Anesthesia for children up to 4 years of age. Anesthesia for children: consequences and contraindications
Chapter 19
19.1. Features of anesthesia in children
Peculiarities of anesthesia in children are determined by anatomical and physiological differences between a growing child and an adult organism that has completed its development.
One of the main differences between adults and children is oxygen consumption, which is almost 2 times higher in children than in adults. In the cardiovascular and respiratory systems of the child, there are physiological mechanisms that provide high oxygen consumption.
The cardiovascular system in children is characterized by high lability and great compensatory capabilities. The functional state of the cardiovascular system after hypoxia, blood loss and injury quickly normalizes as soon as the effect of the pathological factor is eliminated. The heart index in children is increased by 30-60% to provide a high oxygen content. The volume of circulating blood is relatively larger than in adults and about twice the rate of blood flow. The neonatal myocardium contains many mitochondria, nuclei, the sarcoplasmic reticulum, and other intracellular organelles to ensure protein synthesis and cell growth. However, not all of these structures are involved in muscle contraction, which makes the myocardium more rigid. The volume of non-contracting sections of the heart muscle is approximately 60%. This circumstance disrupts the diastolic filling of the left ventricle and limits its ability to increase cardiac output due to an increase in stroke volume (the Frank-Starling mechanism). Based on this, stroke volume in children is largely fixed, and the main way to increase cardiac output is to increase heart rate.
Children have high heart rate variability and sinus arrhythmias are common, but serious arrhythmias are very rare. Blood pressure gradually increases with age. A healthy newborn has a systolic blood pressure of 65-70 mmHg. Art., diastolic - 40 mm Hg. Art. At the age of 3 years, it is 100 and 60 mm Hg, respectively. Art. and by the age of 15-16 reaches the usual adult numbers.
Respiratory system. Structural features of the airways create an increased tendency to obstruct them. Children have abundant secretion of mucus, narrowness of the nasal passages, a large tongue, often adenoids and hypertrophied tonsils. In children, a small functional capacity of the lungs, which, combined with a high standing diaphragm and a small number of alveoli, leads to low reserves of respiratory volume, therefore, an increase in minute respiratory volume occurs only due to tachypnea. All these factors lead to a decrease in the reserve capacity of the lungs, and therefore, even in a well-oxygenated child with obstruction of the upper respiratory tract, cyanosis develops in a few seconds.
Due to the high location of the larynx, the large and wide epiglottis when intubating the trachea, it is better to use a straight blade that raises the epiglottis. The size of the endotracheal tube is very important because the mucosa in children is very vulnerable, and a tube that is too large in diameter will contribute to post-intubation edema with tracheal obstruction after extubation. In children under 10 years of age, an uncuffed tube should be used with a mandatory small gas flow leakage around the tube during ventilation.
Water-electrolyte metabolism in young children is characterized by significant variability, which is associated with daily changes in body weight, cell and tissue structure.
The predominance of the percentage of water to body weight, the change in the ratio between the extracellular and intracellular fluid, the increased content of chlorine in the extracellular sector create the preconditions for early disruption of hydroionic balance in children of the first years of life. Kidney function is underdeveloped, as a result of which children cannot tolerate large water loads and efficiently remove electrolytes.
Extracellular fluid makes up approximately 40% of the body weight of newborns, compared with 18-20% in adults. The consequence of increased neonatal metabolism is an intense circulation of extracellular water, so interruption in normal fluid intake leads to rapid dehydration, which dictates the importance of an intraoperative fluid regimen. Maintenance infusion for non-blood loss, less traumatic operations is calculated on an hourly basis depending on body weight: 4 ml/kg for the first 10 kg, plus 2 ml/kg for the second 10 kg and 1 ml/kg for every kg over 20 kg. The maintenance infusion replaces the fluid normally consumed by the child. After most minor and medium-sized operations, children begin to drink quite quickly and replenish the fluid deficiency on their own.
Thermoregulation in children is imperfect. A change in body temperature in the direction of both hypothermia and hyperthermia causes pronounced disturbances in vital activity. A decrease in body temperature by 0.5-0.7 ° C leads to impaired oxygen return by tissues, deterioration of microcirculation and metabolic acidosis, resulting in gross changes in the cardiovascular system, liver and kidney function. In children who have undergone hypothermia during anesthesia, there is a delayed awakening and prolonged inhibition of reflexes.
In a hot operating room, children can become overheated, especially if they had a high temperature before surgery. Hyperthermia can be provoked by the administration of atropine and inhalation of ether. An increase in temperature, if it is not related to the nature of the disease for which surgery is performed, is a contraindication to surgery. Hyperthermic reaction should not be identified with the syndrome of malignant, or "pale", hyperthermia. The air temperature in the operating room must be constantly monitored using a conventional thermometer.
The dosage of drugs for a child of the appropriate age is part of the adult dose. It is convenient for an anesthesiologist working with the "adult" category of patients to be guided by the following rule: children 1 month old. - 1/10 of the adult dose, from 1 to 6 months. – 1/5, from 6 months. up to 1 year - 1/4, from 1 year to 3 years - 1/3, from 3 to 7 years -1/2 and from 7 to 12 years - 2/3 of the adult dose.
Preoperative preparation in children, as in adults, should be aimed at assessing the functional state, identifying and predicting possible disorders with their subsequent correction. Psychological preparation for the operation is very important (it is not necessary for children under 5 years of age).
Premedication in children is performed not only to create mental peace in the ward before the operation, but also when transporting the child to the operating room, as well as placing him on the operating table. From these positions, diazepam, midazolam and ketamine can be used. The latter is the most widely used. Ketamine is administered intramuscularly at a dose of 2.5-3.0 mg/kg with atropine, droperidol or diazepam at appropriate dosages. Such a combination of drugs provides not only premedication, but also partial induction of anesthesia, since the children enter the operating room almost in a state of narcotic sleep.
In recent years, positive experience with the use of midazolam has been accumulated. The drug is more manageable than diazepam. It is used for premedication in children sometimes as the only remedy. Can be used in transnasal drops, by mouth as a syrup, or intramuscularly.
Introduction to anesthesia in children is often carried out by the inhalation method of halothane and nitrous oxide. If the premedication is effective, then the mask of the anesthesia machine is gradually brought closer to the face of the sleeping child, first supplying oxygen, after which a mixture of nitrous oxide and oxygen in a ratio of 2: 1. After the mask is applied to the face, inhalation of halothane is started at a minimum concentration. Gradually, as you get used to it, increase it to 1.5-2.0 vol.%. It is convenient to use an intramuscular injection of ketamine at a dose of 8-10 mg/kg of body weight for the introduction into anesthesia. The use of such a dosage provides not only premedication, but also the introduction into anesthesia. The intravenous method of introducing anesthesia is used to a limited extent, due to the extremely negative reaction of the child to venipuncture and the environment. This path is justified only in cases where the patient has a vein catheterized in advance.
Maintenance of anesthesia. When performing minor surgical operations, one-component anesthesia with non-inhalation anesthetics (ketamine, propofol) or inhalation anesthetics (a mixture of oxygen and nitrous oxide with the addition of halothane) is fully justified.
Indications for endotracheal anesthesia in children are almost the same as in adults. Long-term surgical interventions are performed under conditions of combined anesthesia using drugs for neuroleptanalgesia, nitrous oxide, halothane and ketamine.
As a component of combined anesthesia, various types of regional anesthesia should be used. Endotracheal anesthesia, in combination with epidural anesthesia, allows not only to provide effective analgesia during surgery, but also to provide pain relief in the postoperative period. This technique has undoubted advantages, but it should be used only by experienced anesthesiologists.
Muscle relaxants in pediatric practice are used for the same indications as in adults. However, it should be remembered that the frequency of their use is usually less than in adults, since the initially low muscle tone in children against the background of mechanical ventilation is further reduced. In addition, depression of the respiratory center under the influence of general anesthetics and analgesics in children is more pronounced. Usually it is enough for a child to inject muscle relaxants 1-2 times. Subsequently, throughout the operation, the need for total curarization often no longer arises. The dose of depolarizing muscle relaxants before tracheal intubation is 2-3 mg / kg of body weight, and the repeated dose is 1/2 - 1/3 of the initial one. There are no unequivocal recommendations regarding the use of antidepolarizing muscle relaxants. Most authors treat the use of these drugs with caution, or use antidepolarizing muscle relaxants for precurarization.
Children usually recover faster from anesthesia and surgery than adults. It should be remembered about the possibility of occurrence in the first hours after extubation of laryngotracheitis or edema of the subglottic space. Laryngotracheobronchitis is manifested by a rough cough, and in a more severe form - shortness of breath, indrawing of the sternum and inadequate ventilation. In mild cases, it is only necessary to continue observation and provide the child with humidified oxygen inhalation. In more severe situations, adrenaline is delivered through a nebulizer. Sometimes glucocorticoids can be effective. If all the above measures are ineffective, there is an increase in gas exchange disorders, it is necessary to reintubate the trachea with a small tube. This complication can be avoided by pre-selecting the optimal size of the endotracheal tube for anesthesia.
Surgery in children and anesthesia has its own characteristics. This is due to the child's AFO, as well as the imperfection of the child's immune system.
The child's cardiovascular system is resistant to the effects that occur during surgery, but the regulation of vascular tone is not perfect, which leads to the development of collapse.
The blood volume of a child at birth is 85 ml/kg (in adults: M - 70 ml/kg, F - 65 ml/kg). In cases of blood loss in a child, it is necessary to carry out blood transfusion therapy - “drop by drop”, since 50 ml of a child’s blood corresponds to 1 liter of an adult’s blood.
The pulse in children is frequent, tachycardia. BP is low and is determined by the Molchanov formula:
BP = 80 + age × 2.
Diastolic pressure is 1/3 or 1/2 systolic.
The speed of blood flow in children is 2 times faster than in adults, so the tendency to edema of the mucous membranes, skin, brain is much faster.
The heart muscle in a child is mainly supplied with blood from the left coronary artery, has the same properties as in adults (excitability, conductivity, contractility, automatism). The pacemaker is the sinus node. For children, the physiological feature is sinus tachyarrhythmia. On exhalation, the pulse quickens, and on inspiration it slows down, respiratory arrhythmia occurs. All other rhythm disturbances are pathological.
Peripheral BP is maintained by heart rate rather than stroke volume as in adults. The volume of non-contracting muscle mass of the heart in a child is 60% (up to 14 years), in an adult - 15-20%.
Bradycardia is not typical for children. Given this fact, metacin is introduced into premedication instead of atropine, which does not increase heart rate.
The respiratory system is extremely unstable compared to the cardiovascular system.
Big head
short neck
big tongue
narrow nasal passages
High anterior larynx
"U" - figurative form of the epiglottis
A small glottis - all this makes intubation in children difficult, therefore, when choosing anesthesia in children, they proceed from the volume of surgical intervention. 1st place is occupied by non-inhalation anesthesia, 2nd - mask, 3rd in extreme cases - endotracheal.
A laryngoscope in pediatrics is used with a straight blade, and an endotracheal tube without a cuff is better than a Cole tube. The length of the child's trachea is 4 cm. [diameter is the same]
The diaphragm is high. The tidal volume is severely limited due to the horizontal ribs and the relatively large abdomen. Therefore, anesthesia and respiratory equipment should be selected individually and carried out only in a special nursery, where there should be the least resistance to inhalation, and for small children a pendulum system should be used.
Oxygen consumption in children is 2 times greater than in adults. Per 1 kg is 6 ml / min, and in adults 3 ml / min. Due to the narrowness of the choanae, the presence of adenoids, hypertrophied tonsils, an abundance of mucus, hypersecretion of the glands of the oral cavity and the tracheobronchial tree, every intubation is thought out to the smallest detail. The length of the endotracheal tube is calculated by the formula: from the earlobe to the wing of the nose × 2. The endotracheal tube is lubricated only with hormonal ointment.
Bifurcation of the trachea at the level of the 2nd rib. The continuation of the trachea is the right bronchus, and the left one is at an angle. The respiratory center is located in the medulla oblongata, but it is more sensitive to narcotic analgesics. The type of breathing is mixed.
The nervous system of a child is immature and very sensitive to external stimuli. Children are prone to generalized reactions, the child reacts violently even to touch. It is difficult to establish psychological contact with a child, so it is advisable to give children general anesthesia, rather than using local or regional anesthesia. Children often undergo basic anesthesia and it should be gentle and exclude painful manipulations.
The immaturity of the nervous system is manifested by apnea. Anesthetics easily depress the respiratory center and change its susceptibility to carbon dioxide. Therefore, children develop hypoxia and hypercapnia faster than adults. Children are more sensitive to muscle relaxants, especially to non-depolarizing muscle relaxants, but both are used if necessary.
The child feels pain from the first minute of life and reacts with crying and movements, so if any additional manipulations are necessary in the postoperative period, then they are in no hurry to wake up.
Thermoregulation in a child is unstable. Body temperature depends on the ambient temperature. This is explained:
1) Small fat layer
2) Underdeveloped muscle mass
3) Immaturity of the nervous system
It must be remembered that the surface of the child's head is a significant part of the total surface area of the body. If you cool the child's head, then this will lead to a general cooling, that is, the temperature of the child's body will decrease. Usually, full-term babies cope with minor changes in the external environment on their own, while premature and debilitated babies do not. Therefore, children should be in incubators, the temperature in which is ~ 28 0 C. Overheating of the child is just as dangerous as cooling. Overheating is possible due to:
1) Underdevelopment of sweat glands
2) Immaturity of the nervous system
The constancy of temperature and humidity in the inhaled air-gas or gas-narcotic mixture is very important. For young children, heated operating tables are used, and the constancy of temperature and humidity of the gas-narcotic mixture is achieved using an electric ventilometer, which is installed on the inhalation line.
An increase or decrease in temperature by 1 0 C leads the child to the development of acidosis.
In children under 14 years old, thymus syndrome (immunodeficiency syndrome) occurs - an inadequate response of the body to an irritant. Therefore, in children under 14 years of age, prednisone is introduced into premedication. Allergic reactions in children are always violent and the use of prednisolone (25 mg) is always justified.
Of great importance in the preoperative preparation of children is the completeness of the examination with a mandatory review by an otorhinolaryngologist.
Drug preparation up to 14 years of age is not carried out the day before, and they try to carry out premedication in a painless way (skin application, chewing sweets). Premedication is always METOCIN, and Promedol is rarely used, replacing it with Diphenhydramine.
Venepuncture is performed either after local anesthesia using the application method, or during mask anesthesia.
Hypnotics choose the least toxic, and more often use the inhalation method.
Basic anesthesia N 2 O + O 2 + traces of halothane or azeotropic mixture.
Then the I/O system is connected.
Short-acting relaxants (ditilin) are introduced.
Intubation. Children are intubated through the lower nasal passage. The time spent on intubation is 2 times less (~ 7 sec). Must have Megill forceps or forceps.
The anesthetic should be mild and not irritate the upper respiratory tract.
IVL is carried out in the mode of moderate hyperventilation, and if the pendulum system, then double the volume.
Anesthesia-respiratory equipment used in pediatrics must meet certain requirements:
ü Have minimal inspiratory resistance
ü Have minimal dead space
ü The gas-narcotic mixture must be supplied at a constant temperature and humidity
ü The operating table must be heated
ü Oxygen in the inhaled mixture must be at least 60%, and the circuit is semi-open or pendulum
Hypoxia and hypercapnia, which can develop during anesthesia very quickly leads (especially in young children) to cerebral edema. Therefore, all anesthesia in pediatric practice is carried out only in the presence of a doctor and careful monitoring in accordance with the Harvard monitoring standard.
Infusion therapy is calculated in children taking into account the initial state of the child, preoperative preparation, intraoperative losses and postoperative needs. With blood loss, infusion therapy "drop by drop". For children under one year old, infusion therapy includes colloid solutions with a minimum salt content, since children have functional insufficiency of the renal parenchyma. For 1 minute should be 1 ml of urine. General anesthesia affects the kidneys in direct proportion, that is, the deeper the anesthesia, the more the functional state of the kidneys is inhibited.
In the postoperative period, especially in children under 5 years of age, if the volume of surgical intervention allows, after 3 hours the child is transferred to enteral nutrition, since children are prone to hypoglycemia, and their blood sugar quickly decreases up to 5-6 hours.
The daily fluid requirement for a child up to 10 kg is 100 ml / kg
10-20 kg - 150 ml/kg
the calculation takes into account the disease, age and physiological losses.
The need for electrolytes (Na +, K +) - 3 mmol / kg per day
P.S.: In weakened children, the dose of relaxants is reduced by half from the due one. Anesthesia is carried out at stage III: 1st and 2nd levels. The younger the child, the faster the transition from the 1st level to the 2nd. The breathing bag is designed to control breathing. After any anesthesia, the child is transported to the ward only with a doctor and an Ambu bag.
When introducing and withdrawing from anesthesia in pediatric practice, more attention is paid. There is no need to rush to wake up.
The ventilation capabilities of a child's lungs can be significantly reduced by the surgeon's hands or instruments (just press down on the chest).
Features of the use of vasoconstrictors
anesthesia in children
In children under 5 years of age, a vasoconstrictor is not added to the anesthetic solution, because. at this age, the tone of the sympathetic nervous system predominates, as a result of which adrenaline can cause an increase in heart rate, an increase in blood pressure, and heart rhythm disturbance. Under the influence of adrenaline, a sharp narrowing of the vessels of the abdominal cavity and skin is possible, which causes trembling, severe pallor, sticky cold sweat, fainting. For children over 5 years old, an adrenaline solution is added at a dilution of 1: 100,000 (1 drop per 10 ml of the anesthetic solution, but not more than 5 drops for the entire amount of the solution if it is administered simultaneously). Dosing should be carried out taking into account the body weight and age of the child.
At the same time, vasoconstrictors themselves can cause the development of a toxic reaction, the characteristic features of which are anxiety, tachycardia, hypertension, tremor, and headache. Adverse reactions that occur in response to the introduction of vasoconstrictors in dental practice are most often associated with technical errors, excess concentration of the injected solution, repeated administration of a vasoconstrictor with a local anesthetic into the vascular bed. In this regard, the main preventive measure is the use of standard ampoule solutions, in which the concentration of vasoconstrictors is in strict accordance with the standard.
1. During the injection, the child should be distracted.
2. Superficial anesthesia on the mucosal area is required.
3. It should be explained to the child that the pain from the injection occurs due to the pressure of the anesthetic solution on the tissues of the oral cavity.
4. During injection anesthesia, the doctor must maintain contact with the child, monitor the color of the skin, pulse and breathing.
5. The total dose of anesthetic in children should always be less than in adults.
6. The best time to treat children is in the morning, as overworked children are difficult to persuade and do not make contact with a doctor.
In young children, there is only a very small amount of loose fiber in the groove between the alveolar and palatine processes of the upper jaw along the palatine neurovascular bundle. There is no fiber in the anterior part of the palate from the level of the incisive foramen, so it is practically impossible to inject an anesthetic under the mucosa, with the exception of the zone of the incisive papilla, which is the most reflexogenic zone.
Conduction anesthesia in the upper jaw in children is practically not used for tooth extraction, because. the cortical plate on the upper jaw in childhood is very thin, due to which the anesthetic easily diffuses through it, which ensures a good anesthetic effect. Most often, conductive anesthesia in childhood during tooth extraction is used to anesthetize the removal of molars (temporary and permanent) and premolars in the lower jaw.
A feature of the setting of conduction anesthesia in a child is that it is not required to accurately bring the end of the injection needle to the hole from which the neurovascular bundle emerges, because. the abundance of fiber in the pterygo-mandibular space ensures good diffusion of the anesthetic solution to the nerve trunks.
Location mandibular foramen in children varies with age:
1. From 9 months up to 1.5 years- 5 mm below the top of the alveolar process.
2. At 3.5–4 years- 1 mm below the chewing surface of the teeth.
3. At 6–9 years old- 6 mm above the chewing surface of the teeth.
4. By the age of 12 due to the predominant increase in the size of the alveolar process, the mandibular foramen "descends" to 3 mm above the chewing surface of the lower molars. The hole diameter increases from 3.3 mm to 4.5 mm.
Summarizing the above, we can conclude that in children under 5 years of age, the injection zone is located just below the chewing surface of the teeth of the lower jaw, and in children older than 5 years, it is 3–5 mm above the chewing surface of the teeth.
chin hole in young children, it is located in the region of temporary canines, and at 4–6 years old, it is located near the tops of the roots of the second temporary molars.
Great palatine foramen in children, located at the level of the distal surface of the crown V êV, and subsequently it seems to be shifted backwards and is located sequentially at the level of the distal surface, first of the first permanent, then the second permanent molar
At incisal hole, taking into account the reflexogenicity of the zone, an injection is made not into the center of the incisive papilla, but from the side at its base, followed by the transfer of the syringe to the middle position. Promotion of the syringe deeper into the incisive canal by more than 5 mm is unacceptable due to the possible penetration of the needle into the nasal cavity.
infraorbital foramen located under the tops of the roots of the first temporary molars.
Features of anesthesia
in old age
In the elderly, local anesthesia has a number of features due to age-related changes in the body. In elderly and senile patients, drugs are absorbed more slowly than in young patients. Therefore, it is recommended to first enter about half the dose, and then gradually increase it, guided by the rule: it is easier and safer to administer an additional dose if necessary than to deal with an overdose of the drug.
Elderly people are more sensitive to local anesthesia, often they experience intoxication, collapse, lowering blood pressure, hypertensive crisis. Therefore, the dose of the anesthetic agent should be less than usual (it is more expedient to use amide anesthetics), and the anesthetic agent should be administered very slowly.
The choice of anesthesia method should be based on a deep analysis of the general condition of the patient, taking into account the scope of the intervention. Gerontostomatological patients react sharply to any injury, so it is advisable to perform application anesthesia of the injection site.
Infiltration anesthesia is performed according to the generally accepted method. The anesthetic solution should be administered more slowly so as not to damage the sclerosed vessel walls. At the age of over 70 years, vascular damage is pronounced (thickening of the walls, sclerosis, a sharp narrowing of the lumen of the vessels up to complete obliteration). In parallel with this, arteriovenous anastomoses are intensively developing according to the type of trailing arteries. Due to the upcoming difficulty in the movement of blood through the veins, the latter increase in size to facilitate venous circulation, and their number increases. Sometimes whole plexuses are formed at the site of several veins and anatomical prerequisites appear for the occurrence of hematomas in case of trauma to the vessels with an injection needle.
Since in elderly and senile people the outer cortical plates of the jaws are more dense, the bone tubules are narrowed, the bone is sclerotic, the penetration of the anesthetic to the nerve endings is difficult. In this regard, infiltration anesthesia in this contingent is not effective enough and it is preferable to use conduction anesthesia.
One of the difficulties in conducting anesthesia in elderly and senile patients is the reduction or complete absence of landmarks on the jaws with pronounced atrophy. In these cases, attention should be paid to the width of the lower jaw branch, the degree of its atrophy. In some cases, the thickness of the walls is determined from the radiograph. In patients without teeth, it is recommended to perform anesthesia by extraoral methods.
With tuberal anesthesia performed intra- and extra-orally in the case of an edentulous upper jaw, the zygomatic-alveolar ridge serves as the main reference point. It is necessary to make an injection into its posterior surface and advance the needle strictly along the bone 2–2.5 cm posteriorly, up and inward from the injection site. An anesthetic solution should be released prior to administration. The advantage of extraoral anesthesia over intraoral anesthesia is that with this method the needle can be directed almost perpendicular to the sagittal plane, which avoids injury to blood vessels and the formation of hematomas.
Since the zygomatic-alveolar ridge is easily palpable in senile patients due to pronounced atrophic processes and a poorly developed buccal fat pad with the extraoral method, it is not difficult to perform extraoral anesthesia. And yet, because of the proximity to the tubercle of the upper jaw of the pterygoid venous plexus, there is a danger of damage to it, especially in the elderly. The wound is accompanied by hemorrhage with the formation of hematomas, which can become infected and suppurate. This is especially dangerous due to the presence of a close connection with the cavernous sinus of the dura mater.
To anesthetize the area at the infraorbital foramen, anesthesia is best performed extraorally, since there are no intraoral landmarks (teeth) on the jaws. The failure of the needle to enter the hole can be explained by the atypical direction of the canal and anomalies in the number of holes.
In older people using removable dentures, due to the influence of plastics and pressure of the prosthesis, the color of the mucous membrane of the hard palate is also dark red. In such cases, when determining the boundary of the hard and soft palate, line A serves as a guide.
In case of atrophy of the incisive papilla during incisal anesthesia, an injection is performed 0.5 cm distal to the alveolar eminence along the midline, which can be determined by the median suture of the palate.
Difficulties in performing mandibular anesthesia in edentulous individuals are associated with atrophy of the alveolar process, pterygo-maxillary folds, retromolar fossa, anterior margin of the internal oblique line, and hypertrophy of the tongue. Lingula, sulcus mylohyoideus and f. mandibulae form a functionally integrated whole. The effect is achieved when the solution penetrates above the lingula and lateral to the ligamentum shenomandibulare. With a wide-open mouth, the pterygo-mandibular fold can serve as a guide. If you mentally divide it in half and make an injection in the middle, then by directing the syringe from the opposite side (level of the 5th tooth), you can get the needle into the bone above f. mandibulae by 1 cm (the syringe must be in a horizontal position). However, sometimes even with impeccably performed mandibular anesthesia, complete anesthesia does not occur. To achieve it, one should not only release the anesthetic solution as the needle advances, but also advance it a sufficient distance (4–5 cm) and pass through the interpterygoid fascia. Then the anesthetic solution will equally wash the lower alveolar and lingual nerves.
When performing mandibular anesthesia according to Bershe-Dubov, it is necessary to take into account the thickness of the subcutaneous base and immerse the needle to a depth of 2–2.5 cm. This type of anesthesia is used to relieve trismus of masticatory muscles, eliminate dislocation of the temporomandibular joint, and anesthetize the mandibular nerve. It must be remembered that in old people, due to the absence of teeth or due to their pathological erasure, the bite is reduced, as a result of which, with the mouth closed, there is no gap between the lower edge of the zygomatic arch and the notch of the lower jaw branch. In this case, the needle cannot pass through the cutting of the branch, since it rests against the branch of the lower jaw. Therefore, it is necessary to ask the patient to slightly open his mouth and only then give an injection. If the injection is made and. the needle rested against the bone, then it should be removed to the subcutaneous base, ask the patient to slightly open his mouth, and then continue to advance the needle.
Conducting chin anesthesia is not difficult, however, it must be remembered that due to atrophy of the alveolar process, the chin hole seems to move towards the hole.
The use of anesthetics with vasoconstrictors in the elderly is limited, due to the high prevalence of general somatic diseases, especially of the cardiovascular system.
Pediatric anesthesiology deals with pre-, intra- and postoperative management of children from birth to adolescence. And although many drugs and techniques are used in both pediatric and adult anesthesiology, there are many differences in the details of their use. Children are anatomically and physiologically different from adults, and the range of diseases to which they are more susceptible also varies. Another feature is the interaction with parents, since often establishing contact with the mother or father of a child is much more difficult than with an adult patient.
A) Preoperative preparation. Due to the incomplete development of the immune system, children are much more susceptible to diseases such as upper respiratory tract infections, pharyngitis, conjunctivitis, and otitis media. Often this is an indication for surgical intervention (for example, with tonsillectomy or bypass of the tympanic cavity).
infections upper respiratory tract, even resolved 2-4 weeks before surgery, can increase the secretion of mucous glands, cause hypoxemia and hyperreactivity of the airways, increase the risk of laryngeal and bronchospasm. The length and duration of symptoms of an upper respiratory tract infection should always be assessed, as it often depends on them whether to postpone the operation, or still carry it out.
Also for anesthesia care planning it is extremely important to clarify the method of delivery (natural delivery or cesarean section, including the reasons for the latter), the date at which the birth occurred, birth weight, hospitalizations in the first months of life (including the neonatal intensive care unit), information about any genetic disorders, malformations of the heart -vascular and respiratory systems. It is also necessary to find out how the patient endured anesthesia in the past, to clarify the burden of the family history regarding anesthesia (especially any signs indicating malignant hyperthermia).
b) Anatomy of the respiratory tract, anesthetic drugs and their metabolism. The shape of the respiratory tract in children is different from that in adults. In adults, the shape is more cylindrical, while in children it is conical, they are located more anteriorly and higher. The cartilages of the larynx and epiglottis are thinner and more prone to collapse. Up to five years, the narrowest point of the respiratory tract in children is the region of the cricoid cartilage (in adults, it is the level of the glottis).
In children fairly large tongue(relative to the oral cavity) and a large occiput, which can cause certain difficulties in giving the child the correct posture for ventilation support. Also, infants have a reduced number of alveoli, reduced lung compliance and increased chest rigidity, which leads to a decrease in the residual functional capacity of the lungs and a decrease in oxygen reserves, which increases the risk of hypoxemia and atelectasis during periods of apnea.
Air exchange in the alveoli in newborns and infants is more intense than in adults; blood flow in blood-rich organs, the heart and brain, is increased. These two facts lead to the fact that when using inhalation drugs, children both quickly sink into anesthesia and quickly get out of it. The minimum alveolar concentration reaches its maximum values in infancy, gradually decreasing with age.
Minute cardiac output in newborns and infants, it primarily depends on heart rate, and not on systolic volume. In children, the left ventricle is relatively rigid and undeveloped, and is unable to significantly increase cardiac output. Heart rate is more important than mean arterial pressure. The heart rate is maximum in newborns, the norm is 120-160 beats per minute. Then the heart rate gradually decreases, reaching 100-120 in infants and 80-100 in children aged 3-5 years.
Thermoregulation in children also has its own characteristics. Newborns have an increased ratio of body surface area to weight, and they also have a reduced amount of adipose tissue. These two factors, combined with the low temperature of the operating room and inhaled drugs, increase the risk of hypothermia. It is important to monitor body temperature, use special heating devices, such as Bair Hugger operating blankets (Arizant, Eden Prairie, MN), and increase the air temperature in the operating room before operations in children. Hypothermia leads to respiratory depression, an increase in the time of recovery from anesthesia, and an increase in pulmonary resistance.
Anesthesiologist one should also remember about the likelihood of developing hyperthermia, a sharp increase in the patient's body temperature. High body temperature is one of the signs of malignant hyperthermia (but it usually develops quite late).
Anxiety due to separation from parents and fear in front of the operating room are quite common. Therefore, many hospitals and outpatient centers allow the presence of parents at the time of anesthesia. Parents should reassure the child, providing him with greater psychological comfort before entering anesthesia. In some cases, sedatives (midazolam 0.5 mg/kg orally 30 minutes before surgery) may be used in the preoperative period. Typically, this premedication is performed on very restless children or children with severe comorbidities (eg, congenital heart disease). Also, restless patients may receive intramuscular injection of ketamine.
V) Administration of anesthesia in a child during surgery. Standard equipment for anesthesia monitoring is used: pulse oximeter, 3 or 5-channel electrocardiograph, tonometer, capnograph, temperature monitor. Introduction to anesthesia is carried out using a mixture of oxygen, nitric oxide and inhalation drug. The most commonly used sevoflurane, it provides the most gentle introduction to anesthesia, because. does not irritate the respiratory tract and does not cause coughing. After the child has fallen asleep, an intravenous catheter is placed and the administration of other necessary drugs (atropine, analgesics, propofol) begins before intubation.
Important use an endotracheal tube correct size, because too large a tube irritates the airways, causing them to swell and increase resistance after extubation. Therefore, uncuffed tubes are most commonly used in children. The leakage volume should be 18-25 cm 2 aq. Art. The size of the tube is determined by the general formula (4+age)/4 or by the length of the distal phalanx of the patient's little finger. After installing the tube, it must be fixed. After that, the patient's eyes are covered, the stomach is decompressed, soft underwear is placed under the child in order to avoid compression of the soft tissues during a long stay in the supine position.
One of the most common muscle relaxants, succinylcholine, is rarely used in children. And although it is a reliable depolarizing muscle relaxant that can quickly stop laryngospasm, in children when it is used, the risk of hyperkalemia, rhabdomyolysis, spasm of the skeletal and masticatory muscles, rhythm disturbances (including bradycardia up to cardiac arrest) sharply increases. Also, its use can provoke malignant hyperthermia.
During maintenance anesthesia intravenous administration of fluids and pharmacological preparations (antibiotics, corticosteroids, antiemetics, narcotic analgesics), the supply of inhalation narcotic drugs is carried out. When administering intravenous fluids, you should be extremely careful, because. the margin of error is extremely small. The amount of fluid administered depends on the weight of the patient. In most cases, the 4-2-1 rule is used: 4 ml/kg/hour for the first 10 kg of weight + 2 ml/kg/hour for the next 10 kg + 1 ml/kg/hour for weights above 20 kg.
At newborns with hypovolemia hypotension develops, but not tachycardia. Also, newborns require the introduction of a glucose solution, while older children can be limited to Ringer's solution or saline. The excess free fluid that accumulates with uncontrolled administration of hypotonic solutions can lead to hyponatremia, convulsions, coma, and death, especially if electrolyte-rich fluids are lost (eg, with prolonged vomiting).
By as the operation approaches towards the end, preparations for the exit from anesthesia and extubation begin. Doses of narcotic analgesics are titrated, the patient is disconnected from the apparatus and transferred to spontaneous breathing, if necessary, muscle relaxant antagonists are used. Intubation is essential to reduce the risk of laryngospasm, either while the patient is still under anesthesia or after regaining consciousness (spasm of the laryngeal muscles can lead to complete airway obstruction). The most dangerous extubation is in the so-called "second stage", when the airways are most sensitive, and the patient has not yet fully recovered from anesthesia. Also, intravenous administration of lidocaine (1 mg / kg) helps to reduce the risk of laryngospasm.
With the development laryngospasm ventilation with a breathing mask usually leads to its rapid relief. With inefficiency, succinylcholine is introduced. After the restoration of airway patency, when the patient begins to breathe on his own, he is transferred to the awakening ward while continuing to monitor oxygen saturation. In the awakening ward, the patient is given maintenance oxygen, and the vital organs are monitored.
Nowadays, more and more children providing outpatient care, although more recently, hospitalization was carried out in almost all cases. Criteria for discharge home are as follows: absence of severe pain syndrome, absence of nausea and vomiting, ability to move, ability to take food and liquids. Premature babies and newborns deserve special attention. Premature babies less than 46 weeks of age from conception have an increased risk of developing central sleep apnea due to the immaturity of the central nervous system. They require monitoring of respiratory function for 12 hours after recovery from anesthesia. With a child aged 46-60 weeks, the necessary control time is at least six hours, in the presence of concomitant diseases from the nervous, respiratory, cardiovascular systems, it should be increased to 12 hours.
G) Pain relief in children. Many drugs used for pain relief in adults can also be used in children. These include fentanyl, morphine, codeine, oxycodone. For oral administration in the postoperative period, oxycodone has been successfully used. Acetaminophen can be used in the form of rectal suppositories (30-40 mg/kg) when administered under anesthesia, it reduces the postoperative need for narcotic analgesics. Codeine can be used either orally (possibly combined with acetaminophen) or rectally, at a dosage of 1 mg/kg every 6 hours (as needed). Approximately 10% of the population lacks the enzyme responsible for converting codeine to morphine, so its effectiveness is not universal.
It is worth remembering this if you achieve adequate pain relief fails with codeine. In contrast, 1-7% of people have a mutation in the DNA encoding citrochrome-450 2d6. In this group of patients, there is a higher concentration of morphine in the blood plasma, which requires a downward adjustment of the dosage, especially before adenotonsillectomy for respiratory failure.
e) Eating before surgery. Diet recommendations (nil per os, “nothing by mouth”) differ between adults and children. As a rule, to reduce the risk of aspiration and complications from the lungs, eating before surgery is prohibited. Newborns and children under three years of age, due to the peculiarities of physiology, are more difficult to tolerate dehydration, so the "nothing by mouth" regimen is observed for less time to avoid the risk of dehydration. Infants may be given clean drinking water, pedialitis (Abbott Laboratories, Columbus, OH) or apple juice two hours before surgery to speed gastric emptying, reduce gastric residual volume, and reduce the risk of aspiration.
human breast milk also quickly evacuated from the stomach into the intestines, they can be fed four hours before surgery. In children under 36 months, animal milk and infant formula can be taken up to six hours before surgery. Children aged 36 months and older should not eat any food or fatty liquids (such as milk) for at least eight hours, and can drink small amounts of clean water no later than two hours before surgery.
e) Complications of anesthesia in a child. Most of the complications in pediatric practice develop from the respiratory organs, the most common is laryngospasm. Conditions that develop in the perioperative period are bronchospasm, postintubation croup, and postoperative pulmonary edema. Bronchospasm develops as a result of constriction of the muscles of the bronchi and bronchioles. Patients with easily irritable, hypersensitive airways, bronchial asthma, and children who have had an upper respiratory tract infection shortly before surgery are most at risk. Clinically, bronchospasm is manifested by wheezing, hypoxemia, and the inability to adequately ventilate the patient, despite the free respiratory tract (because obstruction occurs at the level of the bronchi and large bronchioles).
For cupping inhaled bronchodilators and subcutaneous administration of terbutaline, a β 2 -agonist, are used. If bronchospasm cannot be controlled, isoproterenol may be used; it is also necessary to continue the introduction of inhalation anesthetics with a potential bronchodilator effect.
« Post-intubation croup» affects mainly children from one to four years of age, it is manifested by inspiratory stridor and severe cough, which develop after surgery, accompanied by tracheal intubation. The cause is irritation and swelling caused by the endotracheal tube, most often at the level of the subglottic space. In most cases, the condition resolves on its own. A positive effect is also achieved after intravenous administration of corticosteroids or inhalations with racemic epinephrine. The risk of post-intubation croup increases with the use of a tube that is too large in diameter, with repeated attempts at intubation with trauma to the mucous membranes, repeated manipulations with the endotracheal tube, with prolonged operations, and with some diseases of the head and neck.
Postoperative pulmonary edema(Negative Pressure Pulmonary Edema) is a life-threatening condition caused by airway obstruction. It usually develops during induction or during recovery from anesthesia in patients who often do not have any pathology from the cardiovascular or respiratory systems. In individuals who have had an episode of airway obstruction in the past, requiring medical intervention, the risk of postoperative edema increases to 10-15%.
risk factors are: the presence of diseases of the respiratory tract, difficulty in intubation, as well as operations performed on the nasal cavity and larynx. Pulmonary edema develops as a result of creating high negative pressure in the chest in the presence of airway obstruction (most often at the level of the glottis with laryngosiasm). As a result of creating a sharply negative pressure in the chest, extracellular fluid is transuded into the alveoli.
The condition is manifested by a drop in saturation oxygen, hypoxemia, retraction of the intercostal spaces. The first sign of edema is the appearance of sputum and a pink foamy secret in the lumen of the respiratory tube. Due to the presence of fluid in the lungs, wheezing and wheezing are heard on auscultation. It is also possible to develop tachycardia or bradycardia, hypertension, profuse sweating. Chest x-ray shows interstitial and alveolar infiltrates, as well as a "white veil" over the lung tissue. Treatments include supplemental oxygen, positive end-expiratory pressure ventilation in intubated patients, and spontaneous ventilation with continuous positive airway pressure in extubated patients.
No evidence received efficiency of routine use diuretics for the relief of postoperative pulmonary edema, but they can help compensate for hypervolemia. The main goal of treatment is to relieve hypoxemia and reduce the amount of fluid in the lungs. The condition usually resolves fairly quickly after a correct diagnosis is made, usually within 24 hours. Early diagnosis and proper treatment are essential to prevent the development of late complications.
and) Anesthesiological allowance for various surgical interventions in children. Tonsillectomy and adenoidectomy. Despite the prevalence of this operation, all children who undergo adenotonsillectomy are at risk of developing complications from the respiratory tract. The operation should be carried out after resolution of all symptoms of viral infections, in case of acute infection or infection of the upper respiratory tract, it is better to postpone the operation. Serious complications of adenotonsillectomy are postoperative bleeding, laryngospasm and postoperative pulmonary edema. Bleeding from the tonsil niches requires immediate medical attention and bleeding control, in most cases in the operating room.
It should always be assumed that patients with bleeding from the oropharynx, the stomach is filled with blood, therefore, to reduce the risk of surgery, the fastest possible induction of anesthesia is required. Then, after intubation and protection of the airway, all contents should be removed from the stomach during extubation to reduce the risk of aspiration during extubation.
Shunting of the tympanic cavity(installation of tympanostomy tubes): inhalation drugs are usually used for anesthesia, maintenance of anesthesia is also provided by the introduction of inhaled drugs through a breathing mask. Depending on the concomitant pathology and the convenience of ventilation of the child through a mask, a decision is made to install an intravenous catheter, through which drugs can be administered later.
Delirium awakening: quite common in childhood, is a side effect of sevoflurane. Studies have shown that intravenous administration of propofol after discontinuation of sevoflurane reduces the risk of awakening delirium.
h) Key Points of Pediatric Anesthesia:
The normal heart rate in newborns is 120-160 beats / min, in infants 100-120 beats / min, in children 3-5 years old 80-100 beats / min.
The choice of the size of the endotracheal tube is carried out according to the formula (4 + age) / 4.
The standard regimen for intravenous fluids in children on a "nothing by mouth" diet is calculated as follows: 4 ml/kg/hour for the first 10 kg of weight + 2 ml/kg/hour for the next 10 kg + 1 ml/kg/hour at weighing over 20 kg.
Premature babies less than 46 weeks of age from conception have an increased risk of developing central sleep apnea due to the immaturity of the central nervous system. They require monitoring of respiratory function for 12 hours after recovery from anesthesia. With a child aged 46-60 weeks, the necessary control time is at least 6 hours, in the presence of concomitant diseases from the nervous, respiratory, cardiovascular systems, it should be increased to 12 hours.
With the development of bronchospasm, inhaled bronchodilators and terbutaline subcutaneously are used. With their ineffectiveness, isoproterenol is used intravenously.
