Relationship between simplified and extended lung ultrasound aeration scores and oxygenation metrics in very preterm infants in the first month of life: a prospective observational study.

UNLABELLED: We evaluated the correlation between the simplified and extended lung ultrasound (LUS) aeration scores with oxygenation in very preterm neonates during the first month of life, focusing on how the relationship varies over time and with gestational age (GA). This prospective observational study included neonates born before 32 weeks' GA. LUS was performed on postnatal days 2, 7, 14, and 28. The simplified score assessed six anterolateral fields; the extended score added four posterior fields. Each field was graded on a 4-point scale. We used Spearman's coefficients to assess LUS-OSI correlations and Steiger's Z-test to compare them. We also built multivariable models for OSI, including GA, LUS, and their interaction as predictors. We enrolled 61 infants with a median (Q1, Q3) gestational age of 29.1 (27.1, 31.1) weeks. The extended score correlated more strongly with OSI than the simplified score (ρ = 0.69 vs 0.58, p < 0.001). Including posterior lung fields added limited value in the first two postnatal days but significantly improved OSI correlation thereafter. Both scores significantly enhanced GA in explaining OSI on days 2 and 28. We also observed a negative interaction between GA and LUS in explaining OSI.

CONCLUSION: During the first two postnatal days, the simplified LUS aeration score effectively reflects respiratory support needs, providing information beyond GA. Afterwards, including posterior lung fields significantly improves the correlation between LUS and OSI, with the largest difference between simplified and extended scores observed at 2 weeks, especially in more mature infants.

WHAT IS KNOWN: • Quantitative lung ultrasound (LUS) aeration score is a validated tool for grading the severity of neonatal lung disease, with multiple clinical applications. • A simplified LUS score (assessing 6 anterolateral areas) is sufficient during the first 24 hours of life; while an extended LUS score (adding 4 posterior areas) is recommended afterwards.

WHAT IS NEW: • During the first 48 hours postnatally, the simplified LUS score reliably reflects the need for respiratory support, offering information beyond gestational age alone. • Including posterior lung fields in the assessment markedly enhances the correlation between LUS scores and oxygenation metrics, especially at 2 weeks of age and in infants of higher gestational age.