What is the treatment for meconium aspiration syndrome?

Treatment of Meconium Aspiration Syndrome

The treatment of meconium aspiration syndrome (MAS) should focus on supportive respiratory care, with continuous positive airway pressure (CPAP) or conventional mechanical ventilation as first-line interventions for infants with respiratory distress, reserving more advanced therapies like inhaled nitric oxide for cases with persistent pulmonary hypertension. 1

Initial Management

For Infants with Meconium-Stained Amniotic Fluid (MSAF)

• At delivery:
  • A team skilled in tracheal intubation should be present at birth for infants with MSAF due to increased risk of requiring resuscitation 2
  • Vigorous infants: Allow to stay with mother and receive initial steps of newborn care; gentle clearing of meconium from mouth and nose with bulb syringe if necessary 3
  • Non-vigorous infants: Current guidelines no longer recommend routine tracheal intubation and suctioning 3
    • This represents a significant change from historical practice, as evidence suggests tracheal suctioning does not reduce MAS incidence or mortality 3
    • If attempted intubation is prolonged and unsuccessful, bag-mask ventilation should be initiated, particularly with persistent bradycardia 3

Respiratory Support

1. Oxygen therapy:

   • Use pulse oximetry to guide oxygen administration 3
   • For term infants: Initiate resuscitation with air (21% oxygen) and titrate as needed 3
   • For preterm infants (<35 weeks): Start with low oxygen concentration (21-30%) rather than high concentration (65-100%) 3

2. Ventilation strategies:

   • CPAP: Consider as initial respiratory support in spontaneously breathing infants with respiratory distress 1
   • Conventional mechanical ventilation: For infants with significant respiratory failure 1
   • PEEP: Beneficial for establishing functional residual capacity; can be maintained with self-inflating bag, flow-inflating bag, or T-piece 3

Advanced Therapies for Severe MAS

For infants with severe respiratory failure not responding to conventional ventilation:

1. Surfactant therapy: May be considered, though evidence is still evolving 4

2. Inhaled nitric oxide (iNO):

   • Indicated for hypoxic respiratory failure with evidence of pulmonary hypertension
   • FDA-approved for MAS with hypoxic respiratory failure 5
   • Reduces oxygenation index and increases PaO2 5
   • Monitoring: Methemoglobin levels should be monitored (typically remain below 1% at therapeutic doses of 5-20 ppm) 5

3. High-frequency ventilation: Consider for infants not responding to conventional ventilation 4

4. Extracorporeal membrane oxygenation (ECMO): Last resort for severe cases unresponsive to other therapies 4

Supportive Care

• Temperature regulation: Maintain normothermia and avoid hyperthermia 3
• Hemodynamic support: Monitor for and treat persistent pulmonary hypertension
• Fluid management and nutrition: Provide appropriate intravenous fluids while respiratory support is ongoing

Monitoring

• Continuous cardiorespiratory monitoring
• Regular blood gas analysis
• Pulse oximetry (preductal and postductal to assess for right-to-left shunting)
• Chest X-rays to assess lung condition and response to therapy

Prognosis

MAS has a case fatality rate of approximately 5% (up to 40% in severe cases), with potential long-term complications including pulmonary sequelae and neurodevelopmental issues 2. The introduction of innovative treatments like surfactant, high-frequency ventilation, inhaled nitric oxide, and ECMO has improved outcomes, but the majority of infants can be successfully managed with CPAP or conventional mechanical ventilation alone 1.

Common Pitfalls to Avoid

• Unnecessary suctioning: Routine oropharyngeal and nasopharyngeal suctioning is no longer recommended and may cause bradycardia 3
• Delayed ventilation: In non-vigorous infants, prolonged attempts at intubation for suctioning may delay necessary ventilation 3
• Oxygen toxicity: Avoid hyperoxemia by titrating oxygen to appropriate saturation targets 3
• Hyperthermia: Can worsen neurological outcomes and should be avoided 3