Evaluate safety and efficacy of application ( high flow nasal canula) in cases with mild hypercapnia, included 30 patients who were hospitalized in Mansoura University chest department with mild Hypercapnia (Pco2 range 45-60 mmhg and power of hydrogen not less 7.30) of different pulmonary disease categories (Chronic obstructive pulmonary disease acute exacerbation, pneumonia, Interstitial lung diseases, etc).

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

study protocol