P1.213: Trends in Early Dynamic Lung Compliance: A Predictor of Bronchopulmonary Dysplasia.

Background: Bronchopulmonary dysplasia (BPD) is a leading cause of significant respiratory morbidity in preterm infants, affecting approximately 12,000 to 15,000 newborns each year in the U.S. While prior research has explored objective measures of lung compliance for predicting BPD, key knowledge gaps remain. This study aims to evaluate whether early trends in dynamic lung compliance can serve as a reliable predictor of BPD severity at 36 weeks postmenstrual age (PMA).

Methods: Over 2.8 million data points were collected and analyzed from 99 infants in a level III NICU, with each point representing minute-by-minute lung mechanics during the first 72 hours of life. Dynamic lung compliance (Cdyn) data was extracted from conventional mechanical ventilators for each measurement and matched with other lung function indices, including set ventilator parameters and tidal volumes. Data were segmented into 12-hour intervals, and compliance trends were assessed by deriving individual linear slopes for each infant, where the y-intercept represented baseline compliance at birth. Both baseline compliance at birth and the rate of change in compliance were then correlated with BPD severity (classified per NICHD 2018 criteria). Due to non-normal distribution, nonparametric analyses were applied. Data were represented as median (IQR).

Results: The study included 99 infants with a median gestational age of 27 weeks and a median birth weight of 1069g. The cohort was 63% females and 37% males, with 44% African Americans, 53% Caucasians, and 3% categorized as other. Surfactant was administered to 93% of infants. By 36 weeks PMA, 52% had no BPD, 23% had mild BPD, and 21 % had moderate to severe BPD; 4% of infants died before 36 weeks.
No significant association was found between baseline compliance at birth and BPD severity (p=0.23). A strong linear relationship existed between compliance trends over 72 hours and BPD severity, with flatter or negative slopes associated with worse outcomes (p < 0.001). Infants with moderate to severe BPD exhibited a 42% (-78 to 10%) decline in compliance within the first 72 hours (p < 0.00001).

Conclusion: Early dynamic changes in lung compliance - rather than baseline values - may better predict BPD severity by 36 weeks. Monitoring compliance trends in the first 72 hours could help identify high-risk infants for moderate to severe BPD, enabling early targeted interventions.