What does an L/S ratio of less than 2:1 typically warrant for preterm infants?

An L/S ratio, or lecithin/sphingomyelin ratio, is a crucial indicator of fetal lung maturity. A lower L/S ratio, specifically one that is less than 2:1, suggests that the surfactant levels in the infant's lungs are inadequate for proper alveolar function. Surfactant is a substance that helps reduce surface tension in the lungs, preventing the collapse of the alveoli and facilitating gas exchange after birth.

When the L/S ratio is below this threshold, it typically signifies a higher risk for respiratory distress syndrome (RDS) in preterm infants, a condition characterized by insufficient surfactant production. To address this, immediate surfactant therapy is warranted, as it can provide the necessary surfactant to improve lung function and oxygenation.

While other options may be relevant in different contexts of preterm care, they do not specifically address the immediate need for improving respiratory function, which is critical when dealing with an L/S ratio of less than 2:1. Therefore, administering surfactant therapy directly targets the underlying cause of potential respiratory issues in these infants.