Prognostic value of blood gas analyses in patients with idiopathic pulmonary arterial hypertension

• Published in: The European respiratory journal Vol. 29; no. 5; pp. 944 - 950
• Main Authors: Hoeper, M. M, Pletz, M. W, Golpon, H, Welte, T
• Format: Journal Article
• Language: English
• Published: Leeds Eur Respiratory Soc 01-05-2007; Maney
• Subjects: Area Under Curve; Biological and medical sciences; Blood Gas Analysis; Cardiac Output, Low; Female; Humans; Hypertension, Pulmonary - mortality; Hypertension, Pulmonary - physiopathology; Logistic Models; Male; Medical sciences; Middle Aged; Oxygen Consumption; Pneumology; Predictive Value of Tests; Prognosis; Pulmonary Gas Exchange; Pulmonary hypertension. Acute cor pulmonale. Pulmonary embolism. Pulmonary vascular diseases; Respiratory Function Tests; Retrospective Studies; ROC Curve; Survival Rate; Human; Blood gas; Oxygen; Blood gases; Respiratory disease; Carbon dioxide; Idiopathic; Cardiovascular disease; Patient; Gas analysis; Artery; Pulmonary hypertension; Blood; Predictive value; Hypoxia; Hyperventilation; Pneumology
• ISSN: 0903-1936; 1399-3003
• DOI: 10.1183/09031936.00134506

Blood gas abnormalities in patients with idiopathic pulmonary arterial hypertension (IPAH) may be related to disease severity and prognosis. The present authors performed a 12-yr retrospective analysis assessing arterialised capillary blood gases, haemodynamics, exercise variables and survival in 101 patients with IPAH. At baseline, arterial oxygen tension (P(a,O(2))) and carbon dioxide arterial tension (P(a,CO(2))) were 9.17+/-1.86 and 4.25+/-0.532 kPa, respectively. While P(a,O(2) )was not associated with survival, a low P(a,CO(2 ))was a strong and independent prognostic marker. When patients were divided according to a baseline P(a,CO(2 ))value above or below 4.25 kPa, a cut-off value determined by receiver operating characteristics analysis, survival rates were 98 and 86% at 1 yr, 82 and 69% at 2 years, 80 and 51% at 3 yrs, 77 and 41% at 5 yrs, and 65 and 12% at 8 yrs, respectively. P(a,CO(2 ))after 3 months of medical therapy was strongly associated with survival. Hypocapnia at rest and during exercise correlated with low cardiac output, low peak oxygen uptake and reduced ventilatory efficacy. Multiple regression analysis revealed that 6-min walking distance, right atrial pressure and P(a,CO(2 ))were independently associated with survival. In patients with idiopathic pulmonary arterial hypertension, hypocapnia (carbon dioxide arterial tension <4.25 kPa) is an independent marker of mortality.