Death by bleeding. How much blood does it take to lose consciousness?

Blood loss called a process whose development occurs as a result bleeding. It is characterized by a set of adaptive and pathological reactions of the body to a decrease in blood volume in the body, as well as a lack of oxygen (), which was caused by a decrease in the transport of this substance in the blood.

The development of acute blood loss is possible in cases where there is damage to a large vessel, which causes a fairly rapid drop in blood pressure, which can drop to almost zero. This condition can also occur with a complete rupture of the aorta, pulmonary trunk, inferior or superior vein. Even despite insignificant blood loss, a sharp, almost instantaneous drop in pressure occurs, and anoxia(lack of oxygen) myocardium and brain. And this, in turn, leads to death. The general picture of blood loss consists of signs of acute death, damage to a large vessel, a small amount of blood in various body cavities and some other signs. For acute blood loss, there is no characteristic bleeding of the internal organs of the body, but with massive blood loss, a gradual leakage of blood from the vessels can be observed. The body loses half of its available blood. In a matter of minutes, the pressure drops, the skin becomes “marbled”, islanded, pale, limited spots appear, appearing later than with other types of death.

The main element in blood loss is the reduction circulating blood volume. The first reaction to this condition is spasm small arterioles and arteries, which occurs in the form reflex in response to irritation of certain areas of blood vessels and increased tone of the autonomic nervous system. Thanks to this, during blood loss, if its course develops slowly, it is possible to further maintain normal blood pressure. Vascular resistance increases in proportion to the severity of blood loss. As a result of a decrease in circulating blood volume, minute volume of blood circulation and venous flow to the heart decrease. To compensate, the force of the heart's contractions increases and the amount of blood in its ventricles decreases. The transferred blood loss leads to a change in the functional state of the heart muscle, ECG changes appear, conductivity is disrupted, arteriovenous shunts open, while part of the blood passes through the capillaries and immediately passes into the venules, the supply of blood to the muscles, kidneys and skin deteriorates.

The body tries on its own compensate lack of blood due to blood loss. This is achieved due to the fact that the interstitial fluid, as well as the proteins contained in it, penetrate into bloodstream, as a result of which the original volume can be restored. In cases where the body cannot cope with compensation of the volume of circulating blood, as well as when blood pressure is low for a long time, acute blood loss becomes irreversible condition which can last for hours. This condition is called hemorrhagic shock. In the most severe cases, it can develop thrombohemorrhagic syndrome, which is caused by a combination of increased levels of procoagulants in the blood and slow blood flow. The irreversible condition differs in many ways from acute blood loss and is similar to the terminal stage of traumatic shock.

Symptoms of blood loss

The volume of lost blood is not always associated with the clinical picture of blood loss. With a slow flow of blood, a blurred clinical picture is possible, or may be absent. The severity of blood loss is determined primarily based on the clinical picture. If blood loss occurs quickly and in large quantities, compensatory mechanisms may not have time to turn on, or may not be fast enough. Hemodynamics at the same time, oxygen transport deteriorates and decreases, due to which its accumulation and consumption by tissues decreases, the contractile function of the myocardium is disrupted due to oxygen starvation of the central nervous system, the minute volume of blood circulation decreases, due to which oxygen transport deteriorates even more. If this circle is not broken, the victim will face inevitable death. Some factors can increase the body's sensitivity to blood loss: concomitant diseases, ionizing radiation, shock, trauma, overheating or hypothermia, and some other circumstances. Women are more resilient and tolerate blood loss more easily, while older people, infants and newborns are extremely sensitive to blood loss.

There are blood losses hidden And massive. The former are characterized by a deficiency of and. With massive blood loss, volume deficiency leads to dysfunction of the cardiovascular system; even having lost only a tenth of the total blood volume with massive blood loss, the patient has a great threat to life. Absolutely fatal blood loss is one third of the total blood volume circulating in the body.

Based on the volume of blood lost, blood loss can be divided into:

Minor blood loss– less than 0.5 liters of blood. Minor blood loss, as a rule, is tolerated without any clinical symptoms or consequences. Pulse and blood pressure remain normal, the patient feels only slight fatigue, has a clear consciousness, and the skin has a normal shade.

For average blood loss typical blood loss is 0.5-1 liter. With it, pronounced tachycardia, blood pressure drops to 90-100 mm. Hg Art., breathing remains normal, nausea, dry mouth, dizziness develop, fainting is possible, severe weakness, twitching of individual muscles, a sharp loss of strength, and a slow reaction.

With large blood loss blood shortage reaches 1-2 liters. Blood pressure drops to 90-100 mm. Hg Art., a pronounced increase in breathing develops, tachycardia, severe pallor of the skin and mucous membranes, cold sticky sweat is released, the patient’s consciousness is clouded, he is tormented by vomiting and nausea, painful, pathological drowsiness, weakened vision, darkening in the eyes, tremors of the hands.

With massive blood loss There is a shortage of blood in a volume of 2-3.5 liters, which is up to 70% of the total volume of circulating blood. Blood pressure drops sharply and reaches 60 mm, the pulse is threadlike up to 150 beats per minute, and may not be palpable in peripheral vessels at all. The patient shows indifference to the surrounding environment, his consciousness is confused or absent, there is deathly pallor of the skin, sometimes with a blue-gray tint, cold sweat is released, convulsions and sunken eyes may occur.

Fatal blood loss occurs when there is a shortage of more than 70% of the body's blood. It is characterized by: blood pressure may not be determined at all, the skin is cold, dry, the pulse disappears, convulsions, dilated pupils, and death occur.

The main goal when treatment hemorrhagic shock is to increase the volume of circulating blood, as well as improve microcirculation. In the first stages of treatment, transfusion of fluids, such as glucose solution and saline solution, is established, which allows for prevention empty heart syndrome.

Instant stoppage of blood loss is possible when the source is accessible without. But in most cases, patients must be prepared for surgery, and various plasma expanders.

Infusion therapy, which is aimed at restoring blood volume, is carried out under the control of venous and arterial pressure, hourly pressure, peripheral resistance and cardiac output. Replacement therapy uses canned blood products, plasma substitutes, and their combinations.

Bleeding resulting from injury or disease can pose a real threat not only to health, but also to human life if the blood loss is large enough.

Blood is the most important substance in the human body, one of the main functions of which is to transport oxygen and other essential substances to the heart and tissues. Therefore, the loss of a significant amount of blood can significantly disrupt the normal functioning of the body or even lead to death.
In total, the average adult's body contains about 5 liters of blood. At the same time, he can lose some of it with virtually no harm to himself: for example, the volume of blood taken from a donor at a time is 450 milliliters. This amount is considered completely safe for an adult. A more or less serious problem may be the loss of 20% of the total blood volume or more.

Doctors say that the degree of danger of blood loss to a person’s life in a particular case depends not only on its volume, but also on the nature of the bleeding. Thus, the most dangerous is rapid bleeding, in which a person loses a significant amount of blood within a short period of time, not exceeding several tens of minutes.

With the loss of about one liter of blood, or about 20% of the total blood volume circulating in the body, the heart ceases to receive a sufficient volume of blood for circulation, a person experiences interruptions in heart rhythm, and the level of blood pressure and pulse rate sharply decrease. However, if blood loss can be stopped at this stage, it usually does not pose a significant threat to human life, and with sufficient nutrition and rest, the body is able to independently restore the lost volume.

In case of loss of 20% to 30% of blood in a relatively short time, which is equivalent to a volume of 1-1.5 liters of blood for an adult, there is increased sweating and thirst, nausea, and possible vomiting. The person becomes short of breath, becomes apathetic, his hands tremble, and his vision becomes blurry. In this case, even when the bleeding stops, independent restoration of the lost volume is usually difficult, and the person needs a transfusion.

With a rapid loss of 2-3 liters of blood, that is, 30% or more of the total amount available in the body, the surface of a person’s skin becomes cold, the person himself becomes noticeably pale, and the face and limbs acquire a bluish tint. In most cases, such blood loss is accompanied by loss of consciousness, and often by falling into a coma. In this case, only an immediate blood transfusion can save a person’s life. A rapid loss of 50% or more of the total amount of blood available in the body is considered fatal.
If the blood loss is gradual, for example, with internal bleeding, the body has time to adapt to the situation and is able to withstand significantly larger volumes of blood loss. For example, medicine knows cases of survival with a loss of 60% of blood after timely intervention.

With acute blood loss, the volume of circulating blood decreases significantly, a decrease in hemoglobin levels is noted, and circulatory failure develops. With insufficient compensatory mechanisms and significant blood loss, the picture of acute anemia quickly develops. Acute anemia is accompanied by general weakness, dizziness, pallor of the skin and visible mucous membranes, flashing “spots” before the eyes, thirst, yawning, confusion, increased heart rate and breathing, and blood pressure drops.

A dangerous complication of bleeding is hemorrhagic shock. A decrease in blood pressure to 70 mmHg is critical, and if it cannot be raised within 1-2 hours, irreversible changes develop in organs and tissues. The human body, especially children and the elderly, reacts extremely to acute blood loss.

During internal bleeding, the escaping blood can compress vital organs (heart, brain) and disrupt their function, which creates a direct threat to the patient’s life.

Blood poured into tissues and organs is a good breeding ground for microorganisms.

When the veins of the neck, large veins of the abdomen, and pelvis are injured, an air embolism may occur. Air embolism is characterized by suction of air, accompanied by whistling air. The accumulation of large amounts of air in the right ventricle can cause cardiac arrest.

In the absence of assistance to the victim, bleeding can lead to exsanguination and death from cardiac arrest and paralysis of the respiratory center due to severe hypoxia (oxygen starvation).

Have you ever wondered what a person thinks about when he dies? What kind of pain does he experience and what does he think about? A person will probably be able to finally understand this only when he finds himself in such a situation, and in the meantime we will try to describe these circumstances in our own words. It is known that death occurs when oxygen ceases to flow into the brain, and the reasons for this can be mass, suffocation, drowning, etc. After the access of oxygen to the brain becomes blocked, the person loses consciousness within 10 seconds, and final death occurs after 2 minutes.

How does a person feel when having a heart attack?
In fact, this is a rather long process, although many are accustomed to thinking that this is not so. At first, a person may experience various kinds of discomfort and pain in the chest; this pain can be long-lasting, and it can also disappear and then reappear. Pain can also radiate to different parts of the body, from the back and arms to the jaw; during a heart attack, a person usually feels shortness of breath, nausea, and also experiences cold sweat. Often people do not go to the hospital right away, but wait from 3 to 6 hours, as a result, sometimes there is not enough time to take the person to the hospital. As soon as the heart muscle stops, the person immediately loses consciousness and within two minutes he dies. If the person has managed to be taken to the hospital, they give him a direct cardiac massage, use a defibrillator, and also administer special drugs to get the heart beating again.

How do people feel when they drown?
Even if a person knows how to swim well, in cold water the chances of survival become much less. Therefore, where the water is always cold, people drown a few meters from the shore, while most of them know how to swim well. When the moment comes of understanding that a person is starting to drown, he begins to panic and flounder, while the person does not call for help, because... he tries with all his might to swallow air. This lasts for an average of 30 to 60 seconds and is then submerged under water, where the person may not inhale for 30 to 90 seconds, after which he inhales water, trying to cough up and consequently inhaling even more water. From an excess of water in the lungs, a person begins to experience a feeling of burning and tearing in the chest, and the muscles of the larynx contract. A little later, a feeling of euphoria sets in due to lack of oxygen, eventually the heart stops and the brain dies.

Death by fire
Hot smoke and fire scorch eyebrows and hair and burn the throat and airways, making it impossible to breathe. Burns cause severe pain by stimulating the pain nerves in the skin. As the burn area increases, sensitivity decreases somewhat, but not completely. Third degree burns do not damage as much as second degree wounds because the superficial nerves are destroyed. Some victims with severe burns reported feeling no pain while they were still in danger or engaged in rescuing others. Once the adrenaline and shock gradually wear off, pain quickly sets in. Most people who die in fires actually die from poisonous carbon monoxide poisoning and lack of oxygen. Some people just don't wake up. The rate at which headaches and drowsiness and unconsciousness appear depends on the size of the fire and the concentration of carbon monoxide in the air.

How does a person feel when he falls from a great height?
The maximum falling speed is approximately 200 km per hour and is achieved when jumping at least 145 meters. More than half of people die a few seconds or minutes after landing, the rest are forced to suffer for some time. It all depends on the position of the person during landing. If a person falls on his feet, then his chances of survival are greater; if a person falls on his head, then the outcome is almost 100% fatal. Jumping into the water is also not safe. Jumping from a great height into water, a person runs the risk of losing consciousness, breaking legs or having a heart attack.

How does a person feel when he hangs himself?
In this case, the noose compresses the artery and trachea that leads to the human brain. The most important thing here is the correct location of the loop; if it is in a “successful” position, the person loses consciousness within 10 seconds. If the loop is poorly placed, then the hanged person may writhe in pain for 2 minutes, and in some cases for 15 minutes. That is why, back in 1868, people began to hang themselves with a “long rope” in England; in this case, a person’s neck would break when falling, and he would die faster.

How does a person feel when he dies from blood loss?
Naturally, everything depends on the type of wound; the more serious it is, the faster the person will die. In the event of aortic rupture, death occurs within a few seconds, because the aorta is the main vessel. If you cut a vein or other artery, death may take several hours. On average, a person has 5 liters of blood, when a person loses 1.5 of them, he will feel thirsty, weak, and short of breath. After losing two liters, the person will become dizzy, lose consciousness, and then die.

How does a person feel in the electric chair?
At a voltage of 220 volts, a person loses consciousness after about 10 seconds and the main cause of death is considered to be death from arrhythmia (disruption of the normal functioning of the heart). If the voltage is high, the person loses consciousness almost immediately. In the electric chair, a person loses consciousness immediately, and his death occurs quite quickly due to the passage of electricity through the heart and brain. It is believed that this death is painless and humane, but not everyone agrees with this. Some scientists believe that during the electric chair, a person most likely dies from heating the brain, since the skull bone greatly limits the passage of current through the brain, or death occurs from respiratory paralysis.

How does a person feel when he is given a lethal injection?
This method replaced the electric chair as it was more humane. This method consists of injecting 3 drugs at once, first a painkiller so that the person does not feel anything, then a substance that stops breathing, and finally a drug that almost instantly stops the heart. In this case, each of the drugs is administered in an excessive dose. However, there have been cases where people who were injected with these drugs experienced convulsions.

How does a person feel as a result of decompression?
If an astronaut goes into outer space without a spacesuit, the first thing he will feel is the expansion of air in his lungs. If he does not have time to exhale, the lungs will rupture. At the same time, oxygen begins to leave the body. Under internal pressure, the body will begin to expand, but the elasticity of the skin will not allow the body to rupture. Bubbles of water vapor will form in the blood, which will clog the vessels, and as a result, the blood will stop taking part in gas exchange. Survivors of decompression accidents are mostly pilots whose planes depressurized. They reported sharp chest pain and an inability to breathe. After about 15 seconds they lost consciousness.

Every person at a conscious age thinks about death. What awaits us after death? Does the other world exist? Are we purely biological beings, or does each of us still have a certain soul that, after death, goes to another world? One of the many questions that arises in the mind is the unknown. Does a person experience torment, pain, or, on the contrary, do all sensations become dull before leaving for another world?

The issues discussed have worried people since their inception and still do. Scientists continue to study this mysterious phenomenon, but only a few questions can be answered.

Feelings of dying people

The physical sensations of a dying person will depend primarily on what led him to death. He can experience both severe pain and pleasant sensations.

As for psychological perception, at the moment of dying, most people instinctively feel fear, panic and horror, and try to “resist” death.

According to biology, after the heart muscle stops contracting and the heart stops, the brain continues to function for about five minutes. It is believed that in these last minutes, a person’s mind reflects on his life, vivid memories emerge, and the person, as it were, “sums up” his existence.

Death classification

Biological scientists divide death into two categories:

• Natural;
• Unnatural.

Natural death occurs according to the laws of normal physiology and occurs due to the natural aging of the body or in the case of underdevelopment of the fetus in the womb.

Unnatural death can occur due to the following reasons:

• Due to various serious diseases (oncological, cardiovascular, etc.);
• Mechanical impact: electric shock;
• Chemical exposure: or ;
• Unspecified - a seemingly healthy person dies suddenly from a latent disease or a sudden, acute form of the disease.

From a legal point of view, death is divided into:

• Non-violent;
• Violent.

Nonviolent death occurs in old age, long-term illness, and in other similar cases. Violent deaths include murder and suicide.

Stages of death

To better understand what a person may experience during death, we can consider the stages of the process, identified from a medical point of view:

• Preagonal stage. At this moment, a malfunction occurs in the blood circulation and breathing systems, causing hypoxia to develop in the tissues. This period lasts from several hours to several days;
• Terminal pause. At this moment, the person stops breathing, the functioning of the myocardium malfunctions;
• Agonal stage. The body is trying to return to life. At this stage, a person periodically stops breathing, the heart works increasingly weaker, which causes malfunctions in the functioning of all organ systems;
• Clinical death. Breathing and blood circulation stop. This stage lasts about five minutes, and it is at this moment that the person can be brought back to life with the help of a person;
• Biological death - a person finally dies.

Important! Only people who have experienced clinical death are the only ones who can accurately report what sensations are possible in a dying person.

Morbidity in various deaths

Cause	Time to die	Pain
Prescription drug overdose	129 minutes	8,5
Fall from height	5 minutes	17,78
Drowning	18 minutes	79
Shot in the head with a pistol	3 minutes	13
Fire	1 hour	91

Is it painful to die from cancer?

Cancer is one of the most common causes of death. Unfortunately, a cure for malignant carcinoma has not yet been discovered, and cancer at stages 3 and 4 is an incurable disease. All that doctors can do in this situation is to reduce the patient’s pain with the help of special analgesics and slightly prolong the person’s life.

A person with a cancer tumor does not always experience pain when dying. In some situations, before the death of a cancer patient, he begins to sleep a lot and ultimately plunges into a comatose state, after which he dies without feeling any physical ailment, that is, directly in his sleep. In another situation, the stages of dying of a cancer patient are as follows:

• Before death, the patient may experience migraines, see hallucinations and lose memory, as a result of which he cannot recognize his loved ones;
• Speech disturbances occur, it is more difficult for the patient to say connected sentences, he may utter awkward phrases;
• The person may experience blindness and/or deafness;
• As a result, the motor functions of the body are impaired.

However, this is only a general average picture of how a person with cancer feels before death.

If we look directly at specific types of cancer tumors, then the localization of carcinoma in the liver makes a person die in agony due to multiple bleedings. Death from lung cancer also causes significant pain due to the fact that the patient begins to choke, vomit blood, after which an epileptic attack occurs and the patient dies. In the case of the patient, he also feels excruciating pain in the abdomen, in addition to this he is tormented by a headache. Laryngeal cancer patients also feel pain before they die. With this localization, the person also experiences severe pain in the corresponding area.

Important! Do not forget that the described symptoms are eliminated by doctors with the help of special analgesics, and before death - narcotic drugs, so in some cases it is possible to achieve an almost complete reduction in pain until it disappears.

Thus, the question “is it painful to die from cancer” can most likely be answered in the negative, since modern medicine has all the means to help reduce the patient’s pain.

Is it painful to die of old age?

According to medical research, people in old age experience a feeling of relief when they die. Only 1/10 of those surveyed feel fear before death. Just before death, old people feel discomfort, pain and complete apathy towards everything. When dying, people begin to see hallucinations and can “talk” to the dead. As for physical sensations, dying is painful only due to difficulty breathing.

Most old people can die in their sleep, and this death is not associated with severe pain and physical suffering.

Does it hurt to die from?

The physical sensations of a person dying due to taking an excessive amount of a drug depend primarily on the type of medication and the individual characteristics of the body. In fact, death occurs due to the development of severe intoxication of the body, and before death a person may experience pain due to pain in the abdomen. In addition, he experiences dizziness, nausea and vomiting.

An exceptional case would be a person who has taken an excessive dose of a potent sedative, since the consequences of such an act will be the onset of a deep coma and the shutdown of all instinctive defense mechanisms. In view of this, a person passes into another world directly in a dream and does not feel pain.

Is it painful to die from a stroke?

Because it can occur in different areas of the brain, a person's experience of death may also vary. If the motor center has been affected, weakness or paralysis may occur in a particular limb.

The general picture of a person’s feelings about death is usually as follows:

• He hears strange voices or sounds;
• I want to sleep;
• Confused mind;
• Severe headache;
• General weakness.

Some patients who have suffered may also die in their sleep or fall into a deep coma.

Is it painful to die from a heart attack?

In the heart, due to a failure in blood circulation, sudden changes in pressure occur, which is felt by a person as severe pain in the area behind the sternum. In addition, the blood supply to all organs is disrupted, which also causes pain - in particular, blood stagnates in the lungs and swelling of the latter occurs. The patient experiences difficulty breathing and general weakness of the body. In the first minutes, when blood stops flowing to the brain and hypoxia begins, the person will also experience a severe headache.

However, as a rule, during such an attack, a person may lose consciousness almost immediately, since the organs are not supplied with blood in the normal manner. Without medical assistance, a person in this condition can live no more than 5 minutes without feeling pain.

Does it hurt to die from a bullet?

It all depends primarily on the place where the bullet hit and its caliber. If a bullet pierces the brain, then very often death occurs almost instantly, and the organ shuts down faster than the person has time to feel anything. In other situations, as a rule, first a person feels a sharp jolt, then a certain warmth in the body, and only then severe pain. After a few minutes, a painful shock occurs, when pain is no longer felt due to the body’s defense mechanisms being turned on, and the person loses consciousness. If medical care is not provided, he dies from blood loss, but there is no physical suffering.

Does it hurt to die from a fall?

Death from falling from a great height occurs almost instantly - within a few seconds or minutes. The sensations largely depend on the position in which the person landed and on the surface on which he fell. If you land on your head, death occurs instantly, and the only thing that can be experienced in this case is psychological panic during the flight.

Death due to a fall occurs due to multiple fractures, rupture of internal organs and large blood loss. In the first seconds after the fall, a person experiences severe pain from the impact, then weakness occurs due to developing hypoxia and loss of consciousness.

Is it painful to die from blood loss?

The time of death in this case depends on the caliber of the damaged vessels. In particular, if the walls of the aorta are destroyed, the person dies almost instantly, without experiencing pain.

Losing a lot of blood, a person does not feel pain. When bleeding, he first experiences dizziness, heaviness in the body and weakness. Gradually, strong thirst is added to these feelings. Eventually, due to insufficient blood supply, the person may lose consciousness and die.

Is it painful to die from cold?

In severe frost conditions, a person can die for quite a long time, but will not experience pain. Being in the cold for a long time, a person first experiences severe trembling and body aches. Gradually, he also begins to lose memory and the ability to recognize the faces of loved ones. Then severe weakness sets in and, as a rule, people simply fall into the snow. The slow speed of blood flow in the brain provokes hallucinations. Severely narrowed capillaries on the skin can suddenly expand their lumen to create a surge of heat, which is why people often try to take off their clothes at this moment due to the feeling of “hotness”. After this, the person loses consciousness and dies as if “in his sleep.”

Is it painful to die from AIDS?

Since death in this case does not arise from AIDS itself, but from a disease that the body cannot cope with, the sensations before death may vary. Most often this is cytomegalovirus, liver cirrhosis, tuberculosis, developing against the background of AIDS. However, death can also occur from ordinary bronchitis.

Physical sensations will depend entirely on the disease that the body cannot overcome. It is painful for a person to die only if he is sick with serious diseases of the internal organs. For example, if death occurs from tuberculosis, the patient will experience severe pain in the chest area, breathing and heartbeat may be impaired, and may also occur. In cases where death occurs due to cirrhosis of the liver, the patient may experience excruciating pain in the abdomen and right hypochondrium.

Conclusion

To summarize the above, we can say that it is more painful for people to die psychologically. Only in some cases does a person experience severe pain before death. Most often, people find it difficult to accept the fact of dying.

Video

Blood loss - a pathological process that occurs as a result of bleeding and is characterized by a complex set of pathological disorders and compensatory reactions to a decrease in the volume of circulating blood and hypoxia caused by a decrease in the respiratory function of the blood.

Etiological factors of blood loss:

Violation of the integrity of blood vessels (wound, damage by a pathological process).

Increased vascular wall permeability (VWP).

Decreased blood clotting (hemorrhagic syndrome).

There are 3 stages in the pathogenesis of blood loss: initial, compensatory, terminal.

Initial. BCC decreases - simple hypovolemia, cardiac output decreases, blood pressure drops, and circulatory hypoxia develops.

Compensatory. A complex of protective and adaptive reactions is activated, aimed at restoring bcc, normalizing hemodynamics, and oxygen supply to the body.

Terminal stage blood loss can occur due to insufficiency of adaptive reactions associated with serious diseases, under the influence of unfavorable exogenous and endogenous factors, extensive trauma, acute massive blood loss exceeding 50-60% of the blood volume and the absence of therapeutic measures.

In the compensatory stage, the following phases are distinguished: vascular reflex, hydremic, protein, bone marrow.

Vascular reflex phase lasts 8–12 hours from the onset of blood loss and is characterized by spasm of peripheral vessels due to the release of catecholamines by the adrenal glands, which leads to a decrease in the volume of the vascular bed (“centralization” of blood circulation) and helps maintain blood flow in vital organs. Due to the activation of the renin-angiotensin-aldosterone system, the processes of reabsorption of sodium and water in the proximal tubules of the kidneys are activated, which is accompanied by a decrease in diuresis and water retention in the body. During this period, as a result of an equivalent loss of blood plasma and formed elements, a compensatory flow of deposited blood into the vascular bed, the content of red blood cells and hemoglobin per unit volume of blood and the hematocrit value remain close to the original (“hidden” anemia). Early signs of acute blood loss are leukopenia and thrombocytopenia. In some cases, an increase in the total number of leukocytes is possible.

Hydremic phase develops on the 1st–2nd day after blood loss. It manifests itself by the mobilization of tissue fluid and its entry into the bloodstream, which leads to restoration of plasma volume. “Dilution” of blood is accompanied by a progressive decrease in the number of red blood cells and hemoglobin per unit volume of blood. Anemia is normochromic, normocytic in nature.

Bone marrow phase develops on the 4th–5th day after blood loss. It is determined by the intensification of erythropoiesis processes in the bone marrow as a result of overproduction by the cells of the juxtaglomerular apparatus of the kidneys, in response to hypoxia, of erythropoietin, which stimulates the activity of the committed (unipotent) erythropoiesis precursor cell - CFU-E. The criterion for sufficient regenerative capacity of the bone marrow (regenerative anemia) is an increase in the content of young forms of erythrocytes (reticulocytes, polychromatophils) in the blood, which is accompanied by a change in the size of erythrocytes (macrocytosis) and cell shape (poikilocytosis). It is possible that red blood cells with basophilic granularity may appear, and sometimes single normoblasts in the blood. Due to increased hematopoietic function of the bone marrow, moderate leukocytosis develops (up to 12×10 9 /l) with a shift to the left to metamyelocytes (less often to myelocytes), the number of platelets increases (up to 500×10 9 /l or more).

Protein compensation is realized due to the activation of proteosynthesis in the liver and is detected within a few hours after bleeding. Subsequently, signs of increased protein synthesis are recorded within 1.5-3 weeks.

Types of blood loss:

According to the type of damaged vessel or chamber of the heart:

arterial, venous, mixed.

By volume of lost blood (from bcc):

light (up to 20-25%), moderate (25-35%), severe (more than 35-40%).

According to the time of onset of bleeding after injury to the heart or vessel:

Primary – bleeding begins immediately after injury.

Secondary – bleeding is delayed in time from the moment of injury.

According to the place of bleeding:

External – hemorrhage into the external environment.

Internal - hemorrhage in the body cavity or organs.

The outcome of bleeding is also determined by the state of the body's reactivity - the perfection of adaptation systems, gender, age, concomitant diseases, etc. Children, especially newborns and infants, endure blood loss much more severely than adults.

A sudden loss of 50% of blood volume is fatal. Slow (over several days) blood loss of the same volume of blood is less life-threatening, since it is compensated by adaptation mechanisms. Acute blood loss up to 25–50% of the volume of blood volume is considered life-threatening due to the possibility of developing hemorrhagic shock. In this case, bleeding from the arteries is especially dangerous.

Restoration of erythrocyte mass occurs within 1–2 months, depending on the amount of blood loss. At the same time, the reserve fund of iron in the body is consumed, which can cause iron deficiency. Anemia in this case acquires a hypochromic, microcytic character.

The main dysfunctions of organs and systems during acute blood loss are presented in Fig. 1

Figure 1. – Main dysfunctions of organs and systems during acute blood loss (according to V.N. Shabalin, N.I. Kochetygov)

Continued bleeding leads to depletion of the body's adaptive systems involved in the fight against hypovolemia - develops hemorrhagic shock. In this case, the protective reflexes of the macrocirculatory system are no longer sufficient to ensure adequate cardiac output, as a result of which systolic pressure quickly drops to critical levels (50-40 mm Hg). The blood supply to the organs and systems of the body is disrupted, oxygen starvation develops and death occurs due to paralysis of the respiratory center and cardiac arrest.

The main link in the pathogenesis of the irreversible stage of hemorrhagic shock is decompensation of blood circulation in the microvasculature. Disruption of the microcirculatory system occurs already in the early stages of the development of hypovolemia. Prolonged spasm of capacitive and arterial vessels, aggravated by a progressive decrease in blood pressure with incessant bleeding, sooner or later leads to a complete stop of microcirculation. Stasis sets in, and aggregates of red blood cells form in the spasmed capillaries. The decrease and slowdown in blood flow that occurs in the dynamics of blood loss is accompanied by an increase in the concentration of fibrinogen and globulins in the blood plasma, which increases its viscosity and promotes the aggregation of red blood cells. As a result, the level of toxic metabolic products increases rapidly and becomes anaerobic. Metabolic acidosis is compensated to a certain extent by respiratory alkalosis, which develops as a result of reflexively occurring hyperventilation. Severe disturbances in vascular microcirculation and the entry into the blood of under-oxidized metabolic products can lead to irreversible changes in the liver and kidneys, and also have a detrimental effect on the functioning of the heart muscle even during a period of compensated hypovolemia.

Measures for blood loss

Treatment for blood loss is based on etiotropic, pathogenetic and symptomatic principles.

Anemia

Anemia(literally – anemia, or general anemia) is a clinical and hematological syndrome characterized by a decrease in hemoglobin content and/or the number of red blood cells per unit volume of blood. Normally, the content of erythrocytes in peripheral blood in men averages 4.0-5.0 × 10 12 / l, in women - 3.7- 4.7 × 10 12 / l; hemoglobin level is 130-160 g/l and 120-140 g/l, respectively.

Etiology: acute and chronic bleeding, infections, inflammation, intoxication (salts of heavy metals), helminthic infestations, malignant neoplasms, vitamin deficiencies, diseases of the endocrine system, kidneys, liver, stomach, pancreas. Anemia often develops with leukemia, especially in its acute forms, and with radiation sickness. In addition, pathological heredity and disorders of the body’s immunological reactivity play a role.

General symptoms: pallor of the skin and mucous membranes, shortness of breath, palpitations, as well as complaints of dizziness, headaches, tinnitus, discomfort in the heart area, severe general weakness and fatigue. In mild cases of anemia, general symptoms may be absent, since compensatory mechanisms (increased erythropoiesis, activation of the functions of the cardiovascular and respiratory systems) provide the physiological need of tissues for oxygen.

Classification. The existing classifications of anemia are based on their pathogenetic characteristics, taking into account the characteristics of the etiology, data on the content of hemoglobin and red blood cells in the blood, the morphology of red blood cells, the type of erythropoiesis and the ability of bone marrow to regenerate.

Table 1. Classification of anemia

Criteria	Types of anemia
I. For reason	Primary Secondary
II. By pathogenesis	Posthemorrhagic Hemolytic Dyserythropoietic
III. By type of hematopoiesis	Erythroblastic Megaloblastic
IV. According to the ability of the bone marrow to regenerate (by the number of reticulocytes)	Regenerative 0.2-1% reticulocytes Aregenerative (aplastic) 0% reticulocytes Hyporegenerative< 0,2 % ретикулоцитов Hyperregenerative > 1% reticulocytes
V. By color index	normochromic 0.85-1.05 hyperchromic >1.05 hypochromic< 0,85
VI. By red blood cell size	Normocytic 7.2 - 8.3 µm Microcytic:< 7,2 мкм Macrocytic: > 8.3 - 12 µm Megalocytic: > 12-15 µm
VII. According to the severity of development	chronic