stages of anesthesia. Ether anesthesia

Means affecting the central nervous system

Drugs for anesthesia.

Substances that cause surgical anesthesia include. Narcosis is a reversible depression of the central nervous system, which is accompanied by loss of consciousness, loss of sensitivity, a decrease in reflex excitability and muscle tone.

Means for anesthesia inhibit the transmission of nerve impulses in the synapses of the central nervous system. Synapses of the central nervous system have unequal sensitivity to narcotic substances. This explains the presence of stages in the action of drugs for anesthesia.

Stages of anesthesia:

1st stage of analgesia (stunning)

2. stage of excitation

3. stage of surgical anesthesia

1st level – superficial anesthesia

2nd level light anesthesia

3rd level deep anesthesia

4th level ultra-deep anesthesia

4. stage of awakening or agonal.

Depending on the route of administration, there are: inhaled and non-inhaled drugs.

Inhalation drugs.

Enter through the respiratory tract.

These include:

Volatile liquids - ether for anesthesia, halothane (halothane), chloroethyl, enflurane, isoflurane, sevoflurane.

Gaseous substances - nitrous oxide, cyclopropane, ethylene.

It is an easily controlled anesthetic.

volatile liquids.

Ether for anesthesia- colorless, transparent, volatile liquid, explosive. Highly active. Irritates the mucous membrane of the upper respiratory tract, depresses respiration.

stages of anesthesia.

Stage 1 - stunning (analgesia). The synapses of the reticular formation are inhibited. main feature- confusion, decreased pain sensitivity, impaired conditioned reflexes, unconditioned reflexes are preserved, breathing, pulse, blood pressure are almost unchanged. At this stage, short-term operations can be performed (opening an abscess, phlegmon, etc.).

Stage 2 - excitement. The synapses of the cerebral cortex are inhibited. Inhibitory influences of the cortex on the subcortical centers are switched on, excitation processes predominate (the subcortex is disinhibited). "Rebellion of the subcortex". Consciousness is lost, motor and speech excitement (sing, swear), muscle tone increases (patients are tied). Unconditioned reflexes - cough, vomiting - intensify. Respiration and pulse are quickened, blood pressure is increased.

Complications: reflex respiratory arrest, secondary respiratory arrest: spasm of the glottis, retraction of the tongue, aspiration of vomit. This stage of the ether is very pronounced. It is impossible to operate at this stage.

Stage 3 - surgical anesthesia. Inhibition of synapses of the spinal cord. Unconditioned reflexes are inhibited, muscle tone decreases.

The operation starts at level 2, and is carried out at level 3. The pupils will be slightly dilated, almost do not react to light, the tone of the skeletal muscles is sharply reduced, blood pressure decreases, the pulse is faster, breathing is less, rare and deep.

An overdose can occur if the dosage of the narcotic substance is incorrect. And then the 4th level develops - super-deep anesthesia. The synapses of the centers of the medulla oblongata - respiratory and vasomotor - are inhibited. Pupils are wide, do not react to light, breathing is shallow, pulse is frequent, blood pressure is low.

When breathing stops, the heart may still work for a while. Resuscitation begins, tk. there is a sharp depression of respiration and blood circulation. Therefore, anesthesia must be maintained at stage 3, level 3, not brought to level 4. Otherwise, the agonal stage develops. With the correct dosage of narcotic substances and the cessation of their administration develops Stage 4 - awakening. Restoration of functions goes in reverse order.

With ether anesthesia, awakening occurs in 20-40 minutes. Awakening is replaced by a long post-anesthetic sleep.

During anesthesia, the patient's body temperature decreases, metabolism is inhibited. Decreased heat production . After ether anesthesia, complications may occur: pneumonia, bronchitis (ether irritates the respiratory tract), degeneration of parenchymal organs (liver, kidneys), reflex respiratory arrest, cardiac arrhythmias, damage to the conduction system of the heart.

Fluorothane - (halothane) - colorless, transparent, volatile liquid. Non-combustible. Stronger than ether. Mucous membranes are not irritating. The arousal stage is shorter, awakening is faster, sleep is shorter. Side effect- dilates blood vessels, lowers blood pressure, causes bradycardia (atropine is administered to prevent it).

Chloroethyl- stronger than ether, causes easily controlled anesthesia. It comes on quickly and passes quickly. Flaw- small breadth of narcotic action. It has a toxic effect on the heart and liver. Use for round anesthesia(short anesthesia when opening phlegmon, abscesses). Widely used for local anesthesia, applied to the skin. Boils at body temperature. Cools tissues, reduces pain sensitivity. Apply for superficial anesthesia during surgical operations, with myositis, neuralgia, sprains, muscles. It is impossible to overcool tissues, because. may be necrosis.

With the introduction of narcotic substances into the body, a regular staging has been established, which is most clearly manifested during ether anesthesia. Therefore, it is the stages of ether anesthesia that are methodically used in practical anesthesiology as a standard.

Of the proposed classifications, the Guedel classification is most widely used..

The first stage is the stage of analgesia

It usually lasts 3-8 minutes. Characterized by gradual depression, and then loss of consciousness. Tactile and temperature sensitivity, as well as reflexes, are preserved, but pain sensitivity is sharply reduced. This allows you to perform short-term surgical operations at this stage (roush anesthesia).

In the stage of analgesia, 3 phases are separated:

first phase- the beginning of euthanasia, the code is not yet complete analgesia and amnesia;
second phase- phase of complete analgesia and partial amnesia;
third phase- phase of complete analgesia and amnesia.

The second stage is the stage of excitation

Begins immediately after loss of consciousness, lasts 1-5 minutes. It is characterized by speech and motor excitation by an increase in muscle tone, pulse rate and blood pressure against the background of lack of consciousness.. Its presence is associated with the activation of subcortical structures.

Third stage - surgical (stage of anesthesia sleep)

It occurs 12-20 minutes after the start of anesthesia, when, as the body is saturated with anesthetic, inhibition deepens in the cerebral cortex and subcortical structures. Clinically, the phase is characterized by a loss of all types of sensitivity, reflexes, a decrease in muscle tone, a moderate slowing of the pulse, and hypotension.

In the surgical stage, 4 levels are distinguished:

first level surgical stage - (III 1) - the level of movement of the eyeballs. Against the background of restful sleep, muscle tone and reflexes are preserved. The eyeballs make slow circular movements. Pulse and blood pressure at baseline;
second level surgical stage (III 2) - the level of the corneal reflex. The eyeballs are motionless, the pupils are constricted, the reaction to light is preserved, but the corneal and other reflexes are absent. Muscle tone is reduced, hemodynamics is stable. Breathing is even, slow;
third level surgical stage (III 3) - the level of pupil dilation. The pupil expands, its reaction to the light sharply weakens. Sharply reduced muscle tone. The pulse quickens, a moderate decrease in blood pressure begins to appear. Costal breathing weakens, diaphragmatic breathing predominates, shortness of breath up to 30 per minute;
fourth level surgical stage (III 4) level of diaphragmatic breathing - should not be allowed in clinical practice, as it is a sign of overdose and a harbinger of death. The pupils are sharply dilated, there is no reaction to light, the pulse is thready, blood pressure is sharply reduced. Breathing diaphragmatic, superficial, arrhythmic. If the supply of the narcotic substance is not stopped, paralysis of the vascular and respiratory centers occurs and the agonal stage develops with clinical signs of respiratory and circulatory arrest.

The range of anesthetic concentrations, starting from the dose required to achieve stage III 1 - III 2 of anesthesia, and ending with a toxic dose, is called the anesthesia corridor, the greater its width, the safer anesthesia is.

During the operation, the depth of general anesthesia should not exceed the level III 1 - III 2, and only for a short time is it possible to deepen it to III 3.

The fourth stage is the stage of awakening

It occurs after the anesthetic supply is turned off and is characterized by a gradual restoration of reflexes, muscle tone, sensitivity and consciousness, in reverse order, displaying the stages of general anesthesia. Awakening lasts from several minutes to several hours, depending on the patient's condition, duration and depth of anesthesia. The excitation phase is not expressed, but the whole stage is accompanied by sufficient analgesia.

Thus, at present, surgical operations are performed in the third stage of anesthesia (level III 1 - III 2), and short-term interventions can also be performed in the first stage - analgesia.

Fluorotan (halothane, fluotan, narcotan)

A powerful halogen-containing anesthetic, 4-5 times stronger than ether. Causes a rapid onset of anesthesia (unlike ether, with virtually no excitation phase) and rapid awakening. It does not irritate the mucous membranes, inhibits the secretion of the salivary glands, causes bronchodilator, ganglioblocking and muscle relaxant effects.

The negative point is the depressive effect of the drug on the cardiovascular system (depression of myocardial contractility, hypotension).

Methoxyflurane (pentran, inhalan)

Halogen-containing anesthetic with a powerful analgesic effect with minimal toxic effects on the body. At high dosage and prolonged anesthesia, a negative effect on the heart, respiratory system and kidneys is revealed. It is possible to use for autoanalgesia: the patient, with preserved consciousness, inhales methoxyflurane vapor from a special evaporator to achieve analgesia, the deepening of anesthesia leads to muscle relaxation, which does not allow holding the inhaler. Inhalation of the anesthetic stops and awakening occurs. Then the analgesia is repeated again.

Etran (enflurane) - fluorinated ether

It has a powerful narcotic effect, causes rapid induction and rapid awakening. Stabilizes hemodynamic parameters, does not depress breathing, liver and kidney function, has a pronounced muscle relaxant effect. Etran increases cerebral blood flow and intracranial pressure, so it is used with caution in neurosurgical patients. Mask anesthesia with etranome is used for small short-term operations.

Isoflurane (foran)

Isoflurane is used for monoanesthesia and in combined anesthesia. It is indicated for induction anesthesia in children and for monoanesthesia.

Fluorothane, etran, isoflurane are most commonly used in combined general anesthesia, usually to enhance nitrous oxide.

See general anesthesia

Saenko I. A.

Sources:

Nursing guide / N. I. Belova, B. A. Berenbein, D. A. Velikoretsky and others; Ed. N. R. Paleeva.- M.: Medicine, 1989.
Zaryanskaya V. G. Fundamentals of resuscitation and anesthesiology for medical colleges (2nd ed.) / Series "Secondary vocational education" .- Rostov n / D: Phoenix, 2004.
Barykina N.V. Nursing in surgery: textbook. allowance / N. V. Barykina, V. G. Zaryanskaya.- Ed. 14th. - Rostov n/a: Phoenix, 2013.

Regulation of the depth and duration of general anesthesia is possible, but for this it is necessary to determine what stage of anesthesia the patient is currently in.

The stages of anesthesia in animals and humans always develop in a regular manner, and they are specific for each drug or their combinations. The action of all anesthetics is fundamentally the same.

The classical concept of "anesthesia clinic" (manifestations of signs of anesthesia, cited earlier in the literature) has undergone significant changes in meaning due to the use in practice of several drugs of multidirectional action simultaneously, complementing each other. This makes it difficult to assess the depth of anesthesia and its adequacy to surgical trauma. The clinical picture is described in detail on the example of inhalation anesthesia with ether. There are four main clinical stages of anesthesia. Let's consider stages I and III.

In stage I - stages of analgesia(intoxication, stadium incipiens, hypnotic phase - according to V. S. Galkin), the anesthetized patient loses orientation in the environment. He gradually falls into a drowsy state, from which he can be easily aroused by a loud sound. At the end of this stage, consciousness is turned off and analgesia occurs.

Stage I of anesthesia is characterized by a gradual darkening of consciousness, which, however, is not completely turned off. Tactile, temperature sensitivity and reflexes are preserved, pain sensitivity is sharply weakened (hence the name of the stage). Pupils are the same as before anesthesia or slightly enlarged, react to light. Pulse and breathing are somewhat quickened. In the stage of analgesia, short-term surgical operations and interventions are performed (incision, opening, reduction of dislocation). It corresponds to the concept of "stunning" (raush anesthesia). With ether anesthesia in combination with relaxants and other drugs at this stage, you can perform large operations, including intrathoracic ones.

With continued anesthesia, stage II occurs - excitation(stadium excitationis), when all physiological processes are activated: noticeably excited, noisy breathing, rapid pulse, all types of reflex activity are intensified. At this stage, inhibition develops in the cerebral cortex of the brain, resulting in inhibition of conditioned reflex activity and disinhibition of the subcortical centers.

The patient's behavior resembles a strong degree of alcoholic intoxication: the subconscious is turned off, motor excitation is pronounced, accompanied by an increase in muscle tone. The veins of the neck are filled, the jaws are compressed, the eyelids are closed, the pupils are dilated, the pulse is rapid and tense, blood pressure is increased, cough and gag reflexes are enhanced, breathing is rapid, short-term respiratory arrest (apnea) and involuntary urination are possible.

III stage - sleep stage, or tolerant(stadium tolerans, surgical, endurance stage) - begins due to the development of inhibition in the cortex and subcortex. Excitation stops, physiological functions stabilize. In practice, all anesthetics are selected so that this stage is the longest.

The activity of the centers of the medulla oblongata is preserved. Pain sensitivity disappears first on the back, then on the limbs, chest, abdomen. The state of the pupil is very important in this period: if the pupil is narrow and does not respond to light, this indicates the correct course of anesthesia. The expansion of the pupil and the appearance of a reaction to light precedes the awakening of the patient; Pupil dilation in the absence of reaction to light is the first important signal of threatening respiratory arrest.

Important indicators of the depth of anesthesia, along with the pupillary reflex, are changes in respiration, blood circulation, skeletal muscle tone, the condition of the mucous membranes and skin. An important role here is played by the results of special studies (if it is possible to conduct them): encephalography, oximetry, electrocardiography, etc. In stage III, different authors distinguish 3 ... 4 levels.

Surface level III stage (III-1 - level of eyeball movement) is characterized by the fact that the movement of the eyeballs is preserved, the pupils are constricted, they react to light. Only surface reflections are missing. Breathing is even, quickened, the pulse is somewhat quickened, blood pressure is normal, the skin is pink. The patient is in a state of calm even sleep, corneal, pharyngeal-laryngeal reflexes are preserved and muscle tone is somewhat reduced. You can perform short-term and low-traumatic operations.

Intermediate level III stage (III-2 - level of corneal reflex) is characterized by the fact that there is no movement of the eyeballs, the pupils are constricted, the reaction to light is preserved. Breathing is slow. Blood pressure and pulse are normal. Sometimes there is a short pause after exhalation. Reflex activity and muscle tone disappear, hemodynamics and respiration are satisfactory. It is possible to perform operations on the abdominal organs without the use of muscle relaxants.

On deep (3rd) level III stage (III-3 - pupil dilation level) the toxic effect of the ether is manifested - the pupils gradually expand, their reaction to light fades, the conjunctiva is moist. The rhythm and depth of breathing is disturbed, costal breathing weakens, diaphragmatic breathing predominates. Tachycardia increases, the pulse is somewhat quickened, blood pressure slightly decreases. The muscle tone is sharply reduced (atony), only the tone of the sphincters is preserved. The skin is pale. This level is acceptable for a short time with obligatory assisted breathing.

On 4th level III stage (III-4 - level of diaphragmatic breathing) the maximum inhibition of physiological functions is manifested; pupils are dilated, there is no reaction to light, the cornea is dry. Paralysis of intercostal muscles progresses, costal breathing is absent, contractility of the diaphragm decreases, diaphragmatic breathing is speeded up, superficial. Blood pressure decreases (hypotension), the skin is pale or cyanotic. Sphincters are paralyzed.

As anesthesia deepens, IV agonal stage(stadium agonalis). There is a paralysis of the respiratory and vasomotor centers: breathing is superficial, intermittent with long periods of apnea, up to a complete stop; arrhythmia, fibrillation and cardiac arrest are consistently observed; pulse first thready, then disappears; blood pressure drops rapidly and death occurs.

Under the action of other anesthetics, these same stages are expressed somewhat differently. For example, with intravenous administration of barbiturates in stage I, the patient quickly falls asleep calmly, breathing is slightly depressed, laryngeal and pharyngeal reflexes are increased, and hemodynamics is stable. In stage II, some dilation of the pupils is distinguished, reflex activity is preserved, respiratory arrhythmia appears, sometimes up to a short-term apnea, there may be motor reactions to pain. In stage III, the reaction to pain completely disappears, moderate muscle relaxation is observed, breathing becomes shallow, myocardial function is somewhat depressed, resulting in hypotension. With further strengthening of anesthesia with barbiturates, apnea and asystole are observed. This also happens with the rapid introduction of these drugs in high concentrations.

It is impossible and unnecessary to describe the clinical manifestation of anesthesia for all drugs and their combinations. The clinical picture of inhalation anesthesia with ether most fully reflects all stages, and on its basis it is possible to trace and evaluate the body's response to other drugs in each specific case.

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All materials on the site are prepared by specialists in the field of surgery, anatomy and specialized disciplines.
All recommendations are indicative and are not applicable without consulting the attending physician.

Author: Averina Olesya Valerievna, Candidate of Medical Sciences, pathologist, lecturer at the Department of Pathological Anatomy and Pathological Physiology

Today, no surgical operation is performed without adequate anesthesia. In some cases, there is a need to eliminate not only the sensitivity at the site of intervention, but also to turn off the patient's consciousness, as well as to relax the muscles. In such a situation, general anesthesia comes to the aid of surgeons, which has several varieties and is provided with a wide list of medicines and additional equipment, including for monitoring the vital functions of the operated person.

Anesthetic support of any operation is its most important component, without which it is impossible to achieve a positive result of treatment. In many ways, modern operative surgery is due precisely to the development of knowledge in the field of anesthesiology, which made possible large-scale abdominal operations used in abdominal surgery, oncology, urology, etc.

The phrase “general anesthesia”, which has firmly entered the everyday life of the average person, is not used by anesthesiologists, since it does not reflect the essence of the anesthesia procedure itself and does not carry any meaning at all. Another name for this type of anesthetic management is considered correct - general anesthesia. General - because drugs act primarily on the central nervous system, due to which not only deep anesthesia is achieved, but also a short-term lack of consciousness and memory for what happened in the operating room.

General anesthesia is not only the elimination of pain sensitivity. In the process of its implementation, the patient loses consciousness for some time, the muscles can be relaxed, and then the anesthesia procedure will also require artificial ventilation of the lungs - multicomponent anesthesia. Depending on the route of drug administration, inhalation anesthesia is distinguished, when drugs are administered through the respiratory organs, and non-inhalation anesthesia, when drugs are injected into a vein.

General anesthesia (anesthesia) accompanies the most varied in duration and scope of interventions on the organs of the abdominal cavity, small pelvis, and the musculoskeletal system. Plastic surgery often requires just such a method of anesthesia due to the traumatic nature of the interventions.

The correct conduct of general anesthesia is a complex task that requires an expert anesthesiologist to have deep knowledge of the pathogenetic mechanisms of the development of a wide variety of pathologies, dosages and features of the use of many drugs, as well as speed of decision-making in case of unforeseen reactions or sudden complications.

For many patients, the need for general anesthesia is even more frightening than the intervention itself, because it is quite difficult to predict how the body will react to the introduction of toxic anesthetics, and in case of emergency operations it is completely impossible.

Regardless of the method of administration of drugs, general anesthesia requires careful preparation of the patient and his comprehensive examination, since insufficient assessment of contraindications, the presence of severe concomitant diseases, elderly or childhood can adversely affect the consequences of surgical treatment.

It is no secret that not only errors in anesthesia, but also the individual characteristics of the patient's body can lead to tragedy when a small and short-term operation ends in the death of the cerebral cortex, severe intractable anaphylactic shock and death of the patient.

However, even the likely risks of anesthesia and frequent complications do not make it possible to refuse anesthesia, because this will be tantamount to refusing surgical treatment in principle. In order for the operation to be painless and without consequences from the action of anesthetics, anesthesia should be carried out by a competent, experienced specialist, taking into account all possible risk factors and the individual characteristics of the patient's body.

The anesthesiologist is the specialist whom the patient sees only a few times before and after the operation, but not a single surgeon can do without him. It depends on him how the patient will feel during and after the intervention, therefore it is important for the anesthesiologist to provide absolutely all information known to the patient about the medications taken, reactions to anesthesia in the past, the presence of allergies, chronic diseases of internal organs.

Indications and contraindications for general anesthesia

Indications for general anesthesia are limited by the need for surgical intervention. The depth of anesthesia depends on the planned operation and its trauma, the expected duration, the degree of muscle relaxation, the establishment of artificial lung ventilation and other features of surgical treatment.

The main goal of general anesthesia is an adequate level of pain relief and the absence of consciousness, which eliminates the effect of being present at the operation, as in the case of spinal or local anesthesia. Anesthesia should be deep enough for comfortable operation, and at the same time, should not be deeper than an acceptable and safe level.

Contraindications to general anesthesia are absolute only in the case of elective operations, when it is possible to either correct the patient's condition or choose another method of anesthesia. In emergency operations, when it comes to saving the patient's life, general anesthesia is performed in any case.

The following are considered to be an obstacle to the conduct of general anesthesia in a planned manner:

Diseases of the internal organs and the endocrine system in the stage of decompensation;
Arrhythmias regardless of the causative factor;
Severe course of bronchial asthma;
Postponed myocardial infarction or stroke in the next six months;
Acute alcohol, drug intoxication;
A full stomach is a relative contraindication.

In pediatric practice, the need for anesthesia is treated very carefully. If the operation can be postponed to a later date, then it will be temporarily abandoned. It is safer to carry out anesthesia for children who have reached the age of four. In emergency cases, there is no choice, and anesthetics are administered to babies even in the neonatal period, carefully calculating the safe dosage.

Stages of general anesthesia

The drugs used for anesthesia have a complex mechanism of action, they can cause peculiar changes in organs that fit into several phases, corresponding to the degree of tissue saturation with anesthetics. The use of combinations of anesthetics allows not only to reduce their toxic effect due to a lower dose, but also to make the introduction and exit from anesthesia more comfortable for the patient.

According to the depth of anesthesia, there are several stages of anesthesia:

stage of analgesia.
Excitation.
Surgical anesthesia.
Awakening.

To the first stage pain sensitivity in the nerve centers of the brain is blocked. The patient is still conscious, but as if stunned, may be inhibited, less often - shows anxiety. In the stage of analgesia, there is an increase in the pulse, an increase in muscle tone is possible, pain sensitivity disappears. Further introduction of anesthetics will lead to a deepening of anesthesia. The stage of analgesia is sufficient for short-term manipulations - drainage of abscesses, some invasive examination methods, etc. The duration of the first stage of general anesthesia is only a few minutes.

As the drugs are further administered, the patient's consciousness disappears, however, motor reactions intensify, which is associated with the excitation of the subcortical brain centers. Against the background of absent consciousness, motor excitation, an increase in muscle tone, erratic movements of the limbs, and even attempts to get up and leave the operating room on their own are noted.

In the stage of excitement respiration and pulse become more frequent, an increase in blood pressure, reddening of the skin, dilated pupils, increased production of mucus by the bronchial glands, sweating, salivation and lacrimation are characteristic. In this phase, vomiting is possible with the risk of aspiration of the contents of the stomach, reflex respiratory arrest, severe arrhythmia and death.

Unlike the first stage, which allows for minor interventions without additional deepening of anesthesia, second stage the action of anesthetics is not suitable for any manipulations and requires continued saturation of tissues with drugs. Its duration is on average 7-15 minutes.

Third phase of general anesthesia - surgical, which has several levels depending on the concentration of anesthetics and the depth of anesthesia. At this stage, the patient calms down, the correct rhythm and frequency of breathing and heartbeats are restored, the pressure is close to normal numbers. Complete loss of sensitivity and loss of consciousness allow a variety of operations to be performed at the stage of surgical anesthesia.

Surgical anesthesia has 4 levels:

Operations are carried out in stage I or II of surgical anesthesia, and after they are completed, the patient is gradually removed from this state - the awakening stage. The anesthesiologist stops administering medications, the anesthesia phases are reversed.

Preparation for General Anesthesia

At the stage of preparation for treatment under general anesthesia, the main role is played by the anesthesiologist, who finds out the maximum amount of information regarding all diseases that can somehow affect the course of anesthesia. It is important to ask when the last exacerbations of chronic pathology were, what the patient is constantly treated for, whether there are allergies, whether there were operations in the past that required anesthesia, and what was the patient's reaction to it.

With planned treatment, the doctor has time to correct existing disorders, bring the pathology into a state of compensation. Particular attention is paid to the oral cavity, since caries can be regarded as a possible source of infection.

It is important to assess the mental status of the patient, as many anesthetics can exacerbate the course of chronic mental illness. In schizophrenia, anesthetics that cause hallucinations are contraindicated. In the case of psychosis, surgery under anesthesia is impossible in principle.

Finding out the allergic history, the anesthesiologist will definitely ask if there are any allergies not only to drugs, but also to food, household chemicals, and plants. In case of an allergy to anything, the risk of anaphylactic reactions to anesthetics increases, therefore, high doses of antihistamines (suprastin, diphenhydramine) are used to prevent them.

For the anesthesiologist, the anatomical features of the structure of the face and chest, the length of the neck, past injuries or diseases that deformed the cervical and thoracic spine, and the degree of development of subcutaneous fat are also important. Some features can change the nature of the proposed anesthesia and the list of drugs administered, make it impossible to intubate the trachea, and limit the depth of anesthesia to its first stage.

One of the basic rules of the preparatory stage is the sanitation and cleansing of the digestive tract. The patient's stomach is washed with a probe (according to indications), on the eve of the operation, food and drink are canceled for 10-12 hours, a cleansing enema is prescribed.

Preliminary medical preparation is carried out from the evening before the operation. It is aimed at normalizing the psycho-emotional state, suppressing the tone of the vagus nerve. At night, phenazepam is injected into the muscle, with strong excitement, emotionally labile subjects are shown sedatives.

40 minutes before the scheduled intervention, narcotic analgesics are injected into the muscle or subcutaneously. Atropine helps to reduce salivation and suppress the gag reflex. After premedication, the anesthesiologist revises the oral cavity, removable dental structures are removed.

Features of different types of anesthesia

After the preparatory stage, immediately before the operation, the anesthesiologist begins the introduction of the operated person into anesthesia, carefully controlling the pulse, pressure, and breathing. Only with the permission of the anesthesiologist, the surgeon will be able to proceed with tissue incisions and manipulations in the foci of pathology, body cavities, and internal organs.

General anesthesia can be:

Intravenous - drugs are injected into a vein;
Inhalation - anesthetics are inhaled.

Intravenous anesthesia similar to short-term sleep with loss of pain sensitivity. Its advantage is the speed of achieving anesthesia, the lack of arousal, when the patient simply quickly falls asleep. The disadvantage of intravenous anesthesia is its short duration, therefore, for long-term operations, combinations of drugs and constant maintenance of their required concentration are needed, which limits intravenous anesthesia during long-term interventions.

The drugs most commonly used for general intravenous anesthesia are thiopental sodium and hexenal. These funds contribute to rapid falling asleep without a phase of excitation, and then to a rapid exit from narcotic sleep. Anesthetic solutions are injected into the vein slowly, controlling the patient's reaction to them.

A single application of these drugs provides anesthesia for about a quarter of an hour. If necessary, anesthetics are administered to the maximum possible dosage, constantly measuring the pressure and pulse of the operated person. The doctor monitors the pupils and reflexes.

Against the background of the introduction of sodium thiopental, respiratory arrest is possible, therefore, the presence of artificial pulmonary ventilation in the operating room is a prerequisite for general anesthesia.

General intravenous anesthesia, when only one drug is administered, is possible with short-term interventions, the duration of which is no more than 15-20 minutes (reduction of dislocations, curettage of the uterus, opening of abscesses, suturing after childbirth, etc.).

Ketamine is injected into a muscle or vein as a general anesthetic. This drug can be remembered by patients for its hallucinogenic effect, which manifests itself at the end of anesthesia or upon exit from it. Ketamine promotes tachycardia and high blood pressure, therefore it is contraindicated in hypertension, but is administered in shock.

Inhalation anesthesia involves the inhalation of anesthetics that are easily vaporized or gaseous - halothane, chloroform, nitrous oxide. Getting into the respiratory operated through the tube, anesthetics maintain a state of sleep.

Benefits of inhalation anesthesia it is considered a smaller dose of a narcotic drug compared to intravenous, there is no risk of getting the contents of the stomach, blood into the trachea, the patency of which is provided by an endotracheal tube.

This type of anesthesia is successfully used in interventions on the head and neck, it is one of the stages of combined anesthesia in traumatic abdominal operations. The combination of intravenous and inhaled drugs allows the use of smaller doses of drugs, which reduces their toxic effects. The analgesic effect and disabling consciousness are achieved by a combination of narcotic drugs, if necessary, muscle relaxation is done by muscle relaxants.

General anesthesia is carried out in three stages:

Throughout the course of general anesthesia, the anesthesiologist carefully monitors the state of blood circulation, regularly determines blood pressure and pulse. In case of pathology of the heart and blood vessels, operations on the organs of the chest, constant monitoring of the activity of the heart is necessary.

Providing the patient with oxygen and the nature of metabolic processes against the background of the introduction of toxic anesthetics are shown by studies of blood pH, the degree of saturation with oxygen, the level of carbon dioxide, etc., which are carried out throughout the operation. All indicators are recorded by the nurse in a special card, which also includes the names and dosages of the drugs administered, the reaction to them, and the complications that have arisen.

Video: general anesthesia - broadcast from the operating room

Complications and effects from general anesthesia

Patients' fears about anesthesia are not unfounded. This event carries the risk of quite serious complications, the most dangerous of which is the death of the patient. Nowadays, complications are rare, although it is impossible to exclude them completely, especially in patients with a number of concomitant complications.

Anesthesia is dangerous at any stage of anesthesia due to the action of drugs or a violation of the technique of its implementation. The most common consequence of it is vomiting, which is fraught with the ingress of stomach contents into the respiratory tract, which can provoke a spasm of the bronchi and larynx.

Passive ingestion of food masses is possible with deep general anesthesia without intubation or after the introduction of muscle relaxants before the introduction of the endotracheal tube. Subsequent pneumonias can cause death.

To prevent the above complications, gastric emptying is performed, and in some cases, the probe is left for the entire period of anesthesia. Vomiting is also possible upon awakening, so the patient's head is turned to the side and his condition is carefully monitored.

Respiratory effects are associated with:

Difficulty in the airway;
Malfunction of artificial ventilation equipment;
Retraction of the tongue covering the larynx, pathology of the dento-jaw apparatus.

With the introduction of a laryngoscope, injuries to the teeth and structures of the larynx are possible. Violation of the intubation technique can lead to the installation of a tube into the esophagus, bronchus, in rare cases, it comes out of the trachea, bends. These complications are caused by technical errors in the actions of the anesthetist.

The consequences are also provoked by the negative effect of anesthesia on the circulatory system:

Hypotension up to collapse;
Heart rhythm disorders - tachycardia, extrasystole, deadly ventricular fibrillation;
hypertension;
myocardial infarction;
Pulmonary edema.

The most dangerous complication asystole, which occurs with insufficiently careful monitoring of the patient, technical errors, incorrect calculation of dosages of anesthetics, the presence of severe concomitant pathology. This condition requires urgent resuscitation.

The nervous system also experiences the effects of anesthetics. So, the patient may have a slight decrease in temperature, and after the use of halothane, chills appear. A serious consequence is cerebral edema with deep and prolonged anesthesia.

A serious complication can be an allergy to injected drugs in the form of anaphylactic shock, which is accompanied by severe hypotension, swelling of the mucous membranes of the respiratory tract, bronchospasm and requires urgent therapeutic measures.

The consequences for the body after any type of anesthesia are different. If the anesthesia was adequate, there were no complications, then the patient recovers quickly and does not experience any difficulties due to anesthesia. Rarely, problems arise due to the need to use high doses of drugs, technical errors, complications.

Very rarely, patients wake up before the end of the operation, and this complication may not be noticed by the anesthesiologist. If relaxants are introduced, then the patient will not be able to give at least some signal. At best, he does not feel pain, at worst, he feels it, hears everything that happens in the operating room.

Pain shock can lead to death, and if the operated person copes with the sensations during the intervention, then after the operation, psychological problems are almost inevitable - severe neuroses, depression, which will have to be dealt with for a long time and with the participation of a psychotherapist.

Some patients note memory impairment, forgetfulness, difficulty in performing habitual intellectual tasks. These cases are usually associated with frequent anesthesia, excessively deep anesthesia, individual reaction to drugs. It is clear that any anesthesia is potentially dangerous, but it is generally accepted that general anesthesia can be done as many times as required by the disease. If the anesthesiologist is sufficiently qualified, the patient is examined, the possible risks are taken into account, then even multiple anesthesia can pass safely and without consequences.

After general anesthesia, patients recover differently. It depends on the individual characteristics of the nervous system, the drugs used, the duration of anesthesia. Some drugs (ketamine, for example) can cause colorful hallucinations and excitement during the period of recovery from anesthesia, after others, patients may notice a feeling of weakness, heaviness in the head, drowsiness, a feeling similar to alcohol intoxication. These symptoms usually disappear in the next few hours after coming out of anesthesia, completely disappearing by the evening of the day of the intervention.

Recovery after anesthesia includes early activation, the fight against pain in the first days after surgery, the prevention of thromboemblic complications. The sooner the patient leaves the clinic, the sooner the rehabilitation period will end and the sooner he will forget that anesthesia was performed at all. If the consequences were severe, then appropriate drug treatment of complications is prescribed, consultations of a psychotherapist are carried out, and if necessary, antidepressants are prescribed.

One of the most common myths about anesthesia is the widespread opinion among the inhabitants that anesthesia takes years of life and impairs intelligence. One can hardly agree with this. Anesthesia does not shorten life or impair brain activity, but severe pain or refusal of surgery may well cost a life.

In order for anesthesia to be successful, and this usually happens, it is important that it be carried out by a competent anesthesiologist who carefully monitors the patient's condition, has enough information about his diseases and strictly selects the names and dosages of drugs. It is believed that any anesthesia is well tolerated if properly administered by a qualified doctor. Don't panic if you need general anesthesia. This is a necessary and obligatory component of most operations, so it is pointless to refuse treatment out of fear.

Video: doctor about the types of anesthesia used during operations

Video: child under general anesthesia

Methods of anesthesia

When performing inhalation anesthesia, three main conditions must be met:

a) correct dosing of the anesthetic;

b) maintaining a sufficient concentration of O 2 in the inhaled mixture;

c) adequate removal of carbon dioxide from the body.

The anesthetic may be administered to the airways through a mask, an airway (nasopharyngeal method), a laryngeal mask, or an endotracheal tube.

In this case, one of four breathing circuits can be used:

1) open, in which the anesthetic enters the lungs along with the air inhaled from the atmosphere, and is excreted when exhaled into the atmosphere;

2) a semi-open circuit, when the patient inhales the anesthetic mixed with O 2 coming from the balloon, while exhalation occurs into the atmosphere;

3) a semi-closed circuit, in which part of the exhaled air goes into the atmosphere, and part, together with the anesthetic contained in it, after passing through the CO 2 absorber, returns to the circulation system and, therefore, enters the patient with the next breath;

4) a closed circuit, characterized by the fact that the gas-narcotic mixture recirculates in the inhalation anesthesia apparatus with the included CO 2 absorber in complete isolation from the atmosphere.

Maintenance of anesthesia with any method of supplying inhalation anesthetics to the respiratory tract of an animal is currently very rarely carried out only by inhalation agents. More often they are combined with non-inhalation. Despite the perfection of modern dosing units of inhalation devices, during anesthesia, constant monitoring of its level is necessary in order to correct it in a timely manner. When using only inhalation anesthetics, in contrast to non-inhalation agents, residual post-anesthetic depression is short-lived. This facilitates the observation and care of the animal in the immediate postoperative period.

When animals are anesthetized with the use of both inhalation and non-inhalation agents for anesthesia, the depression of the central nervous system occurs unevenly, as a result of which 4 stages are distinguished:

I STAGE - the stage of analgesia. After absorption of an inhalation agent for anesthesia into the blood, inhibition of the reticular formation of the brain stem and cerebral cortex develops, accompanied by a decrease in pain sensitivity. The animal's consciousness is gradually suppressed (the animal is still in contact during this period, it can react to external stimuli), unconditioned reflexes are preserved during this period, and conditioned reflexes can be inhibited. Respiration, pulse and arterial pressure are almost not changed. By the end of the stage of analgesia in animals, pain sensitivity is completely lost, and therefore, at this stage of anesthesia, some surgical procedures can be performed (for example, opening abscesses, phlegmon).

II STAGE - the stage of excitation. It develops with a further deepening of the effect of the drug on the cerebral cortex. In animals at this stage of anesthesia, muscle tone sharply increases, uncontrolled motor excitation develops, and they can howl. In addition, during this period of anesthesia in animals, cough and gag reflexes increase, and therefore vomiting often occurs. Respiration and pulse are quickened, blood pressure is increased. According to I.P. Pavlov, the cause of excitation at this stage is the switching off of the inhibitory influences of the cerebral cortex on the subcortical centers. At the same time, according to the figurative expression of I.P. Pavlov, a “rebellion of the subcortex” arises.

STAGE III - the stage of surgical anesthesia. The inhibitory effect of ether on the brain is even more deepened and spreads to the spinal cord. The phenomena of excitation pass. Unconditioned reflexes are inhibited, muscle tone decreases. In this stage, 4 periods are distinguished (Figure 1):

1 period III stage of anesthesia- anesthesia becomes deep, breathing is uniform, reflexes, although still preserved, are significantly weakened, glandular secretion and muscle tone begin to decrease.

2 period III stage of anesthesia- muscle tone sharply weakens, reflexes begin to disappear, except for the eye, the pupil is narrowed to the limit, the eyeball is turned down.

3 period III stage of anesthesia- there comes a complete, devoid of reflexes anesthesia (except for the cornea) with even, but shallow breathing, which becomes more and more superficial and can only be adjusted by inhalation of carbon dioxide. The pupil is somewhat dilated, the corneal reflex begins to weaken, the secretion of the glands is sharply limited, it still remains only in ruminants. Muscle tone disappears, tongue sinks.

4 period III stage of anesthesia- the most dangerous period of anesthesia - breathing becomes superficial and jerky, cyanosis of the mucous membranes sets in, blood pressure drops. The rotation of the eyeball disappears, and it takes its usual position, the cornea is dry, the pupil is dilated. Life-threatening events occur.

Figure 1. Scheme of the course of the stages of ether anesthesia

STAGE IV - recovery stage occurs when the drug is discontinued. The functions of the central nervous system are restored. Recovery takes place in the reverse order of their oppression.

In the case of an overdose of narcotic substances, stage IV of anesthesia is designated as the stage of paralysis. It develops as a result of the action of the drug on all parts of the central nervous system, including the respiratory and vasomotor centers of the medulla oblongata, and therefore there is a sharp depression of respiration and blood circulation. Breathing becomes rare and superficial. The pulse is frequent, weak filling. Arterial pressure is sharply reduced. There is cyanosis of the skin and mucous membranes. The pupils are maximally dilated. Death from drug poisoning occurs with symptoms of respiratory arrest and heart failure.

Table 1 Characteristics of the stages of anesthesia

State of functional systems	Stun stage	Excitation stage	anesthesia	Toxic stage (overdose)
Consciousness	Oppressed (confused)	Turned off	Turned off	Turned off
pain sensitivity	blunted	Absent	Absent	Absent
Skeletal muscle tone	Saved	Promoted	Downgraded	Dramatically reduced
Arterial pressure	Normal	Upgraded	Downgraded	Dramatically reduced
Pulse	Normal	Frequent	Rhythmic, good filling	Frequent, weak filling
Breath	Normal	Irhythmic	Rhythmic, deep, subdued	Irhythmic, superficial (up to a stop)
Pupils	Constricted	Expanded	Constricted	Expanded
Pupillary reactions to light	Eat	Eat	Eat	No
Corneal reflex	Eat	Eat	No	No

Table 2 Advantages and disadvantages of funds