Study objectives: To explore the significance of oxygen kinetics during early recovery after maximal cardiopulmonary exercise testing (CPET) in the assessment of functional capacity and severity of the disease in cystic fibrosis (CF) patients. Participants: Eighteen patients with CF (9 male/9 female; mean ± SD age, 23 ± 13 years) and 11 healthy subjects (3 male/8 female; mean age, 29 ± 4 years) underwent maximum CPET on a treadmill. Breath-by-breath analysis was used for measuring oxygen consumption (V̇O2), carbon dioxide production, and ventilation. Maximum V̇O2 (V̇O2peak) and the first-degree slope of V̇O2 decline during early recovery (V̇O2/t-slope) were calculated. To assess the severity of the disease, we used standard indexes like FEV1 (% predicted), V̇O2peak, and a widely accepted system of clinical evaluation, the Schwachman score (SS). Results: V̇O2/t-slope was significantly lower in CF patients compared to healthy subjects (0.61 ± 0.31 L/min/min vs 1.1 ± 0.13 L/min/min; p < 0.01) and was closely correlated to FEV1(r = 0.90, p < 0.001), V̇O2peak (r = 0.81, p < 0.001), and the SS (r = 0.81, p < 0.001). The multivariate analysis showed that the only independent predictor of the SS is the V̇O2/t-slope. Conclusion: We conclude that in CF patients, the prolonged oxygen kinetics during early recovery from maximal exercise is related to the disease severity.
- Cystic fibrosis
- Schwachman score