Isoflurane

Isoflurane is a medicinal product that belongs to the group of agents used in anesthesiology. Its purpose is justified when there is a need for inhalation administration of the drug to reduce sensitivity to pain by introducing the patient into deep sleep. Reversible inhibition of the central nervous system, which occurs under the influence of anesthesia, causes a temporary disconnection of consciousness and memory, a marked decrease in certain reflexes, relaxation of the muscles and a complete loss of sensitivity, which is necessary in the case of surgical intervention.

[1], [2], [3], [4], [5], [6], [7]

Indications Isoflurane

"Isoflurane" is an inhalation anesthesia. It may be required during surgical operations with the requirement of general anesthesia. Often cases of inhalation anesthesia and in obstetric practice, such as anesthesia in cesarean section, and when there are small surgical interventions that do not require disconnection of consciousness.

[8], [9], [10]

Release form

The preparation is made in the form of 100% solution of isoflurane for inhalations in bottles of dark glass of 100 and 250 ml. Both forms of release of a strong anesthetic used in surgery and obstetrics are vials filled with a transparent, thick, non-flammable liquid that does not have a specific color.

Inhalations are carried out with the help of special calibrated anesthetic evaporators that provide and maintain the necessary concentration of the solution supplied to the patient, depending on the stage of anesthesia.

[11], [12], [13], [14], [15]

Pharmacodynamics

Isoflurane is an inhalational anesthetic used for general anesthesia, which equally effectively provides an introductory anesthesia (induction of anesthesia), patient maintenance during surgery and rapid recovery after anesthesia.

Under its action, there is a rapid loss of sensitivity in patients, a decrease in pharyngeal and laryngeal reflexes, relieving muscle tension and relaxation, which is necessary for many cavitary operations.

The use of isoflurane for inhalation anesthesia makes it easy to control the depth (level) of anesthesia, which is very important during the operation, as exceeding the dose and effectiveness of the drug can lead to tragic consequences, and insufficient anesthesia can lead to premature return of sensitivity or awakening of the patient.

The depth of anesthesia has a significant effect on blood pressure. Reduction of pressure in the induction stage occurs due to the expansion of arterial and venous vessels, while in the surgical phase the blood pressure is normalized. A further increase in the depth of anesthesia can lead to a proportional decrease in pressure, up to the development of arterial hypotension.

The drug significantly weakens independent breathing, but does not affect the heart rhythm and the release of blood with a contraction of the myocardium. An increase in the heart rate during artificial ventilation, under the condition of normal stress of carbon dioxide in the arterial blood, is caused by the need to preserve the minute volume of the heart.

With superficial anesthesia, the drug has no effect on cerebral blood flow, but with an increase in anesthesia, blood flow may increase, causing an increase in cerebrospinal pressure. Stabilization of the state is due to the reduction of hyperventilation on the eve or during the anesthesia. It is worthwhile to resort to hyperventilation if the patient has increased intracranial pressure.

Isoflurane exerts a slight irritant effect due to the scarcely perceptible acute odor of the ether, which can negatively affect the induction of the gaseous substance; nevertheless, the rate of development of the processes at the initial anesthesia and at the final stage remains quite large.

The parameters of EEG and vascular activity during anesthesia with isoflurane remain normal. Their change is observed only in isolated cases.

The use of the drug does not cause an increase in the secretion of the secretion of the salivary and triunebronchial glands (saliva and sputum).

[16], [17], [18], [19], [20], [21], [22], [23], [24]

Pharmacokinetics

The active substance of the preparation is very slightly soluble in body fluids. This leads to a rapid development of partial pressure in the alveoli, which is necessary for anesthesia.

Isoflurane is released from the body quickly enough by the respiratory tract, and only a small amount (less than 0.2%) is excreted by the kidneys in the form of metabolites. The concentration of organic and inorganic fluorides formed as a result of metabolism and decomposition of isoflurane is quite low and is considered safe for the kidneys, nevertheless, patients with severe kidney disorders are to be treated with caution.

[25], [26], [27], [28], [29], [30]

Dosing and administration

Anesthesia with the help of the preparation "Izufloran", both induction and in all subsequent stages, is carried out by means of special evaporators.

Preliminary preparation of patients for anesthesia is carried out with the use of medicines corresponding to the selected type of anesthesia. Choosing for narcosis "Izufloran" it is necessary to take into account the ability of the latter to exert a depressing effect on breathing. Drugs that inhibit the conduction of nerve impulses can be used to reduce salivation (which is not necessarily the case with isofloran), but it must be taken into account that they are able to enhance the effect of "Izufloran" in increasing the frequency of cardiac contractions.

Introductory (induction) anesthesia. The recommended initial dose of isfloran in a mixture for anesthesia is 0.5%. To avoid the appearance of cough with inhalation of isfloran, anesthesia should be started not with an inhalation method, but with iv injections of short-acting barbiturates or other analgesics used in anesthesia. Cough can appear in both adult patients and in babies, which is associated with an increase in saliva secretion.

To achieve a surgical level of anesthesia, the concentration of the drug should be increased to 1.5-3%. In this case, the operation can be started after 8-10 minutes.

Surgical stage of anesthesia. A sufficient level of anesthesia is achieved with an isofloran concentration of 1 to 2.5% in a mixture of oxygen with 70% nitric oxide. When using one oxygen or with a small amount of nitric oxide, the concentration of isofloran should be increased to 1.5-3.5%.

The decrease in blood pressure at this stage of anesthesia depends on the depth of anesthesia. If a severe reduction in pressure is observed with deep anesthesia, correction of the dose of isofloran is required. Controlled hypotension with artificial ventilation is achieved with an isoflurane concentration of 2.5-4%. To reduce the dose of isfloran necessary in this case it is possible with the help of preventive reception of "Clonidine".

At the stage of anesthesia, the concentration of isoflurane gradually decreases from 0.5% at the time of closure of the surgical wound to 0 at the end of the operation. At this stage, it is necessary to make sure that the action of muscle relaxants and various blockers used in anesthesia is discontinued.

When the action of all anesthetics is over, the patient's airway for some time is ventilated with pure oxygen for anesthesia. Exit from the action of anesthesia occurs quickly and easily.

The activity of anesthetics can be measured in MAK (minimal alveolar concentration). This is the lowest effective dose of the drug, which depends on the age of the patient.

The highest MAC score in children of the first to 6-year-old age (the first month of life - 1.6%, in 1-6 months the indicator increases to 1.87, then to a year decreases slightly and is 1.8%, and from year to six years back to the level of 1.6%). In this case preterm infants have an IUD below (in 6-7 months - 1.28%, in 8 months - 1.41%). In children over 6 years of age, adolescents and in adolescence, the MAC score is 1.25%.

In adults, the minimum concentration is relatively low. For young people from 20 to 40 years, the MAC will be within 1.18%, for middle-aged people (up to about 60 years), this figure is reduced to 1.15%, for old people is 1.05%.

These figures are valid if isoflurane is used in combination with oxygen, if the mixture is oxygen, with 70% nitrous oxide (for children - with 75% nitrous oxide), the concentration of isoflurane should be significantly reduced (more than 2 times). For example, for middle-aged people, the MAC score will be 0.50%, for young people it will be 0.56%, for elderly people it will decrease to 0.37%.

At first glance, the figures are so small that they hardly differ from each other, but in medicine, and even more so in anesthesiology, every hundredth of a percent is a quantity equal to a person's life. Above, only approximate figures are given, from which anesthetists are repelled, calculating the necessary concentration of isoflurane in the gas. In fact, this value may depend on the state of health of the patient, and on certain physiological characteristics of his organism, in particular, on the tolerability of the drug.

[37], [38], [39], [40], [41], [42]

Use Isoflurane during pregnancy

As for the use of "Isoflurane" during pregnancy, there are no precise instructions in the manufacturer's instructions. It is not recommended to use isoflurane in the first trimester of pregnancy. This is due to the possible toxicity of the drug and the negative impact on reproductive function. Studies in this area were carried out only on animals, there is no influence on people.

It is generally believed that during pregnancy, it is better not to use anesthetics. If there is an extreme need, the use of isoflurane should be carried out taking into account all risks to the health and life of the mother and fetus.

When conducting ancestral operations under anesthesia (for example, cesarean section), it is necessary to use a mixture of oxygen with nitrogen oxide, then the recommended dose of isoflurane will be from 0.5 to 0.75%.

It is undesirable to use Isoflurane for gynecological surgery (for example, gynecological cleansing), conducted under anesthesia, since in this case the risk of high blood loss increases.

During breastfeeding, the use of anesthesia with isoflurane is not prohibited. But the baby's breastfeeding will have to be interrupted until all the anesthesia leaves the mother's body.

Contraindications

Like most medical preparations, "Isoflurane" has its own contraindications for use. One of such contraindications is malignant hyperpyrexia (or otherwise, hyperthermia), manifested in a sharp increase in body temperature during anesthesia, which threatens the patient's life. This pathology is hereditary and occurs under the influence of drugs used for anesthesia.

For this reason, the use of isoflurane is unacceptable in patients who have already experienced similar manifestations or are implied a hereditary predisposition to the disease. The latter concerns both cases of illness in the family, and the development of diseases that can lead to increased muscle metabolism (various types of myopathy, myotonia, King's syndrome, muscular dystrophy, etc.).

Do not use an anesthetic with isoflurane for jaundice and severe liver damage. And also, if a person has a marked fever accompanied by a fever (fever).

It is unacceptable to use "Isofloran" if a person has increased sensitivity to this solution or anesthetic preparations containing halogens. The same applies to cases of eosinophilia, when, under the influence of the above described drugs, the level of eosinophilic cells in the blood increases, performing a protective function in the composition of the leukocyte formula.

[31], [32], [33]

Side effects Isoflurane

Use of the drug "Isoflurane" for anesthesia is sometimes accompanied by undesirable symptoms related to the side effects of this drug. The most frequently occurring reactions characteristic of all halogen-containing drugs used in anesthesia include heart rhythm disturbances, increased blood pressure and respiratory center depression.

"Isoflurane", like any other anesthetic, can cause such unpleasant symptoms as nausea accompanied by vomiting, short-term changes in the blood composition towards increase in leukocytes, chills, intestinal obstruction, loss of consciousness after the operation and anesthesia.

Sometimes patients are slowed down by heart rhythm (bradycardia) or increased (tachycardia), hemorrhages in various organs, increased levels of carboxyhemoglobin (hemoglobin compounds with carbon monoxide), development of extreme myopathy (rhabdomyolysis). Frequent cases of the appearance of mood swings on the soil of anesthesia, but the bronchospasm caused by the use of "Isoflurane" is a rare phenomenon.

Sometimes doctors have to face such a side effect of the drug as the development (against the background of its use) of liver disorders of varying severity, ranging from jaundice and hepatitis and ending with necrosis of liver tissue and death. In childhood, cases of laryngospasm caused by excessive salivation are not uncommon.

Rarely, there were reactions associated with malignant hyperthermia, an increase in the level of potassium in the blood plasma and other changes in its composition, anaphylactic reactions, cardiac arrest.

[34], [35], [36]

Overdose

An incorrectly calculated level of isoflurane can lead to an overdose of the drug, which manifests itself in a significant inhibition of respiratory function and a decrease in blood pressure to critical values. The decrease in blood pressure and in this case is associated not with myocardial depression, but with the vasodilating effect of isoflurane.

If the fact of overdose is established, immediately stop the injection and carry out preventive ventilation of the lungs with pure oxygen to remove the anesthetic residues. This is a very unpleasant situation, given that this can happen during the operation. In this case, oxygen ventilation is replaced by controlled ventilation with small doses of isoflurane.

[43], [44], [45]

Interactions with other drugs

The use of "Isofruran" for anesthesia should be carried out taking into account information about drug interaction with other drugs.

To relax the muscles needed in the case of cavitary and some other operations, the action of isoflurane is sometimes supplemented with drugs from the group of muscle relaxants. In this case, isoflurane enhances their effect, so the dose of muscle relaxants taking into account this point should be relatively small. To reduce the effectiveness of non-depolarizing drugs to relax the skeletal muscles, use "Proserin" (the active substance - neostigmine methyl sulfate), which does not react with isoflurane.

Simultaneous effects on the human body of izflorana and adrenaline or amphetamines can lead to the development of arrhythmia. If the patient has no heart problems, the dose of adrenaline should not be more than 3 micrograms per kilogram of weight, if there are violations of the heart rhythm, the dosage will have to be significantly reduced. It is even better to stop taking drugs that belong to the class of beta sympatics, at least a couple of days before the proposed date of the operation.

Parallel reception of isoflurane and vasodilator drugs can lead to a significant decrease in blood pressure.

Simultaneous reception of preparations for anesthesia and MAO inhibitors is inadmissible. This is due to the fact that the latter increase the effect of isofloran and other similar preparations. Stop taking MAO inhibitors should be at least 2 weeks before the scheduled date of the operation.

Some drugs, in particular beta-blockers, are able to protect the patient's heart from possible arrhythmia caused by the use of isoflurane. If necessary, to increase the heart rate and provide the necessary narrowing of the vessels, you can use the appropriate sympathomimetics, a list of which should be for each anesthesiologist.

The drug "Izomiazid", used in the therapy and prevention of tuberculosis, is able to increase the susceptibility of the liver to the toxic effect of isoflurane, therefore, it is desirable to stop taking the above drug at least 7 days before the date of surgery in order to protect the liver from destruction.

Opioid (narcotic) analgesics (Morphine, Omnipon, Isopromedol, Methadone, and others) used in parallel with isoflurane increase the function of respiratory depression, which can be dangerous for the patient's life.

When the CO ₂ abrasives dry out , used in anesthetic apparatus, the administration of isoflurane can cause an increase in the blood of carboxyhemoglobin, which has a strong toxic effect, which in turn leads to the destruction of liver cells.

In order to prevent violations of the liver, it is not recommended to repeat anesthesia using the same halogen-containing drugs, which include "Izufloran".

[46], [47], [48], [49], [50], [51]

Storage conditions

Their properties halogen-containing drugs for anesthesia is stored at a temperature of not more than 30 degrees. And the safety of the drug and others is ensured by the storage of the drug "Isoflurane" in places inaccessible to children with their enormous cognitive abilities.

[52], [53]

Shelf life

The shelf life of the drug, if stored in sealed containers in the original packaging is 5 years.