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The primary objective of the prospective study is to compare the incidence, duration, and severity of oxygen desaturation in high-risk patients randomized to nasal mask with nasal positive airway pressure (PAP) or standard care (nasal cannula) receiving propofol sedation during colonoscopy in an ambulatory surgical center (ASC).

Patients will be randomized in groups of ten to one of two groups using a random number table.

Group A: standard care with a nasal cannula. Group B: SuperNO2VA™EtCO2. Following the procedure subjects will be asked to complete satisfaction surveys before leaving the ASC and 48 +/- hours following their procedure.

Researchers will compare levels of satisfaction and levels of oxygen saturation.

This study involves the oxygenation, continuous positive airway pressure, and ventilation of a subject via nasal mask and oxygenation via a closed facemask. The interventions directly related to this study are that of supplement oxygen, bag-mask ventilation, and continuous nasal CPAP intra-operatively and in the recovery unit.

Patients will be randomized in groups of ten to one of two groups using a random number table.

Group A: standard care with a nasal cannula. Group B: SuperNO2VA™EtCO2. For each anesthetic case, a preoperative history and physical and intraoperative record will be documented.

Once in the endoscopy suite, the patients will have baseline vital signs, EtCO2 and oxygen levels measured. Continuous monitoring of heart rate, end tidal CO2 (EtC02), O2 saturation, and every 3-minutes BP monitoring will be obtained. For patients randomized to group A, the anesthesia provider will supply oxygen via nasal cannula at 10LPM. For patients randomized to group B, the anesthesia provider will attach the SuperNO2VA™ EtCO2's circuit port to the hyperinflation bag with the oxygen flow rate to 10 L/min, and the adjustable pressure-limiting (APL) valve completely closed. Initial propofol bolus of 0.5-1.0 mg/kg actual body weight will be administered for sedation. No other sedative or analgesic will be permitted besides propofol. MOAA/S scores will be assessed by the anesthesiologist and medical team and recorded by the research assistant. If the patient's MOAA/S score is ≥ 4, additional 20-50 mg boluses will be administered every 30 - 90 seconds until a MOAA/S score <4 is reached. Once a MOAA/S <4 is reached the endoscopist will insert the colonoscope into the rectum. Sedation will be titrated to maintain a MOAA/S <4 throughout the procedure. If the patient's MOAA/S score ≥4, additional 20-50 mg boluses of propofol will be administered every 30-90 seconds until the MOAA/S is <4. The measurements recorded during colonoscopy for both groups will be: time of administration of sedation; incidence, severity, and duration of oxygen desaturation; number, duration and reason for performing the airway maneuver(s); duration of the procedure; total dose of medication; blood pressure, heart and respiratory rate, and oxygen saturation; time to full recovery; and patient cooperation. The research assistant will document their patient's depth of sedation, cooperation with procedure, and safety.

Endoscope techniques performed during the procedure such as biopsies, dilation, polypectomy, etc. will be tracked. Techniques to facilitate proximal passage of the endoscope such as moving the patient or abdominal pressure will also be noted. If the anatomic extent desired to complete the colonoscopy is not reached (i.e., colon stricture, excessive looping of the instrument), then the patient will be withdrawn from the study.

Patients will recover in the endoscopy suite. The patients will have continuous monitoring of heart rate, end tidal CO2 (EtC02), O2 saturation, and every 5-minute BP monitoring and MOAAS Score. Once a MOAAS score of 5 is obtained, the patient will be offered to drink independently unless deemed inappropriate by the treating physician(s). The endoscopist when available will discuss findings with the patient and/or family, the patient will then dress and leave the endoscopy suite when possible. The time to discharge will be obtained for each patient. Patients will also complete a satisfaction and pain questionnaire before discharge. Subjects will be sent surveys to complete at 48 hours post discharge, concerning their satisfaction and their subjective degree of impairment due to the sedation. They will have the option to complete this electronically via a link to REDCap or with a self-addressed envelope and paper form of the survey. If the patients do not complete or send back their questionnaire, someone will contact them by telephone to collect the data. A statistician using student T-test, Fishers exact test, and other statistical methods they deem appropriate will analyze the collected data.

Inclusion Criteria:

1. Age ≥18 years
2. Outpatients undergoing colonoscopy.
3. American Society of Anesthesiology (ASA) Physical Status I-III
4. BMI ≥35 kg/m2, documented obstructive sleep apnea or BMI>30 with STOP-BANG score ≥3
5. Written informed consent

Exclusion Criteria:

1. Inpatient status
2. Active Congestive Heart Failure Exacerbation
3. Untreated ischemic heart disease
4. Acute exacerbation of respiratory disorders, including COPD and asthma
5. Emergent procedures
6. Pregnancy
7. Previous enrollment in this study
8. Inability to provide informed consent.
9. Additional medical testing planned for the same day.
10. History of allergic reaction to propofol
11. History of allergic reaction to polypropylene or PVC.
12. Tracheostomy
13. Supra-glottic or sub-glottic tumor
14. Gastrointestinal tract obstruction or delayed transit (including delayed gastric emptying, gastric bezoar, achalasia, toxic megacolon).
15. Known obstructing colon tumor, lesion, or stricture
16. Previous colon surgery (excluding anal surgery)
17. Active GI bleeding (hematochezia or melena during procedure preparation)
18. Large polyp (> 2cm) removal
19. Previous failed or unsuccessfully completed colonoscopy.