Table 3.

Cardiopulmonary exercise test characteristics at rest and during exercise in 93 patients with COPD divided into three groups by mPAP at rest and ΔmPAP/ΔCO slope

Variable	mPAPrest <25 mmHg		mPAPrest ≥25 mmHg	p-value
	ΔmPAP/ΔCO slope ≤3 mmHg/L/min	ΔmPAP/ΔCO slope >3 mmHg/L/min
	n=29	n=42	n=22
Peak load, watt	89 (23)	60 (31)*	40 (21)*,#	<0.001
${\dot{\mathrm{V}}\text{O}}_2$ peak, mL/kg/min	18.3 (4.8)	17.1 (3.9)	13.9 (3.0)*,#	0.001
${\dot{\mathrm{V}}\text{O}}_2$ peak/kg % pred.	57 (16)	59 (14)	46 (13)*,#	0.003
MVV rest, L/min¤	67 (25)	47 (21)*	34 (12)*,#	<0.001
Ventilation peak, L/min¤	53 (15)	42 (15)*	35 (12)*	<0.001
Ventilation peak % pred.	58 (17)	55 (20)	43 (15)*	0.01
Ventilatory reserve, %	16 (25)	5 (19)	−7 (19)*	0.001
$\dot{\mathrm{V}}\text{E}/{\dot{\mathrm{V}}\text{CO}}_2$ nadir	36 (7)	37 (6)	41 (8)*	0.05
$\dot{\mathrm{V}}\text{E}/{\dot{\mathrm{V}}\text{CO}}_2$ slope	35 (9)	34 (8)	32 (9)	0.53
Heart rate rest, beats/min	87 (18)	90 (16)	96 (18)	0.16
Heart rate peak, beats/min	134 (18)	134 (17)	130 (19)	0.68
O2-pulse peak mL/beat	10.9 (2.7)	8.3 (2.5)*	7.5 (2.1)*	<0.001
O2-pulse peak % pred.	72 (14)	64 (20)	55 (12)*	0.003
Systemic MAP rest, mmHg	95 (12)	95 (16)	93 (10)	0.77
Systemic MAP peak, mmHg	133 (21)	136 (28)	129 (23)	0.55
RER peak	0.96 (0.13)	0.95 (0.13)	0.90 (0.12)	0.20
PaO2 rest, mmHg	77 (11)	72 (8)	61 (11)*,#	<0.001
PaO2 peak, mmHg	74 (12)	68 (12)	50 (8)*,#	<0.001
PaCO2 rest, mmHg	39 (3)	41 (5)	44 (5)*	0.008
PaCO2 peak, mmHg	41 (5)	43 (7)	48 (8)*,#	<0.001
SaO2 rest, %¤	96 (2)	95 (2)*	92 (5)*,#	<0.001
SaO2 peak, %¤	94 (3)	93 (4)	84 (8)*,#	<0.001
pH peak	7.36 (0.03)	7.36 (0.03)	7.35 (0.04)	0.86
Lactate peak, mmol/L¤	5.6 (2.2)	5.6 (2.9)	4.1 (2.4)*,#	0.03
Lactate peak % pred.¤	75 (31)	81 (42)	57 (39)*,#	0.02

Notes: ANOVA was performed for variables with normal distribution, otherwise

^¤non-parametric Kruskal–Wallis test was performed. Values are presented as mean (standard deviation).

^*p<0.05, significantly different from mPAP_rest <25 mmHg and ΔmPAP/ΔCO slope ≤3 mmHg/L/min.

^#p<0.05, significantly different from mPAP_rest <25 mmHg and ΔmPAP/ΔCO slope >3 mmHg/L/min.

Abbreviations: mPAP, mean pulmonary artery pressure; CO, cardiac output; ${\dot{\mathrm{V}}\text{O}}_2$, oxygen uptake; pred., predicted; $\dot{\mathrm{V}}\text{E}$, ventilation; ${\dot{\mathrm{V}}\text{CO}}_2$, carbon dioxide production; O₂-pulse, oxygen pulse; MAP, mean arterial pressure; RER, respiratory exchange ratio; PaO₂, arterial oxygen tension; PaCO₂, arterial carbon dioxide tension; SaO₂, oxygen saturation; MVV, maximal voluntary ventilation.