title: Ventilatory response to exercise in adolescents with cystic fibrosis and mild-to-moderate airway obstruction.
abstract: 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 (CO2) exhalation. Twenty-two adolescents with CF (12 boys and 10 girls; mean ± SD age: 14.3 ± 1.3 years; FEV1: 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 (VO2peak), breathing pattern, estimated ventilatory dead space ventilation (VD/VT ratio), minute ventilation (VE) to CO2 production relationship (VE/VCO2-slope), partial end-tidal CO2 tension (PETCO2), and the VE to the work rate (VE/WR) ratio were examined. VO2peak 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/VCO2-slope and PETCO2 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 CO2 exhalation (normal VE/VCO2-slope and PETCO2 values) during progressive exercise up to maximal exhaustion in CF patients with mild-to-moderate airway obstruction.
authors.affiliation: Department of Epidemiology, School for Public Health and Primary Care (CAPHRI), Maastricht University, Maastricht, The Netherlands ; Child Development & Exercise Center, Wilhelmina Children's Hospital, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Bart C
authors.initials: BC
authors.lastname: Bongers
authors.affiliation: Child Development & Exercise Center, Wilhelmina Children's Hospital, University Medical Center Utrecht, Utrecht, The Netherlands ; De Kinderkliniek, Almere, The Netherlands.
authors.forename: Maarten S
authors.initials: MS
authors.lastname: Werkman
authors.affiliation: Child Development & Exercise Center, Wilhelmina Children's Hospital, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Tim
authors.initials: T
authors.lastname: Takken
authors.affiliation: Child Development & Exercise Center, Wilhelmina Children's Hospital, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Erik H J
authors.initials: EH
authors.lastname: Hulzebos
keywords: Breathing pattern; Children; Pulmonary physiology; Ventilation