Development of lung function in “healthy” preterm infants during the first six years of life

Abstract

Background: Even in the absence of any respiratory disease during neonatal period, reduced lung function (LF) has been reported in preterm (PT) infants. We have previously found that the differences observed between term (T) controls and “healthy” PT infants at 6 months in Crs, V'maxFRC, FEV0.5 and FEF25-75% were no longer evident at 18 months (de Mir I. et al, ERS 2015).

Aims: Assessing LF at 4, 5 and 6 years in children born PT without neonatal respiratory disease and compare to those obtained in healthy children born full-term.

Methods: LF was measured in 'healthy' preterm (30-35.8 weeks) and full-term Spanish white children at 4, 5 and 6 years of age. Measurements of sReff and sRot during tidal breathing with a plethysmographic body box, a forced spirometry and a bronchodilator test were performed. sRaw and spirometry z-scores were calculated from the Asthma UK initiative (Kirby J. Eur Respir J 2010) and GLI equations (Quanjer, Eur Respir J 2012).

Results: 109 children were studied. 87 children (44 T/43 PT) were followed up at 4 years, 61 (33 T/28 PT) at 5 and 105 (55 T/50 PT) at 6 years of age. No differences were found between sexes. FVC, FEV0.5, FEV0.75, FEV1, FEV1/FVC, FEV0.75/FVC, MEF75, MMEF, sReff and sRot were collected. Compared to T controls, children born preterm had significantly lower FEV0.75 at 6 years [z- score mean (SD) -0.26 (1.32) vs 0.19 (0.98)]. No differences were found in the rest of LF parameters studied between both groups.

Conclusions: The differences observed between T controls and “healthy” PT infants at 6 months were no longer evident at 4, 5 and 6 years except from z-score FEV0.75, suggesting a catch-up of LF in this group of children born preterm.