DETECTION OF EARLY LUNG IMPAIRMENT WITH AEROSOL BOLUS DISPERSION

The broadening of inhaled aerosol boluses (aerosol bolus dispersion) d uring respiration provides a noninvasive measure of convective gas mix ing in the lungs. In this study, the sensitivity and specificity of th is technique for the diagnosis of early lung impairment due to cigaret te smoking was evaluated. Two hundred and sixteen randomly selected su bjects (126 smokers and 90 nonsmokers) were investigated with aerosol dispersion in comparison to conventional lung function tests. The cumu lative cigarette consumption of the subjects was quantified by ''pack- years'' (PY). Smokers were classified into the following groups: 0< PY less than or equal to 10; 10< PY less than or equal to 20; 20< PY les s than or equal to 30; and PY >30. Forced expiratory volume in one sec ond (FEV(1)), maximal expiratory flow at 25, 50 and 75% vital capacity (MEF(25), MEF(50) and MEF(75) decreased significantly with increasing cigarette consumption. In comparison to nonsmokers, FEV(1) was signif icantly reduced in smokers of 10< PY less than or equal to 30, and MEF (75) was significantly reduced in smokers of PY >20. Aerosol bolus dis persion increased with increasing PY. For all groups of smokers, even those with PY <10, bolus dispersion was significantly increased in com parison to lifelong nonsmokers, indicating alterations in convective g as mixing in the lungs. Calculation of receiver operating characterist ics for the lung function parameters under consideration showed that b olus dispersion has a higher sensitivity and specificity than conventi onal lung function parameters. Hence, the aerosol bolus dispersion tes t could be a promising epidemiological tool to study early abnormaliti es in intrapulmonary gas mixing due to environmental factors.