Introduction: Difficult intubation is defined as the need for three or more attempts for intubation of the trachea or more than 10 minutes to complete, situation occurs in 1.5% to 8% of the general anesthesia procedures. Objective: In this study a comparison of the assessment of airway ultrasound specifically insonando hyoid bone for display or not, compared to the degree of Cormack-Lehane in adult patients undergoing general anesthesia was performed. Material and methods: This study is a prospective, observational cross where 69 patients scheduled for elective surgery under general anesthesia were evaluated. They were subjected to a detailed evaluation of the airway prior to your surgery. Mallampati Classification, Distance and Distance Esternomentoniana thyromental documented, was also evaluated with submental ultrasound visualization or not of the hyoid bone. At the time of surgery, after general anesthesia monitoring and direct laryngoscopy was performed and the degree of Cormack-Lehane was observed. Results: The incidence of difficult intubation was 2.9%. Finally, the ultrasound to visualize the hyoid bone had a sensitivity of 96.4% on; specificity 75.0%, positive predictive value of 81.8%; negative predictive value of 92.7% which supports us to suggest as a predictor of the difficult airway. Conclusions: Display hyoid bone via the submental ultrasound demonstrated higher sensitivity than the combination of standard clinical scales. The highest sensitivity and negative predictive value were shown to display or not the hyoid bone and correlated with a difficult laryngoscopy.
