Spatial heterogeneity in regional pulmonary function in COPD patients and healthy young and elderly subjects

Introduction: Electrical impedance tomography (EIT) can determine regional dynamic gas volume changes in the lungs. The aim of our study was to examine the regional differences in lung function in COPD patients and healthy adults using EIT. Patients and methods: 33 COPD patients (GOLD II-IV) and 25 healthy young and elderly adults were studied. EIT data were collected at up to 44 images/s (Goe-MF II, CareFusion, Hoechberg, Germany) in parallel with spirometry. Regional inspiratory (IVC) and forced vital capacities (FVC), forced expired volume in 1s (FEV 1 ) and tidal volume (V T ) were determined in 912 EIT image pixels in the chest cross-section. Coefficient of variation (CV) was calculated from all pixel values to characterize the heterogeneity of lung function. The average value reflecting the volumetric changes in the cross-section was also determined. Statistical analysis was carried out by one-way ANOVA with Bonferroni post test. Results: The CV values of regional IVC, FVC, FEV 1 and V T were significantly different between healthy adults and COPD patients (p values: 0.0102, 0.0050, 0.0022 and 0.0047). No differences existed between the young and elderly subjects. The average IVC, FVC, FEV 1 and V T in the chest cross-section were significantly different among the groups (p values: 1 . Conclusion: EIT is able to detect disease and age related differences in regional lung function. The heterogeneity of lung function is similar in the young and elderly healthy subjects but lower than in COPD patients.