A new method for objective identification and measurement of airway lumen in paediatric flexible videobronchoscopy

Elucidating the anatomy of the quadrivial pattern of the right upper lobe bronchus using 3D-CT images

Background

A preoperative understanding of the thoracic anatomy of the patients with the quadrivial pattern of branching of the right upper lobe is key to successful surgery. We analyzed the quadrivial pattern of division of the right upper lobe bronchus of patients using three-dimensional (3D) computed tomography (CT) angiography and bronchography.

Methods

A total of 212 consecutive adult patients who had undergone thoracic CT scans before surgery at the Zhujiang Hospital of the Southern Medical University from August 2020 to August 2021 was used for retrospective study. The 3D-CT images were taken using Mimics software. Radiology technicians processed all the 3D images, and thoracic surgeons confirmed the validity of all the reconstructions.

Results

Six (2.83%) were identified as having a quadrivial pattern of division of the right upper lobe bronchus with 1 female, and 5 males. Based on the number of pulmonary artery branches, 5 (83.3%) and 1 (16.7%) were classified as “trunk superior (Tr.sup) + ascending artery (A.asc) and Tr.sup + trunk inferior (Tr.inf) + ascending artery (A.asc) (1/6, 16.7%). Based on the number of ascending artery branches, the patients were also divided into type A (3/6, 50%) and type B (3/6, 50%). The patients were also divided into 1 of the following three types based on the origins of the A2: (I) A2 originates from A6 (1/6, 16.7%); (II) A2 originates from the pulmonary trunk (4/6, 66.7%); and (III) A2a originates from A3, and A2b originates from the pulmonary artery stem (1/6, 16.7%). According to the number of A1b branches, patients were divided into two types: (I) 1 branch (4/6, 66.7 %); and (II) 2 branches (2/6, 33.3 %). In the present study, anterior + central type was observed which classified into two types: (I) type Iab, the anterior vein ran from V1a to V1b (4/6, 66.7%); and (II) type Ib, the anterior vein ran from V1b only (2/6, 33.3%).

Conclusions

3D-CT was successfully used for analyzing the quadrivial bronchovascular patterns of the right upper lobe bronchus. Our study provides certain references to perform anatomical pulmonary segmentectomy, which should improve the success rate of operations.

Differences in Flexible and Rigid Bronchoscopy for Assessment of Tracheomalacia

OBJECTIVES/HYPOTHESIS

Both flexible and rigid bronchoscopy can be used to assess tracheomalacia; however, there is limited evidence comparing the two techniques. The objective of this study was to compare flexible and rigid bronchoscopy for evaluating the location and severity of tracheomalacia in children.

STUDY DESIGN

Retrospective case series.

METHODS

This was a retrospective study of children with both flexible and rigid bronchoscopy under the same sedation. All bronchoscopies were reviewed by three bronchoscopists for the location and severity of tracheomalacia. The location of collapse was defined as upper, middle, or lower trachea, and the severity of collapse was defined as none (0%-25% collapse), mild/moderate (26%-75% collapse), and severe (>75% collapse).

RESULTS

Twenty-one patients were recruited for this study with a variety of neonatal respiratory diseases. There was 94% agreement (κ = 0.64) for assessment of tracheomalacia in the upper trachea. However, agreement was only 75% (κ = 0.50) in the middle trachea and 76% (κ = 0.52) in the lower trachea. In the subset of patients without tracheostomy, agreement improved to 100%, 88%, and 82% for the upper, middle, and lower trachea, respectively. There was poor correlation for tracheomalacia severity in the middle trachea (ρ = 0.30, P = .2) and moderate in the lower trachea (ρ = 0.63, P = .002).

CONCLUSIONS

Although there is moderate agreement between flexible and rigid bronchoscopy for evaluating the presence of tracheomalacia, there can be differences in the two techniques, particularly when assessing severity of airway collapse. Future studies will be needed to understand factors that result in the discordance of flexible and rigid bronchoscopy for assessing airway dynamics.

LEVEL OF EVIDENCE

4 Laryngoscope, 131:201-204, 2021.

Ultrashort Echo-Time MRI for the Assessment of Tracheomalacia in Neonates

BACKGROUND

Bronchoscopy is the gold standard for evaluating tracheomalacia; however, reliance on an invasive procedure limits understanding of normal airway dynamics. Self-gated ultrashort echo-time MRI (UTE MRI) can assess tracheal dynamics but has not been rigorously evaluated.

METHODS

This study was a validation of UTE MRI diagnosis of tracheomalacia in neonates using bronchoscopy as the gold standard. Bronchoscopies were reviewed for the severity and location of tracheomalacia based on standardized criteria. The percent change in cross-sectional area (CSA) of the trachea between end-inspiration and end-expiration was determined by UTE MRI, and receiver-operating curves were used to determine the optimal cutoff values to predict tracheomalacia and determine positive and negative predictive values.

RESULTS

Airway segments with tracheomalacia based on bronchoscopy had a more than threefold change in CSA measured from UTE MRI (54.4 ± 56.1% vs 14.8 ± 19.5%; P < .0001). UTE MRI correlated moderately with bronchoscopy for tracheomalacia severity (ρ = 0.39; P = .0001). Receiver-operating curves, however, showed very good ability of UTE MRI to identify tracheomalacia (area under the curve, 0.78). A "loose" definition (> 20% change in CSA) of tracheomalacia had good sensitivity (80%) but low specificity (64%) for identifying tracheomalacia based on UTE MRI, whereas a "strict" definition (> 40% change in CSA) was poorly sensitive (48%) but highly specific (93%).

CONCLUSIONS

Self-gated UTE MRI can noninvasively assess tracheomalacia in neonates without sedation, ionizing radiation, or increased risk. This technique overcomes major limitations of other diagnostic modalities and may be suitable for longitudinal population studies of tracheal dynamics.

ERS statement on tracheomalacia and bronchomalacia in children

Tracheomalacia and tracheobronchomalacia may be primary abnormalities of the large airways or associated with a wide variety of congenital and acquired conditions. The evidence on diagnosis, classification and management is scant. There is no universally accepted classification of severity. Clinical presentation includes early-onset stridor or fixed wheeze, recurrent infections, brassy cough and even near-death attacks, depending on the site and severity of the lesion. Diagnosis is usually made by flexible bronchoscopy in a free-breathing child but may also be shown by other dynamic imaging techniques such as low-contrast volume bronchography, computed tomography or magnetic resonance imaging. Lung function testing can provide supportive evidence but is not diagnostic. Management may be medical or surgical, depending on the nature and severity of the lesions, but the evidence base for any therapy is limited. While medical options that include bronchodilators, anti-muscarinic agents, mucolytics and antibiotics (as well as treatment of comorbidities and associated conditions) are used, there is currently little evidence for benefit. Chest physiotherapy is commonly prescribed, but the evidence base is poor. When symptoms are severe, surgical options include aortopexy or posterior tracheopexy, tracheal resection of short affected segments, internal stents and external airway splinting. If respiratory support is needed, continuous positive airway pressure is the most commonly used modality either via a face mask or tracheostomy. Parents of children with tracheobronchomalacia report diagnostic delays and anxieties about how to manage their child's condition, and want more information. There is a need for more research to establish an evidence base for malacia. This European Respiratory Society statement provides a review of the current literature to inform future study.

Quantitative Assessment of Regional Dynamic Airway Collapse in Neonates via Retrospectively Respiratory-Gated 1 H Ultrashort Echo Time MRI

BACKGROUND

Neonatal dynamic tracheal collapse (tracheomalacia, TM) is a common and serious comorbidity in infants, particularly those with chronic lung disease of prematurity (bronchopulmonary dysplasia, BPD) or congenital airway or lung-related conditions such as congenital diaphragmatic hernia (CDH), but the underlying pathology, impact on clinical outcomes, and response to therapy are not well understood. There is a pressing clinical need for an accurate, objective, and safe assessment of neonatal TM.

PURPOSE

To use retrospectively respiratory-gated ultrashort echo-time (UTE) MRI to noninvasively analyze moving tracheal anatomy for regional, quantitative evaluation of dynamic airway collapse in quiet-breathing, nonsedated neonates.

STUDY TYPE

Prospective.

POPULATION/SUBJECTS

Twenty-seven neonatal subjects with varying respiratory morbidities (control, BPD, CDH, abnormal polysomnogram).

FIELD STRENGTH/SEQUENCE

High-resolution 3D radial UTE MRI (0.7 mm isotropic) on 1.5T scanner sited in the neonatal intensive care unit.

ASSESSMENT

Images were retrospectively respiratory-gated using the motion-modulated time-course of the k-space center. Tracheal surfaces were generated from segmentations of end-expiration/inspiration images and analyzed geometrically along the tracheal length to calculate percent-change in luminal cross-sectional area (A % ) and ratio of minor-to-major diameters at end-expiration (r D,exp ). Geometric results were compared to clinically available bronchoscopic findings (n = 14).

STATISTICAL TESTS

Two-sample t-test.

RESULTS

Maximum A % significantly identified subjects with/without a bronchoscopic TM diagnosis (with: 46.9 ± 10.0%; without: 27.0 ± 5.8%; P < 0.001), as did minimum r D,exp (with: 0.346 ± 0.146; without: 0.671 ± 0.218; P = 0.008). Subjects with severe BPD exhibited a far larger range of minimum r D,exp than subjects with mild/moderate BPD or controls (0.631 ± 0.222, 0.782 ± 0.075, and 0.776 ± 0.030, respectively), while minimum r D,exp was reduced in CDH subjects (0.331 ± 0.171) compared with controls (P < 0.001).

DATA CONCLUSION

Respiratory-gated UTE MRI can quantitatively and safely evaluate neonatal dynamic tracheal collapse, as validated with the clinical standard of bronchoscopy, without requiring invasive procedures, anesthesia, or ionizing radiation.

LEVEL OF EVIDENCE

2 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2019;49:659-667.

Helical multi-detector CT scan as a tool for diagnosing tracheomalacia in children

BACKGROUND/AIMS

Tracheomalacia (TM) is not an unusual diagnosis in pediatric respiratory clinics. The aim of this study was to assess the accuracy of paired static end-inspiratory/end-expiratory helical multi-detector CT scan (MDCT) in detecting TM.

METHODS

FB was performed in 28 children suspected of TM on the grounds of presence of recurrent episodes of vibrating cough and a need for more specific diagnostic information. Children diagnosed with flexible bronchoscopy (FB) as having TM were further investigated with MDCT. The cross-sectional area ratio of the trachea during end-expiration and end-inspiration, at the level of maximum end-expiration collapse (CSR), determined the basis for the MDCT diagnosis of TM. FB and MDCT were also performed in five children who suffered from mainly dry-but not honking, barking, or vibrating-cough for more than 3 months, and served as controls.

RESULTS

The diagnosis of TM was established bronchoscopically in 26 out of 28 children. CRS was significantly smaller in patients (0.59 ± 0.14) compared with controls (0.85 ± 0.11) (P = 0.001). The optimal CSR cut-off point for TM diagnosis, as it was estimated by the ROC curve, was ≤0.705 (95%CI: ≤0.635-≤0.850) with a sensitivity 84.6% (95%CI: 65.1-95.6), and specificity 100.0% (95%CI: 47.8-100.0).

CONCLUSIONS

MDCT can effectively diagnose TM in the majority of children and can be used as an alternative to FB. In children, the established criterion of CSR ≤0.5 should be replaced by CSR ≤0.7 that seems to be a more appropriate threshold.

Diagnostic flexible versus rigid bronchoscopy for the assessment of tracheomalacia in children

OBJECTIVE

This project compares the degree of tracheal collapse determined by rigid and flexible bronchoscopy in paediatric patients with tracheomalacia.

METHODS

A total of nine patients with tracheomalacia underwent both rigid and flexible video bronchoscopy. All patients were breathing spontaneously. Cross-sectional images of the airway were processed using the ImageJ program and analysed via colour histogram mode technique in order to delineate the luminal area. Paired t-tests (conducted using Stata software version 13.0) quantified differences between rigid and flexible bronchoscopes regarding the ratios of luminal pixels at maximum airway collapse to expansion. Correlation between both techniques in terms of airway collapse to expansion ratios was determined by calculating the Pearson correlation coefficient (R).

RESULTS

The difference in ratios of maximum collapse to expansion between rigid and flexible bronchoscopy was not statistically significant (p = 0.4656) and was positively correlated (R = 0.523).

CONCLUSION

The ratios suggest that rigid and flexible bronchoscopy are equally efficacious in assessing tracheomalacia severity, and may be used interchangeably in a clinical setting.

A systematic review of simulated laryngotracheal reconstruction animal models

OBJECTIVES

Review of the literature to identify practical, high-fidelity, commercially available animal models for simulation training and surgical skills maintenance in laryngotracheal reconstruction (LTR).

METHODS

A systematic review of PubMed and Embase databases was conducted independently by two authors, according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Search terms included "laryngotracheal reconstruction," "laryngotracheoplasty," "pig and larynx," "sheep and larynx," and "rabbit and larynx." Articles were then assessed, identifying model cost and availability, model validation, feasibility as a training tool, and verisimilitude to pediatric LTR.

RESULTS

In total, 79 articles were considered suitable for inclusion in the study, incorporating both in vitro and in vivo models. Models utilized included rabbit (n = 69), pig (n = 7), sheep (n = 1), and goat (n = 2). The rabbit model was similar in size to the neonate, but differences in laryngeal anatomy and cartilage texture made graft insertion difficult. The anatomy of the pig, sheep, and goat larynges more closely resembled the pediatric patient, allowing improved grafting, but corresponded more in size to that of an older child. Commercial availability of the pig and sheep was considered greatest, and was reflected in cost. None of the animal models identified in the literature have been validated as a simulation tool.

CONCLUSIONS

The rabbit, sheep and pig models seemed to demonstrate the greatest potential for use as advanced pediatric airway surgery simulation models, with the rabbit model being most utilized in the literature. However, as yet there have been no models formally validated as a simulation training tool. Laryngoscope, 129:235-243, 2019.

Airway dimensions from fetal life to adolescence-A literature overview

BACKGROUND

Data on airway dimensions in pediatric patients are important for proper selection of pediatric airway equipment such as endotracheal tubes, double-lumen tubes, bronchial blockers, or stents. The aim of the present work was to provide a synopsis of the available data on pediatric airway dimensions.

METHODS

A systematic literature search was carried out in the PubMed database, Scopus, Embase, Web of Science, Prisma, and Google Scholar and secondarily completed by a reference search. Based on inclusion and exclusion criteria, a final selection of 109 studies with data on pediatric airway dimensions published from 1923 to 2018 were further analyzed.

RESULTS

Six different airway measurement methods were identified. They included anatomical examinations, chest X-ray, computed tomography, magnetic resonance tomography, bronchoscopy, and ultrasound. Anatomical studies were more abundant compared to other methods. Data provided were very heterogeneously presented and powered. In addition, due to different study conditions, they are hardly comparable. Among all, anatomical and computer tomography studies are thought to provide the most reliable data. Ultrasound is an upcoming technique to estimate airway parameters of fetus and premature infants. There was, in general, a lack of comprehensive studies providing a complete range of airway dimensions in larger groups of patients from birth to adolescence.

CONCLUSIONS

This work revealed a large heterogeneity of studies providing data on pediatric airway dimensions, making it impossible to compare, or assemble them to normograms for clinical use. Comprehensive studies in large population of children are needed to provide full range nomograms on pediatric airway dimensions.

Volume relationships between cricoid and main stem bronchi in children using three-dimensional computed tomography imaging

BACKGROUND

There are limited data to guide the selection of the appropriate sized endobronchial tube for main stem intubation to provide one-lung ventilation in children. The relationship between the cricoid and the main bronchi (right and left) has been previously evaluated using two-dimensional computed tomography (CT) imaging and video-bronchoscopic images. The present study defines the three-dimensional, CT-derived volume-based relationships between the right main-stem bronchus (RMB), left main-stem bronchus (LMB), and the cricoid ring.

METHODS

The three-dimensional CT images of 35 children, less than 8 years of age, undergoing radiological evaluation unrelated to airway or mediastinal symptomatology were examined. The images of the airway column were evaluated at the level of the cricoid and main stem bronchi (right and left). Volumes were calculated and comparisons made between these levels.

RESULTS

There was no statistically significant difference based on gender for the cricoid and main stem bronchi volumes. A statistically significant difference was observed between the cricoid and left main stem bronchi volumes as well as between the right and left main stem bronchi.

CONCLUSION

The relationship (ratio) between the volumes of the cricoid and main stem bronchi remains constant by age. The cricoid dimensions can be used to predict the main stem bronchi dimensions.

Bronchoscopic assessments and clinical outcomes in pediatric patients with tracheomalacia and bronchomalacia

BACKGROUND

Tracheomalacia and bronchomalacia (TM/BM) are one of the serious causes of airway obstruction in infants and children. This study reviewed our bronchoscopic assessments and clinical outcomes in pediatric patients with TM/BM, and investigated risk factors of surgical intervention for TM/BM.

METHODS

Fifty-seven consecutive patients who were diagnosed as TM/BM by bronchoscopy between 2009 and 2013 were reviewed retrospectively. They were divided into two groups according to the presence (group E, n = 26) or absence (group N, n = 31) of acute life-threatening events and extubation failure (ALTE/EF). The severity of TM/BM was evaluated by Oblateness Index which was obtained from bronchoscopic images.

RESULTS

Oblateness Index was significantly higher in Group E than in Group N. Patients in Group E underwent surgical intervention for TM/BM more frequently, and had significantly longer intubation period and hospital stay. Clinical symptoms of ALTE/EF, Oblateness Index ≥ 0.70, and multiple malacic lesions were significant risk factors indicating surgical events in patients with TM/BM.

CONCLUSIONS

Patients with TM/BM who had ALTE/EF had more severe malacic lesions indicating surgical intervention, and worse clinical outcomes. Oblateness Index is a simple and semi-quantitative index for bronchoscopic assessment of TM/BM, and can be one of the prognostic tools to predict clinical severity of pediatric TM/BM.

A comparison of virtual bronchoscopy versus flexible bronchoscopy in the diagnosis of tracheobronchomalacia in children

INTRODUCTION

Flexible bronchoscopy (FB) is the current gold standard for diagnosing tracheobronchomalacia. However, it is not always feasible and virtual bronchoscopy (VB), acquired from chest multi-detector CT (MDCT) scan is an alternative diagnostic tool. We determined the sensitivity, specificity, and positive and negative predictive values of VB compared to FB in diagnosing tracheobronchomalacia.

METHODS

Children aged <18-years scheduled for FB and MDCT were recruited. FB and MDCT were undertaken within 30-min to 7-days of each other. Tracheobronchomalacia (mild, moderate, severe, very severe) diagnosed on FB were independently scored by two pediatric pulmonologists; VB was independently scored by two pairs (each pair = pediatric pulmonologist and radiologist), in a blinded manner.

RESULTS

In 53 children (median age = 2.5 years, range 0.8-14.3) evaluated for airway abnormalities, tracheomalacia was detected in 37 (70%) children at FB. Of these, VB detected tracheomalacia in 20 children, with a sensitivity of 54.1% (95%CI 37.1-70.2), specificity = 87.5% (95%CI 60.4-97.8), and positive predictive value = 90.9% (95%CI 69.4-98.4). The agreement between pediatric pulmonologists for diagnosing tracheomalacia by FB was excellent, weighted κ = 0.8 (95%CI 0.64-0.97); but only fair between the pairs of pediatric pulmonologists/radiologists for VB, weighted κ = 0.47 (95%CI 0.23-0.71). There were 42 cases of bronchomalacia detected on FB. VB had a sensitivity = 45.2% (95%CI 30.2-61.2), specificity = 95.5% (95%CI 94.2-96.5), and positive predictive value = 23.2 (95%CI 14.9-34.0) compared to FB in detecting bronchomalacia.

CONCLUSION

VB cannot replace FB as the gold standard for detecting tracheobronchomalacia in children. However, VB could be considered as an alternative diagnostic modality in children with symptoms suggestive of tracheobronchomalacia where FB is unavailable. Pediatr Pulmonol. 2017;52:480-486. © 2016 Wiley Periodicals, Inc.

Mild tracheal compression by aberrant innominate artery and chronic dry cough in children

BACKGROUND

In children with aberrant innominate artery (AIA) one of the most prevalent respiratory symptom is dry cough. How frequently this mediastinal vessels anomaly, that can induce tracheal compression (TC) of different degree, may be detected in children with chronic dry cough is not known.

METHODS

In a 3-year retrospective study, the occurrence of mediastinal vessels abnormalities and the presence and degree of TC was evaluated in children with recurrent/chronic dry cough.

RESULTS

Vascular anomalies were detected in 68 out of the 209 children evaluated. A significant TC was detected in 54 children with AIA, in eight with right aortic arch, in four with double aortic arch but not in two with aberrant right subclavian artery. In AIA patients, TC evaluated on computed tomography scans, was mild in 47, moderate in six and severe in one. During bronchoscopy TC increased in expiration or during cough, but this finding was more pronounced in children with right aortic arch and double aortic arch in which a concomitant tracheomalacia was more evident. Comorbidities were detected in 21 AIA patients, including atopy, reversible bronchial obstruction and gastroesophageal reflux. Aortopexy was performed in eight AIA patients, while the remaining AIA patients were managed medically and showed progressive improvement with time.

CONCLUSION

Mild TC induced by AIA can be detected in a sizeable proportion of children with recurrent/chronic dry cough. The identification of this anomaly, that may at least partially explain the origin of their symptom, may avoid further unnecessary diagnostic examinations and ineffective chronic treatments.

Measuring central airway obstruction. What do bronchoscopists do?

RATIONALE

All bronchoscopists will encounter, at some point, central airway obstruction (CAO) and will face the problem of documenting its severity. Axial imaging is suggested as the gold standard for assessing CAO, but anecdotal evidence indicates that many bronchoscopists use visual estimation. The prevalence and reliability of this method have not been extensively studied.

OBJECTIVES

This study aimed to determine bronchoscopists' opinions about assessing CAO and to assess the variability of visual estimation.

METHODS

All 438 members of the American Association of Bronchology and Interventional Pulmonology were invited to participate in an online questionnaire. In addition to reporting opinions and practice in measuring CAO, participants estimated degree of obstruction for 10 bronchoscopic photos of abnormal central airway lesions using a sliding scale from 0 to 100%.

MEASUREMENTS AND MAIN RESULTS

Responses were obtained from 118 individuals with varied interventional bronchoscopy experience. Most participants reported using visual estimation of CAO (91%) and largely by numeric estimates (87%). A total of 55 participants volunteered additional methods they employed, and their comments reflected discontent with the dependability of those. When shown the same 10 bronchoscopic photos, estimates varied considerably, with very large ranges of responses for all images. Most (86%) agreed that measurement of airway narrowing should be standardized.

CONCLUSIONS

Although limited by sample size and static photos of abnormal airways, this study supports the tenet that most bronchoscopists use a subjective and variable method of estimating CAO, which is anecdotally pervasive in the absence of a clinically practical alternative.

Toward online quantification of tracheal stenosis from videobronchoscopy

PURPOSE

Lack of objective measurement of tracheal obstruction degree has a negative impact on the chosen treatment prone to lead to unnecessary repeated explorations and other scanners. Accurate computation of tracheal stenosis in videobronchoscopy would constitute a breakthrough for this noninvasive technique and a reduction in operation cost for the public health service.

METHODS

Stenosis calculation is based on the comparison of the region delimited by the lumen in an obstructed frame and the region delimited by the first visible ring in a healthy frame. We propose a parametric strategy for the extraction of lumen and tracheal ring regions based on models of their geometry and appearance that guide a deformable model. To ensure a systematic applicability, we present a statistical framework to choose optimal parametric values and a strategy to choose the frames that minimize the impact of scope optical distortion.

RESULTS

Our method has been tested in 40 cases covering different stenosed tracheas. Experiments report a non- clinically relevant [Formula: see text] of discrepancy in the calculated stenotic area and a computational time allowing online implementation in the operating room.

CONCLUSIONS

Our methodology allows reliable measurements of airway narrowing in the operating room. To fully assess its clinical impact, a prospective clinical trial should be done.

Comparison of endoscopic versus 3D CT derived airway measurements

OBJECTIVES/HYPOTHESIS

To understand: 1) how endoscopic airway measurements compare to three-dimensional (3D) CT derived measurements; 2) where each technique is potentially useful; and 3) where each has limitations.

STUDY DESIGN

Compare airway diameters and cross-sectional areas from endoscopic images and CT derived 3D reconstructions.

METHODS

Videobronchoscopy was performed and recorded on an adult-sized commercially available airway mannequin. At various levels, cross-sectional areas were measured from still video frames using a referent placed via the biopsy port. A 3D reconstruction was generated from a high resolution CT of the mannequin; planar sections were cut at similar cross-sectional levels; and cross-sectional areas were obtained.

RESULTS

At three levels of mechanically generated tracheal stricture, the differences between the endoscopic measurement and CT-derived cross-sectional area were 1%, 0%, and 7% (1.8, 0.8, and 14 mm²). At the vocal folds, the difference was 9% (7.8 mm²). The tip of the epiglottis and width of the epiglottis differed by 27% and 10% (18.73 mm², 0.40 mm). The airway measurements at the base of tongue, minimal cross-sectional area of the pharynx, and choana differed by 26%, 36%, and 30% (101.40 mm², 36.67 mm², 122.71 mm²).

CONCLUSIONS

Endoscopy is an effective tool for obtaining airway measurements compared with 3D reconstructions derived from CT. Concordance is best in geometrically simple areas where the entire cross-section measured is visible within one field of view (trachea, round; vocal folds, triangular) versus geometrically complex areas that encompass more than one field of view (i.e. pharynx, choana).

Subjective assessment using still bronchoscopic images misclassifies airway narrowing in laryngotracheal stenosis

OBJECTIVES

Severity of airway narrowing is relevant to management decision-making processes in patients with laryngotracheal stenosis. Airway lumen is frequently assessed subjectively based on still images obtained during airway examinations or objectively using image analysis software applied to radiological or bronchoscopic images. The purpose of this study was to determine whether strictures classified as mild, moderate or severe degrees of airway narrowing based on subjective assessments by a group of experienced bronchoscopists using still images, matched the classifications derived from morphometric bronchoscopy measurements and whether the results of subjective assessments correlated with the level of bronchoscopic experience.

METHODS

Thirty-five bronchoscopic doublet still images of benign causes of laryngotracheal stenosis containing normal and abnormal airway cross-sectional areas were objectively analysed using morphometric bronchoscopy and classified as mild (<50%), moderate (50-70%) or severe (>70%). These images were then subjectively assessed by 42 experienced bronchoscopists participating in an interventional bronchoscopy course. Descriptive statistics were used to explore the accuracy of the participants' classifications. Correlation coefficients were used to study the relationship between participants' subjective assessments and bronchoscopy experience.

RESULTS

Only 47% of strictures were correctly classified by study participants (mean 16.48 ± 2.8). Of the 1447 responses included in this analysis, 755 were incorrect: 71 (9%) were over-classifications of strictures' severity and 684 (91%) were under-classifications. There was no correlation between number of strictures correctly classified and number of lifetime bronchoscopies or number of strictures seen by bronchoscopists in an average month.

CONCLUSIONS

Experienced bronchoscopists often misclassify the degree of airway narrowing when using still bronchoscopic images to subjectively assess strictures of benign aetiology.

Contralateral Deafferentation Does Not Affect Regeneration Processes in the Auditory System of Schistocerca gregaria (Orthoptera)

The auditory system of locusts has high regeneration capacity following injury of the peripheral afferents. Regenerating auditory afferents can re-innervate their target areas even after changed neuronal pathways. Here, possible influences of contralateral deafferentation on regenerating afferents were investigated. Contralateral deafferentation was performed at different stages of the regeneration. Regeneration was triggered by crushing the tympanal nerve. The regenerated fibers showed aberrant fiber outgrowth, reduced density of terminations in the target area, the auditory neuropile and collateral sprouts crossing the midline. However, these results were not significantly influenced by the contralateral deafferentation. Therefore the bilateral symmetrical systems seem to be largely independent from each other.

Changes in the auditory neuropil after deafferentation in adult grasshoppers (Schistocerca gregaria)

Nervous systems are capable of structural adjustments. Such plastic changes also occur in the auditory system of the locust Schistocerca gregaria in which a deafferentation leads to compensatory mechanisms, such as collateral sprouting of interneurons. In this study we further investigated lesion related changes in the major auditory neuropil, the median ventral association center (mVAC) of the metathoracic ganglion. The auditory sensory organ of adult locusts was unilaterally extirpated and the mVAC was histologically and immunocytochemically analyzed until 20 days postoperative. Measurements of the neuropil area in transverse sections showed a decrease in size. The putative transmitter of the afferents, acetylcholine, was investigated by acetylcholinesterase histochemistry. Comparisons of staining intensities in the intact and deafferentated mVAC indicated that the amount of acetylcholinesterase in the deafferentated mVAC decreased shortly after the operation. Both, the decreases in size of the mVAC as well as that in acetylcholinesterase histochemistry were only less than 10% compared to the controls. The immunoreactivity against the neurotransmitters gamma-amino butyric acid and serotonin was not influenced by the deafferentation.

Morphometric bronchoscopy in adults with central airway obstruction: case illustrations and review of the literature

The severity of airway narrowing impacts ventilatory function, quality of life, and choice of therapy for patients with central airway obstruction. The quantification of airway caliber remains a subjective estimate that depends on patient positioning, technique, and operator experience. In this article, we describe how morphometric bronchoscopy, a software processing method whereby bronchoscopic digital images are analyzed in order to measure airway lumen diameter, can be used to objectively quantify the degree of airway narrowing in adult patients with central airway obstruction.

Respiratory gating of anatomical optical coherence tomography images of the human airway

Anatomical optical coherence tomography (aOCT) is a long-range endoscopic imaging modality capable of quantifying size and shape of the human airway. A challenge to its in vivo application is motion artifact due to respiratory-related movement of the airway walls. This paper represents the first demonstration of respiratory gating of aOCT airway data, and introduces a novel error measure to guide appropriate parameter selection. Results indicate that at least four gates per respiratory cycle should be used, with only minor improvements as the number of gates is further increased. It is shown that respiratory gating can substantially improve the quality of aOCT images and reveal events and features that are otherwise obscured by blurring.

Using optical coherence tomography to improve diagnostic and therapeutic bronchoscopy

Flexible bronchoscopy is a common procedure that is used in both diagnostic and therapeutic settings but does not readily permit measurement of central airway dimensions. Anatomic optical coherence tomography (a OCT), a modification of conventional optical coherence tomography (OCT), is a novel light-based imaging tool with the capacity to measure the diameter and lumen area of the central airways accurately during bronchoscopy. This study describes the first clinical use of aOCT imaging in the lower airways in three individuals with common endobronchial pathologies. During bronchoscopy, a specialized fiberoptic probe was passed through the biopsy channel of a standard flexible bronchoscope to the site of airway pathology. Airway dimensions were measured from the generated cross-sectional images in three subjects, one with subglottic tracheal stenosis (subject 1), one with malignant left main bronchus (LMB) obstruction (subject 2), and another with severe tracheomalacia (subject 3). Measured dimensions included internal airway diameter, cross-sectional area, and, in subject 1, stenosis length. Tracheal stenosis dimensions, measured using aOCT imaging, correlated with chest CT scan findings and guided the choice of airway stent (subject 1). The airway beyond a malignant obstruction of the LMB, and beyond bronchoscopic view, could be imaged using aOCT, and the distal extent of obstructing tumor identified (subject 2). The severity of newly diagnosed tracheomalacia was able to be quantified using aOCT imaging (subject 3). aOCT imaging during bronchoscopy allows accurate real-time airway measurements and may assist bronchoscopic assessment.

Congenital airway lesions and lung disease

Structural upper and lower airway disorders and parenchymal disorders are uncommon in pediatric practice, but many pediatricians will encounter them and be responsible for the ongoing care of these patients. Pediatricians need to be cognizant of these diagnoses because, even though management of these disorders generally lacks an evidence base, existing principles of good care surrounding accurate diagnosis, classifications of severity, judicious use of investigations, medication, and surgical approaches are essential to good outcomes.

Upper airway dimensions in children using rigid video-bronchoscopy and a computer software: description of a measurement technique

BACKGROUND

Pediatric airway management decisions are based primarily on results derived from indirect measures of laryngeal and tracheal dimensions. More recent methods could provide more direct information about absolute and relative changes in airway dimensions associated with growth and development.

STUDY OBJECTIVES

The aims of this study were (i) to determine whether a 'video-bronchoscopic' measurement method could be used to reliably measure airway dimensions in children and (ii) to provide a preliminary assessment of dimensions of the glottis and cricoid in children of various ages.

METHODS

Following approval from the institutional review board, validation experiments were performed to determine whether measurements obtained from the video image from the bronchoscope provided accurate measurements of tubular objects of known dimensions. The reliability of the measurements was determined by using two independent trained observers to measure video-bronchoscopic images of the larynx at the level of the glottis and the cricoid in 11 children. The observers measured the video-bronchoscopic images and airway measurements were obtained in 16 additional children to determine the utility of the measurement method.

RESULTS

There was good agreement between the direct and video-bronchoscopic measurement techniques (Bland and Altman plot) for both the cross-sectional area (CSA) and the diameter of objects. The interobserver measures for cricoid and glottis were reproducible as indicated by the concordance correlation coefficient (CCC) for cricoid anteroposterior diameter (CCC = 0.98, r = 0.98, accuracy = 0.99) and transverse diameter (CCC = 0.93, r = 0.8, accuracy = 0.99) as well as for the glottic anteroposterior diameter (r = 0.8, accuracy = 0.8, CCC = 0.6) and the glottic transverse diameter(r = 0.8, accuracy = 0.74, CCC = 0.6). Overall, for the 27 children studied [mean age 73 months (+/-24.7, range 30-140], the mean value of the cricoid CSA [45.3 mm(2) (+/-13.9)] was found to be greater than the glottic CSA [16.2 mm(2) (+/-10.1)].

CONCLUSIONS

The video-bronchoscopic imaging method provided an accurate, reliable measure of pediatric airway dimensions. This technique could be applied to assess absolute and relative airway size associated with growth and development. The relationship between glottic and cricoid dimensions during growth and development in children needs further investigation across various age groups.

Distance optical sensor for quantitative endoscopy

We present a novel optical sensor able to measure the distance between the tip of an endoscopic probe and the anatomical object under examination. In medical endoscopy, knowledge of the real distance from the endoscope to the anatomical wall provides the actual dimensions and areas of the anatomical objects. Currently, endoscopic examination is limited to a direct and qualitative observation of anatomical cavities. The major obstacle to quantitative imaging is the inability to calibrate the acquired images because of the magnification system. However, the possibility of monitoring the actual size of anatomical objects is a powerful tool both in research and in clinical investigation. To solve this problem in a satisfactory way we study and realize an absolute distance sensor based on fiber optic low-coherence interferometry (FOLCI). Until now the sensor has been tested on pig trachea, simulating the real humidity and temperature (37 degrees C) conditions. It showed high sensitivity, providing correct and repeatable distance measurements on biological samples even in case of very low reflected power (down to 2 to 3 nW), with an error lower than 0.1 mm.

Longitudinal quantification of growth and changes in primary tracheobronchomalacia sites in children

RATIONALE

Longitudinal follow-up of children with tracheobronchomalacia is essential to improving our understanding of these disorders, yet currently, there is no such data.

OBJECTIVES

To longitudinally define malacia sites and quantify the cross-sectional area (CSA) of the lumen using a bronchoscopic technique and to relate these measurements to illness profiles.

METHODS

The validated color histogram mode technique was utilized to quantify primary malacia lesions and airway sites' CSA. Illness frequency, validated scales of illness and cough diary scores were prospectively used to assess clinical profiles.

RESULTS

Thirty-five malacia sites were defined from the 2 studies of 21 children. CSA of 21 (60%) of the malacia lesions increased, 5 (14%) new lesions appeared, 5 (14%) decreased in size, 3 (8%) remained unchanged, and 1(3%) was indeterminate. Overall there was no statistically significant change in paired-data assessments of malacia sites' area while there was a significant increase in area of non-malacia sites. The median yearly growth rate for the malacia sites and non-malacia was 3.65 mm2/year sites and 5.38 mm2/year, respectively (P = 0.31). The type and severity of lesion was not associated with any difference in growth rates, illness frequency or clinical scores.

CONCLUSIONS

Malacia lesions increase in size at the same rate as non-malacia sites. However malacia may worsen and new primary lesions may develop. Neither malacia type nor severity influences their growth pattern or illness profile.

Tracheostomy care in the hospital

Long-term tracheostomy in infants and children is associated with significant morbidity. The majority of paediatric patients experience tracheostomy-related complications during cannulation and/or after decannulation. A large proportion of these complications are, however, preventable or may be minimised by good tracheostomy care and clinical evaluation of the patients at regular intervals, tailored to the needs of the individual child. By and large, infants and children benefit from a specialist tracheostomy service. In this article, we review different aspects of hospital-based care, covering a wide range of topics including the selection of tracheostomy tubes and adjuncts, clinical evaluation, speech/communication, and late complications and their prevention.

Airway sizes and proportions in children quantified by a video-bronchoscopic technique

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).

Conclusion

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.