Introduction
COVID-19 has infected over 70 million people since it appeared just over
a year ago in December 2019, and this number continues to grow daily.
The clinical course ranges from asymptomatic or mild (loss of smell and
taste, anorexia, muscle and joint pain, fatigue) to severe, particularly
in older patients, patients with comorbidities such as hypertension,
diabetes mellitus, or chronic kidney disease, pregnant women, and
immunocompromised patients 1.
Acute respiratory failure and macrophage activation syndrome are the
most common severe clinical manifestations of COVID-19. Both are
characterized by overproduction of proinflammatory cytokines which can
lead to endothelial dysfunction in several vital organs, especially the
lungs. Recent studies have shown that COVID-19 causes extensive alveolar
epithelial destruction, capillary damage/bleeding, hyaline membrane
formation, alveolar septal fibrous proliferation, and pulmonary
consolidation. Pulmonary function tests have been the most concrete
indicator of this lung damage 2,3.
Studies involving 2-year follow-up of pulmonary function values in
patients with severe acute respiratory syndrome (SARS) and Middle East
respiratory syndrome (MERS) demonstrated that the main pathology was
reduced diffusion capacity (15.5–43.6%), followed by decreased total
lung capacity (5.2–10.9%) 4,5. It was also reported
that pulmonary function tests performed at discharge revealed no
significant difference in forced expiratory volume in the first second
(FEV1) or forced vital capacity (FVC) values between
COVID-19 patients with mild, moderate, and severe pneumonia, whereas
diffusion capacity decreased in correlation with disease severity.
Pulmonary function testing is often not recommended for patients with
active COVID-19 infection in order to prevent excessive transmission6. However, despite clinical improvement in this
patient group, ongoing hypoxia and persistent radiological findings
cause considerable difficulty in predicting the extent of improvement in
pulmonary function.
The aim of this study was to determine the relationship between
pulmonary function tests and laboratory parameters for the demonstration
of pulmonary dysfunction, which is an important problem for COVID-19
patients.