Regional lung function in asymptomatic cigarette smokers.

Regional pulmonary ventilation and perfusion were studied in the supine posture using xenon-133 in 10 asymptomatic cigarette smokers with normal chest radiographs and no evidence of large airway obstruction. The results were compared with those obtained in age-matched control subjects who were lifelong nonsmokers. The ventilation of the upper zones of the lungs was significantly less than that of the lower zones in smokers but not in control subjects, and perfusion of the upper zones of the lungs was significantly greater than that of the mid-zones in control subjects but not in smokers. It is suggested that the upper zone abnormalities found in the group of smokers were consistent with the development of early emphysema.