Physiologicoanatomical Peculiarities of the Respiratory System of Newborns

The basic tips you need to know in the physiologicoanatomical peculiarities of the respiratory system of newborns is the peculiarities in the nose, sinuses, pharynx, larynx, trachea, bronchi and the lungs.

kerdi membrane

The Peculiarities of the nose at the neonate
• The nose is particularly made up of cartilage
• The nasal meatuses are narrow
• There is no inferior nasal meatus (until 4 years)
• Undeveloped submucosal membrane (until 8-9 years)

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The peculiarities of sinuses in children
• The maxillary sinus is usually present at birth
• The frontal sinuses begin to develop in early infancy
• The ethmoid and sphenoid sinuses develop later in childhood

The peculiarities of the pharynx at the neonate
• The pharynx is relatively small and narrow
• The auditory tubes are small, wide, straight and horizontal

The peculiarities of the larynx at the neonate
• The larynx is funnel-shaped (in the adult it is relatively round)
• It is relatively long
• The cricoid's cartilage descendents from the level of the fourth cervical vertebra in the infant to that of the sixth in the adult
• The fissure of glottis is narrow and its muscles fatigue soon, vocal ligaments and mucous membrane are very tender and well blood-supplied
• Vocal ligament are relatively short

The peculiarities of the trachea at the neonate
• The length of the trachea is relatively larger (about 4cm unlike in Adult which is 7cm) and wide
• It is composed of 15-17 cartilage rings (the amount does not increase)
• The bifurcation of the trachea lies opposite the third thoracic vertebra in infant and descends to a position opposite the fourth vertebra in the adult
• Mucus membrane is soft, well-blood supplied, but sometime dry,
• It can collapse easily.

The peculiarities of the bronchi at the neonate
• In young children the bronchi are relatively wide
• The right bronchus is a straight continuation of the trachea
• The muscle and elastic fibers are undeveloped
• The bronchi are well blood supplied
• The lobules and segmented bronchus are narrow

The functions of the bronchus
• The ciliated mucus membrane "sweeps" out dust particles
• Transfer of gases into the lungs
• Immunologic function

The functions of the Lung are
• The main function of the lungs is the exchange of Oxygen and carbon dioxide
• To produce surfactant

The peculiarities of the lungs at the neonate
• Size of alveoli is smaller than in adult
• Quantity of alveoli is relatively less than in adult.

Considerable or obvious deviations from these peculiarities indicate abnormalities or further clinical examination.

Physiologicoanatomical Peculiarities of the Respiratory System of Newborns

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Definition of Hyaline Membrane Disease Respiratory Distress Syndrome (RDS I)

Also known as idiopathic respiratory distress syndrome (RDS) Type I, hyaline membrane disease is an acute disorder found primarily in preterm infants at birth of shortly after birth, most often in infants under 32 week's gestation who weigh less than 3 lb, 4 oz (1,500 g). Roughly 60% of infants born before 29 week's gestation develop RDS.

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Fetal lung development and surfactant production are necessary for normal respiratory function; lung development and surfactant production varies with each infant. The preterm infant is born before sufficient surfactant develops or with a lack of mature surfactant production. Surfactant, a lipoprotein that lines the alveoli, prevents alveolar collapse and decreases the work of respiration by decreasing surface tension. With a deficiency, surface tension increases, causing alveolar collapse and decreased lung compliance, which affects alveolar ventilation, leading to hypoxemia and hypercapnia with respiratory acidosis. The reduction in ventilation leads to a poor ventilation and perfusion ratio of the pulmonary circulation, resulting in hypoxemia. Tissue hypoxia and metabolic acidosis result with associated atelectasis and respiratory failure progression.

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RDS, the leading cause of mortality and morbidity in preterm infants, usually lasts 3 to 5 days. The prognosis is poor if prolonged ventilator support is needed; death is less likely after 3 days of treatment.

This plan focuses on care of the infant at risk for or with RDS and on all the associated respiratory support that may be needed.

Etiology and precipitating factors
• prematurely with immature lungs (ranges less than 32 to 35 weeks' gestation) and absence, alteration, or deficiency of pulmonary surfactants
• cesarean delivery of preterm infant
• decreased oxygen present in the fetus or at birth in term or preterm infants

Physical findings

Maternal history
• disorder such as diabetes mellitus
• condition such as placental bleeding
• type and intrapartal stress

Infant status at birth
• prematurely, gestational age
• apart score noting asphyxia
• cesarean delivery of preterm infant

Cardiovascular
• bradycardia (less than 100 beats/minute) with severe hypoxemia

Integumentary
• pallor caused by peripheral vasoconstriction
• pitting edema in hands and feet within 24 hours
• mottling

Neurologic
• immobility, motionlessness; flaccidity
• decreased body temperature

Cardiovascular
• systolic murmur
• heart rate within normal limits

Pulmonary
• tachypnea (more than 60 breaths/minute' may be 80 to 100)
• expiratory grunting or whining
• nasal flaring
• intercostals, suprasternal, or substernal retractions
• cyanosis (circumoral followed by central) related to percentage of destructed hemoglobin
• Decreased breath sounds, crackles, apneic episodes.

Behavioral findings
• lethargy

Diagnostic studies
• serial chest X-rays - reveal clouded appearance with grainy look, areas of density or of atelectasis, and elevated diaphragm with over distended alveolar ducts
• air bronchograms - reveal ventilation of the airway, not the alveoli

Laboratory data
• lung profiles - to determine lung maturity; done on amniotic fluid (for fetuses predisposed to RDS):
o lecithin/sphingomyelin (L/S) ratio of
2:1 or more indicates pulmonary maturity
- 1:1 before 35 weeks' gestation (L: 6 to 9 mg/dl,
S: 4 to 6 mg/dl)
- 4:1 after 35 weeks' gestation (L: 15 to 21 mg/dl,
S: 4 to 6 mg/dl)
o Phosphatidylglycerol: elevated at 35 weeks' gestation
o Phosphatidylinositol level

• Arterial blood gas (ABG) levels - PaO2 less than 50 mm Hg while on 100% oxygen, PaCO2 less than 60 mm Hg, oxygen saturation 92% to 94%, pH 7.31 to7.45
• Potassium levels - increase as potassium is released from injured alveolar cells

Definition of Hyaline Membrane Disease Respiratory Distress Syndrome (RDS I)

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