[Value of spirometric, pneumotachographic and oscilloresistometric studies in the functional diagnosis of obstructive respiratory tract diseases].

Tests were conducted on 90 smokers and a control group of 20 non-smokers using not only simple spirometry but also pneumotachography and the forced oscillation technique, including flow- and resistance-volume graphs. FEV1 was proved to be a sensitive screening test for early recognition of disfunction in the region of the small airways. 39,5% of the younger light smokers already showed signs of impairment to the breathing mechanics indicating exobronchial obstruction. The heavy, mostly older, smokers frequently showed complex disfunction, and in 55,3% the oscillatory resistance revealed quantifiable endobronchial obstruction. The oscillatory flow-resistance-increase-volume (as a percentage of vital capacity) proved the most sensitive small-airways-test during middle age, permitting significant distinction of smokers from non-smokers up to the age of 55.