What is the primary management strategy for pulmonary interstitial emphysema in extreme preterms?

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 severe pulmonary interstitial emphysema (PIE) in extreme preterm infants. 1

Pathophysiology and Prevention

PIE develops when air leaks from alveoli into the pulmonary interstitium, causing compression of adjacent functional lung tissue and compromising gas exchange. This condition is closely associated with respiratory distress syndrome (RDS) and mechanical ventilation in extremely preterm infants 2.

Prevention strategies include:

• Early CPAP with selective surfactant administration rather than routine intubation with prophylactic surfactant 1
• Lung-protective ventilation strategies with lower tidal volumes (3.5-5 mL/kg) if mechanical ventilation is necessary 1
• Early surfactant administration in infants with severe RDS requiring mechanical ventilation 1

Management Algorithm for Established PIE

First-line therapy:

1. High-frequency oscillatory ventilation (HFOV)
   • Use low oscillatory frequency (5-6 Hz) 1
   • Gradually reduce mean airway pressure as tolerated
   • HFOV has been shown to improve respiratory values (pH, PCO2, PO2) and decrease mean airway pressure in infants with PIE 3

For unilateral PIE:

1. Positional therapy

   • Position infant with the affected (emphysematous) lung dependent 4
   • Minimize chest physiotherapy and endotracheal suctioning 4

2. Selective bronchial intubation (if positional therapy fails)

   • For right-sided PIE: selective left main stem intubation 5
   • For left-sided PIE: selective right main stem intubation
   • This technique allows the affected lung to collapse while ventilating the unaffected lung

Volume-targeted ventilation considerations:

• Volume-targeted ventilation may reduce inflammatory response compared to pressure-limited ventilation 6
• Target tidal volumes of approximately 5 mL/kg if using this approach 6

Monitoring and Complications

Close monitoring is essential for:

• Oxygenation and ventilation parameters
• Hemodynamic stability (hypotension is a common complication) 3
• Bleeding diatheses 3

Potential complications include:

• Bronchopulmonary dysplasia
• Necrotizing tracheobronchitis
• Systemic/pulmonary hypoperfusion
• Prolonged hypoxia and respiratory acidosis 2

Special Considerations

Extremely low birth weight infants (<1000g) are at highest risk for PIE and require more aggressive management, including multisystem support for multiorgan dysfunction 1.

Persistent respiratory acidosis and high oxygen requirements are indications for escalation of therapy 1.

Pitfalls to Avoid

1. Excessive mean airway pressure - Can worsen air leaks and PIE
2. Delayed recognition - Early identification and intervention is critical
3. Aggressive chest physiotherapy - May worsen air leaks in established PIE
4. Inadequate ventilator adjustments - Failure to optimize ventilator settings based on patient response
5. Overlooking unilateral disease - Unilateral PIE may benefit from specific positioning or selective intubation strategies

The management of PIE in extreme preterm infants remains challenging, but with prompt recognition and appropriate ventilation strategies, outcomes can be improved.