. This vitamin enhances the mechanism of active adaptation to lack of oxygen, as well as the oxidation of fats at altitude.

In addition to them, vitamins C, PP and folic acid in combination with iron glycerophosphate and metacil also play an important role. This complex has an effect on increasing the number of red blood cells and hemoglobin, that is, increasing 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, Schisandra and yellow sugar). E. Gippenreiter recommends the following complex of drugs that increase the body’s adaptability to hypoxia and alleviate 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 sodium phosphate.

How long after returning to the plain does the body retain the changes that occurred in it during the process of acclimatization?

At the end of a trip in the mountains, depending on the altitude of the route, changes in the respiratory system, blood circulation and the composition of the blood itself acquired during the process of acclimatization pass quite quickly. Thus, the increased hemoglobin content 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 body’s acclimatization to altitude lasts only up to three months.

True, after repeated trips to the mountains, the body develops a kind of “memory” for adaptive reactions to height. Therefore, the next time he goes to the mountains, his organs and systems, already following “beaten paths,” quickly find the right path to adapt the body to the lack of oxygen.

Providing assistance with mountain sickness

If, despite the measures taken, any of the participants in the high-altitude trek exhibit symptoms of altitude sickness, it is necessary:

For headaches, take citramon, pyramidon (no more than 1.5 g per day), analgin (no more than 1 G on one-time appointment and 3 g per day) or combinations thereof (troika, quintuple);

For nausea and vomiting - aeron, sour fruits or their juices;

For insomnia - Noxiron, when a person has difficulty falling asleep, or Nembutal, when sleep is not deep enough.

When using medications at high altitudes, special care should be taken. First of all, this applies to biological active substances(phenamine, phenatine, 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 during the descent, when the duration of the upcoming movement is not long. An overdose of these drugs leads to depletion of the nervous system, to sharp decline performance. An overdose of these drugs is especially dangerous in conditions of prolonged oxygen deficiency.

If the group has decided to urgently descend a sick participant, then during the descent it is necessary not only to systematically monitor the patient’s condition, but also to regularly give injections of antibiotics and drugs that stimulate human cardiac and respiratory activity (lobelia, cardamine, corazol or norepinephrine).

SUN EXPOSURE

Sunburn.

From prolonged exposure to the sun on the human body, sunburn forms on the skin, which can cause painful condition tourist

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

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 reflection of rays from surrounding objects).

The amount of solar energy flow falling on a particular area of ​​the earth's surface depends on the altitude 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 longest shortcut through the atmosphere. At a sun altitude of 30°, this path doubles, and at sunset - 35.4 times more than with a vertical incidence of the rays. Passing through the atmosphere, especially through its lower layers, which contain suspended particles of dust, smoke and water vapor, the sun's rays are absorbed and scattered to a certain extent. Therefore, the longer the path of these rays through the atmosphere, the more polluted it is, the lower the intensity of solar radiation they have.

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

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

The total intensity of the direct solar radiation flux, even at the same altitude of the sun, changes its value depending on the season. Thus, in summer, due to rising temperatures, increasing humidity and dust reduce the transparency of the atmosphere so much that the flow value at a sun altitude of 30° is 20% less than in winter.

However, not all components of the spectrum sun rays change their intensity to the same extent. The intensity increases especially sharply 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 this period in the same weather conditions the time required for

redness of the skin, at an altitude 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). As the altitude of the sun decreases, 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 altitude 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 denser clouds of the middle and especially lower tiers can reduce it to zero .

IN total value Scattered radiation plays a significant role in incoming solar radiation. Scattered radiation illuminates places in the shade, and when the sun is obscured by dense clouds over an area, it creates general daylight illumination.

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

Scattered radiation in a clear sky without clouds, caused mainly by atmospheric gas molecules, is sharply different in its spectral composition both from other types of radiation and from scattered radiation in a cloudy sky. The maximum energy in its spectrum is shifted to the region of shorter waves. And although the intensity of scattered radiation under 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 bluer of which is more intense the cleaner the air.

In the lower layers of air, when solar rays are scattered from large suspended particles of dust, smoke and water vapor, the maximum intensity shifts to the region of longer waves, as a result of which the color of the sky becomes whitish. In a whitish sky or in the presence of light 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 magnitude is closely related to the number, shape and location of clouds. So, if at standing tall When the sky is covered by clouds by 50-60%, the intensity of scattered solar radiation reaches values ​​equal to the flux of direct solar radiation. With further increase in cloudiness and especially as it thickens, the intensity decreases. With cumulonimbus clouds it can be even lower than with a cloudless sky.

It should be taken into account that if the flux 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. Diurnal changes in illumination highest value scattered ultraviolet radiation occurs in the middle of the day, and in the annual - in winter.

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

The intensity of reflected solar radiation depends on physical properties surface and the angle of incidence of sunlight. Wet black soil reflects only 5% of the rays falling on it. This is because reflectivity decreases significantly with increasing soil moisture and roughness. But alpine meadows reflect 26%, polluted glaciers - 30%, clean glaciers and snow surfaces - 60-70%, and freshly fallen snow - 80-90% of the incident rays. Thus, when moving in the highlands on snow-covered glaciers, a person is exposed to a reflected flux that 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. Thus, 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-wave range (ultraviolet rays). You should know that the lighter the surface, the greater the amount of ultraviolet rays reflected from the earth's 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, scattered or reflected), but with their total impact. On the plains, 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 intensity of radiation in general 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 under direct solar radiation in plain conditions by 8-10 times!

By affecting exposed areas of the human body, ultraviolet rays penetrate human skin to a depth of only 0.05 to 0.5 mm, Causing, at moderate doses of radiation, redness and then darkening (tanning) of the skin. In the mountains, exposed 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, body burns can easily occur.

Externally, the first signs of burns associated with solar radiation do not correspond to the degree of damage. This degree is revealed somewhat later. Based on the nature of the injury, burns are generally divided into four degrees. For the considered sunburn, in which only the upper layers of the skin are affected, only the first two (mild) degrees are inherent.

I is the mildest degree of burn, characterized by redness 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, and sometimes peeling of the skin is observed.

Stage II is characterized by a more pronounced inflammatory reaction: intense redness of the skin and detachment of the epidermis with the formation of blisters filled with clear or slightly cloudy liquid. Complete restoration of all layers of skin occurs in 8-12 days.

First degree burns are treated by tanning the skin: the burned areas are moistened with alcohol and a solution of potassium permanganate. When treating second degree burns, primary treatment of the burn site is performed: wiping with gasoline or 0.5%. solution of ammonia, irrigating the burned area with antibiotic solutions. Considering the possibility of infection while traveling, it is better to cover the burn area with an aseptic bandage. Rarely changing the dressing promotes the rapid restoration of affected cells, since this does not damage the layer of delicate young skin.

During a mountain or ski trip, the neck, earlobes, face and skin suffer the most from exposure to direct sunlight. outside hands As a result of exposure to scattered, and when moving through the snow and reflected rays, the chin, lower part of the nose, lips, and skin under the knees are subject to burns. Thus, almost any open area of ​​the human body is susceptible to burns. On warm spring days when driving in the highlands, especially in the first period, when the body does not yet have a tan, under no circumstances should you be allowed to remain in the sun for a long time (more than 30 minutes) without a shirt. The delicate skin of the abdomen, lower back and sides of the chest is most sensitive to ultraviolet rays. We must 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. Subsequently, with repeated repeated exposure to ultraviolet irradiation, the skin becomes tanned and becomes less sensitive to these rays.

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

Rice. 7

But due to the fact that the face and hands are the most exposed areas of the body, they suffer most from sunburn. Therefore, sunny days, the face should be protected with a gauze bandage. To prevent the gauze from getting into your mouth when 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 bent in an arc (rice. 7).

In the absence of a mask, the parts of the face most susceptible to burns can be covered with a protective cream such as “Ray” or “Nivea”, and the lips with colorless lipstick. To protect the neck, it is recommended to sew double-folded gauze to the headdress from the back of the head. You should especially take care of your shoulders and hands. If with a burn

shoulders, the injured participant cannot carry a backpack and all of its additional weight falls on other comrades, then if the hands are burned, the victim will not be able to provide reliable insurance. Therefore, on sunny days, wearing a long-sleeved shirt is mandatory. Back sides Hands (when moving without gloves) must be covered with a layer of protective cream.

Snow blindness

(eye burn) occurs during a relatively short (within 1-2 hours) movement in the snow on a sunny day without protective glasses as a result of the 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 a lit match (photophobia). Some swelling of the mucous membrane is observed, and later blindness may occur, which, if measures are taken in a timely manner, disappears without a trace in 4-7 days.

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

The use of safety glasses made of organic glass during 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, have the greatest impact. physiological effects, still reaches the eyes. Prolonged exposure to such, even reduced amounts of ultraviolet rays, can eventually lead to eye burns.

It is also not recommended to take canned glasses on a hike that fit tightly to your face. Not only the glass, but also the skin of the area of ​​the face covered by it fogs up heavily, causing an unpleasant sensation. Much better is the use of ordinary glasses with sides made of wide adhesive plaster (Fig. 8).

Rice. 8.

Participants of long hikes in the mountains must have spare glasses at the rate of one pair for three people. If you don’t have spare glasses, you can temporarily use a gauze blindfold or put cardboard tape over your eyes, making narrow slits in it first in order to see only a limited area of ​​​​the terrain.

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

Sunstroke

A severe painful condition that occurs suddenly during long treks as a result of many hours of exposure infrared rays direct sunlight on an uncovered head. At the same time, during a hike, the back of the head is exposed to the greatest impact of rays. The resulting outflow of arterial blood and a sharp stagnation of venous blood in the veins of the brain lead to swelling and loss of consciousness.

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

A headdress that protects the head from exposure to sunlight and, in addition, maintains 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.

First, let's remember the physics course high school, which explains why and how atmospheric pressure changes with altitude. The higher the area is above sea level, the lower the pressure there. It is very simple to explain: atmospheric pressure indicates the force with which a column of air presses on everything that is on the surface of the Earth. Naturally, the higher you rise, the lower the height of the air column, its mass and the pressure exerted will be.

In addition, at altitude the air is rarefied, it contains a much smaller number of gas molecules, which also immediately affects the mass. And we must not forget that with increasing altitude, the air is cleared of toxic impurities, exhaust gases and other “delights”, as a result of which its density decreases and atmospheric pressure drops.

Studies have shown that the dependence of atmospheric pressure on altitude differs as follows: an increase of ten meters causes a decrease in the parameter by one unit. As long as the altitude of the area does not exceed five hundred meters above sea level, changes in the pressure of the air column are practically not felt, but if you rise five kilometers, the values ​​​​will be half the optimal ones. The strength of the pressure exerted by the air also depends on the temperature, which decreases greatly when rising to a higher altitude.

For the level of blood pressure and the general condition of the human body, the value of not only atmospheric pressure, but also partial pressure, which depends on the concentration of oxygen in the air, is very important. In proportion to the decrease in air pressure, the partial pressure of oxygen also decreases, which leads to an insufficient supply of this necessary element cells and tissues of the body and the development of hypoxia. This is explained by the fact that the diffusion of oxygen into the blood and its subsequent transportation to the internal organs occurs due to the difference in the partial pressure of the blood and the pulmonary alveoli, and when rising to a high altitude, the difference in these readings becomes significantly smaller.

How does altitude affect a person's well-being?

Main negative factor The main effect on the human body at altitude is the lack of oxygen. It is as a result of hypoxia that acute disorders of the heart and blood vessels, increased blood pressure, digestive disorders and a number of other pathologies develop.

Hypertensive patients and people prone to pressure surges should not climb high into the mountains and it is advisable not to take long flights. ABOUT professional pursuits They will also have to forget about mountaineering and mountain tourism.

The severity of the changes occurring in the body made it possible to distinguish several altitude zones:

• Up to one and a half to two kilometers above sea level is a relatively safe zone in which no special changes are observed in the functioning of the body and the state of vital systems. Deterioration in well-being, decreased activity and endurance are observed very rarely.
• From two to four kilometers - the body tries to cope with the oxygen deficiency on its own, thanks to increased breathing and taking deep breaths. Heavy physical work, which requires the consumption of large amounts of oxygen, is difficult to perform, but light exercise is well tolerated for several hours.
• From four to five and a half kilometers - the state of health noticeably worsens, performing physical work is difficult. Psycho-emotional disorders appear in the form of high spirits, euphoria, and inappropriate actions. When staying at such a height for a long time, headaches, a feeling of heaviness in the head, problems with concentration, and lethargy occur.
• From five and a half to eight kilometers - exercise physical work impossible, the condition worsens sharply, the percentage of loss of consciousness is high.
• Above eight kilometers - at this altitude a person is able to maintain consciousness for a maximum of several minutes, after which deep fainting and death follows.

For metabolic processes to occur in the body, oxygen is necessary, the deficiency of which at altitude leads to the development of altitude sickness. The main symptoms of the disorder are:

• Headache.
• Increased breathing, shortness of breath, lack of air.
• Nose bleed.
• Nausea, attacks of vomiting.
• Joint and muscle pain.
• Sleep disorders.
• Psycho-emotional disorders.

At high altitudes, the body begins to experience a lack of oxygen, as a result of which the functioning of the heart and blood vessels is disrupted, arterial and intracranial pressure, vital signs fail internal organs. To successfully overcome hypoxia, you need to include nuts, bananas, chocolate, cereals, and fruit juices in your diet.

Effect of altitude on blood pressure levels

When rising to a high altitude, thin air causes an increase in heart rate and an increase in blood pressure. However, with a further increase in altitude, blood pressure levels begin to decrease. A decrease in the oxygen content in the air to critical values ​​causes depression of cardiac activity, a noticeable decrease in pressure in the arteries, while in venous vessels indicators are increasing. As a result, a person develops arrhythmia and cyanosis.

Not long ago, a group of Italian researchers decided for the first time to study in detail how altitude affects blood pressure levels. To conduct research, an expedition to Everest was organized, during which the participants’ pressure levels were determined every twenty minutes. During the hike, an increase in blood pressure during ascent was confirmed: the results showed that the systolic value increased by fifteen, and the diastolic value by ten units. It was noted that the maximum blood pressure values ​​were determined at night. The effect has also been studied antihypertensive drugs at different heights. It turned out that the drug under study effectively helped at an altitude of up to three and a half kilometers, and when rising above five and a half it became absolutely useless.