Buist et al, studying a large number of subjects who attended an emphysema screening center, reported that CV is more sensitive than maximum expiratory flow rates for the detection of obstructive disease in its early stages. However, it should be noted that they refer only to a selected group of the cigarette-smoking population. On the other hand, Fulmer et al correlated functional with pathologic findings in patients with idiopathic fibrosis. They found that the most sensitive predictor of small airways narrowing is an abnormal dynamic compliance and that only flow-volume curves are in good correlation with this parameter.
In addition, they noted that CV is not useful for the detection of small airways abnormalities, because of its high variability, while the RV/TLC is even less sensitive in patients with idiopathic fibrosis. McFadden et al, studying the relative yields of the various tests for the detection of SAD, have also reported a higher incidence of abnormality in maximum expiratory flow rates than in CV or RV Deo reduction, which also included between the studied indices, is accepted by some authors as the earliest abnormality of the pulmonary involvement in scleroderma.