What device stimulates a gag reflex in a conscious patient and can result in vomiting?

The device that stimulates a gag reflex in a conscious patient and can result in vomiting is the oropharyngeal airway. This device is designed to maintain an open airway by preventing the tongue from obstructing the throat. When inserted in a conscious individual, particularly one who is not fully unconscious or is partially aware, the oropharyngeal airway can trigger the gag reflex. This reflex is a protective mechanism of the body, and in some cases, it can lead to vomiting as a reaction to the stimulation.

In contrast, the other devices mentioned do not function in the same way. A nasal cannula is primarily used for delivering supplemental oxygen and does not stimulate the gag reflex. A tracheostomy tube is used for direct access to the airway through a surgical opening in the trachea, typically in patients who need long-term ventilation, and it is less likely to provoke a gag response. A non-rebreather mask is also designed for oxygen delivery and covers the mouth and nose, but it does not stimulate the gag reflex like an oropharyngeal airway does.