In smokers without manifest airway obstruction, early emphysema and endothelial dysfunction has been related to minute-ventilation/carbon dioxide output ratio (V'E/V'CO2). Thus, smokers with reduced lung carbon monoxide diffusion capacity (DLco) have a heightened V'E/V'CO2 ratio. We hypothesized that ventilatory inefficiency could contribute to the suspicion of impaired diffusive capacity in the absence of significant airway obstruction. Thus, 15 smokers with impaired DLco were compared to 15 smokers with normal DLco. Accuracy through sensibility and specificity for V'E/V'CO2 slope and nadir was compared with a new index for ventilatory efficiency (ηV'E,%), to uncover early diffusive changes in smokers without COPD.
Keywords: Accuracy; Exercise; Lung diffusion capacity; Smokers; Ventilatory efficiency.
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