Association Between the Degree of Lung Tissue Damage and Functional Capacity in Patients After COVID-19 Pneumonia

Abstract

Many COVID-19 survivors face various functional disorders. The purpose of this article was to determine the association between the degree of lung tissue damage and functional capacity of patients after COVID-19 pneumonia. Materials and methods. We examined patients (n = 264) aged 46–86 years that had suffered moderate or severe COVID-19 and undergone treatment for bilateral multisegmental pneumonia followed by rehabilitation. Functional capacity was measured using a walk test (at a normal pace to the first signs of exhaustion), taking into account heart rate (HR) and peripheral oxygen saturation (SpO2). The association between the degree of lung tissue damage and test results was analysed using simple and multiple regression analysis. Regression models included the following variables: walking distance, HR and SpO2 at rest and after the test, as well as demographic and clinical characteristics of patients. Results. At normal values of resting SpO2(96.3 ± 1.6 %) and resting HR (81.4 ± 12.1 bpm), fatigue occurred after walking the distance of 130.3 ± 96.4 m, SpO2 decreased to 93.8 ± 3.5 %, HR increased to 96.8 ± 14.0 bpm, the Borg score was 6 ± 3 points. Simple regression analysis showed a negative association of the degree of lung tissue damage with walking distance as well as with resting and after-test SpO2 and a positive association with resting HR. Multiple regression analysis indicated a tendency towards a greater decrease in walking distance and a larger increase in resting HR in men compared to women as well as an increase in walking distance and a reduction in resting HR in patients with chronic diabetes as the degree of lung tissue damage increased. Thus, greater degree of lung tissue damage is associated with decreased functional capacity in patients; however, the extent of this decrease may depend on their burdened history and sex.