Computed tomography for difficult airways diagnostics

Abstract

The objective was to determine the effectiveness of computed tomography for difficult laryngoscopy diagnosis.Materials and methods. We examined 60 patients who underwent preoperative computed tomography of the head and neck and assessed the risk of difficult airways using the LEMON scale. The following CT signs were studied: the thickness of the tongue and soft tissues at the level of the vocal folds, the vertical distance from the highest point of the hyoid bone to the body of the mandible, the thickness of the epiglottis, the length of the epiglottis, the location of the vocal folds at the level of the cervical vertebrae, the atlanto-occipital gap, the gap between the first and the second cervical vertebrae, the distance between the vocal folds. After induction of anesthesia, patients were divided into 2 groups depending on the results of laryngoscopy according to the Cormack–Lehane classification. The diagnostic ability of the clinical features of the LEMON scale and CT findings was calculated using ROC-AUC analysis in patients in the difficult and normal airway groups.Results. The analysis of the obtained data showed that the LEMON scale has an average diagnostic ability (AUC 0.697 p ≤ 0.023 CI–0.534–0.860); the sensitivity of the method was 26.7%, specificity – 95.6%, compared with CT diagnostics. The most effective CT-predictor is the thickness of the tongue (sensitivity – 80%, specificity – 77.8%), to a lesser extent – the vertical distance from the highest point of the hyoid bone to the mandible and the thickness of the epiglottis (sensitivity 73%, 60% and specificity 66.7% , 62.4%, respectively).Conclusion. The use of computed tomography is effective in identifying predictors of difficult laryngoscopy. Radiation methods for diagnosing difficult laryngoscopy are more sensitive compared to the LEMON scale. The diagnostic criteria for difficult laryngoscopy are thickness of the tongue – 75.75 mm, vertical distance from the highest point of the hyoid bone to the mandible – 20.85 mm, and thickness of the epiglottis – 2.65 mm.

Keywords

• difficult airways
• diagnostics
• computed tomography
• safety
• maintenance of airway patency
• tracheal intubation