The aim of the current study is to compare the incidence of oxygen desaturation in patients receiving HFNC at different flow rates compared to conventional oxygen therapy via a simple cannula during ERCP. Secondary outcomes include lowest average observed oxygen saturation (SpO2), snoring classification scores and satisfaction levels of both patients and gastroenterologists.

Participants will be randomized to 3 groups: G0 will receive a 5 l/ min flow rate through a nasal cannula at and FiO2 of 40 %, G1 will receive a 15 l/ min flow rate and FiO2 of 40% and G2: will receive a 60L/min flow rate and FiO2 of 40%.

High flow nasal cannula provides adequate oxygenation in patients with compromised pulmonary function. Very few studies in the literature addressed its use with IV sedation in the OR. Successful application of High Flow nasal cannula in intravenous deep sedation cases in the OR will benefit in the reduction of airway manipulation and side effects from general anesthesia.

The aim of the current study is to compare the incidence of oxygen desaturation in patients receiving HFNC at different flow rates compared to conventional oxygen therapy via a simple cannula during ERCP. Secondary outcomes include lowest average observed oxygen saturation (SpO2), snoring classification scores and satisfaction levels of both patients and gastroenterologists.

A total of 60 patients undergoing ERCP will be equally randomized to 3 groups:

G0: will receive a 5 l/ min flow rate through a nasal cannula at and FiO2 of 40 %, G1: will receive a 15 l/ min flow rate and FiO2 of 40% and G2: will receive a 60L/min flow rate and FiO2 of 40%.

The three groups' intra-procedure and outcome parameters and variables will be compared. Statistical comparison will be made using the ANOVA, Student's t-test, and Chi-squared test. Level of statistical significance will be considered at p<0.05. ANOVA test will be performed to compare the different means between the four groups. Minimum and maximum 3 of 17 values will be recorded for each value in all 3 groups. A two sided P value of less than 0.05 will be considered statistically significant.

Inclusion Criteria:

1. Patient able to give consent.
2. Patient undergoing deep sedation.
3. Patient undergoing ERCP procedure with no restrictions on the duration of the procedure.
4. Age > 18 years
5. Patients with BMI < 40 kg/m2

Exclusion Criteria:

1. Patient unable to give consent
2. Patient refusal to participate
3. Patients undergoing general anesthesia
4. age less than 18 years old
5. Patients with severe heart failure (EF<30%)
6. Morbidly obese Patients with BMI > 40 kg/m2
7. Patients with sleep apnea
8. Claustrophobia
9. Risk of aspiration due to severe reflux
10. Facial injury, facial malformation
11. Nasal defects/obstruction
12. ASA 4 patients