Regional lung function in nonsmokers and asymptomatic current and former smokers

Barbara Vogt; Kathinka Deuß; Victoria Hennig; Zhanqi Zhao; Ingmar Lautenschläger; Norbert Weiler; Inéz Frerichs

doi:10.1183/23120541.00240-2018

Regional lung function in nonsmokers and asymptomatic current and former smokers

ERJ Open Res. 2019 Jul 15;5(3):00240-2018. doi: 10.1183/23120541.00240-2018. eCollection 2019 Jul.

Authors

Barbara Vogt¹, Kathinka Deuß¹, Victoria Hennig¹, Zhanqi Zhao^{2

3}, Ingmar Lautenschläger¹, Norbert Weiler¹, Inéz Frerichs¹

Affiliations

¹ Dept of Anesthesiology and Intensive Care Medicine, University Medical Center Schleswig-Holstein, Campus Kiel, Kiel, Germany.
² Dept of Biomedical Engineering, Fourth Military Medical University, Xi'an, China.
³ Dept of Biomedical Engineering, Furtwangen University, Villingen-Schwenningen, Germany.

Abstract

Electrical impedance tomography (EIT) is able to detect rapid lung volume changes during breathing. The aim of our observational study was to characterise the heterogeneity of regional ventilation distribution in lung-healthy adults by EIT and to detect the possible impact of tobacco consumption. A total of 219 nonsmokers, asymptomatic ex-smokers and current smokers were examined during forced full expiration using EIT. Forced expiratory volume in 1 s (FEV₁), forced vital capacity (FVC) and FEV₁/FVC were determined in 836 EIT image pixels for the analysis of spatial and temporal ventilation distribution. Coefficients of variation (CVs) of these pixel values were calculated. Histograms and medians of FEV₁/FVC_EIT and times required to exhale 50%, 75%, 90% of FVC_EIT (t₅₀, t₇₅ and t₉₀) were generated. CV of FEV₁/FVC_EIT distinguished among all groups (mean±sd: nonsmokers 0.43±0.05, ex-smokers 0.52±0.09, smokers 0.62±0.16). Histograms of FEV₁/FVC_EIT differentiated between nonsmokers and the other groups (p<0.0001). Medians of t₅₀, t₇₅ and t₉₀ showed the lowest values in nonsmokers. Median t₉₀ separated all groups (median (interquartile range): nonsmokers 0.82 (0.67-1.15), ex-smokers 1.41 (1.03-2.21), smokers 1.91 (1.33-3.53)). EIT detects regional ventilation heterogeneity during forced expiration in healthy nonsmokers and its increase in asymptomatic former and current smokers. Therefore, EIT-derived reference values should only be collected from nonsmoking lung-healthy adults.