Lung function in school age children with chronic lung disease of prematurity

Background: Chronic lung disease of prematurity (CLDp) is attributed to a low gestational age of extreme prematurity (EP) and an immaturely developed respiratory system. We recently showed that school aged children born EP have similar lung function regardless of whether or not they developed Bronchopulmonary Dysplasia (BPD). We hypothesize that Forced Oscillation Technique (FOT) is superior to routine lung function tests in demonstrating sustained tissue damage and respiratory dysfunction in children with CLDp.
Methods: A non-selective prospective cohort study. 58 children born EP, 29 with/ 29 without BPD (BPD/non-BPD), versus 24 matched healthy controls at a mean age of 10.2±1.5 yrs. FOT and spirometry were performed before and after administration of β2 agonist (BD).

Results: No differences between BPD and non-BPD sub-groups were found in any spirometry or FOT indices measured at baseline or after BD. Compared to controls, CLDp children exhibited significantly lower FEV1, FEF50, mean respiratory reactance (Xavg), and higher resonance frequency (Fres) (p<0.01), but resistance and reactance at low frequencies (R6,X6) and frequency dependence of resistance were similar. Following BD, all spirometry and FOT indices improved, but differences in Xavg and Fres, and similarities in R6, X6, and spirometry indices remained.
Conclusions: Lung function abnormalities and changes in elastic properties of the respiratory system were observed in school-age children born EP, but neither spirometry nor FOT could distinguish between children with vs. without BPD. We suggest that CLDp may be mainly related to remodeling of lung parenchymal tissue and airway tone, and less to neonatal oxygen/ventilator dependency.