- Clinical science
Neonatal respiratory distress syndrome (NRDS), or surfactant deficiency disorder, is a lung disorder in infants that is caused by a deficiency of pulmonary surfactant. It is most common in preterm infants, with the incidence and severity decreasing with gestational age. Surfactant deficiency causes the alveoli to collapse, resulting in impaired blood gas exchange. Symptoms manifest shortly after birth and include tachypnea, tachycardia, increased breathing effort, and/or cyanosis. The diagnosis is suspected based on clinical features and confirmed by evaluating the extent of atelectasis via chest x-ray. Blood gases show respiratory and metabolic acidosis, as well as hypoxia. Treatment primarily involves emergent resuscitative measures, which include nasal CPAP and stabilization of blood sugar levels and electrolytes. Additionally, intratracheal surfactant is administered if ventilation alone is not successful. Most cases resolve within 3–5 days of treatment. However, complications like hypoxemia, tension pneumothorax, bronchopulmonary dysplasia, sepsis, and neonatal death may still occur. NRDS can be prevented by administering antenatal glucocorticoids to the mother if premature delivery is expected.
- Surfactant: Pulmonary surfactant is a mixture of phospholipids and proteins produced by lamellar bodies of . These phospholipids reduce alveolar surface tension and thereby prevent the alveoli from collapsing.
Surfactant deficiency: → little or no reduction of alveolar surface tension → reduced pulmonary unfolding → atelectasis → decreased lung compliance and functional residual capacity → hypoxemia and hypercapnia
- Hypoxemia and hypercapnia → vasoconstriction of the pulmonary vessels (hypoxic vasoconstriction) and acidotic metabolism → intrapulmonary right-to-left-shunt → increased permeability due to alveolar epithelial damage → fibrinous exudation within the alveoli → development of hyaline membranes in the lungs (hyaline membrane disease)
- History of premature birth
- Onset of symptoms: usually presents immediately after birth
Signs of increased breathing effort
- Nasal flaring and moderate to severe subcostal/intercostal and jugular retractions
- Typical expiratory “grunting”
- Auscultation: decreased breath sounds
- Cyanosis due to peripheral hypoxic vasoconstriction
- Chest x-ray: diffuse, fine, reticulogranular (ground-glass) densities, with low lung volumes and air bronchograms
- Blood gas analysis
- Prenatal testing for NRDS
- Microscopic findings
- Lung hypoplasia
Transient tachypnea of the newborn (wet lung disease)
- Reversible respiratory disorder
- Most commonly occurring in full-term neonates born by cesarean section in which the lungs are still filled with fluid
- Diffuse crackles are heard on exam
- X-ray shows fluid in the lung fissures and increased lung volumes
- Therapy should focus on supportive care (e.g., supplemental oxygen, neutral thermal environment, adequate nutrition)
- Meconium aspiration syndrome: Neonates with meconium aspiration are usually post-term rather than preterm children.
- Neonatal pneumonia
The differential diagnoses listed here are not exhaustive.
- Endotracheal administration of artificial surfactant within 2 hours postpartum
- Supportive measures: IV fluid replacement; stabilization of blood sugar levels and electrolytes
- Definition: chronic lung disease primarily found in premature infants exposed to prolonged mechanical ventilation and oxygen therapy for neonatal RDS
- Etiology: immature lung with exposure to ventilation → barotrauma, oxygen toxicity, inflammation
- Clinical features
- Therapy: controlled oxygenation; , high-calorie food, diuretics, consider glucocorticoids
We list the most important complications. The selection is not exhaustive.
- Neonatal RDS has a case fatality rate of 30% if not treated.
- Most cases that have been diagnosed and promptly treated resolve within 3–5 days of treatment.