Mandibular length for prediction of difficult laryngoscopies: a prospective cohort

Abstract

Purpose: Predicting difficult airways still remains challenging and advances are needed in this field. For this purpose, mandibular anatomy has shown to be valuable as some features like prognathism and retrognathism are related to difficult airways. As prognathism and retrognathism are associated with mandibular length, we aimed to evaluate whether the mandibular length would also be associated with difficult laryngoscopies. Methods: We performed a prospective cohort with 125 patients undergoing general anesthesia for surgical procedures. We collected preoperatively data on age, sex, weight, height, body mass index, modified Mallampati test (MMT), and mandibular length (ML). The main outcome was the grade of glottic view according to Cormack and Lehane's classification system: easy (grades 1 or 2) or difficult laryngoscopy (grades 3 or 4). Bivariate analyses were undertaken and predictive models built with their ROC curves and AUC. Results: Difficult laryngoscopy was presented by 9 patients (7.2%) and was associated with sex (p=0.009), MMT (p=0.020), and ML (p=0.002). The AUC for MMT was 68.9% (95% CI: 59-78.7%) and for ML was 88.9% (95% CI:77.7-100%). Conclusions: Mandibular length is associated with difficult laryngoscopies and seems to be more accurate than the modified Mallampati test for prediction of difficult airways.