Subglottic stenosis is narrowing of the airway in the subglottic region — the area between the vocal cords and the inferior border of the cricoid cartilage. The cricoid cartilage is the only COMPLETE (360°) ring in the airway, making the subglottic region the narrowest fixed segment in the pediatric airway. In children, the subglottic diameter is approximately 4.5-5.5 mm at birth, meaning even 1 mm of edema reduces the cross-sectional area by approximately 35% and dramatically increases airway resistance (Poiseuille's law: resistance is inversely proportional to the FOURTH power of the radius). Acquired subglottic stenosis is most commonly caused by prolonged endotracheal intubation. The ETT sits at the level of the cricoid, and sustained tube pressure causes ischemic necrosis of the subglottic mucosa → granulation tissue formation → fibrosis → circumferential scar contracture → progressive airway narrowing. Risk factors for intubation-related stenosis include: oversized ETT (no air leak at <20-25 cmH₂O), prolonged intubation (>7-10 days in children), repeated intubations, traumatic intubation, gastroesophageal reflux (acid injury), and systemic infection. The Myer-Cotton grading system classifies severity: Grade I (0-50% obstruction — often...