Induction of anesthesia and intubation (After sleep onset). Fundamentals of Anesthesiology

Before you go directly to the presentation of the period induction of anesthesia, we will indicate a number of important measures that the anesthesiologist must strictly perform, regardless of the nature and scope of the upcoming surgical intervention. Always, even if there is a short-term anesthesia, you need to have everything ready to carry out complex anesthesia, including resuscitation measures.

For this, before the patient will be admitted to the operating room, the anesthesiologist must carefully inspect his workplace, personally verify the presence of a sufficient amount of oxygen, nitrous oxide and other anesthetics, check the serviceability of anesthesia equipment, a laryngoscope, a suction vacuum system, gastric tubes, endotracheal tubes, urethral catheters, a set of masks, sterile systems for intravenous infusion of blood and blood substitutes, a set of syringes and needles, catheters for intravenous infusions, the availability of medications. It is imperative to check the functionality of the defibrillator, as well as the grounding of the operating table, anesthesia machine and all other electrical devices.

Anesthesiologist's clothes and underwear must be made of cotton fabric. This important rule, unfortunately, is often violated, especially by female anesthesiologists. Static electricity that accumulates in synthetic fabrics can cause explosions in operating rooms. It should be emphasized that, whenever possible, the anesthesiologist should use anesthetics that do not explode or ignite. However, this is not always and not always possible. Ether as an anesthetic is still widely used in many hospitals, although there is a clear trend towards its replacement by other anesthetics. It is important to remember that if a patient is undergoing general anesthesia or using explosive substances, then the surgeon should not use an electric knife or perform electrocoagulation under any circumstances.

Only after anesthetist The person conducting general anesthesia will personally verify the availability and functionality of anesthesia equipment, instruments and medications, and he will give instructions that the patient can be taken to the operating room. It is desirable and psychologically important that the anesthesiologist, who has already met the patient in advance, himself accompanies him from the ward to the operating room, with his presence instilling in the patient confidence in the successful outcome of the upcoming general anesthesia and operation. Experience shows that it is precisely this period - from the moment the patient is placed on a gurney and delivered to the operating room (including preparatory measures - application of electrocardiograph electrodes and electric shock, venipuncture, setting up a system for intravenous infusions) until the start of induction of anesthesia, which takes 10-15 minutes, is the culminating stressful moment. It is during this period that the adequacy of the premedication is assessed. With good organization, this period can be reduced to a minimum.

Induction anesthesia is the most responsible period of general anesthesia. By analogy with aviation, where the takeoff and landing of an aircraft are the most dangerous, in anesthesiology the periods of induction and recovery from anesthesia are considered as such. In terms of emotional intensity for the anesthesiologist, these periods, especially the period of induction of anesthesia, can perhaps be compared with the experiences of pilots, to whom people completely trust their lives.

Huge moral burden puts pressure on the shoulders of anesthesiologists during each induction of anesthesia, despite experience and many years of practice. In fact, in this short period, calculated in minutes, the anesthesiologist has to administer an ultra-short-acting anesthetic intravenously to turn off the patient’s consciousness, then a muscle relaxant and completely paralyze all striated muscles, at the same time transfer the patient to artificial respiration (injecting an oxygen-gas narcotic mixture from bag of the anesthesia machine through the mask into the patient's lungs), then stop artificial respiration for a short period, insert the laryngoscope, quickly and gently insert the endotracheal tube into the trachea, inflate the cuff on the tube, connect the latter to the adapter of the anesthesia machine and, resuming artificial ventilation, then proceed to a calmer period - the period of maintaining anesthesin.

The latter, again by analogy with aviation can be compared with the period when the autopilot is turned on after the aircraft has climbed to the appropriate altitude and the navigator has selected the desired course. There are many dangers during the period of induction anesthesia: impaired cardiac activity (up to ventricular fibrillation), a sharp drop in blood pressure, laryigo and bronchospasm, regurgitation, vomiting, inadequate gas exchange (hypoxia and hypercapnia), etc. Hence it is obvious that the choice of drugs for induction anesthesia and the methodology for its implementation should be carefully thought out by the anesthesiologist individually for each patient. There shouldn't be any template here.

The greatest distribution in our days received a non-inhalation intravenous route of induction of anesthesia. It attracted the attention of anesthesiologists, since with this method the stage of excitation is not clinically manifested. Among the drugs used for intravenous induction anesthesia, ultra-short-acting barbiturates are used - 1-2% solutions of hexnal or thiopental sodium. The (slow) administration of these drugs is stopped as soon as the patient loses consciousness. Usually, on average, 200-400 mg of drugs are consumed.

Has become widespread in recent years neuroleptanalgesia technique, in which droperidol (10-20 mg), fentanyl (0.2-0.4 mg), nitrous oxide with oxygen in a ratio of 2:1 or 3:1 are used to put the patient under anesthesia. There are also many supporters of the ataralyesia method, in which, instead of the antipsychotic droperndol, ataratna seduxen (diazepam) is used at a dose of 10-25 mg.

In pediatric anesthesiology for induction anesthesia purposes The mask inhalation method is widely used. Of the anesthetics, preference is given to fluorotane (0.5-2% by volume), with the help of which children are quickly, in 2-3 minutes, easily and calmly, without visible excitement, put into anesthesia. Ketamine anesthesia also deserves attention. The drug is administered intramuscularly (5-7 mg/kg) or intravenously (2 mg/kg).

For short-term anesthesia Propanidide (Epontol, Sombrevin) is widely used, especially in outpatient practice for induced abortion and for bronchial studies. The drug is administered intravenously at a rate of 8-10 mg/kg at a rate of 30-50 mg/s, i.e. 500 mg of the drug is administered over 15-30 s. This dose causes a narcotic sleep lasting 4-6 minutes. To prolong anesthesia, half the initial dose is administered.

Nurse anesthetist before anesthesia prepares equipment, instruments and pharmacological agents necessary for anesthesia. The equipment is installed in such a way that it does not interfere with the surgeon’s work, and the anesthesiologist can easily monitor the patient’s condition and control devices. Instruments and pharmacological agents are laid out on the anesthesia table.

On it are placed syringes with solutions of non-inhalation drugs (thiopental sodium, etc.), muscle relaxants (ditylin, tubarin), first aid supplies (adrenaline, norepinephrine, prednisolone, mezaton, etimizol, etc.), instruments (laryngoscope, intubation forceps, intubation tubes with curved connectors, guides for endotracheal tubes, a mouth dilator, a special adapter), a bandage for pharyngeal tamponade, moistened with furatsilin solution and wrung out.

After preparing and checking the equipment, instruments and solutions necessary for anesthesia, the patient is taken to the operating room, and the anesthesiologist installs a system for intravenous infusions, puncturing the vein of the upper limb or catheterizing the vein with a plastic catheter.

Induction anesthesia. In maxillofacial surgery, the methods of inducing anesthesia in some cases are determined by the methods of tracheal intubation. If it is intended to carry out intubation by visual methods (through the mouth or nose using a laryngoscope), then anesthesia is administered with intravenous drugs, most often short-acting barbiturates (thiopental sodium, hexenal), less often - Viadryl, heminevrin, ketamine.

In those cases where so-called “blind” intubation is assumed and the anesthesiologist does not know how to carry it out using muscle relaxants, induction of anesthesia should be carried out with inhaled drugs (preferably fluorotane) through a mask.

When administering anesthesia with short-acting barbiturates, a freshly prepared 1 - 2% solution of sodium thiopental or hexenal is usually used. Before introducing a barbiturate solution into a vein, it is necessary to give oxygen to the patient through the mask of the anesthesia machine for 5 - 7 minutes. Then the barbiturate solution is slowly injected into a vein until narcotic sleep occurs. After the patient has fallen asleep, a 2% solution of dithiline or listenone, muscle relaxin is injected into the same vein and intubation is performed.

In children, for induction of anesthesia, you can use nitrous oxide with oxygen in a ratio of 4:1 or 3:1 using a mask. After the child falls asleep, the ulnar vein is punctured and a 1% solution of sodium thiopental or hexenal (no more than 3 mg/kg) is injected into it, and then a short-acting muscle relaxant.

“Clinical operative maxillofacial surgery”, N.M. Alexandrov

Theories of anesthesia

1). Coagulation theory(Kühn, 1864): Drugs cause the coagulation of intracellular proteins in neurons, which leads to disruption of their function.

2). Lipid theory(Hermann, 1866, Meyer, 1899): most narcotic substances are lipotropic, as a result of which they block the membranes of neurons, disrupting their metabolism.

3). Surface tension theory(adsorption theory, Traube, 1904): the anesthetic reduces the force of surface tension at the level of neuronal membranes.

4). Redox theory(Verworn, 1912): narcotic substances inhibit redox processes in neurons.

5). Hypoxic theory(1920): anesthetics cause hypoxia of the central nervous system.

6). Theory of water microcrystals(Pauling, 1961): Drugs in aqueous solution form microcrystals that prevent the formation and propagation of action potentials along nerve fibers.

7). Membrane theory(Hober, 1907, Winterstein, 1916): Drugs cause disruption of the transport of ions across the neuronal membrane, thereby blocking the occurrence of an action potential.

None of the proposed theories fully explains the mechanism of anesthesia.

Modern representations : Currently, most scientists, based on the teachings of N.E. Vvedensky, A.A. Ukhtomsky and I.P. Pavlov, they believe that anesthesia is a kind of functional inhibition of the central nervous system ( physiological theory of central nervous system inhibition- V.S.Galkin). According to P.A. Anokhin, the reticular formation of the brain is most sensitive to the effects of narcotic substances, which leads to a decrease in its ascending influence on the cerebral cortex.

Classification of anesthesia

1). According to factors affecting the central nervous system:

Pharmacodynamic anesthesia- the effect of narcotic substances.
Electronarcosis- action of the electric field.
Hypnonarcosis- the effect of hypnosis.

2). According to the method of introducing the drug into the body:

Inhalation:

Mask.

Endotracheal (ETN).

Endobronchial.

Non-inhalation:

Intravenous.

Intramuscular (rarely used).

Rectal (usually only in children).

3). By quantity of narcotic drugs:

Mononarcosis- 1 drug is used.
Mixed anesthesia- several drugs are used at the same time.
Combined anesthesia- use of various narcotic substances at different stages of the operation; or a combination of drugs with drugs that selectively act on other body functions (muscle relaxants, ganglion blockers, analgesics, etc.).

4). Depending on the stage of the operation:

Introductory anesthesia- short-term, occurs without an excitation phase. Used for rapid induction of anesthesia.
Maintenance anesthesia- used throughout the entire operation.
Basic anesthesia- this is like the background against which the main anesthesia is carried out. The effect of basic anesthesia begins shortly before the operation and lasts for some time after its completion.
Additional anesthesia- against the background of maintenance anesthesia, other drugs are administered to reduce the dose of the main anesthetic.

Inhalation anesthesia

Preparations for inhalation anesthesia

1). Liquid anesthetics- when they evaporate, they have a narcotic effect:

Ftorotan (narcotan, halothane) - used in most domestic devices.
Enflurane (ethrane), methoxyflurane (ingalan, pentrane) are used less frequently.
Isoflurane, sevoflurane, desflurane are new modern anesthetics (used abroad).

Modern anesthetics have a strong narcotic, antisecretory, bronchodilator, ganglion-blocking and muscle relaxant effect, rapid induction of anesthesia with a short excitation phase and rapid awakening. They do not irritate the mucous membranes of the respiratory tract.

Side effects fluorotane: possibility of depression of the respiratory system, drop in blood pressure, bradycardia, hepatotoxicity, increases the sensitivity of the myocardium to adrenaline (therefore, these drugs should not be used during fluorotane anesthesia).

Ether, chloroform and trichlorethylene are not currently used.

2). Gaseous anesthetics:

The most common is nitrous oxide, because it causes rapid induction of anesthesia with virtually no arousal phase and rapid awakening. Used only in combination with oxygen: 1:1, 2:1, 3:1 and 4:1. It is impossible to reduce the oxygen content in the mixture below 20% due to the development of severe hypoxia.

Disadvantage is that it causes superficial anesthesia, weakly inhibits reflexes and causes insufficient muscle relaxation. Therefore, it is used only for short-term operations that do not penetrate the body cavities, and also as induction anesthesia for major operations. It is possible to use nitrous oxide for maintenance anesthesia (in combination with other drugs).

Cyclopropane is currently practically not used due to the possibility of respiratory and cardiac depression.

The principle of anesthesia machines

Any anesthesia machine contains the main components:

1). Dosimeter - used for precise dosing of narcotic substances. Rotary dosimeters of the float type are most often used (the displacement of the float indicates the gas flow in liters per minute).

2). Vaporizer - serves to convert liquid narcotic substances into vapor and is a container into which the anesthetic is poured.

3). Cylinders for gaseous substances- oxygen (blue cylinders), nitrous oxide (gray cylinders), etc.

4). Breathing block- consists of several parts:

Breathing bag- used for manual ventilation, as well as as a reservoir for the accumulation of excess narcotic substances.
Adsorber- serves to absorb excess carbon dioxide from exhaled air. Requires replacement every 40-60 minutes of operation.
Valves- serve for one-way movement of the narcotic substance: inhalation valve, exhalation valve, safety valve (for discharging excess narcotic substances into the external environment) and non-reversible valve (for separating the flows of inhaled and exhaled narcotic substances)
At least 8-10 liters of air should be supplied to the patient per minute (of which at least 20% is oxygen).

Depending on the principle of operation of the breathing unit, there are 4 breathing circuits:

1). Open circuit:

Inhalation - from atmospheric air through the evaporator.

Exhale into the external environment.

2). Semi-open circuit:

Inhale - from the apparatus.

Exhale into the external environment.

Disadvantages of open and semi-open circuits are air pollution in the operating room and high consumption of narcotic substances.

3). Semi-closed circuit:

Inhale - from the apparatus.

Exhale - partly into the external environment, partly back into the apparatus.

4). Closed circuit:

Inhale - from the apparatus.

Exhale into the apparatus.

When using semi-closed and closed circuits, the air, passing through the adsorber, is freed from excess carbon dioxide and again enters the patient. The only one disadvantage of these two circuits is the possibility of developing hypercapnia due to failure of the adsorber. Its performance must be regularly monitored (a sign of its operation is some heating, since the process of absorption of carbon dioxide occurs with the release of heat).

Currently in use anesthesia machines Polynarcon-2, -4 and -5, which provide the ability to breathe along any of the 4 circuits. Modern anesthesia rooms are combined with ventilators (RO-5, RO-6, PHASE-5). They allow you to adjust:

Tidal and minute volume of the lungs.
The concentration of gases in inhaled and exhaled air.
The ratio of inhalation and exhalation time.
Outlet pressure.

The most popular imported devices are Omega, Draeger and others.

Stages of anesthesia(Gwedel, 1920):

1). Analgesia stage(lasts 3-8 minutes): gradual depression of consciousness, sharp decrease in pain sensitivity; however, catch reflexes, as well as temperature and tactile sensitivity are preserved. Respiration and hemodynamic parameters (pulse, blood pressure) are normal.

In the stage of analgesia, 3 phases are distinguished (Artusio, 1954):

Initial phase- no analgesia or amnesia yet.
Phase of complete analgesia and partial amnesia.
Phase of complete analgesia and complete amnesia.

2). Excitation stage(lasts 1-5 minutes): it was especially pronounced during the use of ether anesthesia. Immediately after loss of consciousness, motor and speech excitation begins, which is associated with excitation of the subcortex. Breathing quickens, blood pressure rises slightly, and tachycardia develops.

3). Narcotic sleep stage (surgical stage):

It has 4 levels:

I - U level of eyeball movement: the eyeballs make smooth movements. The pupils are constricted, the reaction to light is preserved. Reflexes and muscle tone are preserved. Hemodynamic parameters and breathing are normal.

II - Level of absence of corneal reflex: eyeballs are motionless. The pupils are constricted, the reaction to light is preserved. Reflexes (including corneal) are absent. Muscle tone begins to decrease. Breathing is slow. Hemodynamic parameters are normal.

III - Pupil dilation level: pupils are dilated, their reaction to light is weak. A sharp decrease in muscle tone, the root of the tongue can sink and block the airways. The pulse increases, the pressure decreases. Shortness of breath up to 30 per minute (diaphragmatic breathing begins to predominate over costal breathing, exhalation is longer than inhalation).

IV - Diaphragmatic breathing level: pupils are dilated, there is no reaction to light. The pulse is frequent, thread-like, the pressure is sharply reduced. Breathing is shallow, arrhythmic, completely diaphragmatic. Subsequently, paralysis of the respiratory and vasomotor centers of the brain occurs. Thus, the fourth level is a sign of a drug overdose and often leads to death.

Depth of anesthesia when using inhalation mononarcosis, it should not exceed the I-II level of the surgical stage; only for a short time it can be deepened to level III. When using combined anesthesia, its depth usually does not exceed 1 level of the surgical stage. It is proposed to operate during the anesthesia stage (rausch anesthesia): short-term superficial interventions can be performed, and when using muscle relaxants, almost any operation can be performed.

4). Awakening stage(lasts from several minutes to several hours, depending on the dose received and the patient’s condition): occurs after stopping the supply of the narcotic substance and is characterized by the gradual restoration of consciousness of other body functions in reverse order.

This classification is rarely used for intravenous anesthesia because the surgical stage is reached very quickly and premedication with narcotic analgesics or atropine can significantly alter pupillary response.

Mask anesthesia

Mask anesthesia is used:

For short operations.
If it is impossible to perform tracheal intubation (anatomical features of the patient, trauma).
When injected into anesthesia.
Before tracheal intubation.

Technique:

1). The patient's head is tilted back (this is necessary to ensure greater patency of the upper respiratory tract).

2). Apply the mask so that it covers the mouth and nose. The anesthesiologist must maintain the mask throughout the anesthesia.

3). The patient is allowed to take a few breaths through a mask, then pure oxygen is connected, and only after that the drug is given (gradually increasing the dose).

4). After anesthesia enters the surgical stage (level 1-2), the dose of the drug is no longer increased and is kept at an individual level for each person. When deepening anesthesia to the 3rd level of the surgical stage, the anesthesiologist must bring the patient’s lower jaw forward and hold it in this position (to prevent tongue retraction).

Endotracheal anesthesia

It is used more often than others, mainly during long-term abdominal operations, as well as during operations on the neck organs. Intubation anesthesia was first used experimentally by N.I. Pirogov in 1847, during operations - by K.A. Rauchfuss in 1890

The advantages of ETN over others are:

Precise dosing of narcotic substances.
Reliable patency of the upper respiratory tract.
Aspiration is virtually eliminated.

Tracheal intubation technique:

The prerequisites for starting intubation are: lack of consciousness, sufficient muscle relaxation.

1). Maximum extension of the patient's head is performed. The lower jaw is brought forward.

2). A laryngoscope (with a straight or curved blade) is inserted into the patient's mouth, on the side of the tongue, and is used to lift the epiglottis. An examination is carried out: if the vocal cords move, then intubation cannot be performed, because you can hurt them.

3). Under the control of a laryngoscope, an endotracheal tube of the required diameter is inserted into the larynx and then into the trachea (for adults, usually No. 7-12) and fixed there by dosed inflation of a special cuff included in the tube. Too much inflation of the cuff can lead to bedsores of the tracheal wall, and too little inflation will break the seal.

4). After this, it is necessary to listen to breathing over both lungs using a phonendoscope. If intubation is too deep, the tube may enter the thicker right bronchus. In this case, breathing on the left will be weakened. If the tube rests on the bifurcation of the trachea, there will be no breathing sounds anywhere. If the tube gets into the stomach, in the absence of respiratory sounds, the epigastrium begins to swell.

Recently, it is increasingly used laryngeal mask. This is a special tube with a device for supplying the respiratory mixture to the entrance to the larynx. Its main advantage is ease of use.

Endobronchial anesthesia

used in lung surgeries when only one lung needs to be ventilated; or both lungs, but in different modes. Intubation of both one and both main bronchi is used.

Indications :

1). Absolute (anesthetic):

Threat of respiratory tract infection from bronchiectasis, lung abscesses or empyema.
Gas leak. It can occur when a bronchus ruptures.

2). Relative (surgical): improvement of surgical access to the lung, esophagus, anterior surface of the spine and large vessels.

Collapsed lung on the surgical side, it improves surgical access, reduces trauma to the lung tissue, allows the surgeon to work on the bronchi without air leakage, and limits the spread of infection with blood and sputum to the opposite lung.

For endobronchial anesthesia the following are used:

Endobronchial obturators
Double-lumen tubes (right-sided and left-sided).

Expansion of a collapsed lung after surgery:

The bronchi of the collapsed lung should be cleared of sputum by the end of the operation. Even with an open pleural cavity at the end of the operation, it is necessary to inflate the collapsed lung using manual ventilation under visual control. Physiotherapy and oxygen therapy are prescribed for the postoperative period.

The concept of adequacy of anesthesia

The main criteria for the adequacy of anesthesia are:

Complete loss of consciousness.
The skin is dry and of normal color.
Stable hemodynamics (pulse and pressure).
Diuresis is not lower than 30-50 ml/hour.
Absence of pathological changes on the ECG (if monitoring is carried out).
Normal volume indicators of pulmonary ventilation (determined using an anesthesia machine).
Normal levels of oxygen and carbon dioxide in the blood (determined using a pulse oximeter, which is placed on the patient’s finger).

Premedication

This is the administration of medications before surgery in order to reduce the likelihood of intraoperative and postoperative complications.

Objectives of premedication:

1). Reduced emotional arousal and feelings of fear before surgery. Hypnotics (phenobarbital) and tranquilizers (diazepan, phenazepam) are used.

2). Stabilization of the autonomic nervous system. Neuroleptics are used (aminazine, droperidol).

3). Prevention of allergic reactions. Antihistamines are used (diphenhydramine, suprastin, pipolfen).

4). Decreased secretion of glands. Anticholinergics (atropine, metacin) are used.

5). Strengthening the effect of anesthetics. Narcotic analgesics (promedol, omnopon, fentanyl) are used.

Many premedication regimens have been proposed.

Scheme of premedication before emergency surgery:

Promedol 2% - 1 ml IM.
Atropine - 0.01 mg/kg s.c.
Diphenhydramine 1% - 1-2 ml IM or (according to indications) droperidol.

Scheme of premedication before planned surgery:

1). The night before bed, take a sleeping pill (phenobarbital) or a tranquilizer (phenazepam).

2). In the morning, 2-3 hours before surgery - an antipsychotic (droperidol) and a tranquilizer (phenazepam).

3). 30 minutes before surgery:

Promedol 2% - 1 ml IM.
Atropine - 0.01 mg/kg s.c.
Diphenhydramine 1% - 1-2 ml IM.

Intravenous anesthesia

This is anesthesia caused by intravenous administration of narcotic drugs.

Main advantages intravenous anesthesia are:

1). Quick induction of anesthesia, pleasant for the patient, with virtually no stage of excitement.

2). Technical ease of implementation.

3). Possibility of strict accounting of narcotic substances.

4). Reliability.

However, the method is not without shortcomings:

1). Lasts for a short time (usually 10-20 minutes).

2). Does not allow complete muscle relaxation.

3). There is a greater risk of overdose compared to inhalation anesthesia.

Therefore, intravenous anesthesia is rarely used independently (in the form of mononarcosis).

The mechanism of action of almost all drugs for intravenous anesthesia is to turn off consciousness and deep inhibition of the central nervous system, while suppression of sensitivity occurs secondary. An exception is ketamine, the effect of which is characterized by sufficient pain relief with partially or completely preserved consciousness.

The main drugs used for intravenous anesthesia

1). Barbiturates:

Sodium thiopental is the main drug.
Hexenal, thiaminal - are used less frequently.

Are used for introductory anesthesia and for short-term anesthesia during minor operations. The mechanism of action is explained by the inhibitory effect on the reticular formation of the brain.

The solution is prepared before surgery: 1 bottle (1 gram) is dissolved in 100 ml of saline (a 1% solution is obtained) and administered intravenously at a rate of approximately 5 ml per minute. 1-2 minutes after the start of administration, unexpressed speech excitation usually occurs (disinhibition of subcortical structures). Motor agitation is not typical. After another 1 minute, consciousness completely turns off and the patient enters the surgical stage of anesthesia, which lasts 10-15 minutes. A longer duration of anesthesia is achieved by fractional administration of 0.1-0.2 g of the drug (i.e. 10-20 ml of solution). The total dose of the drug is no more than 1 g.

Possible side effects: respiratory and cardiac depression, drop in blood pressure. Barbiturates are contraindicated in acute liver failure.

2). Ketamine (ketalar, calypsol).

Used for short-term anesthesia, as well as as a component in combined anesthesia (in the maintenance phase of anesthesia) and in ataralgesia (together with tranquilizers).

Mechanism of action This drug is based on the temporary disconnection of nerve connections between different parts of the brain. Has low toxicity. It can be administered either intravenously or intramuscularly. The general dose is 1-2 mg/kg (intravenous) or 10 mg/kg (intramuscular).

Analgesia occurs 1-2 minutes after administration, but consciousness is preserved and you can talk with the patient. After the operation, the patient does not remember anything due to the development of retrograde amnesia.

This is the only anesthetic that stimulates the cardiovascular system, therefore it can be used in patients with heart failure and hypovolemia; Contraindicated in patients with hypertension.

Possible side effects: increased blood pressure, tachycardia, increased sensitivity of the heart to catecholamines, nausea and vomiting. Frightening hallucinations are characteristic (especially upon awakening). To prevent them, tranquilizers are administered in the preoperative period.

Ketamine is contraindicated in cases of increased ICP, hypertension, angina pectoris, and glaucoma.

3). Deprivan (propofol). Ampoules 20 ml 1% solution.

One of the most modern drugs. It has a short action and therefore usually requires combination with other drugs. It is the drug of choice for introductory anesthesia, but can also be used for long-term anesthesia. A single dose is 2-2.5 mg/kg; after administration, anesthesia lasts 5-7 minutes.

Possible side effects are very rare: short-term apnea (up to 20 seconds), bradycardia, allergic reactions.

4). Sodium hydroxybutyrate(GHB - gamma-hydroxybutyric acid).

Used for induction of anesthesia. The drug has low toxicity, therefore it is the drug of choice for weakened and elderly patients. In addition, GHB also has an antihypoxic effect on the brain. The drug must be administered very slowly. The general dose is 100-150 mg/kg.

Its only disadvantage is that it does not cause complete analgesia and muscle relaxation, which forces it to be combined with other drugs.

5).Etomidate - is used mainly for induction of anesthesia and for short-term anesthesia. A single dose (it lasts for 5 minutes) is 0.2-0.3 mg/kg (can be re-administered no more than 2 times). The advantage of this drug is that it does not affect the cardiovascular system.

Side effects: Nausea and vomiting in 30% of adults and involuntary movements immediately after administration of the drug.

6). Propanidid (epontol, sombrevin).

It is used mainly for induction of anesthesia, as well as for short-term operations. Anesthesia occurs “at the end of the needle”, awakening is very fast (after 5 minutes).

7). Viadryl (predion).

Used in combination with nitrous oxide for induction of anesthesia, as well as during endoscopic examinations.

Propanidid and Viadryl have practically not been used in the last few years.

Muscle relaxants

There are 2 groups of muscle relaxants:

1). Antidepolarizing(long-acting - 40-60 minutes): diplacin, anatruxonium, dioxonium, arduan. The mechanism of their action is the blockade of cholinergic receptors, as a result of which depolarization does not occur and the muscles do not contract. The antagonist of these drugs is cholinesterase inhibitors (prozerin), because Cholinesterase stops destroying acetylcholine, which accumulates in the amount necessary to overcome the blockade.

2). Depolarizing(short-acting - 5-7 minutes): ditilin (listenone, myorelaxin). At a dose of 20-30 mg it causes muscle relaxation, at a dose of 40-60 mg it stops breathing.

The mechanism of action is similar to acetylcholine, i.e. they cause long-term persistent depolarization of membranes, preventing repolarization. The antagonist is pseudocholinesterase (found in freshly citrated blood). Prozerin cannot be used, because due to the inhibition of cholinesterase, it enhances the effect of ditilin.

If both groups of muscle relaxants are used simultaneously, then a “double block” is possible - ditilin acquires the properties of drugs of the first group, resulting in prolonged cessation of breathing.

Narcotic analgesics

reduce the excitability of pain receptors, cause euphoria, anti-shock, hypnotic, antiemetic effects, decreased gastrointestinal secretion.

Side effects:

depression of the respiratory center, decreased peristalsis and gastrointestinal secretion, nausea and vomiting. Addiction quickly sets in. To reduce side effects, combine with anticholinergics (atropine, metacin).

Are used for premedication, in the postoperative period, and also as a component of combined anesthesia.

Contraindications: general exhaustion, insufficiency of the respiratory center. It is not used for labor pain relief.

1). Omnopon (Pantopon) - a mixture of opium alkaloids (contains up to 50% morphine).

2). Promedol - compared to morphine and omnopon, has fewer side effects and is therefore the drug of choice for premedication and central analgesia. The analgesic effect lasts 3-4 hours.

3). Fentanyl has a strong but short-term (15-30 minutes) effect, therefore it is the drug of choice for neuroleptanalgesia.

In case of an overdose of narcotic analgesics, naloxone (an opiate antagonist) is used.

Classification of intravenous anesthesia

1). Central analgesia.

2). Neuroleptanalgesia.

3). Ataralgesia.

Central analgesia

Through the administration of narcotic analgesics (promedol, omnopon, fentanyl), pronounced analgesia is achieved, which plays a major role. Narcotic analgesics are usually combined with muscle relaxants and other drugs (deprivan, ketamine).

However, high doses of drugs can lead to respiratory depression, which often requires the use of mechanical ventilation.

Neuroleptanalgesia (NLA)

The method is based on the combined use of:

1). Narcotic analgesics (fentanyl), which provide pain relief.

2). Neuroleptics (droperidol), which suppress autonomic reactions and cause a feeling of indifference in the patient.

A combination drug containing both substances (thalamonal) is also used.

Advantages of the method is the rapid onset of indifference to everything around; reduction of vegetative and metabolic changes caused by the operation.

Most often, NLA is used in combination with local anesthesia, and also as a component of combined anesthesia (fentanyl with droperidol is administered against the background of nitrous oxide anesthesia). In the latter case, the drugs are administered in fractions every 15-20 minutes: fentanyl - for increased heart rate, droperidol - for increased blood pressure.

Ataralgesia

This is a method that uses a combination of drugs from 2 groups:

1). Tranquilizers and sedatives.

2). Narcotic analgesics (promedol, fentanyl).

As a result, a state of ataraxia (“deprivation”) occurs.

Ataralgesia is usually used for minor superficial operations, and also as a component of combined anesthesia. In the latter case, the following drugs are added to the above drugs:

Ketamine - to potentiate the narcotic effect.
Neuroleptics (droperidol) - for neurovegetative protection.
Muscle relaxants - to reduce muscle tone.
Nitrous oxide - to deepen anesthesia.

The concept of combined anesthesia

Combined intubation anesthesia is currently the most reliable, controlled and universal method of anesthesia. Using several drugs allows you to reduce the dose of each of them and thereby reduce the likelihood of complications. Therefore, it is the method of choice for major traumatic operations.

Advantages of combined anesthesia:

Rapid induction of anesthesia with virtually no arousal phase.
Reducing the toxicity of anesthesia.
The addition of muscle relaxants and neuroleptics allows you to operate at the 1st level of the surgical stage of anesthesia, and sometimes even during the analgesia stage. This reduces the dose of the main anesthetic and thereby reduces the risk of anesthesia complications.
Endotracheal administration of the respiratory mixture also has its advantages: rapid management of anesthesia, good airway patency, prevention of aspiration complications, and the possibility of airway sanitation.

Stages of combined anesthesia:

1). Induction anesthesia:

Typically one of the following drugs is used:

Barbiturates (sodium thiopental);
Sodium hydroxybutyrate.
Deprivan.
Propanidide in combination with a narcotic analgesic (fentanyl, promedol) is rarely used.

At the end of induction anesthesia, respiratory depression may occur. In this case, it is necessary to start mechanical ventilation using a mask.

2). Tracheal intubation:

Before intubation, short-acting muscle relaxants (ditylin) are administered intravenously, while mechanical ventilation is continued through a mask for 1-2 minutes with pure oxygen. Then intubation is performed, stopping mechanical ventilation for this time (there is no breathing, so intubation should not take more than 30-40 seconds).

3). Basic (maintenance) anesthesia:

Basic anesthesia is carried out in 2 main ways:

Inhalation anesthetics are used (fluorothane; or nitrous oxide in combination with oxygen).
Neuroleptanalgesia (fentanyl with droperidol) is also used, alone or in combination with nitrous oxide.

Anesthesia is maintained at the 1st-2nd level of the surgical stage. To relax the muscles, the anesthesia is not deepened to level 3, but short-acting (ditilin) or long-acting muscle relaxants (arduan) are administered. However, muscle relaxants cause paresis of all muscles, including respiratory ones, so after their administration they always switch to mechanical ventilation.

To reduce the dose of the main anesthetic, antipsychotics and sodium hydroxybutyrate are additionally used.

4). Recovery from anesthesia:

Towards the end of the operation, the administration of narcotic drugs is gradually stopped. The patient begins to breathe on his own (in this case, the anesthesiologist removes the endotracheal tube) and regains consciousness; all functions are gradually restored. If spontaneous breathing does not recover for a long time (for example, after using long-acting muscle relaxants), then decurarization is carried out with the help of antagonists - cholinesterase inhibitors (prozerin). To stimulate the respiratory and vasomotor centers, analeptics (cordiamin, bemegride, lobeline) are administered.

Monitoring the administration of anesthesia

During anesthesia, the anesthesiologist constantly monitors the following parameters:

1). Blood pressure and pulse rate are measured every 10-15 minutes. It is advisable to monitor the central venous pressure.

2). In people with heart disease, ECG monitoring is performed.

3). They control the parameters of mechanical ventilation (tidal volume, minute volume of breathing, etc.), as well as the partial tension of oxygen and carbon dioxide in the inhaled, exhaled air and in the blood.

4). Monitor indicators of acid-base status.

5). Every 15-20 minutes, the anesthesiologist performs auscultation of the lungs (to monitor the position of the endotracheal tube), and also checks the patency of the tube with a special catheter. If the tightness of the tube to the trachea is broken (as a result of relaxation of the tracheal muscles), it is necessary to pump air into the cuff.

The anesthesiological nurse keeps an anesthesia card, which notes all the listed parameters, as well as narcotic drugs and their doses (taking into account the stage of anesthesia they were administered). The anesthesia card is included in the patient's medical history.

After the onset of sleep, a 1% (10-15 ml) or 2% (5-8 ml) dithiline solution is injected into the same vein and intubation is performed. As I. N. Mukovozov points out, it is better to use the ulnar vein for administering various solutions and blood transfusions, since thrombophlebitis quite often occurs during venesection of the great saphenous vein on the lower limb in the postoperative period.

It is better to administer medications and transfuse blood into a vein of the upper limb on the side opposite the main operation, as this is less embarrassing for the surgeon. If the veins are poorly expressed, or there are scars in the area of the elbow, it is necessary to perform venipuncture on the other arm, even if this is less convenient for the surgeon, or venesection of the great saphenous vein in the area of the inner ankle (incision 1.5-2 cm anterior to the inner ankle). ankles).

In connection with the injection of a solution of thiopental or hexenal into a vein, some patients experience a decrease in the depth of breathing and frequency of respiratory movements and, very rarely, laryngeal spasm and breath holding (A. A. Volikov, I. N. Mukovozov, 1959, etc.).

The method of rectal anesthesia in young children is as follows: in the morning the child is not fed; 30 minutes after the cleansing enema. Before surgery, a 5% solution of thiopental is injected into the rectum (in the ward) at the rate of 0.5 ml per 1 kg of weight.

After 8-10 minutes. The child goes into a drowsy state, and after 15-20 minutes. he falls asleep. In a sleepy state, the child is taken to the operating room, where, if necessary, 2-3 ml of 1% thiopental solution is additionally injected into the vein. Once sufficiently deep sleep has occurred, a short-acting relaxant is administered intravenously and intubation is performed.

For induction of anesthesia in children, inhalation of nitrous oxide with oxygen (in a ratio of 4:1 and 3:1) is often used using a mask.

For a sleeping child, venipuncture of the ulnar vein is performed and a 1% solution of thiopental or hexenal (at a rate of no more than 3 mg/kg) is first injected into it, and then a short-acting relaxant is injected.

If it is not possible to puncture the vein, the relaxant is injected intramuscularly into the chin area or intralingually; in this case, muscle relaxation and breathing off occur in almost the same time as after intravenous administration.

"Fundamentals of surgical dentistry",
Yu.I. Bernadsky

Anesthesiology and resuscitation: lecture notes Marina Aleksandrovna Kolesnikova

5. Stages of anesthesia

There are three stages of anesthesia.

1. Introduction to anesthesia. Induction of anesthesia can be carried out with any narcotic substance, against the background of which a fairly deep anesthetic sleep occurs without a stage of excitement. They mainly use barbiturates, fentanyl in combination with sombrevin, and promolol with sombrevin. Sodium thiopental is also often used. The drugs are used in the form of a 1% solution and administered intravenously at a dose of 400–500 mg. During induction of anesthesia, muscle relaxants are administered and tracheal intubation is performed.

2. Maintaining anesthesia. To maintain general anesthesia, you can use any narcotic that can protect the body from surgical trauma (fluorotane, cyclopropane, nitrous oxide with oxygen), as well as neuroleptanalgesia. Anesthesia is maintained at the first and second levels of the surgical stage, and to eliminate muscle tension, muscle relaxants are administered, which cause myoplegia of all groups of skeletal muscles, including respiratory ones. Therefore, the main condition of the modern combined method of pain relief is mechanical ventilation, which is carried out by rhythmically compressing the bag or fur or using an artificial respiration apparatus.

Recently, neuroleptanalgesia has become most widespread. With this method, nitrous oxide with oxygen, fentanyl, droperidol, and muscle relaxants are used for anesthesia.

Intravenous induction anesthesia. Anesthesia is maintained by inhalation of nitrous oxide with oxygen in a ratio of 2: 1, fractional intravenous administration of fentanyl and droperidol, 1–2 ml every 15–20 minutes. If the pulse increases, fentanyl is administered, and if blood pressure increases, droperidol is administered. This type of anesthesia is safer for the patient. Fentanyl enhances pain relief, droperidol suppresses autonomic reactions.

3. Recovery from anesthesia. Towards the end of the operation, the anesthesiologist gradually stops administering narcotics and muscle relaxants. The patient regains consciousness, spontaneous breathing and muscle tone are restored. The criterion for assessing the adequacy of spontaneous breathing is the indicators PO 2, PCO 2, pH. After awakening, restoration of spontaneous breathing and skeletal muscle tone, the anesthesiologist can extubate the patient and transport him for further observation to the recovery room.

From the book Anesthesiology and Resuscitation author

From the book Anesthesiology and Reanimatology author Marina Aleksandrovna Kolesnikova

author Marina Aleksandrovna Kolesnikova

From the book Anesthesiology and Resuscitation: Lecture Notes author Marina Aleksandrovna Kolesnikova

Induction of anesthesia and intubation (After sleep onset). Fundamentals of Anesthesiology

Theories of anesthesia

Classification of anesthesia

Inhalation anesthesia

Preparations for inhalation anesthesia

The principle of anesthesia machines

Mask anesthesia

Endotracheal anesthesia

Endobronchial anesthesia

The concept of adequacy of anesthesia

Premedication

The main drugs used for intravenous anesthesia

Muscle relaxants

2). Promedol - compared to morphine and omnopon, has fewer side effects and is therefore the drug of choice for premedication and central analgesia. The analgesic effect lasts 3-4 hours.

3). Fentanyl has a strong but short-term (15-30 minutes) effect, therefore it is the drug of choice for neuroleptanalgesia.

Classification of intravenous anesthesia

Central analgesia

Neuroleptanalgesia (NLA)

Ataralgesia

The concept of combined anesthesia

Monitoring the administration of anesthesia

5. Stages of anesthesia

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