Tracheal and Subglottic Stenosis Caused By Endotracheal Tubes
Endotracheal intubation is a skill learned by many specialties – anesthesia, emergency medicine, and critical care to name a few – which can have serious repercussions if not performed properly. Once the laryngoscope has been advanced, the hypopharyngeal landmarks identified (vocal cords, piriform sinuses, etc), and the endotracheal tube (ETT) passed through the cords, a small balloon is inflated flush against the walls of the trachea primarily to prevent air leaks (as well as protect against aspiration) during mechanical ventilation.
The problem is this pressure can actually cause varying levels of pressure-induced damage. The tracheal perfusion pressure (20-30 mmHg) can be compromised as the balloon cuff pressure increases leading to a situation where the tracheal mucosa is no longer perfused. This, in turn, leads to necrosis with subsequent scarring of the involved tissue; as with all scars, contraction of the granulation tissue occurs leading to narrowing of the lumen (i.e., tracheal stenosis).
In fact, trauma from ETT cuff over-distention and improper ETT sizing (being too large for the airway) are leading causes of tracheal stenosis and subglottic stenosis, respectively, from the same mechanism as above… but in different places along the airway.
It’s imperative that one actually looks at the patient to determine (a) the size of the ETT they really need and (b) only inflates the cuff just to the point of preventing an air leak, but avoids overinflation to minimize the risk of pressure-induced damage to the tracheal walls.