RESUMO
BACKGROUND: We evaluated the exercise capacity of children with cystic fibrosis to determine whether ventilatory limitation associated with static hyperinflation is related with decreased exercise capacity, thus predisposing these children to arterial hypoxemia during progressive exercise. METHODS: Thirty-seven children, ages 8-17 years, underwent spirometry, body plethysmography, and cardiopulmonary exercise testing after arterial catheter placement. According to the ratio of residual volume to total lung capacity (RV/TLC), the subjects were categorized as either with (RV/TLC > 30%) or without static hyperinflation (RV/TLC < 30%). RESULTS: Children with static hyperinflation showed lower values of maximum load per kilogram (% predicted) (P = .01), which was aggravated by ventilatory limitation (FEV(1) < 80% of predicted, peak oxygen consumption [% predicted] < 85%, and breathing reserve index > 0.7). Subjects with ventilatory limitation had significantly lower oxygen saturation (P = .04) and hypoxemia (P = .03) than did subjects without ventilatory limitation. CONCLUSIONS: In children with cystic fibrosis, static hyperinflation and ventilatory limitation are associated with decrease in exercise performance, oxygen saturation, and P(aO(2)) during maximum cardiopulmonary exercise testing. All children with cystic fibrosis who exhibit static hyperinflation and ventilatory limitation may require S(aO(2)) monitoring during progressive exercise.