Respiratory function and symptoms in young preterm children in the contemporary era

Objective: To determine the relationships between respiratory symptoms, lung function, and neonatal events in young preterm children. Methods: Preterm children (<32 w gestation), classified as bronchopulmonary dysplasia (BPD) or non-BPD, and healthy term controls were studied. Lung function was measured by forced oscillation technique (respiratory resistance [Rrs] and reactance [Xrs]) and spirometry. Respiratory symptom questionnaires were administered. Results: One hundred and fifty children (74 BPD, 44 non-BPD, 32 controls) 4–8 years were studied. Lung function (median Z-score [10,90th centile]) was significantly impaired in preterm children compared to controls for FVC (0.00 [−1.18, 1.76], 0.69 [−0.17,1.86]), FEV₁ (−0.44 [−1.94, 1.11], 0.49 [−0.83, 2.51]), Xrs (−1.26 [−3.31, 0.11], −0.11 [−0.97, 0.73]), and Rrs (0.55 [−0.48, 1.82], 0.28 [−0.99, 0.96]). Only Xrs differed between the BPD and non-BPD (−1.51 [−3.59, −0.41], −0.89 [−2.64, 0.52]). The prevalence of recent respiratory symptoms (range: 32–36%) did not differ between BPD and non-BPD children. Supplemental O₂ in hospital was positively associated with worsening Xrs and FEV₁. Conclusion: Preterm children have worse lung function than healthy controls. Only respiratory reactance differentiated between preterm children with and without BPD and was influenced by days of O₂ in hospital. Pediatr Pulmonol. 2016;51:1347–1355.