Surfactant Therapy in Neonates
Introduction
Surfactant therapy is a cornerstone in managing respiratory distress syndrome (RDS), also known as hyaline membrane disease (HMD), in preterm neonates. Surfactants reduce alveolar surface tension, preventing atelectasis and improving oxygenation and ventilation.
Pathophysiology of RDS
- Cause: Surfactant deficiency in immature lungs.
- Clinical Features: Respiratory distress (tachypnea, grunting, retractions, cyanosis), typical chest X-ray findings (ground-glass appearance, air bronchograms).
- Role of Surfactant: Surfactant stabilizes alveoli by lowering surface tension, enhancing gas exchange.
Types of Surfactants Used in Neonates
- Natural Surfactants: Derived from bovine or porcine sources (e.g., Beractant, Poractant alfa).
- Synthetic Surfactants: Fully synthesized surfactants, though less commonly used (e.g., Lucinactant).
- Advantages of Natural Surfactants: Better outcomes due to similarity with human surfactant proteins.
Indications for Surfactant Therapy
- Established RDS in preterm neonates (<34 weeks gestation).
- Prophylaxis in high-risk preterm neonates (<28 weeks gestation or those with low surfactant levels).
- Neonates with secondary surfactant deficiency (e.g., meconium aspiration syndrome, pulmonary hemorrhage, sepsis).
- Rescue therapy in severe respiratory failure (persistent hypoxemia or acidosis despite ventilation).
Surfactant Administration Techniques
- INSURE (Intubate-Surfactant-Extubate):
- Indicated in neonates with moderate RDS.
- Process: Intubation → Surfactant administration → Immediate extubation to CPAP.
- Benefits: Reduced duration of mechanical ventilation, lower risk of chronic lung disease.
- Minimally Invasive Surfactant Therapy (MIST):
- Also called LISA (Less Invasive Surfactant Administration).
- Surfactant delivered via thin catheter under CPAP without intubation.
- Advantages: Reduced trauma, avoids ventilator-induced lung injury.
- Key studies: Highlighted in recent advancements (2021/1, 2022/2).
- Bolus Delivery: Traditional method with endotracheal intubation and mechanical ventilation.
Evidence-Based Guidelines for Surfactant Use
- Timing:
- Prophylactic surfactant within 30 minutes of birth for very preterm infants (<28 weeks).
- Early rescue therapy within 2-4 hours for those with moderate-to-severe RDS.
- Dosing:
- Depends on the type of surfactant (e.g., Poractant alfa: 200 mg/kg initially; Beractant: 100 mg/kg initially).
- Re-dosing:
- Required if RDS persists or recurs after initial therapy (up to 2-3 doses).
Minimally Invasive Surfactant Therapy (MIST)
- Recent advancements emphasize non-invasive administration of surfactants to reduce complications. Studies suggest MIST/LISA improves outcomes in neonates by:
- Minimizing barotrauma and volutrauma.
- Preventing bronchopulmonary dysplasia.
- Challenges: Requires skilled operators and neonatal equipment.
Complications of Surfactant Therapy
- Transient bradycardia and oxygen desaturation during administration.
- Pulmonary hemorrhage (in neonates with patent ductus arteriosus).
- Risk of infection or airway trauma.
Conclusion
Surfactant therapy remains a pivotal intervention in managing neonatal RDS. Advancements like MIST/LISA have improved outcomes and minimized risks. Neonatologists should tailor surfactant administration based on gestational age, clinical severity, and institutional protocols.