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. 2020 Jul 13;15:1697–1711. doi: 10.2147/COPD.S260735

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© 2020 Yamamoto et al.

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Inspiratory impedance at rest in the various GOLD stages (stages I–IV) (n=55). (A) Respiratory resistance and GOLD stages at baseline. (B) Respiratory reactance and GOLD stages at baseline. Sixteen subjects were GOLD stage I or II and 39 subjects were GOLD stage III or IV. **p<0.01 by the Mann–Whitney U-test.

Abbreviations: ALX, low-frequency reactance area; Fres, resonant frequency; GOLD, Global Initiative for Chronic Obstructive Lung Disease; R5 and R20, respiratory system resistance at 5 and 20 Hz, respectively; X5, respiratory system reactance at 5 Hz.