Ventilatory response to exercise in adolescents with cystic fibrosis and mild-to-moderate airway obstruction

Data regarding the ventilatory response to exercise in adolescents with mild-to-moderate cystic fibrosis (CF) are equivocal. This study aimed to describe the ventilatory response during a progressive cardiopulmonary exercise test (CPET) up to maximal exertion, as well as to assess the adequacy of the ventilatory response for carbon dioxide (CO(2)) exhalation. Twenty-two adolescents with CF (12 boys and 10 girls; mean ± SD age: 14.3 ± 1.3 years; FEV(1): 78.6 ± 17.3% of predicted) performed a maximal CPET. For each patient, data of a sex- and age matched healthy control was included (12 boys and 10 girls; mean ± SD age: 14.3 ± 1.4 years). At different relative exercise intensities of 25%, 50%, 75%, and 100% of peak oxygen uptake (VO(2peak)), breathing pattern, estimated ventilatory dead space ventilation (VD/VT ratio), minute ventilation (VE) to CO(2) production relationship (VE/VCO(2)-slope), partial end-tidal CO(2) tension (P(ET)CO(2)), and the VE to the work rate (VE/WR) ratio were examined. VO(2peak) was significantly reduced in CF patients (P = 0.01). We found no differences in breathing pattern between both groups, except for a significantly higher VE at rest and a trend towards a lower VE at peak exercise in patients with CF. Significantly higher values were found for the estimated VD/VT ratio throughout the CPET in CF patients (P < 0.01). VE/VCO(2)-slope and P(ET)CO(2) values differed not between the two groups throughout the CPET. VE/WR ratio values were significantly higher in CF during the entire range of the CPET (P < 0.01). This study found an exaggerated ventilatory response (high VE/WR ratio values), which was adequate for CO(2) exhalation (normal VE/VCO(2)-slope and P(ET)CO(2) values) during progressive exercise up to maximal exhaustion in CF patients with mild-to-moderate airway obstruction.