Table 4.

Changes in incremental exercise parameters at iso-time 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	−2.5±2.2***	6.5±2.7	−3.6±2.1***	0.181
${\dot{\mathrm{V}}\mathrm{O}}_2$, mL⋅min−1	739±213	−102±46****	730±208	−3±44	<0.0001
F, breaths⋅min−1	30.3±5.8	−2.8±6.8	30.1±4.5	−3.5±6.2	0.761
VT, mL	1,072±297	32±172	1,086±322	155±161**	0.067
${\dot{\mathrm{V}}}_{\mathrm{E}}$, L⋅min−1	31.4±7.4	−2.3±2.5**	32.6±11.2	−0.4±3.4	0.082
${\dot{\mathrm{V}}\text{CO}}_2$, mL⋅min−1	768±260	−117±73****	773±273	3±78	0.0003
VD/VT	0.35±0.06	0.02±0.04	0.35±0.08	−0.01±0.04	0.108
${\dot{\mathrm{V}}}_{\mathrm{E}}$/ ${\dot{\mathrm{V}}\mathrm{O}}_2$	43.4±5.2	3.5±4.2**	44.8±9.5	−0.0±4.6	0.047
${\dot{\mathrm{V}}}_{\mathrm{E}}$/ ${\dot{\mathrm{V}}\text{CO}}_2$	43.0±7.7	4.0±4.4**	43.0±8.0	−0.2±4.2	0.017
ΔFO2, %	2.88±0.35	−0.28±0.25***	2.82±0.55	0.04±0.32	0.006
Ti/Ttot	35.3±7.4	2.5±4.3*	38.5±5.6	0.5±4.8	0.246
HR, beats⋅min−1	121.1±19.4	−3.2±18.1	120.3±19.2	−3.4±13.2	0.973
${\dot{\mathrm{V}}\mathrm{O}}_2$/HR, mL⋅beats−1	6.2±1.7	−0.7±0.5****	6.0±1.0	0.2±0.8	0.0007
SpO2, %	90.2±5.9	0.5±4.0	90.6±4.7	0.6±3.5	0.969

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; SpO₂ oxygen saturation; T_i/T_tot, the ratio of inspiratory time to total breathing cycle time; ${\dot{\mathrm{V}}\text{CO}}_2$, 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.