Predictive factors of cricoid ring size in adults in relation to acquired subglottic stenosis.

Subglottic stenosis secondary to endotracheal intubation is a distinct clinical entity. Prolonged intubation is an important causative factor, but even short-term endotracheal intubation with too large a tube can damage the cricoid sufficient to cause delayed subglottic stenosis. After studying cricoid size and other factors in 130 adult laryngectomy and autopsy specimens, the following conclusions were reached: (1) The subglottic cricoid is the smallest, fixed cross section in the upper airway. (2) Even if height is comparable, women have smaller cricoid diameters than men. (3) Height is the best predictor of cricoid size. (4) Weight and race are not accurate predictors. (5) Third finger length and cricoid size correlate well, particularly in men. (6) Thus height and third finger length can be used to choose the proper endotracheal tube for adults.