Exercise capacity and response of exercise-induced bronchoconstriction to bronchodilator in preterm-born children with low lung function

Introduction: Preterm-born children are at risk of long-term respiratory sequelae. We assessed whether diminished lung function in preterm-born children affects exercise capacity, and the response of exercise-induced bronchoconstriction (EIB) to bronchodilator therapy. Methods: From 79 children, mean age 11.6 years, recruited in our on-going RHiNO (Respiratory Health Outcomes in Neonates) study, 16 (PTlow) and 44 (PTC) preterm-born children of ≤34 weeks’ gestation were classified according to their predicted %FEV1 of ≤85% or >85% respectively; and 19 (TC) were term-born. Spirometry was performed at baseline, after maximal exercise and after post-exercise salbutamol. Results: Baseline spirometry was lower in the preterm groups compared to term controls (FEV1 78%, 98%, 104%; forced vital capacity, FVC, 89%, 102%, 105%; FEV1/FVC 0.77, 0.84, 0.87 for the PTlow, PTC and TC groups respectively). At maximum exercise, the PTlow group achieved lower load, and had lower minute ventilation, V̇O2 and V̇CO2 when compared to both control groups. All groups showed small, non-significant decreases in FEV1 after exercise. A significant response to bronchodilator was noted in all groups, although changes were similar between the groups (%FEV1 increases of 8%, 5%, 6%); however, greater proportion of children in the PTlow group improved their FEV1 by greater than 10% post-bronchodilator (44%, 16%, 16%). Conclusions: Preterm-born children with FEV1 deficits had lower exercise capacity but were at similar risk of EIB as both preterm and term controls, although a greater proportion of the EIB in the PTlow group responded to post-exercise bronchodilator.