Safety and Efficacy of High Flow Nasal Canula in Patients With Mild Hypercapnia

Inclusion Criteria: * patients with mild Hypercapnia Exclusion Criteria: * Excluded cases had age less than 18 years or pediatric group . * patients with their mental state altered, confused, comatose, severe agitation or non cooperative * Cases with moderate or severe Hypercapnia * cases in need for immediate invasive mechanical ventilation * cases with respiratory rate more than 35 breath per minute. * cases with Respiratory exhaustion , fatigue , excess use of respiratory accessory muscles * Shock , hemodynamic instability, post arrest cases, * cases with facial trauma or severe nasal deformity, * Patients with sleep breathing disorders or upper airway obstruction * patients with history of home ventilation prior admission