title: Airway sizes and proportions in children quantified by a video-bronchoscopic technique.
abstract: BACKGROUND
  A quantitative understanding of airway sizes and proportions and a reference point for comparisons are important to a pediatric bronchoscopist. The aims of this study were to measure large airway areas, and define proportions and factors that influence airway size in children.
  
  
  METHODS
  A validated videobronchoscope technique was used to measure in-vivo airway cross-sectional areas (cricoid, right (RMS) and left (LMS) main stem and major lobar bronchi) of 125 children. Airway proportions were calculated as ratios of airways to cricoid areas and to endotracheal tube (ETT) areas. Mann Whitney U, T-tests, and one-way ANOVA were used for comparisons and standard univariate and backwards, stepwise multivariate regression analyses were used to define factors that influence airway size.
  
  
  RESULTS
  Airways size increased progressively with increasing age but proportions remained constant. The LMS was 21% smaller than the RMS. Gender differences in airways' size were not significant in any age group or airway site. Cricoid area related best to body length (BL): cricoid area (mm2) = 26.782 + 0.254* BL (cm) while the RMS and LMS area related best to weight: RMS area (mm2) = 23.938 + 0.394*Wt (kg) and LMS area (mm2) = 20.055 + 0.263*Wt (kg) respectively. Airways to cricoid ratios were larger than airway to ETT ratios (p = 0.0001).
  
  
  CONCLUSIONS
  The large airways progressively increase in cross sectional area size, maintain constant proportional relationships to the cricoid and are gender independent across childhood. Anthropometric factors (body length and weight) are significantly related to but only have weakly predictive influences on major airway size. The cricoid is the most suitable comparator for other airway site measurements. These data provide for quantitative comparisons of airway lesions.
authors.affiliation: School of Medicine, University of Queensland, Herston 4029, Brisbane, Australia. brent_masters@health.qld.gov.au
authors.forename: Ian B
authors.initials: IB
authors.lastname: Masters
authors.forename: Robert S
authors.initials: RS
authors.lastname: Ware
authors.forename: Paul V
authors.initials: PV
authors.lastname: Zimmerman
authors.forename: Brian
authors.initials: B
authors.lastname: Lovell
authors.forename: Richard
authors.initials: R
authors.lastname: Wootton
authors.forename: Paul V
authors.initials: PV
authors.lastname: Francis
authors.forename: Anne B
authors.initials: AB
authors.lastname: Chang
mesh_terms: D001827:Body Height; D001835:Body Weight; D001980:Bronchi / Q000033:anatomy & histology* / Q000254:growth & development; D001999:Bronchoscopy; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D008297:Male; D012016:Reference Values; D014741:Video Recording