Meconium Aspiration Syndrome

 

• Most common cause of neonatal respiratory distress in full-term/postmature infants
  • Hyaline membrane disease most common cause in premature infants
• Etiology
  • Fetal circulatory accidents/placental insufficiency /postmaturity result in perinatal hypoxia and fetal distress
  • Meconium defecated in utero triggered by vagal response
  •  
• Pathogenesis
  • Meconium products produce bronchial obstruction and air-trapping
  • Chemical pneumonitis
• Incidence
  • 10% of all deliveries have meconium-stained amniotic fluid
  • 1% of all deliveries have respiratory distress
• Clinical findings
  • Cyanosis (rare)
  • Large infant
• Imaging findings
  • Bilateral diffuse grossly patchy opacities (atelectasis and consolidation)
  • Hyperinflation of lungs
  • Areas of emphysema (air-trapping)
  • Spontaneous pneumothorax and pneumomediastinum
    • 25% requiring no therapy
  • Small pleural effusions (20%)
  • No air bronchograms
  • Rapid clearing usually within 48 hours

Frontal chest shows large, ropey and strand-like densities in
a post-mature infant consistent with Meconium Aspiration Syndrome

• Treatment
  • Supportive
    • Antibiotics and oxygen
    • ECMO can be used
• Complications
  • Morbidity from anoxic brain damage is high