title: Step climbing capacity in patients with pulmonary hypertension.
abstract: BACKGROUND
  Patients with pulmonary hypertension (PH) typically have exercise intolerance and limitation in climbing steps.
  
  
  OBJECTIVE
  To explore the exercise physiology of step climbing in PH patients, on a laboratory-based step test.
  
  
  METHODS
  We built a step oximetry system from an 'aerobics' step equipped with pressure sensors and pulse oximeter linked to a computer. Subjects mounted and dismounted from the step until their maximal exercise capacity or 200 steps was achieved. Step-count, SpO(2) and heart rate were monitored throughout exercise and recovery. We derived indices of exercise performance, desaturation and heart rate. A 6-min walk test and serum NT-proBrain Natriuretic Peptide (BNP) level were measured. Lung function tests and hemodynamic parameters were extracted from the medical record.
  
  
  RESULTS
  Eighty-six subjects [52 pulmonary arterial hypertension (PAH), 14 chronic thromboembolic PH (CTEPH), 20 controls] were recruited. Exercise performance (climbing time, height gained, velocity, energy expenditure, work-rate and climbing index) on the step test was significantly worse with PH and/or worsening WHO functional class (ANOVA, p < 0.001). There was a good correlation between exercise performance on the step and 6-min walking distance-climb index (r = -0.77, p < 0.0001). The saturation deviation (mean of SpO(2) values <95 %) on the step test correlated with diffusion capacity of the lung (ρ = -0.49, p = 0.001). No correlations were found between the step test indices and other lung function tests, hemodynamic parameters or NT-proBNP levels.
  
  
  CONCLUSIONS
  Patients with PAH/CTEPH have significant limitation in step climbing ability that correlates with functional class and 6-min walking distance. This is a significant impediment to their daily activities.
authors.affiliation: Center for Pulmonary Vascular Disease and Lady Davis Institute for Medical Research, Jewish General Hospital, McGill University, Room E-222, 3755 Cote Sainte Catherine, Montreal, QC, H3T 1E2, Canada. benjamin.fox@mcgill.ca
authors.forename: Benjamin Daniel
authors.initials: BD
authors.lastname: Fox
authors.forename: David
authors.initials: D
authors.lastname: Langleben
authors.forename: Andrew
authors.initials: A
authors.lastname: Hirsch
authors.forename: Kim
authors.initials: K
authors.lastname: Boutet
authors.forename: Avi
authors.initials: A
authors.lastname: Shimony
mesh_terms: D000203:Activities of Daily Living; D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D015415:Biomarkers / Q000097:blood; D016022:Case-Control Studies; D016009:Chi-Square Distribution; D005080:Exercise Test; D017079:Exercise Tolerance; D065627:Familial Primary Pulmonary Hypertension; D005260:Female; D006339:Heart Rate; D006801:Humans; D006976:Hypertension, Pulmonary / Q000097:blood / Q000175:diagnosis* / Q000503:physiopathology; D016014:Linear Models; D008168:Lung / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D009043:Motor Activity; D020097:Natriuretic Peptide, Brain / Q000097:blood; D010092:Oximetry; D010100:Oxygen / Q000097:blood; D010446:Peptide Fragments / Q000097:blood; D011237:Predictive Value of Tests; D012815:Signal Processing, Computer-Assisted; D016138:Walking
chemical_list: D015415:Biomarkers; D010446:Peptide Fragments; C109794:pro-brain natriuretic peptide (1-76); D020097:Natriuretic Peptide, Brain; D010100:Oxygen