Correlation between Six Minute Walk Test and Spirometry in Chronic Pulmonary Disease

Introduction: Six minute walk test (6MWT), is an exercise test, used as a clinical indicator of the functional capacity, in patients with cardiopulmonary diseases. The present study assessed the correlation of six minute walk test with pulmonary function variables, in patients with chronic pulmonary diseases, in local population. Aims & Objectives: The objectives were to study correlation of different spirometry variables with variables of six minute walk test like percent predicted 6 minute walk distance (% Predicted 6MWD) as per Enright et al., formula and Indian reference equation, pre and post exercise pO(2) and pCO(2) and exercise desaturation. Materials and Methods: All consecutive patients with confirmed diagnosis of chronic pulmonary diseases were included from January 2013 to June 2014 in tertiary care institute. 6MWT was performed as per the ATS guidelines. Among 130 patients 108 were also subjected to arterial blood gases pre and post test. Spirometry was performed as per ATS guidelines. Percent (%) predicted 6MWD was calculated. Correlation between spirometry and 6MWT was assessed. Results: One hundred and thirty patients with chronic pulmonary disease were taken. Out of them there was 102 patients with obstructive airway disease and 58 patients with interstitial lung disease. FEV1 significantly correlated with % predicted 6MWD & with basal pO(2) and pCO(2) and with post exercise pCO(2) and pO(2). FVC also correlated with % predicted 6MWD, with basal pO(2) and pCO2 and post exercise pO(2). FEV1/ FVC correlated only with post exercise pCO(2) while MVV correlated with % predicted 6MWD and only basal pCO(2). Exercise desaturation correlated only with FVC. Percent predicted 6MWD also correlated with basal pO(2) & post exercise pO(2). Conclusion: Thus significant correlation found between 6MWT & spirometry variables (FEV1, FVC, MVV & FEV1/ FVC).