Narcotics quite quickly and easily cause loss of consciousness and pain sensitivity, but do not sufficiently relax the skeletal muscles. To obtain sufficient muscle relaxation, especially during operations in the abdominal cavity, it is necessary to deepen anesthesia to levels III 2 -III 3, giving the patient a significant amount of drugs.

It is now known that the deeper the anesthesia, the greater the harm done to the body. Therefore, for any operation, the correct anesthesia is considered to be one that is carried out at a superficial level, sufficient to completely turn off the patient’s pain sensitivity and consciousness. Due to the need to reduce the amount of the main drug, there is a need to use substances that provide muscle relaxation. For this purpose, muscle relaxants (curare-like substances) are used in anesthesiology - agents that cause relaxation of skeletal muscles and do not cause any serious complications.

The use of muscle relaxants, which provide ideal relaxation of the striated muscles, makes it possible to operate under superficial anesthesia, which uses minimal amounts of narcotic drugs.

Curare is a plant that has long been known as “arrow poison”. The Indians of South America discovered that an animal wounded by an arrow smeared with curare juice quickly dies, but its meat does not become poisonous. It was later established that the death of these animals occurs from asphyxia due to respiratory arrest.

Currently, clinics use specially prepared and purified curare preparations. The mechanism of action of muscle relaxants is that they temporarily prevent the transfer of excitation from nerve to muscle at the neuromuscular junction, that is, to the neuromuscular junction or to the so-called end plates. They act on the end plates of only the motor nerves, not the sensory nerves, and therefore do not cause loss of pain sensitivity.

The paralyzing (relaxing) effect of relaxants on skeletal muscles spreads in a certain sequence. First, the muscles of the head and neck relax, then the muscles of the limbs and torso relax, and finally the respiratory muscles, intercostal muscles and diaphragm are paralyzed. Breathing stops for a while, but the respiratory center remains intact. The return to normal occurs in reverse order.

In practice, the relaxant is not an analgesic or hypnotic. Without narcotic switching off the patient’s consciousness, relaxants cannot be used.

Currently, in anesthesiology, the boundaries of the use of muscle relaxants are quite clearly defined. They are used: 1) to facilitate tracheal intubation; 2) for the use of artificial ventilation in patients under anesthesia, and 3) for performing superficial anesthesia using a relatively smaller amount of the main anesthetic.

The so-called depolarizing and non-depolarizing muscle relaxants have received the most practical significance. Depolarizing relaxants change the location of potassium and sodium ions in the neuromuscular junction and thereby create persistent depolarization, that is, a change in electrical charge in which the transfer of excitation from nerve to muscle is impossible.

Depolarizing and non-depolarizing relaxants

a) performing pulmonary ventilation when using muscle relaxants

b) complications when using relaxants

1. Providing conditions for tracheal intubation.

2. Providing muscle relaxation during surgical interventions to create optimal working conditions for the surgical team without excessive doses of drugs for general anesthesia, as well as the need for muscle relaxation during some diagnostic procedures performed under general anesthesia (for example, bronchoscopy).

3. Suppression of spontaneous breathing for the purpose of mechanical ventilation.

4. Elimination of convulsive syndrome when anticonvulsants are ineffective.

5. Blockade of protective reactions to cold in the form of muscle tremors and muscle hypertonicity during artificial hypothermia.

6. Myorelaxation during reposition of bone fragments and reduction of dislocations in joints where there are powerful muscle masses.

Characteristics of the main drugs, methods of their use

The only representative of depolarizing muscle relaxants currently used is succinylcholine (ditylin, listenone).

The main qualities that determine its popularity despite numerous side effects are the very rapid onset of action (from 30 to 60 s) and its short duration (less than 10 minutes). The drug is administered at a dose of 1-1.5 mg/kg. It should be noted, however, that if precurarization is used, the intubation dose of succinylcholine increases by 1.5 times.

Succinylcholine is rapidly destroyed by plasma pseudocholinesterase. After a dose of 1 mg/kg, the duration of action is 6-8 minutes. Sometimes it is also used to maintain relaxation, administered as an infusion at a rate of 20 to 110 mcg/kg/min (average 60 mcg/kg/min), especially for short-term manipulations (for example, bronchoscopy) and operations.

Considering the numerousness and severity of side effects, which often negate the positive qualities of succinylcholine, currently the indications for its use are increasingly narrowed. It is believed that it makes sense to use depolarizing relaxants only when difficult intubation is expected (to quickly restore muscle tone and transfer the patient to spontaneous breathing in case of failure - although even this position is controversial, a number of authors believe that in this situation the use of muscle relaxants should be abandoned altogether) or with a high risk of regurgitation and aspiration ("full" stomach), in order to most quickly perform tracheal intubation and transfer the patient to mechanical ventilation. Low qualifications of the anesthesiologist (in terms of tracheal intubation) must be added to the indications for the use of ditilin.

Elimination of the drug is carried out due to its destruction by pseudocholinesterase (butyrylcholinesterase) of the blood plasma into choline and succinyl monocholine, followed by further hydrolysis of the latter into succinic acid and choline.

The metabolism of the drug is impaired by hypothermia (slow hydrolysis) and by low concentrations or a hereditary defect of pseudocholinesterase. Non-depolarizing relaxants exhibit an antagonistic effect on succinylcholine. So even precurarization (as mentioned above) forces you to increase the dose of succinylcholine by 50-100%. The exception here is pancuronium. It enhances the effect of succinylcholine by inhibiting the activity of pseudocholinesterase.

From a fairly large list of non-depolarizing relaxants, we will consider only the most frequently used. And we'll start with an idea of ​​the ideal muscle relaxant.

Properties of the “ideal” muscle relaxant (slide):

high activity;

competitive mechanism of action;

selectivity of action on n-cholinergic receptors of skeletal muscles;

rapid onset of action;

short-term block of neuromuscular transmission (with a single injection no more than 15 minutes);

lack of potentiation or cumulation upon repeated administration;

no side effects;

low toxicity;

lack of physiological and toxic activity of metabolites and their rapid elimination from the body;

presence of effective antagonists;

storage stability;

profitability for industrial production.

Table 4

Modern muscle relaxants (1)

Table 5

Modern muscle relaxants (2)

According to the literature, the most used non-depolarizing muscle relaxants in the world today are atracurium and cisatracurium, doxacurium, mivacurium, vecuronium, and the rapidly gaining popularity of rocuronium. Pancuronium (Pavulon) and pipecuronium (Arduan) are still widely used in our country. In this regard, we will dwell in more detail on the main and side effects of these particular representatives of the class of non-depolarizing relaxants.

COMBINED ANESTHESIA WITH LOCAL ANESTHESIA

MUSCLE RELAXANTS- These are drugs that relax striated muscles. There are relaxants of central and peripheral action. Centrally acting relaxants include tranquilizers, but their muscle relaxant effect is not associated with a peripheral curare-like effect, but with an effect on the central nervous system. Peripheral muscle relaxants, due to the peculiarities of their influence on the process of synaptic transmission, are divided into two groups.

Non-depolarizing muscle relaxants. These include Tracrium, Pavulon, Arduan, Norkuron, Nimbex. They paralyze neuromuscular transmission due to the fact that they reduce the sensitivity of the H-cholinergic receptors of the synaptic region to acetylcholine and thereby eliminate the possibility of depolarization of the end plate and excitation of the muscle fiber. Compounds of this group are true curare-like substances. Pharmacological antagonists of these compounds are anticholinesterase substances (prozerin, galantamine): by inhibiting the activity of cholinesterase, they lead to the accumulation of acetylcholine in the area of ​​synapses, which, with increasing concentration, weakens the interaction of curare-like substances with H-cholinergic receptors and restores neuromuscular transmission.

Depolarizing muscle relaxants cause muscle relaxation, providing a cholinomimetic effect, accompanied by persistent depolarization, which also disrupts the conduction of excitation from the nerve to the muscle. Drugs in this group are quickly hydrolyzed by cholinesterase; anticholinesterase drugs enhance their effect. A representative of this group is succinylcholine (dithiline, listenone).

Depending on the duration of the neuromuscular block caused, muscle relaxants are divided into 3 groups:

A) causing a rapidly developing neuromuscular blockade (within 1 minute), but with a short period of action (up to 15 minutes) - succinylcholine.

C) causing a rapidly developing neuromuscular blockade with an average duration of action (15-30 minutes) - norcuron, tracrium, nimbex.

C) causing neuromuscular blockade with a long period of action (30-150 minutes) - arduan, pavulon.

Muscle relaxants are used only when the patient’s consciousness is turned off!!!

Neuroleptanalgesia- a method of general non-inhalation anesthesia, in which the main pharmacological drugs are a powerful antipsychotic (droperidol) and a strong central analgesic (fentanyl, morphine, promedol).

Ataralgesia– combined use of an ataractic (diazepam) and a strong narcotic analgesic (promedol, fentanyl).

Central analgesia- a method of general anesthesia in which all components of anesthesia are induced by large doses of central analgesics (morphine, fentanyl, promedol, dipidolor).

COMBINED ANESTHESIA– anesthesia, when the patient’s consciousness is turned off by a general anesthetic during the operation, and relaxation in the operation area, peripheral analgesia and blockade of the autonomic nerves are provided by one of the types of local anesthesia.

Stages of anesthesia and control of anesthesia depth

When general anesthetics are introduced into the body, a natural phasing pattern has been established in the clinical picture of general anesthesia, which is most clearly manifested during mask general anesthesia with ether. This diagram of the stages of anesthesia proposed by Guedel in 1937.

First stage– ANALGESIA STAGE – begins from the moment the general anesthetic is administered and continues until loss of consciousness. Characteristic: gradual darkening of consciousness; at first there is a loss of orientation, patients answer questions incorrectly; speech becomes incoherent, 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 slightly increased, blood pressure is increased. Tactile and temperature sensitivity and reflexes are preserved, pain sensitivity is sharply weakened, which allows short-term surgical interventions and manipulations (rausch anesthesia) to be performed at this stage. At this stage, it is proposed to distinguish three phases according to Artusio (1954): the first is the beginning of euthanasia, when complete analgesia and amnesia have not yet occurred, the second is complete analgesia and partial amnesia, the third is the development of complete analgesia and complete amnesia. The duration of the analgesia stage depends on the general condition of the patient, his age, premedication and the general anesthetic used and varies from several seconds (when using non-inhalational anesthetics) to 10 minutes (when using inhalational anesthetics).

Second stage– EXCITATION STAGE – begins immediately after loss of consciousness and continues until the patient relaxes. The clinical picture is characterized by speech and motor agitation. The skin is sharply hyperemic, the eyelids are closed, the pupils are dilated, their reaction to light is preserved, lacrimation and swimming movements of the eyeballs are noted. The muscles are sharply tense (trismus), cough and gag reflexes are strengthened, pulse and breathing are rapid, arrhythmic, blood pressure is increased. Sometimes there is involuntary urination, coughing, vomiting, and heart rhythm disturbances. No surgical interventions are allowed at this stage due to increased muscle tone and reflexes. The duration of this stage depends on the individual characteristics of the patient and the general anesthetic used and can range from a few seconds (when using non-inhalational anesthetics) to 10 minutes (when using inhalational anesthetics).

Third stage– SURGICAL STAGE – occurs when, as the body is saturated with anesthetic, inhibition occurs 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, slowing and deepening of breathing are noted. The pulse slows down and blood pressure decreases slightly. The skin is pale pink and dry. To control the depth of general anesthesia and prevent overdose, four levels are distinguished at this stage.

Level 1 – level of movement of the eyeballs – against the background of restful sleep, muscle tone and laryngeal-pharyngeal reflexes are still preserved. Breathing is smooth, pulse is slightly increased, blood pressure is at the initial level. The eyeballs make slow circular movements, the pupils are evenly constricted, they react quickly to light, the corneal reflex is preserved. Superficial reflexes (skin) disappear.

Level 2 – level of the corneal reflex. The eyeballs are fixed, the corneal reflex disappears, the pupils are constricted, and their reaction to light is preserved. The laryngeal and pharyngeal reflexes are absent, muscle tone is significantly reduced, breathing is even, slow, pulse and blood pressure are at the initial level, the mucous membranes are moist, the skin is pink.

Level 3 – level of pupil dilation. The first signs of an overdose appear - the pupil dilates due to paralysis of the smooth muscles of the iris, the reaction to light is sharply weakened, and dryness of the cornea appears. The skin is pale, muscle tone sharply decreases (only sphincter tone is preserved). Costal breathing gradually weakens, diaphragmatic breathing predominates, inhalation is somewhat shorter than exhalation, pulse quickens, blood pressure decreases.

Level 4 – the level of diaphragmatic breathing is a sign of overdose and a harbinger of death. It is characterized by a sharp dilation of the pupils, their lack of reaction to light, a dull, dry cornea, complete paralysis of the respiratory intercostal muscles; Only diaphragmatic breathing is preserved - shallow, arrhythmic. The skin is pale with a cyanotic tint, the pulse is threadlike and rapid, blood pressure is not determined, sphincter paralysis occurs.

Fourth stage– AGONAL STAGE – paralysis of the respiratory and vasomotor centers, manifested by cessation of breathing and cardiac activity.

During the operation, the depth of general anesthesia should not exceed level 2 of the surgical stage. AWAKENING of the patient occurs after the cessation of the administration of general anesthetic and is characterized by the gradual restoration of reflexes, muscle tone, sensitivity, consciousness in reverse order, reflecting the stages of general anesthesia.

Awakening occurs slowly and depends on the individual characteristics of the patient, the duration and depth of general anesthesia, the general anesthetic and lasts from several minutes to several hours.

Muscle relaxants (muscle relaxants)- These are drugs that relax the skeletal muscles. These include organic compounds - plant alkaloids (true curare), the molecule of which contains two nitrogen atoms (quaternary), and drugs of synthetic origin. Presumably, the concept of “curare” comes from the name of a river flowing in South America, where, in fact, the plants are located. Synthetic and organic compounds have different mechanisms of action, but perform almost the same function.

The use of drugs for this purpose in clinical practice has brought the development of anesthesiology to a completely new level, as it has allowed anesthesiologists around the world to abandon deep anesthesia during operations, which is sometimes very dangerous for the further condition and life of patients.

Muscle relaxants are mainly used in anesthesiology during endotracheal intubation. They prevent reflex activity of voluntary muscles and allow the administration of smaller doses of anesthetics, which, in turn, reduces the risk of complications after anesthesia. Muscle relaxants, causing absolute neuromuscular blockade, reduce the level of pathological impulses from muscles in the central nervous system, thereby helping to provide the patient with effective protection from stress during surgery. When anesthesia is performed without these drugs, a certain muscle tone is maintained, which during surgery can interfere with the surgeon’s actions.

This type of drug began to be widely used in medicine in the 20th century. For the first time, during an operation, in order to achieve complete muscle relaxation, in 1942, D. Johnson and H. Griffiths used one of the muscle relaxants - Intocostrin.

Indications for the use of muscle relaxants

Muscle relaxants indications for use:

1. operations using superficial anesthesia;
2. in order to ensure good muscle relaxation during surgery of any complexity;
3. in order to turn off spontaneous breathing and provide optimal conditions for ventilation and intubation;
4. to prevent muscle spasms during tetanus, rabies, status epilepticus, intractable seizures of various etiologies.

Classification

All muscle relaxants are divided into two categories: depolarizing and non-depolarizing. According to the duration of action, drugs are divided into:

• ultra-short action - the action lasts 5 - 7 minutes;
• short – their duration of action is less than 20 minutes;
• medium – duration of action is less than 40 minutes;
• long-term – duration of action is 40 minutes or more.

Depolarizing muscle relaxants are suxamethonium preparations (ditylin, listenone, succinylcholine). They have an ultra-short action and differ from each other in the amount of salt they contain.

Non-depolarizing muscle relaxants are available in short, medium and long-acting forms. Short-acting - mivacurium. Medium-acting - rocuronium, vecuronium, cisatracurium, atracurium. Long-acting - pancuronium, tubocurarine, pipecuronium.

Side effects of muscle relaxants

Cardiovascular system: fluctuations in heart rate and blood pressure, rhythm disturbances.

Hyperkalemia. If the patient has conditions characterized by elevated potassium levels (tetanus, burns, myopathy, extensive trauma, acute intestinal obstruction), the use of these drugs may pose a threat to his life.

Muscular system: muscle pain after surgery.

Due to the fact that succilcholine increases pressure (intraocular), its use during ophthalmic operations is often limited.

Possible increase in brain current and intracranial pressure (ultra-short-acting muscle relaxants).

Side effects of non-depolarizing muscle relaxants:

1. fluctuations in blood pressure;
2. hyperemia of the skin;
3. bronchospasm;
4. rarely – anaphylactic reactions.

All drugs for this purpose are characterized by common side effects, such as drowsiness, lethargy, dizziness. With long-term use of muscle relaxants of any of the groups, the patient may develop drug dependence and addiction. It is not advisable to use them in relation to persons whose professional activity requires a good mental reaction and precise coordination of movements.

In most cases, muscle relaxants in anesthesiology are administered intravenously into the patient's body. Antidepolarizing muscle relaxants cause gradual relaxation of muscle tissue. As a rule, relaxation of the muscles of the limbs is observed, then the abdominal muscles, intercostal muscles and diaphragm relax. There are no reflex twitches. Visually, this process cannot always be noticed, especially when large doses of the drug are administered.

A positive aspect of using relaxants is the ability to perform complex surgical interventions under superficial anesthesia, which is characterized by a low level of anesthetic in the blood. This eliminates the danger of anesthesia for the health and life of the patient.

Experienced in using muscle relaxants under the influence of only nitrous oxide, they perform the most complex surgical interventions on the abdominal or chest organs of their patients. In some individual cases, doctors add other drugs to enhance the pain-relieving effect of nitrogen.

It is muscle relaxants that enable qualified specialists to perform very complex, lengthy operations on aneurysms, lungs, mediastinal organs, orthopedic operations, surgical interventions on the cardiovascular system without deep anesthesia with serious narcotic drugs. A minimum of anesthetic with maximum oxygen saturation is sufficient. A completely relaxed muscular system of the human body allows surgeons to easily carry out the necessary actions during surgery.

To reduce the toxicity of the general anesthetic, drugs from other groups (neuroleptics, muscle relaxants) are additionally used. Muscle relaxants (curare-like substances) are drugs that independently turn off muscle tension by blocking neuromuscular transmission. Muscle relaxants are used for the following purposes: 1) muscle relaxation during anesthesia, which helps reduce the dose of anesthetic and the depth of anesthesia; 2) as a consequence of the blockade of neuromuscular impulse transmission - the use of mechanical ventilation; 3) to relieve cramps, muscle hypertonicity, etc. The absence or sharp decrease in muscle tone is a mandatory component to provide pain relief during abdominal operations. It should be remembered that the administration of muscle relaxants necessarily leads to the cessation of the respiratory muscles and the cessation of spontaneous breathing, which requires mechanical ventilation. According to the mechanism of action, muscle relaxants are divided into antidepolarizing (pavulon, tubocurarine, diplacin) and depolarizing (ditilin, listenone, myorelaxin), and by duration of action - short (ditilin, listenone) and long-term (pavulon, tubocurarine). After the end of the operation, proserin, which is an anticholinesterase drug, is administered to eliminate the effect of muscle relaxants (decurarization).

35. Neuroleptanalgesia. Aspects of application.

Neuroleptanalgesia (NLA) is a method of intravenous analgesia based on the combined use of the powerful neuroleptic droperidol and the narcotic analgesic fentanyl. The advantage of the method is a unique effect on the central nervous system, characterized by the rapid onset of indifference to the environment, the absence of motor restlessness, and a decrease in the severity of autonomic and metabolic reactions to surgical aggression. NLA usually acts as a component of combined anesthesia or in combination with local anesthesia. Most often, NLA is performed against the background of mechanical ventilation with nitrous oxide. Indications for: long-term severe operations on all parts of the chest and abdominal cavities, especially on the heart, large vessels, as well as neurosurgical interventions of increased trauma; high-risk operations in patients in serious condition, elderly, and with concomitant pathologies; performing special operations that require constant contact between the surgeon and the patient (otology, neurosurgery, etc.). Absolute contraindications to NLA are found only in an obstetrics and gynecology clinic during a cesarean section until the fetus is removed. Relative contraindications to NLA exist in diseases of the extrapyramidal system, bronchial asthma, and drug addicts.

36. Regional methods of anesthesia (definition, classification, indications for use).

Regional anesthesia methods are characterized by achieving an analgesic effect, turning off conduction in a specific nerve or plexus of nerves, while maintaining the patient’s consciousness and breathing. Regional anesthesia class:

Conductor - block. impulse transmission to the level of the nerve trunk or nerve plexus - epidural - block of impulse transmission to the level of the roots of the spinal nerves by introducing an anesthetic into EPIDURAL E space.-spinal - block of impulse transmission to the level of the roots of the spinal nerves by introducing an anesthetic into SUBDURAL space.-plexus - carried out by introducing an anesthetic solution into the area of ​​the nerve plexus.

The generally accepted indications for regional anesthesia are: intraoperative analgesia; postoperative pain relief; treatment of chronic neuropathic pain, as well as pain associated with malignant tumors; carrying out preventive analgesia (the likelihood of postoperative chronic pain syndrome will be much less if epidural anesthesia is started the day before knee replacement, or the likelihood of phantom pain will be less when epidural anesthesia begins before, rather than after, amputation of the affected limb).