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Lung function, maximum and submaximum exercise testing in COPD patients: Reproducibility over a long interval

par Noseda, André ;Carpiaux, Jean Pierre ;Prigogine, Thierry ;Schmerber, Jacqueline
Référence Lung, 167, 4, page (247-257)
Publication Publié, 1989

Article révisé par les pairs

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Résumé :

This study was designed to investigate the reproducibility and clinical relevance of several lung function and exercise test indices in a sample of patients with stable severe chronic obstructive pulmonary disease (COPD). Twenty subjects (ages 67.8 ± 2.0 years, forced expiratory volume in 1s, [FEV1] 39.7 ± 2.8% predicted) receiving conventional medical therapy and pulmonary rehabilitation were tested 4 times at 1 month intervals. Testing procedures included lung function (inspiratory vital capacity [IVC], FEV1, plethysmographic functional residual capacity [FRC], specific conductance of the airways (sGaw), single breath transfer factor divided by the alveolar volume [T(L)/VA]); incremental, progressive, symptom-limited, cycle exercise (maximum work load [Ẇ(max)], maximum heart rate [HR(max)], maximum ventilation [V̇(E)max], maximum oxygen uptake [V̇(O2)max]); and 2 modes of submaximum exercise (12 min walking test [12 MWD] and endurance cycle test). The mean of the absolute value of the individual patient, session-to-session, variation was found to be 0.131 for FEV1, 102 ml/min for V̇(O2)max. The within-subject variability was the smallest for HR(max) and IVC (mean intrasubject coefficient of variation, [C̄V̄ intra] 5.0 and 6.5%) and the greatest for T(L)/VA, the work performing during the endurance cycle test (EW) and sGaw (C̄V̄ intra 16.5, 19.4, and 22.7%), while it was reasonably low (8.1-10.2%) for all the other variables studied. Calculation of the F ratio of the intersubject variance to the residual (total minus intersubject) variance, inperpreted as a signal-to-noise ratio, yielded the following, in decreasing order: T(L)/VA, EW, V̇(E)max, V̇(O2)max, IVC, FEV1, HR(max), Ẇ(max), sGaw, 12 MWD, FRC. If we assume that a useful variable should combine a low within-subject variability (C̄V̄ intra ≤ 10%) with a high signal-to-noise ratio, we conclude that, among all the variables studied, IVC, FEV1, V̇(E)max, and V̇(O2)max are those with the greatest clinical potential for functional assessment in patients with COPD.