Changes in Physiological Variables in Patients with Diffuse Interstitial Lung Disease in the Six-minute Walk Test

Abstract

Objective: Diffuse Interstitial Lung Disease (DILD) is a pathology with a high mortality rate in Colombia as well as around the world. Linking patients to pulmonary rehabilitation programs is essential to improve their quality of life and aerobic capacity; thus, all patients perform the six-minute walk test (6-MWT). This study aimed to describe the changes in physiological and aerobic capacity-related variables in patients with DILD in the 6-MWT at admission to a pulmonary rehabilitation program and determine possible differences between patients with idiopathic pulmonary fibrosis (IPF) and other DILDs. Methods: This is a cross-sectional descriptive study on patients with DILD who performed the 6- MWT between January 2017 and February 2019. Sociodemographic, clinical, physiological, and exercise tolerance variables were taken into account at four different times of the 6-MWT: Rest time, the end, and the first and the fifth minute after the end of the test. The Human Ethics Committee endorsed the study, and all participants signed the informed consent form. Results: There were 64 patients with DILD. The average age was 60.84 years, 53.1% were female, 73.4% required home oxygen, and 53.1% had a diagnosis of IPF. There were no statistically significant differences in the heart rate (HR), respiratory rate (RR), peripheral oxygen saturation (SpO2), Borg scale, and fatigue in lower limbs at the four evaluated moments of the test for both groups of patients with DILD (p=0.000); moreover, the FEV1/FVC ratio for patients with other DILD was higher (p=0.000). The distance traveled for IPF was 339.26 ± 124.84, while for other DILDs, it was 365.63 ± 113.00 (p=0.382). Conclusions: Patients with other DILDs have better FEV1/FVC and travel longer distances with less dyspnea and fatigue than patients with IPF during the 6-MWT. Both groups' HR, RR, SpO2, Borg, and fatigue variables presented significant changes during the 6-MWT.