Surgical mask on top of high-flow nasal cannula improves oxygenation in critically ill COVID-19 patients with hypoxemic respiratory failure.

OBJECTIVE: Critically ill patients admitted in ICU because of COVID-19 infection display severe hypoxemic respiratory failure. The Surviving Sepsis Campaign recommends oxygenation through high-flow nasal cannula over non-invasive ventilation. The primary outcome of our study was to evaluate the effect of the addition of a surgical mask on a high-flow nasal cannula system on oxygenation parameters in hypoxemic COVID-19 patients admitted in ICU who do not require urgent intubation. The secondary outcomes were relevant changes in PaCO2 associated with clinical modifications and patient's feelings. DESIGN: We prospectively assessed 21 patients admitted in our mixed Intensive Care Unit of the Cliniques Universitaires Saint Luc. MAIN RESULTS: While FiO2 was unchanged, we demonstrate a significant increase of PaO2 (from 59 (± 6), to 79 mmHg (± 16), p < 0.001), PaO2/FiO2 from 83 (± 22), to 111 (± 38), p < 0.001) and SaO2 (from 91% (± 1.5), to 94% (± 1.6), p < 0.001), while the patients were under the surgical mask. The SpO2 returned to pre-treatment values when the surgical mask was removed confirming the effect of the device rather than a spontaneous positive evolution. CONCLUSION: A surgical mask placed on patient's face already treated by a High-flow nasal cannula device improves COVID-19 patient's oxygenation admitted in Intensive Care Unit for severe hypoxemic respiratory failure without any clinically relevant side