Table 2.
Changes in cardiopulmonary variables after pulmonary rehabilitation in the peak V’O2 increase and peak V’O2 non-increase groups (n = 38).
| Peak V’O2 Inc. Group (n = 14) |
Peak V’O2 Non-Inc. Group (n = 24) |
p-Value (Between the Two Groups) | |||
|---|---|---|---|---|---|
| Pre-PR | Difference | Pre-PR | Difference | ||
| Pulmonary function | |||||
| FEV1, L | 0.77 (0.26) | +0.16 (0.19) * | 0.87 (0.30) | +0.02 (0.13) | 0.0514 |
| IC, L | 1.58 (0.42) | +0.16 (0.34) | 1.78 (0.47) | −0.10 (0.33) | 0.0735 |
| 6-MWD †, m | 292.3 (104.6) | +43.2 (53.6) ** | 243.2 (117.0) | +56.8 (65.8) *** | 0.6373 |
| Incremental CPET at peak exercise | |||||
| Dyspnea, Borg scale | 6.6 (2.5) | −1.1 (2.0) | 6.3 (2.6) | −1.3 (2.2) ** | 0.8299 |
| Work rate, watts | 39 (9) | +9 (8) ** | 39 (14) | +2 (10) | 0.0183 |
| V’O2 at anaerobic threshold ††, mL·min−1 | 521.5 (152.6) | +33.6 (52.6) | 547.4 (80.0) | −31.4(51.5) * | 0.0045 |
| R | 1.04 (0.08) | +0.03 (0.08) | 1.03 (0.11) | −0.01 (0.05) | 0.0863 |
| V’E, L·min−1 | 29.3 (7.4) | +4.0 (7.3) ** | 29.8 (6.6) | −1.2 (2.5) * | 0.0008 |
| VT, mL | 986 (182) | +133 (154) *** | 1025 (258) | +15 (153) | 0.0062 |
| fR, breaths·min−1 | 31 (8) | −1 (6) | 30 (5) | −1 (6) | 0.9516 |
| Ti/Ttot | 0.37 (0.04) | +0.01 (0.04) | 0. 36 (0.07) | +0.02 (0.05) | 0.7038 |
| VD/VT | 0.37 (0.08) | −0.02 (0.04) | 0.35 (0.06) | +0.02 (0.05) * | 0.0185 |
| HR, beats·min−1 | 116 (18) | +6 (10) | 119 (20) | + 1 (16) | 0.1112 |
| O2 pulse, mL·beats−1 | 6.7 (1.2) | +0.4 (0.7) * | 6.0 (1.5) | −0.5 (0.5) **** | 0.0001 |
| SpO2, % | 90.4 (4.6) | 0 (2.5) | 89.5 (5.5) | −0.6 (3.2) | 0.4565 |
| PetCO2, mmHg | 37.8 (6.7) | +0.4 (3.2) | 37.3 (4.9) | −1.3 (3.5) | 0.1463 |
| ΔFO2, % | 2.79 (0.50) | +0.15 (0.33) | 2.91 (0.42) | −0.20 (0.30) ** | 0.0037 |
| VD-intercept/VT | 0.46 (0.20) | −0.01 (0.41) | 0.40 (0.25) | +0.01 (0.23) | 0.5701 |
| V’E/V’CO2 | 43.8 (7.8) | -1.1 (4.2) | 42.5 (7.6) | +2.6 (4.2) ** | 0.0168 |
| V’E/V’CO2-nadir | 43.3 (8.0) | −1.4 (3.1) | 42.3 (7.6) | +2.4 (4.2) ** | 0.0062 |
| V’E−V’CO2-slope | 31.7 (7.2) | +1.3 (4.0) | 34.3 (10.2) | +3.3 (4.7) ** | 0.3884 |
Data are presented as means (standard deviation). V’O2: oxygen uptake; inc.: increase; PR: pulmonary rehabilitation; FEV1: forced expiratory volume in one second; IC: inspiratory capacity; 6-MWD: six-minute walk distance; CPET: cardiopulmonary exercise testing; R: gas exchange ratio; V’E: minute ventilation; VT: tidal volume; fR: breathing frequency; Ti/Ttot: inspiratory duty cycle; VD/VT: physiological dead space/tidal volume ratio; HR: heart rate; SpO2: percutaneous oxygen saturation; PetCO2: partial pressure of end-tidal carbon dioxide; ΔFO2: difference between inspiratory and expiratory O2 concentrations; VD-intercept: VD calculated as V’E-axis intercept/fR-axis intercept, obtained from V’E vs. V’CO2 and fR vs. V’CO2 relationships (see the Methods section for details); V’CO2: carbon dioxide output; V’E/V’CO2-nadir: lowest value of the ratio between V’E and V’CO2 during exercise (see the Methods section for details); V’E–V’CO2-slope: the slope was determined by linear regression analysis of V’E to V’CO2 relationship (see the Methods for details). * p < 0.05, ** p < 0.01, *** p < 0.001, **** p < 0.0001: compared with pre-PR values (within-group difference). † The data of six-MWD from 2 patients were not obtained. ††: 27 patients (peak V’O2 inc. group, n = 11; peak V’O2 non-increase group, n = 16), whose anaerobic thresholds were obtained before and after pulmonary rehabilitation were analyzed.