• Eleni Armeniakou, Georgia Perpati, Stavros Dimopoulos, Petros Roditis, Maria Avdikou, Nikolaos Barouchos, Vasiliki Dionisopoulou, and Serafim Nanas.
• 10th Pulmonary Department, Athens Chest Hospital, Athens, Greece.
• Respir Care. 2015 Aug 1; 60 (8): 116411711164-71.

BackgroundThe goal of this study was to explore the relation between oxygen kinetics during constant work load submaximal cardiopulmonary exercise test (CPET) and disease severity in adult subjects with cystic fibrosis.MethodsFourteen adult subjects with cystic fibrosis (CF; 8 males, 22 ± 4 y old) and a mean Schwachman score of 73 ± 11 and 10 healthy individuals (5 males, 29 ± 4 y old) underwent pulmonary function tests at rest, maximal and constant work load submaximal CPET on a cycloergometer. Breath-by-breath analysis was used for measuring oxygen kinetic parameters and the time constant (tau), expressing phase 2 of submaximal CPET.ResultsSubjects with CF had a significantly prolonged tau compared with healthy subjects (42.3 ± 21.5 vs. 29.3 ± 6.4, s, P < .05). The tau during phase 2 was inversely correlated with FEV1(% pred) (r = -0.77, P = .001), breathing reserve (r = -0.74, P = .003), V̇O2peak (r = -0.53, P = .049), V̇O2/t slope (r = -0.58, P = .03), and Schwachman score (r = -0.80, P = .001). In a multivariate regression model including all the above variables, the Schwachman score (β = -0.697, P = .002) emerged as independent predictor of tau (R2 = 0.719, P = .001).ConclusionsWe conclude that adult subjects with CF present significant prolonged oxygen kinetics during constant work load submaximal exercise in relation to disease severity. Thus, submaximal exercise should be considered the preferable CPET choice in adult patients with severe CF.Copyright © 2015 by Daedalus Enterprises.

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