Tracheal diameter as a predictor of pulmonary function.

Abstract

Tracheal diameter (TD) was measured from standard posterior-anterior (PA) roentgenograms and evaluated as a predictor of pulmonary function. A population of 222 non-smokers with normal chest roentgenograms was analyzed. A subset of the population with the trachea indented two or more mm by the aorta (on PA film), as well as males and females, were analyzed separately. In males without aortic indentation of the trachea, tracheal diameter alone accounted for 28% of the variation in peak expiratory flow rate (PEFR). Age and height accounted for an additional 19% of the variation. Tracheal diameter was second to age as a predictor for forced expiratory volume in one second (FEV1) and forced vital capacity (FVC), accounting for an additional 10% of the variation in each. However, tracheal diameter did not explain significant variability in the female group. This study supports an upper airway effect on flow at large lung volumes. It also demonstrates that a tracheal diameter, measured from a PA chest film, is a useful predictor of pulmonary function that can be easily applied in population surveys.