Q: How far cuff of endotracheal tube should be placed to prevent vocal cord palsy?


Answer:  At least 15 mm below the vocal cords

Vocal cord palsy is an undesired, though rare  but a serious complication of endotracheal intubation. The anterior branch of recurrent laryngeal nerve traverses between the lamina of thyroid cartilage and laryngeal mucosa. Overinflated cuff of ET-Tube may compress to cause vocal cord paralysis. First 10 mm of the area below vocal cord is most sensitive for damage. Ideally, ET-tube cuff should be at least at 15 mm below the vocal cords.



Reference: 

Benumof JL, Saidman J, editors. 2nd ed. London: Mosby; 1999. Anesthesia and Perioperative Complications; p. 9.