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Clin Res Cardiol. 2013 Jan;102(1):51-61. doi: 10.1007/s00392-012-0495-4. Epub 2012 Aug 9.

Step climbing capacity in patients with pulmonary hypertension.

Author information

1
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

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, 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.

PMID:
22875547
DOI:
10.1007/s00392-012-0495-4
[Indexed for MEDLINE]

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