An imaging study on tracheomalacia in infants with esophageal atresia: the degree of tracheal compression by the brachiocephalic artery is a good indicator for therapeutic intervention.

PURPOSE: Tracheomalacia (TM) is a frequent complication after esophageal atresia (EA) repair. This study aimed to review patients who underwent aortopexy for TM after EA repair and to compare their imaging features. METHODS: The patients who underwent thoracoscopic EA repair and contrast-enhanced computed tomography (CECT) at our hospital between 2013 and 2020 were retrospectively reviewed. The ratio of the lateral and anterior-posterior diameter of the trachea (LAR) where the brachiocephalic artery (BCA) crosses the trachea was defined. The LAR of the patients who underwent CECT for asymptomatic pulmonary disease was set as a normal reference. The Z-score of each LAR was calculated and compared between the patients that did or did not undergo aortopexy. RESULTS: A total of 51 patients represented the controls, 5 patients underwent aortopexy, and 12 patients were discharged without surgery. The mean LARs in the patients who underwent aortopexy, did not undergo aortopexy, and controls were 3.54, 1.54, and 1.15, respectively. The mean Z-score of the aortopexy group was 21.2. After successful aortopexy, each patient's LAR decreased to < 1.5. CONCLUSION: Aortopexy was preferred if the trachea was compressed by the BCA. The LAR is a useful indicator for predicting the therapeutic effect of aortopexy.

Severe central airway stenosis and tracheomalacia in hunter syndrome.

Hunter Syndrome is a genetic disease characterized by deficiency of Iduronate-2-Sulfatase enzyme activity, resulting in accumulation of glycoaminoglycans in various organs including the central airways. We report a case of severe tracheomalacia and airway stenosis at Hospital Sultanah Aminah, Johor Bahru, Malaysia requiring mechanical ventilation in a middle aged gentleman who was previously undiagnosed of mucopolysaccharidosis. The patient underwent emergency tracheostomy for failed intubation, when he presented with shortness of breath and acute respiratory failure. A contrast-enhanced computed tomography of the neck and thorax revealed that the trachea distal to the tracheostomy tube had collapsed with narrowed right and left main bronchus. These findings were confirmed via direct visualization of the airway through a flexible bronchoscopy. Eventually, a tracheal stenting were performed to maintain the airway patency and assist in weaning off from mechanical ventilation. Further investigations to identify the aetiology of the central airway stenosis revealed elevated urinary glycoaminoglycans and the absence of iduronate-2-Sulfatase activity tested on dried blood spots, thus confirming the diagnosis of Hunter Syndrome. Managing mucopolysacharidosis with central airway obstruction requires multidisciplinary team effort in handling the difficult airway, anaesthesiology risk, potential comorbidities and providing genetic counselling.

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.

Ultralow Dose Dynamic Expiratory Computed Tomography for Evaluation of Tracheomalacia.

OBJECTIVE: The aim of this study was to determine the average effective radiation dose and feasibility of ultralow dose dynamic expiratory computed tomography (CT) for evaluation of tracheomalacia (ULD) and to evaluate factors that impact image quality. METHODS: This is a retrospective study of 64 consecutive patients from September to October 2016 for the evaluation of tracheomalacia. All studies were performed with routine inspiration chest CT followed by ULD z(kilovoltage peak (kVp) 80, 100, or 120 and fixed milliamperage 10) or typical dose CT (TD) (kVp 100 or 120 with automated milliamperage) dynamic expiration CT. Image quality was considered diagnostic if the trachea area could be accurately measured for tracheomalacia assessment, and diagnostic studies were graded fair, good, or excellent. Scan length, image quality, and effective radiation dose were compared for ULD versus TD and ULD at 100 kVp versus ULD at 80 kVp. For ULD studies, patient factors were compared across image quality. RESULTS: The ULD had a mean effective radiation dose of 0.08 mSv, with all studies of diagnostic image quality. The ULD showed 95% reduction in effective radiation dose (P < 0.001), 14% significant reduction in scan length (P = 0.029), and qualitatively decreased image quality compared w2 ith TD (P < 0.001). The ULD at 100 kVp had significantly better image quality compared with ULD at 80 kVp (P = 0.041) with higher effective radiation dose (0.09 vs 0.05 mSv) (P < 0.001). Body mass index significantly impacted image quality for all ULD studies but not for ULD at 80 or 100 kVp. CONCLUSION: For evaluation of tracheomalacia, ULD showed low effective radiation dose less than 0.1 mSv and maintained diagnostic image quality.

Refractory wheezing in Chinese children under 3 years of age: bronchial inflammation and airway malformation.

BACKGROUND: Wheezing is a common symptom in early childhood. However, refractory wheezing is difficult to treat, and it may thus account for extensive use of medical resources. It is therefore important to improve our understanding of the pathophysiology of refractory childhood wheezing. METHODS: In this descriptive study, we studied 156 children with refractory wheezing using fiberoptic bronchoscopy and bronchoalveolar lavage (BAL), and compared the results with a control group of 46 children with various pulmonary diseases but no wheezing. Etiology and cell classification were analyzed for each BAL sample. RESULTS: Overall, 21.8 % of children with refractory wheezing had airway malformations including tracheomalacia, airway stenosis, and tracheal bronchus. The incidence of airway malformations increased to 31 % in infants under 12 months of age. A significant increase in neutrophil ratio and decrease in macrophage ratio were observed in BAL from children with refractory wheezing compared with controls. Pathogen infection led to a higher ratio of neutrophils in the wheezing group compared with controls. However, there were no significant differences in neutrophil ratios among children with various pathogen infections. Furthermore, children with refractory wheezing had a high rate of Mycoplasma pneumoniae infection. CONCLUSIONS: Airway malformations might play an important role in children under 3 years of age with refractory wheezing, especially in infants under 12 months of age. Neutrophil-mediated airway inflammation was characteristic of refractory wheezing in children under 3 years of age. In addition, infections such as M. pneumoniae may aggravate airway inflammation and affect refractory wheezing.

The wonderful world of the windpipe: a review of central airway anatomy and pathology.

A variety of pathologic processes can involve the central airways. Abnormalities may either diffusely or focally involve the tracheal or mainstem bronchial walls. Diseases that diffusely involve the tracheal wall can be subclassified as sparing the membranous trachea or circumferentially involving the tracheal wall. Focal diseases of the trachea and mainstem bronchi include benign and malignant causes. Additionally, congenital and acquired morphologic abnormalities of the trachea will be reviewed.

Static end-expiratory and dynamic forced expiratory tracheal collapse in COPD.

AIM: To determine the range of tracheal collapse at end-expiration among chronic obstructive pulmonary disease (COPD) patients and to compare the extent of tracheal collapse between static end-expiratory and dynamic forced-expiratory multidetector-row computed tomography (MDCT). MATERIALS AND METHODS: After institutional review board approval and obtaining informed consent, 67 patients meeting the National Heart, Lung, and Blood Institute (NHLBI)/World Health Organization (WHO) Global Initiative for Chronic Obstructive Lung Disease (GOLD) criteria for COPD were sequentially imaged using a 64-detector-row CT machine at end-inspiration, during forced expiration, and at end-expiration. Standardized respiratory coaching and spirometric monitoring were employed. Mean percentage tracheal collapse at end-expiration and forced expiration were compared using correlation analysis, and the power of end-expiratory cross-sectional area to predict excessive forced-expiratory tracheal collapse was computed following construction of receiver operating characteristic (ROC) curves. RESULTS: Mean percentage expiratory collapse among COPD patients was 17 ± 18% at end-expiration compared to 62 ± 16% during forced expiration. Over the observed range of end-expiratory tracheal collapse (approximately 10-50%), the positive predictive value of end-expiratory collapse to predict excessive (≥80%) forced expiratory tracheal collapse was <0.3. CONCLUSION: COPD patients demonstrate a wide range of end-expiratory tracheal collapse. The magnitude of static end-expiratory tracheal collapse does not predict excessive dynamic expiratory tracheal collapse.

Dynamic airway computed tomography and flexible bronchoscopy for diagnosis of tracheomalacia in children: A comparison study.

INTRODUCTION: Tracheomalacia (TM) is an important cause of respiratory morbidity. Dynamic flexible bronchoscopy is considered the gold standard for diagnosis. Dynamic airway computed tomography (DACT) is a low radiation, noninvasive diagnostic tool utilizing images obtained continuously over several respiratory cycles. We aimed to assess the accuracy of DACT in TM diagnosis. METHODS: Retrospective analysis of all patients who underwent both DACT and flexible bronchoscopy within 6 months. Airway anterior-posterior (AP) diameter was measured on multiplanar reconstructions CT in both the inspiratory and expiratory phases. Using still images from the bronchoscopy videos, the AP diameter of the trachea was measured at points of maximal and minimal diameter during tidal breathing. Degree of TM on both DACT and flexible bronchoscopy were graded using a scaling system of 50%-74%, 75%-89%, and 90%-100% as described by the European Respiratory Society. RESULTS: Twenty-four patients met inclusion criteria with an average time of 19.5 days between CT and bronchoscopy. The specificity and sensitivity of DACT for the overall diagnosis of TM was 100% and 68%, respectively, with a positive predictive value of 100% and a negative predictive value of 62%. There was a strong positive correlation between DACT and flexible bronchoscopy in the measurement of tracheal AP diameter changes (ρ = 0.773, R2 0.597, p = 0.00001). Mean effective radiation dose for DACT was 0.1 mSv. CONCLUSION: Ultralow dose DACT has excellent specificity and positive predictive value for both detection of TM and categorizing severity of tracheal collapse but is not sufficiently sensitive to rule it out.

Acquired tracheomalacia due to SARS-CoV-2 pneumonia.

INTRODUCTION: Several studies mentioned parenchymal findings after SARS-CoV-2 pneumonia, but few studies have mentioned alterations in the airways. The aim of this study was to estimate the prevalence of tracheomalacia and to analyse the clinical characteristics in a cohort of patients with SARS-CoV-2. METHODS: The study population consisted of all patients with SARS-CoV-2 admitted a hospital serving a population of 500 000 inhabitants. Patients were visited between 2 and 6 months after hospital discharge. In this visit, all patients were subjected to an exhaustive clinical questionnaire and underwent clinical examination, pulmonary function tests and chest CT. RESULTS: From February 2020 to August 2021, 1920 patients were included in the cohort and tracheomalacia was observed in 15 (0.8%) on expiratory HRCT imaging. All patients with tracheomalacia also presented ground glass opacities in the CT scan and 12 patients had airway sequelae. CONCLUSIONS: Tracheomalacia is an exceptional sequela of SARS-CoV-2 survivors.

What's in a name? Expiratory tracheal narrowing in adults explained.

Tracheomalacia, tracheobronchomalacia, and excessive dynamic airway collapse are all terms used to describe tracheal narrowing in expiration. The first two describe luminal reduction from cartilage softening and the latter refers to luminal reduction from exaggerated posterior membrane movement. Expiratory tracheal narrowing is a frequent occurrence that can cause symptoms of airway obstruction, such as dyspnoea, wheeze, and exercise intolerance. The accurate diagnosis and quantification of expiratory tracheal narrowing has important aetiological, therapeutic, and prognostic implications. The reference standard for diagnosis has traditionally been bronchoscopy; however, this method has significant limitations. Expiratory tracheal disorders are readily detected by four-dimensional dynamic volume multidetector computed tomography (4D-CT), an emerging, non-invasive method that will potentially enable detection and quantification of these conditions. This review discusses the morphological forms of expiratory tracheal narrowing and demonstrates the utility of 4D-CT in the diagnosis, quantification, and treatment of these important conditions.

Free-breathing cine CT for the diagnosis of tracheomalacia in young children.

BACKGROUND: Tracheomalacia is characterized by excessive expiratory collapse of the trachea. OBJECTIVE: To investigate the accuracy of free-breathing cine CT for diagnosis of tracheomalacia in young children with bronchoscopy as reference standard. MATERIALS AND METHODS: In a retrospective study (May 2001-July 2008), a patient group (n = 27) of children with bronchoscopic evidence of tracheomalacia, and a control group (n = 320) underwent free-breathing cine CT. The tracheal shape on free-breathing cine CT was classified as round, lunate, elongated or crescentic. Cross-sectional area change of the trachea and age were compared between the groups and the diagnostic performance of free-breathing cine CT for tracheomalacia was evaluated. RESULTS: The patient group showed significantly greater cross-sectional area change of the trachea (57.2% ± 22.2% vs. 10.6% ± 11.2%, P < 0.001) than the control group. If a cross-sectional area change of the trachea of 31.6% was used as a cut-off value for the diagnosis of tracheomalacia, the sensitivity, specificity and accuracy of cine CT were 96.3% (26/27), 97.2% (311/320) and 97.1% (337/347), respectively. If a crescentic shape during the expiratory phase was used, the sensitivity, specificity and accuracy were 51.9% (14/27), 98.8% (316/320) and 95.1% (330/347), respectively. CONCLUSION: Free-breathing cine CT has potential to provide the diagnosis of tracheomalacia in young children.

Dynamic expiratory tracheal collapse in morbidly obese COPD patients.

Morbid obesity may influence several aspects of airway function. However, the effect of morbid obesity on expiratory tracheal collapse in COPD patients is unknown. We thus prospectively studied 100 COPD patients who underwent full pulmonary function tests (PFTs), 6-minute walk test (6MWT), Saint George's Respiratory Questionnaire (SGRQ), and low-dose CT at total lung capacity and during dynamic exhalation with spirometric monitoring. We examined correlations between percentage dynamic expiratory tracheal collapse and body mass index (BMI). The association between tracheal collapse and BMI was compared to a control group of 53 volunteers without COPD. Patients included 48 women and 52 men with mean age 65 ± 7 years; BMI 30 ± 6; FEV1 64 ± 22% predicted and percentage expiratory collapse 59 ± 19%. Expiratory collapse was significantly associated with BMI (69 ± 12% tracheal collapse among 20 morbidly obese patients with BMI ≥ 35 compared to 57 ± 19% in others, p = 0.002, t-test). In contrast, there was no significant difference in collapse between healthy volunteers with BMI ≥ 35 and < 35. COPD patients with BMI ≥ 35 also demonstrated shorter 6MWT distances (340 ± 139 m vs. 430 ± 139 m, p = 0.003) and higher (worse) total SGRQ scores (48 ± 19 vs. 36 ± 20, p = 0.013) compared to those with BMI < 35. In light of these results, clinicians should consider evaluating for excessive expiratory tracheal collapse when confronted with a morbidly obese COPD patient with greater quality of life impairment and worse exercise performance than expected based on functional measures.

Automatic segmentation and measurement of tracheal collapsibility in tracheomalacia.

PURPOSE: To assess feasibility of automated segmentation and measurement of tracheal collapsibility for detecting tracheomalacia on inspiratory and expiratory chest CT images. METHODS: Our study included 123 patients (age 67 ± 11 years; female: male 69:54) who underwent clinically indicated chest CT examinations in both inspiration and expiration phases. A thoracic radiologist measured anteroposterior length of trachea in inspiration and expiration phase image at the level of maximum collapsibility or aortic arch (in absence of luminal change). Separately, another investigator separately processed the inspiratory and expiratory DICOM CT images with Airway Segmentation component of a commercial COPD software (IntelliSpace Portal, Philips Healthcare). Upon segmentation, the software automatically estimated average lumen diameter (in mm) and lumen area (sq.mm) both along the entire length of trachea and at the level of aortic arch. Data were analyzed with independent t-tests and area under the receiver operating characteristic curve (AUC). RESULTS: Of the 123 patients, 48 patients had tracheomalacia and 75 patients did not. Ratios of inspiration to expiration phases average lumen area and lumen diameter from the length of trachea had the highest AUC of 0.93 (95% CI = 0.88-0.97) for differentiating presence and absence of tracheomalacia. A decrease of ≥25% in average lumen diameter had sensitivity of 82% and specificity of 87% for detecting tracheomalacia. A decrease of ≥40% in the average lumen area had sensitivity and specificity of 86% for detecting tracheomalacia. CONCLUSION: Automatic segmentation and measurement of tracheal dimension over the entire tracheal length is more accurate than a single-level measurement for detecting tracheomalacia.

Dynamic Volumetric Computed Tomography Angiography is an Effective Method to Evaluate Tracheomalacia in Children.

OBJECTIVE: Standard methods to evaluate tracheal pathology in children, including bronchoscopy, may require general anesthesia. Conventional dynamic proximal airway imaging in noncooperative children requires endotracheal intubation and/or medically induced apnea, which may affect airway mechanics and diagnostic performance. We describe a technique for unsedated dynamic volumetric computed tomography angiography (DV-CTA) of the proximal airway and surrounding vasculature in children and evaluate its performance compared to the reference-standard of rigid bronchoscopy. METHODS: Children who had undergone DV-CTA and bronchoscopy in one-year were retrospectively identified. Imaging studies were reviewed by an expert reader blinded to the bronchoscopy findings of primary or secondary tracheomalacia. Airway narrowing, if present, was characterized as static and/or dynamic, with tracheomalacia defined as >50% collapse of the tracheal cross-sectional area in exhalation. Pearson correlation was used for comparison. RESULTS: Over a 19-month period, we identified 32 children (median age 8 months, range 3-14 months) who had undergone DV-CTA and bronchoscopy within a 90-day period of each other. All studies were unsedated and free-breathing. The primary reasons for evaluation included noisy breathing, stridor, and screening for tracheomalacia. There was excellent agreement between DV-CTA and bronchoscopy for diagnosis of tracheomalacia (κ = 0.81, p < 0.001), which improved if children (n = 25) had the studies within 30 days of each other (κ = 0.91, p < 0.001). CTA provided incremental information on severity, and cause of secondary tracheomalacia. CONCLUSION: For most children, DV-CTA requires no sedation or respiratory manipulation and correlates strongly with bronchoscopy for the diagnosis of tracheomalacia. LEVEL OF EVIDENCE: 3 Laryngoscope, 133:410-416, 2023.

Myocardial strain in newborn infants with tracheomalacia due to vascular rings, a pilot study.

BACKGROUND: Vascular rings (VR) may cause severe tracheomalacia and upper airway obstruction (UAO). Increased pulmonary artery pressure and cardiac dysfunction have been described in patients with chronic UAO, but has not been investigated in infants with obstruction associated with VR. The aim of this study is to evaluate myocardial strain in infants with UAO due to VR. METHOD: Demographic characteristics, respiratory symptoms, percentage of tracheal obstruction measured and classified using Computer Tomography, and lung function testing (LFT) were collected. Left (LV) and right ventricle (RV) systolic functions were measured using speckle tracking echocardiography longitudinal strain analysis (LS). Pulmonary artery pressure was evaluated using maximal tricuspid regurgitation jet velocity (TR) and LV end-systolic eccentricity index (EI). RESULTS: Fifteen cases were included in the study, six had mild tracheal obstruction (<50%), nine moderate-severe obstruction (≥50%). LV LS and RV LS were significantly reduced in cases with moderate to severe airway obstruction cases compared to those with mild airway obstruction (LV LS -15.9 versus -19.9%; RV LS -15.7 versus -20.5%, p = .04 and p = .02, respectively). Respiratory symptoms were more pronounced in moderate-severe cases. No significant differences in TR, EI, and LFT were observed. CONCLUSIONS: In cases of VR with severe tracheomalacia RV and LV myocardial strain is reduced, suggesting secondary cardiac dysfunction.