Lung Function, Exercise Capacity and Health-Related Quality of Life After Severe COVID-19

Background: Coronavirus disease 2019 (COVID-19) is a respiratory tract infection caused by a newly emergent coronavirus (severe acute respiratory syndrome coronavirus 2; SARS-CoV-2) that was first recognized in Wuhan, China, in December 2019. Currently, this infection reached pandemic levels causing serious diseases in 14% of cases and the potential to progress to acute respiratory distress syndrome (ARDS) with the need for invasive ventilatory support and prolonged hospitalization in intensive care units (ICU). The overall lethality is 2% and the lethality of cases admitted to the ICU varies from 26 to 50%. The medium and long-term impact in survivors of severe COVID-19 on lung function, exercise capacity and health related quality of life (HRQoL) remains to be determined.

Aims: To evaluate the early (Visit1: 2-6 months after acute disease) and late (Visit 2: 9-15 months and Visit 3: 18-24 months) effects of severe acute respiratory syndrome on lung function, exercise capacity, respiratory symptoms and HRQoL in patients with confirmed diagnosis of SARS-CoV-2 infection.

Material and methods: Prospective cohort of subjects with laboratory confirmed severe COVID-19 (respiratory rate> 30 breaths/ min; severe respiratory distress; oxyhemoglobin saturation in room air ≤93% or pulmonary involvement> 50% in chest images). Participants will perform spirometry before and after bronchodilator, lung volumes by body plethysmography, lung diffusion capacity of carbon monoxide, respiratory system resistance by impulse oscillometry and 6-minute walk test (6MWT) after 2-6 months (Visit 1) , 9-15 months (Visit 2), and 18-24 months (Visit 3) of severe COVID-19. When abnormalities in these pulmonary function tests and/or 6MWT were detected, a cardiopulmonary exercise test will be performed. Clinical, laboratory and chest image data during the severe COVID-19 hospitalization will be obtained from medical records.

The minimum sample size was estimated as 134 participants to assess at least 5 independent factors to predict lung function, HRQoL and exercise capacity at the early assessment. Notwithstanding, the investigators plan to invite to participate all survivors of severe COVID-19 admitted in hospitals of the state of Rio Grande do Sul (Brazil).

Inclusion criteria

• Previous laboratory confirmation of SARS-Cov-2 infection defined as a positive result of reverse polymerase-transcriptase chain reaction test in real-time of a sample taken by nasal and/or pharyngeal swab; and
• Severe pneumonia defined by the presence of fever or suspected lower respiratory infection, plus one of the following criteria: respiratory rate> 30 movements/min; severe respiratory distress; SpO2≤93% in room air; or pulmonary infiltrates>50% on chest imaging within 24-48hrs of acute symptoms onset; and/or
• Acute respiratory distress syndrome (ARDS) defined according to COVID-19 operational management guide of World Health Organization and classified as mild (200 mmHg <PaO2 / FiO2 ≤ 300 mmHg), moderate (100 mmHg <PaO2 / FiO2 ≤ 200 mmHg) or severe (PaO2 / FiO2 ≤ 100 mmHg). When the PaO2 is not available, SpO2 / FiO2 ≤ 315 suggests ARDS.

Exclusion criteria

• Lack of clinical stability for 2 months before inclusion (including those who remain hospitalized);
• Active respiratory tract infection (of any cause); or
• Any clinical condition that prevents the performance of the study procedures.