Pulmonary comorbidities and response to surfactant in late preterm infants: a multicenter cohort study

Surfactant (SRT) therapy is well-established for respiratory distress syndrome (RDS) in very preterm infants, but its effectiveness in late preterms (≥ 34 weeks' gestation) is less defined. We evaluated post-SRT oxygenation responses in late preterm infants in relation to pulmonary comorbidities.

In this multicenter prospective cohort, 350 late preterm infants received SRT according to European RDS guidelines. Pulmonary comorbidities-including persistent pulmonary hypertension (PPHN), meconium aspiration, air leaks, pulmonary hemorrhage, and pneumonia-were documented. Oxygen saturation to inspired oxygen ratios (S/F ratios) were recorded over 48 h. A good response was defined as a ≥ 50% increase in the S/F ratio or an S/F ≥ 428 (SpO₂ ≥90% in room air) at 6 h post-treatment.

Sixty-four percent of infants demonstrated a good response; 81% of these maintained sustained improvement. In a mixed-effects model evaluating factors influencing post-SRT improvement in oxygenation, PPHN (p < 0.001) and air leaks (p = 0.001) were significantly associated with less improvement. Meconium aspiration (p = 0.066) and pulmonary hemorrhage (p = 0.100) showed a negative trend, whereas congenital pneumonia showed no association. Responders received SRT earlier than nonresponders (median 7.2 vs. 15.6 h; p = 0.003).

Surfactant improves oxygenation in late preterm infants, though response depends on timing and comorbidities. Suboptimal response may indicate PPHN.

Surfactant therapy improves oxygenation in late preterm infants, but comorbidities such as PPHN and air leaks significantly reduce its effectiveness. Early administration is associated with a better response; treatment delays may contribute to poorer outcomes. Suboptimal response should prompt investigation for underlying conditions. Surfactant use should not be withheld solely based on gestational age.