PULMONARY FUNCTION EXAMINATION IN PATIENTS AFTER SEVERE COVID- 19 PNEUMONIA

Abstract

Covid-19 virus (SARS-CoV-2) came unexpectedly to the world population and affected more than 644
million people (confirmed cases) as of November 24th, 2022. Bulgaria is also among the affected countries with
nearly 1,300,000 people of which 38,000 have resulted in death. In the coming years, Covid-19 is expected to have a
major impact on the physical, cognitive, mental and social health of those affected, even with a mild form of the
disease. A large proportion of patients develop Covid-19-associated pneumonia, which is usually bilateral,
interstitial pneumonia, characterized with typical "ground-glass" appearance on CT scan. Autopsies performed on
patients who died of severe Covid-19 infection showed the presence of diffuse alveolar damage (present in ARDS),
but with a significant prevalence of thrombus formation in the pulmonary capillaries. A significant number of
hospitalized patients develop severe Covid-19 pneumonia (evidence of pneumonia, plus one of the following:
respiratory rate >30 breaths/min; severe distress syndrome; or saturation (SpO2) ≤93% at rest). They have the need
for supplemental oxygen. All these data raise interest about the long-term consequences of this disease.
The aim of the study is to determine the changes in lung function indicators in patients who experienced a severe
form of Covid-19 pneumonia.
A total of 35 patients between the ages of 44 and 67, examined between the second and sixth month of the acute
illness, took part in the study. All patients were hospitalized with severe Covid-19 pneumonia without evidence of
previous lung disease. A low saturation value (Sp02<90%) was reported during the hospital stay and a normal
saturation at discharge. In this regard, we performed blood gas analysis of the patients, which showed normal pO2
values.
An objective assessment of lung function can be given by tests such as spirometry and lung diffusion capacity. The
largest percentage of patients had disturbances related to damage in the diffusion capacity of the lung. The indicator
that undergoes the most serious change after the Covid-19 infection is DLco. It measures the ability of the lungs to
transport gas from inhaled air to the erythrocytes in the pulmonary capillaries. The performed spirometry of these
patients did not show significant changes of restrictive or obstructive type. A subset of patients underwent a sixminute
walk test (6MWT), in which slight desaturation was observed with rapid recovery.
In conclusion, the diffusion capacity of the lungs is severely altered after severe infection with Covid-19 and may
serve as an indicator for pulmonary parenchymal recovery.