Tracheomalacia and bronchomalacia in children: pathophysiology, assessment, treatment and anaesthesia management

The anesthetic management of a child with ohtahara syndrome and severe stridor: a case report

BACKGROUND

Ohtahara syndrome is a progressive developmental and epileptic encephalopathy that manifests in the early infantile period. This rare condition is characterized by intractable seizures, psychomotor retardation, and poor prognosis. To date, there are a handful of case reports regarding the anesthetic management of children with Ohtahara syndrome. However, limited reports exist of patients with Ohtahara syndrome who present with difficult airways. This report describes our airway findings and general anesthetic management of a pediatric patient with Ohtahara syndrome undergoing diagnostic bronchoscopy for severe inspiratory stridor.

CASE PRESENTATION

A 14-month-old, 9 kg, male patient with Ohtahara syndrome presented with a year-long history of severe inspiratory stridor and was scheduled for bronchoscopy with lavage. On exam, the patient had noisy breathing, was non-verbal with developmental delay, and had poor head control with significant central hypotonia. The patient was induced with ketamine and general anesthesia was maintained with propofol. Bronchoscopic evaluation was completed uneventfully and revealed a diagnosis of laryngotracheomalacia. The patient's breathing was maintained spontaneously throughout the procedure and no seizures were noted. In the post anesthesia care unit, the patient's respiratory and cardiovascular function were stable.

CONCLUSIONS

This report documents the unusual finding of severe inspiratory stridor in a 14-month-old child diagnosed with Ohtahara syndrome and our anesthetic management during their diagnostic bronchoscopy. Currently, documentation of complex airway pathology present in patients with Ohtahara syndrome is limited and should be further evaluated. This will assist pediatric anesthesiologists as these patients may require careful preoperative assessment, thoughtful airway management, and surgical alternatives on standby.

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.

Dynamic PEEP Study: A Non-invasive Diagnostic Exam to Assess for Effective PEEP in Children with Severe BPD

OBJECTIVE

Tracheobronchomalacia (TBM) is common in neonates with bronchopulmonary dysplasia (BPD) and is associated with higher morbidity. This study evaluates the value of a CT protocol to assess the degree of TBM and gauge the adequacy of prescribed PEEP.

STUDY DESIGN

Four infants with severe BPD on invasive mechanical ventilation underwent a chest CT protocol, including limited reduced-dose expiratory scans with varying PEEP levels.

RESULTS

Baseline PEEP was adjusted in all subjects after performing the Dynamic PEEP CT. In two infants, the PEEP was increased due to significant TBM and in the other two without signs of TBM PEEP was decreased. The clinical course improved in all patients after adjusting PEEP.

CONCLUSION

A "Dynamic PEEP" study may be reliable and non-invasive imaging modality for the evaluation of adequate ventilator settings in infants with severe BPD who are not optimal candidates for bronchoscopy.

Quantifying Upper Aerodigestive Sequelae in Esophageal Atresia/Tracheoesophageal Fistula Neonates

OBJECTIVES

We examined rates of upper aerodigestive tract (UADT) procedures in a multi-institutional cohort of neonates with esophageal atresia/tracheoesophageal fistula (EA/TEF) to estimate secondary UADT pathology.

METHODS

A retrospective cohort study was performed using a previously-validated population of patients with EA/TEF within the Pediatric Health Information System (PHIS) between 2007 and 2015. ICD-9/10-CM codes for aerodigestive procedures were examined from 2007 to 2020: 1) diagnostic direct laryngoscopy and/or bronchoscopy (DLB), 2) DLB with intervention, 3) tracheostomy, 4) gastrostomy, 5) fundoplication, 6) aortopexy, 7) laryngotracheoplasty, and 8) esophageal dilation. Associations between procedures and demographics, length of gestation, and weight were estimated using generalized linear mixed models.

RESULTS

We identified 2,509 patients with EA/TEF from 47 hospitals, 56.7% male and 43.3% female. Median length of stay for the first admission was 24 days (interquartile range: 12-55). Of these patients, 1,943 (77.4%) had at least one aerodigestive procedure within 14 admissions. Specifically, 1,635 (65.2%) underwent diagnostic DLB, 85 (3.4%) DLB with intervention, 167 (6.7%) tracheostomy, 1,043 (41.2%) gastrostomy, 211 (11.0%) fundoplication, 52 (2.1%) aortopexy, 161 (6.4%) laryngotracheoplasty, and 207 (8.3%) esophageal dilation. Preterm gestation increased odds of tracheostomy (adjusted odds ratio (OR) 2.4, 95% confidence interval (CI) 1.5-3.7), gastrostomy (OR 2.1, CI 1.7-2.7), fundoplication (OR 1.7, CI 1.1-2.4), aortopexy (OR 5.8, CI 2.1-16.1), and esophageal dilation (OR 2.0, CI 1.4-3.0). Very low birth weight (<1,500 g) increased odds of gastrostomy (OR 2.5, CI 1.6-3.8).

CONCLUSION

Patients with EA/TEF frequently have aerodigestive sequelae. This work helps quantify aerodigestive needs in neonates with EA/TEF, suggesting early otolaryngology evaluation in their care.

LEVEL OF EVIDENCE

3 Laryngoscope, 2021.

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.

Respiratory subtype of relapsing polychondritis frequently presents as difficult asthma: a descriptive study of respiratory involvement in relapsing polychondritis with 13 patients from a single UK centre

Introduction

Relapsing polychondritis is a rare multisystem vasculitis characterised by recurrent cartilage inflammation. Respiratory involvement, of which tracheobronchomalacia (TBM) is the commonest form, is difficult to treat and is linked to increased mortality. We describe 13 patients with respiratory involvement.

Methods

This is a retrospective study of all the patients with relapsing polychondritis at University Hospitals Coventry and Warwickshire NHS Trust (UHCW), a secondary care provider for ∼500 000. Only patients with respiratory involvement were included in this study.

Results

We identified 13 patients who fulfilled the inclusion criteria. Most patients were identified from the “difficult asthma” clinic. TBM was seen in 11 patients, whilst two patients had pleural effusions which resolved with immunosuppression and one patient had small airways disease. Computed tomography scans (inspiratory and expiratory) and bronchoscopy findings were useful in diagnosing TBM. Pulmonary function testing revealed significant expiratory flow abnormalities. All patients were treated with corticosteroids/disease-modifying anti-rheumatic drugs (DMARDs) and some were given cyclophosphamide or biological agents, although the response to cyclophosphamide (1 out of 4) or biologicals (2 out of 4) was modest in this cohort. Ambulatory continuous positive airway pressure ventilation was successful in four patients.

Conclusions

Relapsing polychondritis may be overlooked in “difficult asthma” clinics with patients having TBM (not asthma) and other features of relapsing polychondritis. Awareness of this condition is crucial to enable early diagnosis and interventions to reduce the risk of life-threatening airway collapse. A number of patients respond well to DMARDs and are able to minimise corticosteroid use.

Tracheobronchomalacia can present as “difficult asthma” and can be associated with relapsing polychondritis. Optimal management of relapsing polychondritis is through medical treatments and support for the damaged airway through positive airway pressure.https://bit.ly/2JGoq23

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.

Care recommendations for the respiratory complications of esophageal atresia-tracheoesophageal fistula

Tracheoesophageal fistula (TEF) with esophageal atresia (EA) is a common congenital anomaly that is associated with significant respiratory morbidity throughout life. The objective of this document is to provide a framework for the diagnosis and management of the respiratory complications that are associated with the condition. As there are no randomized controlled studies on the subject, a group of experts used a modification of the Rand Appropriateness Method to describe the various aspects of the condition in terms of their relative importance, and to rate the available diagnostic methods and therapeutic interventions on the basis of their appropriateness and necessity. Specific recommendations were formulated and reported as Level A, B, and C based on whether they were based on "strong", "moderate" or "weak" agreement. The tracheomalacia that exists in the site of the fistula was considered the main abnormality that predisposes to all other respiratory complications due to airway collapse and impaired clearance of secretions. Aspiration due to impaired airway protection reflexes is the main underlying contributing mechanism. Flexible bronchoscopy is the main diagnostic modality, aided by imaging modalities, especially CT scans of the chest. Noninvasive positive airway pressure support, surgical techniques such as tracheopexy and rarely tracheostomy are required for the management of severe tracheomalacia. Regular long-term follow-up by a multidisciplinary team was considered imperative. Specific templates outlining the elements of the clinical respiratory evaluation according to the patients' age were also developed.

Absorbable Microplate Externally Suspending Bronchomalacia in Congenital Heart Disease Infant

To evaluate the feasibility and efficacy of external suspension with absorbable poly-l-lactic acid material shaping microplates for infants with severe bronchomalacia and congenital heart disease. From November 2017 to January 2019, 11 continual patients with severe bronchomalacia and congenital heart disease underwent bronchial membrane external suspension together with cardiovascular surgery. An absorbable plate made with poly-l-lactic acid material was used as the shaping fixation material in all patients. Data included the details of the operation, and clinical results were collected. The mean age was 1.2 ± 1.0 years, and the mean weight was 7.7 ± 2.9 kg. The patients with cardiac malformations were operated on under low-temperature cardiopulmonary bypass (CPB) through median sternotomy. There were no in-hospital deaths. The CPB time, mechanical ventilation time, and length of intensive care unit stay were 123.9 ± 36.9 min, 20.7 ± 19.4 h, and 71.6 ± 54.9 h, respectively. Two patients underwent surgery through a left posterolateral incision without CPB. One was a double aortic arch repair, and the other was only bronchial membrane external suspension with prior IAA repair. No patients needed ECMO support. The mean follow-up time was 12.1 ± 5.6 months, and no patients were lost to follow-up. No cases of late death were noted, and no patients needed reoperation. According to the CT scans, no patients had bronchial restenosis. External bronchial membrane suspension with an absorbable poly-l-lactic acid material shaping plate, which had better histocompatibility, for infants with severe bronchomalacia and congenital heart disease was a safe and feasible procedure.

3D printing for tissue engineering in otolaryngology

Airway and other head and neck disorders affect hundreds of thousands of patients each year and most require surgical intervention. Among these, congenital deformity that affects newborns is particularly serious and can be life-threatening. In these cases, reconstructive surgery is resolutive but bears significant limitations, including the donor site morbidity and limited available tissue. In this context, tissue engineering represents a promising alternative approach for the surgical treatment of otolaryngologic disorders. In particular, 3D printing coupled with advanced imaging technologies offers the unique opportunity to reproduce the complex anatomy of native ear, nose, and throat, with its import in terms of functionality as well as aesthetics and the associated patient well-being. In this review, we provide a general overview of the main ear, nose and throat disorders and focus on the most recent scientific literature on 3D printing and bioprinting for their treatment.

Dynamic Tracheobronchial Compression in Steep Trendelenburg Position With Pneumoperitoneum for Robotic-Assisted Cystectomy: A Case Report

Tracheobronchomalacia is a weakness of the trachea and bronchi due to abnormal cartilage and muscular support leading to airway obstruction. We report a case of an adult former smoker without pulmonary symptoms who underwent robotic-assisted laparoscopic cystectomy in the steep Trendelenburg position. After repeated episodes of hypoxemia, bronchoscopic examination revealed collapse of the distal trachea and bronchi, supporting a diagnosis of tracheobronchomalacia. Tracheomalacia is an underdiagnosed condition in patients with a smoking history and may mimic other obstructive diseases. The anesthesiologist should remain vigilant to the possibility of airway collapse in former smokers, specifically in cases of increased intrathoracic pressure.

ERS statement on tracheomalacia and bronchomalacia in children

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

Pediatric tracheomalacia and the perioperative anesthetic management of thoracoscopic posterior tracheopexy

Tracheomalacia is a broad term used to describe an abnormally compliant trachea that can lead to exaggerated collapse and obstruction with expiration. We describe the perioperative management of a complex pediatric patient undergoing a posterior tracheopexy which is a relatively new surgical treatment, with a novel surgical approach-thoracoscopy. This procedure has competing surgical and anesthetic needs and presents unique challenges to the physicians involved in caring for these patients. We also review the current literature on pediatric tracheomalacia and examine the newest treatment options to highlight the potential anesthetic challenges and pitfalls associated with management.

Fluoroscopic characteristics of tracheal collapse and cervical lung herniation in dogs: 222 cases (2012-2015)

This retrospective study included 222 dogs suspected to have tracheal collapse (TC) and examined between 1 January 2012 and 31 December 2015. Fluoroscopic and radiographic images and medical records were evaluated to investigate the fluoroscopic characteristics of TC and cervical lung herniation (CLH), and to determine their relationships to various influencing. Grade of TC, existence of tracheal kinking, location of CLH (right or left side), and grade of CLH were evaluated fluoroscopically. One hundred ninety-nine dogs (89.6%) were diagnosed with TC. Presence of TC was not associated with the patients' cough history; however, CLH was positively correlated with cough history (odds ratio [OR], 2.896; 95% confidence interval [CI], 1.556 to 5.390) and was affected by tracheal kinking (OR, 3.841; 95% CI, 1.884 to 7.831). Chronic cough was not related with CLH. Since TC can be observed in patients without a history of cough, presence of TC should be ruled out by using physical examination and diagnostic imaging. Although CLH is associated with a history of cough, it is a common appearance in dogs, and transient coughing can elicit CLH in patients without a history of cough.

Tracheobronchial stenting for airway malacia

Tracheobronchomalacia is a rare but clinically troublesome condition in paediatrics. The softening of the major airways - which can include some or all of the tracheobronchial tree can lead to symptoms ranging from the minor (harsh barking cough, recurrent chest infections) to severe respiratory difficulties including prolonged ventilator support and 'near death attacks'. The causes are broadly divided into intrinsic softening of the airway wall which is considered a primary defect (e.g. syndromes; post tracheo-oesophageal fistula repair; extreme prematurity) or secondary malacia due to external compression from vascular structures or cardiac components. These secondary changes can persist even when the external compression is relieved, for example, following the repair of a pulmonary artery sling or double aortic arch. For children with severe clinical symptoms attributed to malacia, consideration is given to possible surgical remedies such as an aortopexy for short limited areas of malacia, or long term positive pressure support with CPAP either by non invasive or tracheostomy interface. More recently the role of stenting in children is receiving attention, especially with the development of newer techniques such as bioabsorbable stents which buy time for a natural history of improvement in the malacia to occur. This paper reviews the stents available and discusses the pros and cons of stenting in paediatric airway malacia.

Laryngomalacia, Tracheomalacia and Bronchomalacia

Airway malacia can occur in the larynx (larygomalacia), trachea (tracheomalacia), or bronchi (bronchomalacia). As a group these are the most common congenital abnormalities of the pediatric airway and are characterized by increased airway compliance, resulting in excessive dynamic collapse during the respiratory cycle. While a diagnosis can be suspected based on clinical history and physical examination, definitive evaluation is based of nasopharyngolaryngoscopy and/or bronchoscopy. Observation and conservative management are typically all that are required. However, surgical intervention can be necessary in the most severe cases, and can result in significant improvement in symptoms.

Mechanical cause for acute left lung atelectasis after neonatal aortic arch repair with arterial switch operation: Conservative management

Respiratory complications due to mechanical obstruction of the airways can occur following pediatric cardiac surgery. Clinically significant intrathoracic vascular compression of the airway can occur when extensive dissection and mobilization of arch and neck vessels is involved as in repair of interrupted aortic arch. This case report describes a neonate who underwent interrupted aortic arch repair along with an arterial switch operation and developed a left lung collapse immediately after tracheal extubation. Fiber-optic bronchoscopy revealed vascular compression as the real culprit. The child was successfully managed conservatively.

Use of a biodegradable, oversized stent in a child with tracheomalacia secondary to vascular external compression

We describe the implantation of an absorbable, custom-made stent of polydioxanone to treat tracheomalacia in a 5-month-old patient with extrinsic compression by a double aortic arch. The use of an absorbable, oversized stent treated the tracheal collapse caused by vascular compression, avoided removal procedures, and allowed the infant's growth. The use of an oversized stent prevented stent migration and gave minimal problems of granulation.

Perspectives on neonatal and infant tracheostomy

Neonates and infants may need a tracheostomy for many different reasons, ranging from airway obstruction to a requirement for long term mechanical ventilator support. Here, we present the pathophysiology of the many congenital and acquired conditions that might be managed with a tracheostomy. Decisions about tracheostomy demand consideration of not only the benefits, but also the potential side-effects, which may differ in the short and long term and may be attributable to underlying conditions as well as the tracheostomy. Evaluation of potential advantages of tracheostomy will influence decisions about optimal timing. In many cases, an infant may 'graduate' from dependence on a tracheostomy and resume a natural airway, although some will require reconstructive airway surgery.

Bacterial sensitivity assessment of multifunctional polymeric coatings for airway stents

Current interventional technology for pediatric airway obstruction consists of cardiovascular stents and silicon tubes. These devices are composed of permanent materials that have limitations in biocompatibility and mechanical properties that make them controversial for used in pediatrics. Bioresorbable stents offer a temporary intervention that dissolves in the body over time and can serve as a platform for local drug delivery. Here we investigate a novel approach to use an antibiotic, ciprofloxacin, as a polymerization initiator to synthesize poly(ciprofloxacin fumaric acid) (PCFA) and then a second polymer using gadodiamide as an initiator to synthesize poly(gadodiamide ciprofloxacin fumaric acid) (PGCFA). Polymer structure, degradation, thermal properties, and rheological behavior were analyzed. Ciprofloxacin released was determined and polymer degradation extracts were used in bacterial sensitivity assessments with four common airway pathogens. PCFA and PGCFA polymers and drug release properties were compared to our previously published polymer poly(fumaric acid) (PFA). These novel polymers enable new possibilities as coatings for bioresorbable biomedical applications that require antibiotic resistance and imaging capabilities. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 2153-2161, 2017.

Effect of cell seeding on neotissue formation in a tissue engineered trachea

BACKGROUND

Surgical management of long segment tracheal disease is limited by a paucity of donor tissue and poor performance of synthetic materials. A potential solution is the development of a tissue-engineered tracheal graft (TETG) which promises an autologous airway conduit with growth capacity.

METHODS

We created a TETG by vacuum seeding bone marrow-derived mononuclear cells (BM-MNCs) on a polymeric nanofiber scaffold. First, we evaluated the role of scaffold porosity on cell seeding efficiency in vitro. We then determined the effect of cell seeding on graft performance in vivo using an ovine model.

RESULTS

Seeding efficiency of normal porosity (NP) grafts was significantly increased when compared to high porosity (HP) grafts (NP: 360.3 ± 69.19 × 10(3) cells/mm(2); HP: 133.7 ± 22.73 × 10(3) cells/mm(2); p<0.004). Lambs received unseeded (n=2) or seeded (n=3) NP scaffolds as tracheal interposition grafts for 6 weeks. Three animals were terminated early owing to respiratory complications (n=2 unseeded, n=1 seeded). Seeded TETG explants demonstrated wound healing, epithelial migration, and delayed stenosis when compared to their unseeded counterparts.

CONCLUSION

Vacuum seeding BM-MNCs on nanofiber scaffolds for immediate implantation as tracheal interposition grafts is a viable approach to generate TETGs, but further preclinical research is warranted before advocating this technology for clinical application.

Stent implantation into the tracheo-bronchial system in rabbits: histopathologic sequelae in bare metal vs. drug-eluting stents

Background

Stent implantation into the tracheo-bronchial system may be life-saving in selected pediatric patients with otherwise intractable stenosis of the upper airways. Following implantation, significant tissue proliferation may occur, requiring re-interventions. We sought to evaluate the effect of immunosuppressive coating of the stents on the extent of tissue proliferation in an animal model.

Methods

Bare metal and sirolimus-coated stents (Bx Sonic and Cypher Select, Johnson & Johnson, Cordis) were implanted into non-stenotic lower airways of New Zealand white rabbits (weight 3.1 to 4.8 kg). Three stents with sirolimus coating and six bare metal stents could be analyzed by means of histology and immunohistochemistry 12 months after implantation.

Results

On a macroscopic evaluation, all stents were partially covered with a considerable amount of whitish tissue. Histologically, these proliferations contained fiber-rich connective tissue and some fibromuscular cells without significant differences between both stent types. The superficial tissue layer was formed by typical respiratory epithelium and polygonal cells. Abundant lymphocyte infiltrations and moderate granulocyte infiltrations were found in both groups correspondingly, whereas foreign-body reaction was more pronounced around sirolimus-eluting stents.

Conclusions

After stent implantation in the tracheo-bronchial system of rabbits, we found tissue reactions comparable to those seen after stent implantation into the vascular system. There was no difference between coated and uncoated stents with regard to quality and quantity of tissue proliferation. We found, however, a significantly different inflammatory reaction with a more pronounced foreign-body reaction in sirolimus-coated stents. In our small series, drug-eluting stents did not exhibit any benefit over bare metal stents in an experimental setting.

A MALDI-MSI Approach to the Characterization of Radiation-Induced Lung Injury and Medical Countermeasure Development

Radiation-induced lung injury is highly complex and characterized by multiple pathologies, which occur over time and sporadically throughout the lung. This complexity makes biomarker investigations and medical countermeasure screenings challenging. Matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) has the ability to resolve differences spatially in molecular profiles within the lung following radiation exposure and can aid in biomarker identification and pharmaceutical efficacy investigations. MALDI-MSI was applied to the investigation of a whole-thorax lung irradiation model in non-human primates (NHP) for lipidomic analysis and medical countermeasure distribution.

Airway malacia in children with achondroplasia

This study was undertaken to assess the frequency of airway malacia in infants and young children with achondroplasia, a population well known to be at risk for a variety of respiratory problems. We also wished to evaluate what, if any, contribution airway malacia makes to the complex respiratory issues that may be present in those with achondroplasia. Retrospective chart review of all infants and young children with achondroplasia who were assessed through the Midwest Regional Bone Dysplasia Clinics from 1985 through 2012 (n = 236) was completed. Records of comprehensive clinical examinations, polysomnographic assessments, and airway visualization were reviewed and abstracted using a data collection form. Analyses were completed comparing the group with and those without evidence for airway malacia. Thirteen of 236 patients (5.5%) were found to have airway malacia. Most of those affected had lower airway involvement (9/13). The presence of airway malacia was correlated with an increased occurrence of obstructive sleep apnea as well as need for oxygen supplementation, airway surgeries and tracheostomy placement. Although estimates of the frequency of airway malacia in the general population are limited, its frequency in children with achondroplasia appears to be much higher than any published general population estimate. The presence of airway malacia appears to confound other breathing abnormalities in this population and results in the need for more invasive airway treatments.

Establishment of smooth muscle and cartilage juxtaposition in the developing mouse upper airways

In the trachea and bronchi of the mouse, airway smooth muscle (SM) and cartilage are localized to complementary domains surrounding the airway epithelium. Proper juxtaposition of these tissues ensures a balance of elasticity and rigidity that is critical for effective air passage. It is unknown how this tissue complementation is established during development. Here we dissect the developmental relationship between these tissues by genetically disrupting SM formation (through Srf inactivation) or cartilage formation (through Sox9 inactivation) and assessing the impact on the remaining lineage. We found that, in the trachea and main bronchi, loss of SM or cartilage resulted in an increase in cell number of the remaining lineage, namely the cartilage or SM, respectively. However, only in the main bronchi, but not in the trachea, did the loss of SM or cartilage lead to a circumferential expansion of the remaining cartilage or SM domain, respectively. In addition to SM defects, cartilage-deficient tracheas displayed epithelial phenotypes, including decreased basal cell number, precocious club cell differentiation, and increased secretoglobin expression. These findings together delineate the mechanisms through which a cell-autonomous disruption of one structural tissue can have widespread consequences on upper airway function.

Interventions for primary (intrinsic) tracheomalacia in children

BACKGROUND

Tracheomalacia, a disorder of the large airways where the trachea is deformed or malformed during respiration, is commonly seen in tertiary paediatric practice. It is associated with a wide spectrum of respiratory symptoms from life-threatening recurrent apnoea to common respiratory symptoms such as chronic cough and wheeze. Current practice following diagnosis of tracheomalacia includes medical approaches aimed at reducing associated symptoms of tracheomalacia, ventilation modalities of continuous positive airway pressure (CPAP) and bi-level positive airway pressure (BiPAP), and surgical approaches aimed at improving the calibre of the airway (airway stenting, aortopexy, tracheopexy).

OBJECTIVES

To evaluate the efficacy of medical and surgical therapies for children with intrinsic (primary) tracheomalacia.

SEARCH METHODS

The Cochrane Airways Group searched the Cochrane Central Register of Controlled Trials (CENTRAL), the Cochrane Airways Group's Specialised Register, MEDLINE and EMBASE databases. The Cochrane Airways Group performed the latest searches in March 2012.

SELECTION CRITERIA

All randomised controlled trials (RCTs) of therapies related to symptoms associated with primary or intrinsic tracheomalacia.

DATA COLLECTION AND ANALYSIS

Two reviewers extracted data from the included study independently and resolved disagreements by consensus.

MAIN RESULTS

We included one RCT that compared nebulised recombinant human deoxyribonuclease (rhDNase) with placebo in 40 children with airway malacia and a respiratory tract infection. We assessed it to be a RCT with overall low risk of bias. Data analysed in this review showed that there was no significant difference between groups for the primary outcome of proportion cough-free at two weeks (odds ratio (OR) 1.38; 95% confidence interval (CI) 0.37 to 5.14). However, the mean change in night time cough diary scores significantly favoured the placebo group (mean difference (MD) 1.00; 95% CI 0.17 to 1.83, P = 0.02). The mean change in daytime cough diary scores from baseline was also better in the placebo group compared to those on nebulised rhDNase, but the difference between groups was not statistically significant (MD 0.70; 95% CI -0.19 to 1.59). Other outcomes (dyspnoea, and difficulty in expectorating sputum scores, and lung function tests at two weeks also favoured placebo over nebulised rhDNase but did not reach levels of significance.

AUTHORS' CONCLUSIONS

There is currently an absence of evidence to support any of the therapies currently utilised for management of intrinsic tracheomalacia. It remains inconclusive whether the use of nebulised rhDNase in children with airway malacia and a respiratory tract infection worsens recovery. It is unlikely that any RCT on surgically based management will ever be available for children with severe life-threatening illness associated with tracheomalacia. For those with less severe disease, RCTs on interventions such as antibiotics and chest physiotherapy are clearly needed. Outcomes of these RCTs should include measurements of the trachea and physiological outcomes in addition to clinical outcomes.

Congenital absence of cartilaginous tracheal rings associated with esophageal atresia and trifurcated carina: a novel anomaly?

Tracheomalacia associated with esophageal atresia (EA) is a well-known condition. However, complete absence of tracheal rings (TRs) is extremely rare. Our aim is to describe a novel triad of conditions and to discuss the best treatment. An expremature male operated for EA presented with severe respiratory distress. The diagnosis of absent cartilage rings, suspected on bronchoscopy, was confirmed by optical coherence tomography. The absence of TRs was localized to a short tracheal segment, and the carina trifurcated into right upper lobe, right intermediate, and left main bronchus. The patient was treated with resection and anastomosis with a completely satisfactory course. Absence of TRs was previously reported by us in 2 other cases, both with associated EA and trifurcation of the carina. One child was treated with tracheostomy and the other with a stent, but the outcome was far from optimal. The patient with tracheostomy eventually underwent resection and anastomosis with tracheostomy closure. Congenital absence of TRs is extremely rare. Although localized, it is responsible for severe symptoms owing to complete tracheal collapse and may be misdiagnosed as tracheomalacia. In our experience, it has been associated with EA and trifurcated carina. Our limited experience suggests resection of the abnormal segment and tracheal anastomosis as the best treatment.

A comparison of fluoroscopic airway screening with flexible bronchoscopy for diagnosing tracheomalacia

BACKGROUND

Flexible bronchoscopy (FB) is the gold standard method of diagnosing tracheomalacia but it is not always feasible in settings with limited resources. Fluoroscopy is sometimes performed as an alternative diagnostic tool but there are no prospective studies that have evaluated the diagnostic accuracy of airway fluoroscopy for tracheomalacia using a-priori definitions. We determined the sensitivity, specificity, and likelihood predictive ratio of airway fluoroscopy compared with FB in children suspected of having an airway abnormality.

METHODS

Airway fluoroscopic examination was undertaken within 2-weeks of a FB in children aged <18-years and reported by a pediatric radiologist blinded to FB data. Fluoroscopic and FB methods and diagnostic criteria were standardized and defined a-priori. Tracheomalacia diagnosed by FB were independently scored (mild, moderate, severe) by 2 pulmonologists in a blinded manner.

RESULTS

In 22 children (median age 33 months, range 1-187) evaluated for airway abnormality, tracheomalacia was found in 21 children at bronchoscopy. Of these, fluoroscopy detected tracheomalacia in five children. Airway fluoroscopy was poorly sensitive (23.8%) but highly specific (100%), positive likelihood ratio was 8.6. However, in moderate-severe tracheomalacia, the sensitivity improved to 57.1% but the specificity reduced (93.3%). The agreement between bronchoscopists for tracheomalacia severity was excellent, weighted kappa 0.74 (95% CI 0.77, 0.98).

CONCLUSION

Airway fluoroscopy cannot replace FB which remains the tool for definitively diagnosing airway malacia. However, in absence of other modalities for diagnosis fluoroscopy should be considered in the setting of persistent respiratory symptoms compatible with the clinical picture of tracheomalacia.

Reversible airway obstruction caused by changing the size and length of an endotracheal tube in a premature neonate with suspected tracheomalacia -A case report-

Tracheomalacia is a malformation of the tracheal membranosa. It is maintained during spontaneous breathing but can be altered by bronchoscopy or positive airway pressure. Tracheomalacia is associated with a high mortality and may cause prolonged intubation and ventilation. Here, the case of a 13-day-old infant with jejunoileal stenosis that had surgery is reported. During induction of general anesthesia, endotracheal intubation was attempted several times with different sized endotracheal tubes. Airway obstruction occurred after the endotracheal intubation. After the airway was maintained, the operation was completed. Tracheomalacia was diagnosed after otolaryngology evaluation postoperatively.

FGF10 controls the patterning of the tracheal cartilage rings via Shh

During embryonic development, appropriate dorsoventral patterning of the trachea leads to the formation of periodic cartilage rings from the ventral mesenchyme and continuous smooth muscle from the dorsal mesenchyme. In this work, we have investigated the role of two crucial morphogens, fibroblast growth factor 10 and sonic hedgehog, in the formation of periodically alternating cartilaginous and non-cartilaginous domains in the ventral mesenchyme. Using a combination of gain- and loss-of-function approaches for FGF10 and SHH, we demonstrate that precise spatio-temporal patterns and appropriate levels of expression of these two signaling molecules in the ventral area are crucial between embryonic day 11.5 and 13.5 for the proper patterning of the cartilage rings. We conclude that the expression level of FGF10 in the mesenchyme has to be within a critical range to allow for periodic expression of Shh in the ventral epithelium, and consequently for the correct patterning of the cartilage rings. We propose that disturbed balances of Fgf10 and Shh may explain a subset of human tracheomalacia without tracheo-esophageal fistula or tracheal atresia.

Lung organogenesis

Developmental lung biology is a field that has the potential for significant human impact: lung disease at the extremes of age continues to cause major morbidity and mortality worldwide. Understanding how the lung develops holds the promise that investigators can use this knowledge to aid lung repair and regeneration. In the decade since the "molecular embryology" of the lung was first comprehensively reviewed, new challenges have emerged-and it is on these that we focus the current review. Firstly, there is a critical need to understand the progenitor cell biology of the lung in order to exploit the potential of stem cells for the treatment of lung disease. Secondly, the current familiar descriptions of lung morphogenesis governed by growth and transcription factors need to be elaborated upon with the reinclusion and reconsideration of other factors, such as mechanics, in lung growth. Thirdly, efforts to parse the finer detail of lung bud signaling may need to be combined with broader consideration of overarching mechanisms that may be therapeutically easier to target: in this arena, we advance the proposal that looking at the lung in general (and branching in particular) in terms of clocks may yield unexpected benefits.

Recombinant human DNase in children with airway malacia and lower respiratory tract infection

BACKGROUND

Children with airway malacia often have protracted courses of airway infections, because dynamic airway collapse during coughing results in impaired mucociliary clearance. The aim of this study was to determine the effect of the mucolytic drug recombinant human deoxyribonuclease (rhDNase) on the recovery of respiratory symptoms in children with airway malacia and lower respiratory tract infection (LRTI).

METHODS

In a randomized double-blind controlled clinical trial, 40 children with airway malacia and LRTI were randomly assigned to receive either 2.5 mg nebulized rhDNase or placebo twice daily for 2 weeks. The primary endpoint was the change in the cough diary score (CDS) (scale 0-5) from baseline to the second week of treatment. Secondary endpoints were VAS symptom scores for cough, dyspnea, and difficulty in expectorating sputum, need for an antibiotic course, and lung function data (FVC, FEV(1), FEF(75), R(int(e))).

RESULTS

There was no significant difference in the mean change in CDSs from baseline between the rhDNase group and the placebo group (mean difference for daytime 0.19 (95% CI -0.53 to 0.90); for nighttime 0.38 (95% CI -0.30 to 1.05). Proportions of patients requiring antibiotics, and the mean changes in symptom scores and lung function from baseline did not significantly differ between both groups.

CONCLUSION

Treatment with 2 weeks of nebulized rhDNase does not enhance recovery or reduce the need for antibiotics in children with airway malacia and LRTI. (Controlled-trials.com number, ISRCTN85366144).

Bronchomalacia occurring in monozygotic twins--further information about its inheritance

We report left main-stem bronchomalacia occurring in monozygotic twins that became symptomatic during infancy. This phenomenon has not previously been reported to occur in twins. Little is known about the aetiology of primary bronchomalacia, but this occurrence suggests that there may be a significant genetic component in some cases.

CONCLUSION

Left main-stem bronchomalacia occurring in monozygotic twins suggests that there may be a significant genetic component in some cases and provides further information about the inheritance of this condition.

Surgical treatment of primary tracheal dyskinesia in a 14-month-old child--case report

The primary form of tracheal dyskinesia in early childhood is a rare congenital malformation of unknown origin. The degree of the posterior membranous tracheal wall involvement determines the intensity of obstruction and the severity of the clinical picture. The aim of this paper is to present a case of a 14-month-old child with severe tracheal dyskinesia that required surgical treatment. Fascia lata graft fixated with fibrin glue was used in strengthening the posterior tracheal wall. Three years following the surgery, the child is without breathing difficulties. In severe cases of primary dyskinesia, surgical treatment using fascia lata graft, fixated with fibrin glue is recommended in strengthening the posterior tracheal wall.

Forced inspiratory flow volume curve in healthy young children

INTRODUCTION

Spirometry testing should include both expiratory and inspiratory measurements. Inspiratory forced maneuvers can demonstrate extrathoracic airway abnormalities, of which various symptoms may suggest asthma. However, the inspiratory portion of the forced flow/volume maneuver in young healthy children has not yet been described.

OBJECTIVES

To document and analyze the forced inspiratory flow volume curve indices in healthy young children.

SETTINGS AND PARTICIPANTS

Healthy preschool children (age 2.5-6.5 years) from community kindergartens around Israel.

METHODS

The teaching method included multi-target, interactive spirometry games and accessory games for inspiration (e.g., inspiratory whistle).

RESULTS

One hundred and fourteen out of a total of 157 children performed duplicate full adequate inspiratory maneuvers. Repeatability between two maneuvers was 5.6%, 4.0%, 5.1%, 7.3% for inspiratory capacity (IC), forced inspiratory vital capacity (FIVC), peak inspiratory flow (PIF), and mid inspiratory flow (FIF50). Inspiratory flow indices were significantly lower than the expiratory flow indices. The time to reach PIF was significantly longer (mean +/- SD; 229 +/- 21 msec) than the time to reach peak expiratory flow (92 +/- 8 msec; P < 0.0001). The shape of the inspiratory curve was parabolic and did not vary with age. The formed predicted equations were in agreement with the extrapolated values for older healthy children.

CONCLUSIONS

The majority of healthy young children can perform reliable maximum inspiratory flow volume curves. Our results provide a framework of reference equations for maximum inspiratory flow volume curve in the young children. The clinical applications of these equations have to be explored.

Diagnosis of airway malacia by virtual bronchoscopy

The study was aimed to identify the role of virtual bronchoscopy in detection of airway malacia in children. In a pre-experimental study over 3 years (from Nov. 2003 to Oct. 2006), 35 consecutive patients were presented to Tabriz Children's Hospital with clinical manifestations of airway malacia, examined by the technique of virtual bronchoscopy. Thirty five patients including 23 males and 12 females with the mean age of 3.7 +/- 1.6 months were studied. The presence of airway malacia and its location and severity were determined by virtual bronchoscopy in all studied cases; that revealed: laryngomalacia, bronchomalacia, tracheomalacia, laryngotracheomalacia and laryngobronchomalacia in 42.8, 25.7, 20, 8.6 and 2.9% of patients, respectively. Virtual bronchoscopy is a non-invasive, accurate and rapid imaging technique with an excellent validity for diagnosis of airway malacia and stenosis, therefore it can replace conventional bronchoscopy.

Clinical manifestations of airway malacia in young children

A case of recurrent respiratory distress, wheezing, and "noisy" breathing in a 6-month-old infant with a normal birth history and chest radiographic evaluation is presented. The distinction between primary and secondary tracheomalacia is outlined. This report emphasizes the importance of clinical history in the evaluation of primary tracheomalacia.