Meconium Aspiration Syndrome (MAS)
Meconium staining of liquor.
Neonates born to mothers with thick or thin meconium stained liquor can aspirate meconium into lungs and develop respiratory distress known as MAS.
MAS happens when baby is stressed and gasps while still in womb or soon after delivery when taking first breaths of air.
MAS is respiratory distress in newborn baby caused by presence of meconium in tracheobronchial airways.
Aspiration of meconium stained amniotic fluid by fetus can happen during;
1. Antepartum period
2. Intrapartum period
This can result in airway obstruction, interference with alveolar gas exchange.
Thin meconium cause chemical pneumonitis (inflammation of lung tissue) and surfactant dysfunction (surfactant inactivation).
Thick meconium aspiration can block large and small airways causing area of atelectasis and emphysema.
Progress to develop air leak syndrome (pneumothorax)
Presence of atelectasis and emphysema cause ventilation perfusion mismatch.
Progress to Respiratory failure.
Clinical manifestations
MAS commonly usually occur in post mature and small for date babies.
1. MAS infant's have history of meconium- stained amniotic fluids (MASF).
2. Term or post term babies
3. Intrauterine growth retardation
4. Depressed at birth
5. Vernix, umbilical cord may meconium stained, depending how long infant exposed in utero.
6. Nail become stained after 6 hours of exposure.
Vernix after 12-24 hrs of exposure
Umbilical cord staining; thick; 15min and thin; 1 hours.
7. Respiratory distress mark with tachypnea and cyanosis.
8. Use of accessory muscles of respiration.
Evidenced by intercostal and subcostal retraction and abdominal breathing; often with grunting and nasal flaring.
Complications
Complications are;
Pneumothorax (leak syndrome)
Persistent pulmonary Hypertension
Pneumopericardium
Pneumomediastinum
Management
1. Babies born to mother with thick meconium stained liquor.
2. Oropharyngeal suction before delivery of shoulders and immediately after delivery endotracheal intubation and suctioning needs to be done to remove aspirated meconium and to prevent further respiration.
High oxygen concentration at high ventilatory rate provided using mechanical ventilors.
3. NICU (Neonatal intensive care unit)
1. Ventilatory support
2. Surfactant therapy
3. Inhaled nitric oxide (INO); for pulmonary vasodilation
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