Paediatric airway anatomy, equipment sizing, and ETT selection

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Target exams

Red flags

• The infant desaturates rapidly after apnoea: a reduced functional residual capacity and an oxygen consumption around twice the adult value (approximately 6 mL/kg/min) make the safe apnoea time short. Preoxygenation is essential.
• The paediatric larynx is high and anterior (infant C3 to C4, adult C5 to C6), the tongue is large relative to the oral cavity, and the epiglottis is long, floppy and U-shaped. A straight (Miller) blade and a different laryngoscopy technique are often required.
• The cricoid cartilage is classically the narrowest point of the paediatric airway (not the vocal cords), giving the airway a funnel shape; an uncuffed tube that passes the cords can still obstruct at the cricoid.
• Laryngospasm is the canonical cause of paediatric perioperative cardiac arrest from airway events: it escalates from partial obstruction to complete closure, bradycardia, and arrest within minutes if unrecognised.
• A concurrent upper respiratory tract infection multiplies the risk of laryngospasm (odds ratio about 2), and an airway anomaly multiplies it further (odds ratio about 3.4).