Peri- and Neonatal Risk Factors and Structural Lung Abnormalities Predict Hypoxic Challenge Test Failure in Infants with Severe Bronchopulmonary Dysplasia

Introduction: Infants with severe bronchopulmonary dysplasia (BPD) are at increased risk of hypoxemia and often fail hypoxic challenge testing (HCT). The predictive value of clinical characteristics and structural lung abnormalities on HCT outcomes is unclear. Methods: This prospective cohort study included preterm-born infants (≤32 weeks gestation) with severe BPD enrolled in a standardized follow-up program. Perinatal and neonatal data were extracted from medical records. At 6 months corrected gestational age, structural lung abnormalities were quantified on chest CT using PRAGMA-BPD scoring. HCT was performed using a sealed body plethysmograph and failure was defined as inability to maintain oxygen saturation ≥ 85% for 20 minutes. Univariate and multivariable logistic regression analyses identified predictors of HCT failure. Results: Among 156 infants, 28.8% failed HCT. Of the perinatal and neonatal factors, patent ductus arteriosus (odds ratio 2.73, 95% confidence interval 1.29–6.14), pulmonary hypertension (2.57, 0.99–6.62), and longer duration of supplemental oxygen therapy (odds ratio per interquartile range increase (OR IQR ) 2.40, 1.55–3.71) were associated with failure. For structural lung abnormalities, higher composite PRAGMA-BPD scores (OR IQR 2.18, 1.36–3.48), higher hyper-attenuation (OR IQR 1.75, 1.17–2.63) and hypo-attenuation (OR IQR 1.45, 1.08–1.98) scores predicted failure. In multivariable analysis, only longer duration of supplemental oxygen therapy (OR IQR 2.04, 1.22–3.42) and higher composite PRAGMA-BPD scores (OR IQR 1.95, 1.15–3.31) remained independent predictors. Conclusion: Duration of supplemental oxygen therapy and structural lung abnormalities independently predict HCT failure, highlighting the clinical relevance of both structural and functional impairments in severe BPD.