Six minute walk distance (6MWD) and pulmonary diffusing capacity (DL_CO) in patients with COPD

Abstract

Background and Aims: Spirometry is noninvasive test for diagnosis , assessment airflow limitation and to plan management in COPD. GOLD guideline recommended to evaluate staging in airflow obstruction by post-bronchodilator FEV 1 level before treatment. FEV 1 may be correlated with dyspnea symptoms and health status but takes time to evaluate for outpatient visit .The 6-minute walk test (6MWT) is a practical simple test that requires no expensive equipment or advanced training technicians and correlates better to measure functional capacity .This study was aimed to determine correlation and efficacy between FEV 1 and 6MWD on dyspnea symptoms and functional status in COPD patients. Methods: Retrospective study conducted of 493 diagnostic COPD patients who attending outpatient department between 2014 to 2016 .All patients underwent spirometric measurement post-bronchodilator FEV 1. 6MWT was performed following American Thoracic Society (ATS) which distance was recorded in meters.Baseline characteristics ,Modified British Medical Research Council (mMRC) Questionnaire and COPD Assessment Test (CAT) were recorded and calculated .Correlation coefficient (r) analysis by Spearman rank correlation. Results: This study showed significantly linear correlation of FEV 1 (L/-min) with 6MWD(r = 0.33, P < 0.001), mMRC(r = 0.33, P < 0.001), and CAT (r = 0.22 P =0.001),otherwise there was inverse linear correlation significantly between 6MWD with mMRC(r=-0.29,P < 0.001) and CAT(r=-0.24,P < 0.001). Conclusions: 6MWD can be useful for evaluation and follow-up stable COPD patients effectively when the facility of spirometry is limited.

Underutilization of Diffusion Capacity of Lung for Carbon Monoxide in Severity Assessment and Prognostication of COPD

“…There is another study which compares exercise test with DLCO that showed a significant correlation. 5 It also depicts that exercise capacity worsens as the DLCO value decreases. A study, which we had conducted on patients with COPD also exhibited a significant correlation between the severity of COPD with various categories of DLCO (unpublished).…”