A Retrospective Observational Study of Utility of Nonrebreathing Mask in Moderate to Severe Hypoxemic COVID-19 Pneumonia
Authors: Dash Trinath , Tipparapu Karthik , Singh Sarvendra Vikram , Roy Koustav 
Published: May 2022

ABSTRACT

Introduction:
The pulmonary manifestations of covid-19 disease may range from mild pneumonia to severe acute respiratory distress syndrome (ARDS) complicated by shock or multiorgan failure. Proper selection and utilization of oxygen delivery system is the key factor in treating the hypoxemic respiratory failure in severe covid-19 disease. Here by, we present a retrospective observational study of utility of NRBM (Non Rebreathing Mask) in 1876 moderate to severe hypoxemic Covid-19 pneumonia patients in a single centre and its outcome.

Objectives:
To study the utility of NRBM in moderate to severe hypoxemic COVID-19 pneumonia Patients.

Material and Methods:
This was a single centre retrospective observational study. Out of 5024 microbiologically confirmed (by Rapid antigen test/RTPCR/TRUENAT) covid-19 pneumonia patients admitted since September, 2020 to May 2021,1876 patients of age >14 years admitted in the department of Respiratory medicine with moderate to severe hypoxemia (SpO2 <90%) and respiratory rate <30/min who were provided supplemental oxygen by NRBM with or without associated Co-morbidities were included in the study. These patients were provided oxygen Supplementation by NRBM according to their SpO2 levels (<90 %) by starting with a minimum flow rate of 10 L/ min to maximum of 15 L/min.

Results:
Out of 5024 microbiologically confirmed covid-19 patients who were admitted in respiratory ICU and ward,1876 patients were provided supplemental oxygen by NRBM. Patients were distributed according to their duration of onset of symptoms, mode of oxygen delivery, number of days of supplemental oxygen and number of patients expired accordingly and results were observed and analyzed. Majority of the patients belongs to the age group 45 to 60 yrs. The average duration of presentation to ER with worsened symptoms for oxygen requirement was 6.4 days from the onset of symptoms. 1703 (90.77%) patients recovered well without any further deterioration with NRBM. The average duration of days for weaning from NRBM to simple face mask or nasal prongs were 4.5 days based on their respective SpO2 >90% (corresponds to Pao2 >60 mmhg), respiratory rate (<16/min) and heart rate <100 bpm. About 9.3% of the patients (173) who were provided NRBM support who further deteriorated or showed poor response even after maximum period of 7 days were provided with NIV support (130 patients i.e. 6.92%), HFNC support (14 patients i.e. 0.74%) and invasive mechanical ventilation (29 patients i.e. 1.54%).66 patients who were initially provided NRBM support, recovered and 107 patients (2.129%) succumbed to their illness. smoking (table-4)has been observed to be the major risk factor in majority of the patients (43.7%). As per the data of this study there is significant correlation between the utilization of NRBM and advanced age, early initiation of NRBM rather than directly initiating NIV/HFNC/Invasive mechanical ventilation and duration of presentation to the hospital with symptoms. Smokers were observed to be associated with more severe presentation and longer time for weaning. Hypertension and Diabetes were observed to most commonly associated comorbidities in the study population. Hypoxemic covid-19 patients who were provided NRBM support were having better outcome and reduced mortality risk compared to patients who were provided NIV/HFNC/Invasive mechanical ventilation.

Conclusion:
In reference to the results in our study, we recommend the use of NRBM in moderate to severe hypoxemic patients of covid-19 disease at the early course of the disease.