In predicting difficult airway, the LEMON score is used. A patient with a Mallampati score of III, thyromental distance of 5 cm, inter-incisor gap of 3 cm, and no neck mobility restriction has which LEMON components contributing to difficulty?
- A Look externally (facial hair) and Mallampati III only
- B Obstruction and Neck mobility only
- C No significant airway predictors present
- D Mallampati III and Evaluation (3-3-2 rule fails on thyromental distance) ✓
Explanation
The LEMON assessment: L=Look externally, E=Evaluate 3-3-2 rule (inter-incisor ≥3 finger-breadths, hyoid to chin ≥3 finger-breadths, hyoid to thyroid notch ≥2 finger-breadths), M=Mallampati, O=Obstruction, N=Neck mobility. A thyromental distance of 5 cm is borderline (normal ≥6.5 cm or ≥3 finger-breadths), which violates the 3-3-2 rule component. Mallampati III predicts difficult laryngoscopy. Together, these two positive LEMON components significantly increase predicted difficult airway probability. Inter-incisor gap of 3 cm (≈2 finger-breadths) is borderline — normal is ≥4 cm.
Reference: Morgan & Mikhail's Clinical Anesthesiology, 6th ed.
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Written and medically reviewed by the StethoPrep medical team.