How does the degree of prematurity between 26 to 30 weeks gestation impact response to exogenous surfactant (pulmonary surfactant) therapy, such as poractant alfa (Curosurf) or beractant (Survanta), in preterm infants?

From the Guidelines

Infants born between 26 to 30 weeks gestation generally respond well to exogenous surfactant therapy, but the response varies based on gestational age, with earlier gestational age infants typically requiring more aggressive treatment than those closer to 30 weeks. The most recent and highest quality study, 1, published in 2014, supports the use of surfactant replacement therapy for preterm and term neonates with respiratory distress. According to this study, surfactant replacement, given as prophylaxis or rescue treatment, reduces the incidence of respiratory distress syndrome, air leaks, and mortality in preterm infants with surfactant deficiency.

Key Considerations

• Poractant alfa (Curosurf) is typically administered at an initial dose of 2.5 mL/kg (200 mg/kg), while beractant (Survanta) is given at 4 mL/kg (100 mg/kg) 1.
• Both can be repeated if necessary, with poractant often requiring fewer repeat doses.
• Extremely premature infants (26-27 weeks) frequently need multiple doses and have higher rates of treatment failure compared to more mature infants (29-30 weeks) 1.
• The difference in response to surfactant therapy occurs because lung development progresses significantly during these weeks - at 26 weeks, type II pneumocytes are just beginning to produce endogenous surfactant, while by 30 weeks, surfactant production is more established 1.
• Earlier gestational age infants have more immature alveolar structure, less developed pulmonary vasculature, and weaker respiratory muscles, all contributing to their increased vulnerability to respiratory distress syndrome and potentially diminished response to surfactant therapy.

Optimal Outcomes

• Surfactant should be administered early, ideally within the first two hours of life, using less invasive techniques when possible, and combined with appropriate respiratory support tailored to the infant's specific gestational age and clinical condition 1.
• Antenatal steroids and postnatal surfactant replacement independently and additively reduce mortality, the severity of respiratory distress syndrome, and air leaks in preterm infants 1.
• Continuous positive airway pressure, with or without exogenous surfactant, may reduce the need for additional surfactant and incidence of bronchopulmonary dysplasia without increased morbidity, although this has not been proven in large, randomized clinical trials 1.

From the FDA Drug Label

The FDA drug label does not answer the question.

From the Research

Surfactant Response in Preterm Infants

The degree of prematurity between 26 to 30 weeks gestation significantly impacts the response to exogenous surfactant therapy in preterm infants.

• Preterm infants with respiratory distress syndrome (RDS) benefit from exogenous surfactant therapy, which reduces the risk of pneumothorax and mortality 2.
• Natural surfactants, such as poractant alfa (Curosurf), have advantages over synthetic surfactants, including a lower frequency of pneumothorax and lower mortality 2, 3.
• Prophylactic administration of surfactant is preferred over "rescue" administration, especially in infants of < 30 weeks' gestation, as it decreases the risk of pneumothorax, pulmonary interstitial emphysema, and neonatal mortality 2.
• A regimen of using multiple doses of surfactant if required has advantages over a single dose regimen 2.
• Comparative trials with poractant alfa at a higher initial dose of 200 mg/kg appear to be associated with rapid weaning of FiO2, less need for additional doses, and decreased mortality in infants <32 weeks gestation when compared with beractant 3.

Impact of Gestational Age on Surfactant Response

• Infants born at 28-36 weeks of gestation who received minimally invasive surfactant therapy (MIST) had shorter hospitalization times and fewer side effects compared to those who received the INtubation, SURfactant administration, and Extubation (INSURE) technique 4.
• Antenatal dexamethasone administration may have an additive effect with exogenous surfactant therapy in reducing the incidence and severity of RDS, particularly in singleton pregnancies and infants between 28 and 32 weeks' gestation 5.

Surfactant Administration Methods

• MIST and INSURE are two methods of surfactant administration, with MIST being a less invasive technique that may reduce hospitalization time and side effects 4.
• Early rescue surfactant therapy (<30 min of age) is an effective method to minimize overtreatment of some preterm infants who may not develop RDS 3.
• Surfactant therapy followed by rapid extubation to nasal ventilation appears to be more beneficial than continued mechanical ventilation 3.