What is the primary management strategy for pulmonary interstitial emphysema (PIE) in extreme preterm infants?

Management of Pulmonary Interstitial Emphysema in Extreme Preterm Infants

High-frequency oscillatory ventilation (HFOV) with low oscillatory frequency (5-6 Hz) is the primary management strategy for pulmonary interstitial emphysema (PIE) in extreme preterm infants. 1

Pathophysiology and Prevention

PIE is a serious complication of respiratory distress syndrome in preterm infants, characterized by air leakage into the pulmonary interstitium. It can significantly worsen respiratory status and lead to increased morbidity and mortality. Prevention strategies include:

• Using early continuous positive airway pressure (CPAP) with selective surfactant administration rather than routine intubation with prophylactic surfactant 2
• Implementing lung-protective strategies with lower tidal volumes (3.5-5 mL/kg) if mechanical ventilation becomes necessary 2
• Early administration of surfactant in infants with severe RDS requiring mechanical ventilation 2

Management Algorithm for Established PIE

First-Line Therapy: HFOV with Low Frequency

• Initiate HFOV with frequency of 5-6 Hz and inspiratory time of 30% 1
• This approach provides prolonged expiratory time, allowing trapped air to escape
• Gradually reduce mean airway pressure as tolerated 2
• Monitor for physiological response, particularly improvement in oxygenation 1

For Unilateral PIE:

1. Positional therapy:

   • Position infant with the affected side dependent (lying on the affected side) 3
   • This can be achieved using a special splint while maintaining spontaneous breathing on High Flow Nasal Cannula (HFNC) 3
   • Complete resolution may be observed within 96 hours without requiring mechanical ventilation 3

2. If positional therapy fails:

   • Consider selective main stem intubation of the unaffected lung 4
   • For right-sided PIE, selective left main stem intubation can be performed, though technically challenging 4

For Bilateral or Severe PIE:

• Continue HFOV with low frequency settings
• If no improvement, consider therapeutic lung puncture to create and subsequently drain a pneumothorax 5
• This approach may help release tension in the overinflated lung before considering surgical interventions 5

Monitoring and Adjustment Parameters

• Closely monitor oxygenation (target SpO2 89-94%) 3
• Watch for persistent respiratory acidosis (pCO2 >55 mmHg) and increasing oxygen requirements as indicators for therapy escalation 2
• Track radiological changes to assess improvement
• Be vigilant for complications including hypotension and bleeding

Special Considerations

• Extremely low birth weight infants (<1000g) are at highest risk for PIE and may require more aggressive management 2
• PIE can develop even in infants on non-invasive respiratory support such as nasal CPAP 6
• Surgical interventions like lobectomy should be considered only after failure of less invasive approaches 5

Outcomes

With appropriate management using HFOV with low oscillatory frequency, significant improvement in oxygenation can be achieved, with reduced need for high mean airway pressures 1. In one study, 71% of infants with bilateral PIE and 100% of those with unilateral PIE survived with this approach 1.