Effects of smoking on regional residual volume in young adults

Tests of overall lung function often reveal abnormalities in elderly smokers, but lung function is less consistently deranged in young smokers. Since airway closure at higher than normal lung volumes is thought to be an early indicator of lung dysfunction in asymptomatic smokers, we used 133xenon to measure regional residual volume, which is affected by airway patency, with the expectation that any abnormalities present in young smokers may be more apparent if searched for on a regional basis. We found no significant difference in overall lung function between 11 nonsmokers and 20 smokers (mean age=23.8 years), but residual volume was significantly higher in the lower-lung regions of the smokers. The results indicate that even in young persons the lungs are functionally disturbed by smoking, and the pattern of abnormality is similar to that seen in patients with chronic obstructive lung disease.