To compare the outcomes of HFNC and HVNI in COVID-19 patients with acute respiratory failure as regard need for mechanical ventilation, changes of arterial blood gases (ABG) parameters, duration of ventilatory support and delay between admission and intubation

novel clinical syndrome caused by a previously unknown coronavirus, SARS-Cov-2, was first identified in Wuhan (China) in December 2019. Despite massive efforts to contain viral transmission, a worldwide epidemic has developed from this virus. This disease is presently known as COVID-19 COVID-19 pandemic reached over 45 million confirmed infections and claimed the lives of more than 1.2 million people worldwide. The clinical features of COVID-19 are diverse and range from asymptomatic to critical illness and death. Severe and critical cases represented 14% and 5% of laboratory-confirmed COVID-19 patients and need ICU admission Several non-invasive options exist to support COVID-19 patients with mild or moderate respiratory distress and may reduce the numbers of patients requiring intubation, mechanical ventilation in some severely ill patients such as High flow nasal oxygen (HFNO) High flow nasal oxygen (HFNO) includes high flow nasal cannula and high velocity nasal insufflation. High flow oxygen systems provide oxygen-rich heated humidified gas to the patient's nose at flow levels sufficient to deliver a constant, precisely set high FiO2. Exhalation is to the open air. HFNO reduces dead space, provides low levels of PEEP, and decreases breathing frequency and work of breathing HFNC flow rates reach up to 60 L/min, whereas HVNI delivers flow rates up to 40 L/min due to differing mechanisms of delivery (4).

High velocity nasal insufflation (HVNI) utilizes a small-bore nasal cannula to generate higher velocities of gas delivery than HFNC which uses large bore cannula

Inclusion Criteria:

• COVID-19 positive by RT-PCR
• Age≥ 18 years
• Both gender
• Classical radiological lesions of COVID-19 on HRCT chest.
• Respiratory rate > 30/ min and not responding to non-rebreather masks.
• COVID-related pneumonia requiring non-invasive ventilatory support (high-flow nasal cannula, and / or non-invasive ventilation and / or CPAP)

Exclusion Criteria:

• Age < 18 years
• Patients who refuse to participate in the study
• Severe respiratory failure requiring invasive ventilatory support
• Indication of immediate tracheal intubation
• Significant acute progressive circulatory insufficiency
• Impaired conscious level
• Nasal blockade