Prolonged oxygen kinetics during early recovery from maximal exercise in adult patients with cystic fibrosis

Study objectives: To explore the significance of oxygen kinetics during ear ly recovery after maximal cardiopulmonary exercise testing (CPET) in the as sessment of functional capacity and severity of the disease in cystic fibro sis (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 ((V) over dot o(2)), carbon dioxi de production, and ventilation. Maximum (V) over dot o(2) ((V) over dot o(2 ) peak) and the first-degree slope of (V) over dot o(2) decline during earl y recovery ((V) over dot o(2)/t-slope) were calculated. To assess the sever ity of the disease, we used standard indexes like FEV1 (% predicted), (V) o ver dot o(2)peak, and a widely accepted system of clinical evaluation, the Schwachman score (SS), Results: (V) over dot o(2)/t-slope was significantly lower in CF patients c ompared to healthy subjects (0.61 +/- 0.31 L/min/min vs 1.1 +/- 0.13 L/min/ min; p< 0.01) and was closely cell-elated to FEV1 (r = 0.90, p < 0.001), (V ) over dot(2)peak (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 (V) over dot o(2)/t-slope. Conclusion: We conclude that in CF patients, the prolonged oxygen kinetics during early recovery from maximal exercise is related to the disease sever ity.