Inclusion Criteria:  Adult population of both sex (ASA I, II). Between18-65 years of age. Patients for the upper airway. Patients need intubation/invasive mechanical ventilation.  Exclusion Criteria:  ASA >II Advanced Respiratory disease. Advanced cardiovascular disease. Smokers. Pregnancy. Recent upper airway trauma. Age less than 18 years or more than 65 years. Patients BMI of more than 35 Refuse to sign the consent.