Introduction: Patients with chronic obstructive pulmonary disease (COPD) often present reduced exercise tolerance. Limitation of exercise capacity in COPD is an essential feature, which can be accurately determined by incremental cycle ergometry. The relationship between resting lung function variables and exercise capacity has been studied extensively in COPD patients. A clear relationship between resting pulmonary function testing and exercise capacity has not been established. The present study was designed to assess the accuracy of new index such as area under the maximal expiratory flow-volume curve [A(ex)] in predicting exercise capacity (expressed by maximum oxygen uptake - V'O(2max) and maximal mechanical work - W(max)) in COPD patients.
Material and methods: The study was performed on 41 patients with mild - to severe COPD (FEV1, 57.2 +/- 15.3% predicted). Each subject underwent resting spirometry (area under the maximal expiratory flow-volume curve - A(ex) was calculated). Subsequently, they performed maximal incremental cycle ergometer exercise for determination of V'O(2max), W(max).
Results: Significant correlation was found between A(ex) and V'O(2max) (r = 0.57, p < 0.001). In the group of severe COPD significant correlation was found between A(ex) and W(max) (r = 0.50 p < 0.05).
Conclusions: In chronic obstructive pulmonary disease, the index - area under the maximal expiratory flow-volume curve - A(ex), could be useful in assesment of COPD severity and in predicting exercise capacity.