ABSTRACT
Introduction: Impairment of lung function and radiological abnormalities are a major concern in COVID-19 survivors, but, as of yet, patients with persistent COVID-19-related ARDS have still not been fully characterized especially regarding long-term lung injury and development of pulmonary fibrosis. The aim of this observational study is to investigate whether long-term pulmonary injury is related to fibroproliferative responses during ICU stay. Method(s): Twenty-eight PCR confirmed COVID-19 patients admitted to the ICU of the Amsterdam University Medical Centers (Amsterdam UMC), location VUmc, who underwent a diagnostic bronchoscopy with broncho-alveolar lavage (BAL) because of non-resolving COVID-19 related ARDS, were included. Bronchoscopy was repeated weekly when no clinical improvement was observed. Markers for epithelial injury and fibroproliferation were measured in BALF and plasma using specific Luminex assays or ELISA. Three and 12 months after hospital discharge, chest CT and lung function parameters were obtained during outpatient visits. Result(s): Pulmonary markers for epithelial injury and fibroproliferation were measured in BALF and compared to healthy controls (HC). Epithelial injury and fibroproliferation markers were significantly increased in critically ill COVID-19 patients as compared to HC. Plasma markers for fibroproliferation were not different as compared to HC. No signs of pulmonary fibrosis were found at 3 and 12 months after hospital discharge. Conclusion(s): Patients with non-resolving COVID-19 related ARDS show a sustained alveolar fibroproliferative response, however such fibroproliferative response is not associated with pulmonary fibrosis.