Clinical analysis of 6 patients with severe COVID-19 pneumonia who underwent pathological autopsy

<bold>Background:</bold> The COVID-19 pandemic had triggered a global public health emergency, with severe cases had associated with substantial morbidity and mortality worldwide. Despite advancements in treatment modalities, the precise pathological manifestations of severe COVID-19 pneumonia remain incompletely understood. <bold>Methods:</bold> Autopsies were performed on six patients diagnosed with severe COVID-19 pneumonia leading to respiratory failure between March 2020 and March 2023. Clinical data including demographics, comorbidities, and treatment history were collected. <bold>Results:</bold> Among the six cases, comprising three males and three females with an average age of 70 years, four necessitated endotracheal intubation and mechanical ventilation, while two received noninvasive positive pressure ventilation. Mechanical ventilation duration averaged 33 days. The time from symptom onset to death averaged 48 days, with respiratory failure exacerbation as the primary cause of death in all cases. Throughout the clinical trajectory, all cases exhibited mediastinal emphysema, subcutaneous emphysema, and pneumothorax attributed to lung parenchymal damage. Autopsy findings unveiled the presence of hyaline membranes, extensive parenchymal fibrosis, Masson bodies, and a combination of diffuse alveolar damage (DAD) and organizing pneumonia-like patterns. Notably, conspicuous hyaline membrane formation surrounding dilated alveolar ducts, indicative of positive pressure ventilation effects, was noted. <bold>Conclusion:</bold> The underlying pathology for respiratory failure with severe COVID-19 was DAD. Therapy targeting fibrosis from an early stage, ventilatory management as a lung protective strategy, and introduction of ECMO if necessary are expected as a way to improve prognosis.