Analysis of the functionally-narrowest portion of the pediatric upper airway in sedated children

Abstract

The narrowest portions of the pediatric larynx are the glottis and subglottic region. However, the pliable and paralyzed subglottic region, acting like a curtain, is no resistance when passing an endotracheal tube. Therefore, the ‘functionally’ portion of the pediatric upper airway, which may be the most vulnerable to damage during intubation, is the unyielding portion below the cricoid cartilage. We investigated the functionally-narrowest portion below the cricoid cartilage.Computed tomography (CT) was performed under deep sedation. CT images were used for measurement of dimensions and cross-sectional area (CSA) of the larynx at the level of the cricoid, subcricoid, and trachea. We analyzed the anteriorposterior (AP) diameter, transverse diameter, and CSA below the cricoid cartilage (at the cricoid, subcricoid, and tracheal levels).CT images of 46 children from 8 months to 96 months were reviewed from electric medical record (EMR). The mean ± SD of AP diameter was the shortest at the subcricoid level (cricoid, 105.7 ± 15.8 mm; subcricoid, 94.6 ± 15.3 mm; and trachea, 101.5 ± 15.7 mm; P < .001). The mean ± SD of transverse diameter was the shortest at the trachea level (cricoid, 99.8 ± 12.2 mm; subcricoid, 102.5 ± 13.7 mm; and trachea, 98.8 ± 10.7 mm; P = .01). The mean ± SD of CSA was the smallest at the subcricoid level (cricoid, 8781.5 ± 1963.3 mm2; subcricoid, 8425.0 ± 2025.7 mm2; and trachea, 8523.7 ± 1791.1 mm2; P = .02). The AP diameter at the subcricoid level was narrower than the transverse diameter at trachea level (mean difference: 4.2 mm, 95% confidence interval [CI]: 0.7–7.7, P = .02).Since the most susceptible portion for airway damage is unyielding portion, our findings suggest that, functionally, the narrowest portion of the pediatric larynx is located in the subcricoid region.

Ultrasonography measurement of glottic transverse diameter and subglottic diameter to predict endotracheal tube size in children: a prospective cohort study

“…Since there is evidence that the subglottic transverse diameter is less than the anterior to posterior (A-P) diameter 16,17 , we measured the subglottic transverse diameter, which we believed to be the narrowest part of the child's airway and consistent with other studies [6][7][8][9] . The correlations between the subglottic diameter and outer diameter of ETT in our study were moderate whereas other studies recruiting children aged ≤ 6 years found a strong correlation between the subglottic diameter and outer diameter 6,8,18 .…”

Revisiting the Morphometry of Cricoid Cartilage and Vocal Folds

“…Diabetic retinopathy (DR) is one of the most feared complications of diabetes. Several researches have been done to estimate the prevalence of DR (6)(7)(8)(9). Blindness caused by DM currently affects approximately 15 Introduction Larynx is an air passage, phonation organ and acting as a sphincter.…”

“…Since the morphometric properties of the larynx alter significantly in childhood period of the life, recent studies focused on properties of pediatric larynx. (6)(7)(8). These studies described the narrowest parts of the pediatric larynx helping the surgeons during surgical procedures such as endotracheal intubation.…”