Inside the uterus, the fetus gets oxygen from gas exchange through the placenta. After the baby is born, the gas exchange must pass through the lungs. Stimulation of the first respiratory movement occurs because of the mechanical pressure of the thorax when passing through the birth canal (mechanical stimulation). Also, the decrease in Pa O2 and the increase in Pa CO2 triggers the chemoreceptors located in the sinus carotic (chemical stimulation). Even, cold stimulation in the face and temperature changes in the uterus ( sensory stimulation) and breeding deflationary defect.
The first breathing in a normal baby occurs within the first 30 minutes after birth. The baby’s first attempt is to maintain the pressure of the alveoli. Also, their attempt is to the presence of surfactants which by inhaling and exhaling. It means exhaling by moaning so that the air blocked inside. Respiration in neonates often has diaphragmatic and abdominal breathing, while the frequency and depth are not regular. When the surfactant decreases, the alveoli collapse and the lungs are stiff so atelectasis occurs. In anoxic conditions, the neonate can still maintain its life due to anaerobic metabolism.
This change in the respiratory system begins with the development of the lung organs with the development of bronchial structures, bronchioles, and alveoli. These are formed during the pregnancy process so that they can determine the maturation process in the respiratory system. The process of changing newborns is in terms of breathing. Moreover, it can be influenced by a state of hypoxia at the end of labor and physical (environmental) stimulation that stimulates the respiratory center of the medulla oblongata in the brain.
Also, there is also pressure in the chest cavity due to pulmonary compression during labor. Thus stimulating the entry of air into the lungs, then the emergence of breathing can occur due to the interaction of the respiratory system itself (with the cardiovascular system and central nervous system). The presence of surfactants and respiration efforts in breathing can be useful for removing fluid in the lungs and developing lung alveolar tissue to function. These surfactants can reduce lung surface pressure and help stabilize the alveolar duct to prevent collapse.
The strength of the breathing muscles and the ability of the diaphragm to move, directly affect the strength of each inspiration and inspiration in newborns. Healthy newborns set their breathing efforts to achieve the right balance between oxygen, carbon dioxide, and functional residual capacity. Breath frequency in normal newborns is 40 times per minute with a range of 30-60 times per minute (diaphragmatic and abdominal breathing). If the frequency is consistently more than 60 times per minute, with or without a nostril, snoring sound or chest wall retraction, clearly an abnormal response at 2 hours after birth.
Stimulation of the first respiratory movement occurs due to the following things:
- Mechanical pressure from the piston when through the birth canal (mechanical stimulation)
- A decrease in PaO2 and an increase in PaO2 stimulating chemoreceptors located in the carotid sinus (mechanical stimulation).
- Cold stimulation in the face and temperature changes in the uterine greetings (sensory stimulation).
- Reflex deflation of Breur’s Day.
The wall of the alveoli is joined by the surface tension of the thick liquid that overlaps it. More than 25 mmHg of negative pressure is needed to counteract the surface tension and to open the alveoli for the first time. But once opening the alveoli, further breathing can be affected by relatively weak breathing movements. Fortunately, the breathing of a newborn is very strong for the first time, it is usually able to cause a negative pressure of 50 mmHg in the intrapleural space.
• Lung development
The lungs come from growing points that emerge from branching pharynx and branch off again to structure the bronchial branching. This process continues gradually around 8 years until the number of bronchi and alveoli will fully develop, even though the fetus shows breath movements during the second trimester and third trimester.
• Beginning of breath
The factors that play a role in the baby’s first breath stimulation are:
1. Hypoxia at the end of labor and physical stimuli outside the uterine environment. This stimulates the respiratory center in the brain.
2. The pressure to the chest cavity, which occurs due to compression of the lungs during labor. This mechanically stimulates the entry of air into the lungs. The interaction between the respiratory, cardiovascular, and central nervous system causes regular and continuous breathing and pulses needed for life.
3. Stockpiling of carbon dioxide (CO2)
The levels of CO2 increase in the blood and will stimulate breathing. Reduced O2 will reduce fetal breathing movements, but conversely, the increase in CO2 will increase the frequency and level of fetal breathing movements.
4. Temperature changes. Cold conditions will stimulate breathing.
• Surfactants and respiratory efforts to breathe
A baby’s first respiratory effort serves to:
o Removing fluid in the lungs
o Developing lung alveolar tissue for the first time
For the alveolus to function, there must be enough surfactant (lecithin/sphingomyelin) and blood flow to the lungs. Surfactant production starts at 20 weeks of pregnancy. Then, it increases until the matured lungs (about 30-34 weeks of pregnancy). The function of surfactants is to minimize the pressure of the lung surface and help stabilize the alveolar wall so that it does not collapse at the end of breathing. The absence of surfactants causes the alveoli to collapse at the end of breathing that causes difficulty breathing. This increased need requires more use of oxygen and glucose. These increases cause stress in previously disturbed babies.
• From liquid to air
A preterm baby normally has fluid in his lungs. If the baby passes through the birth canal during labor, one until three of this fluid squeezed out of the lungs. An SC-born baby loses the advantage of compression of the chest cavity and can suffer from wet lungs for a longer period. With the first few breaths, the air filled the newborn’s trachea and bronchus. The remaining fluid in the lungs is removed from the lungs and absorbed by lymph and blood vessels.
• The function of the respiratory system and its relation to cardiovascular function
Adequate oxygenation is a very important factor in maintaining adequate air exchange. If hypoxia is found, the pulmonary arteries will experience vasoconstriction. If this happens, it means that there are no open blood vessels to receive oxygen in the alveoli, resulting in a decrease in tissue oxygen, which will worsen hypoxia. Increased lung blood will facilitate gas exchange in the alveoli, help remove lung fluid and stimulate changes in fetal circulation into the outer circulation of the uterus.