Table 4.
Comparison of IOS parameters between the healthy control and COPD groups
| Healthy controls | COPD | COPD 1 | COPD 2 | COPD 3 | COPD 4 | |
|---|---|---|---|---|---|---|
| Z5 (%predicted) | 89.24±29.98 | 159.50 (111.30 to 225)a | 114.32±54.47 | 150.22±78.02a | 195.57±80.87a,b | 266.3±138.33a–c |
| Fres (L/s) | 12.62±3.84 | 23.23±7.60a | 16.9±6.52 | 21.48±5.71a | 25.46±6.11a,b | 27.71±9.32a–c |
| X5 (kPa/L/s) | −0.09±0.05 | −0.25 (−0.41 to −0.14)a | −0.17±0.12 | −0.23±0.18a | −0.33±0.2a,b | −0.49±0.26a–c |
| R5 (%predicted) | 86.56±28.39 | 140.50 (106.55 to 185.7)a | 105.25±44.79 | 134.52±61.75a | 165.54±64.12a,b | 214.64±109.68a–c |
| R20 (%predicted) | 82±24.65 | 97.92±33.42a | 84.48±25.25 | 96.55±31.44a | 100.26±38.42a,b | 106.61±32.9a,b |
| R5–R20 (%predicted) | 115.96±103.54 | 458.23 (241.95 to 663.40)a | 248.8±258.35 | 382.9±312.48a | 606.22±295.68a,b | 920.03±664.1a–c |
Notes: Data are expressed as mean ± standard deviation and median (IQR).
a
P<0.05 compared with the healthy controls.
b
P<0.05 compared with COPD 1.
c
P<0.05 compared with COPD 2.
Abbreviations: IOS, impulse oscillometry; Z5, respiratory impedance; Fres, resonant frequency; X5, respiratory reactance; R5–R20, respiratory resistance; IQR, inter-quartile range.