Difference in diaphragmatic motion during tidal breathing in a standing position between COPD patients and normal subjects: Time-resolved quantitative evaluation using dynamic chest radiography with flat panel detector system (“dynamic X-ray phrenicogra

•Dynamic X-ray phrenicography is a useful method for the evaluation of the diaphragms.•Its radiation dose is comparable to conventional two projection chest radiography.•Diaphragm motion during tidal breathing is larger in COPD than in normal subjects.•Higher BMI is also associated with increased excursions of the bilateral diaphragm.

ObjectivesTo quantitatively compare diaphragmatic motion during tidal breathing in a standing position between chronic obstructive pulmonary disease (COPD) patients and normal subjects using dynamic chest radiography.Materials and methodsThirty-nine COPD patients (35 males; age, 71.3 ± 8.4 years) and 47 normal subjects (non-smoker healthy volunteers) (20 males; age, 54.8 ± 9.8 years) underwent sequential chest radiographs during tidal breathing using dynamic chest radiography with a flat panel detector system. We evaluated the excursions and peak motion speeds of the diaphragms. The results were analyzed using an unpaired t-test and a multiple linear regression model.ResultsThe excursions of the diaphragms in COPD patients were significantly larger than those in normal subjects (right, 14.7 ± 5.5 mm vs. 10.2 ± 3.7 mm, respectively, P < 0.001; left, 17.2 ± 4.9 mm vs. 14.9 ± 4.2 mm, respectively, P = 0.022). Peak motion speeds in inspiratory phase were significantly faster in COPD patients compared to normal subjects (right, 16.3 ± 5.0 mm/s vs. 11.8 ± 4.2 mm/s, respectively, P < 0.001; left, 18.9 ± 4.9 mm/s vs. 16.7 ± 4.0 mm/s, respectively, P = 0.022). The multivariate analysis demonstrated that having COPD and higher body mass index were independently associated with increased excursions of the bilateral diaphragm (all P < 0.05), after adjusting for other clinical variables.ConclusionsTime-resolved quantitative evaluation of the diaphragm using dynamic chest radiography demonstrated that the diaphragmatic motion during tidal breathing in a standing position is larger and faster in COPD patients than in normal subjects.