Small airway disease: comparison of tests in young smokers versus nonsmokers.

A number of new tests for detection of small airway disease have been developed in the past several years. It is hoped that these will prove valuable as screening tests to detect those at risk of developing obstructive airway disease. We obtained data on the degree of discrimination of single breath nitrogen studies (CV/VC, CC/TLC, deltaN2/L), air-He studies (Vmax50), and the maximal midexpiratory flow (FEF25-75%) in detecting abnormalities in young smokers. Only the CV/VC and CC/TLC significantly separated smokers from nonsmokers, each revealing 20% abnormal values in smokers.