Features of the structure and function of the respiratory system in children. Functional features of the respiratory system in children

The respiratory movements of the fetus have spinal regulation, that is, they arise automatically due to the excitation of spinal motor neurons innervating the respiratory muscles by a certain gas composition of the blood. The first respiratory movements of a newborn depend on stronger excitation of the same spinal centers, depending on the depletion of blood in oxygen and the accumulation of carbon dioxide. The result of the first extrauterine respiratory movements is an increase in negative pressure in chest cavity, leading, on the one hand, to the expansion of the lungs, and on the other, as a consequence of this to irritation of the vagal receptors. This ensures the rhythmic transmission of nerve impulses along the pulmonary afferent fibers to the retinal formation medulla oblongata.

In a newborn, due to shallow breathing, the lungs do not fully expand during the first respiratory movements, which leads to the so-called physiological atelectasis, which is localized mainly in the posterior-inferior areas of the lung. Even more shallow breathing of premature babies, as well as the existing extreme degree functional insufficiency of the respiratory center leads to the fact that physiological atelectasis becomes especially persistent in them and is fertile ground for the development of pneumonia. Blood pressure in the pulmonary circulation in children is significantly less than in adults, and the distribution of blood in the pulmonary vessels, as in adults, depends on the act of breathing, since when inhaling, the capillaries lengthen, and when exhaling, they shorten. The result of this is a constant redistribution of blood in the lung. In children's lungs, due to frequently occurring emphysema and atelectasis, leading to narrowing of the capillaries in the inter-alveolar septa, a slowdown in blood flow often occurs. And this is one of the most common reasons easily occurring disturbances in gas exchange in the lungs during the development of a pathological process in them.

The systems of pulmonary and bronchial arteries in children form close anastomoses with each other, which is important both in the process of physiological growth and development of the lungs, and in pathological changes as a means of compensating one system for another.

For normal breathing great value has an open airway. This is supported by the correct evacuation function of the bronchi, i.e., their self-cleaning ability and sufficient air permeability. Both of these acts are included in the concepts of compensatory, protective mechanisms in the fight against emerging respiratory infection and are entirely related to the degree of elasticity and ability to expand and contract the bronchi (muscle-elastic properties). In the early childhood Due to the poverty of the respiratory tract with elastic tissue and a number of structural features of the bronchial wall and ciliated epithelium of the respiratory tract, a violation of the evacuation ability of the bronchi with the accumulation of mucus and microbes occurs more easily. In addition, compression of the bronchi by enlarged lymph nodes and chronic processes V lung tissue also contributes to the narrowing and deformation of the bronchial lumen.

External respiration examination has important when determining the degree and form respiratory failure both for diseases of the respiratory system and cardiovascular system, and under medical supervision sports activities at school. All types of external respiration disorders are a consequence of disorders of its nervous regulation and gas exchange.

When determining indicators of external respiration function, simple clinical methods and more complex clinical and laboratory methods, requiring special equipment, can be used. In young children, for obvious reasons, the study of external respiration is usually limited to pneumography, breath counting and, most importantly, clinical observations.

To simple clinical methods include: a) study of respiratory rate and pulse using a stopwatch at rest and during physical activity; b) measuring the size of the chest and its mobility in various phases of breathing (inhalation, exhalation, at rest); c) breath-hold test (Stange-Hench test); d) functional test proposed by the Moscow Institute of Physical Culture; e) spirometry.

Breath-hold test consists of determining the time for which breathing can be completely held. The study is carried out in the inhalation and exhalation phases. Normally, breath holding varies depending on age, ranging from 8 to 12 seconds per preschool age and up to 1 minute in school; after physical activity the delay time is shortened.

When tested by the Moscow Institute of Physical Culture The pulse rate, respiratory rate and blood pressure height are determined before and after physical activity, consisting of 60 jumps in 30 seconds. Normally, all these indicators should return to the original numbers 3-5 minutes after stopping the load. For the purpose of more detailed determination of the state of respiratory and circulatory function, it is recommended to count pulse and respiration. for 3 minutes every 15 seconds, plotting the resulting data on a curve. The shape of the curve (the magnitude of the recovery period) allows us to judge the compensatory reserve of the respiratory and circulatory organs.

It should be taken into account that the results of these tests are significantly influenced by the body’s fitness. Thus, children who regularly engage in physical education, even with illnesses, give better results than untrained children. It is very important to carry out these tests in clinics, as they make it possible to identify the presence of hidden form respiratory failure in chronic pneumonia.

With spirometry, the maximum amount of air exhaled into the spirometer tube after maximum inspiration is determined, i.e., what is called the vital capacity of the lungs.

Spirometry is used during mass examinations of schoolchildren (for example, before sending them to camps and upon returning from camps). The increase in vital capacity of the lungs occurs in parallel with improvement physical condition child - by increasing muscle tone, correcting impaired posture (lordosis, scoliosis, kyphosis) - and therefore, along with other indicators of general physical development(dynamics of weight, height and increase in chest circumference) should be considered an indicator of improvement in general condition.

Studying the vital capacity of the lungs in young children presents significant difficulties, but with a certain amount of training, after the age of 4 years, spirometry can be quite applicable.

In the clinic, when determining indicators of external respiration function, both simple and more complex methods are used.

The spirometer proposed by Hutchinson for studying pulmonary volumes is essentially the beginning of an instrumental study of external respiration. Our domestic scientists have made a great contribution to this area. Of the numerous works in this direction, we point out Dobrynin’s dissertation on determining the vital capacity of the lungs in a number of acute and chronic diseases respiratory system using a spirometer. The work of M. N. Shaternikov on the determination of CO2 in exhaled air by absorbing CO2 with soda alkali was especially important not only for domestic, but also for world physiology. V.V. Pashutin proposed a chamber he designed to determine gas exchange in animals.

Later, when studying external respiration, other indicators began to be determined, which were obtained wide application in the clinic for a wide variety of pathological processes. In conducting pathogenetic therapy, the analysis of external respiration disorders is especially important, as well as indicators of redox processes.

In early childhood, the study of external respiration is naturally limited primarily to clinical observations, breath counting, pneumography and some laboratory tests, since a number of more complex methods require the active participation of the subject himself or special equipment.

To characterize the degree of ventilation of the lungs, lung volumes are usually measured, i.e. vital capacity, etc.

Features of external respiration in young children play a leading role in pathology respiratory disorders, usually accompanying any pathological condition with impaired external respiration. Lability of external respiration in a healthy child is associated with a number of features of individual indicators of external respiration. Firstly, the breathing of a young child is characterized by an increased frequency (the so-called tachypnea (physiological shortness of breath): during the newborn period it ranges from 60 to 48 and subsequently decreases, reaching 30-34 by the end of the first year. Along with this the depth of breathing in the first month of life does not exceed 30 ml and only by the end of the year increases to 70 ml, by 2 years - up to 85 ml, by 5 years - up to 150 ml, by 10 years - up to 230 ml, by 15 years - up to 375 ml.

Thus, the depth of breathing increases at a fairly rapid pace, while its frequency decreases much more slowly.

Pulmonary ventilation, or minute tidal volume, i.e. the amount of air in milliliters passing through the lungs in one minute, varies widely in healthy children.

These figures can only be taken as average, since pulmonary ventilation is affected by all factors, both endogenous (chest shape, fitness) and external (ambient temperature, humidity, atmospheric pressure). Rominge) gives significantly lower figures for pulmonary ventilation, Kempf - much higher.

Pulmonary ventilation is determined using a gas clock: the child breathes for 5 minutes into a special device, first at rest, and then after physical activity. This study requires the active participation of the subject and can be carried out mainly in preschool children and partly school age and, according to our data, only after appropriate training, since in this case the energy of the respiratory act itself is of great importance.

Relative pulmonary ventilation (minute tidal volume per 1 kg of weight) in children of the first six months is maximum and equals on average 410 ml. By the end of the year it decreases to 320 ml, by 2 years - to 240 ml, by 5 years - to 210 ml, by 10 years - to 170 ml and by 15 years - to 110 ml.

Thus, in a young child, reduced absolute pulmonary ventilation is, as it were, compensated by increased relative pulmonary ventilation, which characterizes the intensity of metabolism and the intensity of redox processes in infancy, associated with the energy of growth of organs and tissues.

Vital capacity of the lungs in infancy it is determined approximately, since only exhaled air is measured (when the child cries); therefore, the figures determining the size of vital capacity in infancy range from 100 to 245 ml; in preschool age it is already possible to determine the vital capacity of the lungs by spirometry; by 5 years it is set within 1200 ml, by 10 years - 1800 ml and by 15 years - 3200 ml.

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The respiratory organs in children not only have an absolutely smaller size, but, in addition, they also differ in some incomplete anatomical and histological structure. The child’s nose is relatively small, its cavities are underdeveloped, and the nasal passages are narrow; The lower nasal passage in the first months of life is completely absent or rudimentarily developed. The mucous membrane is tender, rich in blood vessels, the submucosa in the first years of life is poor in cavernous tissue; at 8-9 years old, the cavernous tissue is already quite developed, and there is especially a lot of it during puberty.

The accessory nasal cavities in young children are very poorly developed or even completely absent. The frontal sinus appears only in the 2nd year of life, by 6 years it reaches the size of a pea and is finally formed only by 15 years. The maxillary cavity, although already present in newborns, is very small and only from 2 years of age begins to noticeably increase in volume; approximately the same must be said about sinus ethmoidalis. Sinus sphenoidalis in young children is very small; up to 3 years of age, its contents are easily emptied into the nasal cavity; from the age of 6 years, this cavity begins to rapidly increase. Due to the poor development of the paranasal cavities in young children, inflammatory processes from the nasal mucosa very rarely spread to these cavities.

The nasolacrimal duct is short, its external opening is located close to the corner of the eyelids, the valves are underdeveloped, which makes it very easy for infection to enter the conjunctival sac from the nose.

The pharynx in children is relatively narrow and has a more vertical direction. Waldeyer's ring in newborns is poorly developed; pharyngeal tonsils are not noticeable when examining the pharynx and become visible only by the end of the 1st year of life; in the following years, on the contrary, the accumulations of lymphoid tissue and tonsils hypertrophy somewhat, reaching maximum growth most often between 5 and 10 years. During puberty, the tonsils begin to undergo reverse development, and after puberty it is relatively rare to see their hypertrophy. Enlargements of the adenoids are most pronounced in children with exudative and lymphatic diathesis; they especially often experience nasal breathing disorders, chronic catarrhal conditions of the nasopharynx, and sleep disturbances.

The larynx in children of the earliest age has a funnel-shaped shape, later - cylindrical; it is located slightly higher than in adults; its lower end in newborns is at the level of the IV cervical vertebra (in adults, 1-12 vertebrae lower). The most vigorous growth of the transverse and anteroposterior dimensions of the larynx is observed in the 1st year of life and at the age of 14-16 years; With age, the funnel-shaped shape of the larynx gradually approaches cylindrical. The larynx in young children is relatively longer than in adults.

The cartilage of the larynx in children is delicate, very pliable, the epiglottis is relatively narrow until 12-13 years of age and in infants it can be easily seen even with a routine examination of the pharynx.

Gender differences in the larynx in boys and girls begin to emerge only after 3 years, when the angle between the plates thyroid cartilage in boys it becomes more acute. From the age of 10, boys already have quite clearly identified features characteristic of the male larynx.

The indicated anatomical and histological features of the larynx explain the mild onset of stenotic phenomena in children, even with relatively moderate inflammatory phenomena. Hoarseness, often observed in young children after a cry, usually does not depend on inflammatory phenomena, but on the lethargy of the easily fatigued muscles of the glottis.

The trachea in newborns has a length of about 4 cm, by the age of 14-15 it reaches approximately 7 cm, and in adults it is 12 cm. In children of the first months of life, it has a somewhat funnel-shaped shape and is located higher in them than in adults; in newborns, the upper end of the trachea is at the level of the IV cervical vertebra, in adults - at the level of VII.

Tracheal bifurcation in newborns corresponds to YYY-YV thoracic vertebrae, in children 5 years old - IV--V and 12 year olds - V--VI vertebrae.

The growth of the trachea is approximately parallel to the growth of the trunk; There is an almost constant relationship between the width of the trachea and the circumference of the chest at all ages. The cross section of the trachea in children in the first months of life resembles an ellipse, in subsequent ages it resembles a circle.

The tracheal mucosa is tender, rich in blood vessels and relatively dry due to insufficient secretion of mucous glands. The muscle layer of the membranous part of the tracheal wall is well developed even in newborns, elastic fabric is found in relatively small quantities.

A child's trachea is soft and easily compressed; under the influence of inflammatory processes, stenotic phenomena easily occur. The trachea is mobile to some extent and can be displaced under the influence of unilateral pressure (exudate, tumor).

Bronchi. The right bronchus is like a continuation of the trachea, the left one extends at a large angle; This explains the more frequent entry of foreign bodies into the right bronchus. The bronchi are narrow, their cartilage is soft, muscle and elastic fibers are relatively poorly developed, the mucous membrane is rich in blood vessels, but relatively dry.

The lungs of a newborn weigh about 50 g, by 6 months their weight doubles, by one year it triples, and by 12 years it reaches 10 times its original weight;

in adults, the lungs weigh almost 20 times more than at birth. The right lung is usually slightly larger than the left. In young children, the pulmonary fissures are often weakly expressed, only in the form of shallow grooves on the surface of the lungs; Especially often, the middle lobe of the right lung almost merges with the upper one. The large, or main, oblique fissure separates the lower lobe from the upper and middle share th, and the small horizontal one passes between the upper and middle lobes. There is only one slot on the left.

The differentiation of individual cellular elements must be distinguished from the growth of lung mass. The main anatomical and histological unit of the lung is the acinus, which, however, has a relatively primitive character in children under 2 years of age. From 2 to 3 years, cartilaginous muscular bronchi develop vigorously; from 6 to 7 years of age, the histostructure of the acinus basically coincides with that of an adult; The sacculi that are sometimes encountered no longer have a muscular layer. Interstitial (connective) tissue in children is loose and rich in lymphatic and blood vessels. Children's lung poor elastic tissue, especially around the alveoli.

The epithelium of the alveoli in non-breathing stillborns is cubic, in breathing newborns and in older children it is flat.

The differentiation of the child's lung is thus characterized by quantitative and qualitative changes: a decrease in respiratory bronchioles, the development of alveoli from the alveolar ducts, an increase in the capacity of the alveoli themselves, a gradual reverse development of intrapulmonary connective tissue layers and an increase in elastic elements.

The volume of the lungs of already breathing newborns is 70 cm3, by the age of 15 their volume increases 10 times and in adults - 20 times. The overall growth of the lungs occurs mainly due to an increase in the volume of the alveoli, while the number of the latter remains more or less constant.

The breathing surface of the lungs in children is relatively larger than in adults; The contact surface of alveolar air with the vascular pulmonary capillary system decreases relatively with age. The amount of blood flowing through the lungs per unit time is greater in children than in adults, which creates the most favorable conditions for gas exchange.

Children, especially young children, are prone to pulmonary atelectasis and hypostasis, the occurrence of which is favored by the richness of the lungs in blood and insufficient development of elastic tissue.

The mediastinum in children is relatively larger than in adults; in its upper part it contains the trachea, large bronchi, thymus gland and lymph nodes, arteries and large nerve trunks, in its lower part there are the heart, blood vessels and nerves.

Lymph nodes. The following groups are distinguished: lymph nodes in the lungs: 1) tracheal, 2) bifurcation, 3) bronchopulmonary (at the point where the bronchi enter the lungs) and 4) nodes of large vessels. These groups of lymph nodes are connected by lymphatic pathways to the lungs, mediastinal and supraclavicular nodes (Fig. 49).

Rib cage. Relatively large lungs, heart and mediastinum occupy relatively more space in the child's chest and determine some of its features. The chest is always in a state of inhalation, the thin intercostal spaces are smoothed out, and the ribs are pressed quite strongly into the lungs.

In very young children, the ribs are almost perpendicular to the spine, and increasing the capacity of the chest by raising the ribs is almost impossible. This explains the diaphragmatic nature of breathing at this age. In newborns and children in the first months of life, the anteroposterior and lateral diameters of the chest are almost equal, and the epigastric angle is very obtuse.

As the child ages, the cross-section of the chest takes on an oval or kidney-shaped shape.

The frontal diameter increases, the sagittal diameter decreases relatively, and the curvature of the ribs increases significantly; the epigastric angle becomes more acute.

These ratios are characterized by the thoracic index (the percentage ratio between the anteroposterior and transverse diameters of the chest): in the fetus of the early embryonic period it is 185, in a newborn - 90, by the end of the year - 80, by 8 years - 70, after puberty period, it increases slightly again and fluctuates around 72-75.

The angle between the costal arch and the medial section of the chest in a newborn is approximately 60°, by the end of the 1st year of life - 45°, at the age of 5 years - 30°, at 15 years - 20° and after the end of puberty --about 15°.

The position of the sternum also changes with age; its upper edge, lying in a newborn at the level of the VII cervical vertebra, by the age of 6-7 years descends to the level of the II-III thoracic vertebrae. The dome of the diaphragm, which reaches the upper edge of the fourth rib in infants, drops somewhat lower with age.

From the above it is clear that the chest in children gradually moves from the inspiratory position to the expiratory position, which is the anatomical prerequisite for the development of the thoracic (costal) type of breathing.

The structure and shape of the chest can vary significantly depending on individual characteristics child. The shape of the chest in children is especially easily affected by past diseases (rickets, pleurisy) and various negative effects. environment. Age anatomical features The chest also determines some physiological characteristics of the breathing of children in different periods of childhood.

The first breath of a newborn. During the period of intrauterine development in the fetus, gas exchange occurs exclusively due to the placental circulation. At the end of this period, the fetus develops regular intrauterine respiratory movements, indicating the ability of the respiratory center to respond to irritation. From the moment the baby is born, gas exchange stops due to the placental circulation and pulmonary respiration begins.

The physiological causative agent of the respiratory center is a lack of oxygen and carbon dioxide, the increased accumulation of which from the moment of cessation of placental circulation is the cause of the newborn’s first deep breath; it is possible that the cause of the first breath should be considered not so much an excess of carbon dioxide in the blood of a newborn, but mainly a lack of oxygen in it.

The first breath, accompanied by the first cry, in most cases appears in the newborn immediately - as soon as the passage of the fetus through the mother's birth canal ends. However, in cases where a child is born with a sufficient supply of oxygen in the blood or there is a slightly reduced excitability of the respiratory center, several seconds, and sometimes even minutes, pass until the first breath appears. This short-term holding of breath is called neonatal apnea.

After the first deep breath, healthy children establish correct and mostly fairly uniform breathing; The uneven breathing rhythm observed in some cases during the first hours and even days of a child’s life usually quickly levels out.

The respiratory rate in newborns is about 40-60 per minute; With age, breathing becomes more rare, gradually approaching the rhythm of an adult. According to our observations, the respiratory rate in children is as follows.

Age of children

Until the age of 8, boys breathe more frequently than girls; In the prepubertal period, girls are ahead of boys in breathing frequency, and in all subsequent years their breathing remains more frequent.

Children are characterized by mild excitability of the respiratory center: mild physical stress and mental arousal, minor increases body and ambient air temperatures almost always cause a significant increase in breathing, and sometimes some disruption of the correct respiratory rhythm.

On average, one respiratory movement in newborns accounts for 2"/2 -3 pulse beats, in children at the end of the 1st year of life and older - 3--4 beats, and, finally, in adults - 4--5 heart beats. contractions These ratios are usually maintained when the pulse and breathing increase under the influence of physical and mental stress.

Breath volume. To assess the functional capacity of the respiratory organs, the volume of one respiratory movement, minute volume of breathing and vital capacity of the lungs are usually taken into account.

The volume of each respiratory movement in a newborn is able to good sleep is on average 20 cm3, in a one-month-old child it rises to approximately 25 cm3, by the end of the year it reaches 80 cm3, by 5 years - about 150 cm3, by 12 years - on average about 250 cm3 and by 14-16 years it rises to 300--400 cm3; however, this value, apparently, can fluctuate within fairly wide individual limits, since the data of different authors differ greatly. When screaming, the volume of breathing increases sharply - 2-3 or even 5 times.

The minute volume of breathing (the volume of one breath multiplied by the number of respiratory movements) quickly increases with age and is approximately equal to 800-900 cm3 in a newborn, 1400 cm3 in a child aged 1 month, and about 2600 cm3 by the end of the 1st year. , at the age of 5 years - about 3200 cm3 and at 12-15 years - about 5000 cm3.

The vital capacity of the lungs, i.e. the amount of air maximally exhaled after maximal inhalation, can only be indicated for children starting from 5-6 years old, since the research methodology itself requires the active participation of the child; at 5--6 years old, the vital capacity fluctuates around 1150 cm3, at 9--10 years old - about 1600 cm3 and at 14--16 years old - 3200 cm3. Boys have a larger lung capacity than Girls; The greatest lung capacity occurs with thoracoabdominal breathing, the smallest with purely chest breathing.

The type of breathing varies depending on the age and gender of the child; in children of the newborn period predominates diaphragmatic breathing with minor participation of the costal muscles. In infants, so-called thoracic-abdominal breathing with a predominance of diaphragmatic breathing is detected; excursions of the chest are weakly expressed in its upper parts and, conversely, much stronger in the lower parts. As the child moves from a constant horizontal position to a vertical position, the type of breathing also changes; at this age (the beginning of the 2nd year of life) it is characterized by a combination of diaphragmatic and chest breathing, and in some cases one predominates, in others the other. At the age of 3-7 years, due to the development of the muscles of the shoulder girdle, thoracic breathing becomes more and more clearly visible, beginning to definitely dominate over diaphragmatic breathing.

The first differences in the type of breathing depending on gender begin to clearly appear at the age of 7-14 years; During the prepubertal and pubertal periods, boys develop mainly the abdominal type, and girls develop the thoracic type of breathing. Age-related changes in the type of breathing are predetermined by the above-mentioned anatomical features of the chest of children at different periods of life.

Increasing the capacity of the chest by raising the ribs in infants is almost impossible due to the horizontal position of the ribs; it becomes possible in later periods, when the ribs drop somewhat downwards and anteriorly and when they are raised, the anteroposterior and lateral dimensions of the chest increase.

Features of breathing regulation

As is known, the act of breathing is regulated by the respiratory center, whose activity is characterized by automaticity and rhythm. The respiratory center is located in the middle third of the medulla oblongata on either side of the midline. Excitation, rhythmically arising in the cells of the respiratory center, is transmitted through centrifugal (efferent) nerve pathways to the respiratory muscles. Various irritations affecting the extero- and interoreceptors of the human body travel through centripetal pathways to the respiratory center and affect the processes of excitation and inhibition that occur in it; The role of impulses coming from the lungs themselves is especially great when irritating numerous receptors located in the bronchioles and alveoli;

the excitation that occurs during inhalation in these interoceptors is transmitted along the fibers of the vagus nerve to the respiratory center and inhibits its activity; the inhibited center does not send exciting impulses to the respiratory muscles, and they relax, and the exhalation phase begins; in a collapsed lung, the afferent endings of the vagus nerve are not excited, therefore, the inhibitory influence coming through its fibers is eliminated, the respiratory center is excited again, the resulting impulses are sent to the respiratory muscles and a new breath occurs; self-regulation occurs: inhalation causes exhalation, and the latter causes inhalation. Of course, the composition of the alveolar air also plays a role.

Consequently, the regulation of breathing in children is carried out mainly by the neuro-reflex pathway. Irritation of the endings of the centripetal nerves of the skin, muscles, vascular reflexogenic zones, endings of the sinocarotid nerve, etc., in the same reflex way, affects the rhythm and depth of breathing. The composition of the blood, the content of oxygen and carbon dioxide in it, the reaction of the blood, the accumulation of lactic acid or various pathological metabolic products in it also affect the function of the respiratory center; these irritations can be transmitted to it as a result of the influence of the blood composition on the receptors embedded in the walls of the vessels themselves, as well as as a result of the direct effect on the respiratory center of the composition of the blood washing it (humoral influence).

The function of the respiratory center of the medulla oblongata is constantly regulated by the cerebral cortex. The rhythm of breathing and its depth change under the influence of various emotional moments; an adult and older children can voluntarily change both the depth and frequency of breathing and can hold it for a while. Experiments on animals and observations in humans have proven the possibility of conditionally reflex influences for breathing. All this speaks to the regulatory role of the cerebral cortex. In very young children, it is often necessary to observe disturbances in the rhythm of breathing, even short-term complete cessation of breathing, for example in premature infants, which must be explained by the morphological immaturity of their central and peripheral nervous systems and, in particular, the cerebral cortex. A slight disturbance in the rhythm of breathing during sleep and in older children must be explained by the unique relationship between the cortex and the subcortical region of the brain.

The regulatory role of the central nervous system ensures the integrity of the body and explains the dependence of breathing on the function of other organs - the circulatory system, digestion, blood system, metabolic processes, etc. The close dependence of the function of some organs on the function of others is especially clearly reflected in children with less perfect regulation of cortico-visceral connections.

Protective reflexes from the mucous membranes of the respiratory tract - sneezing and coughing - are expressed, although less clearly, already in children of the newborn period.

In development respiratory system There are several stages:

Stage 1 – before the 16th week of intrauterine development, the formation of bronchial glands occurs.

From the 16th week - the recanalization stage - cellular elements begin to produce mucus and fluid and, as a result, the cells are completely displaced, the bronchi acquire lumen, and the lungs become hollow.

Stage 3 - alveolar - begins from 22 - 24 weeks and continues until the birth of the child. During this period, the formation of the acini, alveoli, and the synthesis of surfactant occurs.

By the time of birth, there are about 70 million alveoli in the fetal lungs. From 22-24 weeks, differentiation of alveolocytes begins - the cells lining inner surface alveoli

There are 2 types of alveolocytes: type 1 (95%), type 2 – 5%.

Surfactant is a substance that prevents alveoli from collapsing due to changes in surface tension.

It lines the alveoli from the inside thin layer, during inspiration, the volume of the alveoli increases, surface tension increases, which leads to respiratory resistance.

During exhalation, the volume of the alveoli decreases (more than 20-50 times), surfactant prevents their collapse. Since 2 enzymes are involved in the production of surfactant, they are activated by different dates gestation (at the latest from 35-36 weeks), it is clear that the shorter the child’s gestational age, the more pronounced the surfactant deficiency and the higher the likelihood of developing bronchopulmonary pathology.

Surfactant deficiency also develops in mothers with preeclampsia, during complicated pregnancy, caesarean section. The immaturity of the surfactant system is manifested by the development of respiratory distress syndrome.

Surfactant deficiency leads to collapse of the alveoli and the formation of atelectasis, as a result of which the function of gas exchange is disrupted, the pressure in the pulmonary circulation increases, which leads to the persistence of the fetal circulation and the functioning of the open ductus arteriosus and oval window.

As a result, hypoxia and acidosis develop, vascular permeability increases and the liquid part of the blood with proteins sweats into the alveoli. Proteins are deposited on the wall of the alveoli in the form of half rings - hyaline membranes. This leads to impaired diffusion of gases and the development of severe respiratory failure, which is manifested by shortness of breath, cyanosis, tachycardia, and the participation of auxiliary muscles in the act of breathing.

The clinical picture develops within 3 hours from the moment of birth and changes increase within 2-3 days.

AFO of the respiratory organs

By the time a child is born, the respiratory system reaches morphological maturity and can perform the function of breathing.
In a newborn, the respiratory tract is filled with a liquid that has low viscosity and a small amount of protein, which ensures its rapid absorption after the birth of the child through the lymphatic and blood vessels. In the early neonatal period, the child adapts to extrauterine existence.
After 1 inhalation, a short inspiratory pause occurs, lasting 1-2 seconds, after which exhalation occurs, accompanied by a loud cry of the child. In this case, the first respiratory movement in a newborn is carried out according to the type of gasping (inspiratory “flash”) - this is deep breath with difficulty breathing. Such breathing persists in healthy full-term infants until the first 3 hours of life. In a healthy newborn baby, with the first exhalation, most of the alveoli expand, and at the same time, vasodilation occurs. Complete expansion of the alveoli occurs within the first 2-4 days after birth.
The mechanism of the first breath. The main trigger is hypoxia, which occurs as a result of clamping of the umbilical cord. After ligation of the umbilical cord, oxygen tension in the blood drops, carbon dioxide pressure increases and pH decreases. In addition, a newborn baby is greatly influenced by the ambient temperature, which is lower than in the womb. Contraction of the diaphragm creates negative pressure in the chest cavity, which allows air to enter the airways more easily.

A newborn child has well-expressed defensive reflexes– cough and sneezing. Already in the first days after the birth of a child, the Hering-Breuer reflex functions, which, at threshold stretching of the pulmonary alveoli, leads to the transition of inhalation to exhalation. In an adult, this reflex occurs only with very strong stretching of the lungs.

Anatomically, the upper, middle and lower respiratory tract are distinguished. The nose is relatively small at the time of birth, the nasal passages are narrow, there is no lower nasal passage, turbinate, which are formed by the age of 4. Submucosal tissue is poorly developed (matures by 8-9 years), cavernous or cavernous tissue is underdeveloped up to 2 years (as a result, young children do not experience nosebleeds). The nasal mucosa is delicate, relatively dry, and rich in blood vessels. Due to the narrowness of the nasal passages and the abundant blood supply to their mucous membrane, even minor inflammation causes difficulty breathing through the nose in young children. Breathing through the mouth is impossible in children in the first half of life, since the large tongue pushes the epiglottis backward. The exit from the nose - the choanae - is especially narrow in young children, which is often the cause of long-term disruption of nasal breathing in them.

The paranasal sinuses in young children are very poorly developed or completely absent. As the facial bones increase in size ( upper jaw) and teeth erupt, the length and width of the nasal passages and the volume of the paranasal sinuses increase. These features explain the rarity of diseases such as sinusitis, frontal sinusitis, ethmoiditis in early childhood. A wide nasolacrimal duct with underdeveloped valves contributes to the transfer of inflammation from the nose to the mucous membrane of the eyes.

The pharynx is narrow and small. The lymphopharyngeal ring (Waldeyer-Pirogov) is poorly developed. It consists of 6 tonsils:

2 palatines (between the anterior and posterior palatines)

2 tubes (near the Eustachian tubes)

1 throat (in the upper part of the nasopharynx)

1 lingual (in the area of the root of the tongue).

The palatine tonsils are not visible in newborns; by the end of the 1st year of life they begin to protrude from behind the palatine arches. By the age of 4-10 years, the tonsils are well developed and their hypertrophy can easily occur. During puberty, the tonsils begin to undergo reverse development. The Eustachian tubes in young children are wide, short, straight, located horizontally and at horizontal position child, the pathological process from the nasopharynx easily spreads to the middle ear, causing the development of otitis media. With age they become narrow, long, and tortuous.

The larynx has a funnel shape. The glottis is narrow and located high (at the level of the 4th cervical vertebra, and in adults - at the level of the 7th cervical vertebra). Elastic tissue is poorly developed. The larynx is relatively longer and narrower than in adults; its cartilage is very pliable. With age, the larynx acquires a cylindrical shape, becomes wide and descends 1-2 vertebrae lower. The false vocal cords and mucous membrane are delicate, rich in blood and lymphatic vessels, elastic tissue is poorly developed. The glottis in children is narrow. Young children's vocal cords are shorter than those of older children, which is why they have a high-pitched voice. From the age of 12, boys' vocal cords become longer than girls'.

The bifurcation of the trachea lies higher than in an adult. The cartilaginous frame of the trachea is soft and easily narrows the lumen. Elastic tissue is poorly developed, the mucous membrane of the trachea is tender and richly supplied with blood vessels. The growth of the trachea occurs in parallel with the growth of the body, most intensively in the 1st year of life and during puberty.

The bronchi are richly supplied with blood, muscle and elastic fibers in young children are underdeveloped, and the lumen of the bronchi is narrow. Their mucous membrane is richly vascularized.
The right bronchus is like a continuation of the trachea; it is shorter and wider than the left. This explains the frequent entry of a foreign body into the right main bronchus.
The bronchial tree is poorly developed.
There are 1st order bronchi - main, 2nd order - lobar (3 on the right, 2 on the left), 3rd order - segmental (10 on the right, 9 on the left). The bronchi are narrow, their cartilage is soft. Muscle and elastic fibers in children of the 1st year of life are not yet sufficiently developed, the blood supply is good. The mucous membrane of the bronchi is lined with ciliated epithelium, which provides mucociliary clearance, which plays a major role in protecting the lungs from various pathogens from the upper respiratory tract and has an immune function ( secretory immunoglobulin A). The tenderness of the bronchial mucosa and the narrowness of their lumen explain frequent occurrence in young children, bronchiolitis with complete or partial obstruction syndrome, pulmonary atelectasis.

Lung tissue is less airy, elastic tissue is underdeveloped. IN right lung There are 3 lobes, the left one has 2. Then the lobar bronchi are divided into segmental ones. A segment is an independently functioning unit of the lung, with its apex directed towards the root of the lung, and has an independent artery and nerve. Each segment has independent ventilation, a terminal artery and intersegmental septa made of elastic connective tissue. The segmental structure of the lungs is already well expressed in newborns. There are 10 segments in the right lung, and 9 in the left lung. The upper left and right lobes are divided into three segments - 1, 2 and 3rd, the middle right lobe - into two segments - 4th and 5th. In the left light medium The lobe corresponds to the lingual lobe, also consisting of two segments - the 4th and 5th. The lower lobe of the right lung is divided into five segments - 6, 7, 8, 9 and 10th, the left lung - into four segments - 6, 7, 8 and 9th. The acini are underdeveloped, the alveoli begin to form from 4 to 6 weeks of life and their number rapidly increases within 1 year, increasing up to 8 years.

The oxygen requirement in children is much higher than in adults. Thus, in children of the 1st year of life, the need for oxygen per 1 kg of body weight is about 8 ml/min, in adults - 4.5 ml/min. The shallow nature of breathing in children is compensated by a high breathing frequency, the participation of most of the lungs in breathing

In the fetus and newborn, hemoglobin F predominates, which has an increased affinity for oxygen, and therefore the dissociation curve of oxyhemoglobin is shifted to the left and up. Meanwhile, in a newborn, like in a fetus, red blood cells contain extremely little 2,3-diphosphoglycerate (2,3-DPG), which also causes less saturation of hemoglobin with oxygen than in an adult. At the same time, in the fetus and newborn, oxygen is more easily transferred to the tissues.

In healthy children, depending on age, different breathing patterns are determined:

a) vesicular - exhalation is one third of inhalation.

b) puerile breathing - enhanced vesicular

c) hard breathing - exhalation is more than half of the inhalation or equal to it.

d) bronchial breathing - exhalation is longer than inhalation.

It is also necessary to note the sonority of breathing (normal, increased, weakened). In children of the first 6 months. breathing is weakened. After 6 months up to 6 years of age, breathing is puerile, and from 6 years of age - vesicular or intensely vesicular (one third of inhalation and two thirds of exhalation are heard), it is heard evenly over the entire surface.

Respiratory rate (RR)

	Frequency per minute
Premature
Newborn

Stange test - holding your breath while inhaling (6-16 years old - from 16 to 35 seconds).

Gench's test - holding your breath while exhaling (N - 21-39 seconds).

One of the actions carried out during examination by a pediatrician is counting respiratory movements. This seemingly simple indicator carries important information about the state of health in general and about the functioning of the respiratory organs and cardiovascular system in particular.

How to correctly calculate the respiratory rate (RR) per minute? This is not particularly difficult. But certain difficulties arise with the interpretation of the data. This is in to a greater extent concerns young parents, because, having received a result from a child several times higher than their own, they panic. Therefore, in this article we propose to figure out what the normal respiratory rate is for children. The table will help us with this.

Features of the child's respiratory system

The first thing an expectant mother has been waiting for for so long is the baby's first cry. It is with this sound that his first breath occurs. By the time of birth, the organs that ensure the child’s breathing are not yet fully developed, and only with the growth of the body itself do they mature (both functionally and morphologically).

The nasal passages (which are the upper respiratory tract) in newborns have their own characteristics:
. They are quite narrow.
. Relatively short.
. Their inner surface is delicate, with a huge number of vessels (blood, lymphatic).

Therefore, even with minor symptoms, the child’s nasal mucosa quickly swells, the already small lumen decreases, and as a result, breathing becomes difficult and shortness of breath develops: small children cannot yet breathe through their mouths. How younger child, the more dangerous the consequences can be, and the faster it is necessary to eliminate the pathological condition.

Lung tissue in young children also has its own characteristics. Unlike adults, their lung tissue is poorly developed, and the lungs themselves have a small volume with a huge number of blood vessels.

Rules for counting breathing rate

Measuring respiratory rate does not require any special skills or equipment. All you need is a stopwatch (or a watch with a second hand) and following simple rules.

The person should be calm and in a comfortable position. If we're talking about For children, especially young children, it is better to count respiratory movements during sleep. If this is not possible, the subject should be distracted from the manipulation as much as possible. To do this, just grab your wrist (where the pulse is usually detected) and meanwhile count your breathing rate. It should be noted that the pulse in children under one year old (about 130-125 beats per minute) should not cause concern - this is the norm.

In infants, it is strongly recommended to count the respiratory rate during sleep, since crying can significantly affect the result and give deliberately false numbers. By placing your hand on the anterior abdominal wall (or just visually), you can easily carry out this study.

Considering that breathing has its own rhythmic cycle, it is necessary to observe the duration of its counting. Be sure to measure your respiratory rate over the course of a full minute, rather than multiplying the result obtained in just 15 seconds by four. It is recommended to carry out three counts and calculate the average.

Normal respiratory rate in children

The table shows the normal respiratory rate. Data are presented for children of different age groups.

As we can see from the table, the frequency of respiratory movements per minute is higher, the younger the child. Gradually, as they grow older, their number decreases, and by puberty When a child turns 14-15 years old, the respiratory rate becomes equal to that of a healthy adult. No differences by gender are observed.

Types of breathing

There are three main types of breathing in both adults and children: chest, abdominal and mixed.

The breast type is more typical for females. With it, inhalation/exhalation is ensured to a greater extent due to movements of the chest. The disadvantage of this type of breathing movement is poor ventilation. lower sections lung tissue. Whereas with the abdominal type, when the diaphragm is more involved (and the anterior one visually moves when breathing abdominal wall), lack of ventilation upper sections lungs. This type respiratory movements are more common in men.

But with a mixed type of breathing, a uniform (identical) expansion of the chest occurs with an increase in the volume of its cavity in all four directions (upper-lower, lateral). This is the most correct one, which ensures optimal ventilation of the entire lung tissue.

Normally, the respiratory rate in a healthy adult is 16-21 per minute, in newborns - up to 60 per minute. Above, the norm of respiratory rate in children is given in more detail (table with age norms).

Rapid breathing

The first sign of respiratory damage, especially when infectious diseases, is However, there will certainly be other signs colds(cough, runny nose, wheezing, etc.). Quite often, when body temperature rises, the respiratory rate increases and the pulse quickens in children.

Holding your breath during sleep

Quite often, young children (especially infants) experience short-term pauses in breathing during sleep. This physiological feature. But if you notice that such episodes become more frequent, their duration becomes longer, or other symptoms occur, such as blue lips or loss of consciousness, you should immediately call " Ambulance"to prevent irreversible consequences.

Conclusion

The respiratory organs have a number of features that contribute to their frequent damage and rapid decompensation of the condition. This is primarily due to their immaturity at the time of birth, certain anatomical and physiological characteristics, incomplete differentiation of the structures of the central nervous system and their direct influence on the respiratory center and respiratory organs.
The younger the child, the less lung capacity he has, and therefore the more he will need to do more respiratory movements (inhalation/exhalation) to provide the body with the necessary amount of oxygen.

Summing up

It should be remembered that respiratory arrhythmia is quite common in children in the first months of life. Most often this is not pathological condition, but only indicates age-related characteristics.

So, now you know what the normal respiratory rate is for children. The table of averages should be taken into account, but there is no need to panic when small deviations. And be sure to consult your doctor before jumping to conclusions!

The respiratory system is a set of organs consisting of the respiratory tract (nose, pharynx, trachea, bronchi), lungs ( bronchial tree, acini), as well as muscle groups that promote contraction and relaxation of the chest. Breathing provides the body's cells with oxygen, which in turn convert it into carbon dioxide. This process occurs in the pulmonary circulation.

The formation and development of the child’s respiratory system begins during the 3rd week of a woman’s pregnancy. Formed from three primordia:

Splanchnotome.
Mesenchyme.
Epithelium of the foregut.

The pleural mesothelium develops from the visceral and parietal layers of the splanchnotome. It is represented by a single-layer squamous epithelium (polygonal cells), lining the entire surface of the pulmonary system, separating it from other organs. The outer surface of the leaf is covered with microcilia that produce serous fluid. It is necessary for the two layers of pleura to slide between each other during inhalation and exhalation.

From the mesenchyme, namely the germ layer of the mesoderm, cartilage, muscle and connective tissue structures, and blood vessels are formed. The bronchial tree, lungs, and alveoli develop from the epithelium of the foregut.

During the prenatal period, the respiratory tract and lungs are filled with fluid, which is removed during childbirth with the first breath, and is also absorbed by the lymph system and partially into the blood vessels. Breathing is carried out by maternal blood enriched with oxygen through the umbilical cord.

By the eighth month of gestation, pneumocytes produce a surfactant - surfactant. It lines the inner surface of the alveoli, prevents them from collapsing and sticking together, and is located at the air-liquid interface. Protects against harmful agents with the help of immunoglobulins and macrophages. Insufficient secretion or absence of surfactant threatens the development of respiratory distress syndrome.

A feature of the respiratory system in children is its imperfection. The formation and differentiation of tissues and cellular structures is carried out in the first years of life and up to seven years.

Structure

Over time, the child’s organs adapt to the environment in which he will live, and the necessary immune and glandular cells are formed. In a newborn, the respiratory tract, unlike an adult body, has:

Narrower clearance.
Short stroke lengths.
Many vascular vessels in a limited area of the mucosa.
The delicate, easily traumatized architectonics of the lining membranes.
Loose structure of lymphoid tissue.

Upper paths

Baby's nose small size, its passages are narrow and short, so the slightest swelling can lead to obstruction, which will complicate the sucking process.

Structure upper paths in a child:

Two nasal sinuses are developed - the upper and middle, the lower one will be formed by the age of four. The cartilage frame is soft and pliable. The mucous membrane has an abundance of blood and lymphatic vessels, and therefore minor manipulation can lead to injury. Rarely noted nosebleed– this is due to undeveloped cavernous tissue (it will be formed by the age of 9). All other cases of bleeding from the nose are considered pathological.
The maxillary sinuses, frontal and ethmoid sinuses are not closed, protrude the mucous membrane, are formed by 2 years, cases of inflammatory lesions are rare. Thus, the shell is more adapted to cleansing and humidifying the inhaled air. Full development of all sinuses occurs by age 15.
The nasolacrimal duct is short, exits in the corner of the eye, close to the nose, which ensures rapid upward spread of inflammation from the nose to the lacrimal sac and the development of polyetiological conjunctivitis.
The pharynx is short and narrow, which allows it to quickly become infected through the nose. At the level between the oral cavity and the pharynx there is a nasopharyngeal ring-shaped Pirogov-Waldeyer formation, consisting of seven structures. The concentration of lymphoid tissue protects the entrance to the respiratory and digestive organs from infectious agents, dust, and allergens. Features of the structure of the ring: poorly formed tonsils, adenoids, they are loose, susceptible to colonization of inflammatory agents in their crypts. Chronic foci of infection, frequent respiratory diseases, sore throats, and difficulty in nasal breathing occur. Such children appear neurological disorders, they usually walk with their mouths open and are less amenable to school training.
The epiglottis is scapula-shaped, relatively wide and short. During breathing, it rests on the root of the tongue - it opens the entrance to the lower passages; during the period of eating, it prevents foreign bodies from entering the respiratory passages.

Lower Paths

The larynx of a newborn is located higher than that of an adult and is very mobile due to the muscular frame. It looks like a funnel with a diameter of 0.4 cm, the narrowing is directed towards the vocal cords. The chords are short, which explains the high timbre of the voice. With slight swelling, during acute respiratory diseases, symptoms of croup and stenosis occur, which are characterized by heavy, wheezing breathing with the inability to take a full breath. As a result, hypoxia develops. The laryngeal cartilages are rounded, their sharpening in boys occurs by the age of 10–12 years.

At the time of birth, the trachea is already formed, located at the level of the 4th cervical vertebra, mobile, funnel-shaped, then acquires a cylindrical appearance. The lumen is significantly narrowed, unlike in an adult; there are few glandular areas in it. When coughing it can shrink by a third. Taking into account the anatomical features, when inflammatory processes, inevitable narrowing and emergence barking cough, symptoms of hypoxia (cyanosis, shortness of breath). The tracheal framework consists of cartilaginous half-rings, muscle structures, and a connective tissue membrane. The bifurcation at birth is higher than in older children.

The bronchial tree is a continuation of the tracheal bifurcation and is divided into the right and left bronchus. The right one is wider and shorter, the left one is narrower and longer. The ciliated epithelium is well developed, producing physiological mucus that cleanses the bronchial lumen. Mucus moves outward with cilia at a speed of up to 0.9 cm per minute.

A feature of the respiratory system in children is a weak cough impulse, due to poorly developed torso muscles, incomplete myelin coating nerve fibers tenth pair cranial nerves. As a result, infected sputum does not pass away, accumulates in the lumen of bronchi of different sizes and becomes clogged with thick secretions. The structure of the bronchus contains cartilaginous rings, with the exception of the terminal sections, which consist only of smooth muscles. When they are irritated, it may occur sharp narrowing progress - an asthmatic picture appears.

The lungs are airy tissue, their differentiation continues until the age of 9, they consist of:

Lobes (right of three, left of two).
Segments (right – 10, left – 9).
Dolek.

The bronchioles end in a sac in the baby. As the child grows, lung tissue grows, the sacs turn into alveolar clusters, and vital capacity indicators increase. Active development from 5 weeks of life. At birth, the weight of the paired organ is 60–70 grams, well supplied with blood and vascularized with lymph. Thus, it is full-blooded, and not airy as in older people. An important point is that the lungs are not innervated, inflammatory reactions are painless, and in this case, you can miss a serious illness.

Due to the anatomical and physiological structure, pathological processes develop in the basal regions, cases of atelectasis and emphysema are common.

Functional Features

The first breath is carried out due to a decrease in oxygen in the blood of the fetus and an increase in the level of carbon dioxide, after clamping the umbilical cord, as well as a change in living conditions - from warm and humid to cold and dry. Signals by nerve endings enter the central nervous system and then to the respiratory center.

Features of respiratory function in children:

Conducting air.
Cleaning, warming, moisturizing.
Saturation with oxygen and purification from carbon dioxide.
Protective immune function, synthesis of immunoglobulins.
Metabolism – synthesis of enzymes.
Filtration – dust, blood clots.
Lipid and water metabolism.
Shallow breaths.
Tachypnea.

In the first year of life, respiratory arrhythmia occurs, which is considered normal, but its persistence and the occurrence of apnea after one year old is fraught with respiratory arrest and death.

The frequency of breathing movements directly depends on the age of the baby - the younger, the more often the breath is taken.

NPV norm:

Newborn 39–60/minute.
1–2 years – 29–35/min.
3–4 years – 23–28/min.
5–6 years – 19–25/min.
10 years – 19–21/min.
Adult – 16–21/min.

Taking into account the characteristics of the respiratory system in children, the attentiveness and awareness of parents, timely examination, therapy reduces the risk of transition to chronic stage illness and serious complications.