###### Abstract  
The need for mechanical ventilation is one of the main concerns related to the care of patients with COVID-19. The aim of this study is to evaluate the efficacy of a bubble device for oxygen supplementation. This device was implemented for the selected patients hospitalized with severe COVID-19 pneumonia with persistent low oxygen saturation. Patients were selected in three major COVID-19 hospitals of Baha state in Brazil from July to November 2020, where they remained with the device for seven days and were monitored for different factors, such as vital signs, oximetry evaluation, and arterial blood gasometry. Among the 51 patients included in the study, 68.63% successfully overcame hypoxemia without the necessity to be transferred to mechanical ventilation, whereas 31.37% required tracheal intubation (_p_ value \(<\) 0.05). There was no difference of note on the analysis of the clinical data, chemistry, and hematological evaluation, with the exception of the SpO\({}_{2}\) on follow-up days. Multivariate analysis revealed that the independent variable, male sex, SpO\({}_{2}\), and non-inhaled mask, was associated with the necessity of requiring early mechanical ventilation. We concluded that this bubble device should be a prior step to be utilized before indication of mechanical ventilation in patients with persistent hypoxemia of severe COVID-19 pneumonia. S 2022 2022 10 June 202  
number of total deaths because of the large number of cases, resulting until the beginning of May 2022 in an additional 6.23 million deaths worldwide since the first case reported in December 2019 [6; 7]. Brazil is the third country in the number of confirmed cases of the disease, being the second in the number of deaths, which resulted in an overload of the health system due to the lack of beds inside the intensive care units (ICU) in different Brazilian states [7; 8; 9]. The clinical manifestations of individuals diagnosed with COVID-19 can vary between asymptomatic and those with critical disease development through severe symptoms [10; 11]. It is widely demonstrated that the pathophysiology of the disease is quite complex and may affect organs such as the brain, liver, kidney, heart, coagulation system, and especially the lungs [12; 13]. Thus, symptoms associated with COVID-19 range from fever, dry cough, diarrhea, myalgia, or fatigue to severe complications normally related to the respiratory system, such as viral pneumonia and acute respiratory distress syndrome [14]. Furthermore, it has been shown that the elderly and people of any age who have underlying medical conditions have had the worst disease prognosis through the development of a severe clinical condition [15; 16]. The severe or critical manifestation of COVID-19 has been reported in 14% and 5% of patients, respectively [17]. Even so, despite most diagnosed patients presenting mild or medium symptoms (81%), the appearance of severe disease symptoms has been one of the main concerns of medical teams, because its development is associated with an increase in the fatality rate [18; 19]. In addition, studies indicate that patients who present the most severe symptoms of the disease have impaired lung functions even after infection with SARS-CoV-2 [20; 21]. Patients hospitalized with COVID-19 commonly present with hypoxia (PaO\({}_{2}<\)60 mmHg) and are then treated symptomatically along with oxygen therapy, usually through non-invasive ventilation (NIV) [22; 23]. In these cases, mechanical ventilation or invasive ventilation (IV) may become necessary when patients progress towards respiratory failure, making assistance necessarily provided within the ICUs through tracheal intubation [24]. Within this context, the mortality rate among patients with these conditions can vary between 20 and >90%, making it the most critical moment in the care of patients with COVID-19 [25; 26].