Fractional exhaled nitric oxide concentration in school-aged children born who had chronic lung disease in infancy

Introduction: Preterm-born children with chronic lung disease of prematurity (CLD) have lower FEV1 than preterm-born children without CLD and term-born controls. However, the underlying reasons for ongoing lung spirometry deficits are unclear. Fractional exhaled nitric oxide (FENO) is associated with lung conditions with airway inflammation but the role of FENO in CLD remains unclear.

Aims: We, therefore, compared FENO levels in children who had CLD in infancy comparing the results with preterm controls who did not have CLD in infancy and term controls.

Methods: From 241 children with mean age 10.6 years recruited in our on-going RHiNO (Respiratory Health Outcomes in Neonates) study, 180 children were born at ≤34 weeks’ gestation, 55 had CLD in infancy and 125 did not; and 61 were term-born. Spirometry was performed and FENO measured by NIOX Vero (Circassia, Oxford, UK).

Results: As expected preterm-born children with CLD had lower spirometry compared to preterm and term controls (%FEV1: CLD 84.2%, Preterm 92.1% and term 93.8% respectively). FENO levels were similar between all three groups (CLD 19.3, preterm 17.4, term 18.7 ppm respectively). Furthermore, using established cut-off values of 35 ppm to signify airway inflammation did not reveal any differences between the groups (CLD 16%, Preterm 8%, Term 13%). There was no evidence of a relationship between CLD diagnosis or spirometry with FENO.

Discussion: As expected spirometry was lower in the CLD group but FENO was not increased suggesting that eosinophilic inflammation is unlikely to play a part in the on-going spirometry deficits in preterm-born children who had CLD in infancy.