Inhalation anesthesia for dogs. Inhalation anesthesia

Inhalation anesthesia- a type of anesthesia in which its effects (sleep, muscle relaxation, analgesia) are achieved by administering an anesthetic through the patient’s lungs. Anesthetic molecules, penetrating the patient’s respiratory system, pass the barrier of the pulmonary capillaries and are transported circulatory system to body tissues, reaching ultimate goal- brain tissue. When the required concentration of the drug is reached in nerve tissue there is a reversible depression of consciousness in the patient, muscle relaxation and sleep required for surgical intervention. Compared to TVA (total intravenous anesthesia, in which an anesthetic is injected into a patient's vein), inhalational anesthesia has comparatively better controllability and a unique route of absorption and elimination (excretion) of the anesthetic. This type of anesthesia has no direct effect on other organ systems, for example, on the excretory system of the kidneys.

How is inhalation anesthesia performed?

Equipment required to perform inhalation anesthesia in the clinic:

oxygen supply system (cylinder, concentrator, oxygen station),
anesthesia-respiratory apparatus,
induction chambers, masks, patency equipment respiratory tract,
directly the anesthetic itself.

There are several ways to deliver the anesthetic mixture to the patient. The doctor may use an induction chamber, a mask, or administer an anesthetic through an endotracheal tube. What are the main differences between the methods?

The induction chamber (induction of anesthesia) is a transparent container into which the patient is placed. The anesthetic is delivered directly into the confined space of the container. Thus, with minimal physical contact, the patient enters a state of anesthesia. The disadvantages of this method of gas supply include the inability to clearly control the depth of anesthesia, perform hardware monitoring (capnography, pulse oximetry, etc.), high consumption of anesthetic and, accordingly, harm to personnel. This type of induction is used in wild and laboratory animals, as well as in overly aggressive patients.

The anesthetic mixture can also be administered using a mask. To do this, the mask must be of the recommended size to prevent leakage of the anesthetic. The main advantages and disadvantages are similar to those of the induction chamber, the only differences being the possible preliminary sedation of the patient (not every animal will allow a mask to be put on) and the need to secure the animal at the time of induction of anesthesia.

Delivery of the drug through the endotracheal tube is the main method used in anesthesiological practice. The anesthetic enters the lungs through a tube made of non-toxic plastic, polyvinyl chloride (PVC). Previous intubation (insertion of a tube) is usually performed under the influence of an intravenous anesthetic short acting. This type of drug supply allows you to maintain airway patency and monitor the composition of gases in the mixture.

How dangerous is gas anesthesia?

The first officially recognized anesthesia was ether anesthesia (1846). The ether had a number of side effects, unwanted effects. In modern anesthesiology, about six inhalational anesthetics are used: nitrous oxide, fluorotane, enflurane, isoflurane, sevoflurane and desflurane. Unlike their predecessors, modern anesthetics are much less toxic. In addition, modern equipment allows the anesthesiologist to control the flow of anesthetic gas at the level necessary for surgical intervention.

In what situations is the use of gas anesthesia justified?

Gas inhalation is a fairly common type of anesthesia in veterinary practice. It is used both in mono mode for short, painless procedures, and in combined/combined anesthesia for long-term interventions. To achieve the optimal degree of pain relief, and it should be noted that inhalational anesthetics are drugs with low level analgesic effect, regional blocks and intravenous administration are used various types analgesics. IA is unacceptable in situations where there is severe respiratory failure, hypotension, inability to maintain airway patency (intubation).

How to choose the best anesthesia for your pet

Birds are one of the most stress-sensitive animal species. Even the simplest manipulations can cause a strong reaction from their body.

The idea of working with birds using sedation (anesthesia) was born quite a long time ago. But in our country it is for a long time It was impossible, since working with this group of animals under injection anesthesia is inconvenient; its use has more disadvantages than advantages. Only gas anesthesia, or gas anesthesia, allows you to work with birds safely and easily.

Why do we use gas anesthesia in our work?

Firstly, its safety. The drug we use is isoflurane. This substance practically does not undergo biotransformation, therefore harmful effects on the patient's body systems is practically absent.
Secondly, the drug enters the bird’s body during inhalation and is eliminated during exhalation. That is, the animal “falls asleep” very quickly (less than one minute) and “wakes up” just as quickly.
Thirdly, the supply of the drug is easy to control during manipulation, that is, to increase or decrease the concentration of gas supplied to the patient.
Fourthly, with the help of gas anesthesia it became possible to carry out many diagnostic manipulations, increasing their objectivity. Anesthesia removes the stress and pain factor during diagnostics, making the assessment of the patient’s condition more adequate.

With the qualified use of gas anesthesia, the mortality rate is less than one percent, that is, we can say that this is the most safe way anesthesia. Of course, there is also individual intolerance to the drug, and general state the patient, of course, affects the success of anesthesia. Before starting the manipulations, the attending physician will list all the pros and cons of using gas anesthesia in a specific situation.

Do not forget that most even tame poultry do not tolerate restraint, and when performing many long-term procedures, patient immobility is required. Thus, failure to use anesthesia increases the risk of injury to the patient and can even cause shock and death of the bird due to stress.

Without sedation, it is impossible to properly trim overgrown beaks and claws. With normal pruning, the bird will be rigidly fixed, every movement of the doctor will be seen and felt, all this will be perceived as a threat. The bird will be stressed, and the quality of performance will be low, since the bird will constantly try to escape. Sedation allows you to perform work on high level and the cosmetic effect achieved in this case will be maximum..

Even blood sampling must be performed under anesthesia. With this type of blood collection, trauma to the animal is minimal, in most species there is no trace of the procedure left, and in species that react to this with extensive hematomas, the affected areas become much less noticeable.

There is no need to talk about the advantages of using gas anesthesia during surgical interventions; this is the best and only true choice for birds. During simple surgical operations, isoflurane is used as monoanesthesia, but if the surgical intervention is complex, then the effect of gas anesthesia is supplemented with a number of other painkillers.

Unfortunately, the use of anesthesia increases the cost of the manipulation, since we do not dose the amount of drug per weight, but the concentration of gas supplied to the mask. Accordingly, on budgerigar it takes the same amount of drug as an average-sized mammal.

Gas anesthesia allowed the use in veterinary ornithology of techniques that were simply impossible before. It made it possible to reduce the stress load on animals and thereby significantly increase the percentage of cured patients.

Diseases in dogs are not uncommon. Some of them can be cured in as soon as possible and with minimal losses, but to treat others it is necessary to resort to surgical operations different levels difficulties. The problem is that the dog cannot be persuaded to lie still while the surgeon does his job. Even “minor” operations require anesthesia for dogs, and not only success largely depends on the quality of its implementation surgical intervention, but also all future life pet.

Anesthesia comes from an ancient Greek term that can literally be translated as “lack of sensation.” This “shortage” is achieved through anesthetic drugs that temporarily “disable” nerve fibers responsible for transmitting pain sensations.

In addition, anesthesia is characterized by a partial loss of muscle rigidity (that is, their relaxation), which also facilitates surgical intervention. All types of pain relief can be divided into two large groups: local and general (anesthesia).

General anesthesia for dogs

Regardless of the type of anesthesia, it always begins with premedication. This is the name of the “event” accompanied by the insertion of the lungs sedatives. Premedication is needed to calm the dog and prepare its body for deep, “full” anesthesia.

The absence of this stage is an almost 100% guarantee of development severe complications. General anesthesia can be divided into two broad types:

Mononarcosis (monovalent).
Polynarcosis.

In the first case, only one drug is used for anesthesia (occasionally two, if it is necessary to ensure their combined effect). As a rule, to such simple option are used for simple and short operations (many of which can be performed using only local anesthesia).

Accordingly, general polyvalent anesthesia involves the use of several drugs at once. It can be extremely difficult to take into account all the nuances of their interaction, but there is simply no other way out in cases where a complex and lengthy operation is ahead.

Parenteral anesthesia

This is the most common type of anesthesia, in which the active substance is administered intravenously into the dog’s body. The advantage of such anesthesia is the possibility of ideal dosing of the drug depending on the current condition of the animal being operated on. In addition, when intravenous administration the medicine begins to act very quickly.

Important! Almost all drugs for this type of anesthesia can cause hypoventilation.

Simply put, the process of gas exchange in them slows down greatly, which is why the operated dog may well die by suffocating. It is for this reason that intubation is always performed (i.e., a special tube is inserted into the trachea through which air flows directly into the lungs).

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Intubation is not always used. There is no particular need for it when the operation itself takes no more than 10 or 15 minutes. The same applies to cases where the upper respiratory organs are operated directly. True, even in such cases, the intubation apparatus is always kept at hand, since it may be needed at any time.

This is a pathology in which (due to congenital developmental anomalies vascular bed) blood from gastrointestinal tract goes directly into the general bloodstream. At the same time, the animal’s body is already in a state chronic intoxication, the introduction of sedatives intravenously can kill the dog.

Inhalation anesthesia

Currently, veterinarians use this technique quite actively. It is interesting that the first anesthesia was inhalation (it was given with chloroform vapor). Today, this technique has been somewhat modified, and vapors of the active substance are “pumped” into the lungs directly. To do this, the animal's trachea is intubated.

We can say that inhalation anesthesia is partly safer for the animal’s body, but still, in this case it is not without specific risks. Inhalation anesthesia is characterized by a significant drop in blood pressure (due to a pronounced vasodilator effect). During surgery, the dog's level must be constantly measured. blood pressure, since its fall to critical low values has an extremely detrimental effect on the condition of the kidneys and brain.

Inhalation anesthesia has at least one advantage - it allows free access to many organs respiratory system. It is also what veterinarians prefer to use when it is necessary to operate on the eyes, ears, nasal or oral cavity animal. With high-quality spraying of the active substance, it is possible to reduce its dose as much as possible.

Interesting! Inhalation anesthesia is rarely used: it is used when it is necessary to perform particularly complex and lengthy operations, additionally using parenteral anesthesia.

Local anesthesia for dogs

The most common type. In veterinary medicine, local anesthesia is used daily and very actively. Divided into several varieties.

Application anesthesia

The simplest method. It consists of applying “freezing” substances directly to the surface of the skin or mucous membranes. Contrary to popular belief, the lethality of this type of anesthesia is quite high. So, today on the shelves of pharmacies you can find a lot of pain-relieving “sports” sprays, the effect of which lasts several minutes. This may be quite sufficient for a simple surgical intervention.

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Infiltration anesthesia

Also simple and effective method, which consists in saturating the layers of skin and subcutaneous tissue anesthetic solutions. This procedure is performed using a regular syringe. It is used when performing simple and fleeting operations: for suturing, for example, or when removing an abscess.

Regional anesthesia

One of the most difficult but effective ways local anesthesia.

Firstly, its conductor type is distinguished. The point of the technique is to “impregnate” local nerve plexuses, nodes and nerve trunks anesthetic solutions.

Secondly, anesthesia is spinal. It is performed by injecting the drug directly between the arachnoid and soft shell spinal cord. This method allows you to temporarily “turn off” all sensations below the injection site.

The technique is good to use, for example, when caesarean section. In such cases, general anesthesia is extremely undesirable, since the “gave birth” bitch will need to feed the babies.

Epidural anesthesia

In this case, the drug is injected between the dura mater of the spinal cord and the spinal canal.

Contraindications for local anesthesia

It should be remembered that local anesthesia, for all its attractiveness (simplicity and low cost), is not always used. The reason is the presence of serious contraindications:

Local anesthesia is not used in cases where the operation (at least theoretically) may last longer than the duration of the painkiller.

The animal has a tendency to develop allergic reactions (however, in this case, you need to be extremely careful with general anesthesia).

Choleric character type. Simply put, it is better to immediately immerse “pocket” dogs with a quarrelsome and quarrelsome disposition into general anesthesia.

The same applies to cases where the dog is large and strong. It is far from certain that the owner will be able to hold him and calm him down.

Recovery from anesthesia

The faster the animal recovers from anesthesia, the shorter the operation, the lower the dose of the active substance.

To remove the dog, the veterinarian gradually (!) stops supplying the medication; in some cases, they use special drugs, blocking the action of the main medication. In addition, it is recommended to supply pure oxygen to the lungs: the latter helps accelerate metabolism and decomposition medicinal substances into its constituent components.

Risks and likelihood of complications

What are possible complications anesthesia? It is believed that sudden allergic reactions and intolerance to anesthetic drugs under normal conditions occur once in 100,000 uses. These reactions can range from mild swelling at the injection site to death.

Remember! Always and under all conditions, there is some chance that the body of a particular animal will react inadequately to a particular drug, even if the latter has been used for medical and veterinary purposes for decades.

In almost 100% of cases when general anesthesia problems will arise (quite possibly fatal) if the dog has not “fasted” for at least 12 hours before the operation. Well-fed dog may die during surgery. The problem is that with general anesthesia, the principle of muscle innervation changes greatly.

The main task veterinarian- preserving the life of the animal. Doesn't matter we're talking about about diseases internal organs: liver, kidneys, cardiovascular systems s; lesions of the musculoskeletal system or other organs and systems. Some diseases can be cured conservative methods(drugs that are administered orally and by injection), but some require surgery. In this case, there is a need for anesthesia.

In our clinic, anesthesiological care is entrusted to an anesthesiologist, whose main task is to ensure that during medicated sleep the life and health of the animal were safe. To reduce the risks associated with the administration of anesthesia drugs before surgery, it is necessary to conduct a minimum set of studies, which includes a general blood test, blood biochemistry and ultrasound examination of the heart (echocardiography). In some cases it is required additional research: Ultrasound of the abdominal organs, radiography chest, general urine test or other. Preoperative examination is especially important for middle-aged and elderly animals.

A veterinary anesthesiologist conducts a preoperative clinical examination and analyzes data laboratory research and the animal's medical history. After this, the doctor determines the optimal combinations of drugs for sedation, routes and methods of their administration, which depends on the condition of the animal, its age, anatomical and physiological characteristics, complexity and duration of the planned operation, the required depth of medicated sleep and the level of anesthesia. Our clinic has the entire arsenal of available drugs to provide high-quality anesthesiological support to the patient. During medicated sleep, the following indicators are monitored: ECG, blood oxygen saturation, level of carbon dioxide in the blood, respiratory rate, heart rate, pulse pattern, blood pressure.

The most convenient, controlled and safe is gas anesthesia for cats and dogs. The clinic has modern equipment for its implementation: an anesthesia machine, an artificial lung ventilation device, an oxygen concentrator, a patient monitor with a capnometry module.

General view of the anesthesia machine and patient monitor.

Our clinic is one of the few in Nizhny Novgorod introduced into clinical practice and has mastered the technique of gas anesthesia in animals. Greatest Reasons for its use in elderly animals, in animals with pathologies of the liver, kidneys, cardiovascular system, during long-term and technical complex operations: on the abdominal organs and chest cavity, spinal column, head organs. To achieve complete analgesia, our doctors have the technique of epidural anesthesia for animals, when an anesthetic is injected into the space around the spinal cord, blocking the conduction of impulses along it. In this case, the animal not only does not feel pain, but also does not perceive any unpleasant sensations from the area of the operation.

After inhalation anesthesia the animals quickly come to their senses, after about an hour they can move independently, feel normal and are able to go home with the owner, which makes possible to carry out some operations are performed on an outpatient basis.

Our doctors treat general anesthesia (anesthesia) with full responsibility and are aware possible risks and constantly strive to improve the safety of this procedure, create comfortable conditions for animals during and after medicated sleep.

Anesthesiologists widely use inhalational gas anesthetic NITRON OXIDE. IN late 1980s inert gas entered foreign anesthesiological practice XENON.

Nitrous oxide is a colorless gas with a characteristic odor, stored in metal cylinders under a pressure of 50 atm in a liquid state, does not burn, but supports combustion. Its mixtures with anesthetics of the group of volatile liquids are explosive in certain concentrations.

In narcotic concentrations (20 - 30%) of nitrous oxide causes euphoria (laughing gas) and strong analgesia. At a concentration of 20% it provides pain relief to the same extent as 15 mg of morphine.

Nitrous oxide is poorly soluble in the blood, but dissolves well in the lipids of the central nervous system, so anesthesia occurs very quickly. During anesthesia, even when using high concentrations of nitrous oxide (95%), complete suppression of reflexes is not achieved and the tone of skeletal muscles is not reduced. To obtain deep anesthesia, nitrous oxide is combined with inhalational and non-inhalational anesthetics and muscle relaxants. After anesthesia, depression and other aftereffects do not occur, but diffusion hypoxia is possible - the transport of oxygen into the blood is disrupted due to the intense diffusion of the gas anesthetic into the lumen of the alveoli. To avoid hypoxia, oxygen is inhaled for 4 to 5 minutes after the end of anesthesia.

Nitrous oxide during mononarcosis does not depress the respiratory and vasomotor centers, but during combined and potentiated anesthesia it increases respiratory depression. In high concentrations it disrupts cardiac activity. Moderately increases blood pressure due to the release of adrenaline from the adrenal glands and sensitization of vascular a-adrenergic receptors.

With repeated nitrous oxide anesthesia, macrocytic anemia, leukopenia and thrombocytopenia may develop (inhibits vitamin-dependent AT 12 enzyme methionine synthetase). U medical personnel cases of anemia, neuropathy, teratogenic and embryonic toxic effect.

In the body cavities, one molecule of air nitrogen is replaced by 35 molecules of nitrous oxide. During anesthesia, pressure increases in the middle ear, pneumothorax cavity, renal calyces and pelvis, and intestinal loops. There is a danger of air embolism, damage eardrum, compression of the lungs and kidneys.

Nitrous oxide is used for induction anesthesia (80% nitrous oxide and 20% oxygen), combined and potentiated anesthesia (60 - 65% nitrous oxide and 35 - 40% oxygen), pain relief for childbirth, trauma, myocardial infarction, acute pancreatitis(20% nitrous oxide). Ambulances are equipped with a nitrous oxide inhalation device.

Nitrous oxide anesthesia is contraindicated in hypoxia and serious illnesses lungs, accompanied by impaired gas exchange in the alveoli. In patients with angina pectoris and myocardial infarction, therapeutic analgesia with nitrous oxide is not used in cases of severe pathology nervous system, chronic alcoholism, alcohol intoxication(danger of hallucinations, excitement). Nitrous oxide is not used for pneumoencephalography and operations in otorhinolaryngology.

The inert gas xenon is considered the best alternative nitrous oxide, since it has a more pronounced anesthetic effect, indifference and environmental safety. The ability of xenon to cause anesthesia was discovered in connection with the practice of deep-sea diving and the development of hyperbaric physiology.

Xenon is colorless, does not burn and has no odor; upon contact with the mucous membrane of the mouth, it creates a bitter sensation on the tongue metallic taste. It is characterized by low viscosity and high solubility in lipids, and is excreted unchanged by the lungs. A xenon-saving anesthesia technology has been developed that includes a minimum flow and a recycling system for repeated reuse of gas. This technology successfully solves the practically important problem of the shortage and high cost of xenon.

In the mechanism of the anesthetic effect of xenon, blockade of cytoreceptors of excitatory neurotransmitters - N-cholinergic receptors, NMDA-glutamic acid receptors, as well as activation of receptors for the inhibitory neurotransmitter glycine. When interacting with cytoreceptors, xenon acts as a proton-binding cluster and forms complexes with cations HCO +, NH 2 +, HNCH +. Xenon exhibits antioxidant and immunostimulant properties, reduces the release of hydrocortisone and adrenaline from the adrenal glands.

Anesthesia with xenon (80%) mixed with oxygen (20%) occurs in four stages:

· paralgesia and hypoalgesia(after 1 - 2 minutes) - heaviness in lower limbs, lower back, epigastrium, paresthesia skin, tinnitus and a feeling of compression of the head, consciousness is clear, verbal contact is completely preserved, the threshold of pain sensitivity doubles;

· euphoria and psychomotor activity(at 2 - 3 minutes) - euphoria, talkativeness, increased psychomotor activity, hypertonicity skeletal muscles, uneven, rapid breathing, tachycardia, moderate arterial hypertension, reflexes are preserved (the effects of excitation are much weaker than with ether anesthesia);

· analgesia and partial amnesia(after 4 - 5 minutes) - severe analgesia, drowsiness, consciousness is inhibited, unrealistic visual images, breathing is rare, uniform, pulse and blood pressure return to original level, skin pink, dry, warm;

· surgical anesthesia(after 5 - 7 minutes) - pain sensitivity, consciousness, pharyngeal and conjunctival reflexes are lost, pupils are constricted, eyeballs They are first in a position of divergent strabismus, then they are centered, breathing and blood circulation are maintained at a normal level.

Awakening after stopping xenon inhalation is quick and pleasant, regardless of the duration of anesthesia. After 2 - 3 minutes, consciousness is restored with complete amnesia and preservation of post-anesthesia analgesia. After 4 - 5 minutes, orientation in time and space appears. As after anesthesia with nitrous oxide, diffusion hypoxia is possible, so it is necessary to compensate for pulmonary ventilation in the first 2 to 3 minutes after the anesthetic is turned off.

Xenon in the mask version of mononarcosis, inhibiting respiratory center, reduces respiratory rate, but increases tidal volume and blood oxygenation level. The combination of xenon with narcotic analgesics is not recommended.

Xenon does not cause significant changes in pulse or heart contraction force, and at the beginning of inhalation it increases cerebral blood flow. At the most traumatic stages of the operation, blood pressure fluctuations do not exceed 10 - 15 mm Hg; patients with arterial hypertension do not experience dangerous increases in blood pressure. In the experiment, xenon inhalation during the early reperfusion period (in the first 15 minutes) reduced the size of the infarct zone.

Xenon can be recommended for anesthesia in patients with a compromised cardiovascular system, in pediatric surgery, during painful manipulations, dressings, for pain relief in childbirth, relief of painful attacks (angina pectoris, myocardial infarction, renal and hepatic colic). Xenon anesthesia is contraindicated during neurosurgical operations.

NON-INHALATION ANALCOSIS DRUGS

Non-inhalation anesthetics injected into a vein, into muscles and intraosseously. In 1909, non-inhalation anesthesia with hedonal was performed by surgeon S. P. Fedorov in the hospital surgical clinic Military Medical Academy of St. Petersburg for lower leg amputation. The operation was completed with complete clinical effect and without complications. The hypnotic drug of the urethane group hedonal was proposed by the founder of domestic pharmacology N.P. Kravkov. Hedonal does not depress the respiratory center and only moderately reduces blood pressure (this drug is not currently used due to its weak anesthetic effect). Hedonal anesthesia soon became known abroad, where it was called “Russian anesthesia.”

N.P. Kravkov also proposed combined anesthesia with hedonal and chloroform. Sodium thiopental has been used since 1935.

Non-inhalation anesthetics are divided into three groups: Short-acting drugs (3 - 5 min)

· PROPANIDID(SOMBREVIN)

· PROPOFOL (DIPRIVAN, RECOFOL)

Drugs average duration actions (20 - 30 min)

· KETAMINE(CALIPSOL, KETALAR, KETANEST)

· MIDAZOLAM(DORMICUM, FLORMIDAL)

· HEXENAL(HEXOBARBITAL SODIUM)

· THIOPENTAL SODIUM(PENTOTHAL) Drugs long acting(0.5 - 2 h)

· SODIUM OXYBUTYRATE

PROPANIDID- ester, by chemical structure close to novocaine. When administered into a vein, it has an anesthetic effect within 3-5 minutes, as it undergoes rapid hydrolysis by blood pseudocholinesterase and is redistributed into adipose tissue. Blocks sodium channels membranes of neurons and disrupts depolarization. It turns off consciousness and in subnarcotic doses has only a weak analgesic effect.

Propanidide selectively stimulates the motor areas of the cortex, therefore causing muscle tension, shudders, increases spinal reflexes. Activates the vomiting and respiratory centers. During anesthesia with propanidide, hyperventilation is observed in the first 20–30 s, followed by hypocapnia and respiratory arrest for 10–15 s. Reduces heart contractions (to the point of cardiac arrest) and causes arterial hypotension, blocking β - adrenergic receptors of the heart. There is a risk when prescribing propanidide allergic reactions caused by the release of histamine ( anaphylactic shock, bronchospasm). Cross-allergy with novocaine is possible.

Propanidide is contraindicated in shock, liver disease, kidney failure, and is used with caution in cases of coronary circulation disorders, heart failure, and arterial hypertension.

PROPOPHOL(2,6-diisopropylphenol) is used in the form of an isotonic fat emulsion for injection into a vein (1 ml contains 100 mg of lipids). He is the antagonist NMDA-glutamic acid receptors, enhances GABAergic inhibition, blocks voltage-dependent calcium channels of neurons. It has a neuroprotective effect and accelerates the recovery of brain function after hypoxic damage. Inhibits lipid peroxidation, proliferation T-lymphocytes, their release of cytokines, normalizes the production of prostaglandins. The extrahepatic component plays a significant role in the metabolism of propofol; inactive metabolites are excreted by the kidneys.

Propofol induces anesthesia within 30 s. Severe pain may occur at the injection site, but phlebitis and thrombosis are rare. Propofol is used for induction of anesthesia, maintenance of anesthesia, sedative effect without turning off consciousness in patients undergoing diagnostic procedures And intensive care. Combine with narcotic analgesics and nitrous oxide (or other inhalational anesthetics).

During induction of anesthesia, twitching of skeletal muscles and convulsions sometimes appear, respiratory arrest develops within 30 s, due to a decrease in the sensitivity of the respiratory center to carbon dioxide and acidosis. Oppression of the respiratory center is potentiated by narcotic analgesics. Propofol, by dilating peripheral vessels, short-term reduces blood pressure in 30% of patients. Causes bradycardia, reduces cerebral blood flow and oxygen consumption by brain tissue. Anesthesia is not characterized by arrhythmia and myocardial ischemia, although the arrhythmogenic effect of adrenaline is potentiated.

Awakening after propofol anesthesia is rapid, convulsions, tremors, hallucinations, asthenia, nausea and vomiting occasionally occur, and intracranial pressure increases. There are known cases of postoperative fever, sexual disinhibition, and anaphylactic reactions. Propofol fat emulsion is a good medium for the proliferation of microorganisms.

Therefore, when using it, asepsis must be carefully observed. Average frequency bacterial contamination of propofol solution is currently 6.3%. The safe duration of propofol fat emulsion infusion should not exceed 8 to 12 hours.

To reduce the risk of septic complications during propofol infusion, it has been proposed combination drug with ethylenediaminetetraacetate - DIPRIVAN-EDTA. EDTA, added in a minimum concentration of 0.01 - 0.05%, effectively suppresses the proliferation of pathogenic bacteria, but does not accelerate the removal of calcium and magnesium ions from the body.

Propofol is contraindicated for allergies, hyperlipidemia, disorders cerebral circulation, pregnancy (penetrates the placenta and causes neonatal depression), children under one month of age. Anesthesia with propofol is carried out with caution in patients with epilepsy, pathology of the respiratory, cardiovascular systems, liver and kidneys, and hypovolemia.

KETAMINE causes anesthesia when injected into a vein for 5 - 10 minutes, when injected into muscles - for 30 minutes. There is experience with the epidural use of ketamine, which prolongs the effect up to 10–12 hours. The metabolite of ketamine, norketamine, has an analgesic effect for another 3–4 hours after the end of anesthesia.

Ketamine anesthesia is called dissociative anesthesia: the drugged person has no pain (felt somewhere to the side), consciousness is partially lost, but reflexes are preserved, and the tone of the skeletal muscles increases. The drug disrupts the conduction of impulses along specific and nonspecific pathways to the associative zones of the cortex, in particular, it interrupts thalamo-cortical connections.

The synaptic mechanisms of action of ketamine are diverse. It is a non-competitive antagonist of the excitatory brain mediators glutamic and aspartic acids in relation to NMDA-receptors (NMDA-N-methyl- D-aspartate). These receptors activate sodium, potassium and calcium channels in neuronal membranes. When receptors are blocked, depolarization is disrupted. In addition, ketamine stimulates the release of enkephalins and β-endorphin; inhibits the neuronal uptake of serotonin and norepinephrine. The latter effect is manifested by tachycardia, increased blood pressure and intracranial pressure. Ketamine dilates the bronchi.

When recovering from ketamine anesthesia, delirium, hallucinations, and motor agitation are possible (these undesirable phenomena are prevented by the administration of droperidol or tranquilizers).

Important therapeutic effect ketamine is neuroprotective. As is known, in the first minutes of brain hypoxia, excitatory mediators - glutamic and aspartic acids - are released. Subsequent activation NMDA-receptors, increasing

in the intracellular environment, the concentration of sodium and calcium ions and osmotic pressure cause swelling and death of neurons. Ketamine as an antagonist NMDA-receptors eliminates the overload of neurons with ions and the associated neurological deficit.

Contraindications to the use of ketamine are cerebrovascular accidents, arterial hypertension, eclampsia, heart failure, epilepsy and other convulsive diseases.

MIDAZOLAM- a non-inhalation anesthetic with a benzodiazepine structure. When injected into a vein, it causes anesthesia within 15 minutes; when injected into the muscles, the duration of action is 20 minutes. Affects benzodiazepine receptors and allosterically enhances the cooperation of GABA with GABA type receptors A. Like tranquilizers, it has muscle relaxant and anticonvulsant effects.

Midazolam anesthesia is performed only with artificial ventilation lungs, as it significantly depresses the respiratory center. This drug is contraindicated in myasthenia gravis, circulatory failure, in the first 3 months. pregnancy.

Barbiturates HEXENAL And THIOPENTAL SODIUM after injection into a vein, anesthesia is induced very quickly - “at the end of the needle”, the anesthetic effect lasts 20 - 25 minutes. The fate of hexenal and thiopental is different. Hexenal is rapidly oxidized by cytochrome R- 450 liver into metabolites without anesthetic effects. Thiopental is deposited in adipose tissue and oxidized in the liver at a rate of 15% of the dose per hour. Complete oxidation of a single dose of thiopental occurs within 40 hours. The release of thiopental from fat depots causes post-anesthesia drowsiness and depression.

The sedative, hypnotic, anticonvulsant and anesthetic effects of barbiturates are due to inhibition reticular formation midbrain and weakening of its activating influence on the cerebral cortex. Barbiturates, as agonists of barbiturate receptors at GABAergic synapses, allosterically enhance the effect of GABA on GABA A receptors.

During anesthesia, reflexes are not completely suppressed, the tone of skeletal muscles increases (H-cholinomimetic effect). Laryngeal intubation without the use of muscle relaxants is unacceptable due to the risk of laryngospasm. Barbiturates do not have an independent analgesic effect.

Barbiturates depress the respiratory center, reducing its sensitivity to carbon dioxide and acidosis, but not to reflex hypoxic stimuli from the carotid glomeruli. They increase the secretion of bronchial mucus, independent of cholinergic receptors and not eliminated by atropine. Stimulate the center vagus nerve with the development of bradycardia and bronchospasm. They cause arterial hypotension because they inhibit the vasomotor center and block the sympathetic ganglia.

Hexenal and thiopental sodium are contraindicated in diseases of the liver, kidneys, sepsis, fever, hypoxia, heart failure, and inflammatory processes in the nasopharynx. Hexenal is not administered to patients with paralytic intestinal obstruction (severely inhibits motility); thiopental sodium is not used for porphyria, shock, collapse, diabetes mellitus, bronchial asthma.

Non-inhalation anesthetics are used for induction, combined anesthesia and independently during short-term operations. IN outpatient practice Propanidide, which has no aftereffect, is especially convenient. Midazolam is used for premedication and is also prescribed orally as sleeping pills and a tranquilizer.

SODIUM OXYBUTYRATE(GHB) when administered into a vein causes anesthesia after 30 - 40 minutes, lasting 1.5 - 3 hours.

This drug is converted into the GABA mediator, which regulates inhibition in many parts of the central nervous system (cerebral cortex, cerebellum, caudate nucleus, pallidum, spinal cord). GHB and GABA reduce the release of excitatory transmitters and enhance postsynaptic inhibition by affecting GABA A receptors. During anesthesia with sodium hydroxybutyrate, reflexes are partially preserved, although strong muscle relaxation occurs. Relaxation of skeletal muscles is due to the specific inhibitory effect of GABA on the spinal cord.

Sodium hydroxybutyrate does not inhibit the respiratory, vasomotor centers, or the heart; it moderately increases blood pressure, sensitizing the a-adrenergic receptors of blood vessels to the action of catecholamines. It is a strong antihypoxic agent in the brain, heart, and retina.

GHB, turning into succinic semialdehyde, forms the GHB system - succinic semialdehyde. This system, participating in the transport of hydrogen ions in the respiratory chain of mitochondria, improves the oxidation of pyruvic and lactic acids with the elimination of intracellular acidosis. GHB is converted through succinic semialdehyde to succinic acid, an important oxidation substrate. As a result of these metabolic effects, the synthesis of macroergs is enhanced, and potassium ions penetrate into cells more easily (hypokaligistia is eliminated, but hypokalemia may occur, which will require correction with potassium chloride).

Sodium hydroxybutyrate is used for introductory and basic anesthesia, pain relief during labor, as antishock agent, in complex therapy of hypoxia, including cerebral hypoxia. It is contraindicated for myasthenia gravis, hypokalemia, and is prescribed with caution for toxicosis of pregnancy accompanied by arterial hypertension, as well as for people whose work requires rapid mental and motor reactions.

ETHANOL

Ethanol ( ethyl alcohol, wine alcohol, ethanol) is a transparent volatile liquid with a characteristic alcoholic odor and pungent taste, easily flammable, burns, and mixes in any proportion with water, ether, and chloroform.

The word "alcohol" comes from Arabic words (al-)kuhl - antimony, antimony; kuhul - alcohol, alcohol; kahala- grease, tint. In the Middle Ages in Europe the word alco(h)ol used as the name of the finest powder, dust or purified (distilled) water. The word "alcohol" is of Latin origin: spiro- I blow, I breathe. In Gallic, alcohol is usquebaugh(water of life).

Ethyl alcohol is a good solvent due to the combination of a polar hydroxyl and a non-polar ethyl radical in the molecule; it is used for the preparation of tinctures, extracts and dosage forms for external use. The body contains a small amount of endogenous alcohol; in the blood its concentration ranges from 0.004 to 0.01%.

The invention of the distillation method and the first production of alcohol is associated with the name of the Arab alchemist Rages, who, in his search for the “philosopher’s stone,” accidentally isolated ethyl alcohol. In Europe, alcohol was produced in the 13th century. and was initially used as a universal remedy. Its use went beyond the control of doctors in the 14th century. during the plague pandemic.

A great contribution to the study of the toxic effects of ethyl alcohol was made by domestic physiologists, pharmacologists and clinicians I.M. Sechenov, I. P. Pavlov, N. P. Kravkov, V. M. Bekhterev, S. S. Korsakov.

Ethyl alcohol has local, reflex and resorptive effects. IN medical practice mainly used local action. Sometimes weak solutions of alcohol in the form of table wines, beer, kumiss are prescribed for a short time and in a limited volume to patients during the period of convalescence to increase appetite and restore function. digestive tract. In critical cases, ethyl alcohol is added to mixtures for parenteral nutrition(50 - 70 g per day). As you know, when 100 g of ethanol is oxidized in the body, approximately 700 kcal of energy is released.

Use small quantities red wine (50 ml in terms of absolute alcohol 2 - 3 times a day) reduces platelet aggregation, the content of atherogenic low-density lipoproteins, and glucose levels in patients diabetes mellitus type 2, increases the content of lipoproteins that counteract atherosclerosis high density. It is possible that antioxidant polyphenols in red wine have an anti-atherosclerotic effect, although this has not been experimentally confirmed.

Taking strong alcoholic drinks to increase resistance to cold is not justified, since under the influence of ethyl alcohol not only heat production increases, but heat transfer increases to a much greater extent. Extension skin vessels creates a false sensation of warmth, at the same time heat loss due to sweating increases, and mental control over the danger of hypothermia is lost. The use of small doses of ethyl alcohol is acceptable for the prevention of colds after hypothermia has occurred and the victim has returned to warmth.