Respiratory distress syndrome (RDS) is a condition among premature infants characterized by insufficient pulmonary surfactant and structural immaturity of the lungs. Surfactant decreases the surface tension of the water in the alveoli which allows the lungs to expand easier and more evenly. Without it, the alveoli become damaged and oxygenation is diminished. RDS is a leading cause of death among preterm infants.
Mechanism of Action
Surfactant is produced in the lungs to enable them to expand normally. It reduces the surface tension of the alveoli to prevent collapse. A preterm infant is often born with less than 10% the surfactant of a term neonate which makes breathing difficult, diminishes oxygenation, and can lead to further lung damage.
Surfactant can be administered to make up for the neonate's lack of surfactant at birth. These materials are often synthetic, animal derived compounds of lipids and proteins to mimic human surfactant. Administration of surfactant into the lungs is costly and requires skill and often artificial ventilation.
Current Use in High-Resource Settings
Surfactant is administered either as a prophylaxis or as a rescue measure in response to RDS. It is generally administered by specialists in neonatal intensive care units or equivalent hospital departments. Current surfactants are administered as an injection by an endotracheal tube. This bolus then spreads to the distal airways as the lungs move. Most infants are mechanically ventilated after each surfactant dose, and extubated only when stable on minimal ventilation. Surfactant can be re-administered as necessary, every 6-12 hours.
Application in Low-Resource Settings
The high cost of both surfactant and its accompanying technologies mean that surfactants are used almost exclusively in well-equipped neonatal intensive care units. Recent data suggests that in very preterm infants (24-27 weeks gestation) CPAP may reduce the need for surfactant.
Related Technologies in Development
Seattle Children's Surfactant, Surfactant Replacement from the University of Florida