Ventilatory efficiency during exercise: data from a contemporary cohort of preterm-born children

Abstract

Introduction: There are limited data describing ventilatory efficiency during exercise in preterm-born children. Aims: We hypothesised that preterm-born children who had chronic lung disease of prematurity (CLD) in infancy, have lower ventilatory efficiency (steeper minute volume [VE]/carbon dioxide uptake[VCO2] slope) during exercise than preterm- and term-born controls. Methods: From our on-going RHiNO (Respiratory Health Outcomes in Neonates) study, 7-12 years old children, born at ≤34 weeks’ gestation, with and without, a history of CLD, and term-born controls, underwent spirometry and exercise testing using cycle ergometry. Breath-by-breath measurements were averaged over 5-second intervals. The VE/VCO2 slope was estimated for each child (VE=a+b[VCO2]). The regression coefficients were then modelled with explanatory variables, using VE as the outcome. Results: Twenty-two children with a history of CLD, 28 preterm and 19 term controls completed the exercise protocol. The linear model was a good fit for the data (median R2= 0.98 range 0.75-0.99). The VE/VCO2 slope was noted to be higher in the CLD group (mean±SD 29.4±3.1) when compared to preterm (28.5±3.3) and term (27.5±6.0) controls, however, the groups were not statistically different (ANOVA p=0.3). Forced expiratory volume in 1 second (FEV1) and height were statistically significant (p= Conclusion: Reduced FEV1 in preterm-born children, rather than history of CLD, may be a more important in explaining differences in ventilatory efficiency during exercise when compared to term-born controls.