Variations in Upper Airway Anatomy

Understand the differences encountered in the upper airway for neonates, children and adults.

Neonates and Children

Changes are most obvious below 1 year of age. They typically resolve by ~8 years of age.

• Head and neck changes
  • Obligate nose breathers
    Nasal obstruction may significantly impair respiration.
  • Proportionally enlarged head and occiput
    Optimal intubating position is neutral rather than ramped.
  • Proportionally short neck
    Favours airway obstruction when flexed.
• Laryngeal changes
  • Disproportionately large tongue that complicates laryngoscopy
  • Epiglottis is u-shaped, longer, and stiffer
  • Larynx lies at C4 (rather than C6 in adults)
  • Narrowest part of the upper airway is the transverse diameter of the vocal cords
    Not at the cricoid.
• Intrathoracic changes
  • Intrathoracic trachea is also shorter
    May be only 4cm long, so there is little margin for error in tube placement.
  • Left and right bronchi arise at similar angles, so endobronchial intubation may occur on either side
  • Airways themselves are narrower, and have a higher resistance to flow.

References

1. Nickson, C. Paediatric Airway. LITFL.
2. Anderson, C. Anatomy of the Respiratory system.. ICU Primary Prep.
3. Chambers D, Huang C, Matthews G. Basic Physiology for Anaesthetists. Cambridge University Press. 2015.
4. Tobias JD. Pediatric airway anatomy may not be what we thought: implications for clinical practice and the use of cuffed endotracheal tubes. Paediatr Anaesth. 2015 Jan;25(1):9-19.