Long-Term pulmonary function outcomes in survivors of congenital diaphragmatic hernia

Congenital diaphragmatic hernia (CDH) is a rare developmental defect associated with pulmonary hypoplasia and long-term respiratory morbidity. Data on pulmonary function trajectories and structural predictors in CDH survivors remain limited. Objective of this study was to quantify long-term pulmonary dysfunction and its predictors in survivors of congenital diaphragmatic hernia (CDH). A prospective single-centre cohort of CDH survivors who underwent pulmonary function testing (PFT) between 2013 and 2023 was analysed. A total of 338 PFTs from 260 patients (57.7% male; birth years 2000–2017) were included; body plethysmography was available in 156 cases. Thoracic morphology was assessed by computed tomography or magnetic resonance imaging performed within six months of PFT. Spirometric and plethysmographic parameters were evaluated using z-scores derived from Global Lung Function Initiative reference equations. Associations with clinical characteristics, neonatal course, surgical technique, and imaging-derived thoracic indices were analysed using non-parametric testing, correlation analysis, and multiple linear regression. Obstructive ventilatory impairment occurred in 24.6% (mild 20.6%, moderate 44.4%, severe 22.2%); restrictive ventilatory impairment in 22.4% (mild 51.4%, moderate 40.0%, severe 8.6%). Lower zFEV₁ was associated with prenatal diagnosis, right-sided hernia, large defect, liver herniation, extracorporeal membrane oxygenation (ECMO), open repair and patch closure (all p ≤ 0.003). Regression (R² = 0.32) showed + 0.51 zFEV₁ per kg birth weight; negative coefficients for large defect (-0.39), right-sided hernia (-0.57), ECMO (-0.64) and open repair (-0.97). Haller index > 2.7, correction index ≥ 0.1 or asymmetry index outside 0.95–1.05 further reduced zFEV₁ and/or zTLC (p ≤ 0.03). During 3–5-year follow-up (n = 50), lung function stabilised or improved in 82%, but progressive obstruction developed in 18%. Approximately one quarter of CDH survivors exhibit persistent ventilatory deficits; defect severity, intensive therapy and chest-wall deformity independently predict poorer outcomes. The high incidence of long-term pulmonary impairment in CDH survivors supports the need for standardized long-term surveillance, particularly in children who already show pulmonary function impairment or other clinical signs consistent with respiratory limitation.