The Application of a Mask in Patients With Severe Covid-19 Already Treated With High-flow Nasal Cannula.

Patients with severe hypoxemic respiratory failure due to Covid-19 are often treated with oxygen delivered through a high-flow nasal cannula (HFNC). This is according to guidelines. We have made the clinical observation that oxygenation sometimes improves when a mask (e.g. oxygen mask or inhalation mask) is applied on top of the HFNC. This has quickly become a clinical routine at intermediary care units at our hospital, where patients with HFNC are offered to test the intervention (mask + HFNC) as part of clinical routine. This study aims to evaluate this new routine in a standardised way.