When assessing for a difficult airway what does the LEMON acronym remind us to check?

In a study, only three factors from LEMON are associated with a difficult intubation, which are they?


  • L=Look externally (facial trauma, large incisors, beard or moustache, and large tongue)
  • E=Evaluate the 3-3-2 rule (incisor distance <3 fingerbreadths, hyoid/mental distance <3 fingerbreadths, thyroid-to- floor of mouth distance <2 fingerbreadths)
  • M=Mallampati (Mallampati score ≥3)
  • O=Obstruction (presence of any condition that could cause an obstructed airway)
  • N=Neck mobility (limited neck mobility).


Actually relevant to difficult intubation:

1) large incisors

2) inter-incisor distance <3 fingerbreadths

3) thyroid-to-floor-of-mouth distance <2 fingerbreadths


Reed MJ et al. Can an airway assessment score predict difficulty at intubation in the emergency department? Emerg Med J 2005 Feb; 22:99-102.