Table 2.
Comparison of forced oscillatory parameters
| Patients with COPD n = 74 | High EFL index group n = 37 | Low EFL index group n = 37 | Controls n = 39 | |
|---|---|---|---|---|
| R5 (cmH2O/L/s) Whole breath |
4.36 (1.58 – 8.06) |
5.09 (2.45 – 8.06)†* |
3.51 (1.58 – 7.99)* |
2.79 (1.15 – 5.70) |
| Inspiratory |
3.80 (1.57 – 8.16) |
4.80 (1.90 – 8.16)†* |
3.11 (1.57 – 7.64)* |
2.48 (1.01 – 5.03) |
| Expiratory |
4.78 (1.60 – 10.45) |
5.55 (2.86 – 10.45)†* |
4.17 (1.60 – 8.34)* |
3.04 (1.29 – 6.36) |
| ΔR5 |
-0.78 (-5.51 – 0.45) |
-0.98 (-5.51 – 0.45) |
-0.70 (-2.71 – 0.36) |
-0.54 (-2.39 – 0.16) |
| R20 (cmH2O/L/s) Whole breath |
3.21 (1.45 – 6.41) |
3.59 (1.77 – 6.00)†* |
2.86 (1.45 – 6.41)* |
2.57 (1.20 – 4.20) |
| Inspiratory |
3.03 (1.44 – 6.56) |
3.38 (1.79 – 5.27)†* |
2.56 (1.44 – 6.56)* |
2.47 (1.14 – 3.76) |
| Expiratory |
3.41 (1.52 – 7.66) |
3.72 (1.73 – 7.66)†* |
3.08 (1.52 – 6.26)* |
2.69 (1.26 – 4.84) |
| ΔR20 |
-0.29 (-3.31 – 0.34) |
-0.32 (-3.31 – 0.34) |
-0.28 (-1.72 – 0.30) |
-0.28 (-1.3 – 0.29) |
| R5-R20 (cmH2O/L/s) Whole breath |
1.22 (-0.04 – 2.96) |
1.51 (0.50 – 2.96)†* |
0.64 (-0.04 – 1.83)* |
0.25 (-0.76 – 1.76) |
| Inspiratory |
0.82 (-0.10 – 2.89) |
1.32 (0.11 – 2.89)†* |
0.39 (-0.10 – 1.99)* |
0.11 (-0.96 – 1.27) |
| Expiratory |
1.42 (0.02 – 3.52) |
1.99 (0.88 – 3.52)†* |
0.78 (0.02 – 2.08)* |
0.36 (-0.57 – 2.24) |
| Δ(R5-R20) |
-0.50 (-2.20 – 0.32) |
-0.68 (-2.20 – 0.30)†* |
-0.31 (-1.05 – 0.32) |
-0.29 (-1.15 – -0.04) |
| X5 (cmH2O/L/s) Whole breath |
-1.23 (-6.92 – 0.17) |
-2.77 (-6.92 – -0.48)†* |
-0.42 (-3.50 – 0.17)* |
-0.29 (-1.48 – 0.20) |
| Inspiratory |
-0.78 (-3.85 – 0.09) |
-1.57 (-3.85 – -0.11)†* |
-0.42 (-3.24 – 0.09)* |
-0.33 (-1.33 – 0.18) |
| Expiratory |
-1.63 (-11.17 – 0.25) |
-3.74 (-11.17 – -0.85)†* |
-0.37 (-3.77 – 0.25)* |
-0.23 (-1.64 – 0.21) |
| ΔX5 |
0.55 (-0.47 – 8.50) |
1.80 (0.59 – 8.50)†* |
-0.03 (-0.47 – 0.54) |
-0.06 (-0.37 – 0.48) |
| Fres (Hz) Whole breath |
13.74 (4.23 – 26.52) |
19.61 (7.91 – 26.52)†* |
7.97 (4.23 – 25.96)* |
6.53 (4.03 – 14.89) |
| Inspiratory |
10.87 (4.46 – 27.07) |
16.10 (5.76 – 24.83)†* |
8.16 (4.46 – 27.07)* |
6.71 (4.05 – 12.36) |
| Expiratory |
16.10 (4.00 – 28.20) |
22.27 (10.06 – 28.20)†* |
7.82 (4.00 – 24.85)* |
6.30 (4.00 – 17.42) |
| ΔFres |
-2.33 (-15.00 – 2.98) |
-6.34 (-15.00 – -0.08)†* |
0.14 (-5.74 – 2.98) |
0.17 (-5.37 – 1.75) |
| ALX (cmH2O/L/s x Hz) Whole breath |
7.44 (0.04 – 62.87) |
22.16 (1.96 – 62.87)†* |
1.42 (0.04 – 33.88)* |
0.92 (0.01 – 7.64) |
| Inspiratory |
3.54 (0.07 – 45.55) |
10.60 (0.37 – 45.55)†* |
1.48 (0.07 – 32.92)* |
1.02 (0.01 – 6.47) |
| Expiratory |
11.34 (0.00 – 106.35) |
32.20 (3.54 – 106.35)†* |
1.19 (0.00 – 34.83)* |
0.74 (0.00 – 8.87) |
| ΔALX | -3.31 (-86.95 – 2.35) | -15.51 (-86.95 – 0.00)†* | 0.05 (-5.73 – 2.35) | 0.15 (-3.96 – 1.11) |
Values are shown as a median (range).
Abbreviations: ALX integrated low-frequency reactance area, Δ difference between inspiratory and expiratory phases, EFL expiratory flow limitation, Fres resonant frequency, R5 and R20 respiratory system resistance at 5 Hz and 20 Hz, R5-R20 difference between R5 and R20, X5 respiratory system reactance at 5 Hz.
*p <0.05 versus controls, †p <0.05 versus low EFL index group.