The aim of the study was to investigate the content of cystatin C, indicators of arterial stiffness and echocardiography parameters in patients with respiratory diseases.

Methods. A total of 138 patients aged 22 to 85 years with respiratory diseases were examined (90 – chronic obstructive pulmonary disease (COPD), 48 – bronchial asthma (BA)). Echocardiographic examination (EchoCG), registration of arterial stiffness parameters, lipid profile test, and kidney function tests were performed. The glomerular filtration rate (GFR) was calculated in all patients using the cystatin C concentration according to the F.Hoek method.

Results. In the subgroup of patients with COPD compared with BA patients, the median cystatin C plasma concentration was significantly higher [1.26 (1.11; 1.47) mg/L vs 1.17 (0.91; 1.24) mg/L; p < 0.05)], the estimated GFR was significantly lower [59.4 (50.3; 68.0) mL/min vs 64.3 (60.1; 83.4) mL/min; p < 0.05)], the median vascular age [17.30 (4.80; 26.30)% vs 8.95 (0.10; 21.80)%; p < 0.05)] and the vascular age itself [58.0 (50.0; 68.0) years vs 50.00 (42.00; 61.00) years; p < 0.05)] were significantly higher. The cystatin C index positively correlated with the size of the left atrium, signs of left ventricular hypertrophy, indicators of diastolic dysfunction of the ventricles, systolic excursion of the tricuspid annulus, and systolic pulmonary arterial pressure.

Conclusion. The population of patients with respiratory diseases is characterized by a high incidence of comorbidities. An increase in plasma cystatin C concentration, a decrease in HDL cholesterol, inhibition of GFR, and an increase in arterial stiffness contribute to the development of cardiorenal relationships in COPD.

These guidelines incorporate the recent advances in chronic cough pathophysiology, diagnosis and treatment. The concept of cough hypersensitivity has allowed an umbrella term that explains the exquisite sensitivity of patients to external stimuli such a cold air, perfumes, smoke and bleach. Thus, adults with chronic cough now have a firm physical explanation for their symptoms based on vagal afferent hypersensitivity. Different treatable traits exist with cough variant asthma (CVA)/eosinophilic bronchitis responding to anti-inflammatory treatment and non-acid reflux being treated with promotility agents rather the anti-acid drugs. An alternative antitussive strategy is to reduce hypersensitivity by neuromodulation. Low-dose morphine is highly effective in a subset of patients with cough resistant to other treatments. Gabapentin and pregabalin are also advocated, but in clinical experience they are limited by adverse events. Perhaps the most promising future developments in pharmacotherapy are drugs which tackle neuronal hypersensitivity by blocking excitability of afferent nerves by inhibiting targets such as the ATP receptor (P2X3). Finally, cough suppression therapy when performed by competent practitioners can be highly effective. Children are not small adults and a pursuit of an underlying cause for cough is advocated. Thus, in toddlers, inhalation of a foreign body is common. Persistent bacterial bronchitis is a common and previously unrecognised cause of wet cough in children. Antibiotics (drug, dose and duration need to be determined) can be curative. A paediatric-specific algorithm should be used.

Aim. Аnalysis of the efficacy and safety of complex therapy including fixed-dose combinations of long-acting bronchodilators (FCLB) in comorbid patients with an exacerbation of chronic obstructive pulmonary disease (COPD) of the spirometry grades III – IV and hypertension.

Methods. A total of 232 patients with an exacerbation of COPD of the spirometry grades III – IV were examined. 174 (75%) patients were diagnosed with the third grade (GOLD III), 58 (25%) – with the fourth spirometry grade (GOLD IV). In the GOLD III group, a moderate exacerbation was diagnosed in 22 (12.6%), severe — in 152 (87.4%). In the GOLD IV group, a moderate exacerbation was diagnosed in 5 (8.5%), severe — in 53 (91.5%), respectively. The patients were divided into 4 groups. Group 1 included 50 patients with an exacerbation of COPD of the spirometry grades III – IV without hypertension; Group 2 – 56 patients with an exacerbation of COPD and concomitant hypertension; Group 3 – 64 patients with an exacerbation of COPD without hypertension, who received FCLB in addition to standard therapy from the 3rd day of hospitalization; Group 4 – 62 patients with an exacerbation of COPD of the spirometry grades III – IV and concomitant hypertension who received FCLB in addition to standard therapy from the 3rd day of hospitalization. The examination included clinical and instrumental methods: the changes in the clinical signs and symptoms, the dyspnea index (according to the mМRS scale), the saturation of hemoglobin with oxygen (SaO₂), spirometry, heart rate variability, the frequency and nature of arrhythmias, and systolic and diastolic blood pressure (BP).

Results. A sympathicotonic disorder of the autonomic balance was revealed in patients with exacerbation of COPD of the spirometry grades III – IV. This tendency intensified in the patients with concomitant hypertension, which indicated an additional negative effect of comorbid hypertension on the studied parameters. Aggravation of sympathicotonia could be a trigger for an increase in ectopic rhythm disturbances, including high-grade ventricular extrasystoles. In the groups with concomitant hypertension, rhythm disturbances were more frequent (p < 0.05). The inclusion of FCLB in the complex therapy of exacerbation of COPD of the spirometry grades III – IV made it possible to improve the condition of patients significantly: to reduce the dyspnea index on the mМRS scale, increase SaО₂ and FEV₁ (p < 0.05), achieve clinical improvement in COPD faster and shorten the hospitalization period. As a result of the rapid and effective relief of exacerbation of COPD, the influence of pathogenic factors on the cardiovascular system in the examined patients decreased. The addition of FCLB to the treatment COPD with and without comorbid hypertension did not have a negative effect on heart rate variability, did not aggravate rhythm disturbances, and did not destabilize the BP.

Conclusion. The positive clinical effects of the inclusion of FCLB in the complex therapy of exacerbation of COPD of the spirometry grades III – IV in patients with comorbid hypertension led to a decrease in shortness of breath, an improvement in respiratory functions, a decrease in tissue hypoxia and eliminated possible adverse events of this group of drugs.

Aim. Identification of risk factors for readmissions associated with an exacerbation of chronic obstructive pulmonary disease (COPD) followed by evaluation of quality of the medical care in the outpatient and hospital settings.

Methods. A retrospective analysis of the medical records of patients with an exacerbation of chronic obstructive pulmonary disease admitted to the multidisciplinary hospitals in Kazan from January 1, 2015 to December 31, 2018, was.

Results. The identified risk factors for readmission were male gender (relative risk (RR) 3.49; 95% confidence interval (CI) 1.45 – 8.43; p < 0.05), age over 70 years (RR 1.21; 95% CI 0.74 – 1.86; p < 0.05), smoking experience more than 40 years (RR 1.6; 95% CI 0.87 – 3.0; p < 0.05), duration of COPD at least 10 years (RR 3.48; 95% CI 2.27 – 5.34; p < 0.05), the presence of three or more concomitant diseases (RR 2.0; 95% CI 1.23 – 3.4; p < 0.05). The most significant reasons for readmissions were nonadherence in the outpatient settings, as well as defects in the therapy that was provided in the hospital and prescribed upon discharge.

Conclusion. The identified risk factors are non-modifiable in most cases, so optimizing treatment and monitoring patient adherence are of paramount importance. Also, more attention should be paid to nonpharmacological treatment in the form of maintaining physical activity, early smoking cessation and psychological rehabilitation. The revealed defects of the quality of medical care for patients with severe exacerbations requiring repeated hospitalizations indicate the need to intensify the implementation of the federal clinical guidelines on chronic obstructive pulmonary disease in the real clinical practice.

The role of low-density oxidized lipoproteins (OxLDL) in the pathogenesis of occupational chronic obstructive pulmonary disease (COPD) is not understood well enough.

The study aims to determine the serum levels of oxidized low-density lipoproteins and their relationship with lipid profile, the level of oxidative stress and level C-reactive protein in patients with occupational chronic obstructive pulmonary disease.

Methods. 116 patients diagnosed with occupational COPD and 25 patients with no respiratory diseases (comparison group) were examined. Serum levels of OxLDL was determined by solid phase enzyme-linked immunosorbent assay (ELISA) using the commercial reagent kit MDA-oxLDL from Biomedica Gruppe, Austria.

Results. Circulating OxLDL was detected in serum in a significant proportion of patients with stable occupational COPD. In most of the patients, the concentration of OxLDL was within the values observed in the comparison group or exceeded them by no more than two times. In the minority of patients with occupational COPD (16.5%), the concentration of OxLDL was high and 4 – 10 times higher than its average value in the comparison group. It can be assumed that the revealed differences in the concentration of OxLDL are due to the different degree and intensity of oxidation of low-density lipoproteins. The relationships between OxLDL and lipid metabolism, oxidative stress (OS), the antioxidant capacity of serum (AOS), and serum levels of C-reactive protein were described.

Conclusion. Serum OxLDL levels in patients with occupational COPD, the relationship between OxLDL and lipid metabolism, oxidative stress, and inflammation will provide an expanded view of the pathogenetic aspects of occupational COPD.

Over the past decades, the world has seen an increase in occupational lung diseases, the leaders being asthma and chronic obstructive pulmonary disease (COPD). The article presents the results of 5-year observation of food industry workers. Clinical functional and molecular genetic studies have been carried out to identify the frequency and severity of asthma and COPD along with the individual predisposition to pulmonary conditions.

Methods. 76 people of both sexes with the average age of 43.5 ± 3.6 years were examined on an outpatient basis. All subjects had daily contact with toxic and allergenic aerosols and organo-mineral dust. The respiratory function and the presence of bronchial hyperresponsiveness to occupational factors was assessed by spirography and peak flowmetry in response to exposure and elimination of industrial aerosols. Immunological and molecular genetic tests were performed: identification of hyposecretory alleles of the α1 -АТ gene, determination of polymorphisms of the GSTM1 and GSTT1 genes, immunoglobulin levels (IgE, IgM, IgG) and cytokine status (IL-4, -6, -8; TNF-α).

Results. During the 5-year follow-up period, there was a significant increase in the number of employees with severe respiratory symptoms – 36.8% (95% CI – 21.2–36.8; p < 0.05) and a statistically significant decrease in the respiratory function (p < 0.001). Progressive decrease in the respiratory function in healthy individuals and the appearance of new and more severe cases of asthma and COPD were registered primarily among workers with hyposecretory alleles of the α₁ -АТ gene and/or zero alleles of the glutathioneS-transferase genes (GSTM1 and GSTT1) in combination with abnormal cytokine status.

Conclusion. Individual risk factors for the development of asthma and COPD in individuals working in contact with toxic and allergenic aerosols and organo-mineral dust are hyposecretory PiMZ variant of the α₁ -АТ gene and deletions in the glutathione-S-transferase genes (GSTM1 0/0 and GSTT1 0/0) in combination with abnormal cytokine status. Long-term research results suggest the prognostic value of assessing individual sensitivity to industrial aerosols and the development of bronchopulmonary pathology.

From 30 to 43% of smoking patients with chronic obstructive pulmonary disease (COPD) cannot give up nicotine despite the diagnosis and deterioration of health. Most of the publications related to the treatment of COPD do not distinguish smoking patients into a separate group. The aim of this study is a comparative analysis of the effectiveness of long-acting muscarinic antagonists (LAMA), LAMA/long-acting β2 -agonists (LABA) in smoking patients.

Methods. The study involved 121 patients with a high degree of nicotine addiction and irreversible bronchial obstruction. All the patients continued to receive bronchodilator therapy. The respondents were divided into two groups: patients who quit smoking and patients who continued to smoke. In turn, each group was divided into two subgroups depending on the treatment – LAMA (Tiotropium 5 μg and Glycopyrronium 50 μg) and LAMA/LABA (tiotropium/olodaterol 5/5 μg and glycopyrronium/idacaterol 50/110 μg). We used the changes of FEV1 and the dynamics of CAT (COPD Assessment Test) as the comparison criteria.

Results. The results of the CAT and spirometry showed a tendency to improve in both groups, regardless of the treatment regimen. However, the improvement in symptoms and spirometry parameters were more pronounced in the group of patients who quit smoking: –1 and –11 points, respectively (p < 0.05) and 12 and 23%, respectively (p < 0.05). Comparison of the efficacy of various treatment regimens in the group of smoking patients showed there was no statistically significant difference between LAMA and LAMA/LABA neither in spirometry parameters (11.45 and 13.1%; p < 0.05), nor in the CAT scores (–1.5 and –1.67; p < 0.05). However, combination therapy (LAMA/LABA) was more effective than monotherapy (LAMA) in the group of patients who quit smoking both according to spirometry (25.5 and 13%, respectively; p < 0.05) and CAT (–12.3 and –5.9, respectively; p < 0.05). There was no statistically significant difference between the active substances both in the monotherapy group (tiotropium/glycopyrronium) and in the combination group (tiotropium/olodaterol and glycopyrronium/indacaterol).

Conclusion. According to CAT and spirometry, there was no difference between tiotropium and glycopyrronium, nor was there a difference between fixed-dose combinations of tiotropium/olodaterol and glycopyrronium/ indacaterol (both in the group of smokers and in the group of non-smokers). Smoking cessation is key to improving both spirometry and CAT results.

The aim of the study was to examine the role of COPD in the structure of respiratory diseases in HIV patients and the course of these comorbidities among hospitalized patients with HIV infection.

Methods. A continuous longitudinal retrospective study was conducted in the Holy Great Martyr George the Victorious Novokuznetsk City Clinical Hospital No.2 and included all HIV patients with respiratory diseases (n = 185) hospitalized in the therapeutic department in 2017 – 2018. About 2% of population in the Kemerovo region (with the population 2.7 million people) is known to be HIV-infected. The regional COPD incidence is 124.7/100 000.

Results. COPD was diagnosed in 19 (10.3%) of all HIV patients hospitalized with respiratory diseases. 73.7% of patients with COPD were aged ≤ 40 years, the mean age was 37.6 ± 5.0 years. All patients (100.0%) were known to have smoking and intravenous drug use as potential risk factors for the development and progression of COPD. The ART coverage was low (21.1%). 68.5% of patients with COPD had severe bronchial obstruction with a decrease in FEV1 < 50% of predicted values (GOLD grades III – IV). 73.7% of the patients were assigned to COPD group B, the rest 26.3% – to group D. In 31.6% of patients, the main cause of hospitalization was COPD itself, in 68.4% – COPD combined with other lung diseases (community-acquired pneumonias, septic embolism, tuberculosis and pneumocystosis). The CD4-lymphocyte count in cases of COPD combined with other respiratory diseases (median 214.0 cell/μl) was lower than in COPD as the only respiratory disease (median 495.5 cells/μl) (p = 0,014).

Conclusion. The socio-economic significance of both HIV-infection and COPD argues the further study of the course and treatment of COPD in persons with HIV-infection.

According to literature, lungs are affected in 25 – 60% of HIV-infected individuals. The most common opportunistic disease in this group of patients is pneumonia of various etiology. HIV-positive patients show a wide microbiological landscape of pneumonia pathogens.

The aim of the study was to determine the structure of the microflora of autopsy material obtained from the lungs of HIV-infected patients.

Methods. 83 samples of autopsy material from patients with HIV infection and 27 samples from HIV-negative patients were analyzed. The deceased were treated in the pulmonary departments of Samara with a diagnosis of community-acquired pneumonia. Due to the large variety of microorganisms recovered from the autopsy material, the microorganisms were divided into several groups: Enterobacteria, non-fermentative gram-negative bacteria, Enterococci, Staphylococci, Sterptococci, and Corynebacteria. The fungi were divided into two subgroups. The first included Candida spp., the second included other types of fungi. The tests for pneumocystis infection, Mycobacterium tuberculosis, and non-tuberculosis mycobacteria were not performed.

Results. Enterobacteria were found in 39.2%, non-fermentative gram-negative bacteria – in 27.3% and Enterococci – in 19.6% of the HIV-infected patients. Staphylococcus spp. were found in 4.2%, and Corynebacteria and Streptococci in 0.7% of those patients. Candida spp. accounted for 6.3%, other fungi were found in 2.0% of cases. Enterobacteria and non-fermentative gram-negative bacteria were found in 26.2% of HIV-negative patients. Enterococcus spp. – 21.4%, Staphylococci – 7.1%, Streptococci – 2.4% of those patients. Candida spp. 16.7% were found in 16.7% of HIV-negative patients. Enterobacteria were found significantly more often in the autopsy material from HIV-infected patients. The study shows the high importance of gram-negative flora as a causative agent of infectious lesions of the lung tissue. At the same time, we statistically confirmed an increase in prevalence of Enterobacteria in HIV-positive patients. Although these pathogens are not always detected in the sputum from HIV-infected patients with bronchopulmonary disorders, they are detected only by autopsy examination of the lung tissue.

Conclusion. Diagnosis and treatment of pneumonia in HIV-infected patients with severe immunodeficiency have a few specific features, such as increasing the frequency of sputum culture, reducing the number of errors at the preanalytical stage of collecting the biomaterial, ensuring proper conditions for its transportation to a bacteriological laboratory, improving the quality of analysis. The physicians should be aware of the possible detection of gram-negative flora as a causative agent of lung infections and the possible change of the causative agent.

Community-acquired pneumonia (CAP) is one of the most common lower respiratory tract diseases. An increase in the CAP incidence has been reported to be associated with epidemics of acute respiratory viral infections (ARVI).

Aim. Аssess clinical and epidemiological features of CAP in patients admitted to hospital during an ARVI epidemic.

Methods. A cross-sectional study included 208 patient records. Medical history, physical examination, laboratory and imaging data were analyzed. CAP severity was assessed by CRB-65 scale and the systemic inflammatory response syndrome (SIRS) criteria.

Results. Most CAP patients (75%) were of active working age; all presented signs of ARVI upon admission. Nasal mucosa diagnostic smears have revealed type A influenza viruses: H1N1 – 5 (83.3%) and H3N2 – 1 (16.7%) cases. 195 (93.8%) patients were not vaccinated against influenza. X-rays showed that unilateral (81.7%) and lobular pneumonia (55.8%) were the most common CAP types. 93.2% patients had nonsevere CAP, according to CRB-65. But 88 (42.3%) subjects qualified for SIRS upon admission. Concomitant conditions as risk factors of an adverse course of CAP were present in 89 patients (42.8%). Sputum analysis, if available, most frequently identified Streptococcus pneumoniae (23 cases or 38.9%) as a causative agent. Antibacterial drugs (ABD) used to treat CAP were ceftriaxone 206 (99%), macrolides 188 (90.4%), and fluoroquinolones 94 (45.2%). The initial antibacterial treatment regimens were: 186 (89.4%) prescriptions of ceftriaxone + macrolides, 16 (7.7%) prescriptions of ceftriaxone alone, and 6 (2.9%) prescriptions of levofloxacin. A switch between ABDs was reported in 78 (37.5%) cases, including 61 switches to fluoroquinolones. The median ABD administration duration was 10 (8 – 13) days.

Conclusion. Most of the hospitalized CAP patients were of working age and not vaccinated against influenza. Streptococcus pneumoniae was the most common causative agent. PCR (polymerase chain reaction) smear analysis was performed only in 6 patients with ARVI, which does not allow us to assess the role of viruses and viral-bacterial associations in the etiology of CAP. In spite of non-severe CAP, all hospitalizations were justified, due to multiple risk factors of unfavorable prognosis of CAP and epidemiological factors. Most patients received a combination of generation 3 cephalosporins and macrolides as the initial therapy for CAP.

Spontaneous pneumothorax is the most common acute chest disease. Often, giant bullae give the impression of the presence of air in the pleural cavity. Inadequate differential diagnosis leads to vain drainage of the pleural cavity, damage to the lung with its collapse and pneumothorax.

The aim. Analyze diagnostic and tactical mistakes in patients with pulmonary emphysema, which manifests with giant bullae, and outline the ways to prevent complications.

Methods. The analysis of the treatment of 1,636 patients with pulmonary emphysema and its complications undergoing treatment in the thoracic surgical department of the Samara Regional Clinical Hospital named after V.D.Seredavin in the period from 2001 to 2018 is presented.

Results. Giant bulla were diagnosed in 35 (2.1%) patients, 16 of them were hospitalized ungently. In 6 patients, the diagnosis of a giant bulla of the lung was correct, and the patients were referred to the thoracic surgical department. In 10 patients, a giant bulla of the lung was regarded as pneumothorax, and pleural drainage was performed before referral to the thoracic surgical department.

Conclusion. The correct interpretation of the radiological data and comparison with the clinical picture allows avoiding diagnostic errors and the associated danger and complications.

Introduction. The natural course of some interstitial lung diseases (ILD) is characterized by progressive fibrosing phenotype resembling idiopathic pulmonary fibrosis (IPF). Until recently, the antifibrotic drug nintedanib was approved for treatment of the only fibrosing ILD which was IPF. A new indication for this drug which has been registered in Russian Federation in 2021 includes other fibrosing ILDs with progressive phenotype (PF-ILDs) and ILD associated with systemic scleroderma (SS-ILD).

The aim of this publication is to describe general considerations of the decision of Multidisciplinary Expert Board on diagnosis and treatment of PF-ILDs including SS-ILD.

Results. According to the extension in nintedanib use mentioned above, the Expert Board created an algorithm for diagnosis and treatment of patients with PF-ILDs and criteria for nuntedanib administration in PF-ILDs.

Conclusion. Antifibrotic therapy is needed for patients with PF-ILDs with the failure of the stanrard therapy. In those patients antifibrotic treatment should be initiated as early as possible to better preserve the lung function.

One of the important features of the chronic obstructive pulmonary disease is the presence of concomitant chronic diseases in most of patients. And cardiovascular conditions occupy a special place among these comorbidities. The most common diseases associated with COPD are hypertension, coronary heart disease, and heart failure. They aggravate the clinical manifestations of the disease and have negative effect on the prognosis. In addition, concomitant cardiovascular conditions determine the need for a thorough safety assessment of the ongoing pharmacotherapy for COPD. Core of the treatment is bronchodilators. The priority pharmacological strategy is the use of fixed-dose combinations of long-acting β2 -agonists and long-acting anticholinergic medications.

The purpose of this review was to evaluate the safety profile of tiotropium/olodaterol in COPD.

Methods. This article presents the data obtained from studies of the safety of the use of tiotropium/olodaterol in patients with COPD and concomitant cardiovascular conditions.

Results. The studies showed no increase in the risk of cardiovascular events when using this combination in patients of this category.

Conclusion. А good safety profile of tiotropium/olodaterol was confirmed in patients with COPD and concomitant cardiovascular conditions.

The choice of drugs used to treat patients with chronic obstructive pulmonary disease (COPD) (inhaled β-agonists, M-anticholinergic drugs, inhaled corticosteroids (ICS)) in view of their interchangeability is reviewed in this article. This aspect is especially important for clinicians when choosing an effective and safe treatment for COPD and for increasing patient adherence to treatment.

The aim of this study was to assess the ratio of the number of reference (original), interchangeable, and generic drugs used in COPD.

Methods. In accordance with the Russian clinical guidelines 2018 and GOLD 2019, modern drugs for the treatment of COPD with bronchodilator and anti-inflammatory activity were selected. All trade names of the corresponding drugs for each international non-proprietary name (INN) In the State Register of Medicines website were considered. The information on the availability of reference (original) drugs and the corresponding interchangeable products, as well as their presence in the List of vital and essential drugs was analyzed.

Results. A large number of generic prodcuts are registered in the State Register of Medicines, and only a few of them are interchangeable with the corresponding reference (original) drug.

Conclusion. The analysis will help widen the doctors’ choice of interchangeable drugs in treatment of COPD with an equivalent effect and safety of reference drugs, as well as to increase the patients’ adherence to treatment.

Chronic obstructive pulmonary disease (COPD) is a highly debilitating disease that poses a significant and increasing burden on women’s health. There is an increasing amount of information about gender-related differences in risk factors and the progression of COPD. However, very little attention is paid in scientific research and practice to COPD as a significant issue of women’s health. The challenges of COPD prevention in women can be overcome by a multi-vector approach, including increasing patient awareness of the disease, reducing the risk of its occurrence and further research on gender aspects (biological and cultural) that affect the risk of development and the rate of progression of COPD. The article reviews the current literature on this issue.

The article presents a rare case of thrombosis of the pulmonary arteries branches, which developed in a patient two months after infection with the SARS-CoV-2 virus, that caused bilateral polysegmental pneumonia. The thrombosis was suspected because of a high plasma D-dimer level. Contrast-enhanced chest CT was performed to make a definitive diagnosis. The absence of blood clots in the veins of the lower extremities and pelvis allowed us to conclude that the patient did not have thromboembolism, but rather a pulmonary thrombosis in situ. Such possible causes of venousthromboembolic complications as tumors, systemic diseases of the connective tissue, and antiphospholipid syndrome were excluded based on negative tests for tumor and autoimmune diseases markers. The long-stay in the hospital was associated with the inability of the patient to maintain the normal level of blood oxygen saturation independently due to the large area of the lung damage associated with COVID-19 pneumonia and ischemia caused by thrombosis of the branches of the pulmonary arteries.