A modified lung ultrasound score to evaluate short-term clinical outcomes of bronchopulmonary dysplasia

Abstract

Background: Lung ultrasound (LUS) is a useful tool for assessing the severity of lung disease, without radiation exposure. However, there is little data on the practicality of LUS in assessing the severity of bronchopulmonary dysplasia (BPD) and evaluating short-term clinical outcomes. We adapted a LUS score to evaluate BPD severity and assess the reliability of mLUS score correlated with short-term clinical outcomes.

Methods: Prospective diagnostic accuracy study was designed to enroll preterm infants with gestational age < 34 weeks. Lung ultrasonography was performed at 36 weeks postmenstrual age. The diagnostic and predictive values of new modified lung ultrasound (mLUS) scores based on eight standard sections were compared with classic lung ultrasound (cLUS) scores.

Results: A total of 128 infants were enrolled in this cohort, including 30 without BPD; 31 with mild BPD; 23 with moderate BPD and 44 with severe BPD. The mLUS score was significantly correlated with the short-term clinical outcomes, superior to cLUS score. The mLUS score well correlated with moderate and severe BPD (AUC = 0.813, 95% CI 0.739-0.888) and severe BPD (AUC = 0.801, 95% CI 0.728-0.875), which were superior to cLUS score. The ROC analysis of mLUS score to evaluate the other short-term outcomes also showed significant superiority to cLUS score. The optimal cutoff points for mLUS score were 14 for moderate and severe BPD and 16 for severe BPD.

Conclusions: The mLUS score correlates significantly with short-term clinical outcomes and well evaluates these outcomes in preterm infants.

Keywords: Bronchopulmonary dysplasia; Lung ultrasound; Premature.

Fig. 1

Description of the modified lung ultrasound score. Each lung has been divided into 4 areas. For each area, a 0- to 3- score was given, total score ranging from 0 to 24. Score values correspond to the different lung ultrasound semiology patterns, as shown in the middle and lower parts of the figure. RUA: right upper anterior; RLA: right lower anterior; RL: right lateral; RH: retrohepatic; LUA: left upper anterior; LLA: left lower anterior; LL: left lateral; RS: retrosplenic

Fig. 2

Correlation between mLUS score and NICHD/NHLBI BPD severity. The mLUS score is significantly correlated with NICHD/NHLBI BPD severity adjusted for gestational age (P < 0.001). Plot elements are represented as follows: mean (circle); median (horizontal line); interquartile range (gray box); and 95% confidence interval (whiskers). BPD: bronchopulmonary dysplasia; mLUS score: modified lung ultrasound score

Fig. 3

Correlation between mLUS score and short-term outcomes described as categorical variables. Panel A, B and C represent respiratory support at 40 weeks PMA, oxygen requirement at discharge and postnatal systemic steroids, respectively. The mLUS score is significantly correlated with respiratory support at 40 weeks PMA (P < 0.001), oxygen requirement at discharge (P = 0.03) and postnatal systemic steroids (P = 0.02) adjusted for gestational age. Plot elements are represented as follows: mean (circle); median (horizontal line); interquartile range (gray box); and 95% confidence interval (whiskers). Table shows Spearman correlation coefficients and results of multivariate linear regressions adjusted for gestational age. mLUS score: modified lung ultrasound score; r: Spearman correlation coefficient; β: adjusted linear regression coefficient

Fig. 4

Correlation between mLUS score and short-term outcomes described as continuous variables. Panel A, B and C represent duration of mechanical ventilation, duration of supplemental oxygen and length of hospital stay, respectively. The mLUS score is significantly correlated with duration of mechanical ventilation (P = 0.002), duration of supplemental oxygen (P < 0.001) and length of hospital stay (P < 0.001) adjusted for gestational age. Hatched blue curves represent the best fitting data lines and are all generated by local regression smoothing procedure. Table shows Spearman correlation coefficients and results of multivariate linear regressions adjusted for gestational age. mLUS score: modified lung ultrasound score; r: Spearman correlation coefficient; β: adjusted linear regression coefficient

Fig. 5

Receiver operating characteristic curves for assessing NICHD/NHLBI BPD severity using mLUS score and mLUS score. Two Panels respectively represent ROC curves for A moderate and severe BPD and B severe BPD. Different colors represent ROC curves for mLUS score (red) and cLUS score (green). Grey line represents the reference line. The areas under the curves for moderate and severe BPD shows significant difference between mLUS score and cLUS score. Table shows areas under the curves and 95% confidence interval. P-values for these comparisons are calculated. BPD: bronchopulmonary dysplasia; ROC curve: receiver operating characteristic curve; mLUS score: modified lung ultrasound score; cLUS score: classic lung ultrasound score