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.
Development of lung diffusion to adulthood following extremely preterm birth
