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Mechanical asphyxia

Hypoxia - oxygen starvation of organs and tissues, until the complete cessation of oxygen supply to the body.

Asphyxia is the state of the body when, along with a lack of oxygen, carbon dioxide accumulates in it.

Mechanical asphyxia arises from the action of an external mechanical factor.

According to the pace of development, hypoxia is divided into:

acute, developing and leading to death within seconds or several minutes,

subacute (a few hours),

chronic, lasting for months or even years.

As a rule, mechanical asphyxia is acute. Its entire course from the beginning to death falls within 6-8 minutes (the time during which the cerebral cortex dies).

The asphyxiation process begins with

reflex breath holding (up to 20-30 sec). If mechanical obstruction to breathing is not eliminated, then

inspiratory dyspnea phase - characterized by lengthening and intensification of inspiration due to irritation of the respiratory center by carbon dioxide accumulating in the blood. In this phase, blood pressure rises, heart activity becomes more frequent and intensifies, random movements of the limbs are possible. The duration of this phase is 40-60 seconds, after which it is replaced

expiratory dyspnea phase. Excessive carbon dioxide causes severe excitation of the respiratory and vasomotor centers. In this phase, exhalation prevails over inhalation. Short-term convulsive movements of individual muscle groups are observed. Involuntary excretion of feces, urine, and sperm may occur. Visible mucous membranes become cyanotic, sensitivity and reflexes are absent; 40-60 seconds after the onset of asphyxiation, consciousness is lost. Following this comes

the phase of short-term respiratory arrest (about 1 min), due to redirection of the vagus nerves and a decrease in the excitability of the respiratory center due to excessive accumulation of carbon dioxide in the blood. Blood pressure decreases. Short stop breathing is replaced last

phase of terminal breathing, manifested in the form of separate, irregular respiratory movements for 1-3 3-5 minutes. In this phase, there is a persistent fading of all reflexes, dilated pupils, muscle relaxation, a sharp drop in blood pressure. Severe cramps develop. After this, respiratory arrest occurs due to paralysis of the respiratory center. It should be noted that irregular heart contractions can be observed for some time (3-10 minutes).

If a person experiences an asphyxical state, then he has a number of complications that affect the functions of the central nervous system, cardiac activity, respiration, pain in the area of ​​compression, and with prolonged asphyxia - memory loss, convulsions.

Hanging is a mechanical asphyxia from squeezing the neck with a loop under the weight of a person’s body, sometimes only parts of the body. Hanging can be complete when the legs do not touch the ground, and incomplete - when sitting, half-sitting, lying down or in cases of touching the bent legs of the surface.

Hanging is usually in a loop, but in some cases neck compression occurs in a fork in a tree, a door and a pillar of a car, or lying on a hard crossbeam.

The loop from the neck is removed without untying the knot, and if necessary, cutting it away from it. After stitching, it is studied and described in detail by a forensic expert, and then surrendered to the investigator for the appointment of a forensic examination.

Strangulation furrow - a trace of compression by a loop on the skin of the neck - the main symptom in the study of a corpse in case of death from hanging.

In the study of the strangulation furrow, all its features should be identified and carefully described: location, direction, isolation, width, depth, density, color, relief, and its other individual characteristics and properties.

The fingerprint of the belt buckle with individual details, the pattern of the turns of the rope with the display of the knot and the fibers of the fabric on the surface can have individual value for identification.

The hanging in an upright position is indicated by the oblique direction of the furrow, usually located above the thyroid cartilage, openness and varying degrees of pressure: more on the side opposite the node, less on the sides. Sometimes discontinuity can take place not in the area of ​​the knot, but in other places, and can be explained by a collar or other part of the clothes that is restrained by the loop. On the other hand, a pale strip against the background of cadaveric spots, formed from compression by the edge of a tightly buttoned collar, can simulate a strangulation furrow.

For macroscopic determination of the intravital origin of the strangulation groove, a piece is cut from its area with a portion of intact skin. At the beginning of the autopsy, a skin flap with a portion of the groove and part of the unchanged skin is separated at the section table, separated from the underlying tissues, pulled onto a glass plate and examined for clearance. This is a test of N.S. Bocarius. When identifying areas of hemorrhage, especially in the infringement rollers, it allows you to pre-establish the intravital nature of the appearance of the furrow.

A sign of intravital hanging are hemorrhages and tears in the muscles of the neck with tension, especially in the places where they are attached to the sternum and collarbone. This is also evidenced by transverse tears with hemorrhages of the inner wall of the common carotid artery (Amyuss sign). In approximately half the cases, hanging cartilages of the larynx and hyoid bone are damaged with hemorrhage in the surrounding tissue.

During histological examination in the intravital strangulation sulcus, minor hemorrhages along its course are visible, especially in the ridges, the epidermal layer of the skin is sharply flattened, the papillary protrusions are absent, the stratum corneum is destroyed or completely absent. The fibrous layers of the skin itself are closely adjacent to each other, elastic fibers in the form of scraps. The vessels of the bottom of the furrow are compressed. In the lower and upper ridges there is an expansion and plethora of blood vessels.

With the posthumous origin of the strangulation furrow, all the macro- and microscopic features described above (with the exception of flattening of the skin layers), as well as reactive changes, are absent.

Hanging death comes from several factors. In addition to the cessation of (sometimes partial) air intake, which is facilitated by the posterior and upward displacement of the tongue, which closes the lumen of the larynx, compression of the vessels of the neck (carotid arteries and jugular veins) is important. Sometimes a fatal role is played by compression of the nerve trunks of the neck and the synocarotid node. A sharp compression of the neck, leading to a complex of changes, increases intracranial pressure and leads to loss of consciousness after 1-2 seconds, and then to the relaxation of the muscles and the cessation of breathing. However, in some cases, death occurs from primary cardiac arrest. Therefore, attempts at self-rescue are impossible. A rare exception is incomplete hanging and loose loop tightening.

When hanging during the investigation, the question of the nature of death is always decided. Most often this is suicide, however, there are cases and murders.

Loop suppression, another form of strangulation asphyxia, also leads to the formation of a furrow and to the same common signs of rapid death. The strangulation of the loop, in contrast to the hanging, usually occurs when tightening with an outside hand (less commonly with some kind of loop tightening mechanism) and therefore is a murder.

After identifying the strangulation furrow, in addition to determining its intravitality, the question of the origin of the furrow should be resolved: from hanging or from tightening the loop by hand. It should be reminded right away that with oxygen starvation and compression of blood vessels in the first seconds a person loses consciousness, his muscles relax. This eliminates the possibility of self-suppression, since for the onset of biological death, even from the action of a complex of factors, 3-5 minutes are needed.

Furrow from strangulation differs from that described above, arising from hanging. It is horizontal, located at different levels, is closed and is uniform in depth throughout. With strangulation, especially with a stiff loop, more often than when hanging, they find fractures of the hyoid bone, cartilage of the larynx, with extensive hemorrhage around. In such cases, it is especially necessary to carefully search for traces of the struggle, both at the scene of the incident and on the body. They will not be during infanticide by strangulation by a noose.

Strangulation by hands is always a murder, because it is impossible to strangle oneself in connection with the rapid loss of consciousness and muscle relaxation, which causes the neck compression to stop before death. Squeeze the neck with one or two hands. Depending on this, semilunar abrasions from nails or oval bruises from the fingertips form on the front or side surfaces of the neck. You can take into account that when strangled with the right hand, one damage is located on the right, and a greater number of them are on the left surface of the neck.
When squeezed by hands, damage will be observed on both sides. When the child’s neck is compressed, the lesions are located behind. However, with the victim's resistance, the damage does not have a specific shape. If there is any gasket on the neck, there may be no damage at all.

In this type of neck compression in all cases there are hemorrhages in the root of the tongue and fractures of the larynx, hyoid bone, and thyroid cartilage. Sometimes it’s important to pay attention to the direction of the fracture. A transverse fracture of the thyroid cartilage is formed by hitting a board edge, and not by strangulation. As a rule, there are other injuries on such corpses, indicating a fight and self-defense. It should be noted that neck compression can be a knee between the shoulder and forearm, which leaves no residue.

Compression asphyxia refers to asphyxiation from compression. It arises from the compression of only the chest or abdomen, but it occurs more effectively with simultaneous compression of the chest and abdomen, as it leads to limitation or cessation of breathing, impaired blood circulation. This usually happens during various accidents at a construction site, transport, during the destruction, collapse of buildings from earthquakes or explosions.

Asphyxia from closure.

Covering the openings of the mouth and nose with the palm or any soft objects. This method is often used for the purpose of murder, including infanticide, in which often use the hand, sometimes various tissues that are at hand. In rare cases, the closing of the mouth and nasal openings occurs in severely intoxicated drunks, patients with epilepsy during a seizure, or infants who find themselves face pressed to a soft bed. This also includes asphyxiation from “sprinkling” that occurs during breastfeeding, when the mother, while falling asleep, presses the infant’s mouth and nose with the mammary gland.

Closing the lumen of the respiratory tract with foreign bodies - the lumen of the larynx near the glottis, causing irritation of the upper throat nerve and rapid cardiac arrest, or the penetration of foreign bodies deeper into the larynx, up to the trachea and bronchi.

Often this happens in patients who are drunk, with a hasty meal or a sudden distraction. These are uncooked pieces of meat, fat, dentures, chewing gum. There is a known case when, in an argument, a drunken man tried to swallow a whole potato, which tightly closed the lumen of the larynx. But more often, the closure of the airway lumen occurs in children who take everything in their mouths: toys, nuts, screws, buttons, etc., as well as in cases of illness and coughing. Occasionally, such asphyxiation can be a murder when (especially in children) the entrance to the larynx is plugged. Rare cases of suicide are described by pushing a rolled-up tie, scarf, cotton wool into the mouth, but this is usually the result of an accident.

Closing the lumen of the respiratory tract with loose substances (sand, grain, flour, etc.). This happens during crashes, industrial accidents, often among drunk people or people who do not comply with safety rules. Diagnosis is to identify such foreign inclusions that block the airways. However, to eliminate errors, the expert, after opening the chest cavity, even before removing the chest organocomplex, opens the trachea, bronchi, examines the lungs in the section and cuts out pieces of them for histological examination. They are judged both by macroscopic examination, and when detecting particles in the alveoli of the lungs under microscopy. Bulk substances get in such cases and into the stomach when swallowed.

Vomiting closure of the airway is of particular importance in medical practice and in other accidents, especially in drunk people and children. The food contents from the stomach enter the respiratory tract, penetrating the bronchi and lungs, blocking access to air, causing asphyxiation. On examination, the lumens of the bronchi are filled with food masses, the lungs are lumpy upon examination, and foreign particles emerge from the surface of the incision when the lung tissue is compressed. But the main thing is microscopic evidence, in which microparticles of the contents of the stomach are noted in the alveoli. Such a picture can be when they get in life.

Closure of the lumen of the respiratory tract with aspirated blood. This is observed with fractures of the bones of the skull base, sometimes nasal bones, often with damage to the vessels of the neck. The flow of blood into the larynx is facilitated by the unnatural position of the body in the unconscious or drunk state of the wounded. Diagnosis is based on the detection of blood in the lungs. On examination, the lungs are colorful, that is, the dark areas alternate with the light, in the section they are full-blooded, a large amount of blood flows from the surface of the section. With a histological examination, the alveoli are filled with blood, dilated. As with other types of asphyxia, common signs of rapid death are noted.

Drowning (which used to be referred to asphyxiation chapter), as it turned out, does not always lead to death from oxygen starvation, but only in a third of cases.

A corpse extracted from water or other liquid is not always a corpse of a drowned man, most often during a murder in order to conceal a crime. Drowning most often occurs as a result of an accident, but can be used as suicide or murder. Therefore, inspection and assessment of damage is of utmost importance. Not only their character, tool and application mechanism are established, but also intravitality, because a number of them arise already in the water, accidentally when moving the corpse or using the screws of ships, blows of oars or when removing the corpses, causing damage by crabs, crabs, etc.

Types of Drowning

The classic true type of drowning is not always found. It is observed only in 20% of cases, occurs due to aspiration of the liquid, and is called the aspiration or wet type of drowning. Drowning is a form of violent death that occurs when a person is immersed in a liquid. It is caused by an acute violation of the functions of vital organs and systems; it is organized under the influence of various mechanisms. The morphological picture of drowning described above refers to the true type of drowning.

Asphyxic type of drowning (spastic), common signs of asphyxia are observed. In approximately 35% of cases of drowning, persistent laryngospasm occurs, which, under the influence of irritation of the laryngeal mucosa, closes the glottis, preventing the penetration of water into the respiratory tract, and therefore the term "dry drowning" exists.

Reflex type of drowning. In relatively rare cases (about 10%), when a person falls into extreme conditions and a psychogenic reaction develops (possibly with pathological changes in the body), sudden death occurs while the heart and breathing stop simultaneously. The diagnosis of this type is difficult, while there is a sharp pallor of the skin, sharp plethora, and signs of acute death.

A mixed type of drowning, characterized by both the phenomenon of aspiration and laryngospasm. Thus, in the diagnosis of drowning, one must bear in mind the various signs of drowning. It occurs in approximately 35% of cases.

Death in water - when a person suffering from cardiovascular diseases under the influence of fear or physical exertion in the water, death occurs and he is immersed in water already dead.

The signs of a corpse being in water, regardless of the cause of death, include maceration in the form of swelling and gradual detachment of the epidermis of the skin on the palmar surfaces of the hands and soles of the feet.

After 2-6 hours, the epidermis swells, acquires a grayish-white color.

By the 3-4th day of the corpse being in the water, swelling of the epidermis is well expressed on the entire skin of the corpse; especially the skin of the palmar surfaces - the "hand of the laundresses" changes.

By the 8-15th day, the epidermis gradually begins to separate from the skin itself, by the end of the first month, the skin on the hands is torn away together with the nails in the form of the so-called death gloves. The duration of the development of maceration is affected by the temperature of the water; in colder water, it comes slower, in warm - faster. The maceration process is accelerated in running water. Одежда, перчатки на руках и обувь задерживают развитие мацерации.

Через две недели вследствие разрыхления кожи начинается выпадение волос.

К концу первого месяца, особенно в теплой воде, может наступить полное облысение.

Контрольные вопросы

1. Повреждения. Понятие о травме. Особенности детского травматизма.

2. Классификация травм.

3. Виды ран и их клинические признаки.

4. Причины смерти при механических повреждениях.

5. Особенности повреждений, причиняемые острыми и тупыми предметами.

6. Транспортная травма.

7. Автомобильная травма.

8. Огнестрельные повреждения.

9. Действие высокой температуры.

10. Действие низкой температуры.

11. Электротравмы.

12. Механическая асфиксия.
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Механическая асфиксия

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