[Role of ultrasound in airway management].

Recent advancement in ultrasound technology allows us to visualize detailed structures around the airway. One of the important roles of the airway ultrasound is to identify cricothyroid membrane where the emergent invasive access should be performed. Now we can assess the risk of difficult cricothyroidotomy before anesthesia of which the new ASA difficult airway guideline suggests. Airway ultrasound can also be used to confirm correct position of the tracheal tube and laryngeal mask, difficult laryngoscopy prediction in obese patients, assessing vocal cord function, prediction of the post extubation stridor, and so on. We also introduce perioperative evaluation of the airway via sonography (PEAS) protocol in this review.