Respiratory distress syndrome

Respiratory distress syndrome (RDS) is a relatively common condition resulting from insufficient production of surfactant that occurs in preterm neonates. 

On imaging, the condition generally presents as bilateral and relatively symmetric diffuse ground glass lungs with low volumes and a bell-shaped thorax.

RDS is also known as hyaline membrane disease (not favored as reflects non-specific histological findings), neonatal respiratory distress syndrome, lung disease of prematurity (both non-specific terms), or as some authors prefer surfactant-deficiency disorder 2

The incidence is estimated at 6 per 1000 births 2.  Uncommon after 36 weeks' gestation due to development of pneumocyte surfactant production around 35 weeks5.

Respiratory distress presents in the first few hours of life in a premature baby. Signs include tachypnea, expiratory grunting, and nasal flaring. The infant may or may not be cyanosed. Substernal and intercostal retractions may be evident. 

Risk factors include maternal diabetes, greater prematurity, perinatal asphyxia and multiple gestations.

Associated abnormalities are those that can occur in prematurity: germinal matrix hemorrhage, necrotizing enterocolitis, patent ductus arteriosus, delayed developmental milestones, hypothermia and hypoglycemia.

Immature type II pneumocytes cannot produce surfactant. The lack of surfactant increases the surface tension in alveoli causing collapse. Patients have a decreased lecithin to sphingomyelin ratio. Damaged cells, necrotic cells, and mucus line the alveoli.

Although most cases are related to prematurity alone, rarely patients may have genetic disorders of surfactant production and can present in a similar clinical and radiological manner 6.

  • typically gives diffuse ground glass lungs with low volumes and a bell-shaped thorax
  • often bilateral and symmetrical
  • air bronchograms may be evident
  • lung whiteout in severe cases
  • hyperinflation (in a non-ventilated patient) excludes the diagnosis
  • may show hyperinflation if the patient is intubated

RDS can be safely excluded if the neonate has a normal chest radiograph at six hours after birth. 

If treated with surfactant therapy there may be asymmetric improvement.

Exogenous surfactant administration. Supportive oxygen therapy.


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Article information

rID: 1467
Synonyms or Alternate Spellings:
  • Surfactant deficiency disease
  • Respiratory distress syndrome (RDS)
  • HMD
  • Infantile respiratory distress syndrome
  • RDS
  • Hyaline membrane disease
  • Surfactant deficiency disorder

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