ABSTRACT
The 6-minute walk test (6MWT) is used to measure exercise capacity and assess prognosis in diffuse parenchymal lung disease (DPLD). Although the 6MWT is usually considered to be a test of submaximal exercise capacity in DPLD, the physiological load imposed by this test is not well described and 6MWT outcomes are poorly understood. This study aimed to compare cardiorespiratory responses to 6MWT in people with DPLD. Methods: An observational crosssectional study was carried out in a single tertiary care center in northern India which included 50 consecutive subjects (age >12 years) who had diffuse parenchymal lung diseases. In this study, the clinical, radiological and histological data subjects was collected. 6MWT was done of all the patients and results tabulated. Result: Desaturation on 6MWT (SPo2 <88% or fall of 4% from baseline) were seen in total of 33(66%) patients with most cases being IPF in which 17 patients (89.47%) out 19 cases showed desaturation. This was followed by NSIP with 4(67%) of of 6 cases and CTD-ILD having 7(53.8%) out of 13 cases showed desaturation. More studies are required from developing countries to ascertain the spectrum of DPLDs in different geographic. Conclusion: On average, the 6MWT elicits a high but submaximal oxygen uptake in people with DPLD. Fibrosis is associated with maximum destauration in 6MWT. However the physiological load varies between individuals, with higher peak VO2 in those with more severe disease that may match or exceed that achieved on CPET. The 6MWT is not always a test of submaximal exercise capacity in people with DPLD.