Endoscopic retrograde cholangiopancreatography (ERCP) is a technique for evaluating the bile duct, pancreatic duct, and ampulla. Hypoxia is the most common cardiopulmonary complication during ERCP, with a reported rate of 16.2 to 39.2%. The key to preventing hypoxia is to ensure the sufficient oxygenation and ventilation of patients during these procedures. The commonly used approaches to treat hypoxia with a non-instrumented airway are increasing the oxygen flow and lifting the jaw, applying with both hands, displacing the jaw upwards and anteriorly, which allowed the upper airway to remain open. We hypothesized that the supraglottic oxygen delivery via an endotracheal tube can reduce the incidence of hypoxia in patients under deep sedation during ERCP.