The cuff of an endotracheal tube is an essential piece of modern anesthesia. It serves as a seal of the airway—decreasing the likelihood of aspirating pharyngeal secretions into the trachea and lungs (debatable) and allowing adequate positive-pressure ventilation. It also serves to anchor the ETT in place, thus allowing position changes during surgery with less risk of mainstem intubation or inadvertent extubation. Traditionally, we learn in anesthesiology that the cuff pressures of the ETT should be within the range of 20 to 30 cm H₂O. Although these numbers are very strict in pediatric anesthesia (and a component of every pediatric anesthesiology text), cuff pressure in adults is of key importance as well.

The pediatric airway differs in many ways from that of an adult. One of the key differences is the location of the narrowest portion of the airway. Remember that the adult airway is cylindrical-shaped, with the tightest area being between the vocal cords or glottis. However, in neonates, infants, and young children, the airway is more funnel-shaped and becomes tightest at the level just below the glottic aperture (the subglottis). Because the pediatric subglottic region can be very narrow, anesthesiologists often do not use cuffed ETTs unless the patient is around age 8 to 10 years or older. In many circumstances, without a cuff, the diameter of the ETT itself may often be too wide for the airway, even when it passes easily beyond the cords. It is not uncommon in pediatric cases that the anesthesiologist changes to a smaller ETT for this reason. Above 30 cm H₂O, the pressure exerted by the tube on the subglottis for a prolonged operation may cause mucosal ischemia,
resulting in sloughing of the mucosal lining and potentially resulting in subglottic stenosis or worse.