Abstract
BackgroundA 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.MethodsA 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.ResultsAirways 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).ConclusionThe 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.
Highlights
A quantitative understanding of airway sizes and proportions and a reference point for comparisons are important to a pediatric bronchoscopist
The median age of the overall group was 2.05 (0.13–9.80) years and there were no significant differences between the median ages of males 1.91 (0.13–9.25) years and females 2.51 (0.18–9.80) years (p = 0.30) or within any age grouping with p values = 0.59, 0.66 and 0.19 for the 3 age groups I, II and III respectively
The all groups mean ± SD left main stem bronchus (LMS) area of 23.77 ± 8.66 mm2 was significantly smaller than the right main stem bronchus (RMS) of 29.95 ± 8.99 mm2 (p = 0.001)
Summary
A quantitative understanding of airway sizes and proportions and a reference point for comparisons are important to a pediatric bronchoscopist. The semi-quantitative photogrammetric techniques that have been published regarding these disorders [2,3] are limited by a number of factors [4], and at best, have tended to underestimate the change being measured. Some of these limitations have been overcome by our new quantitative technique for measurement of airway lumen: the colour histogram mode technique [5]. As bronchoscopic techniques evolve roles in research of areas such as wheezy infants and even endobronchial challenge testing [6], the ability and capacity to measure luminal changes and an understanding of airway proportions and an appropriate comparator site for measurements becomes essential
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