Preoperative difficult airway prediction using suprahyoid and infrahyoid ultrasonography derived measurements in anesthesiology.

Abstract

Airway management is one of the most important skills in everyday practice of anesthesia. Improper airway managementmight contribute to significant morbidity and mortality. In some patients, clinical parameters do not anticipate all difficultiesrelated to airway management. Ultrasonography (US) might confer a potential screening tool for difficult airway. Suprahyoidand infrahyoid US measurements have been investigated for difficult airway prediction in anesthesiology. The most extensivelyinvestigated parameter was the anterior neck soft tissue thickness measured at different levels: anterior to the hyoid bone,epiglottis and vocal cords commissure. Hyomental distances measured with the head placed in neutral, sniffing or maximalhyperextended position and the derived hyomental distance ratios have also been evaluated for difficult airway prediction. Forthe evaluation of the tongue, measurements such as thickness, cross-sectional area, width, volume and tongue-to-oral cavityratio can be used. Thus, anesthesiologists have many available potential US measurements, which could provide informationregarding airway anatomy during the preoperative airway assessment and could serve as potential screening parameters fordifficult airway. Still, we do not yet know which of these provides optimal predictive accuracy and larger sample size studiesare required to validate their use in the preoperative evaluation of the airway.