(1) Anatomical characteristics of infant respiratory system
The respiratory system includes a series of organs that inhale oxygen, discharge carbon dioxide, and complete gas exchange. Specifically, the respiratory system includes the respiratory tract for gas transmission and the lung for gas exchange.
The infant respiratory system consists of the nose, lacrimal duct and eustachian tube, larynx, trachea and bronchi, lungs, and thorax.
The infant’s nasal cavity is relatively short and narrow, and the nasal mucosa is soft and rich in blood vessels. When infected, the nasal mucosa is congested and swollen, which makes the nasal cavity narrow or even occluded. Babies cannot breathe with their mouth open, and nasal congestion can cause restlessness, difficulty breathing, and resistance to sucking.
2. Lacrimal duct and Eustachian tube
The infant’s nasolacrimal duct is short, the opening is close to the inner abutment, and its valve is underdeveloped, so nasal infections often invade the conjunctival sac and cause fire. The infant’s eustachian tube is wide, straight and short, and horizontal, while the opening of the nasopharyngeal cavity is lower. Therefore, inflammation of the pharynx can easily invade the middle ear and cause otitis media.
Babies have a narrow larynx, narrow glottis, soft cartilage, fragile mucosa, loose submucosal tissues, and abundant lymphatic tissue and blood vessels. Mild inflammation is also prone to narrow larynx and difficulty breathing and hoarseness. In severe cases, it can occur. Burrow.
4. Trachea and bronchus
The right bronchus of the baby is straighter, and foreign bodies are easier to enter. The lumen of trachea and bronchus is narrower than adults, cartilage is soft, lack of elastic tissue, mucosal plate is weak, and there are abundant blood vessels. The mucous glands are drier due to insufficient secretion, the mucociliary movement is poor, and the microorganisms and mucus are not well removed, and infection is prone to; inflammation causes the lumen to become narrower and cause breathing difficulties.
In the neonatal period, the wall layers of trachea, bronchi and bronchiole are relatively thin, with less muscle and nodular tissues. Later development is mainly due to the increase of muscle tissue to thicken the tube wall. Infant lungs are rich in connective tissue, poorly developed elastic tissue, rich in blood vessels and more blood, less gas, and the lung interstitium is developed vigorously, and the number of alveoli is small. Therefore, it is easy to be blocked by mucus and cause inflammation when infected, and it is easy to develop lungs. Flatulence, emphysema, falling back of the lung, etc.
The breast gallery of the baby is short, the anterior and posterior diameter is relatively long, it is cylindrical, and the ribs are horizontal. The chest cavity is small, the lungs are relatively large, almost filling the entire chest cavity, coupled with poor respiratory muscle development, poor muscle tension, insufficient thoracic movement during breathing, restricted lung expansion, and insufficient gas exchange. When breathing is difficult, you can't deepen your breathing, you can only increase the number of breaths to improve the lack of gas exchange in the lungs, but the benefits are not large, and the symptoms of hypoxia are prone to occur. Later, as I grow older, I start to stand and walk, the diaphragm decreases (down to the fifth rib after 3 years of age), the ribs gradually tilt, and the shape of the chest gradually approaches an adult.
(2) Physiological characteristics of infant respiratory system
1. The respiratory tract has the function of regulating temperature
The mucosa of the upper respiratory tract has a rich capillary network, which can warm the inhaled air close to body temperature when breathing, and can also be humidified and then enter the lower respiratory tract.
2. Mucocilium has a clearing effect
The mucosal epithelial cells above the bronchus have a ciliary circulatory system, which has a clearing function, which is very important to prevent infection and maintain normal functions. In addition, inhalation of microorganisms or particles can be used to swing out of the body.
3. Characteristics of lung retraction force
Infant lung retraction force and thoracic retraction force are smaller than adults, so the lungs are in a state of expansion. If the oxygen demand increases, due to less buffered air, insufficient ventilation is likely to occur.