Does the use of a diving mask adapted for non-invasive ventilation in hypoxemic acute respiratory failure in individuals with and without COVID-19 increase the ratio of arterial oxygen partial pressure to fractional inspired oxygen? A randomized clinical trial.

Non-invasive ventilation (NIV) can be used in acute hypoxemic respiratory failure (AHRF); however, verifying the best interface for its use needs to be evaluated in the COVID-19 pandemic scenario. The objective of this study was to evaluate the behavior of the ratio of arterial oxygen partial pressure to fractional inspired oxygen (PaO2/FiO2 ratio) in patients with AHRF with and without COVID-19 undergoing NIV with the conventional orofacial mask and the adapted diving mask. This is a randomized clinical trial in which patients were allocated into four groups: i) group 1: COVID-19 + adapted mask (n=12); ii) group 2: COVID-19 + conventional orofacial mask (n=12); iii) group 3: non-COVID-19 + adapted mask (n=2); iv) group 4: non-COVID-19 + conventional orofacial mask (n=12). The PaO2/FiO2 ratio was obtained 1, 24, and 48 hours after starting NIV, and the success of NIV was evaluated. This study followed the norms of the Consolidated Standards of Reporting Trials statement and was registered in the Brazilian Registry of Clinical Trials under registration RBR-7xmbgsz. Both the adapted diving mask and the conventional orofacial mask increased the PaO2/FiO2 ratio. The interfaces differed in terms of the PaO2/FiO2 ratio in the first hour [309.66 (11.48) and 275.71 (11.48), respectively] (p=0.042) and 48 hours [365.81 (16.85) and 308.79 (18.86), respectively] (p=0.021). NIV success was 91.7% in groups 1, 2, and 3, and 83.3% in group 4. No adverse effects related to interfaces or NIV were observed. NIV through the conventional orofacial mask interfaces and the adapted diving mask was effective in improving the PaO2/FiO2 ratio; however, the adapted mask presented a better PaO2/FiO2 ratio during use. There was no significant difference between interfaces regarding NIV failure.