[Clinical experience of high-flow nasal cannula oxygen therapy in severe COVID-19 patients].

Acute respiratory failure due to acute hypoxemia is the major manifestation in severe coronavirus disease 2019 (COVID-19). Rational and effective respiratory support is crucial in the management of COVID-19 patients. High-flow nasal cannula (HFNC) has been utilized widely due to its superiority over other non-invasive respiratory support techniques. To avoid HFNC failure and intubation delay, the key issues are proper patients, timely application and improving compliance. It should be noted that elder patients are vulnerable for failed HFNC. We applied HFNC for oxygen therapy in severe and critical ill COVID-19 patients and summarized the following experiences. Firstly, to select the proper size of nasal catheter, to locate it at suitable place, and to confirm the nose and the upper respiratory airway unobstructed. Secondly, an initial ow of 60 L/min and 37℃ should be given immediately for patients with obvious respiratory distress or weak cough ability; otherwise, low-level support should be given first and the level gradually increased. Thirdly, to avoid hypoxia or hypoxemia, the treatment goal of HFNC should be maintained the oxygen saturation (SpO