Fibrotic outcomes from SARS-CoV-2 virus interstitial pneumonia

Following the onset of the new COVID-19 pandemic, particular attention is paid to the long-term outcomes, especially concerning patients affected by the SARS-CoV-2 virus leading to interstitial pneumonia. The aim of this research is to evaluate the possible evolution over time of interstitial pneumonia into post-inflammatory fibrosing interstitial disease. This research included 42 patients admitted to the COVID ward for SARS-CoV-2 interstitial pneumonia, 10 patients with mild pneumonia and respiratory failure who were treated with O₂ only, 32 patients with severe pneumonia in which O₂ and non-invasive ventilation were used for respiratory assistance, and 4 patients treated with invasive mechanical ventilation. At 70±30 days, 6, 12, 24, and 36 months after discharge, the cohort of patients carried out the evaluation of inflammation indices, high-resolution computed tomography (CT) chest scans, and functional respiratory tests. The comparative analysis showed that 83.3% of patients had residual parenchymal lung disease at 36-month follow-up, with a significantly higher rate in those with severe pneumonia and more extensive disease on initial CT. Regarding the pulmonary involvement model, patients presented ground-glass opacity or peripheral parenchymal bands, or a combination of them, peri- and intralobular interstitial thickening, which may be representative of fibrotic interstitial lung disease. There is a correlation between the severity of pneumonia, the inflammatory state, the need to increase respiratory support, and the quantity and persistence of CT-related lesions. Reductions in respiratory functions and exercise capacity were observed, the latter more pronounced in patients (24%) who had contracted severe pneumonia and required ventilatory support.Pulmonary outcomes from SARS-CoV-2 respiratory infections show a wide range of radiological findings, from complete recovery to stable outcomes of thickening and distortion of the interstitial architecture. From a functional point of view, there is an impairment of the alveolar-capillary diffusion capacity and, in cases who had contracted severe pneumonia, desaturation and reduced exercise tolerance in 24% of cases at a 36-month follow-up.