We investigated the association between alveolarization levels and lung aeration assessed via ultrasound in a validated preterm rabbit model of experimental bronchopulmonary dysplasia (BPD). BPD is a multifactorial disorder characterized by disrupted alveolar and vascular development due to pre- and post-natal injuries. This condition progresses from early life to later infancy, often manifesting as chronic pulmonary insufficiency. Using the preterm rabbit model, which mimics human BPD through hyperoxia-induced impaired alveolarization, we sought to evaluate lung aeration through quantitative ultrasound. Lung ultrasound in infants with evolving BPD has shown promise in detecting early abnormalities, monitoring lung aeration loss, and guiding respiratory interventions. However, its correlation with alveolarization remains unexplored.
Preterm rabbits delivered at 28 days of gestation (equivalent to the human saccular lung development stage) were exposed to moderate (FiO2=0.7) or severe hyperoxia (FiO2=0.95), while control groups included preterm normoxic and healthy term rabbits. Lung ultrasound was performed on postnatal days 7 and 14, using a high-frequency micro-linear probe. Ultrasound findings in hyperoxic rabbits revealed heterogenous abnormalities, categorized into interstitial, interstitial-alveolar, or consolidated patterns. The radial alveolar count (RAC) was significantly lower in rabbits with more severe ultrasound patterns, with median values of 10.1, 7.8, and 7.3, respectively. A negative correlation between RAC and rabbit lung ultrasound score (rLUS) was observed, indicating that lung aeration measured by ultrasound correlates with alveolarization impairment. This study highlights the potential of lung ultrasound as a non-invasive tool for assessing lung aeration and underlying alveolarization in BPD, bridging gaps in monitoring and understanding disease progression.
