The current study aimed to investigate the use of the modified LEMON (which stands for Look externally, Evaluate the 3–3-2 rule, Obstructed airway, and Neck mobility) criteria in predicting difficult intubation in pediatric patients in the emergency department (ED).

An observational multicenter analysis of data from the 4th Japanese Emergency Airway Network (JEAN-4) study was conducted from October 2018 to September 2022. Patients aged <18 years who were intubated and registered in the JEAN-4 study were included in this analysis. The primary outcomes were the sensitivity, specificity, positive predictive value, and negative predictive value of the modified LEMON criteria for predicting difficult tracheal intubation (defined as ≥3 intubation attempts by pediatric emergency attending physicians or fellows).

In total, 546 patients were included in this study. There were 34 (6 %) and 512 (94 %) cases of difficult tracheal intubation and nondifficult tracheal intubation. The sensitivity, specificity, positive predictive value, and negative predictive value of the modified LEMON criteria for predicting difficult tracheal intubation in the ED were 41 % (95 % confidence interval [CI]: 25 %–59 %), 73 % (95 % CI: 69 %–77 %), 9 % (95 % CI: 5 %–15 %), and 95 % (95 % CI: 92 %–97 %), respectively.

Based on this multicenter observational study, the modified LEMON criteria presented with neither a high sensitivity nor specificity for predicting difficult intubation in pediatric patients in the ED. Therefore, with consideration of age and physical characteristics, standards individualized based on the specific needs of pediatric patients must be developed.