Values of electrical impedance tomography (EIT) variables in the three study groups.
| Nonsmokers | Former smokers | Current smokers | p-value | |
| Median t50 | 0.27 (0.21–0.33) | 0.33 (0.27–0.48)# | 0.35 (0.27–0.67)¶ | 0.0003 |
| Median t75 | 0.30 (0.25–0.38) | 0.48 (0.37–0.77)# | 0.86 (0.57–1.33)¶ | <0.0001 |
| Median t90 | 0.82 (0.67–1.15) | 1.41 (1.03–2.21)# | 1.91 (1.33–3.53)¶+ | <0.0001 |
| Median FEV1/FVCEIT | 0.97 (0.93–0.99) | 0.87 (0.78–0.96)# | 0.84 (0.69–0.92)¶ | <0.0001 |
| CV FEV1/FVCEIT | 0.43 (0.38–0.48) | 0.47 (1.38–1.54)# | 0.58 (0.49–0.72)¶+ | <0.0001 |
| CV t50 | 0.81 (0.70–1.01) | 1.10 (0.89–1.25)# | 1.08 (0.87–1.29)¶ | <0.0001 |
| CV t75 | 0.58 (0.51–0.72) | 0.78 (0.66–0.92)# | 0.77 (0.64–0.97)¶ | <0.0001 |
| CV t90 | 0.42 (0.37–0.50) | 0.54 (0.43–0.63)# | 0.52 (0.42–0.62)¶ | <0.0001 |
Data are presented as median (interquartile range) unless otherwise stated. t50, t75 and t90: times needed to expire 50%, 75%, 90% of forced vital capacity; FEV1: forced expiratory volume in 1 s; FVC: forced vital capacity; CV: coefficient of variation. #: significant differences between former smokers and nonsmokers; ¶: significant differences between current smokers and nonsmokers; +: significant differences between current and former smokers.