Hypoxemia is a frequent and potentially fatal complication occurring in patients during gastrointestinal endoscopy. The administration of propofol sedation increases the risk of most complications, especially hypoxemia. Nevertheless, propofol has been increasingly used in the United States, and the trend is likely to increase in the years to come. Patient satisfaction and endoscopist satisfaction along with rapid turnover are some of the touted reasons for this trend. However, propofol sedation generally implies deep sedation or general anesthesia. As a result, hypopnea and apnea frequently occur. Inadequate sedation and presence of irritable airway often cause coughing and laryngospasm, both leading to hypoxemia and potential cardiac arrest. Hence, prevention of hypoxemia is of paramount importance. Traditionally, standard nasal cannula is used to administer supplement oxygen. However, it cannot sufficiently provide continuous positive airway pressure (CPAP) or positive pressure ventilation. Device manufacturers have stepped in to fill this void and created many types of cannulas that provide apneic insufflation of oxygen and CPAP and eliminate dead space. Such measures decrease the incidence of hypoxemia. This review aimed to provide essential information of some of these devices. Clin Endosc 2021 Mar 18.