Pulmonary Fibrosis During Severe COVID-19 Pneumonia

Medical charts of patients admitted at the Intensive Care Unit (ICU) of the European Hospital of Marseille between March 2020 and June 2021 will be collected retrospectively using electronic database. Data collected will focus on demography, clinical variables, biological analyses, lung biopsies, and chest CT scans performed during the hospital stay. Our routine protocol for COVID-19 management follows the "Coronavirus Disease 2019 (COVID-19) Treatment Guidelines" including the early use of corticosteroids (Dexamethasone) and IL-6 receptor antagonist (Tocilizumab). Additionally, we routinely perform, on a weekly basis, measurements of SARS CoV-2 viral load by PCR, SARS CoV-2 antibodies production, and biomarkers of fibrosis including hyaluronic acid (HA) and amino-terminal type I (PINP) and type III (PIIINP) peptides of procollagen. The present study aim to determine the proportion of patients encountering non-invasive criteria of pulmonary fibrosis as defined by either typical CT scan patterns (reticulation and/or bronchiectasia), or increased serum concentration of PIIINP above 16 µg/L, or increased bronchoalveolar lavage (BAL) concentration of PIIINP above 9 µg/L. A definitive diagnosis of lung fibrosis will be established according to lung pathology findings in patients for whom a lung biopsy have been performed during the hospital stay. Patients with a diagnosis of pulmonary fibrosis will be compared with those without fibrosis, both in the population of mechanically ventilated patients and in those remained spontaneously breathing. The primary end-point will be the number of days alive and free from the ventilator (ventilator-free days) at Day 90. The others outcomes of interest will be the duration of mechanical ventilation, the duration of ICU stay, the ICU mortality, the in-hospital mortality, the Day 28 mortality, and the Day 90 mortality. The present study also aims to determine the risk factors of pulmonary fibrosis occurence, focusing on mechanical ventilatory settings, daily dose of corticosteroids, and the occurence of nosocomial pneumonia with special attention to lung reactivation of herpesviridae. Finally, the relation between antibodies production and viral clearance (defined as the time to the first negative SARS CoV-2 PCR) or ICU survival will be investigated.