Functional diagnostics of the respiratory system in patients with Long COVID

Abstract

Given the considerable number of people with persistent respiratory symptoms more than 4 weeks after
COVID-19, it is important to determine which examinations are most informative for assessing respiratory function,
prognosis, and monitoring the effectiveness of treatment in such patients. The purpose of this study is to cover the
functional diagnosis of the respiratory system in patients who survived Long COVID. Bibliosemantic and analytical
research methods were applied. According to the world guidelines for patients with persistent respiratory symptoms
after COVID-19, all of them should undergo respiratory system examinations: chest X-rays, spirometry, blood saturation
measurements, lung diffusion capacity for carbon monoxide, walk tests, and others. The study confirmed that people
who have had COVID-19, even after 1-6 months, show a decrease in diffusing capacity of the lung for carbon monoxide,
which has a direct correlation with total lung capacity, the severity of clinical manifestations, and the results of rapid
tests. Changes in spirometric parameters are observed much less frequently, mainly in patients hospitalised with severe
pneumonia, which subsequently leads to post-cystic pulmonary fibrosis. Gradual improvement in functional respiratory
tests occurs 3 months, 6 months, and 12 months after acute infection. The most informative tests for assessing respiratory
function include the measurement of carbon monoxide diffusion capacity, total lung capacity, and blood gas composition.
In conditions of limited access to the aforementioned diagnostic tests, and as a screening tool, quick tests such as the
3-minute/6-minute walk test (3MWT/6MWT) or the 1-minute sit-to-stand test (1-MSTST) can be utilised based on the
patient's capabilities

Received: 29.03.2023 | Revised: 27.05.2023 | Accepted: 26.06.2023