Table 5.

Comparison of the change in respiratory resistance at 4 Hz, 20 Hz, and 35 Hz in inspiratory and expiratory phases between mild and moderate chronic obstructive pulmonary disease

	Mild	Moderate	P
Δ res R4	1.835 ± 0.916	2.238 ± 1.318	0.376
Δ ins R4	1.286 ± 0.525	1.451 ± 0.654	0.486
Δ ex R4	1.291 ± 0.716	1.347 ± 0.737	0.847
Δ res R20	0.844 ± 0.503	1.351 ± 1.126	0.151
Δ ins R20	0.680 ± 0.305	1.003 ± 0.543	0.074
Δ ex R20	0.535 ± 0.393	0.727 ± 0.634	0.364
Δ res R35	0.597 ± 0.308	1.007 ± 0.707	0.068
Δ ins R35	0.506 ± 0.192	0.855 ± 0.492	0.026*
Δ ex R35	0.356 ± 0.276	0.500 ± 0.525	0.392

Notes:

^*P < 0.05.

Comparisons between the two groups were performed using Student’s t-test.

Abbreviations: Δ ex, difference between the maximum and minimum respiratory resistance value in the expiratory phase; Δ ins, difference between the maximum and minimum respiratory resistance value in the inspiratory phase; Δ res, difference between the maximum and minimum respiratory resistance value in the respiratory phase; R4, respiratory resistance at 4 Hz; R20, respiratory resistance at 20 Hz; R35, respiratory resistance at 35 Hz.