Type of breathing in an infant. Physiological characteristics of the respiratory system in children
ANATOMICAL AND PHYSIOLOGICAL FEATURES OF THE RESPIRATORY SYSTEM
The formation of the tracheopulmonary system begins at the 3-4th week of embryonic development. Already by the 5-6th week of embryo development, second-order branches appear and the formation of three lobes of the right lung and two lobes of the left lung is predetermined. During this period, the trunk of the pulmonary artery is formed, growing into the lungs along the primary bronchi.
In the embryo, at the 6-8th week of development, the main arterial and venous collectors of the lungs are formed. Within 3 months, the bronchial tree grows, segmental and subsegmental bronchi appear.
During the 11-12th week of development there are already areas lung tissue. They, together with the segmental bronchi, arteries and veins, form the embryonic segments of the lungs.
Between the 4th and 6th months there is fast growth pulmonary vascular system.
In fetuses at 7 months, the lung tissue acquires the features of a porous canal structure; the future air spaces are filled with fluid, which is secreted by the cells lining the bronchi.
At 8–9 months of the intrauterine period, further development of the functional units of the lungs occurs.
The birth of a child requires the immediate functioning of the lungs; during this period, with the onset of breathing, significant changes occur in the airways, especially the respiratory part of the lungs. The formation of the respiratory surface in individual parts of the lungs occurs unevenly. For straightening breathing apparatus lungs, the condition and readiness of the surfactant film lining the lung surface are of great importance. Violation of the surface tension of the surfactant system leads to serious illnesses young child.
In the first months of life, the child maintains the ratio of the length and width of the airways, like a fetus, when the trachea and bronchi are shorter and wider than in adults, and the small bronchi are narrower.
The pleura covering the lungs in a newborn baby is thicker, looser, contains villi and outgrowths, especially in the interlobar grooves. Pathological foci appear in these areas. The lungs are prepared for the birth of a child to perform the respiratory function, but individual components are in the development stage, the formation and maturation of the alveoli is rapidly proceeding, and the small lumen is being restructured muscular arteries and elimination of the barrier function.
After three months of age, period II is distinguished.
I – period of intensive growth of the pulmonary lobes (from 3 months to 3 years).
II – final differentiation of the entire bronchopulmonary system (from 3 to 7 years).
Intensive growth of the trachea and bronchi occurs in the 1st-2nd year of life, which slows down in subsequent years, and small bronchi grow intensively, and the branching angles of the bronchi also increase. The diameter of the alveoli increases, and the respiratory surface of the lungs doubles with age. In children under 8 months, the diameter of the alveoli is 0.06 mm, in 2 years – 0.12 mm, in 6 years – 0.2 mm, in 12 years – 0.25 mm.
In the first years of life, growth and differentiation of lung tissue elements and blood vessels occur. The ratio of share volumes of individual segments is equalized. Already at 6–7 years of age, the lungs are a mature organ and are indistinguishable from the lungs of adults.
FEATURES OF THE RESPIRATORY TRACT
The respiratory tract is divided into the upper, which includes the nose, paranasal sinuses, pharynx, and Eustachian tubes, and the lower, which includes the larynx, trachea, and bronchi.
The main function of breathing is to conduct air into the lungs, cleanse it of dust particles, protect the lungs from harmful effects bacteria, viruses, foreign particles. In addition, the airways warm and humidify the inhaled air.
The lungs are represented by small sacs that contain air. They connect with each other. The main function of the lungs is to absorb oxygen from the atmospheric air and release gases, primarily carbon dioxide, into the atmosphere.
Breathing mechanism. When you inhale, the diaphragm and chest muscles contract. Exhalation in older age occurs passively under the influence of elastic traction of the lungs. With bronchial obstruction, emphysema, and also in newborns, active inhalation occurs.
Normally, breathing is established at a frequency at which the volume of breathing is performed due to the minimum energy expenditure of the respiratory muscles. In newborn children, the respiratory rate is 30–40, in adults – 16–20 per minute.
The main carrier of oxygen is hemoglobin. In the pulmonary capillaries, oxygen binds to hemoglobin to form oxyhemoglobin. In newborns, fetal hemoglobin predominates. On the first day of life, it is contained in the body about 70%, by the end of the 2nd week - 50%. Fetal hemoglobin has the ability to easily bind oxygen and difficult to release it to tissues. This helps the child in the presence of oxygen starvation.
Transport of carbon dioxide occurs in dissolved form; blood oxygen saturation affects the carbon dioxide content.
The respiratory function is closely related to pulmonary circulation. This is a complex process.
During breathing, autoregulation is noted. When the lung is stretched during inhalation, the inhalation center is inhibited, while exhalation is stimulated during exhalation. Deep breathing or forced inflation of the lungs leads to a reflex expansion of the bronchi and increases the tone of the respiratory muscles. When the lungs collapse and are compressed, the bronchi become narrowed.
The medulla oblongata contains the respiratory center, from where commands are sent to the respiratory muscles. The bronchi lengthen when you inhale, and shorten and narrow when you exhale.
The relationship between the functions of breathing and blood circulation manifests itself from the moment the lungs expand during the first breath of a newborn, when both the alveoli and blood vessels expand.
With respiratory diseases in children, respiratory dysfunction and respiratory failure may occur.
STRUCTURE FEATURES OF THE NOSE
In young children, the nasal passages are short, the nose is flattened due to an underdeveloped facial skeleton. The nasal passages are narrower, the conchae are thickened. The nasal passages are fully formed only by the age of 4 years. The nasal cavity is relatively small in size. The mucous membrane is very loose and well supplied with blood vessels. Inflammatory process leads to the development of edema and, because of this, a reduction in the lumen of the nasal passages. Mucus often stagnates in the nasal passages. It can dry out, forming crusts.
When the nasal passages close, shortness of breath may occur; during this period, the child cannot suckle, becomes anxious, abandons the breast, and remains hungry. Children, due to difficulty in nasal breathing, begin to breathe through their mouths, their warming of incoming air is disrupted and their susceptibility to colds increases.
If nasal breathing is impaired, there is a lack of discrimination of odors. This leads to a disturbance in appetite, as well as a disturbance in the understanding of the external environment. Breathing through the nose is physiological, breathing through the mouth is a sign of nasal disease.
Accessory nasal cavities. The paranasal cavities, or sinuses as they are called, are confined spaces filled with air. The maxillary (maxillary) sinuses are formed by the age of 7. Ethmoidal - by the age of 12, the frontal is fully formed by the age of 19.
Features of the nasolacrimal canal. Nasolacrimal duct shorter than in adults, its valves are not sufficiently developed, the outlet is located close to the corner of the eyelids. Due to these features, the infection quickly spreads from the nose to the conjunctival sac.
FEATURES OF THE PHARYN
The pharynx in young children is relatively wide, the palatine tonsils are poorly developed, which explains rare diseases sore throat in the first year of life. The tonsils are fully developed by the age of 4–5 years. By the end of the first year of life, almond tissue hyperplasias. But its barrier function at this age is very low. Overgrown almond tissue can be susceptible to infection, which is why diseases such as tonsillitis and adenoiditis occur.
The Eustachian tubes open into the nasopharynx and connect it to the middle ear. If an infection enters the middle ear from the nasopharynx, middle ear inflammation occurs.
FEATURES OF THE LARYNX
The larynx in children is funnel-shaped and is a continuation of the pharynx. In children, it is located higher than in adults, and has a narrowing in the area of the cricoid cartilage, where the subglottic space is located. The glottis is formed by the vocal cords. They are short and thin, which is responsible for the child’s high, sonorous voice. The diameter of the larynx in a newborn in the area of the subglottic space is 4 mm, at 5–7 years old – 6–7 mm, by 14 years old – 1 cm. Features of the larynx in children are: its narrow lumen, many nerve receptors, easily occurring swelling of the submucosal layer, which can lead to severe breathing problems.
The thyroid cartilages form a more acute angle in boys over 3 years of age; from the age of 10, a typical male larynx is formed.
FEATURES OF THE TRACHEA
The trachea is a continuation of the larynx. It is wide and short, and the tracheal frame consists of 14–16 cartilaginous rings, which are connected by a fibrous membrane instead of an elastic end plate in adults. The presence of a large number of muscle fibers in the membrane contributes to changes in its lumen.
Anatomically, the trachea of a newborn is at level IV cervical vertebra, and in an adult – at the level of the VI–VII cervical vertebra. In children, it gradually descends, as does its bifurcation, which is located in a newborn at the level of the third thoracic vertebra, in children 12 years old - at the level of V-VI thoracic vertebra.
During physiological breathing, the lumen of the trachea changes. During coughing, it decreases by 1/3 of its transverse and longitudinal dimensions. The mucous membrane of the trachea is rich in glands that secrete a secretion that covers the surface of the trachea with a layer 5 microns thick.
The ciliated epithelium promotes the movement of mucus at a speed of 10–15 mm/min from the inside to the outside.
The characteristics of the trachea in children contribute to the development of its inflammation - tracheitis, which is accompanied by a rough, low-pitched cough, reminiscent of a cough “like in a barrel”.
FEATURES OF THE BRONCHIAL TREE
The bronchi in children are formed at birth. Their mucous membrane is richly supplied blood vessels, covered with a layer of mucus, which moves at a speed of 0.25-1 cm/min. A feature of the bronchi in children is that elastic and muscle fibers are poorly developed.
The bronchial tree branches to bronchi of the 21st order. With age, the number of branches and their distribution remain constant. The size of the bronchi changes rapidly in the first year of life and during puberty. They are based on cartilaginous semirings in early childhood. Bronchial cartilage is very elastic, pliable, soft and easily displaced. The right bronchus is wider than the left and is a continuation of the trachea, so foreign bodies are more often found in it.
After the birth of a child, a cylindrical epithelium with a ciliated apparatus is formed in the bronchi. With hyperemia of the bronchi and their swelling, their lumen sharply decreases (up to its complete closure).
Underdevelopment of the respiratory muscles contributes to a weak cough impulse in small child, which can lead to blockage of small bronchi with mucus, and this, in turn, leads to infection of the lung tissue, disruption of the cleansing drainage function bronchi.
With age, as the bronchi grow, wide lumens of the bronchi appear, and the bronchial glands produce less viscous secretions, acute diseases of the bronchopulmonary system are less common compared to younger children.
FEATURES OF THE LUNG
The lungs in children, as in adults, are divided into lobes, and lobes into segments. The lungs have a lobular structure, the segments in the lungs are separated from each other by narrow grooves and partitions of connective tissue. The main structural unit is the alveoli. Their number in a newborn is 3 times less than in an adult. Alveoli begin to develop from 4-6 weeks of age, their formation occurs up to 8 years. After 8 years, the lungs in children increase due to their linear size, and the respiratory surface of the lungs increases in parallel.
The following periods can be distinguished in the development of the lungs:
1) from birth to 2 years, when intensive growth of the alveoli occurs;
2) from 2 to 5 years, when elastic tissue intensively develops, bronchi with peribronchial inclusions of lung tissue are formed;
3) from 5 to 7 years the functional abilities of the lungs are finally formed;
4) from 7 to 12 years, when a further increase in lung mass occurs due to the maturation of lung tissue.
Anatomically, the right lung consists of three lobes (upper, middle and lower). By 2 years, the sizes of the individual lobes correspond to each other, like in an adult.
In addition to the lobar division, segmental division is distinguished in the lungs, in right lung There are 10 segments, 9 on the left.
The main function of the lungs is breathing. It is believed that 10,000 liters of air pass through the lungs daily. Oxygen absorbed from the inhaled air ensures the functioning of many organs and systems; the lungs take part in all types of metabolism.
The respiratory function of the lungs is carried out with the help of a biologically active substance - surfactant, which also has a bactericidal effect, preventing fluid from entering the pulmonary alveoli.
The lungs remove waste gases from the body.
A feature of the lungs in children is the immaturity of the alveoli; they have a small volume. This is compensated by increased breathing: than younger child, the more shallow his breathing. The respiratory rate in a newborn is 60, in a teenager it is already 16–18 respiratory movements per minute. Lung development is completed by age 20.
A variety of diseases can disrupt the vital respiratory function of children. Due to the characteristics of aeration, drainage function and evacuation of secretions from the lungs, the inflammatory process is often localized in the lower lobe. This occurs when children are lying down infancy due to insufficient drainage function. Paravisceral pneumonia most often occurs in the second segment of the upper lobe, as well as in the basal-posterior segment of the lower lobe. The middle lobe of the right lung may often be affected.
Greatest diagnostic value have the following studies: x-ray, bronchology, determination of blood gas composition, blood pH, study of external respiration function, study of bronchial secretions, computed tomography.
By the frequency of breathing and its relationship with the pulse, the presence or absence of respiratory failure is judged (see Table 14).
Table 14 Age dynamics of respiratory rate (Fomin V.F., 2003)
source: Directory of Children's Diseases.
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Formation respiratory system in a child it begins at 3-4 weeks of intrauterine existence. By the 6th week of embryonic development, the child develops branches of the second-order respiratory organs. At the same time, the formation of the lungs begins. By the 12th week of the intrauterine period, areas of lung tissue appear in the fetus. Anatomical and physiological features - AFO of the respiratory organs in children undergo changes as the baby grows. Crucial proper development nervous system, which is involved in the breathing process.
Upper respiratory tract
In newborn babies, the skull bones are not sufficiently developed, due to which the nasal passages and the entire nasopharynx are small and narrow. The mucous membrane of the nasopharynx is delicate and riddled with blood vessels. It is more vulnerable than that of an adult. Nasal appendages are most often absent; they begin to develop only by 3-4 years.
As the baby grows, the nasopharynx also increases in size. By the age of 8, the baby develops a lower nasal passage. In children, the paranasal sinuses are located differently than in adults, due to which the infection can quickly spread into the cranial cavity.
In children, a strong proliferation of lymphoid tissue is observed in the nasopharynx. It reaches its peak by the age of 4, and from the age of 14 it begins to reverse development. Tonsils are a kind of filters, protecting the body from the penetration of microbes. But if a child is often sick for a long time, then the lymphoid tissue itself becomes a source of infection.
Children often suffer from respiratory diseases, which is due to the structure of the respiratory organs and insufficient development of the immune system.
Larynx
In small children, the larynx is narrow and funnel-shaped. Only later does it become cylindrical. The cartilages are soft, the glottis is narrowed and the vocal cords themselves are short. By age 12, boys' vocal cords become longer than girls'. This is what causes the change in voice timbre in boys.
Trachea
The structure of the trachea also differs in children. During the first year of life, it is narrow and funnel-shaped. By age 15 top part the trachea reaches the 4th cervical vertebra. By this time, the length of the trachea doubles, it is 7 cm. In children, it is very soft, so when the nasopharynx is inflamed, it is often compressed, which manifests itself as stenosis.
Bronchi
The right bronchus is like a continuation of the trachea, and the left one moves to the side at an angle. That is why in case of accidental hit foreign objects into the nasopharynx, they often end up in the right bronchus.
Children are susceptible to bronchitis. Any cold can result in inflammation of the bronchi, severe cough, high temperature and violation general condition baby.
Lungs
Children's lungs undergo changes as they grow older. The mass and size of these respiratory organs increase, and differentiation in their structure also occurs. In children, there is little elastic tissue in the lungs, but the intermediate tissue is well developed and contains a large number of vessels and capillaries.
The lung tissue is full-blooded and contains less air than in adults. By the age of 7, the formation of the acini ends, and until the age of 12, the growth of the formed tissue simply continues. By the age of 15, the alveoli increase 3 times.
Also, with age, the mass of the lung tissue in children increases, and more elastic elements appear in it. Compared to the neonatal period, the mass of the respiratory organ increases by approximately 8 times by the age of 7 years.
The amount of blood that flows through the capillaries of the lungs is higher than in adults, which improves gas exchange in the lung tissue.
Rib cage
The formation of the chest in children occurs as they grow and ends only closer to 18 years. According to the age of the child, the volume of the chest increases.
In infants, the sternum is cylindrical in shape, while in adults the chest is oval in shape. Children's ribs are located in a special way; due to their structure, a child can painlessly transition from diaphragmatic to chest breathing.
Peculiarities of breathing in a child
Children have an increased respiratory rate, with breathing movements becoming more frequent the smaller the child. From the age of 8, boys breathe more often than girls, but starting from adolescence, the girls begin to breathe more often and this state of affairs continues throughout the entire time.
To assess the condition of the lungs in children, it is necessary to consider the following parameters:
- Total volume of respiratory movements.
- The volume of air inhaled per minute.
- Vital capacity of the respiratory organs.
The depth of breathing in children increases as they grow older. The relative volume of breathing in children is twice as high as in adults. Vital capacity increases after physical activity or sports exercises. The more exercise stress, the more noticeable is the change in breathing pattern.
In a calm state, the child uses only part of the vital capacity of the lungs.
Vital capacity increases as the diameter of the chest increases. The amount of air that the lungs can ventilate in a minute is called the respiratory limit. This value also increases as the child grows older.
Gas exchange is of great importance for assessing pulmonary function. The carbon dioxide content in the exhaled air of schoolchildren is 3.7%, while in adults this value is 4.1%.
Methods for studying the respiratory system of children
To assess the condition of the child’s respiratory organs, the doctor collects an anamnesis. The little patient’s medical record is carefully studied and complaints are clarified. Next, the doctor examines the patient, listens to the lower respiratory tract with a stethoscope and taps them with his fingers, paying attention to the type of sound produced. Then the examination takes place according to the following algorithm:
- The mother is asked how the pregnancy progressed and whether there were any complications during childbirth. In addition, it is important what the baby was sick with shortly before the appearance of problems with the respiratory tract.
- They examine the baby, paying attention to the nature of breathing, the type of cough and the presence of nasal discharge. Look at the color skin, their cyanosis indicates oxygen deficiency. An important sign is shortness of breath, its occurrence indicates a number of pathologies.
- The doctor asks the parents if the child experiences short-term pauses in breathing during sleep. If this condition is typical, then this may indicate problems of a neurological nature.
- X-rays are prescribed to clarify the diagnosis if pneumonia or other lung pathologies are suspected. X-rays can be performed even on young children, if there are indications for this procedure. To reduce the level of radiation exposure, it is recommended that children be examined using digital devices.
- Examination using a bronchoscope. It is carried out for bronchitis and suspicion of a foreign body entering the bronchi. Using a bronchoscope, the foreign body is removed from the respiratory organs.
- Computed tomography is performed if there is a suspicion of oncological diseases. This method, although expensive, is the most accurate.
For children younger age bronchoscopy is performed under general anesthesia. This eliminates respiratory injuries during the examination.
The anatomical and physiological characteristics of the respiratory system in children differ from the respiratory system in adults. Children's respiratory organs continue to grow until approximately 18 years of age. Their size, vital capacity and weight increase.
The respiratory tract is divided into three sections: upper (nose, pharynx), middle (larynx, trachea, bronchi), lower (bronchioles, alveoli). By the time the child is born, they morphological structure is still imperfect, which is associated with functional features breathing. F Formation of the respiratory system ends on average before the age of 7, and then only their sizes increase. All airways in children are significantly smaller and have a narrower lumen than in adults. The mucous membrane is thinner, more delicate, and easily damaged. The glands are underdeveloped, the production of IgA and surfactant is insignificant. The submucosal layer is loose, contains a small amount of elastic and connective tissue elements, many are vascularized. Cartilaginous frame respiratory tract soft and pliable. This helps to reduce the barrier function of the mucous membrane, easier penetration of infectious and atopic agents into the bloodstream, and the emergence of preconditions for narrowing of the airways due to edema.
Another feature of the respiratory organs in children is that in young children they are small in size. The nasal passages are narrow, the shells are thick (the lower ones develop until the age of 4), so even minor hyperemia and swelling of the mucous membrane predetermine obstruction of the nasal passages, cause shortness of breath, and make sucking difficult. At the time of birth, only the maxillary sinuses are formed from the paranasal sinuses (they develop up to 7 years of life). The ethmoidal, sphenoidal and two frontal sinuses complete their development before the ages of 12, 15 and 20 years, respectively.
The nasolacrimal duct is short, located close to the corner of the eye, its valves are underdeveloped, so the infection easily penetrates from the nose into the conjunctival sac.
The pharynx is relatively wide and small. The Eustachian (auditory) tubes connecting the nasopharynx and the tympanic cavity are short, wide, straight and located horizontally, which facilitates the penetration of infection from the nose to the middle ear. In the pharynx there is the Waldeer-Pirogov lymphoid ring, which includes 6 tonsils: 2 palatine, 2 tubal, 1 nasopharyngeal and 1 lingual. When examining the oropharynx, the term “pharynx” is used. The pharynx is an anatomical formation, surrounded at the bottom by the root of the tongue, on the sides - by the palatine tonsils and brackets, at the top - soft palate and tongue, behind - back wall oropharynx, in front - the oral cavity.
The epiglottis in newborns is relatively short and wide, which may cause a functional narrowing of the entrance to the larynx and the occurrence of stridor breathing.
The larynx in children is located higher and longer than in adults, has a funnel-shaped shape with a clear narrowing in the subglottic space (4 mm in a newborn), which gradually expands (at 14 years of age up to 1 cm). The glottis is narrow, its muscles get tired easily. The vocal cords are thick, short, the mucous membrane is very tender, loose, significantly vascularized, rich in lymphoid tissue, easily leads to swelling of the submucosal membrane when respiratory infection and the occurrence of croup syndrome.
The trachea is relatively longer and wider, funnel-shaped, contains 15-20 cartilaginous rings, and is very mobile. The walls of the trachea are soft and collapse easily. The mucous membrane is tender, dry, and well vascularized.
Formed by the time of birth. The size of the bronchi increases rapidly in the 1st year of life and in teenage years. they are also formed by cartilaginous semirings, which in early childhood do not have endplates connected by a fibrous membrane. The cartilage of the bronchi is very elastic, soft, and moves easily. The bronchi in children are relatively wide; the right main bronchus is almost a direct continuation of the trachea, so foreign objects often end up in it. The smallest bronchi are characterized by absolute narrowness, which explains the occurrence of obstructive syndrome in young children. The mucous membrane of the large bronchi is covered with ciliated epithelium, which performs the function of cleansing the bronchi (mucociliary clearance). Incomplete myelination vagus nerve and underdevelopment of the respiratory muscles contribute to the absence of a cough reflex in young children or a very weak cough impulse. Mucus accumulated in small bronchi easily clogs them and leads to atelectasis and infection of the lung tissue.
Lungs in children, as in adults, have a segmental structure. The segments are separated from each other by thin connective tissue partitions. The main structural unit of the lung is the acinus, but its terminal bronchioles end not in a brush of alveoli, as in adults, but in a sac (sacculus), with the “lace” edges of which new alveoli are gradually formed, the number of which in newborns is 3 times less than in adults. With age, the diameter of each alveoli increases. At the same time, the vital capacity of the lungs increases. The interstitial tissue of the lungs is loose, rich in blood vessels, fiber, and contains little connective tissue and elastic fibers. In this regard, the lung tissue in children in the first years of life is more saturated with blood and less airy. Underdevelopment of the elastic framework leads to emphysema and atelectasis. The tendency to atelectasis also arises due to a deficiency of surfactant - a film that regulates surface alveolar tension and stabilizes the volume of terminal air spaces, i.e. alveoli Surfactant is synthesized by type II alveolocytes and appears in a fetus weighing at least 500-1000 g. The younger the child’s gestational age, the greater the surfactant deficiency. It is surfactant deficiency that forms the basis for insufficient expansion of the lungs in premature infants and the occurrence of respiratory distress syndrome.
The main functional physiological features of the respiratory organs in children are as follows. Children's breathing is frequent (which compensates for the small volume of breathing) and shallow. The frequency is higher, the younger the child (physiological dyspnea). A newborn breathes 40-50 times per minute, child aged 1 year - 35-30 times in 1 minute, 3 years old - 30-26 times in 1 minute, 7 years old - 20-25 times in 1 minute, 12 years old - 18-20 times in 1 minute, adults — 12-14 times in 1 minute. An acceleration or deceleration of breathing is noted when the respiratory rate deviates from the average by 30-40% or more. In newborns, breathing is irregular with short stops (apnea). The diaphragmatic type of breathing predominates, from 1-2 years of age it is mixed, from 7-8 years of age - in girls - thoracic, in boys - abdominal. The younger the child, the smaller the tidal volume of the lungs. Minute breathing volume also increases with age. However, this indicator relative to body weight in newborns is 2-3 times higher than in adults. The vital capacity of the lungs in children is significantly lower than in adults. Gas exchange in children is more intense due to the rich vascularization of the lungs, high speed blood circulation, high diffusion capabilities.
The formation of the tracheopulmonary system begins at the 3-4th week of embryonic development. Already by the 5th-6th week of embryo development, second-order branches appear and the formation of three lobes of the right lung and two lobes of the left lung is predetermined. During this period, the trunk of the pulmonary artery is formed, growing into the lungs along the primary bronchi.
In the embryo, at the 6-8th week of development, the main arterial and venous collectors of the lungs are formed. Within 3 months, the bronchial tree grows, segmental and subsegmental bronchi appear.
During the 11-12th week of development, areas of lung tissue are already present. They, together with the segmental bronchi, arteries and veins, form the embryonic segments of the lungs.
Rapid growth is observed between 4 and 6 months vascular system lungs.
In fetuses at 7 months, the lung tissue acquires the features of a porous canal structure; the future air spaces are filled with fluid, which is secreted by the cells lining the bronchi.
At 8-9 months of the intrauterine period, further development of the functional units of the lungs occurs.
The birth of a child requires the immediate functioning of the lungs; during this period, with the onset of breathing, significant changes occur in the airways, especially the respiratory part of the lungs. The formation of the respiratory surface in individual parts of the lungs occurs unevenly. For the management of the respiratory apparatus of the lungs, the condition and readiness of the surfactant film lining the lung surface are of great importance. Violation of the surface tension of the surfactant system leads to serious illnesses in young children.
In the first months of life, the child maintains the ratio of the length and width of the airways, like a fetus, when the trachea and bronchi are shorter and wider than in adults, and the small bronchi are narrower.
The pleura covering the lungs in a newborn baby is thicker, looser, contains villi and outgrowths, especially in the interlobar grooves. Pathological foci appear in these areas. Before the birth of a child, the lungs are prepared to perform the respiratory function, but individual components are in the development stage, the formation and maturation of the alveoli is rapidly proceeding, the small lumen of the muscular arteries is being reconstructed and the barrier function is being eliminated.
After three months of age, period II is distinguished.
- period of intensive growth of the pulmonary lobes (from 3 months to 3 years).
- final differentiation of all bronchopulmonary system(from 3 to 7 years).
Intensive growth of the trachea and bronchi occurs in the 1st–2nd year of life, which slows down in subsequent years, and the small bronchi grow intensively, and the branching angles of the bronchi also increase. The diameter of the alveoli increases, and the respiratory surface of the lungs doubles with age. In children under 8 months, the diameter of the alveoli is 0.06 mm, in 2 years - 0.12 mm, in 6 years - 0.2 mm, in 12 years - 0.25 mm.
In the first years of life, growth and differentiation of lung tissue elements and blood vessels occur. The ratio of the volumes of shares in individual segments is equalized. Already at 6-7 years of age, the lungs are a fully formed organ and are indistinguishable from the lungs of adults.
Features of the child's respiratory tract
The respiratory tract is divided into upper, which includes the nose, paranasal sinuses, pharynx, Eustachian tubes, and lower, which includes the larynx, trachea, bronchi.
The main function of breathing is to conduct air into the lungs, cleanse it of dust particles, and protect the lungs from the harmful effects of bacteria, viruses, and foreign particles. In addition, the airways warm and humidify the inhaled air.
The lungs are represented by small sacs that contain air. They connect with each other. The main function of the lungs is to absorb oxygen from the atmospheric air and release gases into the atmosphere, primarily acid coal.
Breathing mechanism. When inhaling, the diaphragm and chest muscles contract. Exhalation in older age occurs passively under the influence of elastic traction of the lungs. With bronchial obstruction, emphysema, and also in newborns, active inhalation occurs.
Normally, breathing is established at a frequency at which the volume of breathing is performed due to the minimum energy expenditure of the respiratory muscles. In newborn children, the respiratory rate is 30-40, in adults - 16-20 per minute.
The main carrier of oxygen is hemoglobin. In the pulmonary capillaries, oxygen binds to hemoglobin, forming oxyhemoglobin. In newborns, fetal hemoglobin predominates. On the first day of life, it is contained in the body about 70%, by the end of the 2nd week - 50%. Fetal hemoglobin has the ability to easily bind oxygen and difficult to release it to tissues. This helps the child in the presence of oxygen starvation.
Transport of carbon dioxide occurs in dissolved form; blood saturation with oxygen affects the content of carbon dioxide.
The respiratory function is closely related to the pulmonary circulation. This is a complex process.
During breathing, autoregulation is noted. When the lung stretches during inhalation, the inhalation center is inhibited, and exhalation is stimulated during exhalation. Deep breathing or forced inflation of the lungs leads to a reflex expansion of the bronchi and increases the tone of the respiratory muscles. When the lungs collapse and are compressed, the bronchi become narrowed.
The medulla oblongata contains the respiratory center, from where commands are sent to the respiratory muscles. The bronchi lengthen when you inhale, and shorten and narrow when you exhale.
The relationship between the functions of breathing and blood circulation appears from the moment the lungs expand during the first breath of a newborn, when both the alveoli and blood vessels expand.
Respiratory diseases in children may cause problems respiratory function and respiratory failure.
Features of the structure of a child's nose
In young children, the nasal passages are short, the nose is flattened due to an insufficiently developed facial skeleton. The nasal passages are narrower, the conchae are thickened. The nasal passages are fully formed only by the age of 4 years. The nasal cavity is relatively small in size. The mucous membrane is very loose and well supplied with blood vessels. The inflammatory process leads to the development of edema and, as a result, a reduction in the lumen of the nasal passages. Mucus often stagnates in the nasal passages. It can dry out, forming crusts.
When the nasal passages close, shortness of breath may occur; during this period, the child cannot suckle at the breast, becomes anxious, abandons the breast, and remains hungry. Children, due to difficulty in nasal breathing, begin to breathe through their mouths, their warming of the incoming air is disrupted and their susceptibility to colds increases.
If nasal breathing is impaired, there is a lack of discrimination of odors. This leads to loss of appetite, as well as a violation of the idea of external environment. Breathing through the nose is physiological, breathing through the mouth is a sign of nasal disease.
Accessory nasal cavities. The paranasal cavities, or sinuses, as they are called, are limited spaces filled with air. The maxillary (maxillary) sinuses are formed by the age of 7. Ethmoidal - by the age of 12, the frontal is fully formed by the age of 19.
Features of the nasolacrimal duct. The nasolacrimal duct is shorter than in adults, its valves are not sufficiently developed, and the outlet is located close to the corner of the eyelids. Due to these features, the infection quickly spreads from the nose to the conjunctival sac.
Features of the pharynxbaby
The pharynx in young children is relatively wide, the palatine tonsils are poorly developed, which explains the rare cases of sore throat in the first year of life. The tonsils are fully developed by the age of 4-5 years. By the end of the first year of life, almond tissue hyperplasias. But its barrier function at this age is very low. Overgrown almond tissue can be susceptible to infection, which is why diseases such as tonsillitis and adenoiditis occur.
The Eustachian tubes open into the nasopharynx and connect it to the middle ear. If an infection enters the middle ear from the nasopharynx, middle ear inflammation occurs.
Features of the larynxbaby
The larynx in children is funnel-shaped and is an extension of the pharynx. In children it is located higher than in adults and has a narrowing in the area cricoid cartilage, where the subglottic space is located. The glottis is formed by the vocal cords. They are short and thin, this is responsible for the child’s high, sonorous voice. The diameter of the larynx in a newborn in the area of the subglottic space is 4 mm, at 5-7 years old - 6-7 mm, by 14 years old - 1 cm. Features of the larynx in children are: its narrow lumen, many nerve receptors, easily occurring swelling of the submucosal layer, which can lead to severe breathing problems.
The thyroid cartilages form a more acute angle in boys over 3 years of age; from the age of 10, a typical male larynx is formed.
Features of the tracheababy
The trachea is a continuation of the larynx. It is wide and short, the tracheal frame consists of 14-16 cartilaginous rings, which are connected by a fibrous membrane instead of an elastic end plate in adults. The presence of a large number of muscle fibers in the membrane contributes to changes in its lumen.
Anatomically, the trachea of a newborn is located at the level of the IV cervical vertebra, and in an adult - at the level of the VI-VII cervical vertebra. In children, it gradually descends, as does its bifurcation, which is located in a newborn at the level of the third thoracic vertebra, in children 12 years old - at the level of the V-VI thoracic vertebra.
During physiological breathing, the lumen of the trachea changes. During coughing, it decreases by 1/3 of its transverse and longitudinal dimensions. The mucous membrane of the trachea is rich in glands that secrete a secretion that covers the surface of the trachea with a layer 5 microns thick.
The ciliated epithelium promotes the movement of mucus at a speed of 10-15 mm/min from the inside to the outside.
Features of the trachea in children contribute to the development of its inflammation - tracheitis, which is accompanied by a rough, low-timbre cough, reminiscent of a cough “like in a barrel”.
Features of the child's bronchial tree
The bronchi in children are formed at birth. Their mucous membrane is richly supplied with blood vessels and is covered with a layer of mucus, which moves at a speed of 0.25-1 cm/min. A feature of the bronchi in children is that elastic and muscle fibers are poorly developed.
The bronchial tree branches to the bronchi of the 21st order. With age, the number of branches and their distribution remain constant. The size of the bronchi changes rapidly in the first year of life and during puberty. They are based on cartilaginous semirings in early childhood. Bronchial cartilage is very elastic, pliable, soft and easily displaced. The right bronchus is wider than the left and is a continuation of the trachea, so foreign bodies are more often found in it.
After the birth of a child, a columnar epithelium with a ciliated apparatus is formed in the bronchi. With hyperemia of the bronchi and their swelling, their lumen sharply decreases (up to its complete closure).
Underdevelopment of the respiratory muscles contributes to a weak cough impulse in a small child, which can lead to blockage of small bronchi with mucus, and this, in turn, leads to infection of the lung tissue and disruption of the cleansing drainage function of the bronchi.
With age, as the bronchi grow, wide lumens of the bronchi appear, and the bronchial glands produce less viscous secretions, acute diseases of the bronchopulmonary system are less common compared to younger children.
Features of the lungsin children
The lungs in children, as in adults, are divided into lobes, and lobes into segments. The lungs have a lobular structure, the segments in the lungs are separated from each other by narrow grooves and partitions of connective tissue. The main structural unit is the alveoli. Their number in a newborn is 3 times less than in an adult. Alveoli begin to develop from 4-6 weeks of age, their formation occurs up to 8 years. After 8 years, children’s lungs increase due to their linear size, and at the same time, the respiratory surface of the lungs increases.
The following periods can be distinguished in the development of the lungs:
1) from birth to 2 years, when intensive growth of the alveoli occurs;
2) from 2 to 5 years, when elastic tissue intensively develops, bronchi with peribronchial inclusions of lung tissue are formed;
3) from 5 to 7 years, the functional abilities of the lungs are finally formed;
4) from 7 to 12 years, when a further increase in lung mass occurs due to the maturation of lung tissue.
Anatomically, the right lung consists of three lobes (upper, middle and lower). By 2 years, the sizes of the individual lobes correspond to each other, like in an adult.
In addition to the lobar division, segmental division is distinguished in the lungs: in the right lung there are 10 segments, in the left - 9.
The main function of the lungs is breathing. It is believed that 10,000 liters of air pass through the lungs daily. Oxygen absorbed from the inhaled air ensures the functioning of many organs and systems; the lungs take part in all types of metabolism.
The respiratory function of the lungs is carried out with the help of a biologically active substance - surfactant, which also has a bactericidal effect, preventing fluid from entering the pulmonary alveoli.
The lungs remove waste gases from the body.
A feature of the lungs in children is the immaturity of the alveoli; they have a small volume. This is compensated by increased breathing: the younger the child, the more shallow his breathing. The respiratory rate in a newborn is 60, in a teenager it is already 16-18 respiratory movements per minute. Lung development is completed by age 20.
A variety of diseases can impair the vital function of breathing in children. Due to the characteristics of aeration, drainage function and evacuation of secretions from the lungs, the inflammatory process is often localized in the lower lobe. This occurs in a supine state in infants due to insufficient drainage function. Paravisceral pneumonia most often occurs in the second segment of the upper lobe, as well as in the basal-posterior segment of the lower lobe. The middle lobe of the right lung may often be affected.
The following studies are of greatest diagnostic importance: X-ray, bronchological, determination of blood gas composition, blood pH, study of external respiration function, study of bronchial secretions, computed tomography.
By the frequency of breathing and its relationship with the pulse, the presence or absence of respiratory failure is judged (see Table 14).
The respiratory organs are several organs united into a single bronchopulmonary system. It consists of two sections: the respiratory tract, through which air passes; the lungs themselves. The respiratory tract is usually divided into: upper respiratory tract - nose, paranasal sinuses, pharynx, Eustachian tubes and some other formations; the lower respiratory tract - the larynx, the bronchial system from the largest bronchus in the body - the trachea to its smallest branches, which are usually called bronchioles. Functions of the respiratory tract organs in the body Respiratory tract: conduct air from the atmosphere to the lungs; clean air masses from dust pollution; protect the lungs from harmful influences (some bacteria, viruses, foreign particles, etc. settle on the bronchial mucosa and are then removed from the body); warm and humidify the inhaled air. The lungs themselves look like many small air-inflated sacs (alveoli), interconnected and similar to bunches of grapes. The main function of the lungs is the process of gas exchange, that is, the absorption of oxygen from the atmospheric air - a gas vital for the normal, harmonious operation of all body systems, as well as the release of exhaust gases and, above all, carbon dioxide into the atmosphere. All these essential functions respiratory organs can be seriously impaired in diseases of the bronchopulmonary system. The respiratory organs of children are different from the respiratory organs of adults. These structural features and functions of the bronchopulmonary system must be taken into account when carrying out hygienic, preventive and therapeutic measures in a child. In a newborn, the respiratory tract is narrow, the mobility of the chest is limited due to the weakness of the chest muscles. Breathing is frequent - 40-50 times per minute, its rhythm is unstable. With age, the frequency of respiratory movements decreases and is 30-35 times at the age of one year, at 3 years -25-30, and at 4-7 years old - 22-26 times per minute. The depth of breathing and pulmonary ventilation increase by 2-2.5 times. Hoc is " guard dog" respiratory tract. The nose is the first to take on the attack of all harmful external influences. The nose is the center of information about the state of the surrounding atmosphere. It has a complex internal configuration and performs various functions: air passes through it; It is in the nose that the inhaled air is heated and humidified to the parameters necessary for the internal environment of the body; the bulk of atmospheric pollution, microbes and viruses is primarily deposited on the nasal mucosa; In addition, the nose is an organ that provides the sense of smell, that is, it has the ability to sense odors. What provides the child normal breathing through the nose? Normal nasal breathing extremely important for children of any age. It is a barrier to infection entering the respiratory tract, and therefore to the occurrence of bronchopulmonary diseases. Well-warmed clean air is a guarantee of protection against colds. In addition, the sense of smell develops a child’s understanding of the external environment, is protective in nature, and forms an attitude towards food and appetite. Nasal breathing is physiologically correct breathing. It is necessary to ensure that the child breathes through his nose. Breathing through the mouth in the absence or severe difficulty of nasal breathing is always a sign of a nasal disease and requires special treatment. Features of the nose in children The nose in children has a number of features. The nasal cavity is relatively small. How smaller child, those smaller cavity nose The nasal passages are very narrow. The nasal mucosa is loose and well supplied with blood vessels, so any irritation or inflammation leads to rapid swelling and a sharp decrease in the lumen of the nasal passages, up to their complete obstruction. Nasal mucus, which is constantly produced by the mucous glands of the child’s nose, is quite thick. Mucus often stagnates in the nasal passages, dries out and leads to the formation of crusts, which, blocking the nasal passages, also contribute to impaired nasal breathing. At the same time, the child begins to “sniff” through his nose or breathe through his mouth. What can lead to impaired nasal breathing? Impaired breathing through the nose can cause shortness of breath and other respiratory disorders in children in the first months of life. In infants, the act of sucking and swallowing is disrupted, the baby begins to worry, abandons the breast, remains hungry, and if nasal breathing is absent for a long time, the child may even gain worse weight. Severe difficulty in nasal breathing leads to hypoxia - disruption of the oxygen supply to organs and tissues. Children who breathe poorly through their nose develop worse and lag behind their peers in mastering the school curriculum. Lack of nasal breathing can even lead to increased intracranial pressure and dysfunction of the central nervous system. At the same time, the child becomes restless and may complain of a headache. Some children have sleep disturbances. Children with impaired nasal breathing begin to breathe through their mouths, and cold air entering the respiratory tract easily leads to colds; such children get sick more often. And finally, nasal breathing disorder leads to a disturbance in the worldview. Children who do not breathe through their nose have a reduced quality of life. Paranasal sinuses Paranasal sinuses are limited air spaces of the facial skull, additional air reservoirs. In young children they are not sufficiently formed, so diseases such as sinusitis and sinusitis are extremely rare in children under the age of 1 year. At the same time, inflammatory diseases of the paranasal sinuses often bother children at an older age. It can be quite difficult to suspect that a child has inflammation of the paranasal sinuses, but you should pay attention to symptoms such as headache, fatigue, nasal congestion, and deterioration in school performance. Only a specialist can confirm the diagnosis, and the doctor often prescribes an X-ray examination. 33. Pharynx The pharynx in children is relatively large and wide. It contains a large amount of lymphoid tissue. The largest lymphoid formations are called tonsils. Tonsils and lymphoid tissue play a protective role in the body, forming the Waldeyer-Pirogov lymphoid ring (palatine, tubal, pharyngeal, lingual tonsils). The pharyngeal lymphoid ring protects the body from bacteria, viruses and performs other important functions. In young children, the tonsils are poorly developed, so a disease such as tonsillitis is rare in them, but colds, on the contrary, are extremely frequent. This is due to the relative vulnerability of the pharynx. Tonsils reach their maximum development by 4-5 years, and at this age children begin to suffer less from colds. Important formations such as the Eustachian tubes, which connect the middle ear (tympanum) to the pharynx, open into the nasopharynx. In children, the mouths of these tubes are short, which often causes inflammation of the middle ear, or otitis, with the development of a nasopharyngeal infection. Ear infections occur through swallowing, sneezing, or simply from a runny nose. The long course of otitis is associated precisely with inflammation of the Eustachian tubes. Prevention of middle ear inflammation in children is thorough treatment of any infection of the nose and pharynx. Larynx The larynx is a funnel-shaped structure next to the pharynx. When swallowing, it is covered by the epiglottis, which is like a lid that prevents food from entering the respiratory tract. The mucous membrane of the larynx is also richly supplied with blood vessels and lymphoid tissue. The opening in the larynx through which air passes is called the glottis. It is narrow, on the sides of the gap there are vocal cords - short, thin, so children's voices are high, ringing. Any irritation or inflammation can cause swelling vocal cords and subglottic space and lead to respiratory failure. Young children are more susceptible to these conditions than others. The inflammatory process in the larynx is called laryngitis. In addition, if the baby has underdevelopment of the epiglottis or a violation of its innervation, he may choke, he periodically experiences noisy breathing, which is called wheezing. As the child grows and develops, these phenomena gradually disappear. . In some children, breathing from birth may be noisy, accompanied by snoring and wheezing, but not in sleep, as sometimes happens in adults, but during wakefulness. In case of restlessness and crying, these noise phenomena uncharacteristic for a child may intensify. This is the so-called congenital stridor of the respiratory tract, it is caused by congenital weakness of the cartilages of the nose, larynx and epiglottis. Although there is no discharge from the nose, at first the parents think that the child has a runny nose, however, the applied treatment does not give the desired result - the baby’s breathing is equally accompanied by various sounds. Pay attention to how the child breathes in his sleep: if he breathes calmly, and before crying, he starts to “grunt” again, apparently, this is what we are talking about. Usually, by the age of two, as the cartilage tissue strengthens, stridor breathing itself disappears, but before this time, in the case of acute respiratory diseases, the breathing of a child who has such structural features of the upper respiratory tract can significantly worsen. A child suffering from stridor should be observed by a pediatrician, consult an ENT doctor and a neurologist. 34. Bronchi The lower respiratory tract is represented mainly by the trachea and bronchial tree. The trachea is the largest breathing tube in the body. In children, it is wide, short, elastic, easily displaced and compressed by any pathological formation. The trachea is strengthened by cartilaginous formations - 14-16 cartilaginous half-rings, which serve as a frame for this tube. Inflammation of the mucous membrane of the trachea is called tracheitis. This disease is very common in children. Tracheitis can be diagnosed by a characteristic, very rough, low-pitched cough. Usually parents say that the child coughs “like a pipe” or “like a barrel.” The bronchi are a whole system of air tubes that form the bronchial tree. The branching system of the bronchial tree is complex; it has 21 orders of bronchi - from the widest, which are called “main bronchi,” to their smallest branches, which are called bronchioles. Bronchial branches are entangled with blood and lymphatic vessels. Each previous branch of the bronchial tree is wider than the next, so the entire bronchial system resembles a tree turned upside down. The bronchi in children are relatively narrow, elastic, soft, and easily displaceable. The mucous membrane of the bronchi is rich in blood vessels, relatively dry, since the secretory apparatus of the bronchi is underdeveloped in children, and the secretion produced by the bronchial glands is relatively viscous. Any inflammatory disease or irritation of the respiratory tract in young children can lead to a sharp narrowing of the lumen of the bronchi due to swelling, mucus accumulation, compression and cause breathing problems. With age, the bronchi grow, their lumens become wider, the secretion produced by the bronchial glands becomes less viscous, and breathing disorders during various bronchopulmonary diseases are less common. Every parent should know that if signs of difficulty breathing occur in a child of any age, especially young children, urgent consultation with a doctor is necessary. The doctor will determine the cause of the breathing disorder and prescribe correct treatment. Self-medication is unacceptable, as it can lead to the most unpredictable consequences. Diseases of the bronchi are commonly called bronchitis.