What factors alter 6-minute walk test parameters after Covid-19 respiratory infection?

Abstract

<bold>Introduction:</bold> Covid-19 infection causes many respiratory limitations, including exercise intolerance. This study aims to determine the factors that alter 6-minute walk test (6MWT) after Covid-19 infection. <bold>Methods:</bold> 6MWT was performed on patients 3 months after Covid-19 respiratory infection. <bold>Results:</bold> This cross-sectional study included 312 patients (mean age=57.91±12.7 years; sex-ratio=1.31). Regarding Covid-19 infection, 58.33% of patients had lung involvement on CT-scan (average extent =44.34±21.26%). Six-minute walk distance (6MWD) was reduced in 53.2% of patients (mean 6MWD=506.43±116.54 m). Reduction was moderate in 46.5%, severe in 4.8% and very severe in 2.6% of patients. Mean SpO2 was 94.61±4.25% at the end of 6MWT (23.4% of patients had a decrease in SpO2). Inadequate chronotropic response was reported in 32% of patients. Based on logistic regression analysis, hospitalisation duration (OR=1.04;p=0.01), oxygen therapy duration (OR=1.04;p=0.01), mechanical ventilation duration (OR=1.10;p=0.03) and persistent dyspnoea (OR=2.03;p<10-3) were identified as risk factors for 6MWD reduction. The risk of low saturation during exercise was independently associated with radiological extent (OR=1.03;p=0.01), durations of hospitalization (OR=1.06;p<10-3), oxygen therapy (OR=1.07;p<10-3), intensive care (OR=1.04;p=0.02) and mechanical ventilation (OR=1.07;p=0.03). Persistent dyspnoea increases the risk of SpO2 decrease during 6MWT by almost 3 times (OR=2.92;p<10-3). ICU admission seems to protect from chronotropic failure (OR=0.89; p=0.04). <bold>Conclusion:</bold> This study highlights the significant impact of Covid-19 respiratory infection on 6MWT parameters, emphasizing the importance of exercise rehabilitation.