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Prediction of difficult laryngoscopy in school-aged patients with microtia.

BACKGROUND
Children with microtia may experience difficult laryngoscopy because the ear and the mandible develop from the first and second bronchial arches and clefts.


METHODS
In this prospective observational study, we enrolled 166 patients (6-14 years old) with microtia scheduled for auricular reconstruction with autologous costal cartilage framework. Airway of the subjects was assessed preoperatively with the Modified Mallampati classification, Thyromental distance, Interincisor gap, Forward protrusion of the mandible and Horizontal length of the mandible. Anesthesiologist performed the direct laryngoscopy. Difficult laryngoscopy was classified as grade III or IV based on the Cormack-Lehane classification.


RESULTS
A total of 166 patients completed the study, including 158 (95%) isolated microtia patients and 8 (5%) hemifacial microsomia patients. The incidence of difficult laryngoscopy was 34/166 (20.5%) in all patients, 3/8 (37.5%) in hemifacial microsomia patients, 31/158 (19.6%) in isolated microtia patients (P=0.35). Multivariate logistic regression shows that Thyromental distance, Interincisor gap, Forward protrusion of the mandible are all independent predictors of difficult laryngoscopy. The sensitivity and specificity of each predictor were: Thyromental distance (82.35%, 89.39%), Interincisor gap (58.82%, 86.36%), and Forward protrusion (17.65%, 97.73%), respectively. The cutoff values of Thyromental distance and Interincisor gap for prediction of difficult laryngoscopy were 4.0cm and 3.3cm. The best combination of predictors was Thyromental distance/Interincisor gap/Forward protrusion of the mandible with a sensitivity of 94.12% and specificity of 86.36%.


CONCLUSIONS
The combination of Thyromental distance, Interincisor gap, and Forward protrusion of the mandible is the optimal assessment to predict difficult laryngoscopy in school-aged patients with microtia.