Paired maximum inspiratory and expiratory plain chest radiographs for assessment of airflow limitation in chronic obstructive pulmonary disease

Abstract

BackgroundThe usefulness of paired maximum inspiratory and expiratory (I/E) plain chest radiography (pCR) for diagnosis of chronic obstructive pulmonary disease (COPD) is still unclear. ObjectivesWe examined whether measurement of the I/E ratio using paired I/E pCR could be used for detection of airflow limitation in patients with COPD. MethodsEighty patients with COPD (GOLD stage I=23, stage II=32, stage III=15, stage IV=10) and 34 control subjects were enrolled. The I/E ratios of frontal and lateral lung areas, and lung distance between the apex and base on pCR views were analyzed quantitatively. Pulmonary function parameters were measured at the same time. ResultsThe I/E ratios for the frontal lung area (1.25±0.01), the lateral lung area (1.29±0.01), and the lung distance (1.18±0.01) were significantly (p<0.05) reduced in COPD patients compared with controls (1.31±0.02 and 1.38±0.02, and 1.22±0.01, respectively). The I/E ratios in frontal and lateral areas, and lung distance were significantly (p<0.05) reduced in severe (GOLD stage III) and very severe (GOLD stage IV) COPD as compared to control subjects, although the I/E ratios did not differ significantly between severe and very severe COPD. Moreover, the I/E ratios were significantly correlated with pulmonary function parameters. ConclusionsMeasurement of I/E ratios on paired I/E pCR is simple and reproducible, and can detect airflow limitation in patients with severe and very severe COPD.