Published in:
01-01-2013 | Original Paper
Step climbing capacity in patients with pulmonary hypertension
Authors:
Benjamin Daniel Fox, David Langleben, Andrew Hirsch, Kim Boutet, Avi Shimony
Published in:
Clinical Research in Cardiology
|
Issue 1/2013
Login to get access
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.