title: Hypoxic pulmonary vasoconstriction in systemic sclerosis and primary pulmonary hypertension.
abstract: Reduction of pulmonary vascular resistance by a high inspired oxygen concentration is a common, but not universal phenomenon in patients with pulmonary vascular disease of varying etiology that may determine their response to long-term domiciliary oxygen therapy. We therefore determined changes in PVR during oxygen therapy in two patient populations not previously studied: systemic sclerosis (n = 8, mean age +/- SEM, 44.5 +/- 5.4 years) and primary pulmonary hypertension (n = 7, mean age +/- SEM 38 +/- 7.8 years). All patients were hypoxemic (arterial oxygen tension, on air 9.5 +/- 1.2 kPa for SSc and 8.3 +/- 0.6 kPa for PPH, p greater than 0.05). Right atrial pressure, pulmonary artery pressure, pulmonary artery occlusion pressure, systemic arterial pressure, PaO2 and cardiac output by thermodilution were measured at three, 20-min intervals while inspiring air and again after inspiring 60 percent oxygen for 30 min. The PVR fell significantly with oxygen in patients with SSc from 797.6 +/- 179.2 to 610 +/- 151.6 dynes/s/cm-5 (p less than 0.01), and this fall correlated with baseline PAP and PaO2 prior to oxygen therapy (r = 0.86, p less than 0.025; r = 0.77, p less than 0.05, respectively). In patients with PPH, there was no significant fall in PVR with oxygen (from 969 +/- 80.2 to 851.9 +/- 91.2 dynes/s/cm-5, p greater than 0.05) and no predictor of a vasodilator response in individual patients. In SSc, hypoxic pulmonary vasoconstriction contributes more consistently to elevated PVR than in patients with PPH.
authors.affiliation: Department of Thoracic Medicine, National Heart and Lung Institute, London, England.
authors.forename: J M
authors.initials: JM
authors.lastname: Morgan
authors.forename: M
authors.initials: M
authors.lastname: Griffiths
authors.forename: R M
authors.initials: RM
authors.lastname: du Bois
authors.forename: T W
authors.initials: TW
authors.lastname: Evans
mesh_terms: D000328:Adult; D001794:Blood Pressure / Q000502:physiology; D002245:Carbon Dioxide / Q000097:blood; D002302:Cardiac Output / Q000502:physiology; D005260:Female; D006801:Humans; D006976:Hypertension, Pulmonary / Q000503:physiopathology*; D000860:Hypoxia / Q000097:blood / Q000503:physiopathology; D008168:Lung / Q000098:blood supply*; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood; D010102:Oxygen Inhalation Therapy; D011651:Pulmonary Artery / Q000503:physiopathology; D012595:Scleroderma, Systemic / Q000503:physiopathology*; D014655:Vascular Resistance / Q000502:physiology; D014661:Vasoconstriction / Q000502:physiology
chemical_list: D002245:Carbon Dioxide; D010100:Oxygen