Early lung ultrasound at one hour of life and subsequent oxygen requirement during the first 48 h after birth: a...

Early identification of newborns at risk for respiratory support remains challenging. Lung ultrasound (LUS) provides real-time information on pulmonary aeration, while right diaphragmatic ultrasound evaluates respiratory muscle function.

To assess whether lung and right diaphragmatic ultrasound findings obtained at one hour of life differed between term and near-term newborns who subsequently required free-flow oxygen supplementation within the first 48 h after birth and those who did not.

This prospective observational study included term and near-term newborns undergoing standardized lung ultrasound and right diaphragmatic ultrasound at one hour of life. Lung ultrasound was performed using a six-region protocol with a 0-3 scoring system. Right diaphragmatic function was assessed by diaphragmatic thickening fraction and excursion. The primary outcome was the requirement for free-flow oxygen supplementation at any time during the first 48 h of life. Continuous variables are reported as median and interquartile range (IQR), and categorical variables as counts and percentages. Group comparisons, logistic regression, and receiver operating characteristic (ROC) curve analysis were performed.

A total of 121 newborns underwent ultrasound assessment at one hour of life. Free-flow oxygen supplementation within the first 48 h was required in 28 newborns (23.1%). Lung ultrasound score at one hour was significantly higher in newborns requiring oxygen than in those who did not (10.5 [IQR 9-11] vs. 7 [IQR 5-8], p < 0.001). Right diaphragmatic thickening fraction was 21.5% (IQR 17.2-24.1) in the oxygen group and 20.0% (IQR 18.2-22.7) in the no oxygen group, while right diaphragmatic excursion was 5.55 mm (IQR 5.25-5.8) and 5.6 mm (IQR 5.3-6.1), respectively; neither differed significantly between groups. In multivariable analysis adjusting for gestational age and cesarean delivery, lung ultrasound score remained significantly associated with subsequent oxygen requirement (adjusted OR 3.41 per one-point increase, 95% CI 2.08-5.60, p < 0.001). ROC analysis showed promising discriminatory performance in this exploratory cohort, with an AUC of 0.94 (95% CI 0.85-0.99); a lung ultrasound score threshold of 9 provided 89.3% sensitivity and 88.2% specificity.

In this cohort of term and near-term newborns, a higher lung ultrasound score at one hour of life was significantly associated with subsequent free-flow oxygen requirement within the first 48 h and showed promising discriminatory performance in this exploratory cohort. In contrast, right diaphragmatic ultrasound parameters did not clearly differentiate between groups. These findings support the potential role of early lung ultrasound in neonatal respiratory risk stratification, but external validation in larger prospective cohorts is required.