The aim of the study was to examine whether electrode belt of electrical impedance tomography (EIT) changed lung function in healthy volunteers, patients with respiratory muscle weakness (RMW) and chronic obstructive pulmonary disease (COPD).
In total 30 subjects were included (10 healthy volunteers, 10 subjects with RMW, maximum inspiratory pressure < 40 cmH2O, and 10 COPD, grade I - IV). Spirometry measurements were conducted in sitting position once a day at similar times on two consecutive days. Slow expiratory vital capacity (VC), forced vital capacity (FVC) and maximum voluntary ventilation (MVV) manoeuvres were performed. On day 1, spirometry was performed without the EIT electrode belt, and on day 2 the belt attached to the thorax.
Lung function was not influenced by the electrode belt in healthy subjects. Test-retest reliability in the healthy group was 0.89, 0.89 and 0.85 for VC, FVC and MVV, respectively. On the other hand, all investigated parameters were significantly decreased in the RMW group (VC, 51.3±18.0 vs. 46.5±18.0 %predicted, without vs. with EIT belt, p<0.01; FVC, 51.7±19.0 vs. 45.8±18.1 %predicted, p<0.01; MVV, 41.0±20.0 vs. 38.8±19.6 %predicted, p<0.01). VC and MVV also decreased significantly in the COPD group (VC, 77.4±20.5 vs. 74.6±18.8 %predicted, p<0.05; MVV, 57.4±15.7 vs. 54.4±12.5 %predicted, p<0.05).
EIT electrode belt could reduce lung volumes in subjects with pre-existing lung diseases. Comparing lung function acquired with electrode belt to corresponding values obtained without the belt should be avoided.

© 2020 Institute of Physics and Engineering in Medicine.