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Updated: Oct 5, 2025

Point-of-Care Ultrasound: A Review of Ultrasound Parameters for Predicting Difficult Airways
Published on: April 7, 2023
Machine Learning Approaches for Predicting Difficult Airway and First-Pass Success in the Emergency Department:
Syunsuke Yamanaka1, Tadahiro Goto2, Koji Morikawa3
1Department of Emergency Medicine & General Internal Medicine, The University of Fukui, Fukui, Japan.
Background:
There is still room for improvement in the modified LEMON (look, evaluate, Mallampati, obstruction, neck mobility) criteria for difficult airway prediction and no prediction tool for first-pass success in the emergency department (ED).
Objective:
We applied modern machine learning approaches to predict difficult airways and first-pass success.
Methods:
In a multicenter prospective study that enrolled consecutive patients who underwent tracheal intubation in 13 EDs, we developed 7 machine learning models (eg, random forest model) using routinely collected data (eg, demographics, initial airway assessment). The outcomes were difficult airway and first-pass success. Model performance was evaluated using c-statistics, calibration slopes, and association measures (eg, sensitivity) in the test set (randomly selected 20% of the data). Their performance was compared with the modified LEMON criteria for difficult airway success and a logistic regression model for first-pass success.
Results:
Of 10,741 patients who underwent intubation, 543 patients (5.1%) had a difficult airway, and 7690 patients (71.6%) had first-pass success. In predicting a difficult airway, machine learning models-except for k-point nearest neighbor and multilayer perceptron-had higher discrimination ability than the modified LEMON criteria (all, P≤.001). For example, the ensemble method had the highest c-statistic (0.74 vs 0.62 with the modified LEMON criteria; P<.001). Machine learning models-except k-point nearest neighbor and random forest models-had higher discrimination ability for first-pass success. In particular, the ensemble model had the highest c-statistic (0.81 vs 0.76 with the reference regression; P<.001).
Conclusions:
Machine learning models demonstrated greater ability for predicting difficult airway and first-pass success in the ED.
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