How does altitude affect pressure levels? Treatment of pulmonary edema. About mountain air and acclimatization

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 mmHg. Art. To the surface human body presses a weight of approximately 15-18 tons, 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 sharp deterioration weather 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 from 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, a decrease 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 - thanks to mobilization reserve forces body;
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 may result in rupture 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 on high altitude, employees of high-altitude 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, become accustomed to the surrounding atmospheric conditions; their impact is balanced by compensatory functional changes reactivity of the body, which primarily includes adaptation of the central nervous system. A significant role is also played by phenomena from the hematopoietic, cardiovascular and respiratory systems(increased number of red blood cells and hemoglobin, which are oxygen carriers, increased frequency and depth of breathing, blood flow speed).

High blood 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 heart rate and pulmonary ventilation, decreased hearing, pale skin, dry mucous membranes of the nasal and oral cavities, abdominal depression, 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 approximately 90 m) accumulates in the blood and other body fluids a large number of dissolved gases (mainly nitrogen), 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 the joints, bones, muscles, changes in the heart, pulmonary edema, various types paralysis, etc. In rare cases, it is observed fatal outcome. 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.

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 health, 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;
• heart rate increases and blood pressure increases, blood flow 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.

Upon occurrence mountain sickness It’s not just the altitude that affects it, but also 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 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 physical training of a person are manifested 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 altitude sickness to alcohol intoxication, only very strong and lasting. Based on this, many can imagine what awaits in 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. How more blood enters 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 precisely the mechanisms of adaptation of the body to high altitudes that can lead to serious problems with health. 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 limit of compensation is reached, the permeability of blood vessels and cell membranes increases, and increased arterial 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 production of foamy sputum, Pink colour; etc.

With absence medical care may be fatal. 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 pressing of the cerebellum into the trunk spinal cord 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 the level carbon dioxide falls. 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 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 - normal reaction due 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". During the day, it is advisable to gain some altitude, spend some time there, while getting 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 contribute to 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.

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 blood pressure levels and general condition human body The value of not only atmospheric, 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 conditions of the heart and blood vessels, increased blood pressure, digestive disorders and a number of other pathologies.

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 there are no special changes in the functioning of the body and the state of vitality. important 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 that requires the consumption of large amounts of oxygen is difficult to perform, but light load well tolerated for several hours.
• From four to five and a half kilometers - the state of health noticeably worsens, performing physical work is difficult. Appear psychoemotional disorders 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 flow in the body metabolic processes Oxygen is needed, 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.