title: Tracheobronchial anatomy and the distribution of inhaled foreign bodies in children.
abstract: BACKGROUND
  Foreign body inhalation is a common and life-threatening emergency, and is most prevalent in young children. The traditional view is that tracheobronchial anatomy determines that an inhaled foreign body is more likely to enter the right main bronchus. This view has been challenged in young children, in whom the distribution of inhaled objects is more evenly distributed between the bronchi. We, therefore, investigated tracheobronchial anatomy relevant to foreign body inhalation in children.
  
  
  METHODS
  One hundred and fifty-six normal pediatric chest radiographs were selected from a large electronic database. Eight groups of radiographs were identified: supine (n=76) and erect; males (n=84) and females; aged <3 years (median age 12 [0.5-29] months) and > or =3 years (median age 126 [48-180] months). Tracheobronchial widths and angles were determined using a standardized technique with good reproducibility.
  
  
  RESULTS
  Overall, children had a proximal right main bronchus that was consistently steeper and slightly wider than the left (P<0.001), becoming more vertical in the erect position (P=0.0001). In most children, the carina was positioned to the left of the mid-trachea, but in 34% of cases (40% of infants), it was to the right of the mid-trachea. The effects of age and gender were otherwise minimal.
  
  
  CONCLUSIONS
  On the basis of tracheobronchial anatomy, an inhaled foreign body is more likely to enter the right bronchial tree than the left in children of all ages. However, the variability in the position of the carina with respect to the mid-trachea may explain why this right-sided preference is less marked in children compared to adults.
authors.affiliation: Department of Clinical Radiology, St. James's University Hospital, Leeds, UK.
authors.forename: Nasim
authors.initials: N
authors.lastname: Tahir
authors.forename: William H
authors.initials: WH
authors.lastname: Ramsden
authors.forename: Mark D
authors.initials: MD
authors.lastname: Stringer
mesh_terms: D000293:Adolescent; D000367:Age Factors; D001980:Bronchi / Q000033:anatomy & histology*; D001995:Bronchography; D002648:Child; D002675:Child, Preschool; D005260:Female; D005547:Foreign Bodies / Q000000981:diagnostic imaging*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D009929:Organ Size; D053120:Respiratory Aspiration / Q000000981:diagnostic imaging*; D014132:Trachea / Q000033:anatomy & histology* / Q000000981:diagnostic imaging