High-flow nasal oxygen therapy (HFNO) is an innovative high-flow system that allows for delivering up to 60 liters/ min of heated and fully humidified gas with a fraction of inspired oxygen (FIO2) ranging between 21% and 100% . High-flow nasal oxygen therapy has become an increasingly popular choice of therapy due to the potential complications of invasive ventilation and the frequent uncomfortable or life-threatening adverse effects that are produced in non-invasive ventilation (NIV) . The HFNO allows the modification of only two variables: the percentage of oxygen being delivered and the rate of gas flow . Numerous well-designed studies have been conducted into the use of the HFNC in the treatment of critically ill patients, and HFNC is now widely used in the treatment of patients with various diagnoses including acute hypoxemic respiratory failure or acute respiratory distress syndrome (ARDS) , and is used in post-extubation treatment, post-cardiothoracic surgery respiratory distress , and respiratory compromise induced by heart failure .

High-velocity nasal insufflation (HVNI) is a form of HFNC that utilizes a small bore nasal cannula to generate higher velocities of gas delivery than its counterparts using large bore HFNC. HVNI can accomplish a complete purge of extrathoracic dead space and may be able to provide ventilatory support in patients with acute hypercapnic respiratory failure in addition to oxygenation support.

This study is necessary because, even though studies were being conducted to determine both the optimal technique for HFNO delivery and the clinical setting in which it is most useful, the best strategy for weaning from HVNI remains unknown. It has also not been established at what point a patient should be considered stable enough to attempt for withdrawing the HVNI

High-flow nasal oxygen therapy (HFNO) is an innovative high-flow system that allows for delivering up to 60 liters/ min of heated and fully humidified gas with a fraction of inspired oxygen (FIO2) ranging between 21% and 100% . High-flow nasal oxygen therapy has become an increasingly popular choice of therapy due to the potential complications of invasive ventilation and the frequent uncomfortable or life-threatening adverse effects that are produced in non-invasive ventilation (NIV) . The HFNO allows the modification of only two variables: the percentage of oxygen being delivered and the rate of gas flow . Numerous well-designed studies have been conducted into the use of the HFNC in the treatment of critically ill patients, and HFNC is now widely used in the treatment of patients with various diagnoses including acute hypoxemic respiratory failure or acute respiratory distress syndrome (ARDS) , and is used in post-extubation treatment , post-cardiothoracic surgery respiratory distress , and respiratory compromise induced by heart failure.

High-velocity nasal insufflation (HVNI) is a form of HFNC that utilizes a small bore nasal cannula to generate higher velocities of gas delivery than its counterparts using large bore HFNC. HVNI can accomplish a complete purge of extrathoracic dead space and may be able to provide ventilatory support in patients with acute hypercapnic respiratory failure in addition to oxygenation support .

This study is necessary because, even though studies were being conducted to determine both the optimal technique for HFNO delivery and the clinical setting in which it is most useful, the best strategy for weaning from HVNI remains unknown. It has also not been established at what point a patient should be considered stable enough to attempt to start withdrawing the HVNI

Inclusion Criteria:

• This study will include Patients over 18 years receiving respiratory support through HVNI for acute hypoxemic respiratory failure
• Those eligible for weaning according to European Respiratory Society weaning criteria

Exclusion Criteria:

I. Extensive facial trauma or burn II. Refusal to participate. III. Usual long-term treatment with NIV for chronic disease IV. Tracheotomy or other upper airway disorders