Hypoxia: consequences, causes, signs, symptoms, treatment

One of the mandatory conditions for the life of the body is continuous education and energy consumption. It is spent to ensure metabolism, to preserve and renew the structural elements of organs and tissues, as well as to carry out their functions. Lack of energy in the body leads to significant metabolic disorders, morphological changes and dysfunctions, and often to the death of the organ and even the organism. The basis of energy deficiency is hypoxia.

Hypoxia is a typical pathological process, usually characterized by a decrease in oxygen content in cells and tissues. It develops as a result of insufficiency of biological oxidation and is the basis for disturbances in the energy supply of functions and synthetic processes of the body.

Types of hypoxia

Depending on the causes and characteristics of the development mechanisms, the following types are distinguished:

1. Exogenous:
   hypobaric;
2. normobaric.
3. Respiratory (breathing).
4. Circulatory (cardiovascular).
5. Hemic (blood).
6. Tissue (primary tissue).
7. Overload (stress hypoxia).
8. Substrate.
9. Mixed.

Depending on the prevalence in the body, hypoxia can be general or local (with ischemia, stasis or venous hyperemia of individual organs and tissues).

Depending on the severity of the course, mild, moderate, severe and critical hypoxia is distinguished, which is fraught with death of the body.

Depending on the speed of occurrence and duration of the course, hypoxia can be:

• lightning - occurs within a few tens of seconds and often ends in death;
• acute - occurs within a few minutes and can last several days:
• chronic - occurs slowly, lasts several weeks, months, years.

General characteristics of hypoxia

Definition of hypoxia

Hypoxia is a typical and dangerous pathological process that occurs in the body during a wide range of diseases and acute conditions, and provokes them. For example, hypoxia can be caused by various factors, and also accompany a wide range of diseases, and may even be the main link in the appearance of pathological changes or diseases.

Based on this:

hypoxia is a typical general pathological process and does not relate to either a diagnosis or a syndrome.

The effect of hypoxia at the cellular level is divided into two types - adaptive reactions and decompensation .

During the occurrence of hypoxia, the body launches adaptive protective reactions that maintain for a short time the almost normal functioning of organs and tissues. With prolonged exposure to hypoxia, the body's reserves run out and adaptive defense reactions are switched off - decompensation occurs.

Decompensation is characterized by the occurrence of irreversible disorders in organs and tissues - from organ failure to death.

Development of hypoxia

Compensatory reactions during hypoxia are expressed by oxygen deficiency at the cellular level, and their task is to restore the amount of oxygen in tissues. The complex of compensatory reactions to eliminate the influence of hypoxia includes the organs of the cardiovascular and respiratory systems, and changes in biochemical processes in tissues and organ structures that suffer most from oxygen deficiency are triggered. Until the supply of compensatory reactions is completely exhausted, organs and tissues will not suffer from a lack of oxygen. However, if, when compensatory mechanisms are depleted, the supply of oxygen is not normalized, then irreversible decompensation will begin in the tissues with damage to cells and dysfunction of the entire organ.

In acute and chronic hypoxia, the nature of compensatory reactions is different. Thus, during acute hypoxia, compensatory reactions consist of increased breathing and blood circulation, that is, blood pressure rises, tachycardia occurs (heart rate more than 70 beats per minute), breathing becomes deep and frequent, the heart pumps a larger volume of blood per minute than normal . In addition, in response to acute hypoxia, all “reserves” of red blood cells, which are necessary to carry oxygen to the cells, are released into the systemic circulation from the bone marrow and spleen.

hypoxia

All these reactions are aimed at normalizing the amount of oxygen delivered to the cells by increasing the volume of blood passing through the vessels per unit of time and increasing the amount of oxygen transferred. With very severe acute hypoxia, in addition to the development of these reactions, centralization of blood circulation also occurs, which consists of redirecting all available blood to vital organs (heart and brain) and a sharp decrease in blood supply to the muscles and organs of the abdominal cavity. The body directs all the oxygen to the brain and heart - organs critical for survival, and, as it were, “deprives” those structures that are currently not needed for survival (liver, stomach, muscles, etc.).

If acute hypoxia is eliminated without depleting the body's reserves, then the person will survive, and all his organs and systems will function completely normally after some time. If hypoxia continues longer than the period of effectiveness of compensatory reactions, then irreversible changes will occur in organs and tissues.

Compensatory reactions during chronic hypoxia develop against the background of severe long-term diseases or conditions. First, to compensate for oxygen deficiency, the number of red blood cells in the blood increases, which allows the volume of oxygen carried by the same volume of blood per unit time to increase. Also, in red blood cells, the activity of an enzyme increases, facilitating the transfer of oxygen from hemoglobin directly to the cells of organs and tissues. New alveoli are formed in the lungs, breathing deepens, the volume of the chest increases, additional vessels are formed in the lung tissue, which improves the supply of oxygen to the blood from the surrounding atmosphere. The heart, which has to pump more blood per minute, hypertrophies and increases in size. Changes also occur in tissues - the number of mitochondria (organelles that use oxygen to ensure cellular respiration) increases in cells, and many new capillaries are formed in tissues. It is precisely because of the activation of microcirculation and a large number of capillaries during hypoxia that a person develops a pinkish coloration of the skin, which is mistaken for a “healthy” blush.

Adaptive reactions during acute hypoxia are reflexive, and therefore, when oxygen starvation is eliminated, they cease their effect, and the organs completely return to the mode of functioning in which they existed before the development of the episode of hypoxia. In chronic hypoxia, adaptive reactions are not reflexive; they develop due to the restructuring of the functioning mode of organs and systems, and therefore their action cannot be quickly stopped after oxygen starvation is eliminated.

With chronic hypoxia, the body can change its functioning mode in such a way that it completely adapts to conditions of oxygen deficiency and does not suffer from it at all. For example, this is how the body of residents of megacities adapts.

In acute hypoxia, complete adaptation to oxygen deficiency cannot occur, since the body simply does not have time to rearrange its functioning modes, and all its compensatory reactions are designed only to temporarily maintain the functioning of organs until adequate oxygen delivery is restored.

That is why a person can have a state of chronic hypoxia for many years without interfering with his normal life and work, while acute hypoxia in a short period of time can lead to death or irreversible damage to the brain or heart.

Compensatory reactions during hypoxia always lead to changes in the functioning of the most important organs and systems. These manifestations of compensatory reactions can be conditionally considered symptoms of hypoxia.

About the disease

The development of hypoxia is most often caused by unfavorable conditions associated with the professional activities of people or poor ecology. The condition is assessed as a typical pathological process in which tissues and organs are not sufficiently supplied with oxygen. These changes occur at the cellular level.

At first, the body tries to somehow adapt, systems and organs begin to function with oxygen deficiency. Over time, adaptive reactions weaken, which leads to depletion of the body's resources and the activation of the decompensation mechanism. Compensatory reactions are wasted gradually, and for some time the internal organs do not feel the lack of oxygen too acutely.

If adequate oxygen supply is not restored in a timely manner, all vital systems of the body may suffer. The respiratory process directly involves the respiratory organs and the cardiovascular system. The compensatory process leads to disruption of biochemical metabolism in tissues at the cellular level. The organs that suffer the most are those that undergo changes due to oxygen starvation.

An acute lack of oxygen leads to centralization of blood circulation, in which the main flow of blood begins to be directed to the brain, heart and lungs, and not to muscle tissue and other internal organs. Systems that do not play a primary role in the survival process are deprived. Insufficient blood supply is fraught with the development of destructive processes in cells, which can be irreversible.

The disease in an advanced stage entails the development of other pathologies, such as myocardial infarction, myocarditis, diseases of the cardiovascular system and respiratory organs. The result of severe hypoxia is asphyxia, characterized by a complete lack of oxygen, which ultimately leads to suffocation and death.

One of the most common types of oxygen starvation is fetal hypoxia, the development of which is caused by congenital defects or intrauterine infection in the embryo caused by poor health in the mother.

Types of hypoxia

Hypoxia, depending on the mechanism of development, is divided into:

• Exogenous hypoxia (hypoxic hypoxia) is caused by environmental factors.
• Endogenous hypoxia is caused by various diseases or disorders that a person has:
• Respiratory (respiratory, pulmonary) hypoxia.
• Circulatory (cardiovascular) hypoxia: Ischemic; Stagnant.
• Hemic (blood) hypoxia: Anemic; Caused by inactivation of hemoglobin.
• Tissue (histotoxic) hypoxia. Substrate hypoxia.
• Overload hypoxia. Mixed hypoxia.

Depending on the speed of development and course:

• Lightning fast (instant) – develops within a few seconds (no longer than 2 – 3 minutes);
• Acute – develops within several tens of minutes or hours (no longer than 2 hours);
• Subacute – develops within several hours (no longer than 3-5 hours);
• Chronic – develops and lasts for weeks, months or years.

Depending on the prevalence of oxygen starvation , hypoxia is divided into general and local .

Exogenous hypoxia

Exogenous hypoxia (hypoxic) is caused by a decrease in the amount of oxygen in the inhaled air. Accordingly, blood leaves the lungs that is not sufficiently saturated with oxygen and a small amount of gas is brought to the cells of various organs/tissues. Exogenous hypoxia is manifested by cyanosis (blueness of the skin and mucous membranes), dizziness and fainting.

exogenous hypoxia normobaric

Depending on atmospheric pressure, exogenous hypoxia is divided into hypobaric and normobaric.

Hypobaric hypoxia is caused by low oxygen content in rarefied air with low atmospheric pressure. Such hypoxia develops in mountainous areas and at high altitudes.

Normobaric hypoxia develops when there is a low oxygen content in air with normal atmospheric pressure. Normobaric exogenous hypoxia can develop when being in mines, wells, on submarines, in diving suits, in cramped rooms with large crowds of people, with general air pollution or smog in cities, as well as during surgery if anesthesia-respiratory equipment malfunctions.

Respiratory (respiratory, pulmonary) hypoxia

respiratory hypoxia

Respiratory (respiratory, pulmonary) hypoxia develops in diseases of the respiratory system (bronchitis, pulmonary hypertension, any lung pathologies, etc.), when the penetration of oxygen from the air into the blood is difficult. Against the background of respiratory hypoxia, complications may develop, such as respiratory failure, cerebral edema and gas acidosis.

Circulatory (cardiovascular) hypoxia

circulatory hypoxia
Circulatory (cardiovascular) hypoxia develops against the background of various circulatory disorders (for example, decreased vascular tone, decreased total blood volume after blood loss or dehydration, increased blood viscosity, increased coagulability, centralization of blood circulation, venous stagnation, etc.). If a circulatory disorder affects the entire network of blood vessels, then systemic . If blood circulation is disrupted only in the area of ​​an organ or tissue, then hypoxia is local .

During circulatory hypoxia, a normal amount of oxygen enters the blood through the lungs, but due to circulatory disorders, it is delivered to organs and tissues with a delay, as a result of which oxygen starvation occurs in the latter.

According to the mechanism of development, circulatory hypoxia is ischemic and stagnant. The ischemic form of hypoxia develops with a decrease in the volume of blood passing through organs or tissues per unit of time. This form of hypoxia can occur with left ventricular heart failure, heart attack, cardiosclerosis, shock, collapse, vasoconstriction of some organs and other situations.

The stagnant form of hypoxia develops when the speed of blood movement through the veins decreases - with thrombophlebitis of the legs, right ventricular heart failure, increased intrathoracic pressure and other situations when blood stagnation occurs in the venous bed. In the stagnant form of hypoxia, venous blood does not return to the lungs in time to remove carbon dioxide and saturate with oxygen. As a result, there is a delay in the delivery of the next portion of oxygen to organs and tissues.

Hemic (blood) hypoxia

Hemic (blood) hypoxia develops when quality characteristics are impaired or the amount of hemoglobin in the blood decreases. Hemic hypoxia is divided into two forms - anemic and caused by changes in hemoglobin quality .

hemic hypoxia

Anemic hemic hypoxia is caused by a decrease in the amount of hemoglobin in the blood, that is, anemia of any origin or hydremia (dilution of the blood due to fluid retention in the body). During anemic hypoxia, oxygen is normally bound and transported by the blood to organs and tissues. But due to the fact that there is too little hemoglobin, insufficient oxygen is brought to the tissues and hypoxia occurs in them.

Hypoxia, caused by a change in the quality of hemoglobin, is associated with poisoning by various toxic substances, which lead to the formation of forms of hemoglobin that are not capable of carrying oxygen (methemoglobin or carboxyhemoglobin). When the quality of hemoglobin changes, its quantity remains normal, but it loses its ability to carry oxygen. As a result, when passing through the lungs, hemoglobin is not saturated with oxygen and the blood flow does not deliver it to the cells of all organs and tissues. A change in the quality of hemoglobin occurs when poisoned by a number of chemicals, such as carbon monoxide (carbon monoxide), sulfur, nitrites, nitrates, etc.

Tissue (histotoxic) hypoxia

Tissue (histotoxic) hypoxia develops against the background of impaired ability of organ cells to absorb oxygen. The cause of tissue hypoxia is reduced activity or deficiency of mitochondrial respiratory chain enzymes, which convert oxygen into forms in which it is used by cells to carry out all life processes.

Disruption of respiratory chain enzymes can occur in the following cases:

• Suppression of the activity of respiratory chain enzymes in case of poisoning with cyanide, ether, urethane, barbiturates and alcohol;
• Lack of enzymes of the respiratory chain due to deficiency of vitamins B1, B2, PP and B5;
• Disruption of the enzymes of the respiratory chain due to poisoning with nitrates, microbial toxins, exposure to large amounts of thyroid hormones, etc.;
• Damage to the structure of enzymes due to exposure to radioactive radiation, uremia, cachexia, severe infectious diseases, etc.

Tissue hypoxia can exist for a long period of time.

Substrate hypoxia

substrate hypoxia

Substrate hypoxia develops with normal oxygen delivery to tissues, but in conditions of a lack of basic nutrients that undergo oxygen oxidation. Substrate hypoxia can develop during fasting, diabetes and other conditions when there is not enough glucose and fatty acids in the cells.

Overload hypoxia

overload hypoxia

Overload hypoxia can develop during heavy physical work, when cells intensively consume oxygen. In such cases, the cells simply do not have enough oxygen delivered. Such physiological hypoxia is not dangerous and goes away after completing the stage of high physical activity.

Mixed hypoxia

Mixed hypoxia is a combination of several types of endogenous hypoxia and occurs with severe, life-threatening lesions of various organs and systems, such as shock, poisoning, coma, etc.

Acute hypoxia

Acute hypoxia develops quickly, within several tens of minutes, and persists for a limited period of time, ending either with the elimination of oxygen starvation, or with irreversible changes in organs that will lead to severe illness or even death. Acute hypoxia usually accompanies acute conditions in which blood flow, quantity and quality of hemoglobin sharply change, such as, for example, blood loss, cyanide poisoning, heart attack, etc.

acute hypoxia

Any variant of acute hypoxia must be eliminated as soon as possible, since the body will be able to maintain the normal functioning of organs and tissues for a limited period of time until compensatory and adaptive reactions are exhausted. And when the compensatory-adaptive reactions are completely exhausted, the most important organs and tissues (primarily the brain and heart) will begin to die under the influence of hypoxia.

In principle, acute hypoxia is more dangerous than chronic hypoxia, since it can quickly lead to disability, organ failure or death. And chronic hypoxia can exist for years, giving the body the opportunity to adapt and live and function quite normally.

Chronic hypoxia

chronic hypoxia

Chronic hypoxia develops over several days, weeks, months or even years, and occurs with long-term diseases. The body adapts to chronic hypoxia by changing the structure of cells to new conditions, which allows organs to function quite normally. In principle, chronic hypoxia is safer than acute hypoxia, because develops slowly and the body is able to adapt to new conditions using compensation mechanisms.

The essence of the phenomenon and its forms

The pathological condition is classified according to the type of course. Accordingly, they talk about two varieties.

Acute

Acute myocardial hypoxia develops rapidly, in a matter of minutes. Leads to generalized cardiac dysfunction.

There are a lot of nonspecific symptoms: from shortness of breath to severe chest pain. Recovery is urgent, but often the ambulance doesn’t even have time to get there. Death occurs in 80-90% of cases within an hour from the onset of an acute attack.

The reasons are not so much the lethality of the process itself, but the need for urgent competent assistance, which few can provide.

If the patient is successfully saved, a sluggish type of pathological process develops. They require long-term treatment. The effect is unpredictable and depends on the individual characteristics of the patient and his medical history.

Chronic

Chronic hypoxia occurs most often. It accounts for up to 70% of all clinically recorded situations.

Relatively mild symptoms are noted in the early stages, then a period of serious deterioration begins, with increasing restrictions, first in physical activity, then in work activity, and finally the person reaches the point where no mechanical work is possible.

Not only is it impossible to work, but even taking care of yourself at home or getting out of bed becomes akin to a feat.

Treatment is effective only in the early stages. If the root cause cannot be eliminated, there is a chance to stop the manifestations, but not to cure the process completely. Symptomatic therapy allows you to slow down anatomical changes in the myocardium, but not radically eradicate them.

Regardless of the form, the lack of oxygen in the heart has a single essence: there is a metabolic disorder in the cardiac structures, and the function of cardiomyocytes decreases.

The result is a reflex narrowing (stenosis) of the coronary arteries, which are precisely responsible for adequate myocardial trophism. As a result of insufficient nutrition of muscles and active cells, the contractility of the organ decreases.

The result is heart failure, which leads to the death of cardiomyocytes, scarring of the affected areas and even greater dysfunction.

This is a cyclical process. If the vicious circle is not broken, the patient’s death is a matter of time, often insignificant.

Myocardial hypoxia

myocardial hypoxia

Myocardial hypoxia is one of the most dangerous diseases and is characterized by insufficient oxygen supply to the heart muscle.

This condition occurs when there is a sudden decrease in oxygen supply to the heart muscle. Cells do not have time to adapt to changed conditions. Metabolism continues in them, but it becomes incomplete, and under-oxidized metabolites accumulate. If hypoxia persists, cardiac muscle tissue dies.

Clinically, this condition is manifested by attacks of chest pain, increasing their duration and intensity. Subsequently, myocardial infarction develops - necrosis of the heart muscle with loss of its contractile function.

Myocardial hypoxia can be caused by the following reasons:

• low oxygen content in atmospheric air;
• diseases of the lungs with impaired gas exchange in them;
• decrease in the amount of blood flowing through the myocardium due to pathology of the coronary arteries;
• deterioration of the blood's ability to carry oxygen, for example, with carbon monoxide poisoning;
• disruption of oxygen utilization by the cells themselves, for example, in case of poisoning with cyanides and heavy metals.

Diagnostics

To determine the severity of the patient’s condition, the following methods are used:

• pulsometry - measuring the pulse rate at the wrist or carotid artery using a stopwatch;
• pulse oximetry - determining the degree of oxygen saturation in the blood based on the level of hemoglobin using a spectrophotometric device.

The pulse rate of a healthy person should be between 50-60 beats/min. Blood oxygen saturation should not be less than 95%.

In laboratory conditions, cardiac hypoxia is diagnosed using the following methods:

• electrocardiography (ECG);
• ultrasound examination (ultrasound) of the heart;
• X-ray of the lungs;
• biochemical blood test.

The most complete assessment of the condition of the heart muscle is made possible by cardiac ultrasound. It is used to determine the cardiac ejection fraction and areas of damaged muscle fibers with reduced functionality.

Important information: What is polycythemia vera and polycythaemic syndrome

Consequences of hypoxia

The consequences of hypoxia can be different and depend on the period of time during which oxygen starvation was eliminated and how long it lasted. If hypoxia was eliminated during a period when the compensatory mechanisms were not exhausted, then there will be no negative consequences; after some time, the organs and tissues will completely return to their normal mode of operation. But if hypoxia was eliminated during the period of decompensation, when compensatory mechanisms were exhausted, then the consequences depend on the duration of oxygen starvation. The longer the period of hypoxia against the background of decompensation of adaptive mechanisms, the stronger and deeper the damage to various organs and systems. Moreover, the longer hypoxia lasts, the more organs are damaged.

During hypoxia, the brain suffers the most, since it can withstand without oxygen for 3-4 minutes, and from the 5th minute necrosis will begin to form in the tissues. The heart muscle, kidneys and liver are able to tolerate a period of complete absence of oxygen for 30-40 minutes.

The consequences of hypoxia are always due to the fact that in cells, in the absence of oxygen, the process of oxygen-free oxidation of fats and glucose begins, which leads to the formation of lactic acid and other toxic metabolic products that accumulate and ultimately damage the cell membrane, leading to its death. When hypoxia lasts long enough from the toxic products of improper metabolism, a large number of cells in various organs die, forming entire areas of dead tissue. Such areas sharply worsen the functioning of the organ, which is manifested by corresponding symptoms, and in the future, even with the restoration of oxygen flow, will lead to a persistent deterioration in the functioning of the affected tissues.

The main consequences of hypoxia are always caused by disruption of the central nervous system, since it is the brain that suffers primarily from oxygen deficiency. Therefore, the consequences of hypoxia are often expressed in the development of a neuropsychiatric syndrome, including parkinsonism, psychosis and dementia. In 50-70% of cases, neuropsychiatric syndrome can be cured. In addition, a consequence of hypoxia is exercise intolerance, when with minimal exertion a person experiences palpitations, shortness of breath, weakness, headache, dizziness and pain in the heart area. Also, the consequences of hypoxia can be hemorrhages in various organs and fatty degeneration of muscle, myocardial and liver cells, which will lead to disruptions in their functioning with clinical symptoms of failure of one or another organ, which can no longer be eliminated in the future.

Forecast

The prognosis is determined by the duration and intensity of the cause, as well as the reactivity of the body. Longer periods of oxygen deprivation, especially in infants, young children and the elderly, tend to cause more damage. There is no single treatment that can cure or reverse brain damage. Doctors also don't fully understand brain damage, so it's impossible to make reliable predictions. Some people recover completely. Others never recover.

Hypoxia - causes

The causes of exogenous hypoxia may be the following factors:

• Thin atmosphere at altitude (mountain sickness, altitude sickness, pilot sickness);
• Being in tight spaces with large crowds of people;
• Being in mines, wells or in any enclosed spaces (for example, submarines, etc.) with no communication with the outside environment;
• Poor ventilation of premises;
• Working in diving suits or breathing through a gas mask;
• Severe air pollution or smog in the city of residence;
• Malfunction of anesthesia-respiratory equipment.

The causes of various types of endogenous hypoxia may be the following factors:

• Respiratory diseases (pneumonia, pneumothorax, hydrothorax, hemothorax, destruction of alveolar surfactant, pulmonary edema, pulmonary embolism, tracheitis, bronchitis, emphysema, sarcoidosis, asbestosis, bronchospasm, etc.);
• Foreign bodies in the bronchi (for example, accidental swallowing of various objects by children, choking, etc.);
• Asphyxia of any origin (for example, due to compression of the neck, etc.);
• Congenital and acquired heart defects (non-closure of the foramen ovale or the duct of Batal, rheumatism, etc.);
• Damage to the respiratory center of the central nervous system due to injuries, tumors and other diseases of the brain, as well as when it is suppressed by toxic substances;
• Impaired breathing mechanics due to fractures and displacements of the chest bones, damage to the diaphragm or muscle spasms;
• Cardiac dysfunction caused by various heart diseases and pathologies (heart attack, cardiosclerosis, heart failure, electrolyte imbalance, cardiac tamponade, pericardial obliteration, blockade of electrical impulses in the heart, etc.);
• A sharp narrowing of blood vessels in various organs;
• Arteriovenous shunting (transfer of arterial blood into veins through vascular shunts before it reaches organs and tissues and releases oxygen to cells);
• Stagnation of blood in the inferior or superior vena cava system;
• Thrombosis;
• Poisoning with chemicals that cause the formation of inactive hemoglobin (for example, cyanide, carbon monoxide, lewisite, etc.);
• Anemia;
• Acute blood loss;
• Disseminated intravascular coagulation syndrome (DIC syndrome);
• Impaired metabolism of carbohydrates and fats (for example, diabetes, obesity, etc.);
• Shock and coma;
• Excessive physical activity;
• Malignant tumors of any location;
• Chronic kidney and blood diseases (for example, leukemia, anemia, etc.);
• Deficiency of vitamins PP, B1, B2 and B5;
• Thyroid diseases;
• Damage to cells by radiation, tissue breakdown products due to cachexia, severe infections or uremia;
• Drug and alcohol abuse;
• Prolonged fasting.

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Symptoms (signs) of hypoxia

symptoms of hypoxia

In the fulminant form of hypoxia, clinical symptoms do not have time to appear, since death occurs within a very short period of time (up to 2 minutes).

The acute form of hypoxia lasts up to 2-3 hours, and during this period there is a failure of all organs and systems at once, primarily the central nervous system, respiration and heart (heart rate becomes less frequent, blood pressure drops, breathing becomes irregular, etc.). If hypoxia is not eliminated during this period, then organ failure progresses to coma and agony, followed by death.

Subacute and chronic forms of hypoxia are manifested by the so-called hypoxic syndrome. Against the background of hypoxic syndrome, symptoms from the central nervous system first appear, since the brain is most sensitive to oxygen deficiency, as a result of which foci of necrosis (dead areas), hemorrhages and other types of cell destruction quickly appear in its tissues. Due to necrosis, hemorrhage and death of brain cells against the background of oxygen deficiency at the initial stage of hypoxia, a person develops euphoria, he is in an excited state, and he is tormented by motor restlessness. One's own condition is not assessed critically.

With further progression of hypoxia, the following signs of depression of the cerebral cortex appear, which are similar in manifestations to alcohol intoxication:

• Drowsiness;
• Lethargy;
• Headache and dizziness;
• Noise in ears;
• Lethargy;
• Impaired consciousness;
• Involuntary passage of urine and feces;
• Nausea and vomiting;
• Movement coordination disorder;
• Cramps.

Convulsions during hypoxia appear when exposed to external stimuli. Moreover, a convulsive attack usually begins with twitching of the muscles of the face, hands and feet with the addition of random muscle contractions of the abdomen. Sometimes during convulsions opisthotonus , which represents a person arched with straightened neck and back muscles, head thrown back and arms bent at the elbows. The posture of a person in opisthotonus resembles the gymnastic figure “bridge”.

In addition to symptoms of depression of the cerebral cortex, a person also experiences pain in the heart area, irregular breathing, shortness of breath, a sharp decrease in vascular tone, tachycardia (an increase in heart rate of more than 70 beats per minute), a drop in blood pressure, cyanosis (blueness of the skin), decrease in body temperature. But when poisoned with substances that inactivate hemoglobin (for example, cyanides, nitrites, nitrates, carbon monoxide, etc.), human skin becomes pinkish in color.

With prolonged hypoxia with the slow development of damage to the central nervous system, a person may develop mental disorders in the form of delirium (“delirium tremens”), Korsakov’s syndrome (loss of orientation, amnesia, replacement of real events by fictitious events, etc.) and dementia.

With further progression of hypoxia, blood pressure drops to 20-40 mmHg. Art. and a coma occurs with loss of brain function. If blood pressure drops below 20 mmHg. Art., then death occurs. In the period before death, a person may experience agonizing breathing in the form of rare convulsive attempts to breathe.

Degrees of hypoxia

Depending on the severity and severity of oxygen deficiency, the following degrees of hypoxia are distinguished:

• Mild (usually detected only during physical activity);
• Moderate (phenomena of hypoxic syndrome appear at rest);
• Severe (the symptoms of hypoxic syndrome are strongly expressed and there is a tendency to transition to a coma);
• Critical (hypoxic syndrome has led to coma or shock, which can result in agony and death).

Treatment of oxygen starvation

In practice, mixed forms of hypoxia usually develop , as a result of which the treatment of oxygen deficiency in all cases should be comprehensive, aimed simultaneously at eliminating the causative factor and maintaining an adequate supply of oxygen to the cells of various organs and tissues.

To maintain a normal level of oxygen supply to cells in any type of hypoxia, hyperbaric oxygenation (HBO) - barotherapy - is used. In barotherapy, pressure chambers are used in which a person is under increased pressure with a high oxygen content. Due to the increased pressure, oxygen is additionally dissolved directly in the blood plasma, without contacting red blood cells, which allows its delivery to organs and tissues in the required quantity, regardless of the activity and functional usefulness of hemoglobin. Thanks to hyperbaric oxygenation, it is possible not only to supply organs with oxygen, but also to dilate the blood vessels of the brain and heart, so that the latter can work at full capacity.

In addition to hyperbaric oxygenation, cardiac drugs and drugs that increase blood pressure are used for circulatory hypoxia. If necessary, a blood transfusion is performed (if blood loss incompatible with life has occurred).

For hemic hypoxia, in addition to hyperbaric oxygenation, the following therapeutic measures are carried out:

• Blood or red blood cell transfusion;
• Introduction of oxygen carriers (Perftoran, etc.);
• Hemosorption and plasmapheresis to remove toxic metabolic products from the blood;
• Introduction of substances capable of performing the functions of enzymes of the respiratory chain (vitamin C, methylene blue, etc.);
• Introduction of glucose as the main substance that provides cells with energy to carry out vital processes;
• Administration of steroid hormones to eliminate severe oxygen starvation of tissues.

Medicines

When choosing an oxygen concentrator for use at home, attention is certainly paid to its cost, reliability and comfort. Currently, the leading position is occupied by oxygen concentrators made in Germany. These devices have a long service life, high reliability, and low noise levels. In addition, the devices manufactured in Germany have a high-quality filtration system. The only disadvantage is the high cost, since not every person who needs an oxygen concentrator can afford this device. Oxygen concentrators made in the USA are almost in no way inferior. In addition, these devices are the lightest in the class of stationary oxygen concentrators, since the weight of some models does not exceed 14 kg. More budget options include devices developed in China, the price of which is significantly lower than others. Thanks to the advent of portable oxygen devices, it is possible to abandon stationary oxygen concentrates, since portable devices can be used as an autonomous source of oxygen supply at home, even if there are any problems with electricity.

Prevention of hypoxia

Effective prevention of hypoxia is to avoid conditions in which the body may experience oxygen starvation. To do this, you need to lead an active lifestyle, be in the fresh air every day, exercise, eat well, and promptly treat existing chronic diseases. When working in an office, you need to periodically ventilate the room (at least 2-3 times during the working day) to saturate the air with oxygen and remove carbon dioxide from it.

prevention of hypoxia in a pressure chamber

It is also recommended to undergo a course of barotherapy (oxygen capsules and pressure chambers) several times a year, which helps reduce cases of oxygen starvation in the body.