title: Use of sonography for airway assessment: an observational study.
abstract: OBJECTIVE
  The purpose of this study was to evaluate the feasibility of sonography in identifying the anatomic structures of the upper airway and to describe their appearance on sonography.
  
  
  METHODS
  We enrolled 24 healthy volunteers, placed them supine with their head extended and neck flexed (the "sniffing" position), and performed a systematic sonographic examination of their upper airway from the floor of the mouth to the suprasternal notch.
  
  
  RESULTS
  We were able to visualize all relevant anatomic structures in all of the participants using either a linear or curved transducer oriented in 1 of 3 planes: sagittal, parasagittal, and transverse. Bony structures (eg, the mandible and hyoid) were brightly hyperechoic with an underlying hypoechoic acoustic shadow. Cartilaginous structures (eg, the epiglottis, thyroid cartilage, cricoid cartilage, and tracheal rings) were hypoechoic, and their intraluminal surface was outlined by a bright air-mucosa interface. The vocal cords were readily visualized through the thyroid cartilage. However, the posterior pharynx, posterior commissure, and posterior wall of the trachea could not be visualized because of artifacts created by an intraluminal air column.
  
  
  CONCLUSIONS
  Sonography of the upper airway is capable of providing detailed anatomic information and has numerous potential clinical applications.
authors.affiliation: Departments ofAnesthesia, University Health Network, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Mandeep
authors.initials: M
authors.lastname: Singh
authors.forename: Ki Jinn
authors.initials: KJ
authors.lastname: Chin
authors.forename: Vincent W S
authors.initials: VW
authors.lastname: Chan
authors.forename: David T
authors.initials: DT
authors.lastname: Wong
authors.forename: Govindarajulu A
authors.initials: GA
authors.lastname: Prasad
authors.forename: Eugene
authors.initials: E
authors.lastname: Yu
mesh_terms: D005260:Female; D006801:Humans; D007830:Larynx / Q000000981:diagnostic imaging*; D008297:Male; D009055:Mouth / Q000000981:diagnostic imaging*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014132:Trachea / Q000000981:diagnostic imaging*; D014463:Ultrasonography / Q000379:methods*; D055815:Young Adult