A Simplified, Regional Lung Ultrasound Score for Surfactant Administration in Neonatal RDS: A Prospective Observational Study

Abstract

Background: A total lung ultrasound score (tLUS) is a validated tool to describe parenchymal aeration, evaluate neonatal respiratory distress syndrome (RDS) progression and guide early surfactant replacement. tLUS derives from regional scores (rLUS) from predefined ultrasound views.

Research question: This paper explores the relative contribution of rLUS to tLUS and their predictive power of surfactant need for RDS, individually and with additional variables.

Study design and methods: This was a secondary analysis of multicenter, prospective, observational study. Preterm neonates with RDS were stabilized on nCPAP. Within 2 h of life, we calculated a tLUS (range 0-18) by summing 6 rLUS (using a 0-3 scale on midclavicular, anterior and posterior axillary line views) and the oxygen saturation/inspired oxygen fraction ratio (SatO₂/FiO₂). The administration of surfactant by a physician masked to the ultrasound results was used as reference test.

Results: We enrolled 175 preterm infants. A midclavicular (MC) score ≥ 2 was an early marker of aeration heterogeneity. Prognostic accuracy for surfactant need was high for the left MC score (AUC: 0.86 with sensitivity 0.79 and specificity 0.90) and the right MC score (AUC 0.87 with sensitivity 0.74 and specificity 0.93; optimal Youden cut-off = 2). A combined left + right MC score lead to an AUC: 0.90 (sensitivity 0.82. specificity 0.89; optimal Youden cut-off = 3). A prediction model including gestational age, SatO₂/FiO₂ and the combined MC score had an AUC 0.95.

Interpretation: rLUS are not always uniformly distributed in early RDS. The combined MC score is a simplified rapid and accurate predictor of surfactant replacement (alone or in combination with noninvasive variables) reducing stressful manipulations in first hours of life for preterm neonates.

Keywords: RDS; lung ultrasound score; neonate; surfactant.

FIGURE 1

Discriminative accuracy of LUS on left (a) and right (b) MC view for later surfactant administration.

FIGURE 2

(A) Comparison between the discriminative capacity of the sum of the MC left and right scores (regional score), red line, with respect to the total LUS, black line. (B) Comparison between the discriminative capacity of the multiple regression model with the regional score as predictor, (red Line) versus the multiple regression model with total LUS, (black line). Both Multiple regressions included gestational age and the SatO₂/FiO₂ ratio as covariate. [Color figure can be viewed at wileyonlinelibrary.com]