Journal of applied physiology
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Multicenter Study
Reduced exercise ventilatory efficiency in adults with cystic fibrosis and normal to moderately impaired lung function.
Despite being a hallmark and an independent prognostic factor in several cardiopulmonary diseases, ventilatory efficiency-i.e., minute ventilation/carbon dioxide output relationship (V̇e/V̇co2)-has never been systematically explored in cystic fibrosis (CF). To provide a comprehensive frame of reference regarding measures of ventilatory efficiency in CF adults with normal to moderately impaired lung function and to confirm the hypothesis that V̇e/V̇co2 is a sensitive marker of early lung disease. CF patients were divided into three groups, according to their spirometry: normal (G1), mild impairment (G2), and moderate impairment (G3) in lung function. ⋯ The finding of impaired ventilatory efficiency in patients with normal lung function confirms the higher sensitivity of exercise testing in detecting early lung disease compared with spirometry. Dynamic hyperinflation plays a significant role in determining the behavior of V̇e/V̇co2 slope and intercept values with increasing lung function impairment. Apparently free from interference from mechanical constraints, V̇e/V̇co2 nadir seems the most reliable parameter to evaluate ventilatory efficiency in CF adults.