Impacto da COVID longa na capacidade funcional e na qualidade de vida: um estudo caso-controle

Abstract

Introduction: COVID-19, caused by the SARS-CoV-2 virus, was first identified in Wuhan, China, in late 2019 and rapidly spread worldwide, causing a global pandemic. Although most patients recover from the acute phase, a significant number continue to experience persistent symptoms, known as long COVID. This study aims to assess differences in cardiopulmonary exercise testing (CPET) responses between patients with and without dyspnea, 38 months after initial COVID-19 infection. Methods: A cross-sectional case-control clinical study was conducted involving individuals of both sexes, aged over 18 years, who were hospitalized for more than 24 hours due to COVID-19. Participants were divided into two groups: with and without dyspnea, based on the Modified Dyspnea Scale (mMRC). Assessments included clinical examination, lung function assessment (manovacuometry and spirometry), cardiopulmonary exercise testing (CPET), near-infrared spectroscopy (NIRS), and quality of life questionnaire (SF-36). Results: The dyspnea group had significantly lower peak VO2 and % predicted VO2, as well as lower peak power and peak VE, compared to the group without dyspnea. There were no significant differences in lung function variables between the groups. Tissue oxygen saturation (StO2) during exercise was lower in the dyspnea group. In addition, quality of life, measured by the SF-36 questionnaire, was lower in the dyspnea group, especially in the functional capacity and general health status domains. Correlation analysis revealed a significant relationship between the chronotropic index and % predicted VO2, highlighting the importance of chronotropic competence in the functional capacity of these patients. Respiratory variables, such as maximum expiratory pressure (MEP) and % predicted MEP, correlated positively with peak VO2 and % predicted VO2. Furthermore, time to reach minimum tissue oxygen saturation during exercise and muscle oxygen consumption (muscle VO2) showed significant positive correlations with % predicted VO2. Conclusion: Patients with persistent dyspnea 38 months after initial COVID-19 infection have reduced functional capacity, worse quality of life, and impaired muscle oxygenation during exercise. These findings highlight the importance of rehabilitation strategies focused on improving autonomic, cardiovascular, pulmonary functions, and aerobic capacity in these individuals.