Lung Ultrasound and Static Lung Compliance during Postnatal Adaptation in Healthy Term Infants

Abstract

Background: B-lines in lung ultrasound can be used to estimate lung liquid. B-lines are ring-down artifacts that arise from alterations to subpleural lung parenchyma. Lung ultrasound has been used to differentiate between diseases causing respiratory symptoms in neonates. B-lines are also seen in healthy infants during postnatal adaptation. Static lung compliance is a measure of the elasticity of the lungs. Objectives: Our aim was to document lung ultrasound findings, static lung compliance and their relationship during postnatal adaptation in healthy term infants. Methods: Lung ultrasound and measurement of static lung compliance were performed in 34 infants at ages of 0-4 and 24 h. B-lines in lung ultrasound were scored using a 5-step scale. Separate ultrasound scores for the upper and lower fields were also calculated. Results: A significant decrease in the abundance of B-lines and a concomitant significant improvement in static lung compliance was observed from <4 to 24 h of age. At <4 h the B-lines were significantly more abundant in the lower fields. No significant correlation existed between lung ultrasound and static lung compliance. Conclusion: The concomitant decrease in the B-lines in ultrasound and the increase in lung compliance during the first 24 h are likely to reflect clearance of lung liquid.