Abnormal pulmonary arterial pressure limits exercise capacity in patients with COPD.
OBJECTIVE
Pulmonary hypertension (PH) is common in patients with chronic obstructive pulmonary disease (COPD). Mean pulmonary artery pressure (mPAP) is often only slightly elevated at rest but is increased by exercise. The purpose of this study was to determine whether abnormal pulmonary artery pressure impairs exercise capacity in patients with COPD.


METHODS
42 patients with moderate-to-very-severe COPD (28 men, 14 women) underwent symptom-limited incremental cardiopulmonary exercise testing and also right-heart catheterization at rest. Abnormal pulmonary artery pressure was defined as mPAP>20 mmHg at rest.


RESULTS
Resting mPAP was elevated in 32 patients (PH, mPAP=26.8+/-5.9 mmHg) and normal in 10 non-hypertensive (NPH) patients (NPH, mPAP=16.8+/-2 mmHg). There were no significant differences in lung function between the PH and NPH groups. Maximum oxygen uptake during exercise (VO2max) was significantly lower in PH (785+/-244 ml/min) than in NPH (1052+/-207 ml/min, P=0.004). Dead-space ventilation (Vd/Vt) was greater in PH (P=0.05) with higher VE/VCO2 (ratio of minute ventilation to carbon dioxide output=47.3+/-10 vs 38.6+/-3.5, P=0.025) and significantly higher arterial-end-tidal pCO2 difference [p(a-ET)CO2]. Pulmonary vascular resistance measured at rest correlated significantly with VO2max, VE/VCO2 and p(a-ET)CO2.


CONCLUSIONS
In patients with COPD, abnormal pulmonary artery pressure impairs gas exchange, decreases maximum oxygen uptake during exercise and impairs exercise capacity.
Vonbank
Karin
K
Department of Internal Medicine II, Medical University of Vienna, Vienna, Austria. karin.vonbank@meduniwien.ac.at
Funk
Georg Christian
GC
Marzluf
Beatrice
B
Burian
Bernhard
B
Ziesche
Rolf
R
Stiebellehner
Leopold
L
Petkov
Ventzislav
V
Haber
Paul
P
D000368:Aged; D002245:Carbon Dioxide / Q000097:blood; D005080:Exercise Test; D005260:Female; D006801:Humans; D006976:Hypertension, Pulmonary / Q000503:physiopathology*; D008176:Lung Volume Measurements; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood; D029424:Pulmonary Disease, Chronic Obstructive / Q000503:physiopathology*; D011659:Pulmonary Gas Exchange; D011669:Pulmonary Wedge Pressure / Q000502:physiology; D012016:Reference Values; D012126:Respiratory Dead Space / Q000502:physiology; D014655:Vascular Resistance / Q000502:physiology; D014692:Ventilation-Perfusion Ratio / Q000502:physiology
D002245:Carbon Dioxide; D010100:Oxygen