Lung function and pulmonary vascular resistance are not associated in 6-year-old children born extremely preterm

Aim Children born preterm are at increased risk of reduced lung function. The aim was to test whether lung function was associated with pulmonary vascular resistance. Methods Participants were recruited from a population-based cohort born in 2004-2007. Lung function was assessed with spirometry after administration of a beta2-agonist. Forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) were determined. Estimations of pulmonary vascular resistance, arterial dimensions, right ventricular wall thickness, sphericity, and systolic (TAPSE) and diastolic functions were performed with echocardiography. Adjusted regression analyses were used to study associations. Results Sixty-six children (33 boys) born at 22-26 weeks of gestational age (birthweights 460-1134 g) were assessed at a mean age of 6.7 years. Despite large variations in lung function with FVCz-scores ranging from -4.6 to +2.8, there were no associations between lung function and pulmonary arterial pressure, right ventricular structure or function. Children with higher FVCz-scores (r = .52, beta = .55 mm,P = .015) and higher FEV(1)z-scores (r = .58, beta = .73 mm,P = .001) exhibited larger pulmonary arteries. Conclusion In children born extremely preterm, lung function was not associated with pulmonary vascular resistance. Routine echocardiographic evaluation of extremely preterm children may not be indicated at age 6.5 years.