HFNC Versus Conventional Oxygen Therapy in Prolonged Upper Gastrointestinal Endoscopy in the ICU

Inclusion Criteria: * Both males and females with age 20-60 years * American Society of Anesthesiologists (ASA) class I, II or III * Patients will undergo UGI endoscopic procedure with anticipated procedure time of over 15 minutes because of complexity of the procedure or recurrence, as assessed by the consultant gastroenterologist responsible for the case Exclusion Criteria: * Patient refusal or propofol allergy history. * Suspected difficult airway or Mallampati score more than 3 * Body mass index (BMI) more than 35 kg/m2 (weight will be measured in kilograms and height in meters,then BMI will be measured by equation where: BMI=weight(Kg) / height square (m2)) * Pregnant patients * Respiratory compromise as patients dependent on supplemental oxygen including respiratory failure or with active chest condition e.g. bronchial asthma or pneumonia * Cardiovascular compromise including heart failure and shocked patients * Severe uncontrolled hematemesis with shocked or risk of aspiration. * Patients deemed as high risk of SRAEs by the anesthesiologist, anticipated requirement or plan for general anesthesia involving airway instrumentation including a laryngeal mask or tracheal intubation.