Table 3.

Changes in incremental exercise parameters at peak exercise after pulmonary rehabilitation

	Time only-increased group (n=18)		Two factors-increased group (n=11)		P-value between groups
	Pre-PR	Difference	Pre-PR	Difference
Dyspnea, Borg scale	6.6±2.2	−1.3±2.2*	6.5±2.7	−1.7±1.8*	0.663
${\dot{\mathrm{V}}\mathrm{O}}_2$, mL⋅min−1	739±213	−65±39****	730±208	82±52***	<0.0001
Exercise time, sec	421±173	72±71***	465±171	124±57****	0.050
Time–slope, sec⋅mL−1⋅min	0.93±0.33	0.28±0.22****	0.94±0.14	0.07±0.15	0.011
F, breaths⋅min−1	30.3±5.8	−1.2±6.9	30.1±4.5	−0.9±6.2	0.903
VT, mL	1,072±297	29±169	1,086±322	164±160**	0.043
${\dot{\mathrm{V}}}_{\mathrm{E}}$, L⋅min−1	31.4±7.4	−0.7±2.8	32.6±11.2	3.6±4.6*	0.004
${\dot{\mathrm{V}}\text{CO}}_2$, mL⋅min−1	768±260	−69±56****	773±273	114±73***	<0.0001
R	1.03±0.12	0.00±0.06	1.04±0.10	0.03±0.05	0.182
VD/VT	0.35±0.06	0.01±0.05	0.35±0.08	−0.02±0.04	0.137
${\dot{\mathrm{V}}}_{\mathrm{E}}$/ ${\dot{\mathrm{V}}\mathrm{O}}_2$	43.4±5.2	3.6±4.3**	44.8±9.5	−0.1±4.5	0.034
${\dot{\mathrm{V}}}_{\mathrm{E}}$/ ${\dot{\mathrm{V}}\text{CO}}_2$	43.0±7.7	3.5±4.4**	43.0±8.0	−1.4±4.2	0.006
ΔFO2, %	2.88±0.35	−0.31±0.25****	2.82±0.55	0.17±0.33	0.0002
Ti/Ttot	35.3±7.4	2.7±5.2*	38.5±5.6	0.5±4.0	0.228
HR, beats⋅min−1	121.1±19.4	1.4±17.3	120.3±19.2	5.5±11.7	0.504
${\dot{\mathrm{V}}\mathrm{O}}_2$/HR, mL⋅beats−1	6.2±1.7	−0.7±0.4****	6.0±1.0	0.4±0.5*	<0.0001
SpO2, %	90.2±5.9	−0.5±3.4	90.6±4.7	−0.9±3.9	0.779

Notes: Data are presented as mean ± SD. The data of 33 patients were obtained from CPET performed under room air conditions, that is, FiO₂ =21%. The FiO₂ of two patients was 24%, and the FiO₂ of one patient was 30%.

^*P<0.05,

^**P<0.01,

^***P<0.001,

^****P<0.001. The post-PR results were compared with the pre-PR results within each group. In the time only increased group, exercise time was increased, but the peak ${\dot{\mathrm{V}}\mathrm{O}}_2$ was economized after pulmonary rehabilitation; in the two factors increased group, both the exercise time and the peak ${\dot{\mathrm{V}}\mathrm{O}}_2$ were increased after pulmonary rehabilitation.

Abbreviations: ΔFO₂, the inspired oxygen concentration (FiO₂) minus expired oxygen concentration (FeO₂); F, breathing frequency; HR, heart rate; R, gas exchange ratio; SpO₂, oxygen saturation; T_i/T_tot, the ratio of inspiratory time to total breathing cycle time; time–slope, exercise time/ $\mathrm{\Delta }{\dot{\mathrm{V}}\mathrm{O}}_2$; ${\dot{\mathrm{V}}\text{CO}}_2$, carbon dioxide output; V_D/V_T, physiologic dead space/tidal volume ratio; ${\dot{\mathrm{V}}}_{\mathrm{E}}$, minute ventilation; ${\dot{\mathrm{V}}\mathrm{O}}_2$, oxygen uptake; V_T, tidal volume.