Subglottic Stenosis

Subglottic stenosis is a fixed narrowing between the vocal folds and the inferior border of the cricoid cartilage. The subglottis begins approximately 1 cm below the vocal folds and ends at the lower edge of the cricoid. The cricoid is the only complete cartilaginous ring in the airway. Unlike the more flexible tracheal rings, it cannot expand outward when swelling or scar develops inside it. Circumferential oedema or fibrosis therefore reduces the lumen directly. This is why the subglottis is the narrowest and most stenosis-prone portion of the paediatric airway. A child has very little reserve at this level. Normal subglottic diameter is approximately 4.5-5.5 mm in a full-term neonate and about 3.5 mm in a premature infant. Congenital stenosis is defined as a diameter under 4 mm in a full-term neonate or under 3 mm in a preterm infant. Adult reference diameters are roughly 11.6 mm in women and 15 mm in men. The most common acquired cause in both children and adults is prolonged or traumatic endotracheal intubation. When tube or cuff pressure exceeds the mucosal capillary perfusion...