Table 3.
Results of Baseline Respiratory Impedance at Rest in the Various GOLD Stages (Stages I–IV) (n=55)
| Parameter | GOLD Stages I, II (n=16) | GOLD Stages III, IV (n=39) | p | ||
|---|---|---|---|---|---|
| R5, cmH2O/L/s | |||||
| Inspiratory | 2.70 (1.25) | 1.20–6.24 | 4.00 (1.14) | 1.96–6.96 | ** |
| Expiratory | 4.26 (2.88) | 1.53–13.83 | 5.14 (1.83) | 2.24–11.82 | * |
| Average | 3.48 (2.03) | 1.54–10.04 | 4.57 (1.36) | 2.10–9.14 | ** |
| ΔR5 | −1.56 (1.82) | −7.59–0.02 | −1.13 (1.36) | −5.64–1.19 | NS |
| R20, cmH2O/L/s | |||||
| Inspiratory | 2.18 (0.73) | 1.13–4.21 | 2.97 (0.71) | 1.71–4.75 | ** |
| Expiratory | 3.01 (1.54) | 1.44–7.94 | 3.45 (1.15) | 1.78–7.36 | NS |
| Average | 2.59 (1.10) | 1.49–6.08 | 3.21 (0.85) | 1.75–5.94 | ** |
| ΔR20 | −0.83 (0.97) | −0.37–0.18 | −0.48 (0.88) | −3.76–0.77 | NS |
| R5-R20, cmH2O/L/s | |||||
| Inspiratory | 0.52 (0.54) | −0.07–2.03 | 1.04 (0.56) | 0.25–2.80 | ** |
| Expiratory | 1.25 (1.38) | 0.01–5.89 | 1.69 (0.77) | 0.14–4.46 | ** |
| Average | 0.89 (0.94) | 0.01–3.96 | 1.04 (0.56) | 0.29–3.20 | ** |
| ΔR5-R20 | −0.73 (0.93) | −3.86–0.52 | −0.65 (0.62) | −2.53–0.42 | NS |
| X5, cmH2O/L/s | |||||
| Inspiratory | −0.69 (0.53) | −2.19 - −0.16 | −1.53 (0.84) | −3.55 - −0.19 | ** |
| Expiratory | −1.72 (2.85) | −11.11 - −0.08 | −4.43 (2.90) | −12.56 - −0.42 | ** |
| Average | −1.20 (1.67) | −6.65 - −0.13 | −2.98 (1.74) | −7.54 - −0.49 | ** |
| ΔX5 | 1.03 (2.39) | −0.15–8.92 | 2.90 (2.48) | −0.16–10.05 | ** |
| Fres, Hz | |||||
| Inspiratory | 9.87 (3.27) | 5.91–17.08 | 16.44 (5.55) | 6.58–30.60 | ** |
| Expiratory | 12.71 (6.37) | 5.56–28.20 | 23.10 (6.20) | 10.67–34.28 | ** |
| Average | 11.29 (4.71) | 5.74–22.64 | 19.77 (5.42) | 9.82–32.18 | ** |
| ΔFres | −2.84 (3.73) | −11.12–1.04 | −6.65 (4.58) | −18.51–0.37 | ** |
| ALX, cmH2O/L/s × Hz | |||||
| Inspiratory | 3.30 (3.43) | 0.54–13.25 | 11.79 (9.59) | 0.60–42.08 | ** |
| Expiratory | 13.41 (26.96) | 0.29–97.59 | 42.07 (32.70) | 2.04–145.30 | ** |
| Average | 8.35 (15.09) | 0.46–55.42 | 26.93 (19.58) | 1.93–83.41 | ** |
| ΔALX | −10.11 (23.80) | −84.34–0.81 | −30.28 (28.08) | −123.78–0.92 | ** |
Notes: Data are presented as the mean (SD) and the minimum and maximum values, unless otherwise stated. *and **p<0.05 and p<0.01 by the Mann–Whitney U-test, respectively.
Abbreviations: ALX, low-frequency reactance area; Δ, difference between inspiratory and expiratory phases; Fres, resonant frequency; GOLD, Global Initiative For Chronic Obstructive Lung Disease; NS, not significant; R5 and R20, respiratory system resistance at 5 and 20 Hz, respectively; SD, standard deviation; X5, respiratory system reactance at 5 Hz.