Fundamentals of anesthesiology.

Modern surgery is unthinkable without anesthesiology - the science of pain relief. Having emerged at the end of the 19th century, it contributed to the rapid development of surgery and the transition to a qualitatively new level.

Anesthesiology- the science of protecting the body from surgical trauma and its consequences, monitoring and managing vital functions during surgery.

Modern anesthesiology, using advances in neuropharmacology and precision medical technology, allows long-term complex surgical operations to be performed without serious harm to the patient’s body.

Concept of surgical stress and adequacy of anesthesia

Operational stress

A surgical operation for the body is not only pain, but also, to a certain extent, aggression to which the patient’s body is subjected, causing a complex of compensatory and adaptive reactions. During surgery, the patient experiences “operational stress.” Modern methods of pain management include not only the elimination of pain, which is necessary, but also the management of basic body functions during surgery.

The main components of the development of operational stress:

Psycho-emotional agitation;

Reflexes of a non-painful nature;

Blood loss;

Violation of water and electrolyte balance;

Damage to internal organs.

The development scheme of operational stress can be represented as a three-level system (Zilber A.P., 1984; Fig. 7-1).

Rice. 7-1. The mechanism of the body's reaction during operational stress: 1 - anxiety reaction and mobilization of defenses; 2 - disorders at the tissue and cellular levels; 3 - organ disorders

During anesthesia, all these factors must be taken into account. The extent to which this has been done in full is evidenced by the adequacy of anesthesia.

Adequacy of anesthesia

Objective criteria for the adequacy of pain relief are stable hemodynamic parameters, normal levels of concentration in the blood of hormones, biologically active substances, cyclic nucleotides, enzymes, etc.

During surgery, the anesthesiologist, assessing the adequacy of pain relief, must focus primarily on clinical indicators, and also take into account monitoring data.

Clinical criteria for the adequacy of anesthesia:

The skin is dry, of normal color;

Absence of tachycardia and arterial hypertension;

Diuresis is not lower than 30-50 ml/hour. Monitoring data:

Stable hemodynamics (pulse, blood pressure);

Normal level of blood saturation with oxygen and CO 2;

Normal volume indicators of lung ventilation;

No changes in the ECG curve.

The stress norm for surgical aggression has not been determined. Therefore, there are no specific figures indicating whether anesthesia is adequate. Approximately, periodic deviations of these indicators by 20-25% from the norm (initial level) are considered acceptable.

In recent years, a trend has been noted in anesthesiology in which a large number of drugs are administered during surgery in order to completely block all body reactions to surgical trauma. This type of anesthesia is called stress-free anesthesia. However, this approach is not generally accepted.

Main types of pain relief

All methods of anesthesia are divided into general anesthesia (anesthesia) and local anesthesia.

Anesthesia- artificially induced reversible inhibition of the central nervous system, accompanied by loss of consciousness, sensitivity, muscle tone and some types of reflexes.

Local anesthesia- artificially induced reversible elimination of pain sensitivity in a certain part of the human body while maintaining consciousness.

Preparing for anesthesia

Before any operation, the patient must be examined by an anesthesiologist. For emergency operations, an anesthesiologist is invited immediately after a decision is made about the need for surgery. During a planned operation, the anesthesiologist usually examines the patient the day before, and if there are aggravating factors, in advance. It is advisable that-

the preliminary examination and anesthesiological care would be carried out by the same anesthesiologist.

Objectives of the preoperative examination by an anesthesiologist

When examining a patient before surgery, the anesthesiologist has the following tasks:

Assessment of general condition;

Identification of medical history features that influence the conduct of anesthesia;

Evaluation of clinical and laboratory data;

Determination of the risk level of surgery and anesthesia;

Choice of anesthesia method;

Determining the nature of the necessary premedication.

All of these tasks, except the last one, are similar to the tasks facing the attending surgeon in the preoperative period.

Premedication

The meaning of premedication

Premedication is the administration of medications before surgery in order to reduce the likelihood of intra- and postoperative complications. Premedication is necessary to solve several problems:

Decreased emotional arousal;

Neurovegetative stabilization;

Decreased reactions to external stimuli;

Creation of optimal conditions for the action of anesthetics;

Prevention of allergic reactions to agents used in anesthesia;

Decreased secretion of glands.

Basic drugs

The following main groups of pharmacological substances are used for premedication.

1. Hypnotics (barbiturates: phenobarbital; benzodiazepines: nitrazepam, flunitrazepam).

2. Tranquilizers (diazepam,zepine, oxazepam). These drugs have hypnotic, anticonvulsant, hypnotic and amnesic effects, eliminate anxiety and potentiate the effect of general anesthetics, and increase the threshold of pain sensitivity. All this makes them the leading means of premedication.

3. Neuroleptics (haloperidol, droperidol).

4. Antihistamines (diphenhydramine, chloropyramine, clemastine).

5. Narcotic analgesics (trimeperidine, morphine, morphine + narcotine + papaverine + codeine + thebaine) eliminate pain, have sedative and hypnotic effects, and potentiate the effect of anesthetics.

6. Anticholinergic drugs (atropine, methocynium iodide) block vagal reflexes and inhibit gland secretion.

Local anesthesia– a science that studies methods of protecting the body from the effects of surgical trauma by influencing the peripheral structures of the nervous system. In this case, the nerve fibers conducting pain (nociceptive) impulses can be blocked both directly in the area of ​​​​the operation (terminal, infiltration anesthesia), and on the way to the spinal cord - regional anesthesia (conductor, epidural and spinal anesthesia), at the level of the spinal roots brain Intraosseous and intravenous regional anesthesia are currently used extremely rarely. These two methods are similar in their essence and method of execution. They can be used for operations on the limbs. A tourniquet is applied to the limb, and an anesthetic solution is injected either intravenously or into bones with a spongy structure (femoral, humeral or tibial condyles, individual bones of the foot or hand). For intraosseous administration, special needles with a mandrel are used. Blockade of pain impulses can be caused not only by pharmacological substances, but also by physical factors:

• Cold (surface freezing using chloroethyl).
• Electroanalgesia.
• Electroacupuncture.

General anesthesia(synonymous with general anesthesia) is a condition caused by pharmacological agents and characterized by loss of consciousness, suppression of reflex functions and reactions to external stimuli, which allows surgical interventions to be performed without dangerous consequences for the body and with complete amnesia during the operation. The term “general anesthesia” more fully than the term “anesthesia” reflects the essence of the state that must be achieved to safely perform a surgical operation. In this case, the main thing is to eliminate the reaction to painful stimuli, and depression of consciousness is of less importance. In addition, the concept of “general anesthesia” is more comprehensive, since it also includes combined methods.

History of the development of local and general anesthesia

Opened at the beginning of the 19th century. effective methods of surgical anesthesia were preceded by a centuries-old period of ineffective searches for means and methods of eliminating the excruciating feeling of pain that occurs during injuries, operations and diseases.

Real prerequisites for the development of effective methods of pain relief began to take shape at the end of the 18th century. Among the many discoveries of that period was Hickman's study in 1824 of the narcotic effects of nitrous oxide, diethyl ether and carbon dioxide, he wrote: “The destruction of sensitivity is possible through the methodical inhalation of known gases and thus the most dangerous operations can be performed painlessly.”

The development of local anesthesia was prompted by the introduction of the syringe into medical practice (Wood, Pravets, 1845) and the discovery of the local anesthetic properties of cocaine. In 1905, Eingor studied the chemical structure of cocaine and synthesized novocaine. In 1923–1928 A.V. Vishnevsky created an original method of local anesthesia with novocaine, which became widespread in Russia and abroad. After novocaine was synthesized, which is several times less toxic than cocaine, the possibility of using infiltration and conduction anesthesia increased significantly. Rapidly accumulating experience has shown that under local anesthesia it is possible to perform not only small, but also medium-sized and complex operations, including almost all interventions on the abdominal organs.

In the development and promotion of conduction anesthesia, much credit goes to the famous domestic surgeon V.F. Voino-Yasenetsky, who studied the method for many years and presented the main results of his work in 1915 in his doctoral dissertation. In the 20–30s, differences in the approach to anesthesiological support for operations of domestic and foreign surgeons clearly emerged. While local infiltration anesthesia has become the predominant method in our country, surgeons in Western Europe and the USA for medium and large volume operations preferred general anesthesia, for which specially trained medical personnel were involved. These features in the approach to the choice of anesthesia remain to this day. October 16, 1846. On this day, at Massachusetts General Hospital, dentist William P. Morton euthanized a young man undergoing surgery for a submandibular vascular tumor by surgeon John C. Warren with sulfuric ether. During the operation, the patient was unconscious, did not respond to pain, and after the end of the intervention he began to wake up. It was then that Warren uttered his famous phrase: Gentlemen, this is not a trick!

The positive experience of the participation of anesthesiologists in the provision of resuscitation care was so convincing that on August 19, 1969, the Ministry of Health issued order No. 605 “On improving anesthesiology and resuscitation services in the country,” in accordance with which anesthesiology departments were transformed into anesthesiology and resuscitation departments , and anesthesiologists became anesthesiologists-resuscitators.

Types and methods of local and general anesthesia.

Types of local anesthesia:
a) superficial (terminal),
b) infiltration,
c) regional (conductive). stem, plexus, intraosseous, intravenous, intra-arterial, ganglion (zpidural and subarachnoid anesthesia),
d) novocaine blockades.

1. Terminal anesthesia. The simplest method of local anesthesia. At the same time, Dicaine and Pyromecaine are currently used. Intended for certain operations on mucous membranes and for carrying out certain diagnostic procedures, for example in ophthalmology, otorhinolaryngology, and in the study of the gastrointestinal tract. The anesthetic solution is applied to the mucous membranes by lubrication, instillation, and spraying. In recent years, when performing terminal anesthesia, preference is given to less toxic and fairly effective drugs of the amide group, in particular lidocaine, trimecaine, using 5%-10% solutions.

2. Local infiltration anesthesia. The method of infiltration anesthesia, the creeping infiltrate method, using a 0.25% solution of novocaine or trimecaine, has become widespread in surgical practice over the last 60-70 years. This method was developed at the beginning of the 20th century. Its peculiarity is that after anesthesia of the skin and subcutaneous fatty tissue, the anesthetic is injected in large quantities into the corresponding fascial spaces in the area of ​​​​the operation. In this way, a tight infiltrate is formed, which, due to the high hydrostatic pressure in it, spreads over a considerable distance along the interfascial channels, washing the nerves and vessels passing through them. The low concentration of the solution and its removal as it flows into the wound virtually eliminates the risk of intoxication, despite the large volume of the drug.

It should be noted that infiltration anesthesia should be used in purulent surgery extremely carefully (according to strict indications) due to violations of aseptic norms!, and in oncological practice, ablastic norms!

Using low concentrated anesthetic solutions, 0.25%-0.5% solutions of novocaine or lidocaine are used, while during anesthesia it is safe to use up to 200–400 ml of solution (up to 1 g of dry matter).

Tight infiltration method. In order for the anesthetic to access all receptors, it is necessary to infiltrate the tissue, forming a creeping infiltrate along the course of the upcoming incision, thus only the first injection is painful. Layering, when the skin under the influence of an anesthetic becomes like a “lemon peel”, then the drug is injected into the subcutaneous fat, fascia, muscles, etc. It is important to consider that the fascia is an obstacle to the spread of the anesthetic.

3. Conduction anesthesia or (regional). Conduction is called regional, plexus, epidural and spinal anesthesia, achieved by applying local anesthetic to the nerve plexus. Regional anesthesia is technically more difficult than infiltration anesthesia. It requires precise knowledge of the anatomical and topographical location of the nerve conductor and good practical skills. A feature of conduction anesthesia is the gradual onset of its action (as opposed to infiltration), while first of all anesthesia is achieved in the proximal parts, and then in the distal ones, which is due to the peculiarity of the structure of the nerve fibers.

The main anesthetics for conduction anesthesia: novocaine, lidocaine, trimecaine, bupivocaine.

Small volumes and fairly high concentrations are used (for novocaine and lidocaine, trimecaine - 1-2% solutions, for bupivocaine 0.5-0.75%). The maximum single dose for these anesthetics with the addition of adrenaline (1:200,000 and no more, to avoid tissue necrosis) is 1000 mg, without adrenaline - 600. The local anesthetic is usually administered perineurally in areas specific for each nerve trunk. The effectiveness and safety of conduction anesthesia largely depends on the accuracy of compliance with the general rules of its implementation and on knowledge of the location of the nerve trunks. Endoneural injections should be avoided, as this is fraught with the development of severe neuritis, as well as intravascular injection (risk of general toxic reactions).

Combined methods of pain relief play an important role in modern anesthesiology. The most common combinations are:

Regional conduction anesthesia + intravenous sedation therapy.
(Sedation)
Epidural anesthesia + endotrachial anesthesia.

Effect on the central nervous system: Pharmacodynamic anesthesia (the effect is achieved by the action of pharmacological substances).

By method of drug administration:
Inhalation anesthesia– administration of drugs is carried out through the respiratory tract. Depending on the method of gas administration, mask and endotrachial inhalation anesthesia are distinguished. Non-inhalation anesthesia - drugs are administered not through the respiratory tract, but intravenously (in the vast majority of cases) or intramuscularly.

By the number of drugs used:
Mononarcosis– use of one drug.
Mixed anesthesia– simultaneous use of two or more drugs.
Combined anesthesia - the use of various narcotic drugs depending on the need (muscle relaxants, analgesics, ganglion blockers).

For use at different stages of the operation:
Introductory– short-term, without an excitation phase, used to reduce the time of falling asleep and to save narcotic substances.
Supporting (main) applied throughout the entire operation.
Basic– superficial, in which drugs are administered that reduce the consumption of the main product.

Types and methods of general anesthesia

Today there are the following types of general anesthesia.
Inhalation(by inhalation through a face mask), (endotrachial with or without the use of muscle relaxants);
Non-inhalation– intravenous (through an intravenous catheter);
Combined.

General anesthesia should be understood as targeted measures of medication or hardware aimed at preventing or weakening certain general pathophysiological reactions caused by surgical trauma or surgical disease.

Mask or inhalation type of general anesthesia– the most common type of anesthesia. It is achieved by introducing gaseous narcotic substances into the body. Actually, only that method can be called inhalation when the patient inhales the drugs while maintaining spontaneous (independent) breathing. The entry of inhalational anesthetics into the blood and their distribution in tissues depends on the condition of the lungs and the blood circulation in general.

In this case, it is customary to distinguish between two phases: pulmonary and circulatory. Of particular importance is the ability of the anesthetic to dissolve in the blood. The time of induction of anesthesia and the rate of awakening depend on the solubility coefficient. As can be seen from the statistical data, cyclopropane and nitrous oxide have the lowest solubility coefficient, therefore they are absorbed in the blood in minimal quantities and quickly give a narcotic effect, awakening also occurs quickly. Anesthetics with a high solubility coefficient (methoxyflurane, diethyl ether, chloroform, etc.) slowly saturate the body tissues and therefore cause a prolonged induction with an increase in the period of awakening.

Features of the technique of masked general anesthesia and the clinical course are largely determined by the pharmacodynamics of the drugs used. Inhalational anesthetics, depending on their physical state, are divided into two groups - liquid and gaseous. This group includes ether, chloroform, fluorothane, methoxyflurane, ethane, trichlorethylene.

Endotracheal method of general anesthesia. The endotracheal method best meets the requirements of modern multicomponent anesthesia. For the first time, the endotracheal method of anesthesia with ether was used in an experiment in 1847 by N. I. Pirogov. The first laryngoscope to facilitate tracheal intubation and laryngological practice was invented in 1855 by M. Garcia.

Currently, the endotracheal method of anesthesia is the main one in most areas of surgery. The widespread use of endotracheal general anesthesia is associated with its following advantages:

1. Ensuring free patency of the respiratory tract, regardless of the patient’s surgical position, the possibility of systematic aspiration of bronchial mucous secretions and pathological secretions from the respiratory tract, reliable isolation of the patient’s gastrointestinal tract from the respiratory tract, which prevents aspiration during anesthesia and surgery with the development of severe respiratory damage paths with aggressive gastric contents (Mendelssohn syndrome)

2. Optimal conditions for mechanical ventilation, reducing dead space, which ensures adequate gas exchange, oxygen transport and its utilization by the patient’s organs and tissues with stable hemodynamics. 3.

The use of muscle relaxants, which allows the patient to operate under conditions of complete immobilization and superficial anesthesia, which in most cases eliminates the toxic effect of some anesthetics.

The disadvantages of the endotracheal method include its relative complexity.

Muscle relaxants(curare-like substances) are used to relax muscles during anesthesia, which makes it possible to reduce the dose of anesthetic and the depth of anesthesia, for mechanical ventilation, to relieve a convulsive state (hypertonicity), etc. It should be remembered that the administration of muscle relaxants necessarily leads to the cessation of the work of the respiratory muscles and cessation of independent (spontaneous) breathing, which requires mechanical ventilation.

Studies of the physiology of neuromuscular conduction and pharmacology of neuromuscular blockers in the last decade have shown that the effect occurs in two ways (blockade of the end plate of cholinergic receptors due to their binding by muscle relaxants with a depolarizing effect Francois J. et al., 1984), single-phase relaxants (tubocurarine, pancuronium, etc.). The use of biphasic muscle relaxants (persistent antidepolarization of the potential of the cell membranes of the motor nerve occurs, the drug ditilin and listenone, myorelaxin, etc.). The drugs have a long-term effect (up to 30-40 minutes). The antagonist of this group is prozerin.

Non-inhalation (intravenous) methods of general anesthesia. Traditionally, other methods are understood as intravenous (the most common), as well as rectal, intramuscular, and oral. Currently, non-drug electrostimulation methods of anesthesia are successfully used - central electrostimulation anesthesia, electroneedle analgesia (regional), ataralgesia, central analgesia, neuroleptanalgesia. This trend is due to both practical considerations (reducing the toxicity of anesthesia for patients and operating room personnel) and an important theoretical premise - achieving effective and safe general anesthesia for the patient through the combined use of its various components with selective action.

There is reason to assume that in the coming years the listed groups of drugs will be replenished with new drugs.

Among the existing agents, barbiturates most firmly retain their place in practical anesthesiology, the classic representatives are sodium thiopental (pentothal), hexenal (sodium evipan), used for induction and general anesthesia, endoscopic studies. Ultra-short-acting non-barbiturate anesthetic (Propanidide, Sombrevin, used since 1964). Sodium hydroxybuterate (GHB) is used intravenously, intramuscularly, rectally, orally, in monoanesthesia in therapeutic practice.

Drugs used for local and general anesthesia

Drugs used for local anesthesia. The mechanism of action of local anesthetics is as follows: having lipoidotropic, anesthetic molecules are concentrated in the membranes of nerve fibers, while they block the function of sodium channels, preventing the propagation of the action potential. Depending on the chemical structure, local anesthetics are divided into two groups:

• esters of amino acids with amino alcohols (cocaine, dicaine, novocaine).
• amides of the xylidine type (lidocai, trimecaine, pyromecaine).

Drugs used in general anesthesia. Ether (diethyl ether) - belongs to the aliphatic series. It is a colorless, transparent liquid with a boiling point of 35ºС. Under the influence of light and air, it decomposes into toxic aldehydes and peroxides, so it should be stored in a dark glass container, tightly closed. It is highly flammable and its vapors are explosive. The ether has high narcotic and therapeutic activity; at a concentration of 0.2–0.4 g/l, the analgesic stage develops, and at 1.8–2 g/l an overdose occurs. It has a stimulating effect on the sympathetic-adrenal system, reduces cardiac output, increases blood pressure, irritates the mucous membranes and thereby increases the secretion of the salivary glands. Irritates the gastric mucosa, can cause nausea and vomiting in the postoperative period, promotes the development of paresis and at the same time reduces liver function.

Chloroform (trichloromethane) – colorless transparent liquid with a sweetish odor. Boiling point 59–62º C. Under the influence of light and air, it decomposes and halogen-containing acids and phosgene are formed. Store in the same way as ether. Chloroform is 4–5 times stronger than ether, and the breadth of its therapeutic action is small, which makes it possible to quickly overdose. At 1.2–1.5 vol.% general anesthesia occurs, and at 1.6 vol.% cardiac arrest may occur. (due to toxic effects on the myocardium). Increases the tone of the parasympathetic part of the nervous autonomic system, does not irritate the mucous membranes, is not explosive, depresses the vascular and respiratory centers, is hepatotoxic, promotes the formation of necrosis in liver cells. As a result of the toxic effect on the kidneys and liver, chloroform is not widely used in anesthesiological practice.

Ftorotan (halothane, fluotane, narcotan) – a potent halogen-containing anesthetic that is 4–5 times stronger than ether and 50 times stronger than nitrous oxide. It is a clear, colorless liquid with a sweetish odor. Boiling point 50.2º C. Decomposes when exposed to light, stored with a stabilizer. Ftorotan causes a rapid onset of general anesthesia and rapid awakening, is not explosive, does not irritate the mucous membranes, inhibits the secretion of the salivary and bronchial glands, dilates the bronchi, relaxes the striated muscles, does not cause laryngo and bronchospasm. With prolonged anesthesia, it depresses breathing, has a repressive effect on the contractile function of the myocardium, reduces blood pressure, disrupts heart rhythm, inhibits liver and kidney function, and reduces muscle tone. General anesthesia (fluorotane + ether) is called azeotropic, and it is also possible to use fluorotane with nitrous oxide.

Methoxyflurane (pentran, inhalan) – halogen-containing anesthetic – is a colorless, volatile liquid, a mixture (4 vol.%) with air at a temperature of 60º C ignites. At normal room temperature it is not explosive. It has a powerful analgesic effect with minimal toxic effects on the body, stabilizes hemodynamics, does not cause irritation of the mucous membranes, reduces reflex excitability of the larynx, does not reduce blood pressure, and has a vasodilating effect. However, it has a toxic effect on the liver and kidneys.

Etran (enflurane) – fluorinated ether – gives a powerful narcotic effect, stabilizes hemodynamic parameters, does not cause cardiac arrhythmias, does not depress respiration, has a pronounced muscle relaxant effect, and is devoid of hepatotoxic and nephrotoxic properties.

Trichlorethylene (trilene, rotylane) – the narcotic power is 5–10 times higher than that of ether. It decomposes to form a toxic substance (phosgene), so it cannot be used in a semi-closed circuit. It has found application in minor surgical interventions, does not irritate the mucous membranes, inhibits laryngeal reflexes, stimulates the vagus nerve, reduces tidal volume, and in high concentrations causes cardiac arrhythmias.

Nitrous oxide – the least toxic general anesthetic. It is a colorless gas, non-flammable, patients are quickly put under anesthesia and quickly awaken, does not have a toxic effect on parenchymal organs, does not irritate the mucous membranes of the respiratory tract, and does not cause hypersecretion. When anesthesia deepens, there is a danger of hypoxia, thus, monoanesthesia with nitrous oxide is indicated for low-traumatic operations and manipulations.

Cyclopropane (trimethylene) – a colorless flammable gas, has a powerful narcotic effect, 7-10 times stronger than nitrous oxide, and is released from the body through the lungs. It has high narcotic activity, does not irritate the mucous membranes, minimally affects the liver and kidneys, rapid onset of anesthesia and rapid awakening, causes muscle relaxation.

Preparing the patient for local general anesthesia

Tasks: a) assessment of the general condition, b) identification of features of the anamnesis associated with anesthesia, c) assessment of clinical and laboratory data, d) determination of the degree of risk of surgery and anesthesia (choice of anesthesia method), e) determination of the nature of the necessary premedication.

A patient undergoing planned or emergency surgery is subject to examination by an anesthesiologist-resuscitator to determine his physical and mental condition, assess the degree of risk of anesthesia and conduct the necessary pre-anesthesia preparation and psychotherapeutic conversation.

Along with clarifying complaints and medical history, the nurse anesthetist clarifies a number of issues that are of particular importance in connection with the upcoming operation and general anesthesia: the presence of increased bleeding, allergic reactions, dentures, previous operations, pregnancy, etc.

On the eve of the operation, the anesthesiologist and sister anesthetist visit the patient for a conversation and, in order to clarify any controversial issues, explain to the patient what anesthetic assistance should be provided, the risk of this assistance, etc. In the evening before the operation, the patient receives sleeping pills and sedatives, ( phenobarbital, luminal, seduxen tablets, if the patient has pain, painkillers are prescribed).

Premedication. Administration of medications immediately before surgery in order to reduce the incidence of intra and postoperative complications. Premedication is necessary to solve several problems:

• decreased emotional arousal.
• neurovegetative stabilization.
• creating optimal conditions for the action of anesthetics.
• prevention of allergic reactions to agents used in anesthesia.
• decreased secretion of glands.

Basic drugs For premedication, the following groups of pharmacological substances are used:

• Hypnotics (barbiturates: etaminal sodium, phenobarbital, radedorm, nozepam, tozepam).
• Tranquilizers (diazepam, phenazepam). These drugs have hypnotic, anticonvulsant, hypnotic and amnesic effects, eliminate anxiety and potentiate the effect of anesthetics, and increase the threshold of pain sensitivity. All this makes them the leading means of premedication.
• Neuroleptics (aminazine, droperidol).
• Antihistamines (diphenhydramine, suprastin, tavegil).
• Narcotic analgesics (promedol, morphine, omnopon). Eliminate pain, have a sedative and hypnotic effect, potentiate the effect of anesthetics. ∙ Anticholinergic drugs (atropine, metacin). The drugs block vagal reflexes and inhibit gland secretion.

Stages of ether anesthesia

Of the proposed classifications of the clinical course of ether anesthesia, the Guedel classification is the most widely used. In our country, this classification is somewhat modified by I. S. Zhorov (1959), who proposed to distinguish the stage of awakening instead of the agonal stage.

First stage – analgesia – begins from the moment of inhalation of ether vapor and lasts on average 3-8 minutes, after which loss of consciousness occurs. This stage is characterized by a gradual darkening of consciousness: loss of orientation, the patient answers questions incorrectly, speech becomes incoherent, and the state is half-asleep. The skin of the face is hyperemic, the pupils are the original size or slightly dilated, and actively react to light. Breathing and pulse are rapid and uneven, blood pressure is slightly elevated. Tactile and temperature sensitivity and reflexes are preserved, pain sensitivity is weakened, which allows short-term surgical interventions (rausch anesthesia) to be performed at this time.

Second stage – excitement – ​​begins immediately after loss of consciousness and lasts 1-5 minutes, which depends on the individual characteristics of the patient, as well as the qualifications of the anesthesiologist. The clinical picture is characterized by speech and motor agitation. The skin is sharply hyperemic, the eyelids are closed, the pupils are dilated, the reaction to light remains, involuntary swimming movements of the eyeballs are noted. Breathing is rapid, arrhythmic, blood pressure is increased.

Third stage – surgical (stage of “anesthesia sleep”) – occurs 12-20 minutes after the start of general anesthesia, when, as the body is saturated with ether, inhibition deepens in the cerebral cortex and subcortical structures. Clinically, against the background of deep sleep, loss of all types of sensitivity, muscle relaxation, suppression of reflexes, and decreased breathing are noted. The pulse slows down and blood pressure decreases slightly. The pupil dilates, but (a lively reaction to light remains).

Fourth stage – awakening – occurs after turning off the ether and is characterized by the gradual restoration of reflexes, muscle tone, sensitivity, consciousness in the reverse order. Awakening occurs slowly and, depending on the individual characteristics of the patient, the duration and depth of general anesthesia, lasts from several minutes to several hours. The surgical stage has four levels of depth.

Indications and contraindications for local and general anesthesia

An absolute contraindication to conduction and plexus anesthesia is the presence of tissue contamination in the blockade area, severe hypovolemic conditions, and allergic reactions to the anesthetic.

Along with the methods of regional anesthesia noted above, anesthesia of the fracture area and block of intercostal nerves are often used for pain relief. Fractures of large tubular bones (femur, tibia, humerus) are usually accompanied by the formation of hematomas in the fracture area. Introducing 20-30 ml of 1% or 2% novocaine solution into it after 2-3 minutes. leads to a feeling of “numbness” at the site of injury. Intercostal nerve blockade is carried out at the level of the costal angles and along the posterior or axillary lines. A thin needle 3-5 cm long is inserted towards the rib. Once contact with the bone is achieved, the taut skin is released and the needle is moved to the lower edge of the rib. Having reached the latter, the needle is further advanced to a depth of 3-4 mm and after an aspiration test (risk of damage to the intercostal artery and lungs), 3-5 ml of a 0.5-1% anesthetic solution is injected.

There are no absolute contraindications for general anesthesia. When determining indications, the nature and scope of the proposed intervention should be taken into account, both in outpatient practice and in clinical settings, some surgical interventions can be performed under local anesthesia; in the clinic, the method of epidural anesthesia is often used. Relative contraindications include those situations (in the absence of urgency in the operation) when it is necessary to stabilize the patient’s condition: eliminate hypovolemia, anemia, correct electrolyte disturbances, etc.

Local anesthesia is indicated in all cases where there are no contraindications to its administration and when there are contraindications to all types of general anesthesia.

General anesthesia is indicated in the following cases:

• during operations, including short ones, when it is very problematic or impossible to ensure free patency of the airways.
• patients with a so-called full stomach, when there is always the possibility of regurgitation and aspiration.
• most patients undergoing abdominal surgery.
• patients who have undergone intrathoracic interventions accompanied by unilateral or bilateral surgical pneumothorax.
• during surgical interventions in which it is difficult to control the free patency of the airways due to the position on the operating table (Fowler, Trendelenburg, Overholt, etc. position).
• in cases where during the operation there is a need to use muscle relaxants and mechanical ventilation with intermittent positive pressure, since manual ventilation through the mask of the anesthesia machine is difficult and can cause the gas-narcotic mixture to enter the stomach, which in most cases leads to regurgitation and aspiration.
• during surgery on the head, facial skeleton, neck.
• in most operations using microsurgical techniques (especially long-term ones).
• during operations in patients prone to laryngospasm (long-term cystoscopic examinations and manipulations, hemorrhoidectomy, etc.).
• for most operations in pediatric anesthesiology.

Complications of local and general anesthesia

Complications of local anesthesia. There are no completely safe methods of anesthesia, and regional anesthesia is no exception. Many of the complications (especially severe ones observed when performing central blocks) relate to the period of development and introduction of RA into clinical practice. These complications were associated with insufficient technical equipment, insufficient qualifications of anesthesiologists, and the use of toxic anesthetics. However, there is a risk of complications. Let's look at the most significant of them.

Due to the mechanism of action of central segmental blockade, arterial hypotension is its integral and foreseen component. The severity of hypotension is determined by the level of anesthesia and the implementation of a number of preventive measures. The development of hypotension (a decrease in blood pressure by more than 30%) occurs in 9% of those undergoing surgery and under EA conditions. It occurs more often in patients with reduced compensatory capabilities of the cardiovascular system (elderly and senile age, intoxication, initial hypovolemia).

A very dangerous complication of central RA is the development of total spinal block. It occurs most often as a result of unintentional and undetected puncture of the dura mater during EA and the introduction of large doses of local anesthetic into the subarachnoid space. Profound hypotension, loss of consciousness and respiratory arrest require full resuscitation measures. A similar complication caused by a general toxic effect is possible with accidental intravascular administration of a dose of local anesthetic intended for EA.

Postoperative neurological complications (aseptic meningitis, adhesive arachnoiditis, cauda equina syndrome, interspinous ligamentosis) are rare (0.003%). Prevention of these complications is the use of only disposable spinal needles and careful removal of antiseptic from the puncture site. Infectious meningitis and purulent epiduritis are caused by infection of the subarachnoid or epidural space, most often during their catheterization, and require massive antibacterial therapy.

Epidural hematoma. With prolonged motor blockade after EA, it is appropriate to perform computed tomography to exclude epidural hematoma; If it is detected, surgical decompression is necessary.

Cauda equina syndrome associated with injury to the elements of the cauda equina or spinal cord roots during spinal puncture. If paresthesia appears during needle insertion, it is necessary to change its position and ensure their disappearance.

Interspinous ligamentosis associated with traumatic repeated punctures and manifests itself as pain along the spinal column; does not require special treatment and resolves on its own by 5-7 days.

Headache after spinal anesthesia, described by A. Bier, occurs according to various authors with a frequency of 1 to 15%. It occurs more often in young people than in older people, and in women more often than in men. This is not a dangerous, but subjectively extremely unpleasant complication. Headache occurs 6-48 hours (sometimes delayed 3-5 days) after subarachnoid puncture and continues without treatment for 3-7 days. This complication is associated with the slow “leakage” of spinal fluid through the puncture hole in the dura mater, which leads to a decrease in the volume of spinal fluid and a downward displacement of the structures of the central nervous system.

The main factor that influences the development of post-puncture headaches is the size of the puncture needle and the nature of the sharpening. The use of thin, specially sharpened needles minimizes post-puncture headaches.

The main condition for minimizing complications is the highly qualified specialist and strict adherence to all the rules for performing regional anesthesia:

• strict adherence to the surgical principle of atraumaticity during puncture of the subarachnoid and epidural spaces, anesthesia of nerve trunks and plexuses;
• strict adherence to the rules of asepsis and antiseptics;
• use only disposable kits;
• insertion of a spinal needle only through the sheath when performing SA;
• use of local anesthetics with minimal toxicity and in safe concentrations;
• using only official solutions of local anesthetics to avoid contamination of the cerebrospinal fluid and the penetration of preservatives into it;
• strict adherence to the developed protocols for performing RA, taking into account absolute and relative contraindications.

Performing any method of regional anesthesia is permissible only in operating rooms with mandatory monitoring of the patient’s functional state and compliance with all safety rules adopted in modern clinical anesthesiology.

Complications of general anesthesia. When carrying out modern combined anesthesia, complications are extremely rare, mainly in the first 15 minutes of anesthesia (induction period), during the patient’s awakening and in the post-anesthesia period, being in most cases the result of errors by the anesthesiologist. There are respiratory, cardiovascular and neurological complications.

Respiratory complications include apnea, bronchiolospasm, laryngospasm, inadequate restoration of spontaneous breathing, and recurarization. Apnea (breathing arrest) is caused by hyperventilation, reflex irritation of the pharynx, larynx, root of the lung, mesentery, bronchiolospasm, the action of muscle relaxants, overdose of drugs that depress the central nervous system. (morphine, barbiturates, etc.), neurological complications (increased intracranial pressure), etc. Bronchiolospasm (total or partial) can occur in people with chronic pulmonary pathology (tumors, bronchial asthma) and prone to allergic reactions. Laryngospasm develops when secretions accumulate in the larynx, as a result of exposure to concentrated vapors of general inhalational anesthetics, soda lime dust, trauma with a laryngoscope, rough intubation (against the background of superficial anesthesia).

Inadequate restoration of spontaneous breathing is observed after general anesthesia against the background of total myoplegia and is associated with an overdose of muscle relaxants or general anesthetics, hyperventilation, hypokalemia, extensive surgical trauma, and the general serious condition of the patient. Recurarization is stopping breathing after it has completely recovered in the patient. As a rule, this complication appears when the dosage of proserin is insufficient, after the use of anti-depolarizing relaxants.

Cardiovascular complications include arrhythmias, bradycardia, and cardiac arrest. Arrhythmias develop in the presence of hypoxia, hypercapnia, irritation of the trachea with an endotracheal tube, and the administration of certain drugs (adrenaline, cyclopropane). Bradycardia is caused by irritation of the vagus nerve during operations, the introduction of vagotonic substances (proserine - to restore spontaneous breathing). Cardiac arrest can occur with severe irritation of reflexogenic zones, due to massive blood loss, hypoxia, hypercapnia, hyperkalemia.

Neurological complications include tremors upon awakening, hyperthermia, convulsions, muscle pain, regurgitation, and vomiting. Trembling occurs when the temperature in the operating room is low, there is heavy blood loss, or prolonged open-chest or abdominal surgery. Hyperthermia can be observed in the postoperative period due to a rise in the patient’s already elevated temperature, the use of drugs that disrupt normal sweating (atropine); due to an excessive reaction after warming the patient when performing operations under conditions of general hypothermia or with the development of a pyrogenic reaction to intravenous administration of solutions.

Convulsions are a sign of overexcitation of the central nervous system. - may be caused by hyperventilation, hypercapnia, overdose or rapid administration of general anesthetics, observed in diseases of the central nervous system. (brain tumor, epilepsy, meningitis). Muscle pain is observed when depolarizing relaxants (ditilin) ​​are used for myoplegia after short-term general anesthesia. With spontaneous and artificial ventilation, aspiration or injection of fluid into the trachea is possible as a result of regurgitation of the contents of the gastrointestinal tract with intestinal obstruction and heavy gastrointestinal bleeding. Vomiting often develops during inadequate premedication, increased sensitivity of some patients to morphine, or severe tracheal intubation in an inadequately anesthetized patient. There is a category of patients in whom vomiting occurs for no apparent reason.

Features of local and general anesthesia in children

Features of local anesthesia. Local anesthesia is one of the most common procedures in pediatric medical practice, and local anesthetics are among the most commonly used medications. This is a powerful tactical tool in the surgeon’s arsenal, without which most modern treatment protocols are impossible.

The issue of local anesthesia becomes especially acute in children under 4 years of age. To date, we do not have effective and safe local anesthetics for this age group. As clinical experience shows, the need for local anesthesia arises when treating children 4 years of age and younger. In the practice of most doctors working with children, there are many cases where medical intervention requires pain relief. However, the duration and complexity of the intervention does not always justify putting the child under anesthesia. The most optimal solution in this situation remains the use of injection anesthesia, similar to how this is done in older children, but always taking into account the characteristics of early childhood.

Based on their pharmacological properties, the most effective drugs in dentistry today are anesthetics based on articaine and mepivacaine. This has been proven by clinical practice, but their use, as well as proprietary forms containing these anesthetics, is not indicated in children under 4 years of age due to the lack of data on effectiveness and safety. No such studies have been conducted. Therefore, the doctor actually does not have the means to solve the clinical problem assigned to him. However, in real clinical practice, children under 4 years of age, during dental treatment, are given local anesthesia with drugs based on articaine and mepivacaine. Despite the lack of official statistics on this issue, analysis of the frequency and structure of complications during local anesthesia in children under 4 years of age indicates the accumulated positive experience of our and foreign specialists.

There is no doubt that local anesthesia in pediatric surgery is an indispensable procedure. It should also be recognized that the risk of complications with local anesthesia in childhood is higher, but their structure will be different. Our experience and the experience of our colleagues indicates that the most common type of complications are toxic reactions. They belong to the group of predictable complications, therefore, the doctor’s special attention should be paid to the dose of the anesthetic, the time and technique of its administration.

Features of general anesthesia are caused by the anatomical, physiological and psychological characteristics of the child’s body. At the age of up to 3 years, the most gentle methods of induction of anesthesia are indicated, which, like premedication, are carried out for all children under the age of 12 in a familiar environment, usually in a ward. The child is delivered to the operating room already in a state of narcotic sleep.

With A. o. All narcotic substances can be used in children, but it should be remembered that their narcotic range in a child narrows and, consequently, the likelihood of overdose and respiratory depression increases. In childhood, the thermoregulation system is very imperfect, so within 1-2 hours of surgery, even in older children, body temperature can decrease by 2-4°.

Specific complications of A. o. observed in children include convulsions, the development of which may be associated with hypocalcemia, hypoxia, as well as subglottic edema of the larynx. Prevention of these complications consists of ensuring adequate conditions for artificial ventilation of the lungs during surgery, correcting water and electrolyte disturbances, correctly choosing the size of the endotracheal tube (without sealing cuffs) and maintaining the temperature on the operating table using a warming mattress.

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 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.