title: Upper airway in infants-a computed tomography-based analysis.
abstract: BACKGROUND
  Recent studies suggest that the pediatric airway is elliptical with the subglottis rather than the cricoid as the narrowest part contrary to the old belief of a funnel-shaped airway. The shape of the airway in neonates and infants has not been studied separately. This study seeks to define the shape of the upper airway in neonates and infants, and determine if there are differences in airway shape between infants and older children.
  
  
  METHODS
  We studied 40 computed tomographic scans of children from birth to 12 months of age undergoing radiological evaluation unrelated to airway symptomatology. The computed tomographic scans were obtained during either natural sleep or with sedation and spontaneous ventilation without airway devices in place. Transverse and anteroposterior diameters were measured at the subglottic level and at the cricoid ring.
  
  
  RESULTS
  The mean age was 5.9 ± 3.4 months. The mean transverse and anteroposterior diameters were 5.3 ± 0.83 mm and 7.2 ± 0.89 mm at the subglottic region and 6.1 ± 0.86 mm and 6.7 ± 0.79 mm at the cricoid level. An increase in the transverse dimension of the airway was observed from the subglottic region to the cricoid ring. Although the anteroposterior dimension decreased from the subglottis to the cricoid ring, the airway remained wider in the anteroposterior dimension compared to the transverse dimension from the subglottis to the cricoid ring.
  
  
  CONCLUSIONS
  The present study demonstrates that the airway in neonates and infants between the subglottic area and the cricoid remains elliptical. The cricoid is not round as has been observed in older children. The airway is wider anteroposteriorly and narrows in the transverse dimension from the subglottis to the cricoid in infants.
authors.affiliation: Department of Anesthesiology and Pain Medicine, Nationwide Children's Hospital, Columbus, OH, USA.|Department of Anesthesia, King Fahad Medical City, Riyadh, Saudi Arabia.
authors.forename: Tariq M
authors.identifier: http://orcid.org/0000-0003-0631-3959
authors.initials: TM
authors.lastname: Wani
authors.affiliation: Department of Anesthesia, Royal Glamorgan Hospital, NHS Wales, Llantrisant, UK.
authors.forename: Mahmood
authors.initials: M
authors.lastname: Rafiq
authors.affiliation: Department of Anesthesia, King Fahad Medical City, Riyadh, Saudi Arabia.
authors.forename: Nahida
authors.initials: N
authors.lastname: Akhter
authors.affiliation: Department of Anesthesia, King Fahad Medical City, Riyadh, Saudi Arabia.
authors.forename: Faris Saeed
authors.initials: FS
authors.lastname: AlGhamdi
authors.affiliation: Department of Anesthesiology and Pain Medicine, Nationwide Children's Hospital, Columbus, OH, USA.
authors.forename: Joseph D
authors.initials: JD
authors.lastname: Tobias
mesh_terms: D000367:Age Factors; D000375:Aging / Q000502:physiology; D015331:Cohort Studies; D003413:Cricoid Cartilage / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D005260:Female; D005931:Glottis / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D009333:Neck / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D014057:Tomography, X-Ray Computed; D014132:Trachea / Q000033:anatomy & histology* / Q000000981:diagnostic imaging*
keywords: computed tomography; cricoid; larynx; pediatric airway; sevoflurane; trachea; vocal cords