Fig. 2

EIT images examples. C: The patient from the COPD group Global inhomogeneity (GI) of electrical impedance tomography derived regional pulmonary function measures of forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC), FEV1/FVC, forced inspiration vital capacity (FIVC), middle expiratory flow rate at 25% to 75% of FVC (MEF25-75), time required to exhale 75% of FVC (T-75) in COPD, PRISm, Normal patients; FEV1/FVC abnormal aera: pixels with an fEIT FEV1/FVC ratio less than 0.7 of the total lung region pixels; CoV: center of ventilation; Averaged time required: the time required to exhale 75% of FVC; Time constant: as numerical statistics, the median (τmed) and interquartile range (τiqr) of regional time constants