Development of lung diffusion to adulthood following extremely preterm birth

Abstract

BackgroundGas exchange in extremely preterm (EP) infants must take place in foetal lungs. Childhood lung diffusing capacity for carbon monoxide (DLCO) is reduced; however, longitudinal development has not been investigated. We describe growth of DLCO and its sub-components to adulthood in EP-born compared to term-born subjects.MethodsTwo area-based cohorts born at gestational age ≤28 weeks or birth weight ≤1000 grams in 1982–1985 (n=48) and 1991–1992 (n=35) were examined twice, at ages 18 and 25, and 10 and 18 years, respectively, and compared to matched term-born controls. Single-breath DLCO was measured at two oxygen pressures, with sub-components [membrane diffusion (DM) and pulmonary capillary blood volume (VC)] calculated using the Roughton–Forster equation.ResultsAge-, sex- and height-standardized transfer coefficients for carbon monoxide (KCO), and DLCO were reduced in EP-born compared to term-born and remained so during puberty and early adulthood (p-values for all time points and both cohorts ≤0.04), whereas alveolar volume was similar. Development occurred in parallel to term-born controls, with no signs of pubertal catch-up growth nor decline at 25 years (p-values for lack of parallelism within cohorts 0.99, 0.65, 0.71, 0.94, and 0.44 for z-DLCO, z-VA, z-KCO, DM, and VC, respectively). Split by membrane and blood volume components, findings were less clear; however, membrane diffusion seemed most affected.ConclusionPulmonary diffusing capacity was reduced in EP-born compared to term-born, and development from childhood to adulthood tracked in parallel to term-born, with no signs of catch-up growth nor decline at age 25.