title: Pulmonary function in primary pulmonary hypertension.
abstract: OBJECTIVE
  The study was done to ascertain the degree to which abnormalities in resting lung function correlate with the disease severity of patients with primary pulmonary hypertension (PPH).
  
  
  BACKGROUND
  Patients with PPH are often difficult to diagnose until several years after the onset of symptoms. Despite the seriousness of the disorder, the diagnosis of PPH is often delayed because it is unsuspected and requires invasive measurements. Although PPH often causes abnormalities in resting lung function, these abnormalities have not been shown to be statistically significant when correlated with other measures of PPH severity.
  
  
  METHODS
  Resting lung mechanics and diffusing capacity for carbon monoxide DL(CO) were assessed in 79 patients whose findings conformed to the classical diagnostic criteria of PPH and who had no evidence of secondary causes of pulmonary hypertension. These findings were correlated with severity of disease as assessed by cardiac catheterization, New York Heart Association (NYHA) class, and cardiopulmonary exercise testing.
  
  
  RESULTS
  When PPH patients were first evaluated at our referral clinic, the DL(CO) and lung volumes were decreased in approximately three-quarters and one-half, respectively. The decreases in DL(CO), and to a lesser extent lung volumes, correlated significantly with decreases in peak oxygen uptake (reflecting maximum cardiac output), peak oxygen pulse (reflecting maximum stroke volume), and anaerobic threshold (reflecting sustainable exercise capacity) and higher NYHA class.
  
  
  CONCLUSIONS
  Patients with PPH commonly have abnormalities in lung mechanics and DL(CO) levels that correlate significantly with disease severity. These measurements can be useful in evaluating patients with unexplained dyspnea and fatigue.
authors.affiliation: Division of Respiratory and Critical Care Physiology and Medicine, Department of Medicine, Research and Education Institute, Harbor-UCLA Medical Center, Torrance, CA 90509, USA.
authors.forename: Xing-Guo
authors.initials: XG
authors.lastname: Sun
authors.forename: James E
authors.initials: JE
authors.lastname: Hansen
authors.forename: Ronald J
authors.initials: RJ
authors.lastname: Oudiz
authors.forename: Karlman
authors.initials: K
authors.lastname: Wasserman
mesh_terms: D000328:Adult; D005080:Exercise Test; D005260:Female; D006439:Hemodynamics / Q000502:physiology; D006801:Humans; D006976:Hypertension, Pulmonary / Q000503:physiopathology*; D008168:Lung / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011653:Pulmonary Diffusing Capacity / Q000502:physiology; D015203:Reproducibility of Results; D012129:Respiratory Function Tests; D012146:Rest / Q000502:physiology; D012720:Severity of Illness Index