Can the Modified LEMON Score Predict Difficult Intubation?

Daniel J. Pallin, MD, MPH reviewing Hagiwara Y et al. Am J Emerg Med 2015 Jun 19.
A Japanese registry study suggests the score has fair sensitivity and specificity.

The LEMON score is a mnemonic for predicting difficult intubation. It stands for Look, Evaluate the 3-3-2 rule, Mallampati score, Obstruction, and Neck mobility (NEJM JW Emerg Med Mar 2005 and Emerg Med J 2005; 22:99). Using a prospective registry of emergency department intubations in Japan, researchers assessed the sensitivity and specificity of the modified LEMON criteria for predicting difficult intubation (defined as requiring >1 attempt). The modified LEMON criteria do not include assessment of the Mallampati score or measurement of thyroid-to-mouth distance (part of the 3-3-2 rule).

Of 4034 intubations, 84% were performed with a direct laryngoscope and, of these, 5.4% were difficult (required more than 1 attempt). Among the direct laryngoscope group, sensitivity of any unfavorable finding during a modified LEMON assessment was 86%, specificity was 48%, and negative predictive value was 98%. Among the 16% of intubations performed with a video laryngoscope, 7.4% were difficult. Sensitivity was 95%, specificity 40%, and negative predictive value 99%.

Citation(s):

Hagiwara Y et al. Prospective validation of the modified LEMON criteria to predict difficult intubation in the ED. Am J Emerg Med 2015 Jun 19; [e-pub].