A 6-month-old infant develops post-intubation stridor after prolonged ventilation. Compared with an adult, the paediatric airway is disproportionately vulnerable to oedema at this level because it is the narrowest part of the infantile airway:

• A Glottis
• B Subglottis ✓
• C Supraglottis
• D Trachea at the thoracic inlet

Explanation

In adults the glottis is the narrowest point of the airway, but in infants the rigid cricoid ring makes the subglottis the narrowest segment. Because the cricoid is a complete cartilaginous ring, even 1 mm of mucosal oedema here reduces the cross-sectional area dramatically, producing biphasic stridor. This is why uncuffed or correctly sized tubes are used in small children and why subglottic stenosis follows prolonged intubation.

Reference: Scott-Brown's Essential Otorhinolaryngology, 2nd ed.

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Written and medically reviewed by the StethoPrep medical team.