Which of the following devices is primarily used to maintain an open airway in unconscious patients?

The King LT airway is specifically designed to ensure that the airway remains open in unconscious patients. This device is a supraglottic airway, which means that it is positioned above the vocal cords, providing a clear passage for air to enter the trachea without the need for manipulation of the patient's head or neck. Its ease of insertion and ability to secure the airway make it particularly beneficial in emergency situations where quick intervention is required.

In contrast, other devices have different primary functions. An endotracheal tube, while effective for securing an airway, requires more skill and training for proper placement and is typically used in more controlled environments or for ventilating critically ill patients. A bag-valve mask is aimed at providing positive pressure ventilation, but it does not inherently maintain an open airway without adjuncts. The nasal cannula is suitable for delivering supplemental oxygen to conscious patients but is not designed to secure the airway in those who are unconscious.