Endoscopic retrograde cholangiopancreatography (ERCP) is an imaging procedure that visualizes the drainage ducts of the pancreas, gallbladder, and liver through the use of a duodenoscope and contrast media. By endoscopically identifying the ampulla of Vater, the common bile duct is cannulated. ERCP is also frequently utilized for therapeutic interventions, such as endoscopic sphincterotomy, bile duct stone extraction, stent placement in malignant and benign biliary strictures, and biopsy collection, thus playing a critical role in both the diagnosis and treatment of pancreatobiliary disorders.

ERCP, being more invasive than routine upper endoscopies or colonoscopies, typically necessitates deeper levels of sedation. The procedure is performed in the prone, modified prone, or lateral decubitus position, which increases the risk of hypoxemia and hypoventilation due to upper airway obstruction. Furthermore, endoscopic instruments inserted through the oral cavity limit anesthesiologists' access to the patient's airway, thereby restricting ventilation support during gastrointestinal endoscopy. Ensuring airway stability during sedation is paramount for patient safety and procedural efficacy. Currently, a range of devices, including traditional nasal cannulas, high-flow oxygen masks, and procedural oxygen masks, are employed to provide oxygen support throughout the procedure.

The existing literature includes randomized controlled trials and systematic reviews aimed at preventing hypoxemia during ERCP. Through this study, investigators aim to make a novel contribution to the literature by assessing the effectiveness of a recently introduced procedural oxygen mask.

This study aims to compare the efficacy of two oxygen delivery methods-High-Flow Nasal Cannula (HFNC) and Procedural Oxygen Mask (POM)-in preventing hypoxemia during Endoscopic Retrograde Cholangiopancreatography (ERCP). Designed as a randomized, parallel-group, prospective study, participants were assigned to two groups, Group H (HFNC) and Group P (POM), in a 1:1 ratio using computer-assisted random allocation. However, due to the visible differences between the oxygen delivery devices, neither healthcare providers nor patients could be blinded to the randomization.

The study was planned to include 134 patients (67 per group) with a 95% confidence level (1-α) and 90% test power (1-β). To account for an anticipated 10% dropout rate, the total sample size was set at 150 patients.

Throughout the ERCP procedure, all patients will be monitored using pulse oximetry, electrocardiography (ECG), and non-invasive blood pressure monitoring. Capnography will be applied in both groups, and necessary interventions will be carried out by anesthesia specialists if a patient's oxygen saturation falls below 90%. All interventions and events will be meticulously documented. Following the procedure, patients will be monitored in the post-anesthesia care unit (PACU), and those with a Modifiye Alderete score of 10 will be discharged.

The FiO2 will be maintained constant throughout the procedure. Patients will initially receive midazolam at a dose of 0.02 mg/kg, followed by 0.5 mg/kg of ketamine. To ensure adequate sedation, propofol will be administered as an initial bolus dose of 0.5-1.0 mg/kg, with additional boluses of 0.25-0.5 mg/kg every 1-3 minutes as needed to maintain the target sedation level.

The target sedation depth will be 3-4 on the Ramsay Sedation Scale (RSS), and this level will be maintained throughout the procedure. Upon completion, patients will be awakened using verbal and tactile stimuli. Once their RSS reaches 2, they will be transferred to the Post-Anesthesia Care Unit (PACU). Patients will be discharged from the PACU upon achieving a Modified Aldrete Score (MAS) of 10.

Vital signs, procedure durations, and dosages of medications used for each patient will be meticulously recorded. All anesthesia-related decisions during the procedure will be made by the supervising anesthesia specialist.

Inclusion Criteria:

• Aged 18-75 years
• American Society of Anesthesiologists (ASA) classification of 1-2-3
• Patients scheduled for ERCP at Kocaeli City Hospital Endoscopy Unit

Exclusion Criteria:

• Refused to participate in the study
• Had an allergy to ketamine, propofol, or midazolam
• Had a BMI >30 kg/m²
• Were pregnant or in the postpartum period
• Had a STOP-BANG score ≥3
• Had a history of intubation within the past 3 months
• Had a history of lower respiratory tract infection within the past 3 months
• Had a history of intensive care unit (ICU) admission within the past 3 months
• Had a tracheostomy or a history of tracheostomy placement
• Were oxygen-dependent
• Had lung cancer or a history of lung surgery
• Had asthma, COPD, or interstitial lung disease

The data will not be shared