What is the radiographic appearance of an endotracheal tube, and where is it optimally placed?
An ETT usually appears as a faintly radiopaque tube with a thin, densely radiopaque line along its length, and its position should be determined relative to the carina, which if not seen on a chest radiograph can be approximated by following the course of the mainstem bronchi medially at the T5-T7 level. In adults, the tip of an ETT should be below the thoracic inlet and approximately 5 to 7 cm above the carina when the patient’s head is in neutral position, as flexion or extension of the neck can cause the tube to move either 2 cm higher or lower, respectively. The optimal width of the tube should be one half to two thirds of the tracheal width (generally <3 cm), and the inflated cuff should not distend the trachea because tracheal injury may occur.
