Step climbing capacity in patients with pulmonary hypertension

Benjamin Daniel Fox, David Langleben, Andrew Hirsch, Kim Boutet, Avi Shimony

Research output: Contribution to journalArticlepeer-review

Abstract

Background: Patients with pulmonary hypertension (PH) typically have exercise intolerance and limitation in climbing steps. Objectives: 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, SpO2 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 SpO2 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.

Original languageEnglish
Pages (from-to)51-61
Number of pages11
JournalClinical Research in Cardiology
Volume102
Issue number1
DOIs
StatePublished - Jan 2013

Keywords

  • Exercise pathophysiology
  • Exercise testing
  • Monitoring
  • Oxygen desaturation
  • Pulmonary arterial hypertension
  • Pulmonary hypertension

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