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Table 4 Lung motion velocity in tidal and forced inspiration and expiration phases among normal, chronic obstructive pulmonary disease (COPD) mild, and COPD severe groups

From: Vector-field dynamic x-ray (VF-DXR) using optical flow method in patients with chronic obstructive pulmonary disease

  Lung motion velocity, median [interquartile range] (mm/s) p values
(1) Normal (n = 47) (2) COPD mild (n = 14) (3) COPD severe (n = 22) Alla (1) vs (2) b (2) vs (3) c (1) vs (3) d
Right
 Tidal inspiration 16.8 [14.1, 19.9] 28.5 [21.7, 33.9] 25.1 [17.8, 31.3] < 0.001** < 0.001** 0.432 0.002**
 Tidal expiration -14.5 [-18.4, -11.5] -22.1 [-28.6, -19.2] -15.6 [-25.2, -12.9] < 0.001** < 0.001** 0.059 0.206
 Forced inspiration 28.8 [22.5, 36.2] 24.1 [20.7, 37.3] 36.3 [25.3, 47.6] 0.107 0.502 0.214 0.214
 Forced expiration -23.6 [-31.4, -18.5] -32.9 [-46.6, -20.8] -27.0 [-40.3, -21.9] 0.093 0.227 0.810 0.227
Left
 Tidal inspiration 20.8 [17.7, 23.4] 23.9 [22.3, 29.1] 24.6 [19.9, 26.2] 0.012* 0.018* 0.642 0.089
 Tidal expiration -19.3 [-21.5, -16.4] -25.5 [-30.9, -22.0] -18.4 [-23.8, -15.0] 0.009** 0.004** 0.038* 0.934
 Forced inspiration 31.2 [27.4, 36.5] 28.3 [23.5, 38.6] 31.6 [26.1, 39.0] 0.678 1.000 1.000 1.000
 Forced expiration -27.1 [-33.5, -22.0] -33.8 [-43.6, -27.7] -27.8 [-39.0, -21.1] 0.171 0.166 0.479 0.650
  1. Lung motion velocity downward is defined as positive direction. *p value ≤ 0.05. **p value ≤ 0.01. ap values are for the comparison of all groups by one-way analysis of variance on ranks. Post-hoc multiple comparison was analyzed with Holm-Bonferroni method. bp values are for the comparison between normal and COPD mild groups. cp values are for the comparison between COPD mild and severe groups. dp values are for the comparison between normal and COPD severe groups