Stages of anesthesia. Ether anesthesia

Drugs affecting the central nervous system

Anesthetic agents.

These include substances that cause surgical anesthesia. Narcosis is a reversible depression of central nervous system functions, which is accompanied by loss of consciousness, loss of sensitivity, decreased reflex excitability and muscle tone.

Anesthetics inhibit the transmission of nerve impulses at synapses in the central nervous system. CNS synapses have unequal sensitivity to drugs. This explains the presence of stages in the action of anesthesia.

Stages of anesthesia:

1. stage of analgesia (stunning)

2. stage of excitement

3. stage of surgical anesthesia

Level 1 – superficial anesthesia

Level 2 light anesthesia

Level 3 deep anesthesia

Level 4 ultra-deep anesthesia

4. stage of awakening or agonal.

Depending on the route of administration, they distinguish between inhaled and non-inhaled narcotic drugs.

Inhaled drugs.

Administered through the respiratory tract.

These include:

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

Gaseous substances – nitrous oxide, cyclopropane, ethylene.

This is an easily administered anesthesia.

Volatile liquids.

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

Stages of anesthesia.

Stage 1 – stunning (analgesia). Synapses of the reticular formation are inhibited. Main sign– confusion, decreased pain sensitivity, violation of 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. The inhibitory influences of the cortex on the subcortical centers are activated, and excitation processes predominate (the subcortex is disinhibited). “Revolt of the subcortex.” Consciousness is lost, motor and speech arousal (singing, swearing), muscle tone increases (patients are tied up). Unconditioned reflexes increase - coughing, vomiting. Breathing and pulse are increased, blood pressure is increased.

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

Stage 3 – surgical anesthesia. Inhibition of spinal cord synapses. Unconditioned reflexes are inhibited and muscle tone decreases.

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

If the dosage of a drug is incorrect, an overdose may occur. And then level 4 develops - ultra-deep anesthesia. The synapses of the centers of the medulla oblongata - respiratory and vasomotor - are inhibited. The pupils are wide, do not react to light, breathing is shallow, pulse is fast, blood pressure is low.

When breathing stops, the heart may still beat for some time. Resuscitation begins, because there is a sharp depression of breathing and blood circulation. Therefore, anesthesia must be maintained at stage 3, level 3, and not brought to level 4. Otherwise, the agonal stage develops. With the correct dosage of narcotic substances and stopping their administration, it develops Stage 4 – awakening. Restoration of functions proceeds in the reverse order.

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

During anesthesia, the patient's body temperature decreases and metabolism is inhibited. Heat production is reduced . Complications that may occur after ether anesthesia include: 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.

Ftorotan – (halothane) – colorless, transparent, volatile liquid. Non-flammable. Stronger than ether. Does not irritate mucous membranes. The arousal stage is shorter, awakening is faster, sleep is shorter. Side effect– dilates blood vessels, reduces blood pressure, causes bradycardia (atropine is administered to prevent it).

Chloroethyl– stronger than ether, causes easily controlled anesthesia. Comes quickly and goes quickly. Flaw– small breadth of narcotic action. Has a toxic effect on the heart and liver. Used for Rausch anesthesia(short anesthesia for opening phlegmons, abscesses). Widely used for local anesthesia, applied to the skin. Boils at body temperature. Cools tissues, reduces pain sensitivity. Apply for superficial pain relief during surgical operations, myositis, neuralgia, sprained ligaments and muscles. Do not overcool tissues, because there may be necrosis.

When narcotic substances are introduced into the body, a natural phasing pattern has been established, which is most clearly manifested during ether anesthesia. Therefore, it is precisely the stages of ether anesthesia that are methodically used in practical anesthesiology as a standard.

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

The first stage is the analgesia stage

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 short-term surgical operations (rausch anesthesia) to be performed at this stage.

The stage of analgesia is divided into 3 phases:

first phase- the beginning of euthanasia, when there is still no 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 excitement

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

The third stage is surgical (anesthesia sleep stage)

Occurs 12-20 minutes after the onset 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 loss of all types of sensitivity, reflexes, decreased muscle tone, moderate decrease in pulse rate and hypotension.

In the surgical stage there are 4 levels:

first level surgical stage - (III 1) - 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) - 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 are stable. Breathing is even, slow;
third level surgical stage (III 3) - level of pupil dilation. The pupil dilates, its projection to the light sharply weakens. Muscle tone is sharply reduced. The pulse quickens and 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 is diaphragmatic, shallow, 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 stages III 1 - III 2 of anesthesia, and ending with the toxic dose, is called the anesthetic corridor; the wider its width, the safer the anesthesia.

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

The fourth stage is the stage of awakening

Occurs after the anesthetic supply is turned off and is characterized by a gradual restoration of reflexes, muscle tone, sensitivity and consciousness, displaying the stages of general anesthesia in reverse order. Awakening lasts from several minutes to several hours, depending on the patient’s condition, duration and depth of anesthesia. The excitation phase is not pronounced, but the entire 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 be performed in the first stage - analgesia.

Ftorotan (halothane, fluotane, narcotan)

A potent halogen-containing anesthetic, 4-5 times stronger than ether. Causes a rapid onset of anesthesia (unlike ether, practically without an excitation phase) and rapid awakening. Does not irritate the mucous membranes, inhibits the secretion of the salivary glands, causes bronchodilator, ganglion-blocking and muscle relaxant effects.

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

Methoxyflurane (pentran, inhalan)

Halogen-containing anesthetic with a powerful analgesic effect with minimal toxic effects on the body. With high dosage and prolonged anesthesia, a negative effect on the heart, respiratory system and kidneys is detected. It can be used for autoanalgesia: the patient, while maintaining consciousness, inhales methoxyflurane vapor from a special evaporator to achieve analgesia; deepening anesthesia leads to muscle relaxation, which makes it impossible to hold the inhaler. The inhalation of the anesthetic stops and awakening occurs. Then the analgesia is repeated again.

Ethrane (enflurane) - fluorinated ether

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

Isoflurane (foran)

Isoflurane is used for monoanesthesia and combined anesthesia. Indicated for induction of anesthesia in children and for monoanesthesia.

Fluorotane, ethrane, and isoflurane are most often used in combined general anesthesia, usually to enhance nitrous oxide.

See general anesthesia

Saenko I. A.

Sources:

Nurse's Handbook for Care/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/d: Phoenix, 2013.

Regulating 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 naturally, and they are specific to each drug or their combinations. The action of all anesthetics is fundamentally the same.

The classic concept of “clinical anesthesia” (manifestations of signs of anesthesia, previously cited in the literature) has undergone significant changes in meaning due to the simultaneous use in practice of several drugs with multidirectional effects that complement 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 using 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 surrounding environment. He gradually falls into a dormant state, from which he can be easily awakened by a loud sound. At the end of this stage, consciousness turns off and analgesia occurs.

Stage I of anesthesia is characterized by a gradual blackout of consciousness, which, however, does not turn off completely. Tactile and temperature sensitivity and reflexes are preserved, pain sensitivity is sharply weakened (hence the name of the stage). The pupils are the same as before the onset of anesthesia or are slightly enlarged and react to light. Pulse and breathing are somewhat rapid. During the analgesia stage, short-term surgical operations and interventions are performed (incision, opening, reduction of dislocation). It corresponds to the concept of “stunning” (rausch anesthesia). With ether anesthesia in combination with relaxants and other drugs, major operations, including intrathoracic ones, can be performed at this stage.

As anesthesia continues, stage II occurs - excitation(stadium excitationis), when all physiological processes are activated: agitation is noticeable, noisy breathing, rapid pulse, all types of reflex activity intensify. At this stage, inhibition develops in the cerebral cortex, resulting in inhibition of conditioned reflex activity and disinhibition of subcortical centers.

The patient's behavior resembles a strong degree of alcohol intoxication: the subconscious is turned off, motor excitation is pronounced, accompanied by increased muscle tone. The veins of the neck are full, the jaws are clenched, the eyelids are closed, the pupils are dilated, the pulse is rapid and tense, blood pressure is increased, cough and gag reflexes are strengthened, breathing is rapid, short-term cessation of breathing (apnea) and involuntary urination are possible.

Stage III - 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, and abdomen. The condition of the pupil is very important during this period: if the pupil is narrow and does not react to light, this indicates the correct course of anesthesia. Pupil dilation and the appearance of a reaction to light precede the patient's awakening; dilation of the pupil in the absence of a reaction to light serves as the first important signal of a threatening respiratory arrest.

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

Superficial level of stage III (III-1 - level of movement of the eyeballs) is characterized by the fact that the movement of the eyeballs is preserved, the pupils are constricted, and react to light. Only superficial reflexes are absent. Breathing is even, rapid, pulse is slightly increased, blood pressure is normal, skin is pink. The patient is in a state of calm, even sleep, the corneal, pharyngolaryngeal reflexes are preserved and muscle tone is slightly reduced. Short-term and low-traumatic operations can be performed.

Average 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, and the reaction to light is preserved. Breathing is slow. Blood pressure and pulse are normal. Sometimes after exhalation there is a slight pause. Reflex activity and muscle tone disappear, hemodynamics and breathing are satisfactory. Abdominal surgery can be performed without the use of muscle relaxants.

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

On 4th level III stage (III-4 - level of diaphragmatic breathing) extreme depression of physiological functions is manifested; the pupils are dilated, there is no reaction to light, the cornea is dry. Paralysis of the intercostal muscles progresses, costal breathing is absent, contractility of the diaphragm decreases, diaphragmatic breathing is rapid and shallow. Blood pressure decreases (hypotension), the skin is pale or cyanotic. Sphincter paralysis occurs.

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

With 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 are stable. In stage II, the pupils are slightly dilated, reflex activity is preserved, respiratory arrhythmia appears, sometimes leading to short-term apnea, and 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 intensification of anesthesia with barbiturates, apnea and asystole are observed. This also happens with rapid administration of these drugs in high concentrations.

It is neither possible nor necessary to describe the clinical manifestations 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 monitor and evaluate the body’s response to other drugs in each specific case.

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

Author: Averina Olesya Valerievna, candidate of medical sciences, pathologist, teacher of the department of pathological anatomy and pathological physiology

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

Anesthetic management of any operation is its most important component, without which it is impossible to achieve a positive treatment result. In many ways, modern operative surgery owes 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 become firmly established in everyday life, 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 the drugs act primarily on the central nervous system, due to which not only deep pain relief is achieved, but also a short-term absence of consciousness and memory of what happened in the operating room.

General anesthesia is not only about eliminating pain sensitivity. During 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 administration of drugs, a distinction is made between inhalational anesthesia, when drugs are administered through the respiratory system, and non-inhalation anesthesia - drugs are injected into a vein.

General anesthesia (anesthesia) accompanies interventions on the abdominal organs, pelvis, and musculoskeletal system that vary in duration and volume. Plastic surgery often requires this type of anesthesia due to the traumatic nature of the interventions.

Proper administration of general anesthesia is a complex task that requires a specialist anesthesiologist to have deep knowledge of the pathogenetic mechanisms of development of a wide variety of pathologies, dosages and features of the use of many medications, as well as quick decision-making in the event 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 the case of emergency operations, it is completely impossible.

Regardless of the method of drug administration, general anesthesia requires careful preparation of the patient and his comprehensive examination, since insufficient assessment of contraindications, the presence of severe concomitant diseases, old age or childhood can negatively 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-scale and short-term operation ends in the death of the cerebral cortex, severe intractable anaphylactic shock and the death of the patient.

However, even the probable risks of anesthesia and frequent complications do not make it possible to refuse anesthesia, because this would 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 must be performed by a competent, experienced specialist who takes into account all possible risk factors and the individual characteristics of the patient’s body.

An anesthesiologist is a specialist whom the patient sees only a few times before and after surgery, but no surgeon can do without him. It depends on 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 being taken, reactions to anesthesia in the past, allergies, chronic diseases of internal organs.

Indications and contraindications for general anesthesia

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

The main goal of general anesthesia is an adequate level of pain relief and absence of consciousness, which eliminates the effect of presence during the operation as in the case of spinal or local anesthesia. The anesthesia should be deep enough for the operation to be performed comfortably, 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 planned operations, when it is possible either to correct the patient’s condition or to choose a different method of anesthesia. During emergency operations, when it comes to saving the patient’s life, general anesthesia is performed in any case.

The following are considered obstacles to routine general anesthesia:

Diseases of internal organs and the endocrine system in the stage of decompensation;
Arrhythmias, regardless of the causative factor;
Severe bronchial asthma;
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, it will be temporarily abandoned. It is safer to administer anesthesia to children over the age of four. In emergency cases, there is no choice, and babies are given anesthetics even during the newborn period, carefully calculating the safe dosage.

Stages of general anesthesia

The drugs used for anesthesia have a complex mechanism of action and are capable of causing peculiar changes in organs that fall 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 induction and recovery from anesthesia more comfortable for the patient.

Based on the depth of anesthesia, there are several stages of anesthesia:

Analgesia stage.
Excitation.
Surgical anesthesia.
Awakening.

To the first stage pain sensitivity is blocked in the nerve centers of the brain. The patient is still conscious, but seems to be stunned, may be inhibited, and less often, shows anxiety. During the analgesia stage, an increase in heart rate is noted, muscle tone may increase, and pain sensitivity disappears. Further administration of anesthetics will lead to deepening of anesthesia. The analgesia stage 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, but motor reactions intensify, which is associated with excitation of the subcortical brain centers. Against the background of absent consciousness, motor agitation, increased 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 breathing and pulse become more frequent, characterized by increased blood pressure, redness of the skin, dilated pupils, increased mucus production by the bronchial glands, sweating, salivation and lacrimation. During this phase, vomiting with the risk of aspiration of gastric contents, reflex respiratory arrest, severe arrhythmia and death are possible.

Unlike the first stage, which allows for minor interventions without additional deepening of anesthesia, second stage the effect of anesthetics is not suitable for any manipulations and requires continued saturation of tissues with drugs. Its average duration is 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 heartbeat are restored, and the pressure is close to normal values. Complete loss of sensation and loss of consciousness allows a variety of operations to be performed during the stage of surgical anesthesia.

Surgical anesthesia has 4 levels:

The operations are carried out in stages I or II of surgical anesthesia, and after their completion the patient is gradually removed from this state - the awakening stage. The anesthesiologist stops administering medications, and the anesthesia phases proceed in the reverse order.

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 as much information as possible regarding all diseases that may in one way or another affect the course of anesthesia. It is important to ask when the last exacerbations of chronic pathology were, what the patient is constantly treated with, whether there are any allergies, whether there have been operations in the past that required anesthesia, and what the patient’s reaction to it was.

With planned treatment, the doctor has time to correct existing disorders and bring the pathology to 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 patient's mental status, as many anesthetics can aggravate chronic mental illness. In schizophrenia, anesthetics that cause hallucinations are contraindicated. In the case of psychosis, surgery under anesthesia is impossible in principle.

When finding out the allergy history, the anesthesiologist will definitely ask if there are allergies not only to medications, but also to food, household chemicals, and plants. If you are allergic to anything, the risk of anaphylactic reactions to anesthetics increases, so antihistamines in high doses (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 have deformed the cervical and thoracic spine, and the degree of development of subcutaneous fat are also important. Some features may change the nature of the intended anesthesia and the list of drugs administered, make tracheal intubation impossible, 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), everyone on the eve of the operation is stopped from eating and drinking for 10-12 hours, and a cleansing enema is prescribed.

Preliminary drug preparation is carried out the evening before the operation. It is aimed at normalizing the psycho-emotional state and suppressing the tone of the vagus nerve. At night, phenazepam is injected into the muscle; in case of severe anxiety, sedatives are indicated for emotionally labile subjects.

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

Features of different types of anesthesia

After the preparatory stage, immediately before the operation, the anesthesiologist begins introducing the patient under anesthesia, carefully monitoring the pulse, pressure, and breathing. Only with the permission of the anesthesiologist will the surgeon be able to begin tissue incisions and manipulations in 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 considered speed of achieving anesthesia, lack of excitement, when the patient simply quickly falls asleep. The disadvantage of intravenous anesthesia is that it is short-lived, so long-term operations require combinations of drugs and constant maintenance of the required concentration, which limits the use of intravenous anesthesia for long-term interventions.

The drugs most commonly used for general intravenous anesthesia are thiopental sodium and hexenal. These drugs promote rapid falling asleep without an arousal phase, and then a rapid recovery from drug-induced sleep. Anesthetic solutions are injected into the vein slowly, monitoring the patient's reaction to them.

A single use 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 patient being operated on. The doctor monitors the pupils and reflexes.

During the administration of sodium thiopental, respiratory arrest is possible, so the presence of an artificial pulmonary ventilation device in the operating room is a prerequisite for general anesthesia.

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

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

Inhalation anesthesia involves the inhalation of anesthetics that easily evaporate or are gaseous - fluorotane, chloroform, nitrous oxide. Entering the patient's respiratory tract through a tube, anesthetics maintain a state of sleep.

The advantage of inhalation anesthesia it is considered to be a smaller dose of a narcotic drug compared to an intravenous one, and there is no risk of stomach contents or blood getting into the trachea, the patency of which is ensured by an endotracheal tube.

This type of anesthesia is successfully used for interventions on the head and neck, and is one of the stages of combined anesthesia for traumatic abdominal operations. The combination of intravenous and inhaled drugs allows the use of smaller doses of drugs, which reduces their toxic effect. The analgesic effect and loss of consciousness are achieved by a combination of narcotic drugs; if necessary, muscle relaxants are used to relax muscles.

General anesthesia is carried out in three stages:

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

The provision of oxygen to the patient and the nature of metabolic processes against the background of the administration of toxic anesthetics are shown by studies of blood pH, the degree of oxygen saturation, carbon dioxide levels, etc., which are carried out throughout the entire 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 any complications that have arisen.

Video: general anesthesia - broadcast from the operating room

Complications and consequences of general anesthesia

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

Anesthesia is dangerous at any stage of anesthesia due to the effects of drugs or violation of the technique of its administration. The most common consequence is vomiting, which can cause stomach contents to enter the respiratory tract, which can cause spasm of the bronchi and larynx.

Passive ingestion of food masses is possible during deep general anesthesia without intubation or after the administration of muscle relaxants before insertion of the endotracheal tube. Pneumonia that occurs subsequently can cause death.

To prevent the complications described above, gastric emptying is performed, and in some cases the probe is left in place 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 airway patency;
Malfunction of artificial ventilation equipment;
Retraction of the tongue covering the larynx, pathology of the dentofacial apparatus.

When inserting a laryngoscope, injuries to teeth and laryngeal structures are possible. Violation of intubation technique can lead to the installation of a tube into the esophagus, bronchus, in rare cases it comes out of the trachea and becomes bent. These complications are caused by technical errors in the actions of the anesthesiologist.

Consequences are also provoked by the negative impact 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 is asystole, which occurs due to insufficiently careful monitoring of the patient, technical errors, incorrect calculation of anesthetic dosages, and the presence of severe concomitant pathology. This condition requires urgent resuscitation.

The nervous system also experiences the effects of anesthetics. So, the patient’s temperature may drop slightly, and after using fluorotane, chills appear. Cerebral edema during deep and prolonged anesthesia is considered a serious consequence.

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 medical measures.

The consequences for the body after any type of anesthesia are different. If pain relief was adequate and no complications arose, the patient recovers quickly and does not experience any difficulties due to the anesthesia. Problems rarely arise due to the need to use high doses of drugs, technical errors, or complications.

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

Painful shock can lead to death, and if the person being operated on copes with the sensations during the intervention, then after the operation, problems of a psychological nature 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, and difficulty performing habitual intellectual tasks. These cases are usually associated with frequent anesthesia, excessively deep anesthesia, and individual reactions 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 the disease requires. If the anesthesiologist is sufficiently qualified, the patient is examined, and possible risks are taken into account, then even repeated anesthesia can proceed safely and without consequences.

After general anesthesia, patients recover differently. This depends on the individual characteristics of the nervous system, the drugs used, and 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 note a feeling of weakness, heaviness in the head, drowsiness, a feeling similar to alcohol intoxication. These symptoms usually disappear within the next few hours after recovery from anesthesia, disappearing completely by the evening of the day of intervention.

Recovery after anesthesia includes early activation, combating pain in the first days after surgery, preventing thromboembolic 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 for complications is prescribed, a psychotherapist is consulted, and antidepressants are prescribed if necessary.

One of the most common myths regarding anesthesia is the widespread belief among ordinary people that anesthesia takes away years of life and impairs the intellect. One can hardly agree with this. Anesthesia does not shorten life or disrupt brain activity, but severe pain or refusal to operate may well cost your life.

In order for anesthesia to proceed safely, and this is usually what happens, it is important that it is 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 performed correctly by a qualified physician. Don't panic if you need general anesthesia. This is a necessary and mandatory component of most operations, so it makes no sense to refuse treatment out of fear.

Video: a doctor about the types of anesthesia used during operations

Video: child under general anesthesia

Methods of anesthesia

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

a) correct dosage of anesthetic;

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

c) adequate removal of carbon dioxide from the body.

The anesthetic can be delivered to the airway through a mask, airway (nasopharyngeal method), laryngeal mask or endotracheal tube.

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

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

2) a semi-open circuit, when the patient inhales an anesthetic mixed with O 2 coming from a balloon, and exhales 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, having passed through the CO 2 absorber, returns to the circulation system and, therefore, enters the patient with the next inhalation;

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

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

When anesthetizing animals using both inhalation and non-inhalation anesthetics, the depression of the central nervous system occurs unevenly, as a result of which 4 stages are distinguished:

STAGE I – stage of analgesia. After absorption of an inhaled anesthetic 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 depressed (the animal is still in contact during this period and can react to external stimuli), unconditioned reflexes are preserved during this period, but conditioned reflexes may be inhibited. Breathing, pulse and blood pressure are almost unchanged. By the end of the analgesia stage in animals, pain sensitivity is completely lost, and therefore, at this stage of anesthesia, some surgical procedures can be performed (for example, opening abscesses, phlegmons).

STAGE II – stage of excitation. It develops with further deepening of the drug’s effect 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, the cough and gag reflexes intensify, and therefore vomiting often occurs. Breathing and pulse are increased, 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, in the figurative expression of I.P. Pavlov, a “revolt of the subcortex” arises.

STAGE III – stage of surgical anesthesia. The inhibitory effect of ether on the brain deepens even more and spreads to the spinal cord. The phenomena of excitement pass. Unconditioned reflexes are inhibited and muscle tone decreases. At this stage there are 4 periods (Figure 1):

1 period of stage III anesthesia– anesthesia becomes deep, breathing is uniform, reflexes, although still preserved, are significantly weakened, gland 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 ones, the pupil is narrowed to the limit, the eyeball is turned down.

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

4 period III stage of anesthesia– the most dangerous period of anesthesia – breathing becomes shallow and jerky, cyanosis of the mucous membranes occurs, blood pressure drops. The rotation of the eyeball disappears, and it takes its normal position, the cornea is dry, the pupil is dilated. Life-threatening phenomena occur.

Figure 1. Scheme of the stages of ether anesthesia

STAGE IV – recovery stage occurs when the drug is stopped. The functions of the central nervous system are restored. Recovery occurs 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, resulting in a sharp depression of breathing and blood circulation. Breathing becomes rare and shallow. The pulse is frequent, weak filling. Blood pressure is sharply reduced. Cyanosis of the skin and mucous membranes is observed. The pupils are maximally dilated. Death from drug poisoning occurs due to respiratory arrest and heart failure.

Table 1 Characteristics of 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	Dulled	Absent	Absent	Absent
Skeletal muscle tone	Saved	Promoted	Demoted	Sharply reduced
Arterial pressure	Normal	Increased	Downgraded	Sharply reduced
Pulse	Normal	Frequent	Rhythmic, good filling	Frequent, weak filling
Breath	Normal	Irrhythmic	Rhythmic, deep, slow	Irrhythmic, superficial (to the point of stopping)
Pupils	Narrowed	Expanded	Narrowed	Expanded
Pupil reactions to light	Eat	Eat	Eat	No
Corneal reflex	Eat	Eat	No	No

Table 2 Advantages and disadvantages of funds