Management of Pulmonary Interstitial Emphysema in Extreme Preterm Infants
High-frequency oscillatory ventilation with low oscillatory frequency (5-6 Hz) is the most effective treatment strategy for severe pulmonary interstitial emphysema (PIE) in extreme preterm infants. 1
Pathophysiology and Prevention
PIE occurs when air leaks from the alveoli into the pulmonary interstitium due to alveolar overdistention, particularly in immature lungs. Prevention is critical:
- Use early CPAP with selective surfactant administration rather than routine intubation with prophylactic surfactant in preterm infants 2
- If mechanical ventilation is necessary, use lung-protective strategies with lower tidal volumes (3.5-5 mL/kg) 2
- Administer surfactant early in infants with severe RDS requiring mechanical ventilation 2
Diagnostic Approach
PIE presents radiographically as:
- Linear or cystic lucencies in the lung fields
- May be unilateral or bilateral
- Often associated with respiratory deterioration in previously stable infants
Management Algorithm for Established PIE
1. First-Line Approach
- High-frequency oscillatory ventilation (HFOV) with specific settings:
- Low oscillatory frequency (5-6 Hz)
- Inspiratory time 30%
- Gradually reduce mean airway pressure as tolerated 1
2. Positioning Strategies
- For unilateral PIE: Position with affected side dependent (down) to promote atelectasis and resolution 1, 3
- For bilateral PIE: Supine position with careful attention to ventilation parameters
3. Selective Intubation
- For severe unilateral disease: Consider selective intubation of the unaffected lung to allow collapse and healing of the affected lung 1, 3
4. Advanced Interventions for Refractory Cases
- Endobronchial balloon occlusion may be considered when conventional therapies fail and selective intubation is not possible 3
Monitoring and Adjustments
- Monitor oxygenation closely - improvement is typically seen within 4 hours of transitioning to low-frequency HFOV 1
- Serial chest radiographs to assess resolution
- Gradual weaning of ventilatory support as PIE resolves
- Be aware that functional abnormalities may persist even after radiological resolution 4
Outcomes and Prognosis
With appropriate management, survival rates can reach:
- 71% for bilateral PIE cases
- Nearly 100% for unilateral PIE cases 1
Cautions and Pitfalls
- Avoid excessive mean airway pressures which can worsen air leaks
- Be vigilant for complications including:
- Hypotension requiring inotropic support
- Bleeding diatheses
- Bronchopulmonary dysplasia
- Necrotizing tracheobronchitis 5
- Remember that functional abnormalities may persist even after radiological resolution of PIE 4
Special Considerations
- Extremely low birth weight infants (<1000g) are at highest risk and may require more aggressive management
- Persistent respiratory acidosis and high oxygen requirements are indications for escalation of therapy
- Multisystem support is often necessary as respiratory insufficiency may be part of multiorgan dysfunction 2
Early recognition and prompt implementation of appropriate ventilation strategies are crucial for improving outcomes in extreme preterm infants with PIE.