Paediatric Tracheomalacia

"I think her life got so much better": parents' perceptions of children's quality of life following treatment of tracheomalacia with aortopexy

BACKGROUND

Aortopexy is a procedure to reduce pressure on the trachea in children with severe tracheomalacia. Health-related quality of life (HRQoL) has not been studied in children who have undergone aortopexy; we aimed to explore parents' perceptions of their child's HRQoL before and after aortopexy.

METHODS

Parents of children < 18 years who underwent aortopexy at a quaternary specialist centre were purposively sampled and invited to participate in a semi-structured interview. Data were analysed using reflective thematic and content analysis.

RESULTS

Eight interviews (23-56 min) were completed with parents whose children were aged 1.9-12.1 years. HRQoL is explored through themes: a challenging diagnosis, lifechanging, and an understanding of limitations. Parents struggled to obtain a diagnosis of tracheomalacia while their child experienced serious symptoms. Aortopexy was seen as life-saving and allowed a return to family life. Airway safety, having their health and achieving a better quality of life were important outcomes of the procedure.

CONCLUSION

Quality of life following aortopexy was perceived to be greatly improved. Children still struggled in aspects of their life, however families worked within their child's limitations, appreciating the life-saving nature of the intervention, and accepting the complexities of their child's comorbidities. Holistic interventions are important for those at risk of poor HRQoL outcomes.

Usefulness of lateral-anteroposterior dimeter ratio in patients with tracheomalacia associated with esophageal atresia

PURPOSE

Tracheomalacia (TM) is commonly associated with esophageal atresia (EA) and compression by the brachiocephalic artery is a factor for TM. Previous research has focused on the lateral-to-anteroposterior tracheal diameter ratio (LAR). This study aimed to assess the LAR and postoperative outcomes of EA patients.

METHODS

Patients undergoing thoracoscopic repair for EA between March 2020 and October 2023 were enrolled. Posterior tracheopexy (PT) was performed during thoracoscopic repair of EA on patients with bronchoscopy-confirmed TM; clinical courses and LAR were retrospectively analyzed.

RESULTS

Overall, 18 patients were enrolled; 14 patients underwent PT. Their median preoperative and postoperative LARs were 2.26 and 1.50, respectively; this difference was statistically significant. Four patients without TM did not undergo PT and their median LAR was 1.59. Median LAR for patients without PT was lower than that of preoperative patients with PT and no statistical differences were observed from that of postoperative patients with PT. The patients whose LAR improved with PT did not require further surgical intervention for TM. One patient who had a postoperative LAR of 2.25 required external tracheal stenting.

CONCLUSION

LAR is a useful index for determining the severity of TM associated with EA. LAR can reflects the efficacy of PT.

Update on aortopexy and posterior tracheopexy for tracheomalacia in patients with esophageal atresia

Despite improving the survival after repair of esophageal atresia (EA), the morbidity of EA repair remains high. Specifically, tracheomalacia (TM) is one of the most frequent complications of EA repair. Continuous positive airway pressure is generally applied for the treatment of TM. However, surgical intervention is required against an apparent life-threatening event or inability to perform extubation for a long period. According to our review, most cases of TM showed symptom improvement after aortopexy. The ratio of the trachea's lateral and anterior-posterior diameter at the brachiocephalic artery crossing the trachea, which reflects the compression of the trachea by the brachiocephalic artery, is a good indicator of aortopexy. Our finding suggests that most TM cases associated with EA may not be caused by tracheal fragility alone, but may involve blood vessel compression. Posterior tracheopexy (PT) is also an effective treatment for TM. Recently, open or thoracoscopic PT was able to be performed simultaneously with EA repair. In many cases, aortopexy or PT is a safe and effective surgical treatment for TM with EA. Other surgical procedures, such as external stenting, should be considered for patients with diffuse-type TM for whom aortopexy and PT appear relatively ineffective.

Tracheomalacia Reduces Aerosolized Drug Delivery to the Lung

Rationale: Neonates with respiratory issues are frequently treated with aerosolized medications to manage lung disease or facilitate airway clearance. Dynamic tracheal collapse (tracheomalacia [TM]) is a common comorbidity in these patients, but it is unknown whether the presence of TM alters the delivery of aerosolized drugs. Objectives: To quantify the effect of neonatal TM on the delivery of aerosolized drugs. Methods: Fourteen infant subjects with respiratory abnormalities were recruited; seven with TM and seven without TM. Respiratory-gated 3D ultrashort echo time magnetic resonance imaging (MRI) was acquired covering the central airway and lungs. For each subject, a computational fluid dynamics simulation modeled the airflow and particle transport in the central airway based on patient-specific airway anatomy, motion, and airflow rates derived from MRI. Results: Less aerosolized drug reached the distal airways in subjects with TM than in subjects without TM: of the total drug delivered, less particle mass passed through the main bronchi in subjects with TM compared with subjects without TM (33% vs. 47%, p = 0.013). In subjects with TM, more inhaled particles were deposited on the surface of the airway (48% vs. 25%, p = 0.003). This effect becomes greater with larger particle sizes and is significant for particles with a diameter >2 μm (2-5 μm, p ≤ 0.025 and 5-15 μm, p = 0.004). Conclusions: Neonatal patients with TM receive less aerosolized drug delivered to the lungs than subjects without TM. Currently, infants with lung disease and TM may not be receiving adequate and/or expected medication. Particles >2 μm in diameter are likely to deposit on the surface of the airway due to anatomical constrictions such as reduced tracheal and glottal cross-sectional area in neonates with TM. This problem could be alleviated by delivering smaller aerosolized particles.

Airway findings in trisomy 13 and trisomy 18: A 10-year retrospective review

BACKGROUND AND OBJECTIVES

Trisomy 18 and trisomy 13 are the most common autosomal trisomies following trisomy 21, with overall incidence rising. Both diagnoses are characterized by multisystem involvement and were previously thought to be incompatible with life. New data suggest that prolonged survival is possible, and thus many families are opting for more aggressive medical interventions. This study aims to describe airway findings in trisomy 18 and trisomy 13, as these have not been comprehensively studied and can impact medical decision-making. We hypothesize that most children with trisomy 18 and trisomy 13 will have abnormal findings on airway endoscopy.

METHODS

This a 10-year retrospective analysis of children with trisomy 13 or trisomy 18 who underwent endoscopic airway evaluation at a single center between 2011 and 2021. A total of 31 patients were evaluated.

RESULTS

Thirty-one patients were included and underwent flexible bronchoscopy by a pediatric pulmonologist, often in conjunction with rigid bronchoscopy performed by pediatric otolaryngology. Findings were typically complimentary. All patients had at least one clinically significant finding on evaluation, and most patients had both upper and lower airway, as well as static and dynamic airway findings. The most common airway findings in children with trisomy 13 and 18 include tracheomalacia, bronchomalacia, laryngomalacia, hypopharyngeal collapse, glossoptosis, and bronchial compression.

CONCLUSION

These findings can have significant implications for clinical care, and thus knowledge of trends has the potential to improve counseling on expected clinical course, presurgical planning, and informed consent before interventions.

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.

An Ex Vivo Model of Posterior Tracheomalacia With Evaluation of Potential Treatment Modalities

OBJECTIVE

Posterior tracheomalacia (TM) is characterized by excessive intraluminal displacement of the tracheal membranous wall. Recently, novel surgical strategies for repair of posterior TM have been introduced. To our knowledge, these strategies have not been evaluated in a model of posterior TM. Thus, we sought to design an ex vivo mechanical model of posterior TM to evaluate potential repair interventions.

METHODS

A model for posterior TM was created with partial thickness longitudinal incisions to the posterior aspect of ex vivo porcine trachea. Three groups of tracheas were tested: (1) control (unmanipulated), (2) posterior TM (injury), and (3) intervention (repair). Interventions included external splinting with 0.3 and 0.5 mm bioresorbable plates, posterior tracheopexy, and injection tracheoplasty with calcium hydroxylapatite. An airtight tracheal system was created to measure tracheal wall collapse with changes in negative pressure. A bronchoscope and pressure transducer were connected to either end. Cross-sectional area of the tracheal lumen was analyzed using ImageJ software (National Institutes of Health, Bethesda, MD).

RESULTS

Average percent reduction in cross-sectional area of the tracheal lumen was compared using a two-tailed paired t-test. Significant differences were found between control and TM groups (p < 0.019). There was no significant difference between control and external splinting and posterior tracheopexy groups (p > 0.14).

CONCLUSION

We describe an ex vivo model for posterior TM that replicates airway collapse. External splinting and tracheopexy interventions showed recovery of the injured tracheal segment. Injection tracheoplasty did not improve the TM.

LEVEL OF EVIDENCE

N/A Laryngoscope, 133:2000-2006, 2023.

Short-term outcome after the prenatal diagnosis of right aortic arch

OBJECTIVES

To determine the proportion of children that require surgery in the first year of life and thereafter in order to improve the counseling of parents with a fetus with a right aortic arch (RAA).

METHODS

Fetuses diagnosed with isolated RAA, defined as the absence of intra- or extracardiac anomalies, between 2007 and 2021 were extracted from the prospective registry PRECOR.

RESULTS

In total, 110 fetuses were included, 92 with a prenatal diagnosis of RAA and 18 with double aortic arch (DAA). The prevalence of 22q11 deletion syndrome was 5.5%. Six pregnancies were terminated and five cases were false-positive; therefore, the follow-up consisted of 99 neonates. Surgery was performed in 10 infants (10%) in the first year of life. In total, 25 (25%) children had surgery at a mean age of 17 months. Eight of these 25 (32%) had a DAA. Only one child, with a DAA, required surgery in the first week of life due to obstructive stridor.

CONCLUSIONS

Children with a prenatally diagnosed RAA are at a low risk of acute respiratory postnatal problems. Delivery in a hospital with neonatal intensive care and pediatric cardiothoracic facilities seems only indicated in cases with suspected DAA. Expectant parents should be informed that presently 25% of the children need elective surgery and only incidentally due to acute respiratory distress.

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.

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.

Microstructure and mechanics of the bovine trachea: Layer specific investigations through SHG imaging and biaxial testing

The trachea is a complex tissue made up of hyaline cartilage, fibrous tissue, and muscle fibers. Currently, the knowledge of microscopic structural organization of these components and their role in determining the tissue's mechanical response is very limited. The purpose of this study is to provide data on the microstructure of the tracheal components and its influence on tissue's mechanical response. Five bovine tracheae were used in this study. Adventitia, cartilage, mucosa/submucosa, and trachealis muscle layers were methodically cut out from the whole tissue. Second-harmonic generation(SHG) via multi-photon microscopy (MPM) enabled imaging of collagen fibers and muscle fibers. Simultaneously, a planar biaxial test rig was used to record the mechanical behavior of each layer. In total 60 samples were tested and analyzed. Fiber architecture in the adventitia and mucosa/submucosa layer showed high degree of anisotropy with the mean fiber angle varying from sample to sample. The trachealis muscle displayed neat layers of fibers organized in the longitudinal direction. The cartilage also displayed a structure of thick mesh-work of collagen type II organized predominantly towards the circumferential direction. Further, mechanical testing demonstrated the anisotropic nature of the tissue components. The cartilage was identified as the stiffest component for strain level < 20% and hence the primary load bearing component. The other three layers displayed a non-linear mechanical response which could be explained by the structure and organization of their fibers. This study is useful in enhancing the utilization of structurally motivated material models for predicting tracheal overall mechanical response.

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.

Reassessing the role of tracheobronchomalacia in persistent wheezing

BACKGROUND

Tracheobronchomalacia (TBM) is often manifested as wheezing. Reassessing the role of TBM in persistent wheezing in children is essential.

METHODS

We selected children who were diagnosed with TBM by bronchoscopy and who underwent bronchoscopic reexamination for persistent wheezing or chronic cough between January 2009 and July 2019. The clinical and bronchoscopy data were collected and retrospectively reviewed. For statistical analysis, we used the Kaplan-Meier method, Kruskal-Wallis test, and Fisher exact test.

RESULTS

A total of 79 patients (57 males and 22 females) were included. The median age of the first TBM diagnosis was 7 (interquartile [IQR] 4-11) months. The median age of the first wheezing episode was 4 (IQR 3-7) months. During the time interval between the two bronchoscopies, malacia lesions resolved in 50 patients (63.3%), improvement was seen in 14 patients (17.7%), no change was observed in 11 patients (13.9%), and the condition was aggravated in 4 patients (5.1%). The malacia lesions in 37 patients resolved before 2 years of age. Among the 50 resolved patients, 22 patients (44.0%) reported wheezing three times or more between bronchoscopy evaluations, and 13 of these 22 patients (59.1%) with atopy or family history of allergic diseases were ultimately diagnosed with bronchial asthma.

CONCLUSIONS

In children with persistent wheezing, the role of TBM should be reassessed, especially in those with atopy or family history of allergic diseases, and bronchial asthma should be considered early.

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.

When is asthma not guilty?

Asthma is a common childhood condition. Its prevalence in Saudi Arabia is high, increasing, and could exceed 20% at the current trajectory. Asthma is a syndrome with different clinical presentations and phenotypes. Many conditions are often misdiagnosed as asthma because they share the same symptoms, particularly coughing and shortness of breath; physical findings, such as wheezing; radiological findings, such as hyperinflation on chest X-ray; or even responses to asthma therapies, as in some patients with bronchiolitis. When treating the younger age group (>5 years old), there should be a high degree of suspicion of alternative causes when evaluating patients presenting with clinical features suggestive of asthma or patients who do not respond well to asthma therapies. This study will highlight common conditions that may mimic asthma and, as a result of incorrect treatment, unnecessarily expose patients to steroids and other therapies for extended periods. Furthermore, we seek to alert healthcare providers to common symptoms and signs that suggest a cause other than asthma and suggest when to refer the patient to subspecialists.

Chronic respiratory failure in bronchopulmonary dysplasia

Although survival has improved dramatically for extremely preterm infants, those with the most severe forms of bronchopulmonary dysplasia (BPD) fail to improve in the neonatal period and go on to develop chronic respiratory failure. When careful weaning of respiratory support is not tolerated, the difficult decision of whether or not to pursue chronic ventilation via tracheostomy must be made. This requires shared decision-making with an interdisciplinary medical team and the child's family. Although they suffer from increased morbidity and mortality, the majority of these children will survive to tolerate ventilator liberation and tracheostomy decannulation. Care coordination for the technology-dependent preterm infant is complex, but there is a growing consensus that chronic ventilation can best support neurodevelopmental progress and improve long-term outcomes.

Pediatric flexible bronchoscopy in the intensive care unit: A multicenter study

INTRODUCTION

Flexible bronchoscopy (FB) is frequently used for assessment and treatment of patients with respiratory diseases. Our aim was to investigate the contribution of FB to diagnosis and therapy in children admitted to the intensive care units (ICU) and to evaluate the safety of FB in this vulnerable population.

METHODS

Children less than 18 years of age who underwent FB in the five neonatal and pediatric ICUs in Istanbul between July 1st, 2015 and July 1st, 2020 were included to the study. Demographic and clinical data including bronchoscopy indications, findings, complications, and the contribution of bronchoscopy to the management were retrospectively reviewed.

RESULTS

One hundred and ninety-six patients were included to the study. The median age was 5 months (range 0.3-205 months). The most common indication of FB was extubation failure (38.3%), followed by suspected airway disease. Bronchoscopic assessments revealed at least one abnormality in 90.8% patients. The most common findings were airway malacia and the presence of excessive airway secretions (47.4% and 35.7%, respectively). Positive contribution of FB was identified in 87.2% of the patients. FB had greater than 1 positive contribution in 138 patients and 80.6% of the patients received a new diagnosis. Medical therapy was modified after the procedure in 39.8% and surgical interventions were pursued in 40% of the patients. Therapeutic lavage was achieved in 18.9%. There were no major complications.

CONCLUSION

Flexible bronchoscopy is a valuable diagnostic and therapeutic tool in neonatal and pediatric ICUs and is not associated with major complications.

Human upper-airway respiratory airflow: In vivo comparison of computational fluid dynamics simulations and hyperpolarized 129Xe phase contrast MRI velocimetry

Computational fluid dynamics (CFD) simulations of respiratory airflow have the potential to change the clinical assessment of regional airway function in health and disease, in pulmonary medicine and otolaryngology. For example, in diseases where multiple sites of airway obstruction occur, such as obstructive sleep apnea (OSA), CFD simulations can identify which sites of obstruction contribute most to airway resistance and may therefore be candidate sites for airway surgery. The main barrier to clinical uptake of respiratory CFD to date has been the difficulty in validating CFD results against a clinical gold standard. Invasive instrumentation of the upper airway to measure respiratory airflow velocity or pressure can disrupt the airflow and alter the subject's natural breathing patterns. Therefore, in this study, we instead propose phase contrast (PC) velocimetry magnetic resonance imaging (MRI) of inhaled hyperpolarized 129Xe gas as a non-invasive reference to which airflow velocities calculated via CFD can be compared. To that end, we performed subject-specific CFD simulations in airway models derived from 1H MRI, and using respiratory flowrate measurements acquired synchronously with MRI. Airflow velocity vectors calculated by CFD simulations were then qualitatively and quantitatively compared to velocity maps derived from PC velocimetry MRI of inhaled hyperpolarized 129Xe gas. The results show both techniques produce similar spatial distributions of high velocity regions in the anterior-posterior and foot-head directions, indicating good qualitative agreement. Statistically significant correlations and low Bland-Altman bias between the local velocity values produced by the two techniques indicates quantitative agreement. This preliminary in vivo comparison of respiratory airway CFD and PC MRI of hyperpolarized 129Xe gas demonstrates the feasibility of PC MRI as a technique to validate respiratory CFD and forms the basis for further comprehensive validation studies. This study is therefore a first step in the pathway towards clinical adoption of respiratory CFD.

Clinical survey and predictors for the development of tracheobronchomalacia in preterm infants

BACKGROUND

Tracheobronchomalacia (TBM) contributes to the increased morbidity and mortality observed in preterm infants. Effective strategies for the prevention of TBM are necessary to achieve better outcomes. We sought to identify risk factors associated with the development of TBM in preterm infants. Optimal cut-off values for each risk factor were also determined.

METHODS

A total of 80 infants who were born at 36 week's gestation or earlier and underwent flexible bronchoscopy were included in our study sample. A comparison of demographic and clinical risk factors between those with TBM (n = 35, 44%) and those without TBM (n = 45, 56%) was conducted using multivariate logistic regression analysis. Receiver operating characteristic curve analysis was performed to determine the appropriate cut-off values for predicting the development of TBM.

RESULTS

In the multivariate analysis, only peak inspiratory pressure (PIP) and the number of intubation days remained significantly different between infants with and without TBM. Preterm infants with TBM received higher PIP (odds ratio: [OR], 1.067; 95% confidence interval [CI], 1.010-1.128; p = .020) and were intubated for longer (odds ratio [OR], 1.019; 95% CI, 1.003-1.035; p = .016) than those without TBM. Infants who received PIP > 19.5 cmH₂ O or were intubated for >79.5 days were associated with a significantly higher risk of presence of TBM.

CONCLUSION

High PIP and prolonged intubation were major risk factors for the development of TBM in premature infants. Those who require PIP > 19.5 cmH₂ O or intubation >79.5 days warrant bronchoscopy examination for early diagnosis and management of TBM.

Endoscopically Applied Biodegradable Stent in a Rabbit Model of Pediatric Tracheomalacia

OBJECTIVES

A polydioxanone (PDO) stent was developed to treat tracheomalacia in pediatric patients. However, its safety and efficacy need to be verified in animal studies before clinical trials in patients can be conducted. This study evaluated the safety and efficacy of a PDO stent in normal and tracheomalacia-model rabbits.

METHODS

In total, 29 New Zealand white rabbits were used: 13 for evaluating the biocompatibility of the PDO stent in normal rabbits and 16 for the creation of a tracheomalacia model. The tracheomalacia model was successfully established in 12 rabbits, and PDO stents were placed in eight of those rabbits.

RESULTS

The PDO stent was successfully positioned in the trachea of the normal rabbits using an endoscopic approach, and its degradation was observed 10 weeks later. The stent fragments did not induce distal airway obstruction or damage, and the mucosal changes that occurred after stent placement were reversed after degradation. The same procedure was performed on the tracheomalacia-model rabbits. The survival duration of the tracheomalacia rabbits with and without stents was 49.0±6.8 and 1.0±0.8 days, respectively. Thus, the PDO stent yielded a significant survival gain (P=0.001). In the tracheomalacia rabbits, stent degradation and granulation tissue were observed 7 weeks after placement, leading to airway collapse and death.

CONCLUSION

We successfully developed a PDO stent and an endoscopic guide placement system. The degradation time of the stent was around 10 weeks in normal rabbits, and its degradation was accelerated in the tracheomalacia model. The mucosal changes associated with PDO stent placement were reversible. Placement of the PDO stent prolonged survival in tracheomalacia-model rabbits.

Primary Posterior Tracheopexy in Esophageal Atresia Decreases Respiratory Tract Infections

Background: Esophageal atresia (EA) is often accompanied by tracheomalacia (TM). TM can lead to severe respiratory complaints requiring invasive treatment. This study aims to evaluate if thoracoscopic primary posterior tracheopexy (PPT) can prevent the potential sequelae of TM in patients with EA. Methods: A cohort study including all consecutive EA patients treated between 2014 and July 2019 at the Wilhelmina Children's Hospital was conducted. Two groups were distinguished: (group 1) all EA patients born between January 2014 and December 2016 and (group 2) all EA patients born between January 2017 and July 2019, after introduction of PPT. In the latter group, PPT was performed in EA patients with moderate (33-66%) or severe (67-100%) tracheomalacia, seen during preoperative bronchoscopy. Group differences were assessed using the Fisher's exact test for bivariate variables and the Mann-Whitney U-test for continuous variables. Results: A total of 64 patients were included in this study (28 patients in group 1; 36 patients in group 2). In group 2, PPT was performed in 14 patients. Respiratory tract infections (RTIs) requiring antibiotics within the first year of life occurred significantly less in group 2 (61 vs. 25%, p = 0.004). Brief resolved unexplained events (BRUEs) seemed to diminish in group 2 compared to group 1 (39 vs. 19%, p = 0.09). Conclusion: Thoracoscopic primary posterior tracheopexy decreases the number of respiratory tract infections in EA patients. The clinical impact of reducing RTIs combined with the minimal additional operating time and safety of PPT outweighs the risk of overtreatment.

Risk Factors for Tracheobronchomalacia in Preterm Infants With Bronchopulmonary Dysplasia

Aim: To identify the risk factors associated with the development of tracheobronchomalacia (TBM) in preterm infants with bronchopulmonary dysplasia (BPD). Methods: This was a retrospective cohort study using chart reviews of preterm infants born at ≤ 36 week's gestation who underwent flexible fiberoptic bronchoscopy in a tertiary pediatric referral center between January 2015 and January 2020. Indications for the bronchoscopy examination included lobar atelectasis on plain chest film, persistent CO₂ retention, recurrent extubation failure, or abnormal breathing sounds such as wheeze or stridor. Optimal cutoff values for each risk factor were also determined. Results: Fifty-eight preterm infants with BPD were enrolled, of whom 29 (50%) had TBM. There were no significant differences in gestational age and birth weight between those with and without TBM. Significantly more of the patients with TBM had severe BPD compared to those without TBM (68.9 vs. 20.6%, p < 0.001). Clinical parameters that were significantly different between the two groups were included in multivariate analysis. Among these factors, severe BPD was the most powerful risk factor for the development of TBM (odds ratio 5.57, 95% confidence interval 1.32-23.5, p = 0.019). The areas under the receiver operating characteristic curves for peak inspiratory pressure (PIP) and the duration of intubation were 0.788 and 0.75, respectively. The best predictive cutoff values of PIP and duration of intubation for TBM were 18.5 mmHg and 82 days, respectively. Conclusion: Preterm infants with severe BPD are at high risk for the development of TBM, and the risk is even higher in those who receive a higher PIP or are intubated for longer. Bronchoscopy examinations should be considered for the early diagnosis and management of TBM in infants with these risk factors.

Cleft-lip-plate patient with tracheobronchomalacia: A case report and review of the literature in Japan

Background

Tracheobronchomalacia (TBM) is a severe life-threatening perioperative complication. It is a rare condition caused by congenital and developmental anomalies of the trachea and/or the bronchus. It is often difficult to diagnose TBM before surgery as this congenital disease presents very few symptoms preoperatively and most often appears postoperatively.

Case presentation and Review

The study describes a case of cleft-lip-plate (CL/P) in a 7-month-old Japanese female with TBM and Tetralogy of Fallot syndrome. Before undergoing cleft-lip surgery, her TBM was not fully elucidated by preoperative examinations, and the operation was completed uneventfully. After the surgery, however, she started showing severe respiratory distress and developed hypoxia and bradycardia in the operating room. CPR was performed successfully, but a bronchoscopy revealed a severely collapsed airway, and the pathological condition was diagnosed as TBM occurred postoperatively. Eight months later, she died of sudden respiratory failure similar to that of the postoperative event caused by TBM. A literature review was conducted on the complications of CL/P from 1990 to 2017 in Japan.

Conclusions

It was hypothesized that CL/P with congenital heart disease (CHD) and TBM with CHD may crossover in relatively high rates. Currently, there are very few solutions available to treat severe airway obstruction related to TBM. This highlights the need for preoperative diagnosis of TBM as an important step in overcoming severe airway complications.

MRI of the upper airways in children and young adults: the MUSIC study

RATIONALE

Paediatric laryngotracheal stenosis (LTS) is often successfully corrected with open airway surgery. However, respiratory and vocal sequelae frequently remain. Clinical care and surgical interventions could be improved with better understanding of these sequelae.

OBJECTIVE

The objective of this cross-sectional study was to develop an upper airway MRI protocol to obtain information on anatomical and functional sequelae post-LTS repair.

METHODS

Forty-eight patients (age 14.4 (range 7.5-30.7) years) and 11 healthy volunteers (15.9 (8.2-28.8) years) were included. Spirometry and static and dynamic upper airway MRI (3.0 T, 30 min protocol) were conducted. Analysis included assessment of postoperative anatomy and airway lumen measurements during static and dynamic (inspiration and phonation) acquisitions.

MAIN RESULTS

Good image quality without artefacts was achieved for static and dynamic images in the majority of MRIs. MRI showed vocal cord thickening in 80.9% of patients and compared with volunteers, a significant decrease in vocal cord lumen area (22.0 (IQR 17.7-30.3) mm² vs 35.1 (21.2-54.7) mm², p=0.03) but not cricoid lumen area (62.3±27.0 mm² vs 66.2±34.8 mm², p=0.70). Furthermore, 53.2% of patients had an A-frame deformation at site of previous tracheal cannula, showing lumen collapse during inspiration. Dynamic imaging showed incomplete vocal cord abduction during inspiration in 42.6% and incomplete adduction during phonation in 61.7% of patients.

CONCLUSIONS

Static and dynamic MRI is an excellent modality to non-invasively image anatomy, tissue characteristics and vocal cord dynamics of the upper airways. MRI-derived knowledge on postsurgical LTS sequelae might be used to improve surgery.

The clinical safety and efficacy of flexible bronchoscopy in a neonatal intensive care unit

Flexible bronchoscopy (FB), developed in the 1960s, is widely used in the clinical practice of pediatrics and has demonstrated fundamental value in clinical diagnoses and treatment. However, as an invasive procedure, the use of FB is limited due to concerns regarding the tolerance of the procedure and the possible complications in neonatal units. Thus, the present study aimed to investigate the clinical safety and efficacy of flexible bronchoscopy (FB) in a neonatal intensive care unit (NICU). Neonates (n=54) who received FB in the NICU of Shanghai Children's Hospital between January 2012 and December 2016 were enrolled as the experimental group and another 54 neonates who required nebulization and tracheal secretion suction treatments were the control group. Indicators including blood gas, complete blood count, C-reactive protein (CRP), X-ray, patient breathing rate, temperature and blood pressure were monitored prior to and following the procedure. No significant differences in sex, gestational age, birth weight or postnatal age were observed between the experimental group and the control group (P>0.05). Among the 54 FB patients, several cases with side effect were identified, including 18 (33.3%) with respiratory tract stenosis, nine (16.7%) with malacia and stenosis and six (11.1%) with esophagotracheal fistula. Among the 54 members of the control group, 44 neonates (81.4%) were discharged with improved condition, five (9.3%) succumbed and five patients (9.3%) abandoned the treatment and left the hospital. Bronchoalveolar lavage demonstrated consistent results with respiratory secretion culture or tracheal tube culture. In comparison between the experimental and the control groups, no significant difference in pH, partial pressure of carbon dioxide (PCO₂), partial pressure of oxygen (PO₂) and HCO₃ ^- was observed, while there were no statistical differences in the values of pH, PCO₂ and HCO₃ ^- (P>0.05). However, PO₂ was significantly increased, and CRP was significantly reduced, following FB procedure compared with prior to FB (P<0.05). No pneumothorax, shock, other severe complications, fever or diffused pneumonia were observed during or after FB. The data from the present study demonstrated that FB is a safe and effective strategy for the diagnosis and differentiation of neonatal respiratory diseases in NICU.

Phenotypes of Bronchopulmonary Dysplasia

Bronchopulmonary dysplasia (BPD) is the most common chronic morbidity in preterm infants. In the absence of effective interventions, BPD is currently a major therapeutic challenge. Several risk factors are known for this multifactorial disease that results in disrupted lung development. Inflammation plays an important role and leads to persistent airway and pulmonary vascular disease. Since corticosteroids are potent anti-inflammatory agents, postnatal corticosteroids have been used widely for BPD prevention and treatment. However, the clinical responses vary to a great degree across individuals, and steroid-related complications remain major concerns. Emerging studies on the molecular mechanism of lung alveolarization during inflammatory stress will elucidate the complicated pathway and help discover novel therapeutic targets. Moreover, with the advances in metabolomics, there are new opportunities to identify biomarkers for early diagnosis and prognosis prediction of BPD. Pharmacometabolomics is another novel field aiming to identify the metabolomic changes before and after a specific drug treatment. Through this "metabolic signature," a more precise treatment may be developed, thereby avoiding unnecessary drug exposure in non-responders. In the future, more clinical, genetic, and translational studies would be required to improve the classification of BPD phenotypes and achieve individualized care to enhance the respiratory outcomes in preterm infants.

Differences in Flexible and Rigid Bronchoscopy for Assessment of Tracheomalacia

OBJECTIVES/HYPOTHESIS

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

STUDY DESIGN

Retrospective case series.

METHODS

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

RESULTS

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

CONCLUSIONS

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

LEVEL OF EVIDENCE

4 Laryngoscope, 131:201-204, 2021.

"Tracheomalacia after Thyroidectomy," Does it Truly Exist?

Aim:

Tracheomalacia is a potentially life-threatening, but a rare complication of thyroidectomy. In previous studies, the incidence rate was very different. Considering the relatively high prevalence of goiter and thyroidectomy in the West Azerbaijan region, we designed this study to determine the tracheomalacia incidence in patients who underwent thyroidectomy within a 10-year interval.

Materials and Methods:

This retrospective study was done in Urmia Imam Khomeini Hospital in West Azarbayjan Province. Demographic characteristics including the age and sex of patients who underwent thyroidectomy between 2007 and 2017 and also the incidence of tracheomalacia after surgery were recorded.

Results:

From 2007 to 2017, total 1236 thyroidectomy were performed. The patients’ age ranged from 15 to 83-year-old with a mean age of patients was 44.5 ± 13.81 years old. Two hundred and twenty-nine patients (19%) were male and 1007 (81%) were female. We did not find any cases of tracheomalacia after thyroidectomy in our study population.

Conclusion:

Based on the results of this study, it seems that with the necessary precautions, the incidence of tracheomalacia can reach zero.

Esophageal Trachea, a Unique Foregut Malformation Requiring Multistage Surgical Reconstruction: Case Report

Abnormal connections between the esophagus and low respiratory tract can result from embryological defects in foregut development. Beyond well-known malformations, including tracheo-esophageal fistula and laryngo-tracheo-esophageal cleft, rarer anomalies have also been reported, including communicating bronchopulmonary foregut malformations and tracheal atresia. Herein, we describe a case of what we have called "esophageal trachea," which, to our knowledge, has yet to be reported. A full-term neonate was born in our institution presenting with a foregut malformation involving both the middle esophagus and the distal trachea, which were found to be longitudinally merged into a common segment, 3 cm in length, located just above the carina and consisted of esophageal tissue without cartilaginous rings. At birth, the esophagus and trachea were surgically separated via right thoracotomy, the common segment kept on the tracheal side only, creating a residual long-gap esophageal atresia. The resulting severe tracheomalacia was treated via simultaneous posterior splinting of such diseased segment using an autologous pericardium patch, as well as by anterior aortopexy. Terminal esophagostomy and gastrostomy were created at that stage due to the long distance between esophageal segments. Between ages 18 and 24 months, the patient underwent native esophageal reconstruction using a multistage traction-and-growth surgical strategy that combined Kimura extra-thoracic esophageal elongations at the upper esophagus and Foker external traction at the distal esophagus. Ten months after esophageal reconstruction, prolonged, refractory, and severe tracheomalacia was further treated via anterior external stenting using a semitubular ringed Gore-Tex® prosthesis, through simultaneous median sternotomy and tracheoscopy. Currently, 2 years after the last surgery, respiratory stabilization, and full oral feeding were stably achieved. Multidisciplinary management was crucial for assuring lifesaving procedures, correctly assessing anatomy, and planning for multiple sequential surgical approaches that aimed to restore long-term respiratory and digestive functions.

Tracheomalacia in bronchopulmonary dysplasia: Trachealis hyper-relaxant responses to S-nitrosoglutathione in a hyperoxic murine model

BACKGROUND

Bronchopulmonary dysplasia (BPD) with airway hyperreactivity is a long-term pulmonary complication of prematurity. The endogenous nonadrenergic, noncholinergic signaling molecule, S-nitrosoglutathione (GSNO) and its catabolism by GSNO reductase (GSNOR) modulate airway reactivity. Tracheomalacia is a major, underinvestigated complication of BPD. We studied trachealis, left main bronchus (LB), and intrapulmonary bronchiolar (IPB) relaxant responses to GSNO in a murine hyperoxic BPD model.

METHODS

Wild-type (WT) or GSNOR knockout (KO) newborn mice were raised in 60% (BPD) or 21% (control) oxygen during the first 3 weeks of life. After room air recovery, adult trachealis, LB, and IPB smooth muscle relaxant responses to GSNO (after methacholine preconstriction) were studied using wire myographs. Studies were repeated after GSNOR inhibitor (GSNORi) pretreatment and in KO mice.

RESULTS

GSNO relaxed all airway preparations. GSNO relaxed WT BPD trachealis substantially more than WT controls (P < .05). Pharmacologic or genetic ablation of GSNOR abolished the exaggerated BPD tracheal relaxation to GSNO and also augmented BPD IPB relaxation to GSNO. LB ring contractility was not significantly different between groups or conditions. Additionally, GSNORi treatment induced relaxation of WT IPBs but not trachealis or LB.

CONCLUSION

GSNO dramatically relaxed the trachealis in our BPD model, an effect paradoxically reversed by loss of GSNOR. Conversely, GSNOR inhibition augmented IBP relaxation. These data suggest that GSNOR inhibition could benefit both the BPD trachealis and distal airways, restoring relaxant responses to those of room air controls. Because therapeutic options are limited in this high-risk population, future studies of GSNOR inhibition are needed.

Respiratory Phenotypes for Preterm Infants, Children, and Adults: Bronchopulmonary Dysplasia and More

Ongoing advancements in neonatal care since the late 1980s have led to increased numbers of premature infants surviving well beyond the neonatal period. As a result of increased survival, many individuals born preterm manifest chronic respiratory symptoms throughout infancy, childhood, and adult life. The archetypical respiratory disease of prematurity, bronchopulmonary dysplasia, is the second most common chronic pediatric respiratory disease after asthma. However, there are several commonly held misconceptions. These misconceptions include that bronchopulmonary dysplasia is rare, that bronchopulmonary dysplasia resolves within the first few years of life, and that bronchopulmonary dysplasia does not impact respiratory health in adult life. This focused review describes a spectrum of respiratory conditions that individuals born prematurely may experience throughout their lifespan. Specifically, this review provides quantitative estimates of the number of individuals with alveolar, airway, and vascular phenotypes associated with bronchopulmonary dysplasia, as well as non-bronchopulmonary dysplasia respiratory phenotypes such as airway malacia, obstructive sleep apnea, and control of breathing issues. Furthermore, this review illustrates what is known about the potential for progression and/or lack of resolution of these respiratory phenotypes in childhood and adult life. Recognizing the spectrum of respiratory phenotypes associated with individuals born preterm and providing comprehensive and personalized care to these individuals may help to modulate adverse respiratory outcomes in later life.

Preclinical assessment of resorbable silk splints for the treatment of pediatric tracheomalacia

OBJECTIVE

Tracheomalacia is characterized by weakness of the tracheal wall resulting in dynamic airway collapse during respiration; severe cases often require surgical intervention. Off-label external splinting with degradable implants has been reported in humans; however, there remains a need to develop splints with tunable mechanical properties and degradation profiles for the pediatric population. The objective of this pilot study is to assess the safety and efficacy of silk fibroin-based splints in a clinically relevant preclinical model of tracheomalacia.

METHODS

Silk splints were evaluated in a surgically induced model of severe tracheomalacia in N = 3 New Zealand white rabbits for 17, 24, and 31 days. An image-based assay was developed to quantify the dynamic change in airway area during spontaneous respiration, and histopathology was used to study the surrounding tissue response.

RESULTS

The average change in area in the native trachea was 23% during spontaneous respiration; surgically induced tracheomalacia resulted in a significant increase to 86% (P < 0.001). The average change in airway area after splint placement was reduced at all terminal time points (17, 24, and 31 days postimplantation), indicating a clinical improvement, and was not statistically different than the native trachea. Histopathology showed a localized inflammatory reaction characterized by neutrophils, eosinophils, and mononuclear cells, with early signs suggestive of fibrosis at the splint and tissue interface.

CONCLUSION

This pilot study indicates that silk fibroin splints are well tolerated and efficacious in a rabbit model of severe tracheomalacia, with marked reduction in airway collapse following implantation and good tolerability over the studied time course.

LEVEL OF EVIDENCE

NA Laryngoscope, 129:2189-2194, 2019.

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.

3D-printed, externally-implanted, bioresorbable airway splints for severe tracheobronchomalacia

OBJECTIVES/HYPOTHESIS

To report the clinical safety and efficacy of three-dimensional (3D)-printed, patient-specific, bioresorbable airway splints in a cohort of critically ill children with severe tracheobronchomalacia.

STUDY DESIGN

Case series.

METHODS

From 2012 to 2018, 15 subjects received 29 splints on their trachea, right and/or left mainstem bronchi. The median age at implantation was 8 months (range, 3-25 months). Nine children were female. Five subjects had a history of extracorporeal membrane oxygenation (ECMO), and 11 required continuous sedation, six of whom required paralytics to maintain adequate ventilation. Thirteen were chronically hospitalized, unable to be discharged, and seven were hospitalized their entire lives. At the time of splint implantation, one subject required ECMO, one required positive airway pressure, and 13 subjects were tracheostomy and ventilator dependent, requiring a median positive end-expiratory pressure (PEEP) of 14 cm H₂ O (range, 6-20 cm H₂ 0). Outcomes collected included level of respiratory support, disposition, and splint-related complications.

RESULTS

At the time of discharge from our institution, at a median of 28 days postimplantation (range, 10-56 days), the subject on ECMO was weaned from extracorporeal support, and the subjects who were ventilated via tracheostomy had a median change in PEEP (discharge-baseline) of -2.5 cm H₂ O (range, -15 to 2 cm H₂ O, P = .022). At median follow-up of 8.5 months (range, 0.3-77 months), all but one of the 12 surviving subjects lives at home. Of the 11 survivors who were tracheostomy dependent preoperatively, one is decannulated, one uses a speaking valve, six use a ventilator exclusively at night, and three remain ventilator dependent.

CONCLUSIONS

This case series demonstrates the initial clinical efficacy of the 3D-printed bioresorbable airway splint device in a cohort of critically ill children with severe tracheobronchomalacia.

LEVEL OF EVIDENCE

4 Laryngoscope, 129:1763-1771, 2019.

Lung Microbiota and Pulmonary Inflammatory Cytokines Expression Vary in Children With Tracheomalacia and Adenoviral or Mycoplasma pneumoniae Pneumonia

Community-acquired pneumonia (CAP) is a worldwide infectious disease caused by bacteria, viruses, or a combination of these infectious agents. Mycoplasma pneumoniae is an atypical pneumonia pathogen that causes high morbidity and mortality in children, and adenovirus can lead to severe pneumonia. However, the etiology of different types of pneumonia is still unclear. In this study, we selected a total of 52 inpatients with M. pneumoniae pneumonia (MPP) (n = 21), adenovirus pneumonia (AVP) (n = 16), or tracheomalacia (n = 15) to serve as a disease control. Bronchoalveolar lavage fluid (BALF) samples that had been obtained for clinical use were analyzed. We compared the differences in microbiota and the expression of 10 inflammatory cytokines in samples between MPP, AVP, and tracheomalacia. We found that the bacterial diversity in MPP was lower than that in AVP and tracheomalacia. Mycoplasma, Streptococcus, and Pseudomonas were predominant in samples of MPP, AVP, and tracheomalacia, respectively. The expression levels of IL-6, IL-8, and IL-10 were significantly higher in inpatients with AVP compared to children hospitalized with tracheomalacia or MPP. The lung microbiota in MPP was remarkably correlated with IL-2, IL-4, IL-5, IL-6, TNF-α, and IL-1α expressions, while this was not found in tracheomalacia and AVP. Microbiota analysis identified a high load of multi-drug resistant Acinetobacter baumannii in the lung microbiota of several inpatients, which might be associated with the long hospitalization length and intra-group differences at the individual level. This study will help to understand the microbial etiology of tracheomalacia, AVP, and MPP and to identify effective therapies for these diseases.

Tracheomalacia and Tracheobronchomalacia in Pediatrics: An Overview of Evaluation, Medical Management, and Surgical Treatment

Tracheobronchomalacia (TBM) refers to airway collapse due to typically excessive posterior membrane intrusion and often associated with anterior cartilage compression. TBM occurs either in isolation or in association with other congenital or acquired conditions. Patients with TM typically present non-specific respiratory symptoms, ranging from noisy breathing with a typical barking cough to respiratory distress episodes to acute life-threatening events and recurrent and/or prolonged respiratory infections. There are no definitive standardized guidelines for the evaluation, diagnosis, and treatment of TBM; therefore, patients may be initially misdiagnosed and incorrectly treated. Although milder cases of TBM may become asymptomatic as the diameter of the airway enlarges with the child, in cases of severe TBM, more aggressive management is warranted. This article is an overview of the clinical presentation, evaluation, diagnosis, medical management, and surgical treatment options in pediatric tracheomalacia.

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

BACKGROUND/AIMS

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Technique, pitfalls, quality, radiation dose and findings of dynamic 4-dimensional computed tomography for airway imaging in infants and children

This retrospective review of 33 children's dynamic 4-dimensional (4-D) computed tomography (CT) images of the airways, performed using volume scanning on a 320-detector array without anaesthesia (free-breathing) and 1.4-s continuous scanning, was undertaken to report technique, pitfalls, quality, radiation doses and findings. Tracheobronchomalacia (airway diameter collapse >28%) was recorded. Age-matched routine chest CT scans and bronchograms acted as benchmarks for comparing effective dose. Pitfalls included failure to administer intravenous contrast, pull back endotracheal tubes and/or remove nasogastric tubes. Twenty-two studies (67%) were diagnostic. Motion artefact was present in 16 (48%). Mean effective dose: dynamic 4-D CT 1.0 mSv; routine CT chest, 1.0 mSv, and bronchograms, 1.4 mSv. Dynamic 4-D CT showed tracheobronchomalacia in 20 patients (61%) and cardiovascular abnormalities in 12 (36%). Fourteen children (70%) with tracheobronchomalacia were managed successfully by optimising conservative management, 5 (25%) underwent surgical interventions and 1 (5%) died from the presenting disorder.

Congenital tracheal malformations

Congenital malformations of the trachea include a variety of conditions that cause respiratory distress in neonates and infants. A number of anomalies are self-limiting while others are life-threatening and require immediate therapy. The prevalence of congenital airway malformations has been estimated to range between 0.2 and 1 in 10,000 live births. The most frequent congenital tracheal malformations are: tracheomalacia, congenital tracheal stenosis, laryngotracheal cleft and tracheal agenesis. The management of congenital tracheal malformations is complex and requires an individualized approach delivered by a multidiscipilinary team within centralized units with the necessary expertise.

Difficulty in tracheal extubation followed by tracheal collapse after balloon dilatation for tracheal stenosis therapy: A case report

RATIONALE

Tracheobronchomalacia (TBM) refers to the weakening trachea or the trachea loss of structural integrity of airway cartilaginous structures. It causes tracheal stenosis, resulting in significantly high rates of mortality. Bronchoplasty by high-pressure balloon dilation under general anesthesia is a simple but effective and safe method to treat tracheobronchial stenosis. However, recurrent postoperative dyspnea after extubation due to tracheal collapse is still a challenge for anesthetists.

PATIENT CONCERNS

A 52-year-old man weighing 72 kg was scheduled for balloon dilatation surgery under general anesthesia because of breathing difficulties caused by tracheal stenosis. His previous medical history included rheumatoid arthritis, obstructive sleep apnea syndrome (OSAS), chronic bronchitis and a history of tracheal intubation. Laryngeal computerized tomography confirmed the stenosis at the level of thyroid gland.

DIAGNOSIS

The tracheal collapse after balloon dilatation for tracheal stenosis therapy.

INTERVENTIONS

Postoperatively, the patient presented with more serious and repetitive symptoms of dyspnea after extubation when compared to that before treatment. So, we had to re-insert the laryngeal mask airway (LMA), and exclude some anesthesia-associated factors, such as laryngospasm, bronchospasm and so on. After a series of treatments, we ultimately found the cause in time (the airway collapsed), and succeeded in tracheal extubation after the stent was inserted.

OUTCOMES

The patient recovered well and reported high satisfaction with anesthesia management.

LESSONS

In such an emergency even, the anesthesiologist should take valuable treatments to ensure the patient's effective ventilation. If the anesthesia-related factors can be eliminated, tracheomalacia or airway collapse should be considered whenever dyspnea occurs in the patients who unexpectedly fail to be extubated.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Tracheobronchomalacia Is Associated with Increased Morbidity in Bronchopulmonary Dysplasia

RATIONALE

Tracheobronchomalacia is a common comorbidity in neonates with bronchopulmonary dysplasia. However, the effect of tracheobronchomalacia on the clinical course of bronchopulmonary dysplasia is not well-understood.

OBJECTIVE

We sought to assess the impact of tracheobronchomalacia on outcomes in neonates with bronchopulmonary dysplasia in a large, multi-center cohort.

METHODS

We preformed a cohort study of 974 neonates with bronchopulmonary dysplasia admitted to 27 neonatal intensive care units participating in the Children's Hospital Neonatal Database who had undergone bronchoscopy. In hospital morbidity for neonates with bronchopulmonary dysplasia and tracheobronchomalacia (N=353, 36.2%) was compared to those without tracheobronchomalacia (N=621, 63.8%) using mixed-effects multivariate regression.

RESULTS

Neonates with tracheobronchomalacia and bronchopulmonary dysplasia had more comorbidities, such as gastroesophageal reflux (OR=1.65, 95%CI 1.23- 2.29, P=0.001) and pneumonia (OR=1.68, 95%CI 1.21-2.33, P=0.002) and more commonly required surgeries such as tracheostomy (OR=1.55, 95%CI 1.15-2.11, P=0.005) and gastrostomy (OR=1.38, 95%CI 1.03-1.85, P=0.03) compared with those without tracheobronchomalacia. Neonates with tracheobronchomalacia were hospitalitized (118 ± 93 vs 105 ± 83 days, P=0.02) and ventilated (83.1 ± 91.1 vs 67.2 ± 71.9 days, P=0.003) longer than those without tracheobronchomalacia. Upon discharge, neonates with tracheobronchomalacia and BPD were more likely to be mechanically ventilated (OR=1.37, 95CI 1.01-1.87 P=0.045) and possibly less likely to receive oral nutrition (OR=0.69, 95%CI 0.47-1.01, P=0.058).

CONCLUSIONS

Tracheobronchomalacia is common in neonates with bronchopulmonary dysplasia who undergo bronchoscopy and is associated with longer and more complicated hospitalizations.

Computational modeling of airway instability and collapse in tracheomalacia

Background

Tracheomalacia (TM) is a condition of excessive tracheal collapse during exhalation. Both acquired and congenital forms of TM are believed to result from morphological changes in cartilaginous, fibrous and/or smooth muscle tissues reducing airway mechanical properties to a degree that precipitates collapse. However, neither the specific amount of mechanical property reduction nor the malacic segment lengths leading to life threatening airway collapse in TM are known. Furthermore, the specific mechanism of collapse is still debated.

Methods

Computational nonlinear finite element models were developed to determine the effect of malacic segment length, tracheal diameter, and reduction in tissue nonlinear elastic properties on the risk for and mechanism of airway collapse. Cartilage, fibrous tissue, and smooth muscle nonlinear elastic properties were fit to experimental data from preterm lambs from the literature. These elastic properties were systematically reduced in the model to simulate TM.

Results

An intriguing finding was that sudden mechanical instability leading to complete airway collapse occurred in airways when even a 1 cm segment of cartilage and fibrous tissue properties had a critical reduction in material properties. In general, increased tracheal diameter, increased malacic segment length coupled with decreased nonlinear anterior cartilage/fibrous tissue nonlinear mechanical properties increased the risk of sudden airway collapse from snap through instability.

Conclusion

Modeling results support snap through instability as the mechanism for life threatening tracheomalacia specifically when cartilage ring nonlinear properties are reduced to a range between fibrous tissue nonlinear elastic properties (for larger diameter airways > 10 mm) to mucosa properties (for smaller diameter airways < 6 mm). Although reducing posterior tracheal smooth muscle properties to mucosa properties decreased exhalation area, no sudden instability leading to collapse was seen in these models.

Airway smooth muscle dysfunction in Pompe (Gaa-/- ) mice

Pompe disease is an autosomal recessive disorder caused by a deficiency of acid α-glucosidase (GAA), an enzyme responsible for hydrolyzing lysosomal glycogen. Deficiency of GAA leads to systemic glycogen accumulation in the lysosomes of skeletal muscle, motor neurons, and smooth muscle. Skeletal muscle and motor neuron pathology are known to contribute to respiratory insufficiency in Pompe disease, but the role of airway pathology has not been evaluated. Here we propose that GAA enzyme deficiency disrupts the function of the trachea and bronchi and this lower airway pathology contributes to respiratory insufficiency in Pompe disease. Using an established mouse model of Pompe disease, the Gaa^-/- mouse, we compared histology, pulmonary mechanics, airway smooth muscle (ASM) function, and calcium signaling between Gaa^-/- and age-matched wild-type (WT) mice. Lysosomal glycogen accumulation was observed in the smooth muscle of both the bronchi and the trachea in Gaa^-/- but not WT mice. Furthermore, Gaa^-/- mice had hyporesponsive airway resistance and bronchial ring contraction to the bronchoconstrictive agents methacholine (MCh) and potassium chloride (KCl) and to a bronchodilator (albuterol). Finally, calcium signaling during bronchiolar smooth muscle contraction was impaired in Gaa^-/- mice indicating impaired extracellular calcium influx. We conclude that GAA enzyme deficiency leads to glycogen accumulation in the trachea and bronchi and impairs the ability of lower ASM to regulate calcium and respond appropriately to bronchodilator or constrictors. Accordingly, ASM dysfunction may contribute to respiratory impairments in Pompe disease.

Cartilage rings contribute to the proper embryonic tracheal epithelial differentiation, metabolism, and expression of inflammatory genes

The signaling cross talk between the tracheal mesenchyme and epithelium has not been researched extensively, leaving a substantial gap of knowledge in the mechanisms dictating embryonic development of the proximal airways by the adjacent mesenchyme. Recently, we reported that embryos lacking mesenchymal expression of Sox9 did not develop tracheal cartilage rings and showed aberrant differentiation of the tracheal epithelium. Here, we propose that tracheal cartilage provides local inductive signals responsible for the proper differentiation, metabolism, and inflammatory status regulation of the tracheal epithelium. The tracheal epithelium of mesenchyme-specific Sox9^Δ/Δ mutant embryos showed altered mRNA expression of various epithelial markers such as Pb1fa1, surfactant protein B (Sftpb), secretoglobulin, family 1A, member 1 (Scgb1a1), and trefoil factor 1 (Tff1). In vitro tracheal epithelial cell cultures confirmed that tracheal chondrocytes secrete factors that inhibit club cell differentiation. Whole gene expression profiling and ingenuity pathway analysis showed that the tumor necrosis factor-α (TNF-α), interferon-γ (IFN-γ), and transforming growth factor-β (TGF-β) signaling pathways were significantly altered in the Sox9 mutant trachea. TNF-α and IFN-γ interfered with the differentiation of tracheal epithelial progenitor cells into mature epithelial cell types in vitro. Mesenchymal knockout of Tgf-β1 in vivo resulted in altered differentiation of the tracheal epithelium. Finally, mitochondrial enzymes involved in fat and glycogen metabolism, cytochrome c oxidase subunit VIIIb (Cox8b) and cytochrome c oxidase subunit VIIa polypeptide 1 (Cox7a1), were strongly upregulated in the Sox9 mutant trachea, resulting in increases in the number and size of glycogen storage vacuoles. Our results support a role for tracheal cartilage in modulation of the differentiation and metabolism and the expression of inflammatory-related genes in the tracheal epithelium by feeding into the TNF-α, IFN-γ, and TGF-β signaling pathways.

Comparing changing neurally adjusted ventilatory assist (NAVA) levels in intubated and recently extubated neonates

OBJECTIVE

Neurally adjusted ventilatory assist (NAVA) is a mode of mechanical ventilation that delivers ventilatory support in synchrony to the patient's respiratory needs using NAVA level, a proportionality constant that converts the electrical activity of the diaphragm (Edi) into a peak pressure (PIP). Recent published studies suggest that neonates can control the delivered ventilatory support through neural feedback. Systematically increasing the NAVA level initially increases the PIP while maintaining a constant Edi until an inflection point or breakpoint (BrP) is reached, at which time the PIP plateaus and the Edi signal decreases. This study was performed to establish if there is a correlation of pre- and post-extubation BrP in premature neonates.

STUDY DESIGN

NAVA level was increased by 0.5 cm H₂O mcV^-1 every 3 min from 0.1 to 3.0 cm H₂O mcV^-1. PIP and Edi Peak and Minimum were recorded.

STATISTICS

PIP and phasic Edi (Edi peak-Edi min) were averaged for each NAVA level, plotted on a graph, and the BrP was determined by visual inspection of the inflection point for PIP. The data from the studies were then combined by averaging each variable at the BrP and for each change in NAVA level above and below the BrP.

RESULTS

Fifteen infants were studied for paired titration studies. PIP increased until the BrP was reached and then plateaued during both the intubated and extubated titration studies. Edi decreased after the BrP was reached during the titration studies. The BrP increased when patients were extubated from NAVA to noninvasive (NIV) NAVA. As the NAVA level rose above the BrP, PIP plateaued at a higher level and Edi decreased less during the NIV NAVA titration study.

CONCLUSIONS

Neonates demonstrated an increase in BrP, higher PIP and Edi when extubated from NAVA to NIV NAVA. This is most likely owing to the inefficiencies of NIV ventilation and suggests that neonates require a higher NAVA level when transitioning from NAVA to NIV NAVA.