Predictors of Success of High Flow Nasal Therapy in Covid 19 Patients

Coronavirus disease 2019 (COVID-19) is a potentially fatal infection caused by the novel severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2)[1]. The highly contagious nature and exponential spread of SARS-CoV-2, coupled with its potential for a rapid progressto acute respiratory distress syndrome (ARDS), has overwhelmed health care systems globally, contributing to the high mortality rates in early reports [1,2].

The initial approach for respiratory support for severe COVID-19 pneumonia centredaround invasive mechanical ventilation and the standard lung protective strategy recommended for ARDS[3]. This may have been detrimental to a proportion of patients due to ventilator induced lung injury (VILI) and associated systemic inflammation[4]. Furthermore, other strategies to improve oxygenation may be more appropriate in patients with hypoxemic respiratory failure who do not require ventilatorysupport[4].

High-flow nasal oxygen (HFNO) is delivered by an air/oxygen blender, an active humidifier, a single heated circuit, and a nasal interface.

It delivers adequately heated and humidified medical gas at flow-rates of up to 60L/min, and is considered to have a number of physiological benefits, including the reduction of anatomical dead space and work of breathing, the provision of a constant fraction of inspired oxygen with adequate humidification and a degree of positive end-expiratory pressure (PEEP) [5,6].