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Infant Respiratory Distress Syndrome

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Overview

Also known as newborn respiratory distress syndrome (NRDS), surfactant deficiency disorder (SDD), surfactant deficient lung disease (SDLD), and previously known as hyaline membrane disease, infant respiratory distress syndrome (IRDS) describes difficulties with oxygenation and breathing due to inadequate surfactant production in the lungs.

Pathophysiology

Surfactant is produced by type II pneumocytes and lowers surface tension, preventing the alveoli from completely collapsing when exhaling. Most alveolar surfactant is made after 30 weeks and inadequate production increases the work required for breathing and oxygenation as the alveoli collapse and are difficult to expand.

As a result, hypoxia and carbon dioxide retention occur, and interstitial oedema can develop, reducing gas exchange even more.

Epidemiology

  • The risk of IRDS decreases with gestational age
    • A study in 2012 showed 98% of babies born at 24 weeks had IRDS and this dropped to less than 1% in babies born at 37 weeks

Risk Factors

  • Prematurity
  • Low birth weight
  • Male sex
  • Maternal diabetes – insulin is thought to reduce surfactant production
  • Caesarean section

Presentation

Features of respiratory distress occur from seconds to minutes after birth:

  • Tachypnoea
  • Grunting
  • Chest recessions
  • Nasal flaring
  • Cyanosis

As time goes on, IRDS rapidly worsens with fatigue, hypoxia, and apnoea.

Investigations

Overview

  • Chest X-ray:
    • May show a ground-glass appearance

Other test results include:

  • Blood gases:
    • May show respiratory acidosis and hypoxia
    • Metabolic acidosis may follow due to poor tissue oxygenation

Management

Prevention

Antenatal corticosteroids are given to people who are at risk of or confirmed to undergo preterm labour. This increases the production of surfactant and foetal lung maturation.

Acute management

Acute management of IRDS may involve:

  • Supplementary oxygen
  • Intubation and ventilation
  • Surfactant replacement therapy via an endotracheal tube

Complications

Acute complications include:

Chronic complications include:

  • Bronchopulmonary dysplasia
  • Retinopathy of prematurity
  • Hearing impairment

Prognosis

  • Mortality may be <10% in developed countries, but this significantly increases in low-income countries, sometimes nearing 100%

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