Measurement of Dynamic Hyperinflation During the 6-Minute Walk Test Using a Mobile Device

Abstract

BACKGROUND: Dynamic hyperinflation is a major cause of dyspnea in patients with COPD. Dynamic hyperinflation is usually measured with cardiopulmonary exercise testing, but this test requires maximal effort from the patient, and inspiratory capacity (IC) measurements may influence test results. This study investigated another approach by measuring dynamic hyperinflation during the more natural and better-tolerated 6-min walk test (6MWT), using a mobile system for IC measurements. METHODS: Twenty subjects were studied, including 10 healthy subjects and 10 subjects with COPD. Each subject performed a pair of 6MWTs. RESULTS: The study showed that test-retest reliability in healthy subjects was excellent (intraclass correlation coefficient 0.995). In addition, mean resting IC in healthy subjects (3.27 ؎ 0.77 L) was not affected at the end of the 6MWT, whereas mean resting IC in subjects with COPD (2.45 ؎ 0.90 L) decreased to 1.93 L ؎ 0.68 L at the end of the 6MWT (P ‫؍‬ .004). The tolerability of the device for subjects with COPD appeared to be only slightly hampered by an increased sense of dyspnea attributed to wearing a mask. CONCLUSIONS: This study provides a proof of principle for mobile IC measurements during the 6MWT, demonstrating good test performance, reasonable tolerability, and a power to differentiate normal from pathologic conditions.

Gait characteristics in patients with ankylosing spondylitis: a systematic review

“…Even if this test is valid (58) and reliable (59,60) in healthy adults, the psychometric properties of these tests have not been specifically tested in patients with AS contrary to other pathologies, such as chronic obstructive pulmonary (61) or cardiac (62) diseases. Besides, no study assessed the minimal detectable change or the minimal clinically important difference on gait outcomes for patients with AS while this measure is useful for clinicians to estimate how much change in an outcome measure is clinically important and meaningful (63).…”

Lung Hyperinflation in Chronic Obstructive Pulmonary Disease: Clinical and Therapeutic Relevance

“…Although portable systems for measuring IC have been developed 17 , its assessment during exercise requires specific equipment; thus, it is expensive and accessibility is limited. As an alternative, the induction of tachypnoea has been proposed with the use of a metronome, taking IC measurements before and after hyperventilation 18,19 .…”