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

Abstract

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.

High flow nasal oxygen therapy to avoid invasive mechanical ventilation in SARS-CoV-2 pneumonia: a retrospective study

“…In a prospective study, Montiel et al suggested that a surgical mask placed on patient’s face treated with HFNO improves oxygenation [ 22 ]. Our study was not designed to evaluate this effect or a potential association with a lower risk of IMV.…”

Effects of combined oxygen and surgical masks on inspired fraction of oxygen: relevance to COVID-19-induced respiratory failure

“…These findings could be explained by a decrease in room air entrainment diluting the gas mixture. 5 In contrast, Binks and colleagues 6 reported that F I O 2 , which was examined using a carbon dioxide sample line attached to a 16 G cannula, did not differ according to the position of the surgical mask relative to a Hudson oxygen mask at a flow rate of 6 L min −1 . However, the figure in their report showed significantly higher expiratory oxygen concentration when wearing an oxygen J o u r n a l P r e -p r o o f…”

Non-invasive respiratory support paths in hospitalized patients with COVID-19: proposal of an algorithm

“… 32 Early start: If PaO2:FiO2 < 300 or SpO2 < 93% on O2 > 5 L/min or SpO2 < 94% with FiO2 40% 33 Late start: SpO2 < 92% under O2 at 15 L/min and or PaFiO2 < 150 23 Start with: Ramp up from 30 L/min until 60 L/min to accustom the patient (40–50 if not tolerated); FiO2 to maintain spO2 > 93%; Temperature 31−37º according to patient’s comfort A surgical mask should be placed over the nose and mouth of a patient with a properly fitted nasal cannula before initiating therapy. It not only reduces droplet deposition 34 but also improves COVID-19 patient’s oxygenation 35 without any clinically relevant side effect, except for a moderate reduction in CO2 clearance. 34 This may require increasing flow rate of HFNC if the patient is displaying increased work of breathing.…”

“…A surgical mask should be placed over the nose and mouth of a patient with a properly fitted nasal cannula before initiating therapy. It not only reduces droplet deposition 34 but also improves COVID-19 patient’s oxygenation 35 without any clinically relevant side effect, except for a moderate reduction in CO2 clearance. 34 This may require increasing flow rate of HFNC if the patient is displaying increased work of breathing.…”