Differential pulmonary residual volume determinations with radioactive xenon

A radioactive xenon inhalation procedure was used to determine differential residual volumes (right lung vs. left lung) in 28 normal subjects (6 of whom smoked approximately 1 package of cigarettes per day). The average right lung residual volume represented 54% of the total residual volume, whereas the average left lung residual volumerepresented 46% of the total. In addition, all of the subjects were studied by a standard helium dilution technique and found to have total lung residual comparable to the total lung residual volume as determined by the xenon technique. There was no statistical difference between the data obtained from cigarette smokers vs. nonsmokers. The noninvasive nature of the xenon technique makes this a useful procedure in determining differential residual volumes.