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Show allDevelopment of a Constant Rate Step Test to Assess Exertional Dyspnea in the Primary Care Setting in Patients with COPD Ashley Rycroft
Abstract
Background: There is a need to develop a field test to evaluate exertional dyspnea in the primary care setting. This study examined the applicability of a 3-minute constant rate step test in patients with COPD.
Methods: This test involved 4 stepping rates (18, 22, 26, 32 steps.min-1) equivalent to approximately 4.5, 5.3, 6.0, and 7.2 MET with the ultimate goal that in its final development, the assessment will be made a single stepping rate based on disease severity. Stable COPD patients (N= 43; 65 ± 6.5 years; FEV1= 49 ± 16% pred.; SpO2 (%) rest: 95± 2) were equipped with a portable Jaeger Oxycon Mobile® metabolic system and followed an audio signal for stepping up and down a single 20 cm step for 3 minutes. Borg dyspnea scores were obtained at the end each stepping bout. A 10-min rest was given between each stepping bout.
Results: O f the 43 patients, 80% completed stages 1 and 2, 74 and 37% stages 3 and 4 while no patient of MRC class 4 or 5 (n=8) completed stage 1. Breathing frequency (breaths.min-1) spanned from 26.5± 4.1 to 39.0±6.4 but VT (L) remained unchanged (1.4± 0.3 vs. 1.5±0.4) from stage 1 to 4 while Borg scores were 3 ± 1, 4 ± 1, 5 ± 2, 6 ± 3 respectively and SpO2 (%) were 92±5, 91±4, 91±4 and 90±4.
Conclusions: Preliminary findings indicate that a 3-min constant rate step test may present a feasible alternative to laboratory testing to assess exertional dyspnea in moderately severe COPD. In this population, a stepping rate of 26 steps·min-1 could be sustained by the majority of patients while producing a level of dyspnea potentially amenable to therapy.
Methods: This test involved 4 stepping rates (18, 22, 26, 32 steps.min-1) equivalent to approximately 4.5, 5.3, 6.0, and 7.2 MET with the ultimate goal that in its final development, the assessment will be made a single stepping rate based on disease severity. Stable COPD patients (N= 43; 65 ± 6.5 years; FEV1= 49 ± 16% pred.; SpO2 (%) rest: 95± 2) were equipped with a portable Jaeger Oxycon Mobile® metabolic system and followed an audio signal for stepping up and down a single 20 cm step for 3 minutes. Borg dyspnea scores were obtained at the end each stepping bout. A 10-min rest was given between each stepping bout.
Results: O f the 43 patients, 80% completed stages 1 and 2, 74 and 37% stages 3 and 4 while no patient of MRC class 4 or 5 (n=8) completed stage 1. Breathing frequency (breaths.min-1) spanned from 26.5± 4.1 to 39.0±6.4 but VT (L) remained unchanged (1.4± 0.3 vs. 1.5±0.4) from stage 1 to 4 while Borg scores were 3 ± 1, 4 ± 1, 5 ± 2, 6 ± 3 respectively and SpO2 (%) were 92±5, 91±4, 91±4 and 90±4.
Conclusions: Preliminary findings indicate that a 3-min constant rate step test may present a feasible alternative to laboratory testing to assess exertional dyspnea in moderately severe COPD. In this population, a stepping rate of 26 steps·min-1 could be sustained by the majority of patients while producing a level of dyspnea potentially amenable to therapy.
© 2007-2012 Canadian Society for Clinical Investigation.
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