[Application of surgical mask with high-flow nasal cannula (HFNC) leads to improved oxygenation in patients with COVID-19: a set of case reports].

The new coronavirus SARS-CoV-2 is responsible for the development of acute infectious illness named COVID-19. While most people have a mild course of the disease, a significant minority of patients will develop some degree of respiratory insufficiency requiring hospitalization. In case of failure of conventional oxygen therapy, the method of choice in patients with respiratory insufficiency is ventilation with high-flow nasal cannula (HFNC). In order to reduce the dispersion of infectious aerosol during HFNC treatment, nasal cannula is often covered with a surgical mask in many hospitals. According to recent observations, the application of a surgical mask in these patients could also have a positive effect on oxygenation parameters without clinically relevant side effects. In the present set of case reports, we demonstrate this effective, simple and affordable way how to improve oxygenation in patients with COVID-19 and hypoxemic respiratory failure treated with HFNC.