LEMON Difficult Airway Predictor
LEMON difficult-airway assessment (Reed 2005): look externally, the 3-3-2 rule (one point per failed measurement), Mallampati >= III, obstruction/obesity, limited neck mobility.
Open the calculator → Runs in your browser. Data leaves only if you deliberately send a problem report from the interactive tool.
Example
- Look externally
- Yes
- 3-3-2: incisor opening < 3 fingerbreadths
- No
- 3-3-2: hyoid-mental distance < 3 fingerbreadths
- No
- 3-3-2: thyroid-to-floor-of-mouth < 2 fingerbreadths
- No
- Mallampati class >= III
- Yes
- Obstruction or obesity
- Yes
- Limited neck mobility
- No
Result: LEMON 3 of 7: 3 predictors of difficult intubation per Reed 2005 (higher = greater difficulty).
The tool opens with these values already filled in. Replace them with your own.
What the result means
- 0
- No predictors of difficult intubation per Reed 2005.
- 1-7
- Number of predictors of difficult intubation per Reed 2005; higher = greater difficulty.
What you enter
- Look externally: abnormal facial features (1)
- 3-3-2: incisor opening < 3 fingerbreadths (1)
- 3-3-2: hyoid-mental distance < 3 fingerbreadths (1)
- 3-3-2: thyroid-to-floor-of-mouth < 2 fingerbreadths (1)
- Mallampati class >= III (1)
- Obstruction or obesity (1)
- Limited neck mobility (1)
How this is calculated
Reed MJ, Dunn MJG, McKeown DW. Can an airway assessment score predict difficulty at intubation in the emergency department? Emerg Med J. 2005;22(2):99-102. Read the source ↗
A reference and educational tool. Not medical, legal, or financial advice, and not a substitute for clinician judgment.