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Respir Med. 2013 Dec;107(12):1993-9. doi: 10.1016/j.rmed.2013.06.013. Epub 2013 Jul 14.

A symptom-limited incremental step test determines maximum physiological responses in patients with chronic obstructive pulmonary disease.

Author information

1
Post-Graduate Program in Rehabilitation Sciences, Universidade Nove de Julho - UNINOVE, Rua Vergueiro 235/249 - 2o subsolo, 01504-001 São Paulo, Brazil. Electronic address: simonedc@uninove.br.

Abstract

BACKGROUND:

Step tests have been used to evaluate exercise tolerance and effort-related hypoxemia in different diseases. A symptom-limited incremental step test (IST) has never been tested in COPD patients.

AIM:

To compare maximal physiological responses between an IST and cardiopulmonary exercise testing (CPET), to test the reproducibility of the IST on different days, and to provide a predict equation to estimate VO2 from the IST in patients with COPD.

MATERIAL AND METHODS:

At the same day, thirty-four patients (VEF1 46 ± 14% of pred) underwent a CPET on cycle ergometer and the first IST (IST-1) (1 h apart). After 2-5 days, patients repeated the IST (IST-2). Pulmonary gas exchange was measured during all tests.

RESULTS:

Peak VO2 was significantly higher in IST-1 and IST-2 than in CEPT (Mean ± SD: 1.19 ± 0.39 L, 1.20 ± 0.40 L, 1.07 ± 0.35 L) with no difference for ventilation (VE), heart rate (HR), and perception of effort. ISTs were highly reproducible, with significant intraclass correlation coefficient (CCI [95% confidence interval]) for number of steps (0.98[0.95-0.99]), VO2 (0.99 [0.98-0.99]), VE (0.97[0.93-0.99]), HR (0.92[0.81-0.97]), and SpO2 (0.96[0.90-0.98]). Desaturation was significantly higher for IST-1 and IST-2 compared with cycling (Mean ± SD: -6 ± 5%, -6 ± 4%, -3 ± 3%). Number of steps and patient weight explained 81% of the variance in peak VO2 (p < 0.001).

CONCLUSION:

A symptom-limited incremental step test, externally paced, elicits maximal cardiopulmonary and metabolic responses, and is well tolerated and reproducible in patients with COPD.

KEYWORDS:

COPD; Cardiopulmonary exercise test; Exercise tolerance; Field test; Oxygen uptake; Step test

PMID:
23863809
DOI:
10.1016/j.rmed.2013.06.013
[Indexed for MEDLINE]
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