TABLE 2

Values of electrical impedance tomography (EIT) variables in the three study groups.

NonsmokersFormer smokersCurrent smokersp-value
Median t500.27 (0.21–0.33)0.33 (0.27–0.48)#0.35 (0.27–0.67)0.0003
Median t750.30 (0.25–0.38)0.48 (0.37–0.77)#0.86 (0.57–1.33)<0.0001
Median t900.82 (0.67–1.15)1.41 (1.03–2.21)#1.91 (1.33–3.53)¶+<0.0001
Median FEV1/FVCEIT0.97 (0.93–0.99)0.87 (0.78–0.96)#0.84 (0.69–0.92)<0.0001
CV FEV1/FVCEIT0.43 (0.38–0.48)0.47 (1.38–1.54)#0.58 (0.49–0.72)¶+<0.0001
CV t500.81 (0.70–1.01)1.10 (0.89–1.25)#1.08 (0.87–1.29)<0.0001
CV t750.58 (0.51–0.72)0.78 (0.66–0.92)#0.77 (0.64–0.97)<0.0001
CV t900.42 (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.