title: Abnormal pulmonary arterial pressure limits exercise capacity in patients with COPD.
abstract: 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.
authors.affiliation: Department of Internal Medicine II, Medical University of Vienna, Vienna, Austria. karin.vonbank@meduniwien.ac.at
authors.forename: Karin
authors.initials: K
authors.lastname: Vonbank
authors.forename: Georg Christian
authors.initials: GC
authors.lastname: Funk
authors.forename: Beatrice
authors.initials: B
authors.lastname: Marzluf
authors.forename: Bernhard
authors.initials: B
authors.lastname: Burian
authors.forename: Rolf
authors.initials: R
authors.lastname: Ziesche
authors.forename: Leopold
authors.initials: L
authors.lastname: Stiebellehner
authors.forename: Ventzislav
authors.initials: V
authors.lastname: Petkov
authors.forename: Paul
authors.initials: P
authors.lastname: Haber
mesh_terms: 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
chemical_list: D002245:Carbon Dioxide; D010100:Oxygen