Compliance with the algorithm for choosing a local anesthetic in outpatient dentistry as a prevention of emergency conditions

Advantages and disadvantages

For simple surgical interventions, local anesthesia is indispensable; it has advantages over other types of sensitivity suppression. The drug that is used, an anesthetic solution, acts strictly at the injection site, which helps to avoid severe complications and adverse reactions.

The blockade of pain sensitivity develops on average in 10-15 minutes. The effect lasts for an hour or more, so local anesthesia can reduce pain in the area of ​​the postoperative wound. The patient’s consciousness does not suffer from the action of the local anesthetic, so after the manipulation he can leave the clinic and not be in the ward.

But local anesthesia has its drawbacks. Just a few years ago, it was widely used for operations on superficial tissues and extremities; methods for intravenous administration of drugs with simultaneous application of a tourniquet were developed. Intraosseous anesthesia was widely used. But due to the large number of adverse reactions and complications, these methods began to be used less frequently. And after receiving high-quality drugs for anesthesia, dangerous methods of pain relief were practically abandoned.

The disadvantage of the local method is its limited scope of application. It is effective for anesthesia of mucous membranes, skin and superficial tissues, but is not used for operations on the abdominal and pelvic organs, neck and head.

The infiltration type of local anesthesia cannot be used when operating on malignant tumors due to the possibility of tumor cells entering beyond the wound into other tissues. This increases the risk of developing metastases.

It is impossible to imagine modern dentistry without local anesthesia. Most therapeutic, some orthopedic and almost all surgical interventions are performed after preliminary anesthesia. Articaine-containing local anesthetics, widely used and deservedly considered the most effective and safe, allow many complications to be avoided if the rules of their use are followed correctly [3]. But they also use lidocaine and even procaine (Novocaine), and in maxillofacial surgery - ropivacaine for long-term intra- and postoperative pain relief, so doctors should be well aware of how great the risk of complications is directly associated with the use of local anesthetics (see diagram) .

Let us dwell on systemic toxic reactions to local anesthetics - one of the little-studied complications that can lead to a critical outcome. In contrast to allergic reactions, systemic toxic reactions to local anesthetics are common, especially when high doses of drugs are used. Over the past decades, scientists around the world have carried out a great deal of research and analytical work to study the toxic effect of local anesthetics on the human body and determine the leading signs that distinguish this complication from allergic reactions. The published results of statistical studies convincingly indicate that modern local anesthetic drugs are much less dangerous as allergens (the risk of allergy is 1:2,000,000 injections) and much more likely to cause systemic toxic reactions (the risk is estimated as 1:1000 injections) [12].

Systemic toxic reactions to local anesthetics in maxillofacial surgery and dental practice, in contrast to general surgery, where these drugs are administered in much larger quantities for the purpose of regional anesthesia, are less common, but this complication must be remembered due to the likelihood of a tragic outcome. .

The modern market provides dentists with a wide selection of local anesthetics. When determining the safest drug, it is important to focus primarily on its anesthetic index, duration of effective action and compatibility with other drugs taken by the patient. In table 1 provides information on the maximum doses, duration of action, activity and toxicity of local anesthetics.

Table 1. Anesthetic activity, duration of action, toxicity and maximum permissible dose of various local anesthetics Note. m/a - local anesthetic; m/a+iv/c - local anesthetic with vasoconstrictor; activity - the ratio of the minimum effective dose of novocaine to the minimum effective dose of another drug; toxicity - the ratio of the minimum lethal dose of novocaine to the minimum lethal dose of another drug; anesthetic index is the ratio of the potency of the drug to the relative toxicity of the drug.

The analgesic effect of a local anesthetic is determined by its vasoactivity, lipid solubility, ability to bind to proteins and acidity. Certain adjustments, of course, are made by the somatic status of the patients, as well as the pharmacological interactions that occur in the case of basic drug therapy.

The rate of onset of the analgesic effect, systemic absorption, metabolism and elimination of the local anesthetic determine its physicochemical properties. Thus, the lipid solubility and protein-binding characteristics of a local anesthetic depend on its affinity for the cell membrane of the neuron, which consists of fat (90%) and protein (10%). The higher the fat solubility of the drug, the easier it penetrates the membrane, and therefore the more effective. The better the anesthetic binds to protein, the longer its duration of action. The dissociation constant of the drug determines the rate of onset of the analgesic effect, as well as absorption and elimination.

After injection, part of the anesthetic diffuses onto the neuron membrane; the remaining drug enters the vascular bed. Increased absorption of local anesthetic equates to direct entry into the vessel; This should be especially feared in the acidic environment of the inflammatory focus. The amount of drug absorbed by the vessels depends on vascularization and the amount of blood flow in the anesthetized tissue, as well as the effect of the local anesthetic on the tone of the vascular wall. During infiltration anesthesia, amide anesthetics of medium and long action cause vasodilation, and ropivacaine (naropin), unlike other long-acting drugs (bupivacaine hydrochloride - marcaine), gives a vasoconstrictor effect. If a local anesthetic drug contains a vasoconstrictor, the rate of systemic absorption slows down, but there is a risk of developing tachycardia and atrial fibrillation.

Until recently, it was believed that the degree of systemic toxicity was strictly dependent on the concentration and amount of anesthetic administered. Thus, using lidocaine as an example (Fig. 1), peak levels of anesthetic concentrations in blood plasma were shown, which determine the possible clinical picture of a systemic toxic reaction.

Rice. 1. Dependence of the clinical manifestations of the systemic toxic reaction of lidocaine on the level of its plasma concentration.

However, according to recent publications, the described cases of systemic toxicity of local anesthetics in the practice of general and maxillofacial surgery have suggested that the manifestation of toxic reactions does not always depend on the excessive amount of administered anesthetic; even the doses of drugs recommended for use can cause this complication [6, 16, 18].

Clinically, the systemic toxic effect of local anesthetics is more often manifested by symptoms of central nervous system damage and less often by cardiovascular damage. Due to the variety of conditions that determine the timing and rate of entry of the local anesthetic drug into the vascular bed, the period of development of clinical symptoms of systemic toxicity varies within a fairly wide range - from 1-5 to >60 minutes [10].

Based on the severity of clinical symptoms, systemic toxicity of local anesthetics is divided into 3 degrees [2]. If its degree is mild (minor toxic reactions), the patient’s first complaints are tingling and itching in the area where the anesthetic was administered; these sensations may spread to the lips and tongue. At the same time, tinnitus and a metallic taste in the mouth appear. Breathing and hemodynamics are not impaired, moderate tachycardia may be observed. Since the patient's consciousness is preserved, changes in well-being, as a rule, do not go unnoticed; they cause the patient a certain anxiety, which increases as the symptoms intensify; a feeling of fear is often added. The clinical picture of the development of a toxic reaction may be limited to this; gradually the unpleasant sensations disappear without additional therapeutic measures, and the patient calms down. Most often, mild complications of local anesthesia go unnoticed by the doctor and are not recorded in the medical history. But if the patient’s subjective sensations are accompanied by trembling, twitching of individual muscles, nausea, possibly vomiting, and signs of impaired consciousness, in particular orientation, are noted, it should be understood that the toxic reaction develops and becomes moderately severe. With the maximum severity of clinical manifestations at this stage, the patient’s consciousness becomes confused, speech is impaired, numbness and retardation are characteristic, rapid breathing, decreased blood pressure, bradycardia, motor agitation or convulsions are noted. The appearance of seizures indicates that the systemic toxic reaction is becoming severe. Against the background of convulsions, loss of consciousness, decreased muscle tone, respiratory failure up to apnea, arrhythmias, asystole, relaxation and paralysis of the sphincters can occur. Without providing emergency care to patients in critical condition, including resuscitation measures with mandatory specific elements, death is inevitable.

A systemic toxic reaction to local anesthetics is not necessarily clinically manifested by all of the listed signs; some of them are often observed. An analysis of 93 cases of systemic toxicity of local anesthetics showed that the classic clinical picture developed in only 60% of victims; the predominance of pathological signs of the central nervous system with cardiovascular disorders is observed in 30.3% of cases, and only isolated cardiovascular disorders are described in 9.7% of patients [10].

The frequency of clinical signs indicating the development of a systemic toxic reaction following accidental intravascular administration of a local anesthetic is presented in Fig. 2.

Rice. 2. Frequency of development of clinical signs of toxic effects of local anesthetics [7].

Due to the complexity of conducting studies (it is impossible to perform them on humans!), the mechanism of development of systemic toxicity remains unclear. Today it is known that local anesthetics inhibit the process of oxidative phosphorylation, so the most severe disorders occur in the organs that are least adapted to anaerobic respiration metabolism, and this is primarily the brain and heart [2].

It is believed that the toxic effect on brain cells determines the ability of a local anesthetic to penetrate the blood-brain barrier and block sodium channels of excitable cell membranes, which causes toxic reactions of varying severity. If a convulsive syndrome occurs, the accompanying metabolic acidosis increases the uptake of the drug not only by brain neurons, but also by cardiomyocytes.

Cardiotoxicity is probably primarily determined by the ability of local anesthetics to reversibly bind to the intracellular part of the voltage-gated sodium channels of the cardiomyocyte, preventing them from opening and thereby preventing the generation of an action potential and its propagation along the nerve fiber. And the higher this ability of the anesthetic, the stronger its analgesic effect, but at the same time, the inhibitory effect on the conduction system of the heart [8].

All local anesthetics in high concentrations increase the refractory period of the heart, inhibit the excitability, contractility and conductivity of the myocardium - which means that in doses exceeding permissible concentrations, any of the local anesthetic drugs can cause severe depression of the myocardium. It is important to note that the clinical picture of systemic toxicity caused by lidocaine is manifested primarily by severe pathological reactions from the central nervous system; this allows the doctor to take the necessary measures to save the patient in time. And drugs that are more powerful than lidocaine, even in what is considered an acceptable plasma concentration, can, without causing convulsive manifestations or reducing myocardial contractility, provoke arrhythmias of varying severity [8].

Particular care when performing local anesthesia is required in patients with risk factors for systemic toxicity; these include anemia; hypoproteinemia; chronic heart failure with congestion; impaired liver and kidney function; endocrine and metabolic diseases; pregnancy; old age and young age (children). Compared with adults, young children have a significantly higher ratio of cardiac output and regional blood flow to body weight, and systemic toxic reactions develop more quickly in children due to the rapid increase in peak toxic drug concentrations in plasma. Thus, in a 3-year-old child after topical anesthesia, almost instantaneous absorption of the local anesthetic occurs, and the time for the onset of peak plasma concentration of lidocaine during infiltration anesthesia is comparable to that during its intravenous administration.

Special attention should be paid to the treatment of patients under sedation and general anesthesia using local anesthetics. The literature [10] describes 2 cases of systemic toxicity in infants 6 and 9 months old during uranoplasty under general anesthesia a few minutes after infiltration of local anesthetic (in one case, lidocaine, in the other, articaine). The emerging convulsive syndrome left no doubt about the diagnosis, and assistance was provided in a timely manner. Upon completion of postoperative rehabilitation, patients were discharged from the hospital without neurological deficit. Analysis of other episodes of systemic toxicity occurring during general anesthesia shows that signs of cardiovascular complications are more common because the central nervous system is blocked and early symptoms go unnoticed.

Prevention of toxic effects of local anesthetics

A systemic toxic reaction can be anticipated in cases of planned treatment of patients at risk, when the recommended dose of anesthetics is exceeded, or in non-compliance with anesthesia techniques. But, unfortunately, there is no guaranteed option to prevent this complication [15].

Prevention of systemic toxicity consists of strict adherence to instructions for the use of local anesthetics, correct execution of anesthesia techniques and careful attention to the patient both at the stage of preparation for treatment and during it.

During the initial consultation, be sure to find out complete information about the patient’s health. If you have concomitant somatic diseases, obtain an extract from the medical history indicating the diagnosis and the basic therapy recommended for use. If necessary, conduct additional examination. Before treatment, be sure to determine the patient’s physical condition and record the main parameters (blood pressure, heart rate, respiratory rate) in the medical history. Be sure to inform the patient about the possible risks and obtain his written consent for all planned interventions [3].

When choosing a local anesthetic drug, be sure to choose the least toxic of them, if the situation allows it. The use of long-acting local anesthetics is justified for long-term interventions that require prolonged postoperative pain relief, and only if a full set of resuscitation equipment is available.

Be sure to use the minimum effective dose of local anesthetic, choose a sufficient concentration and do not exceed the required volume of anesthetic. Consider the absorption capacity of the surrounding tissues at the injection site [4].

Before administering the anesthetic, be sure to perform an aspiration test and repeat it if you move the needle along the injection; Do not forget that the results of the aspiration test are false negative in approximately 2% of cases. To increase safety, use ultrasound guidance during injection whenever possible, although its effectiveness has not yet been studied and the risk of intravascular injection of anesthetic remains [5].

Be sure to inject the local anesthetic gradually, slowly (1 ml/min) or fractionally with pauses of 15-30 s. When introducing large portions of anesthetic, the injection interval must be increased to reduce accumulation [4].

Do not interrupt verbal contact with the patient during local anesthesia; be sure to monitor his reaction during manipulation and actively identify complaints - this increases the likelihood that the first subjective signs of a developing systemic toxic reaction will be noticed by you on time [3].

Below are the maximum permissible doses of local anesthetics most used in outpatient dental practice for children and adults (Tables 2-5).

Table 2. Maximum permissible doses of lidocaine 2%

Table 3. Maximum permissible doses of mepivacaine 2%

Table 4. Maximum permissible doses of articaine 4%

Table 5. Maximum permissible doses of mepivacaine 3%

Therapeutic measures for systemic toxic reactions

Until recently, the treatment of systemic toxic disorders caused by local anesthetics included the use of anticonvulsants, ensuring adequate oxygenation of the patient up to tracheal intubation followed by artificial ventilation, infusion therapy with large volumes of blood substitutes with the introduction of glucocorticosteroids and drugs that correct cardiovascular disorders. Carrying out cardiopulmonary-cerebral resuscitation, if necessary, did not include any special features; the complex was performed according to the general protocol [1].

Currently, along with measures to replace the patient’s vital functions, the priority in the treatment of systemic toxicity is to reduce and, if possible, eliminate the systemic effect of local anesthetics [13]. The recommended intravenous administration of lipid solutions, the effectiveness of which has been proven experimentally and clinically [9], allows the symptoms of toxicity to be relieved by binding lipophilic local anesthetics. The plasma concentration of drugs decreases, they are “washed out” (detached along the concentration gradient from the membrane of the neuron and cardiomyocyte) and removed with new portions of lipid. In addition, it is known that lipid-containing solutions are an energy substrate for cardiac mitochondria and this ability is in demand in the case of cardiotoxic reactions. The treatment regimen using Intralipid solution (20%) to eliminate systemic toxic reactions of local anesthetics was called “lipid rescue” [7].

The clinical picture of the severe stage of systemic toxicity of local anesthetics can develop rapidly, so it is very important to correctly assess the first symptoms and begin emergency care in a timely manner. Seizure syndrome remains an absolute indication for the use of benzodiazepines; it is more dangerous to treat it with propofol or ultra-short-acting barbiturates due to their own pronounced cardiodepressive effect. As in previous recommendations, one of the first measures to save the patient is to ensure adequate oxygenation by any available means, including tracheal intubation and mechanical ventilation with 100% oxygen. In case of ineffective blood circulation due to arrhythmia or asystole, resuscitation measures should be started immediately and continued for at least 60 minutes. Since local anesthetics do not cause irreversible changes in the myocardium, with sufficient oxygenation of the brain and the administration of lipid solutions during this time, there is hope for saving the patient. It is extremely important not to rush to stop effective resuscitation measures if systemic toxicity is caused by powerful anesthetics, because they take a long time to “wash out” [6]. When carrying out symptomatic therapy, if necessary, it is necessary to avoid the administration of lipophilic drugs - beta-blockers and calcium channel blockers, abandon vasopressin, use only amiodarone (cordarone) to relieve ventricular arrhythmias, reduce the dosage of epinephrine (adrenaline) to less than 0.1 mcg/day. kg or completely abandon its administration [13].

Literature sources [20] report that in case of a systemic toxic reaction to local anesthetics, rapid administration of large volumes of lipid solutions is not accompanied by significant complications, and their clinical effectiveness against the background of resuscitation measures allows one to avoid residual cardiac disorders and neurological deficits [10, 17].

For “lipid leaching,” any fat emulsion can be used, but Intralipid (20%) has proven itself to be the best [11]. Inactivation of local anesthetics with diprivan (propofol) should not be carried out due to the need for a large amount of the drug to obtain a positive result due to its low lipid content, and this is dangerous since diprivan has a direct cardiodepressive effect [15]. Today, it is recommended to relieve a systemic toxic reaction to local anesthetics with lipids, starting the administration of the drug when the first characteristic complaints or symptoms appear and at the same time being ready to perform a full range of resuscitation measures [6].

In each medical institution, including dental, where local anesthetics are used, it is necessary to have 1 liter of fat emulsion solution (Intralipid 20% - 500 ml or other), syringes for “lipid washing out” with a volume of 50 ml, peripheral intravenous catheters 14-16 G, Infusion systems, copy of the Lipid Rescue protocol [19].

After catheterization of the peripheral vein, the lipid solution must be administered as a bolus (Intralipid 20% - 1.5 ml/kg) using 50 ml syringes, then switch to drip infusion (Intralipid 20%, rate - 0.25 ml/kg/min) and Continue administering the drug at this pace for at least 10 minutes after blood circulation has stabilized. If it is not possible to stabilize blood circulation with this dose of lipid solution, it is necessary to repeat its bolus administration in the same dosage (Intralipid 20% - 1.5 ml/kg) and switch to an accelerated infusion of the drug (Intralipid 20%, rate - 0.5 ml/kg /min). The highest single dose of fat emulsion is acceptable - 10 ml/kg/min.

At the Euroanaesthesia 2010 forum in Helsinki (Finland), the European Board of Anesthesiology, together with the European Society of Anaesthesiology, adopted a declaration on patient safety in anesthesiology. It provides fundamental points that make it possible to prevent and avoid serious complications and prevent danger to patients. In particular, it is stated that all medical institutions that use local anesthetics “... must have protocols and facilities necessary in situations of systemic toxicity...” [14]. The Declaration of Helsinki has been endorsed by the World Health Organization, the World Federation of Societies of Anaesthesiologists and the European Patients Federation. Taking into account its specifics, each country has the right to refine and adapt the protocol for resuscitation using lipid solutions to its own conditions. We consider this task extremely important for our medical community.

The authors declare no conflict of interest.

Types of local anesthesia

Several types of local anesthesia are used in surgical practice, but some of them already have historical significance. The main methods of pain relief are the following:

• superficial anesthesia - pain sensitivity is suppressed after the anesthetic comes into contact with the surface of the tissue, most often used to anesthetize the mucous membranes. The anesthetic solution is applied by lubrication or irrigation, the effect lasts for 10 minutes;
• infiltration anesthesia - anesthesia by impregnation, or infiltration of tissue layers with a local anesthetic. The technique allows you to control the depth and width of the drug injection, depending on the intended incision. The medicine is injected carefully first into the subcutaneous area until the lemon peel effect appears, then the needle is gradually moved inward and an additional dose of the drug is injected;
• anesthesia according to Vishnevsky is an improved version of the infiltration method. A weak anesthetic solution is injected layer by layer under high pressure. A tight creeping infiltrate forms in the tissues. It spreads through the interfascial spaces and disrupts the conduction of impulses along the nerves passing through them. After cutting the wound, the liquid gradually flows out of the wound, so there is no risk of its absorption into the systemic circulation and the development of toxic reactions;
• conduction anesthesia is the essence of the method in anesthetizing a specific area of ​​the body innervated by the nerve trunk. An anesthetic drug is injected into the tissue around the nerve; the technique is used for operations on the limbs;
• spinal anesthesia - the analgesic effect is achieved by injecting an anesthetic drug under the choroid of the spinal cord, the main place of drug administration is the lumbar region, and pain sensitivity in the pelvic organs and lower extremities disappears. But tactile sensitivity does not suffer;
• epidural anesthesia is a type of anesthesia in which a local anesthetic is injected into the space over the dura mater of the spinal cord, and a puncture is also performed in the lumbar region. Sensitivity is lost after 15-20 minutes, but the effect lasts for 3-4 hours. The use of this type of anesthesia allows you to resume activity early after surgery;
• bone anesthesia is a type of anesthesia in which an anesthetic solution is injected into spongy bone. Currently, it is practically not used; previously it was used for operations on the limbs.

Lidocaine (Lidocaine)

2-diethylamine-2′, 6′ acetoxylide hydrochloride. Synonyms: baicaine, dentacaine, xicaine, xylodont, xylocaine8, xylestesin, xylonest, lignocaine, lignospan, lidestin, luan, octocaine, solcaine. Local anesthetic of the amide group, acetanilide derivative. The drug is superior to novocaine in anesthetic activity and duration of action, and is less likely to cause allergic reactions. The drug is compatible with sulfonamides. Lidocaine has antiarrhythmic and sedative effects. The drug affects the conduction system of the heart and suppresses ectopic foci of excitation, which makes it possible to use it as an antiarrhythmic agent.

Indications for use Lidocaine is used for all types of local anesthesia in dental surgery. Contraindications • Hypersensitivity to lidocaine and other components of the drug (adrenaline, sulfates). • Sick sinus syndrome in the elderly. • Atrioventricular block. • Severe bradycardia. • Cardiogenic shock. • Severe liver dysfunction. • History of epileptiform seizures induced by lidocaine. • Pregnancy. • Myasthenia gravis. It should be used with caution in diseases of the nervous system, septicemia, hypertension and in childhood. Cautions : Caution should be used for diseases of the nervous system, septicemia, hypertension, children and elderly patients. When using an ampoule solution of lidocaine, you should check the concentration of the drug, since as an antiarrhythmic drug it can be produced in the form of a 10% solution, the use of which is completely unacceptable for injection anesthesia in dentistry. Side effects Allergic reactions (urticaria, angioedema, anaphylactic shock) to lidocaine are rare. Possible headache, dizziness, drowsiness, anxiety, tinnitus, blurred vision, convulsive twitching, tremor, decreased blood pressure, bradycardia, disorientation. Cases of idiosyncrasy to lidocaine have been described. Method of administration and dosage Lidocaine is used for all types of anesthesia: in the form of a 2% solution for infiltration and conduction anesthesia; in the form of a 10% aerosol solution, 5% gel, 2-5% ointment - for topical anesthesia of the oral mucosa. The drug dilates blood vessels and is used in dentistry in combination with vasoconstrictors.

The maximum total dose for injection is 4.4 mg/kg, but not more than 300 mg. For superficial anesthesia of the mucous membranes, use no more than 2 ml of a 10% lidocaine solution (200 mg).

Preparations for local anesthesia

Local anesthetics are drugs from the group of neurotropic drugs that completely or partially block the flow of signals along nerve fibers from the site of painful manipulation or surgery to the central parts of the nervous system.

The peculiarity of the action of drugs is related to their spectrum of action. They suppress the transmission of signals along myelinated type A nerve fibers, which transmit feelings of pain, smell, and temperature. Tactile sensations are carried out through type B fibers, and anesthetics do not affect them. Therefore, when using local anesthesia, the patient does not feel pain, but feels the touch of the doctor and the surgical instrument.

Local anesthetic drugs are divided into 3 groups depending on the duration of action:

• short-acting - the effect lasts 30-50 minutes, these include Novocain;
• average duration - up to 90 minutes, these are drugs Lidocaine, Trimecaine, Ultracaine;
• long-acting – the effect lasts more than 90 minutes, typical for Bupivacaine.

Local anesthetic drugs affect the electrochemical processes of ion exchange in nerve endings. Medicines work effectively in an alkaline environment and tissues rich in lipids, which include nerves. But the analgesic effect decreases with severe tissue inflammation, which is associated with a transition of pH to the acidic side.

The effect of local anesthetics is enhanced by drugs that affect vascular tone. Therefore, they are often combined with adrenaline to prolong the effect. This allows you to reduce the dose of pain medication and avoid toxic reactions.

Trimecain (Trimecainum)

Synonyms: 2,4,6 - diethylaminoacetic acid anilide trimethylacetylate hydrochloride. Trimecaine is similar in pharmacological action to lidocaine. Its anesthetic activity is 2-3 times higher than novocaine, it acts faster and longer, and does not irritate tissues. Trimecaine is somewhat more toxic than novocaine, especially in higher concentrations. The drug dilates blood vessels and is used in dental practice with vasoconstrictors. Indications for use • Infiltration anesthesia for interventions on the upper jaw. • Conduction anesthesia. • Superficial anesthesia of the oral mucosa. In addition, trimecaine, like lidocaine, can be used for ventricular extrasystoles and tachyarrhythmia. Contraindications Contraindications are hypersensitivity to trimecaine, weakness of the sinus node, AV block, severe bradycardia, cardiogenic shock, liver and kidney pathology. Method of application It is used mainly for conduction and infiltration anesthesia, less often for surface anesthesia. Used for injection in the form of a 2% solution, topically - in the form of a 3-5% ointment. To slow down absorption, add adrenaline to the trimecaine solution (0.1% solution, 1-2 drops per 5-10 ml of trimecaine solution). The maximum total dose for injection is 300 mg. Interaction with other drugs Vasoconstrictors enhance and prolong the effect of trimecaine. Preliminary administration of tranquilizers and sleeping pills increases the effect of trimecaine.

What is operated under local anesthesia in mammology?

The mammary glands are located superficially, they do not have muscles and large nerve trunks. Breast tissue is loosely located; in young women, glandular tissue predominates, which is replaced by fatty tissue with age. Therefore, for numerous manipulations and operations, local anesthesia can be used.

In mammology, anesthesia is used to perform invasive diagnostics, which include breast tissue biopsy. To do this, a local anesthetic is injected with a thin needle into the area of ​​the intended puncture. After 10-15 minutes, the doctor can take breast tissue for examination without fear of causing pain to the patient.

Local infiltration anesthesia in mammology is used for small, minimally invasive operations. A woman can undergo puncture of a breast cyst after preliminary infiltration anesthesia. A similar approach can be used when removing small benign breast tumors.

In men, anesthesia is used during surgery for type 1 gynecomastia, when the size of the gland is still small. Infiltration of tissues increases hydrostatic pressure in them, thanks to which the doctor can easily separate pathological tissues from healthy ones.

Additives to anesthetics:

1) Vasoconstrictors

Vasoconstrictors - added to increase the effectiveness of local anesthesia, as well as to slow down the entry of anesthetics into the bloodstream.

Adrenalin

Adrenaline is used most often. A relatively safe dilution of adrenaline is a concentration of 1:200,000, which can only be achieved in capsule preparations.

Norepinephrine

Norepinephrine is used less frequently as a vasoconstrictor. Norepinephrine, unlike adrenaline, is less dangerous in patients with cardiac pathology (coronary heart disease), but the risk of developing a hypertensive crisis with concomitant hypertension is higher.

Used instead of adrenaline for thyrotoxicosis and diabetes. Contraindicated in glaucoma.

Filipressin (octapressin)

Filipressin is a synthetic drug that does not have a direct effect on the heart. The effect is associated with its direct effect on the smooth muscles of blood vessels. Contraindicated during pregnancy, because may cause myometrial contractions.

Undesirable systemic effects of vasoconstrictors:

• rise in blood pressure,
• tachycardia,
• heart rhythm disturbances,
• angina attacks,
• centralization of blood circulation,
• headache.

Risk group when using vasoconstrictors

: patients with glaucoma, thyrotoxicosis, diabetes mellitus; patients taking drugs rauwolfine, thyroid hormones, tricyclic antidepressants, antidepressants - MAO inhibitors.

2) Preservatives

Parabens

(methylparaben
–
methyl 4-hydroxybenzonate, ethylparaben)

Parahydroxybenzoic acid esters (parabens) are used as preservatives, which have antibacterial and antifungal effects.

It must be remembered that parabens are included in various cosmetics, creams, toothpastes and can provoke contact dermatitis, so there is a real danger of an allergy to the local anesthetic drug.

Para-aminobenzoic acid (PABA), which is a metabolite of novocaine, has a similar structure to parabens, which can cause cross-allergic reactions. Many drugs (sulfonamides, oral antidiabetic drugs, furosemide, etc.) are derivatives of PABA. Therefore, it is not advisable to use drugs containing parabens if you have a drug allergy to the listed medications.

The presence or absence of parabens in the local anesthetic drug is indicated by the manufacturer. Parabens can cause sensitization of the body and anaphylactic shock.

3) Stabilizers

Sulfites

(sodium or potassium disulfite) are used as vasoconstrictor stabilizers. Allergy to sulfites is most common in patients with bronchial asthma (frequency - about 5%), so you should be especially careful when treating such patients. Sulfites cause edema, urticaria, bronchospasm through irritant receptors, nervous and vagal reflexes.

Is it painful to do local infiltration anesthesia?

When performing anesthesia, a standard disposable syringe with a thin needle is used. Whether local anesthesia is painful depends on your general pain threshold. The patient feels the moment of the first puncture of the skin and a slight feeling of fullness when the drug is administered. After the medication begins to act, sensitivity disappears. The doctor checks how effective the injection is by tapping the skin. In response, there is a feeling that the injection site has become woody.

After the end of anesthesia, sensitivity gradually increases, and a slight tingling sensation may appear. If anesthesia was performed for surgery, pain in the wound area begins to bother you, which can be reduced with the help of non-steroidal anti-inflammatory drugs.

Bumecaine

Synonyms: pyromecaine. Indications for use

Pyromecaine is used for superficial anesthesia for stomatitis, gingivitis, glossitis, pulpitis, to anesthetize the injection site and relieve an increased gag reflex. Method of administration and dosage Pyromecaine in dentistry is used only for superficial anesthesia: in the form of a 1% solution to suppress the gag reflex when taking impressions; A 1-2% solution and 5% pyromecaine ointment are used to anesthetize the mucous membranes. An ointment containing 5% pyromecaine and 5% methyluracil, which has an anti-inflammatory effect and stimulates regeneration processes, has been developed for dental practice. When treating inflammatory diseases of the oral cavity, the ointment can be used 1-3 times a day. The dose of ointment should not exceed 1 g.

Contraindications for local anesthesia

Local infiltration anesthesia is a relatively safe method of pain relief. But to reduce risks during and after surgery, it is necessary to take into account contraindications to the use of the method. The main ones are the following:

• allergy to anesthetic - if earlier during dental treatment under local anesthesia an allergy to an anesthetic appeared, then during breast surgery the effect will repeat, and may be more pronounced, up to anaphylactic shock;
• psychomotor agitation and mental illness, reaction to the administration of an anesthetic and the surgical procedure itself can cause unpredictable behavior of the patient;
• during operations on malignant tumors - when infiltration anesthesia does not allow compliance with the ablastic rule;
• during long operations that require the use of microsurgical equipment;
• during interventions on areas of the body with a pronounced vascular network, for example, on the neck.

If local anesthesia is contraindicated, general anesthesia is preferred.

Side effects of painkillers

The negative effects of local anesthesia, although rare, can be quite serious. Some of them develop very quickly, and the dentist must be ready to quickly take action in each of the possible cases.

• Toxic effects: convulsions, drop in blood pressure, arrhythmia, drowsiness. This is the most common group of side effects. They develop when an overdose or a needle accidentally gets into a blood vessel.
• Reactions at the injection site: swelling, inflammation, appearance of ischemic zones. Usually occur when injection technique is violated.
• Effect on the central nervous system: nervousness, dizziness, unreasonable fear, double vision, temperature fluctuations, convulsions, loss of consciousness.
• Effect on the cardiovascular system: decreased heart rate, drop in blood pressure.
• Allergic reactions: itching, discharge from the eyes or nose, Quincke's edema [2].

However, local anesthesia is much safer than general anesthesia, which is used in dentistry only in extreme cases.

The composition of some modern local anesthetics:

• lidocaine (xylocaine) in carpules - contains lidocaine, methylparaben, sodium chloride;
• xylostesin F-forte in carpules – contains lidocaine, norepinephrine hydrochloride, anhydrous carbonic sulfite, carbonic chloride;
• xylocaine MPF – sterile pyrogen-free solution without methylparaben (in carpules);
• xylocaine in vials - contains methylparaben;
• xylocaine MPF with epinephrine - sterile pyrogen-free solution contains xylocaine, epinephrine, sodium metabisulfite, citric acid;
• mepivacaine (mepidont, mevirin, mepivastezin, scan-dicaine, scandonest) – without the addition of vasoconstrictors, sulfites, parabens;
• ultracaine in carpules – contains articaine, adrenaline (0.006), sodium disulfite, methylparaben;
• ultracaine Dc forte – contains articaine, adrenaline (0.012) and sodium disulfite;
• septanest – contains sulfites, EDTA, does not include parabens;
• ubistezin, ubistezin forte (based on articaine, do not contain parabens, but contain sulfites as a preservative).