Elastic recoil of the lung in cigarette smokers: the effect of nebulized bronchodilator and cessation of smoking.

The mechanical properties of the lung, forced vital capacity, flow-volume relationships, lung volume, and single-breath N2 curve were determined in 16 nonsmokers and 19 smokers. Pulmonary elastic recoil, Pst (1), was significantly lower at all lung volumes, as were flow parameters, whereas lung volumes were higher in smokers of both sexes. The variables derived from forced vital capacity and single-breath N2 were significantly different from nonsmokers in male smokers but not in female smokers. The inhalation of nebulized bronchodilator was attended by a significant decrease in Pst (1) and in upstream flow resistance in smokers. After cessation of smoking Pst (1) decreased to values similar to those seen after bronchodilator administration, whereas resumption of smoking led to reversal of the pressure-volume curve. The data suggest that the elastic properties of the lungs are altered in cigarette smokers, but the extent of the disturbance is masked by constriction of the alveolar ducts or peripheral airways while smoking, and that these are unmasked by the administration of nebulized bronchodilator or by cessation of smoking.