State of Oxygen Metabolism, Cardiovascular and Respiratory System Reserve Capacity in Patients Who Underwent COVID-19

After an interview about the possibility of taking part in the study, the patient is presented with an informed consent form, explaining all the questions of interest. In the case of consent to participate in the study, the patient and the researcher fill out all the necessary fields of the two copies of the informed consent and sign it. If necessary, the researcher re-explains any information about the study. One copy of the informed consent remains with the patient, and the second copy is kept by the investigator, as required by Good Clinical Practice.

Once informed consent is obtained, an Individual Registration Card (IRC) is completed for the patient enrolled in the study. Completion of the IRC also continues until completion of the second phase of rehabilitation.

Pulmonary functional tests, cardiopulmonary stress testing (CPT) are performed on day 1 or 2 of inclusion of the patient in the rehabilitation program of "Federal Research Center for Fundamental and Translational Medicine" (FRC FTM) using MasterScreen Pneumo (Jaeger, Germany) and Oxycon Pro ergospirometry systems (Jaeger, Germany), in accordance with international standards. The indexes of external respiration are brought to BTPS conditions, and gas exchange - STPD. The protocol of stress testing is chosen individually, based on the proper values in accordance with the age, sex and anthropometric data of the patient. The study is conducted up to the individual maximum, followed by a recovery period. The anaerobic threshold is determined using the V-slope method. After peak load is reached, it is gradually reduced. Observation is continued until complete recovery of hemodynamic parameters, gas exchange, in case of adverse symptoms - until their disappearance. Repeated testing is performed after the rehabilitation program, before discharge from the FTC MTF.

Thoracic MSCT is performed on day 1-2 of inclusion of a patient into the rehabilitation program of the FRC FTM to assess the lesion of the bronchopulmonary system after COVID-19.

Questionnaires describing the severity of the underlying disease (mMRC respiratory impairment scale, BODE pulmonology risk scale, SMRT-CO respiratory support need scale), and SF-36 quality of life questionnaire are completed at study inclusion and after the rehabilitation program, before discharge from the FRC FTM.

• Spirography and assessment of pulmonary diffusion capacity (Diagnostic test): Using the Master Screen Body device you will be asked to take two series of breaths through a special tube for 2-3 minutes. Usually the procedure does not cause any discomfort
• Cardiopulmonary stress test (Diagnostic test): The exercise test is performed on a bicycle ergometer Oxycon Pro. Prior to the test, special sensors for recording the electrocardiogram, a sensor to determine blood saturation, and a cuff to measure blood pressure will be glued on the body. Breathing during the test takes place through a face mask with a built-in gas analyzer sensor. The stress test is conducted up to an individual maximum (according to the age, sex, height and weight of the patient), followed by a recovery period. There is some temporary discomfort associated with performing physical activity. Dyspnea, leg fatigue, and dizziness may occur. Observation continues until full recovery of hemodynamic and gas exchange parameters, in case of appearance of unfavorable symptoms - until their disappearance.
• Computed tomography of the chest organs (Diagnostic test): CT is a method of examination based on X-rays, but unlike conventional X-rays, it gives the most complete picture of the body structure, with less radiation. Tomography usually does not cause any unpleasant feelings and is performed in a specialized department.
• Heart echocardiography (Diagnostic test): It's a specific method of ultrasound examination, which consists in examining the heart in real time and usually does not cause any unpleasant feelings
• SF-36 Quality of Life Questionnaire (Other): https://clinmedjournals.org/articles/jmdt/jmdt-2-023-figure-1.pdf
• Demographic and antropometric measures (Diagnostic test): Age, sex, height. weight, body mass index (BMI)
• Indicators characterizing the severity of the underlying disease (Other): * Severity of underlying disease (mMRC, BODE, SMRT-CO Respiratory Support Need Scale), and comorbidities (cardiovascular disease, diabetes mellitus, chronic obstructive pulmonary disease, chronic kidney disease) * Medications taken.

Primary outcomes

• Need for respiratory support according to SMRT-CO criteria. [From enrollment to the end of treatment at 4 to 6 weeks]: The SMART-COP Score for Pneumonia Severity predicts need for intensive respiratory or vasopressor support in community-acquired pneumonia.

Secondary outcomes

• Peak oxygen consumption [From enrollment to the end of treatment at 4 to 6 weeks]: Maximum oxygen consumption is the highest amount of oxygen, expressed in milliliters, that a person can consume in 1 minute.
• Diffusion capacity of the lungs [From enrollment to the end of treatment at 4 to 6 weeks]: Diffusing capacity is a measure of how well oxygen and carbon dioxide are transferred (diffused) between the lungs and the blood, and can be a useful test in the diagnosis and to monitor treatment of lung diseases.
• Quality of life as measured by the SF-36 questionnaire [On enrollment, after 3 and 6 months from the end of rehabilitation program]: The 36-Item Short Form Survey (SF-36) is an outcome measure instrument that is often used, well-researched, self-reported measure of health. It stems from a study called the Medical Outcomes Study for the objective measure of the quality of life.

Sex: All, ages: 18 Years to any

Inclusion Criteria:

* pneumonia or acute respiratory distress syndrome caused by SARS-CoV-2
* referral for a second phase of rehabilitation
* signed informed consent of the patient to participate in the study

Exclusion Criteria:

* mental and/or locomotor disorders that make it impossible to adequately perform an exercise test, cooperate with the patient, and interpret the results
* conditions and diseases requiring emergency surgical intervention and/or observation and treatment in the ICU
* patient's refusal to participate in this clinical trial at any stage of the study.

• Oksana Kamenskaya, PhD, MD, Principal investigator, Meshalkin National Research Center