Roentgenologic, physiologic and structural estimations of the total lung capacity in normal and emphysematous subjects

Abstract

The results of a previously described roentgenologic method for estimating total lung capacity are compared to those obtained using a conventional closed circuit helium method and the body plethysmograph method in twenty normal subjects and twenty patients with chronic pulmonary emphysema. In normal subjects, no significant difference was found in the total lung capacity among the three methods. In the emphysematous patients, the values for total lung capacity obtained by the roentgenographic and plethysmographic methods were the same but were significantly greater than those obtained by the helium dilution method and the predicted normal value. In sixty-six deceased subjects the total lung capacity, as determined with the roentgenographic method, correctly predicted the absence of emphysema in nineteen and showed a good correlation with the severity of anatomic emphysema in the remaining forty-seven. It is concluded that the roentgenologic method of estimating total lung capacity described by Barnhard et al. [19] is as accurate in normal and emphysematous subjects as the best physiological methods currently in use. Because it can be carried out simply, rapidly and inexpensively, it is recommended for office and hospital use and in large scale screening studies for pulmonary emphysema.