Radiographic evaluation of endotracheal tube position.

A malpositioned endotracheal tube is a potential hazard to the intubated patient. Ideally, the tube tip should be 5+/-2 cm from the carina when the head and neck are in neutral position. In 92 of 100 patients studied, the carina overlay T5, T6, or T7 on portable radiographs. Therefore, even when the carina is not visible, it can be assumed that a tube tip positioned at the level of T3 or T4 is safe. The degree of neck flexion or extension at the time of radiography may be determined by evaluating the position of the mandible relative to the vertebral bodies.