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ANATOMICAL AND PHYSIOLOGICAL SPECIFICATIONS IN CHILDREN Development of the Lungs and its patho-physiological Consequences Anatomy of the Airways in Children ANATOMICAL AND PHYSIOLOGICAL SPECIFICATIONS IN CHILDREN Galic 2023: There is a large variety of anatomical and physiological features which make small children more susceptible to breathing disorders, with higher risks and greater differences in the course and characteristics of the disease. These characteristics can help understand the disease process and -states also during homeopathic treatment. Development of the Lungs and its patho-physiological Consequences Embryonal Period Until week seven- organogenesis, formation of larger airways Fetal Period Around week 17 of gestation - development of the main bronchial system, first acini form. Around week 26 - formation of lung periphery and first alveolar septa, differentiation of alveolar epithelium; beginning production of pulmonary surfactant. Premature Birth In preterm babies one of the possible complications is the lack of surfactant, causing insufficient surface tension of the alveolar membranes, which increases the risk of alveolar collapse. Newborns until 3rd year of Life At birth only 15%-20% of all the alveolae are mature (indicates lung volume). In this age-group obstruction of airways leads to a pathological respiratory resistance/distress much more quickly than at an older age. This has several reasons: First we have the much lower count of alveolae. Second the bronchi are much softer and therefore tend to collapse much more easily. Third is that collateral ventilation-paths are not yet developed sufficiently. For these reasons obstructive problems in the small bronchi can soon lead to a life-threatening situation. Because of the embryonic connection of the cervical dermatome C4 to the diaphragm, there are frequent cervical tensions as a concomitant symptom of breathing problems. Nurslings need 30% of their energy for breathing - adults at rest need only 5%! In nurslings the ribs run straightly transversal. Therefore they cannot rotate their ribs, so the breathing-movement depends mainly on the diaphragm. This is important because the intercostal muscle spasms in acute respiratory distress-syndrome are the main indicators for the evaluation of case-severity, next to the significant facial expression. Chest breathing starts with contraction of scalene muscles, the intercostal muscles follow. Therefore it is dangerous if the intercostal muscles cramp instead of actually contracting! Children above the age of three From here on the maturation of the lungs follows a more continuous path. From this point on the lungs have the shape and appearance of adults' lungs on a smaller scale. Anatomy of the Airways in Children (Ed. For clarification see also anatomic pictures, graphics - like e.g. Netters'Anatomy) Upper Airways The respiratory resistance in the nose is only half as pronounced in nurslings than it is later on. This is because the larynx stands up high, the laryngeal lid is soft, relatively big and is slightly turned in the direction of the palate, all which lead to the favoring of nasal breathing. Furthermore the tongue is relatively big, which also impedes mouth breathing. This may be a reason why some experienced homeopaths say that the symptom "Motion of alae nasi" is not homeopathically characteristic in small children. So during nose-obstruction - like in coryza - mouth-breathing is much less efficient in nurslings than in older children or adults and can lead to severe breathing difficulties. The narrowest part of the larynx in nurslings is at the cricoid cartilage, while in adults it is the glottis. Respiratory Muscles These include the diaphragm, the intercostal muscles, the scaleni and abdominal muscles. These are coordinated actively during the breathing cycle. (Details see below at Physiology.) In nurslings up to the first birthday the thorax plays only a small role for the process of breathing. The ribs are soft and flexible, they stand horizontally and therefore expansion of the thorax is hardly possible. With stronger and faster breathing the diaphragm moves so forcefully and quickly that the intercostal spaces are drawn in. The intercostal muscles do not have enough tension to keep the thorax stable. This thoracic excursion is called paradox breathing. The diaphragm is the most important respiratory muscle. In infants the diaphragm is 80% responsible for the process of breathing . Every impairment of its function - such as paralysis, bloated abdomen, hyperinflation, etc. - leads to high-grade dyspnea in nurslings! Shortly after birth babies mostly have type II muscle-fibers. Only after the first year of life does the number of type I muscle-fibers rise, type I fibers being more resistant to fatigue. The average oxygen consumption of the breathing muscles lies at 5% of the total body-requirement. This rises10-fold up to 50% in severe pneumonia! Physiological Breathing rest Position This is determined by the balance between the elastic retraction power of the lung tissue and the strength and flexibility of the thorax. For nurslings exhaling into the elastic equilibrium would be unfavorable, therefore their respiratory calm position is before thorax and lungs meet this equilibrium. The diaphragm stays tensed also during exhalation. The higher breathing frequency shortens the time for exhalation avoiding a complete emptying of the lungs. Above that the intra-thoracic pressure rises due to the narrowing of the laryngeal lid, leading to an increase of the end-expiratory residual volume. When the lungs mature between the first and second year of life these specialties fade out. Breathing Regulation Control variables are: pO2 and pCO2. Center of control is the respiratory center. Sensors are: Peripheral and central chemo- and mechano-receptors in the lungs. Effectors are the respiratory muscles. Respiratory Center This lies in the Medulla oblongata. This activates spinal moto-neurones for respiratory muscles. Simultaneously we find co-innervation from the cranial nerve nuclei for the breathing-synchronic changes in the tongue, larynx and bronchial muscles, influencing the muscle tonus. In nurslings the laryngeal chemo-reflex is important. Following suctioning of the airways during intubation, inhalation of milk or acidic vomiting, an arrest of breathing, bradycardia and increase of vascular resistance in the lungs are possible. Hypercapnia Increase of pCO2 leads to a rise of the tidal volume and breathing frequency. During sleep this leads to a wake-up-reaction, sometimes with a sudden jolt. Hypoxia In older children and adults a decrease of pO2 under 50-60mmHg leads - - to an increase of respiratory drive with an increase of respiratory minute volume. In premature born children and newborns this increase of breathing activity is only possible for a few minutes, since it takes so much high energy. At the same time the patient has an especially delayed expiration with a peculiar breathing sound, due to constriction of the laryngeal lid. Especially in premature and newborn babies this mechanism is a primary reason for frequent spells of apnea below a pO2 under 70 mmHg. Breathing during Sleep During REM-sleep breathing is intermittent with higher breathing frequency, lower tidal volume and more pauses of breathing. We also find paradox breathing movements and periodic breathing in addition to this mechanism in premature and newborn babies. During NON-REM-sleep breathing is regular, the frequency is lower and breathing volume is higher. In premature born babies we can observe frequent sighing, which activates less used or collapsed parts of the lungs. In the first 3 months of life the portion of NON-REM-sleep makes up to almost half of the total sleeping-time. Special forms of Breathing a. Periodic or Cheyne-Stokes-Breathing: Regular change between deep and flattening breathing with pauses up to 10 seconds in prematurely born children. This is still physiological within the first months of maturely born children. Adults only show this form of breathing during hypoxia. a. Biot's breathing: Short violent inspiration followed by slow expiration with pauses of breathing if pO2 decreases under 10mmHg. This is typical in newborns during asphyxia. A failure of gasping breathing is a possible explanation for Sudden-Infant-Death-Syndrome (SIDS). Generally breathing excursion is easily palpable with hands laid flatly on the thorax during the first year of life. Symmetry and synchronicity of breathing movements show us the state of function of the diaphragm. Vibrations can transfer easily to the surface of the thorax. ◄ DIFFERENTIAL DIAGNOSIS OF PNEUMONIA | ▲ | GUIDELINES FOR COMPREHENSIVE HOMEOPATHIC CASE-TAKING IN PNEUMONIA AND/OR PLEURISY ► |