Table 4. Effects of different CPAP on airway resistance and work of breathing in COPD patients.
| CPAP (cmH2O) | Raw (cmH2O/L/s) | Pdi (cmH2O) | PTPdi (cmH2O·s) | ÄEELV (L) | PEEPi, dyn (cmH2O) |
|---|---|---|---|---|---|
| SB | 14.09±1.60 | 30.13±1.80 | 13.35±1.21 | 0.00±0.00 | 2.18±0.22 |
| 4 | 11.23±0.76* | 28.26±2.04 | 11.74±1.10 | –0.16±0.07* | 1.88±0.15* |
| 5 | 10.19±0.56*# | 28.61±2.32 | 10.69±1.17* | –0.17±0.11 | 1.63±0.17*# |
| 6 | 9.90±0.68* | 28.49±2.55 | 10.74±1.17* | –0.08±0.14 | 1.36±0.12*#† |
| 7 | 9.58±0.70* | 25.31±1.63*#†‡ | 9.87±1.16* | –0.08±0.15 | 1.57±0.11*#‡ |
| 8 | 10.45±0.84* | 26.13±1.99*† | 9.49±1.11*# | –0.16±0.20 | 1.30±0.11*#†§ |
| 9 | 10.21±0.68* | 27.30±2.04 | 10.22±1.06* | 0.26±0.12*#†‡§ | 1.37±0.13*#†§ |
| 10 | 11.52±0.73†‡§▲ | 25.19±2.19*#†‡ | 11.00±0.95*Ä▲ | 0.45±0.11*#†‡§Ä▲ | 1.79±0.13*‡§Ä▲ |
| F value | 5.995 | 3.854 | 4.905 | 4.858 | 12.961 |
| P value | 0.002 | 0.006 | 0.001 | 0.007 | <0.001 |
Data are presented as mean ± SE unless otherwise stated; P results of repeated analysis of variance (ANVOA) comparison between different CPAP levels; *P<0.05 vs. steady breathing; #P<0.05 vs. 4 cmH2O level; †P<0.05 vs. 5 cmH2O level; ‡ P<0.05 vs. 6 cmH2O; §P<0.05 vs. 7 cmH2O level; ÄP<0.05 vs. 8 cmH2O level; ▲P<0.05 vs. 9 cmH2O level. CPAP, continue positive airway pressure; Raw, airway resistance; Pdi, trans-diaphragmatic pressure; PTPdi, pressure-time product of diaphragmatic pressure; IC, Inspiratory capacity; ΔEELV, Changes in end expiratory lung volume; PEEPi, dyn, dynamic intrinsic positive end-expiratory pressure. SB, stable breathing.