Tracheomalacia and Tracheobronchomalacia in Children and Adults

Prevalence and Clinical Characteristics of Pediatric Lower Airway Malacia: Case Series from a Tertiary Center in Turkey

Introduction: Lower airway malacia (LAM) is characterized by a reduction in the cross-sectional luminal area during quiet respiration. There is no gold standard diagnostic test; however, flexible fiberoptic bronchoscopy (FFB) is most frequently utilized. The exact prevalence and incidence of LAM are unknown. This study aimed to determine the prevalence rates of pediatric patients diagnosed with LAM, offer a detailed understanding of their demographic and clinical characteristics, and investigate distinctions between two specific types of LAM, namely, tracheomalacia (TM) and bronchomalacia (BM). Materials and Methods: Patients younger than 18 years diagnosed with LAM using FFB were included in this retrospective case series. Demographic and clinical characteristics and comorbid disorders were compared between patients with isolated BM and those with isolated TM or tracheobronchomalacia (TM/TBM). Results: Among 390 patients who underwent FFB, 65 (16.6%) were diagnosed with LAM, 16 (24.6%) with TM, and 56 (86.2%) with BM. The median age at diagnosis was 15 months. Among them, 59 (90.8%) had other comorbidities; gastrointestinal (GI) disorders were the most common (38.5%). The most common indications for bronchoscopy were recurrent/prolonged lower respiratory tract infections (LRTI) or wheezing (43.1%), while the most frequently observed respiratory physical examination finding was stridor (35.4%). Patients with TM/TBM had significantly higher frequencies of premature births, stridor, retraction, and GI disorders. Conclusion: Patients with stridor without typical laryngomalacia features or recurrent or prolonged LRTI should undergo prompt evaluation for LAM. The potential coexistence of GI disorders such as gastroesophageal reflux disease and swallowing dysfunction should also be considered.

Gender differences in association between expiratory dynamic airway collapse and severity of obstructive sleep apnea

OBJECTIVES

Repetitive unbalances and tensions generated by inspiratory efforts against an obstructive upper airway during sleep predispose the development of expiratory central airway collapse. In addition, structures of the upper airway between men and women have differences and could be the reasons for differences in obstructive sleep apnea (OSA) prevalence between genders. The present study aimed to evaluate the association between parameters of expiratory dynamic tracheal collapse measured using chest multidetector CT and objectively measured OSA severity between men and women.

MATERIALS AND METHODS

A total of 901 participants who underwent chest CT and overnight in-home polysomnography from the Korean Genome and Epidemiology Study were cross-sectionally analyzed (women: 46.2%). The participants were divided into three groups based on OSA severity by apnea-hypopnea index (AHI). Multivariate linear regression analysis was performed to determine the effects of central airway collapse after adjustment for cardiovascular-related covariates.

RESULTS

In a multivariate analysis, percentages of expiratory lumen structure reductions involving area, diameter, and perimeter were associated with AHI (all p values < 0.05) and with OSA severity (moderate-to-severe OSA than no OSA: β = 3.30%, p = 0.03; β = 2.05%, p = 0.02; β = 1.97%, p = 0.02, respectively) in women, whereas men had only a greater percentage of expiratory wall thickness reduction in moderate-to-severe OSA than no OSA (β = 0.72%, p = 0.003). In addition, women with both mild OSA and moderate-to-severe OSA had higher expiratory tracheal collapse than men without OSA, and a moderate effect of sex was observed (p for interaction = 0.007).

CONCLUSION

The expiratory dynamic tracheal collapse was independently associated with severity of OSA in women than in men.

CLINICAL RELEVANCE STATEMENT

Differences of pharyngeal structures and inherent features of airways by genders may affect the dissimilarities in vulnerability to sleep apnea between men and women.

KEY POINTS

• The expiratory dynamic tracheal collapse was independently associated with severity of OSA in women than in men. • Women with over mild OSA had higher expiratory tracheal collapse than men without OSA, and moderate effect of sex was observed. • Structural differences of airway may affect differences in susceptibility of sleep apnea between genders.

Tracheobronchomalacia following allogeneic haematopoietic stem cell transplantation

Tracheobronchomalacia (TBM) occurs due to the weakening of cartilaginous part of the trachea, resulting in compromised airway function and leading to symptoms such as dyspnea, cough, and inability to clear secretions. Bronchiolitis obliterans syndrome (BOS) is the most prevalent late noninfectious pulmonary complication in patients who underwent allogeneic haematopoietic stem cell transplantation (HSCT). Therefore, patients experiencing progressive dyspnea and chronic cough after allogenic HSCT, with new obstructive pattern on pulmonary function test, are typically diagnosed with post-transplant BOS. However, it is important to note that TBM can also manifest as an obstructive defect pattern on pulmonary function test. Tracheomalacia has been reported as a rare complication of allogenic stem cell transplantation. We present two patients who developed TBM following allogeneic HSCT and were initially treated for post-transplant BOS but did not experience symptom improvement. However, after treatment with continuous positive airway pressure, their symptom subsided.

Ultralow-Dose Dynamic Expiratory CT and Repeated Imaging Enhance Evaluation for Tracheomalacia

OBJECTIVE

This study aims to determine if a novel imaging protocol (ultralow-dose dynamic expiratory computed tomography [CT] with repeated imaging) identifies tracheomalacia (TM) more reliably than traditional dynamic tracheal CT.

METHODS

We performed a retrospective evaluation of 184 consecutive ultralow-dose dynamic CTs for TM during 2017. The protocol obtains images during 1 inspiration and 2 forced expirations. Tracheal narrowing during both expirations (airway narrowing [percentage] during first dynamic expiration CT [DE1], airway narrowing [percentage] during second dynamic expiration CT [DE2]) was reported as a percentage of inspiratory area. We identified maximum narrowing of each patient's sequence (maximum narrowing [percentage] on either dynamic expiration CT [DEmax] = greatest narrowing of DE1 or DE2) and compared DE1, DE2, and DEmax in individual studies and between patients. Outcomes included frequency of TM, tracheal narrowing, and severity. Reliability was assessed by comparing tracheal area narrowing and TM grade.

RESULTS

There was significantly more airway narrowing using 2 expiratory image acquisitions. Average DEmax tracheal area was 12% narrower than DE1 alone and 21% worse than DE2 alone (both P < 0.001). Using DEmax, TM was diagnosed 35% more often than DE1 alone and 31% more often than DE2 alone ( P < 0.001). DEmax identified more severe distribution of TM compared with DE1 or DE2 alone ( P < 0.001). Reliability between DE1 and DE2 was good for tracheal narrowing and moderate for TM grade. The mean effective radiation dose was 2.41 millisievert (mSv) for routine inspiration CT and 0.07 mSv for each dynamic expiration CT (total effective radiation, 2.55 mSv).

CONCLUSIONS

Dynamic expiration CT with 2 expiratory image acquisitions enhanced evaluation of TM, minimally increased radiation dose, and should be considered as a noninvasive screening option.

Long-term pulmonary outcomes in BPD throughout the life-course

Respiratory disease is one of the most common complications of preterm birth. Survivors of prematurity have increased risks of morbidities and mortalities independent of prematurity, and frequently require multiple medications, home respiratory support, and subspecialty care to maintain health. Although advances in neonatal and pulmonary care have improved overall survival, earlier gestational age, lower birth weight, chorioamnionitis and late onset sepsis continue to be major factors in the development of bronchopulmonary dysplasia. These early life events associated with prematurity can have respiratory consequences that persist into adulthood. Furthermore, after initial hospital discharge, air pollution, respiratory tract infections and socioeconomic status may modify lung growth trajectories and influence respiratory outcomes in later life. Given that the incidence of respiratory disease associated with prematurity remains stable or increased, there is a need for pediatric and adult providers to be familiar with the natural history, manifestations, and common complications of disease.

Preoperative Workup of Patients With Excessive Central Airway Collapse: Does Stent Evaluation Serve a Role?

BACKGROUND

Tracheobronchoplasty (TBP) is a definitive anatomic intervention for patients with severe symptomatic expiratory central airway collapse. Although stent evaluations have been described for surgical workup, current literature does not address if improvement during stent evaluation is sustained after TBP. We compared health-related quality of life (HRQOL) and functional status responses after airway stenting to those post-TBP.

METHODS

A retrospective review was performed in patients with severe expiratory central airway collapse who underwent stent evaluation followed by TBP from January 2004 to December 2019. Baseline, poststent, 3- and 12-month postoperative HRQOL scores, and functional status were analyzed with statistical tests as appropriate.

RESULTS

One hundred twenty patients underwent a stent evaluation and TBP. Baseline and stent evaluation measurements were compared with statistically and clinically significant differences in the Cough Quality-of-life Questionnaire (CQLQ) (55 vs. 68, P <0.01), Modified Medical Research Council (mMRC) 0 to 2 (90% vs. 47%, P <0.01), 6-minute walk test (6MWT) (1301 ft vs. 1138 ft, P <0.01). Improvements in the HRQOL and functional status were maintained from stent evaluation to 3 months postoperatively [CQLQ 55 vs. 54, P =0.63; mMRC 0 to 2 (87% vs. 84%), P =0.39; 6MWT 1350 ft vs. 1314 ft, P =0.33], and 12 months postoperatively [CQLQ 54 vs. 54, P =0.91; mMRC 0 to 2 (95% vs. 86%), P =0.74; 6MWT 1409 ft vs. 1328 ft, P =0.13]. The magnitude of change between the data was not significantly different between the stent evaluation, 3-, and 12 months postoperative. Predicted forced expiratory volume in 1-second measurements at baseline, after stent placement, 3 months, and 12 months post-TBP were 74%, 79%, 73%, and 73%, respectively, and not clinically significant.

CONCLUSIONS

Improvement after stent evaluation and the magnitude of improvement may be predictive of postoperative outcomes up to 1 year after surgery.

Unveiling the Success of Awake Insertion of Supraglottic Airway Device for Ventilation in the Bronchoscopic Management of Tracheal Stenosis

Tracheal and subglottic stenoses are inflammatory conditions that can arise from a variety of potential etiologies, most commonly as a result of iatrogenic airway injury due to endotracheal intubation. Significant stenosis requires management by endoscopy or surgical resection. We describe a case of recurrent subglottic cuff stenosis with an episode of sudden desaturation in a 25-year-old female. The management involved balloon dilatation, laser ablation, and topical mitomycin C application through a flexible fiberoptic bronchoscope. Ensuring safe gas exchange during bronchoscopy was a priority, and this was achieved by maintaining ventilation with a supraglottic airway device, which was inserted in an awake patient after adequate tropicalization of the oral cavity. The intervention successfully helped in the management of stenosis and also addressed the complication of sudden complete airway collapse due to sedation.

The effect of bethanechol on tracheobronchomalacia in preterm infants with bronchopulmonary dysplasia: a retrospective cohort study

OBJECTIVE

Bethanechol has demonstrated improvement in trachealis tone in animal models, but no trials have studied efficacy in infants. This study aimed to examine if bethanechol improves a standardized pulmonary severity score (PSS) in infants with severe bronchopulmonary dysplasia with a diagnosis of tracheobronchomalacia (TBM).

STUDY DESIGN

This retrospective cohort study evaluated cases treated with bethanechol matched with controls who did not receive bethanechol. TBM was diagnosed by dynamic computography. Daily PSS was recorded for each infant from 40 to 55 weeks post-menstrual age.

RESULTS

Cases' mean PSS change was 21% lower than the controls' mean PSS change pre- and post-bethanechol (95% CI -40%, -2%) by paired t-test (p = 0.03). Matched differences (controls' PSS - cases' PSS) demonstrated greater mean PSS difference post-bethanechol compared to pre-bethanechol 0.17, (95% CI 0.05, 0.29) by paired t-test (p = 0.009).

CONCLUSION

Infants with TBM treated with bethanechol compared to those not treated had a lower PSS reflecting improved respiratory status.

Open and Thoracoscopic Aortopexy for Airway Malacia in Children: 15 Year Single Centre Experience

OBJECTIVES

The objective was to report and analyse the characteristics and results of open aortopexy and thoracoscopic aortopexy for the treatment of airway malacia in a paediatric population.

METHODS

We report a retrospective consecutive case series of paediatric patients undergoing aortopexy for the treatment of airway malacia at a quaternary referral centre between December 2006 and January 2021. Outcome measures included days to extubation, continued need for non-invasive ventilation, further intervention in the form of tracheostomy and death.

RESULTS

169 patients underwent aortopexy: 147 had open procedures (135 via median/limited median sternotomy and 12 thoracotomy) and 22 thoracoscopic. Mean follow up was 8.46 yrs (range 1-20 yrs). Most common site of airway malacia was the trachea (n = 106, 62.7 %), and 48 (28.4 %) had additional involvement at the bronchi with tracheobronchomalacia (TBM). 15 (8.9 %) had bronchomalacia (BM) only. Incidence of bronchial disease was lower in the thoracoscopic than open group (13.6 % vs 40.82 %; p < 0.0001). Mean time to extubation was 1.45 days, 2.59 days, 5.23 days in tracheomalacia, TBM and BM groups, respectively (p = 0.0047). Mean time to extubation was 1.35 days, 2 days, 3.67 days, and 5 days in patients with external vascular compression, TOF/OA, primary airway malacia, and laryngeal reconstruction, respectively (p = 0.0002). There were 21 deaths across the cohort, and all were in the open group. 71.4 % (n = 15) had bronchial involvement of their airway malacia.

CONCLUSIONS

Open and thoracoscopic aortopexy are effective treatments for airway malacia in children. We have identified that involvement of the bronchi is a risk factor for adverse outcomes, and the optimum treatment for this patient cohort is still debatable.

LEVEL OF EVIDENCE

IV.

TYPE OF STUDY

Retrospective Study.

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.

Pediatric Custom Tracheostomies: A Ten-Year Experience

OBJECTIVES

To describe the use of customized and custom tracheostomies at our institution, and to identify trends in patient presentation and tracheostomy design.

METHODS

A retrospective review was conducted for patients at our institution for whom a customized or custom tracheostomy tube was ordered between January 2011 and July 2021. Customized tracheostomy tubes allow for a small selection of alterations to trach design, such as cuff length and flange type. Custom tracheostomies have a unique design created by tracheostomy tube engineers in collaboration with the clinical provider, and are built specifically for a single patient.

RESULTS

A total of 235 patients were included, of whom 220 (93%) received customized tracheostomies and 15 custom (7%). The most common indications for customized tracheostomy were tracheal or stomal breakdown on a standard tracheostomy (n = 73, 33%) and ventilation difficulties (n = 61, 27%). The most frequent customization was shaft length (n = 126, 57%). The most common indication for custom tracheostomies was a persistent air leak on a standard or customized trach (n = 9) and the most frequent designs were custom cuffs (n = 8), flanges (n = 4), and anteriorly curved shafts (n = 4). Patients treated with a customized tracheostomy had a 5-year overall survival of 75.3%, compared to 51.4% for custom.

CONCLUSION

These are the first cohorts of pediatric patients with customized and custom tracheostomies to be described. Modifications to tracheostomies, in particular shaft length and cuff design, can address common complications of extended tracheostomy, and may help improve ventilation in the most challenging cases.

LEVEL OF EVIDENCE

4 Laryngoscope, 134:452-458, 2024.

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.

Surgical Innovations in Tracheal Reconstruction: A Review on Synthetic Material Fabrication

Background and Objectives: The aim of this review is to explore the recent surgical innovations in tracheal reconstruction by evaluating the uses of synthetic material fabrication when dealing with tracheomalacia or stenotic pathologies, then discussing the challenges holding back these innovations. Materials and Methods: A targeted non-systematic review of published literature relating to tracheal reconstruction was performed within the PubMed database to help identify how synthetic materials are utilised to innovate tracheal reconstruction. Results: The advancements in 3D printing to aid synthetic material fabrication have unveiled promising alternatives to conventional approaches. Achieving successful tracheal reconstruction through this technology demands that the 3D models exhibit biocompatibility with neighbouring tracheal elements by encompassing vasculature, chondral foundation, and immunocompatibility. Tracheal reconstruction has employed grafts and scaffolds, showing a promising beginning in vivo. Concurrently, the integration of resorbable models and stem cell therapy serves to underscore their viability and application in the context of tracheal pathologies. Despite this, certain barriers hinder its advancement in surgery. The intricate tracheal structure has posed a challenge for researchers seeking novel approaches to support its growth and regeneration. Conclusions: The potential of synthetic material fabrication has shown promising outcomes in initial studies involving smaller animals. Yet, to fully realise the applicability of these innovative developments, research must progress toward clinical trials. These trials would ascertain the anatomical and physiological effects on the human body, enabling a thorough evaluation of post-operative outcomes and any potential complications linked to the materials or cells implanted in the trachea.

Positional dyspnea due to excessive dynamic airway collapse: A case report

RATIONALE

Excessive dynamic airway collapse (EDAC) is a form of dynamic central airway obstruction, with characteristic of excessive dynamic invagination of airway posterior wall membrane and structurally intact airway cartilage. We report a rare case of EDAC with a marked positional component.

PATIENT CONCERNS

A 73-year-old man was admitted to our hospital owing to dyspnea in right recumbent position (RRP). Also only in RRP, strong rhonchi was auscultated bilaterally through entire respiratory phase. He had gone through 3 episodes of resections on left lung due to hemoptysis caused by bronchiectasis, so he had only segment B1 + 2 and B3 left.

DIAGNOSES

The spirometry results indicated that he had chronic obstructive pulmonary disease (COPD). The bronchoscopy revealed that in RRP, there was severe inward bulging of the posterior membrane of right main bronchus (RMB), which was worsened at expiratory phase. The EDAC of RMB was suspected, and was confirmed by an expiratory phase computed tomography (CT) in RRP. The EDAC was likely due to COPD, and the positional component was most likely to be caused by the removal of majority of his left lung.

INTERVENTIONS

Considering locality of EDAC and his overall stability, he was given a conservative approach. He was prescribed with budesonide/glycopyrrolate/formoterol for COPD and followed up.

OUTCOMES

Two months later, the patient had relived dyspnea and weaker wheezing in RRP, and he had a good social and physical recovery.

LESSONS

Dyspnea may present as a diagnostic challenge, and it is rarely accompanied with a positional component. EDAC is an uncommon cause of dyspnea. This case illustrates the possible role of bronchoscopy and dynamic CT in dynamic evaluation of airway.

Quantifiable features of a tidal breathing phenotype in dogs with severe bronchomalacia diagnosed by bronchoscopy

Dynamic lower airway obstruction is the primary component of canine bronchomalacia, but the ventilatory function remains underinvestigated. This prospective study analyzed tidal breathing characteristics in 28 dogs, comprising 14 with severe bronchomalacia diagnosed by bronchoscopy versus 14 without respiratory disease. Spirometry was conducted in all dogs. Bronchoscopy with bronchoalveolar lavage or brush under anesthesia was performed in 14 dogs with cough and expiratory effort. Severe bronchomalacia was defined by the severity of collapse and total number of bronchi affected. Ventilatory characteristics were compared between groups. Results revealed that dogs with severe bronchomalacia had lower minute volume (218 vs 338 mL/kg, p = .039) and greater expiratory-to-inspiratory time ratio (1.55 vs 1.35, p = .01) compared to control dogs. The tidal breathing pattern of dogs with bronchomalacia was different from that of normal dogs, and the pattern differed from the concave or flat expiratory curves typical of lower airway obstruction. Compared to control dogs, dogs with severe bronchomalacia had a significantly prolonged low-flow expiratory phase (p < .001) on the flow-time plot and a more exponential shape of the expiratory curve (p < .001) on the volume-time plot. Flow-time index ExpLF/Te (>0.14) and volume-time index Vt-AUCexp (≤31%) had a high ROC-AUC (1.00, 95% confidence interval 0.88 to 1.00) in predicting severe bronchomalacia. In conclusion, the tidal breathing pattern identified here indicates abnormal and complicated ventilatory mechanics in dogs with severe bronchomalacia. The role of this pulmonary functional phenotype should be investigated for disease progression and therapeutic monitoring in canine bronchomalacia.

Dynamic computed tomography for evaluation of tracheobronchomalacia in premature infants with bronchopulmonary dysplasia

INTRODUCTION

Dynamic computed tomography (dCT) gives real-time physiological information and objective descriptions of airway narrowing in tracheobronchomalacia (TBM). There is a paucity of literature in the evaluation of TBM by dCT in premature infants with bronchopulmonary dysplasia (BPD). The aim of this study is to describe the findings of dCT and resultant changes in management in premature infants with TBM.

METHODS

A retrospective study of 70 infants was performed. Infants included were <32 weeks gestation without major anomalies. TBM was defined as ≥50% expiratory reduction in cross-sectional area with severity defined as mild (50%-75%), moderate (≥75%-90%), or severe (≥90%).

RESULTS

Dynamic CT diagnosed malacia in 53% of infants. Tracheomalacia was identified in 49% of infants with severity as 76% mild, 18% moderate, and 6% severe. Bronchomalacia was identified in 43% of infants with varying severity (53% mild, 40% moderate, 7% severe). Resultant management changes included PEEP titration (44%), initiation of bethanechol (23%), planned tracheostomy (20%), extubation trial (13%), and inhaled ipratropium bromide (7%).

CONCLUSION

Dynamic CT is a useful noninvasive diagnostic tool for airway evaluation of premature infants. Presence and severity of TBM can provide actionable information to guide more precise clinical decision making.

[Interventionnal bronchoscopy for the treatment of tracheobronchomalacia]

Tracheobronchomalacia is usually characterized by more than 50% expiratory narrowing in diameter of the trachea and the bronchi. The expiratory collapse includes two entities: (1) the TBM related to the weakness of the cartilaginous rings, and (2) the Excessive Dynamic Airway Collapse (EDAC) due to the excessive bulging of the posterior membrane. Patients have nonspecific respiratory symptoms like dyspnea and cough. Diagnosis is confirmed by dynamic tests: flexible bronchoscopy and/or computed tomographic scan of the chest. There are different forms of tracheobronchomalacia in adults: primary (genetic, idiopathic) or secondary to trauma, tracheotomy, intubation, surgery, transplantation, emphysema, infection, inflammation, chronic bronchitis, extrinsic compression; or undiagnosed in childhood vascular rings. Some management algorithms have been proposed, but no specific recommendation was established. Only symptomatic patients should be treated. Medical treatments and noninvasive positive pressure ventilation should be the first line therapy, after evaluation of various quality measures (functional status, performance status, dyspnea and quality of life scores). If symptoms persist, therapeutic bronchoscopy permits: (1) patient's selection by stent trial to determine whether patient benefit for surgical airway stabilization; (2) malacic airways stenting in patients who are not surgical candidates, improving QOL despite a high complication rate; (3) the management of stent-related complication (obstruction, plugging, migration granuloma); (4) alternative therapeutics like thermo-ablative solution. Lasty, the development of new types of stents would reduce the complication rates. These different options remained discussed.

Influence of Pulsatility and Inflow Waveforms on Tracheal Airflow Dynamics in Healthy Older Adults

Tracheal collapsibility is a dynamic process altering local airflow dynamics. Patient-specific simulation is a powerful technique to explore the physiological and pathological characteristics of human airways. One of the key considerations in implementing airway computations is choosing the right inlet boundary conditions that can act as a surrogate model for understanding realistic airflow simulations. To this end, we numerically examine airflow patterns under the influence of different profiles, i.e., flat, parabolic, and Womersley, and compare these with a realistic inlet obtained from experiments. Simulations are performed in ten patient-specific cases with normal and rapid breathing rates during the inhalation phase of the respiration cycle. At normal breathing, velocity and vorticity contours reveal primary flow structures on the sagittal plane that impart strength to cross-plane vortices. Rapid breathing, however, encounters small recirculation zones. Quantitative flow metrics are evaluated using time-averaged wall shear stress (TAWSS) and oscillatory shear index (OSI). Overall, the flow metrics encountered in a real velocity profile are in close agreement with parabolic and Womersley profiles for normal conditions, however, the Womersley inlet alone conforms to a realistic profile under rapid breathing conditions.

A novel ex vivo tracheobronchomalacia model for airway stent testing and in vivo model refinement

OBJECTIVES

We sought to develop an ex vivo trachea model capable of producing mild, moderate, and severe tracheobronchomalacia for optimizing airway stent design. We also aimed to determine the amount of cartilage resection required for achieving different tracheobronchomalacia grades that can be used in animal models.

METHODS

We developed an ex vivo trachea test system that enabled video-based measurement of internal cross-sectional area as intratracheal pressure was cyclically varied for peak negative pressures of 20 to 80 cm H2O. Fresh ovine tracheas were induced with tracheobronchomalacia by single mid-anterior incision (n = 4), mid-anterior circumferential cartilage resection of 25% (n = 4), and 50% per cartilage ring (n = 4) along an approximately 3-cm length. Intact tracheas (n = 4) were used as control. All experimental tracheas were mounted and experimentally evaluated. In addition, helical stents of 2 different pitches (6 mm and 12 mm) and wire diameters (0.52 mm and 0.6 mm) were tested in tracheas with 25% (n = 3) and 50% (n = 3) circumferentially resected cartilage rings. The percentage collapse in tracheal cross-sectional area was calculated from the recorded video contours for each experiment.

RESULTS

Ex vivo tracheas compromised by single incision and 25% and 50% circumferential cartilage resection produce tracheal collapse corresponding to clinical grades of mild, moderate, and severe tracheobronchomalacia, respectively. A single anterior cartilage incision produces saber-sheath type tracheobronchomalacia, whereas 25% and 50% circumferential cartilage resection produce circumferential tracheobronchomalacia. Stent testing enabled the selection of stent design parameters such that airway collapse associated with moderate and severe tracheobronchomalacia could be reduced to conform to, but not exceed, that of intact tracheas (12-mm pitch, 0.6-mm wire diameter).

CONCLUSIONS

The ex vivo trachea model is a robust platform that enables systematic study and treatment of different grades and morphologies of airway collapse and tracheobronchomalacia. It is a novel tool for optimization of stent design before advancing to in vivo animal models.

Prevalence of tracheobronchomalacia is higher than previously reported in children with cystic fibrosis

BACKGROUND

Tracheobronchomalacia (TBM) is estimated to be present in 1 in 2100 children. Previous reports suggest the prevalence is higher in children with cystic fibrosis (CF). This has clinical implications with potential to influence airway clearance and lung health.

AIM

To determine the prevalence and clinical associations of TBM in Western Australian children with CF.

METHODS

Children with CF born between 2001 and 2016 were included. Operation reports from bronchoscopies performed until the age of 4 were retrospectively reviewed. Data were collected on the presence, persistence defined as a repeat diagnosis, and severity of TBM. Data on genotype, pancreatic status, and symptoms at CF diagnosis were extracted from the medical record. Associations between categorical variables were compared using χ2 and Fisher's exact test.

RESULTS

Of 167 children (79 male), 68 (41%) were diagnosed with TBM at least once, with TBM persistent in 37 (22%) and severe in 31 (19%). TBM was significantly associated with pancreatic insufficiency (χ2  = 7.874, p < 0.05, odds ratio [OR] 3.4), delta F508 gene mutation (χ2  = 6.489, p < 0.05, OR 2.3), and a presentation of meconium ileus (χ2  = 8.615, p < 0.05, OR 5.0). Severe malacia was less likley in females (χ2 = 4.523, p < 0.05, OR 0.42) . No significant relationship was found with respiratory symptoms at the time of CF diagnosis (χ2  = 0.742, p = 0.39).

CONCLUSIONS

TBM was common in this group of children under the age of 4 with CF. A high index of suspicion for airway malacia should be considered in children with CF, particularly those who present with meconium ileus and have gastrointestinal symptoms at diagnosis.

High-Level Spinal Cord Injury and the Failure of US Acute Rehabilitation: An Analysis and Commentary

ABSTRACT

Acute and long-term morbidity and mortality rates have not changed in the United States for people with high-level spinal cord injury in 40 yrs, neither has the conventional invasive respiratory management for these patients. This is despite a 2006 challenge to institutions for a paradigm shift to avoid or decannulate patients of tracheostomy tubes. Centers in Portugal, Japan, Mexico, and South Korea decannulate high-level patients to up to continuous noninvasive ventilatory support and use mechanical insufflation exsufflation, as we have done and reported since 1990, but there has been no such paradigm shift in US rehabilitation institutions. The quality of life and financial consequences of this are discussed. An example of decannulation of a relatively easy case, after failure to do so during 3 mos of acute rehabilitation, is presented to encourage institutions to begin to learn and apply noninvasive management before decannulating more severe patients with little to no ventilator free breathing ability.

External airway splint placement for severe pediatric tracheobronchomalacia

OBJECTIVE

To present external airway splinting with bioabsorbable airway supportive devices (ASD) for severe, life-threatening cases of pediatric tracheomalacia (TM) or tracheobronchomalacia (TBM).

METHODS

A retrospective cohort was performed for 5 pediatric patients with severe TM or TBM who underwent ASD placement. Devices were designed and 3D-printed from a bioabsorbable material, polycaprolactone (PCL). Pre-operative planning included 3-dimensional airway modeling of tracheal collapse and tracheal suture placement using nonlinear finite element (FE) methods. Pre-operative modeling revealed that triads along the ASD open edges and center were the most effective suture locations for optimizing airway patency. Pediatric cardiothoracic surgery and otolaryngology applied the ASDs by suspending the trachea to the ASD with synchronous bronchoscopy. Respiratory needs were trended for all cases. Data from pediatric patients with tracheostomy and diagnosis of TM or TBM, but without ASD, were included for discussion.

RESULTS

Five patients (2 Females, 3 Males, ages 2-9 months at time of ASD) were included. Three patients were unable to wean from respiratory support after vascular ring division; all three weaned to room air post-ASD. Two patients received tracheostomies prior to ASD placement, but continued to experience apparent life-threatening events (ALTE) and required ventilation with supraphysiologic ventilator settings. One patient weaned respiratory support successfully after ASD placement. The last patient died post-ASD due to significant respiratory co-morbidity.

CONCLUSION

ASD can significantly benefit patients with severe, unrelenting tracheomalacia or tracheobronchomalacia. Proper multidisciplinary case deliberation and selection are key to success with ASD. Pre-operative airway modeling allows proper suture placement to optimally address the underlying airway collapse.

Long-term sleep apnea CPAP via tracheostomy in children with tracheomalacia: 20-year experience

Introduction

Children with severe tracheobronchomalacia may need placements of tracheostomies and long-term mechanical ventilation. Due to financial constraints, continuous positive airway pressure (CPAP) machines commonly used to treat obstructive sleep apnea in adults have been utilized to deliver positive distending pressure to such children at our institution for more than 20 years with favorable outcomes. We, therefore, reported our experience with 15 children using this machine.

Methods

This is a retrospective study during 2001-2021.

Results

Fifteen children, 9 boys, aged ranged 3 months-5.6 years, were discharged home with CPAP via tracheostomies. All had co-morbidities including gastroesophageal reflux (n = 9, 60%), neuromuscular disorders (n = 6, 40%), genetic abnormalities (n = 6, 40%), cardiac diseases (n = 4, 27%) and chronic lungs (n = 3, 20%). Eight (53%) children were aged less than 1 year old. The smallest child was aged 3 months old, weighing 4.9 kg. All caregivers were relatives and non-medical health professionals. The 1-month and 1-year readmission rates were 13% and 66% respectively. No factor-associated unfavorable outcomes were statistically identified. No complications related to CPAP malfunction were found. Five (33%) were weaned off CPAP, and 3 died (2 from sepsis and 1 from a sudden unknown cause).

Conclusion

We first reported the use of sleep apnea CPAP via tracheostomy in children with severe tracheomalacia. In limited-resource countries, this simple device may be another option for long-term invasive ventilatory support. The CPAP use in children with tracheobronchomalacia requires adequately trained caregivers.

Computer-based airway stenosis quantification from bronchoscopic images: preliminary results from a feasibility trial

PURPOSE

Airway Stenosis (AS) is a condition of airway narrowing in the expiration phase. Bronchoscopy is a minimally invasive pulmonary procedure used to diagnose and/or treat AS. The AS quantification in a form of the Stenosis Index (SI), whether subjective or digital, is necessary for the physician to decide on the most appropriate form of treatment. The literature reports that the subjective SI estimation is inaccurate. In this paper, we propose an approach to quantify the SI defining the level of airway narrowing, using depth estimation from a bronchoscopic image.

METHODS

In this approach we combined a generative depth estimation technique combined with depth thresholding to provide Computer-based AS quantification. We performed an interim clinical analysis by comparing AS quantification performance of three expert bronchoscopists against the proposed Computer-based method on seven patient datasets.

RESULTS

The Mean Absolute Error of the subjective Human-based and the proposed Computer-based SI estimation was [Formula: see text] [%] and [Formula: see text] [%], respectively. The correlation coefficients between the CT measurements were used as the gold standard, and the Human-based and Computer-based SI estimation were [Formula: see text] and 0.46, respectively.

CONCLUSIONS

We presented a new computer method to quantify the severity of AS in bronchoscopy using depth estimation and compared the performance of the method against a human-based approach. The obtained results suggest that the proposed Computer-based AS quantification is a feasible tool that has the potential to provide significant assistance to physicians in bronchoscopy.

A single-tube-braided stent for various airway structures

Background: Airway stent has been widely used in airway procedures. However, the metallic and silicone tubular stents are not customized designed for individual patients and cannot adapt to complicated obstruction structures. Other customized stents could not adapt to complex airway structures with easy and standardized manufacturing methods.

Object: This study aimed to design a series of novel stents with different shapes which can adapt to various airway structures, such as the “Y” shape structure at the tracheal carina, and to propose a standardized fabrication method to manufacture these customized stents in the same way.

Methods: We proposed a design strategy for the stents with different shapes and introduced a braiding method to prototype six types of single-tube-braided stents. Theoretical model was established to investigate the radial stiffness of the stents and deformation upon compression. We also characterized their mechanical properties by conducting compression tests and water tank tests. Finally, a series of benchtop experiments and ex vivo experiments were conducted to evaluate the functions of the stents.

Results: The theoretical model predicted similar results to the experimental results, and the proposed stents could bear a compression force of 5.79N. The results of water tank tests showed the stent was still functioning even if suffering from continuous water pressure at body temperature for a period of 30 days. The phantoms and ex-vivo experiments demonstrated that the proposed stents adapt well to different airway structures.

Conclusion: Our study offers a new perspective on the design of customized, adaptive, and easy-to-fabricate stents for airway stents which could meet the requirements of various airway illnesses.

Improvement in postoperative lung function in patients with moderate to severe airway obstruction after robotic-assisted thoracoscopic tracheobronchoplasty

OBJECTIVE

The study objective was to examine pulmonary function and quality of life improvement after robotic-assisted thoracoscopic tracheobronchoplasty for patients with different degrees of obstructive airway disease.

METHODS

We performed a retrospective review of a prospective database of patients who underwent robotic-assisted thoracoscopic tracheobronchoplasty between 2013 and 2020.

RESULTS

A total of 118 patients underwent robotic-assisted thoracoscopic tracheobronchoplasty. Preoperative and postoperative pulmonary function tests were available for 108 patients. Postoperative pulmonary function tests at a median of 16 months demonstrated a significant increase in percent predicted forced expiratory volume in 1 second (preoperative median: 76.76% predicted, postoperative: 83% predicted, P = .002). Preoperative and postoperative St George Respiratory Questionnaires were available for 64 patients with a significant decrease in postoperative score at a median of 7 months (preoperative median: 61, postoperative: 41.60, P < .001). When stratified by preoperative degree of obstruction, robotic-assisted thoracoscopic tracheobronchoplasty improved forced expiratory volume in 1 second in moderate to very severe obstruction with a statistically significant improvement in moderate (preoperative median: 63.91% predicted, postoperative median: 73% predicted, P = .001) and severe (preoperative median: 44% predicted, postoperative median: 57% predicted, P = .007) obstruction. St George Respiratory Questionnaire scores improved for all patients. Improvement for mild (preoperative median: 61.27, postoperative median: 36.71, P < .001) and moderate (preoperative median: 57.15, postoperative median: 47.52, P = .03) obstruction was statistically significant.

CONCLUSIONS

Robotic-assisted thoracoscopic tracheobronchoplasty improves obstruction and symptoms. With limited follow-up, subgroup analysis showed forced expiratory volume in 1 second improved in severe preoperative obstruction and quality of life improved in moderate obstruction. Future follow-up is required to determine robotic-assisted thoracoscopic tracheobronchoplasty effects on the most severe group, but we cannot conclude that increased degree of preoperative obstruction precludes surgery.

Isolated Tracheabronchomalacia Misdiagnosed for Years as Bronchial Asthma

Tracheomalacia (TM) is an abnormal collapse of the tracheal lumen, which often occurs when the cartilaginous part of the trachea has not developed. It is a rare condition but is seen often in infancy and childhood period. The incidence of primary airway malacia in children was estimated to be at least one in 2,100. It has a wide range of etiologies, and it is often localized but rarely generalized as in our case. It could be severe enough to indicate frequent admission and might expose the patient to multiple unnecessary medications. We are reporting a case with unusual primary tracheobronchomalacia (TBM) that was missed for several years with a huge burden on both families and healthcare providers. A five-year-old Saudi girl had multiple admissions to the intensive care unit with similar presentation each time, and she was misdiagnosed as having asthma exacerbation with an occasional chest infection. Bronchoscopy revealed the underlying condition, and the patient was kept on the minimal intervention of nasal continuous positive airway pressure (CPAP) and aggressive airway hydration therapy, all with the goal of improving the patient's outcome and reducing hospital admissions. We emphasize the importance of alerting physicians about malacia as an important cause of recurrent wheezy chest, which is one of the common asthma mimickers; in such cases, flexible bronchoscopy remains the gold standard diagnostic test, while the treatment remained supportive.

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.

Tracheal Stent Migration in a Patient With Tracheomalacia and Tracheoesophageal Fistula: A Rare Case

Tracheomalacia refers to diffuse or segmental tracheal weakness. Most commonly, tracheomalacia develops after prolonged endotracheal intubation or tracheostomy. Surgical management is warranted in symptomatic patients with severe tracheomalacia. Relief of airway obstruction via stenting often provides immediate improvement in both airflow and symptoms. However, stent placement is associated with significant complications. Here, we present the case of a 71-year-old man who was brought to the emergency department with acute respiratory distress. The patient was known to have tracheomalacia with tracheoesophageal fistula. He had multiple medical comorbidities, including longstanding hypertension, diabetes mellitus, and asthma. The patient had a progressive decline in his level of consciousness and was admitted to the intensive care unit for further management. Despite the maximum ventilatory support, the patient did not achieve an adequate oxygenation level. The patient underwent tracheal stent placement by the interventional radiology team. The insertion was unsuccessful despite three attempts. The tracheal stent had migrated into the upper esophagus on the first and second insertion attempts. Because the patient was unstable to tolerate further attempts, the multidisciplinary team recommended the insertion of an esophageal stent to cover the tracheoesophageal fistula. Despite this, the patient continued to have air leakage with progressive worsening of his respiratory condition as he developed multiorgan failure and died. The management of tracheomalacia in the setting of the tracheoesophageal fistula may pose several challenges. The present case highlights an essential complication of stent placement with the stent migrating into the tracheoesophageal fistula, which is an unusual site of migration. A multidisciplinary approach is crucial in the management of difficult cases of tracheomalacia.

What to Expect of Feeding Abilities and Nutritional Aspects in Achondroplasia Patients: A Narrative Review

Achondroplasia is an autosomal dominant genetic disease representing the most common form of human skeletal dysplasia: almost all individuals with achondroplasia have identifiable mutations in the fibroblast growth factor receptor type 3 (FGFR3) gene. The cardinal features of this condition and its inheritance have been well-established, but the occurrence of feeding and nutritional complications has received little prominence. In infancy, the presence of floppiness and neurological injury due to foramen magnum stenosis may impair the feeding function of a newborn with achondroplasia. Along with growth, the optimal development of feeding skills may be affected by variable interactions between midface hypoplasia, sleep apnea disturbance, and structural anomalies. Anterior open bite, prognathic mandible, retrognathic maxilla, and relative macroglossia may adversely impact masticatory and respiratory functions. Independence during mealtimes in achondroplasia is usually achieved later than peers. Early supervision of nutritional intake should proceed into adolescence and adulthood because of the increased risk of obesity and respiratory problems and their resulting sequelae. Due to the multisystem involvement, oral motor dysfunction, nutrition, and gastrointestinal issues require special attention and personalized management to facilitate optimal outcomes, especially because of the novel therapeutic options in achondroplasia, which could alter the progression of this rare disease.

Ventilator-Assisted Inspiratory and Expiratory Breath-Hold Thoracic Computed Tomographic Scans Can Detect Dynamic and Static Airway Collapse in Dogs with Limited Agreement with Tracheobronchoscopy

Airway collapse (AC) in dogs includes a tracheal collapse, mainstem and lobar bronchial collapse, and bronchomalacia (i.e., segmental/subsegmental bronchial collapse). The clinical presentation of AC may overlap with non-collapsible airway disease (NCAD) or another non-lower airway respiratory disease (NLARD). This study determined whether paired inspiratory (I)/expiratory (E)-breath-hold computed tomography (I/E-BH CT) can detect a static and dynamic AC in dogs with spontaneous respiratory disease and it compared the CT-derived metrics of the AC to the tracheobronchoscopy metrics. The CT-acquired I and E diameter and cross-sectional area (CSA) for the trachea, mainstem and lobar bronchi in dogs with an AC (n = 16), NCAD (16), and NLARD (19) served for a dynamic percent of the airway narrowing (%AN) calculation. A scoring system assessed the bronchomalacia. The circularity was calculated for each airway. The results were compared to the tracheobronchoscopy collapse grading. In the dogs with an AC, the %AN was larger for the trachea, right mainstem bronchus and right middle lobar bronchus when they were compared to the dogs with NCAD and NLARD. Flattening was only identified for the trachea of the AC dogs. The agreement between the CT and tracheobronchoscopy scores was 20% from trachea to the lobar bronchi and 47% for the segmental/subsegmental bronchi. Paired I/E-BH CT can detect static and dynamic AC with limited agreement with the tracheobronchoscopy metrics. Independent scoring systems that are tailored to the clinical manifestations of functional impairments are needed.

Advances in Evaluation and Treatment of Severe Asthma (Part One)

As many as 15% to 20% of patients with asthma have incompletely or poorly controlled asthma despite treatment with inhaled corticosteroids and long-acting beta-agonist bronchodilators. They are vulnerable to burdensome symptoms, limitations to their exercise capacity, and asthma attacks that can be frightening and potentially life-threatening. This article outlines a systematic approach to their evaluation, attempting to identify remediable factors that are making their asthma more severe than most other persons with asthma. This approach includes an emphasis on ensuring the correct diagnosis, minimizing exposures to stimuli that worsen airway inflammation, alleviating modifiable comorbidities such as chronic rhinosinusitis and gastroesophageal reflux, and supporting regular medication adherence and effective technique for administering inhaled medications. A basic diagnostic laboratory work-up is recommended, to be modified and amplified according to individual patient needs.

Paediatric tracheobronchomalacia: Incidence, patient characteristics, and predictors of surgical intervention

OBJECTIVES

Tracheobronchomalacia (TBM), a condition where an abnormality of the tracheal walls causes collapse during the respiratory cycle, is a common cause of airway obstruction in childhood. TBM can present with a large spectrum of disease severity and underlying pathologies that may be managed medically and surgically, and it is not always clear which patients would most benefit from surgical intervention. We aim to describe the incidence, patient characteristics, and predictors of surgical intervention in a large cohort of paediatric patients.

METHODS

We performed a retrospective review of all children diagnosed with TBM to a paediatric Otolaryngology unit in the west of Scotland between 2010 and 2020. Odds ratios for clinical predictors of surgery were calculated using logistic regression with uni- and multivariate analysis.

RESULTS

249 patients were identified of which 219 proceeded to data collection. Primary malacia was noted in 161 (73.5%) and secondary in 58 (26.5%). Causes of secondary malacia included compression by the innominate artery (11%) and vascular rings (7.8%). Surgical interventions were performed in 28 patients (12.8%) including division of vascular ring, aortopexy, and surgical tracheostomy. Multivariate analysis showed secondary TBM, acute life-threatening events, and difficulty weaning from mechanical ventilation were independent risk factors for surgical intervention.

CONCLUSIONS

TBM can present with a myriad of airway symptoms and is frequently associated with other airway and mediastinal pathologies necessitating multiple interventions. Children aged <1 year present with a more severe form of the disease and the presence of particular independent risk factors may indicate a need for surgical intervention.

Predicting tracheal work of breathing in neonates based on radiological and pulmonary measurements

Tracheomalacia is an airway condition in which the trachea excessively collapses during breathing. Neonates diagnosed with tracheomalacia require more energy to breathe, and the effect of tracheomalacia can be quantified by assessing flow-resistive work of breathing (WOB) in the trachea using computational fluid dynamics (CFD) modeling of the airway. However, CFD simulations are computationally expensive; the ability to instead predict WOB based on more straightforward measures would provide a clinically useful estimate of tracheal disease severity. The objective of this study is to quantify the WOB in the trachea using CFD and identify simple airway and/or clinical parameters that directly relate to WOB. This study included 30 neonatal intensive care unit subjects (15 with tracheomalacia and 15 without tracheomalacia). All subjects were imaged using ultrashort echo time (UTE) MRI. CFD simulations were performed using patient-specific data obtained from MRI (airway anatomy, dynamic motion, and airflow rates) to calculate the WOB in the trachea. Several airway and clinical measurements were obtained and compared with the tracheal resistive WOB. The maximum percent change in the tracheal cross-sectional area (ρ = 0.560, P = 0.001), average glottis cross-sectional area (ρ = -0.488, P = 0.006), minute ventilation (ρ = 0.613, P < 0.001), and lung tidal volume (ρ = 0.599, P < 0.001) had significant correlations with WOB. A multivariable regression model with three independent variables (minute ventilation, average glottis cross-sectional area, and minimum of the eccentricity index of the trachea) can be used to estimate WOB more accurately (R2 = 0.726). This statistical model may allow clinicians to estimate tracheal resistive WOB based on airway images and clinical data.NEW & NOTEWORTHY The work of breathing due to resistance in the trachea is an important metric for quantifying the effect of tracheal abnormalities such as tracheomalacia, but currently requires complex dynamic imaging and computational fluid dynamics simulation to calculate it. This study produces a method to predict the tracheal work of breathing based on readily available imaging and clinical metrics.

Successful management of a tracheomalacia patient with active endotracheal bleeding due to intraoperative innominate artery injury: A case report

RATIONALE

Intraoperative innominate artery injury is life-threatening in tracheomalacia patients with prolonged tracheostomy. Anesthetic management is challenging in cases with massive hemorrhage into the endotracheal tube. We report a case in which we successfully managed a tracheomalacia patient with acute endotracheal bleeding due to innominate artery injury.

PATIENT CONCERNS

A 24-year-old patient with tracheomalacia was scheduled to undergo exploratory thoracotomy for the treatment of intermittent bleeding at the tracheostomy site. During exploration, sudden active bleeding due to innominate artery injury was observed in the endotracheal lumen.

DIAGNOSES

The patient was diagnosed with tracheomalacia.

INTERVENTIONS

We immediately used the bronchoscope to place the tip of the endotracheal tube at the bleeding site and hyperinflated the cuff.

OUTCOMES

The ballooned cuff compressed the active bleeding site, so no additional bleeding was detected by bronchoscopy, and no additional massive bleeding was observed in the operative field.

LESSONS

Immediate and appropriate overinflation of the endotracheal tube cuff by an anesthesiologist may provide improved surgical field visibility and time for critical surgical procedures in cases of massive hemorrhaging.

Novel Therapy for Acquired Tracheomalacia with a Tissue-Engineered Extraluminal Tracheal Splint and Autologous Mesenchymal-Derived Chondrocytes

Introduction Acquired tracheomalacia (ATM) is characterized by a loss of structural strength of the tracheal framework, resulting in airway collapse during breathing. Near half of the patients undergoing prolonged invasive mechanical ventilation will suffer tracheal lesions. Treatment for ATM includes external splinting with rib grafts, prosthetic materials, and tracheal resection. Failure in the use of prosthetic materials has made reconsidering natural origin scaffolds and tissue engineering as a suitable alternative.

Objective To restore adequate airway patency in an ovine model with surgically-induced ATM employing a tissue-engineered extraluminal tracheal splint (TE-ETS).

Methods In the present prospective pilot study, tracheal rings were partially resected to induce airway collapse in 16 Suffolk sheep (Ovis aries). The TE-ETS was developed with autologous mesenchymal-derived chondrocytes and allogenic decellularized tracheal segments and was implanted above debilitated tracheal rings. The animals were followed-up at 8, 12, and 16 weeks and at 1-year postinsertion. Flexible tracheoscopies were performed at each stage. After sacrifice, a histopathological study of the trachea and the splint were performed.

Results The TE-ETS prevented airway collapse for 16 weeks and up to 1-year postinsertion. Tracheoscopies revealed a noncollapsing airway during inspiration. Histopathological analyses showed the organization of mesenchymal-derived chondrocytes in lacunae, the proliferation of blood vessels, and recovery of epithelial tissue subjacent to the splint. Splints without autologous cells did not prevent airway collapse.

Conclusion It is possible to treat acquired tracheomalacia with TE-ETS without further surgical removal since it undergoes physiological degradation. The present study supports the development of tissue-engineered tracheal substitutes for airway disease.

Pediatric large airway imaging: evolution and revolution

Infants and children often present with respiratory symptoms referable to the airway. For these pediatric patients, airway imaging is frequently performed to evaluate for underlying disorders of the large airway. Various imaging modalities have been used to evaluate the pediatric large airway, and pediatric airway imaging techniques have continued to evolve. Therefore, clear understanding of the status and new advances in pediatric large airway imaging is essential for practicing radiologists to make timely and accurate diagnoses, which can lead to optimal pediatric patient management.

Surgical Management of 48 Patients with Retrosternal Goiter and Tracheal Stenosis: A Retrospective Clinical Study from a Single Surgical Center

Background

Benign retrosternal thyroid goiters can become large enough to compress the trachea and result in tracheomalacia and stenosis. This retrospective study from a single surgical center aimed to study the surgical management of 48 patients with retrosternal goiter and tracheal stenosis diagnosed and treated from January 2017 to December 2021.

Material/Methods

All preoperative contrast-enhanced CT scans showed retrosternal goiter and tracheal stenosis. RG was classified into type I in 28 patients, type II in 12 patients, and type III in 8 patients. TS was classified into grade I in 31 patients, grade II in 11 patients, and grade III in 6 patients. All patients were referred for surgery. Clinicopathologic features and surgical outcomes were recorded.

Results

All operations were successfully performed. There were 41 patients with transcervical incision, 4 with cervical incision+sternotomy, 2 with cervical incision and thoracoscopic surgery, and 1 with cervical incision and surgery via the subxiphoid approach. Two patients presented recurrent laryngeal nerve injury. One patient showed short-term hand and foot numbness. The patients were pathologically diagnosed as simple nodular goiter (n=27), nodular goiter combined with cystic change (n=6), adenomatous nodular goiter (n=10), and thyroid adenoma (n=5). There was no prominent tumor recurrence or gradual TS remission.

Conclusions

This study has highlighted that patients with retrosternal goiter and tracheal stenosis may have comorbidities and require a multidisciplinary approach to management. The choice of anesthesia, surgical approach, and maintenance of the airway during and after surgery should be individualized.

Thoracoscopic posterior tracheopexy during primary esophageal atresia repair ameliorate tracheomalacia in neonates: a single-center retrospective comparative cohort study

BACKGROUND

Esophageal atresia (EA) is often associated with tracheomalacia (TM). The severity of TM symptoms varies widely, with serious cases requiring prolonged respiratory support and surgical treatment. Although we performed thoracoscopic posterior tracheopexy (TPT) during primary EA repair to prevent or reduce the symptoms of TM, few studies have investigated the safety and effectiveness of TPT during primary EA repair. Therefore, this study aimed to evaluate the safety and efficacy of TPT in neonates.

METHODS

We retrospectively reviewed the records of all patients diagnosed with TM who underwent primary thoracoscopic EA repair between 2013 and 2020 at the Nagoya University Hospital. Patients were divided into two groups: TPT (TPT group) and without TPT (control group). TPT has been performed in all patients with EA complicated by TM since 2020. We compared patient backgrounds, surgical outcomes, postoperative complications, and treatment efficacy.

RESULTS

Of the 22 patients reviewed, eight were in the TPT group and 14 were in the control group. There were no statistically significant differences in the surgical outcomes between the groups (operation time: p = 0.31; blood loss: p = 0.83; time to extubation: p = 0.30; time to start enteral feeding: p = 0.19; time to start oral feeding: p = 0.43). Conversion to open thoracotomy was not performed in any case. The median operative time required for posterior tracheopexy was 10 (8-15) min. There were no statistically significant differences in postoperative complications between the groups (chylothorax: p = 0.36; leakage: p = 1.00; stricture: p = 0.53). The respiratory dependence rate 30 days postoperative (2 [25%] vs. 11 [79%], p = 0.03) and the ratio of the lateral and anterior-posterior diameter of the trachea (LAR) were significantly lower in the TPT group (1.83 [1.66-2.78] vs. 3.59 [1.80-7.70], p = 0.01).

CONCLUSIONS

TPT during primary EA repair for treatment of TM significantly lowered respiratory dependence rate at 30 days postoperative without increasing the risk of postoperative complications. This study suggested that TPT could improve TM associated with EA.

Tracheobronchomalacia and Excessive Dynamic Airway Collapse: Current Concepts and Future Directions

Tracheobronchomalacia (TBM) and excessive dynamic airway collapse (EDAC) are airway abnormalities that share a common feature of expiratory narrowing but are distinct pathophysiologic entities. Both entities are collectively referred to as expiratory central airway collapse (ECAC). The malacia or weakness of cartilage that supports the tracheobronchial tree may occur only in the trachea (ie, tracheomalacia), in both the trachea and bronchi (TBM), or only in the bronchi (bronchomalacia). On the other hand, EDAC refers to excessive anterior bowing of the posterior membrane into the airway lumen with intact cartilage. Clinical diagnosis is often confounded by comorbidities including asthma, chronic obstructive pulmonary disease, obesity, hypoventilation syndrome, and gastroesophageal reflux disease. Additional challenges include the underrecognition of ECAC at imaging; the interchangeable use of the terms TBM and EDAC in the literature, which leads to confusion; and the lack of clear guidelines for diagnosis and treatment. The use of CT is growing for evaluation of the morphology of the airway, tracheobronchial collapsibility, and extrinsic disease processes that can narrow the trachea. MRI is an alternative tool, although it is not as widely available and is not used as frequently for this indication as is CT. Together, these tools not only enable diagnosis, but also provide a road map to clinicians and surgeons for planning treatment. In addition, CT datasets can be used for 3D printing of personalized medical devices such as stents and splints. An invited commentary by Brixey is available online. Online supplemental material is available for this article. ^©RSNA, 2022.

Neonatal Airway Abnormalities

Neonatal airway abnormalities are commonly encountered by the neonatologist, general pediatrician, maternal fetal medicine specialist, and otolaryngologist. This review article discusses common and rare anomalies that may be encountered, along with discussion of embryology, workup, and treatment. This article aims to provide a broad overview of neonatal airway anomalies to arm those caring for these children with a broad differential diagnosis and basic knowledge of how to manage basic and complex presentations.

Association of childhood tracheomalacia with bronchiectasis: a case-control study

OBJECTIVE

Children with tracheomalacia can develop chronic lower airway infection and neutrophilic inflammation. It is plausible children with tracheomalacia are at increased risk of developing bronchiectasis. We hypothesised that compared with controls, tracheomalacia in children is associated with bronchiectasis.

DESIGN

Single-centre, case-control study.

SETTING AND PATIENTS

45 children with chest high-resolution CT (c-HRCT) confirmed bronchiectasis (cases) and enrolled in the Australian Bronchiectasis Registry were selected randomly from Queensland, and 90 unmatched children without chronic respiratory symptoms or radiographic evidence of bronchiectasis (disease controls). Cases and controls had flexible bronchoscopy performed for clinical reasons within 4 weeks of their c-HRCT.

INTERVENTIONS

The bronchoscopy videos were reviewed in a blinded manner for: (a) any tracheomalacia (any shape deformity of the trachea at end-expiration) and (b) tracheomalacia defined by the European Respiratory Society (ERS) statement (>50% expiratory reduction in the cross-sectional luminal area).

MAIN OUTCOME MEASURES AND RESULTS

Cases were younger (median age=2.6 years, IQR 1.5-4.1) than controls (7.8 years, IQR 3.4-12.8), but well-balanced for sex (56% and 52% male, respectively). Using multivariable analysis (adjusted for age), the presence of any tracheomalacia was significantly associated with bronchiectasis (adjusted OR (OR_adj)=13.2, 95% CI 3.2 to 55), while that for ERS-defined tracheomalacia further increased this risk (OR_adj=24.4, 95% CI 3.4 to infinity).

CONCLUSION

Bronchoscopic-defined tracheomalacia is associated with childhood bronchiectasis. While causality cannot be inferred, children with tracheomalacia should be monitored for chronic (>4 weeks) wet cough, the most common symptom of bronchiectasis, which if present should be treated and then investigated if the cough persists or is recurrent.

Personalized 3D-Printed Bioresorbable Airway External Splint for Tracheomalacia Combined With Congenital Heart Disease

Severe tracheomalacia (TM) patients with respiratory symptoms need surgical intervention, including aortopexy, internal stents or external splint. While some patients continue to have respiratory symptoms after tracheal relief, and there is no evidence to support any one surgery therapy over another. Here we introduce a clinical safety and efficacy of the three-dimensional (3D)-printed bioresorbable airway external splints in treating congenital heart disease (CHD) patients with severe TM. From May 2019 to September 2020, nine patients with severe TM were enrolled. The median age was 5 months (range, 3–25 months), and the median weight was 7.5 kg (range, 3–15 kg). All patients had wheezing, and two patients were assisted by machine ventilation (MV) preoperatively. The median length of TM was 1.5 cm (range, 1.0–3.0 cm). All patients underwent suspension of a “C”-shaped lumen airway external splint, which were designed in SOLIDWORKS and made of polycaprolactone (PCL). The airway external splint could provided effective support for at least 6 months and was completely degraded into carbon dioxide and water within 2–3 years. The median time of postoperative machine assisted ventilation was 23.7 h (range, 3.3–223.4 h), and the median time of ICU stay was 9 days (range, 4–25 days). The median follow-up time was 18 months (range, 12–24 months). Respiratory symptoms were all relieved, and no external splint-associated complications occurred. The 3D computed tomography reconstruction showed no airway stenosis. Personalized 3D-printed bioresorbable airway external splint can not only limit external compression and prevent airway collapse but also ensure the growth potential of the airway, which is a safe, reliable and effective treatment for CHD with TM.

Endotypes of Prematurity and Phenotypes of Bronchopulmonary Dysplasia: Toward Personalized Neonatology

Bronchopulmonary dysplasia (BPD), the chronic lung disease of prematurity, is increasingly recognized as the consequence of a pathological reparative response of the developing lung to both antenatal and postnatal injury. According to this view, the pathogenesis of BPD is multifactorial and heterogeneous with different patterns of antenatal stress (endotypes) that combine with varying postnatal insults and might distinctively damage the development of airways, lung parenchyma, interstitium, lymphatic system, and pulmonary vasculature. This results in different clinical phenotypes of BPD. There is no clear consensus on which are the endotypes of prematurity but the combination of clinical information with placental and bacteriological data enables the identification of two main pathways leading to birth before 32 weeks of gestation: (1) infection/inflammation and (2) dysfunctional placentation. Regarding BPD phenotypes, the following have been proposed: parenchymal, peripheral airway, central airway, interstitial, congestive, vascular, and mixed phenotype. In line with the approach of personalized medicine, endotyping prematurity and phenotyping BPD will facilitate the design of more targeted therapeutic and prognostic approaches.

A two-stage in vivo approach for implanting a 3D printed tissue-engineered tracheal replacement graft: A proof of concept

OBJECTIVES

To optimize a 3D printed tissue-engineered tracheal construct using a combined in vitro and a two-stage in vivo technique.

METHODS

A 3D-CAD (Computer-aided Design) template was created; rabbit chondrocytes were harvested and cultured. A Makerbot Replicator™ 2x was used to print a polycaprolactone (PCL) scaffold which was then combined with a bio-ink and the previously harvested chondrocytes. In vitro: Cell viability was performed by live/dead assay using Calcein A/Ethidium. Gene expression was performed using quantitative real-time PCR for the following genes: Collagen Type I and type II, Sox-9, and Aggrecan. In vivo: Surgical implantation occurred in two stages: 1) Index procedure: construct was implanted within a pocket in the strap muscles for 21 days and, 2) Final surgery: construct with vascularized pedicle was rotated into a segmental tracheal defect for 3 or 6 weeks. Following euthanasia, the construct and native trachea were explanted and evaluated.

RESULTS

In vitro: After 14 days in culture the constructs showed >80% viable cells. Collagen type II and sox-9 were overexpressed in the construct from day 2 and by day 14 all genes were overexpressed when compared to chondrocytes in monolayer.

IN VIVO

By day 21 (immediately before the rotation), cartilage formation could be seen surrounding all the constructs. Mature cartilage was observed in the grafts after 6 or 9 weeks in vivo.

CONCLUSION

This two-stage approach for implanting a 3D printed tissue-engineered tracheal replacement construct has been optimized to yield a high-quality, printable segment with cellular growth and viability both in vitro and in vivo.