Canonical Question
Resp Anatomy
Master answer
Miller’s 5 Differences
| Newborn | Adult |
|---|---|
| Disproportionately large tongue that complicates laryngoscopy No dentition | Smaller tongue |
| Larynx is more cephaled (Cricoid at C4) | Larynx more caudal (Cricoid at C6) |
| Epiglottis is shaped differently (U shaped), being short, stubby, omega shaped, and angled over the laryngeal inlet | Epiglottis is longer and stiffer |
| Vocal cords are angled | |
| Larynx is funnel shaped, the narrowest portion occurring at the cricoid cartilage Oedema due to trauma may rapidly cause airway obstruction. |
Other Differences
| Airway | Narrower airways increase the resistance and work of breathing Airway more oedematous due to hormones from mother (oestrogen/progesterone) | Larger airways, less resistance and WOB |
| Nose | Obligate nose breathers Nasal obstruction may significantly impair respiration. | |
| Head | Proportionally enlarged head and occiput Optimal intubating position is neutral rather than ramped. | Head is relatively smaller |
| Neck | Less muscular and more mobile neck Proportionally short neck Favours airway obstruction when flexed. Less effective pharyngeal dilators | Decreased mobility and more likely to have arthritis and pathological issues More effective pharyngeal dilator muscles |
| Trachea | Intrathoracic trachea is also shorter May be only 4cm long, so there is little margin for error in tube placement. | |
| Bronchi | Angles of the bronchi take off is similar making left sided intubation as likely as right | Accidental intubation more likely to be right sided |
| Other differences | Increased physiological dead space due to large head 3.3 ml/kg | Decreased PDS 2 ml/kg |
JC / Gladwin 2020
Exam appearances
| Exam | Exact wording | Relationship | Success |
|---|---|---|---|
| 2009B Q07 | Compare and contrast the anatomy of the upper airway of a term newborn with that of an adult. | historical_member | — |