Inclusion Criteria:  ASA less than or equal II. The procedure expected to be completed within 2 hours.  Exclusion Criteria:  Patients with expected difficult airway management.  Hemodynamically unstable patients. Persistent cough or high airway secretions. Severe Emphysema or clinical signs of active infectious disease. Hypoxemia (PaO2 &lt;60 mmHg) or hypercarbia (PCO2 &gt;50 mmHg) Coagulopathy (INR &gt;1.5). Obesity (BMI &gt;30 Kg/m 2 ). Infection at the injection site, allergy to local anesthetics. Neurological disorders: seizures, intracranial mass or brain edema.