Surfactant for RDS: When and how?

Abstract

This issue of The Journal contains two articles about surfactant therapy for respiratory distress syndrome (RDS). The big picture is that surfactant treatments for RDS are safe and very effective and are the standard of care. However, considerable controversy remains about when to treat infants at risk for or with RDS, how to give those treatments, and what sort of ventilatory support is best and for how long. Variables generating uncertainty are timing of treatment (at delivery/after initial stabilization), ventilatory support before and after treatment (continuous positive airway pressure [CPAP]/mechanical ventilation and type of mechanical ventilation), techniques for treatment (pharyngeal at delivery, number and volumes of boluses for each treatment, management after treatment). Each variable is further complicated by the gestational age/birth weight of each infant and the clinical status of the infant at birth. The Texas Neonatal Research Group performed a multicenter randomized trial to ask if larger infants (≥1250 g) with RDS and an oxygen requirement of ≥40% would benefit from immediate intubation and surfactant treatment compared with expectant management with surfactant treatment if the respiratory disease progressed. For this group of infants, an early intervention with surfactant treatment was of no benefit. This result supports the current clinical trend to use CPAP therapy for larger infants with RDS. Kaiser, Gauss, and Williams evaluated the effect of surfactant treatment on cerebral blood flow in very-low-birth-weight (VLBW) infants using continuous monitoring. They demonstrate that routine surfactant treatments result in a peak increase in Pco2 of about 20 mm Hg 15 minutes after the surfactant treatment. The increase in Pco2 is associated with an increase in cerebral blood flow velocity, demonstrating intact autoregulation of cerebral blood flow in these VLBW infants. The peak increase in Pco2 at 15 minutes probably results from airway occlusion with the surfactant suspension. The importance of the study is that it points out that surfactant therapy does cause transient physiologic changes that need to be balanced against benefit. For example, the decision to treat an infant on CPAP with surfactant requires intubation followed by surfactant instillation. Both procedures cause physiologic abnormalities that need to be recognized. Strategies for when to treat which patient and how remain hot topics in neonatology.