Systems on Top of Nasal Cannula Improve Oxygen Delivery in Patients with COVID-19: a Randomized Controlled Trial

Abstract

BACKGROUND: Treating hypoxemia while meeting the soaring demands of oxygen can be a challenge during the COVID-19 pandemic. OBJECTIVE: To determine the efficacy of the surgical facemask and the double-trunk mask on top of the lowflow oxygen nasal cannula on arterial partial pressure of oxygen (PaO 2 ) in hypoxemic COVID-19 patients. DESIGN: Randomized controlled trial. PARTICIPANTS: Hospitalized adults with COVID-19 and hypoxemia treated with the low-flow nasal cannula were enrolled between November 13, 2020, and March 05, 2021. INTERVENTIONS: Patients were randomized in a 1:1:1 ratio to receive either the nasal cannula alone (control) or the nasal cannula covered by the surgical facemask or the double-trunk mask. Arterial blood gases were collected at baseline and 30 min after the use of each system. The oxygen output was adapted afterwards to retrieve the baseline pulse oxygen saturation. The final oxygen output value was recorded after another 30-min period. MAIN MEASURES: The primary outcome was the absolute change in PaO 2 . Secondary outcomes included changes in oxygen output, arterial partial pressure of carbon dioxide (PaCO 2 ), vital parameters, and breathlessness. KEY RESULTS: Arterial blood samples were successfully collected in 24/27 (8 per group) randomized patients. Compared to the nasal cannula alone, PaO 2 increased with the surgical facemask (mean change: 20 mmHg, 95% CI: 0.7-38.8; P = .04) and with the double-trunk mask (mean change: 40 mmHg; 95% CI: 21-59; P < .001). Oxygen output was reduced when adding the surgical facemask (median reduction: 1.5 L/min [95% CI: 0.5-4.5], P < .001) or the double-trunk mask (median reduction: 3.3 L/min [95% CI: 2-5], P < .001). The double-trunk mask was associated with a PaCO 2 increase of 2.4 mmHg ([95% CI: 0-4.7], P = .049). Neither mask influenced vital parameters or breathlessness.CONCLUSIONS: The addition of the surgical facemask or the double-trunk mask above the nasal cannula improves arterial oxygenation and reduces oxygen consumption.

Oxygen supplementation above a low-flow nasal cannula in patients with COVID-19 may improve arterial oxygen levels but not breathlessness

“…Poncin et al 1 found that compared with the NC alone, addition of the surgical face mask or the DTM above the NC improved patient arterial oxygenation. The vital parameters as well as the degree of breathlessness, however, did not differ among the groups.…”

“…All patients with hypoxaemia requiring low-flow oxygen therapy between 3 and 7 L/min with an NC to maintain peripheral capillary oxygen saturation (SpO2) between 92% and 96% were randomised in a 1:1:1 ratio to receive oxygen therapy via three different methods. Either an NC alone (control) or the NC covered by the surgical face mask or the DTM was used to deliver oxygen 1…”

“…A need to improve oxygen delivery with easy-to-perform procedures mandated the introduction of double-trunk masks (DTM), where two tubes are fixed in each of the side holes. Poncin and colleagues investigated the effects of a surgical face mask or a DTM above the NC on arterial blood parameters in hypoxaemic patients with COVID-19 1…”