Predicting the Need for Surfactant Based on Early Ultrasound Assessment of Lung Parenchymal Aeration in Preterm Infants with Respiratory Distress Syndrome on Non-Invasive Respiratory Support: A Prospective Cohort Study

Background. Modern clinical guidelines recommend surfactant administration when the oxygen requirement (FiO2) exceeds 0.3 during non-invasive respiratory support via continuous positive airway pressure (CPAP). However, this criterion is nonspecific and does not reflect the true extent of lung parenchymal involvement. Lung ultrasound enables a quantitative assessment of aeration decrease at the bedside without radiation exposure and prior to the onset of oxygen dependency.

The aim of the study was to evaluate the predictive characteristics of ultrasound assessment of lung parenchymal aeration in determining the need for surfactant administration in preterm infants with respiratory distress syndrome (RDS) on non-invasive respiratory support.

Methods. This prospective study included preterm infants with a gestational age (GA) of 26–34 weeks with RDS who received nasal CPAP (NCPAP) from birth with an FiO₂ ≤ 0.3. Lung parenchymal aeration was evaluated via ultrasound within the first 2 hours of life. Each scaned zone (anterior, lateral, and posterior on both sides) was assigned points from 0 to 3, where 0 — A-pattern (horizontal artifacts, normal aeration); 1 — B-pattern (fewer than 3 clearly defined B-lines); 2 — severe alveolar-interstitial syndrome (multiple confluent B-lines; possible subpleural consolidations); 3 — extensive lung parenchymal consolidation. Zone scores were summed up. The possible range for the total score was 0 to 18. The predicted outcome was surfactant administration within the first 3 hours of life.

Results. The study included 175 preterm infants; surfactant was administered to 95 (54%) of them. The median total lung ultrasound score was 10 (8; 12) in the group receiving surfactant and 4 (2; 6) in the group not receiving surfactant (p < 0.001). Differences in total scores between the groups were observed across all lung scanning zones (p < 0.001). The area under the ROC curve (AUC) for the total score was 0.911 (95% CI 0.865–0.951). At a threshold of ≥ 8 points, sensitivity was 82.1%, specificity was 96.2%, positive predictive value was 96.3%, and negative predictive value was 81.9%.

Conclusion. Ultrasound assessment of lung parenchymal aeration during the first 2 hours of life is an accurate, independent predictor of the need for initial surfactant administration in preterm infants with RDS on CPAP.

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