Tracheomalacia

Further experience with polydioxanone airway stents in children

INTRODUCTION

The aims of this study were to update our experience with biodegradable polydioxanone (PDO) airway stents in children, focusing on effectiveness and safety, and to analyze the factors involved in the different outcomes observed.

MATERIALS AND METHODS

Retrospective study of patients managed with PDO stents from 2012 to 2023. Variables collected: demographics, comorbidities, indication, clinical baseline, stent size, location, complications, clinical outcome, and time of follow-up. Statistical analyses were performed to detect the eventual contribution of variables in the different outcomes observed.

RESULTS

Fifty-four PDO stents were placed in 26 patients (median age, 4 months). All showed severe symptoms of central airway obstruction due to tracheomalacia in nine patients, bronchomalacia five, tracheobronchomalacia 10, and tracheal stenosis two. Stent placement was uneventful in every case: 29 stents in the trachea and 25 in the main bronchi. 53.8% of patients needed successive stenting, and all exhibited comorbidities. Complete clinical resolution was observed in eight cases (30.7%), partial improvement in 13 (50%), unchanged in 4 (15.3%), and worsened in one. Age had a significant positive impact on outcome (6 vs. 3 months; p = 0.024). Additionally, smaller stents were associated with a better outcome (20 vs. 26 mm; p = 0.044). Granulation tissue was the most frequent complication (34.6%). Five patients (19.2%) died due to severe comorbidities, follow-up was complete in survivors (median, 58 months).

CONCLUSIONS

PDO stents are safe and effective when dealing with severe tracheobronchial obstruction. Stent-related granulation tissue continues to be a relevant matter of concern. This issue, together with increased degradation times, deserves further research.

Endoscopic Chemocauterization with Trichloroacetic Acid for Congenital or Recurrent Tracheoesophageal Fistula in Children with Esophageal Atresia: Experience from a Tertiary Center

BACKGROUND

Recurrent tracheoesophageal fistula (rTEF) is a well-known complication after surgery of EA, occurring in roughly 3-10% of the patients. Recent studies have highlighted safety and efficacy of endoscopic management of recurrent TEF. The aim of this study was to evaluate the efficacy of chemocauterization with trichloroacetic acid (TCA) in rTEF and congenital tracheoesophageal fistula (cTEF).

METHODS

Retrospective chart review of consecutive patients with recurrent or congenital TEF who underwent endoscopic chemo-cauterization between 2018 and 2022 at a tertiary center. Children diagnosed with TEF who underwent primary or secondary endoscopic treatment were included. Median follow up time was 19 months for rTEF and 33 months for cTEF.

RESULTS

During the study period, 18 patients were treated endoscopically by chemocatuerization with TCA at our institution. Treatment of recurrent TEF was successful in 13 of 14 patients (93%) Treatment of congenital TEF was successful in 2 of 4 patients (50%). In 14 patients, closure was seen after 1-2 treatments. There were no serious adverse reactions or complications to the endoscopic treatment of TEF.

CONCLUSION

Endoscopic chemocauterization is a minimal invasive technique with low morbidity and high success rate and may be considered as primary treatment for recurrent TEF.

LEVEL OF EVIDENCE

III.

Study on the rationality of small diameter metallic airway stent in treatment of tracheal stenosis in injured rabbits

BACKGROUND

To observe the occurrence of related complications after self-expandable metallic (SEM) airway stents implantation with different diameters at different time points, and to provide theoretical basis for the optimal chioce of existing airway stents in clinical practice.

METHODS

Healthy New Zealand white rabbits were used to establish benign tracheal stenosis models after chest CT examination. Forty-fivemodel rabbits with more than 50% of airway stenosis were divided into two groups. Small-diameter SEM stents (The ratio of stent diameter to airway diameter is nearly 1.0) were implanted in Group A in 21 rabbits, and large-diameter tracheal stents (The ratio of stent diameter to airway diameter is more than 1.2) were implanted in Group B in 24 rabbits. Stent-related complications were observed after stent implantation in 2nd,4th,8th, and 12th week by bronchoscopygross anatomy, pathological and the expressions of IL-1RA, IL-8 and MMP9 in involved tracheal.

RESULTS

The incidence rate of tracheomalacia of stent was significantly higher in group B (24/24 100%) than that in group A (1 /21,4.8%) (P < 0.05). The incidence rate of scar contracture at both ends of stent was significantly higher than in group B (11 / 24,45.8%) that in group A (2 /21, 9.5%) (P < 0.05). The pathological results of both A and B showed that the columnar epithelium of bronchial mucosa began to damage and detach, inflammatory cells infiltrated after 2nd and 4th week of stenting, The epithelium was repaired, the lamina propria glands almost disappeared, collagen fiber proliferation was obvious, and scars were formed after 8th and 12th week of stenting. ELISA results revealed that the expressions of IL-1RA, IL-8, and MMP9 were increased in the stent group than in model rabbit with benign tracheal stenosis. IL-1RA and MMP9 increased at different periods in group B, but the expression of IL-1RA and MMP9 showed a tread of increasing in the early stage and then decreasing in group A.

CONCLUSION

Metal stents can cause different degrees of stent-related complications in rabbits with benign tracheal stenosis. The incidence of stent-induced tracheomalacia and scar contracture were higher in Group B than that in Group A. IL-1RA, IL-8 and MMP9 may be involved in the development of complications after stentimplantation and peak value of group B movered backward. ing.

Single-center review on safety of biodegradable airway stenting in pediatric population

BACKGROUND

Tracheobronchomalacia (TBM) and airway stenosis are recognized etiologies of airway obstruction among children. Their management is often challenging, requiring multiple interventions and prolonged respiratory support with associated long-term morbidity. Metallic or silicone stents have been used with mixed success and high complication rates. More recently biodegradable Ella stents (BES) provided an attractive interventional option.

OBJECTIVES

We report our experience in the treatment of TBM and vascular airway compression using BES. We deliberately downsized them to minimize intraluminal granulation tissue formation.

MATERIALS AND METHODS

Retrospective study over an 8-year period between November 2012 and December 2020 of pediatric patients with severe airway obstruction requiring airway stenting for extubation failure, malacic death spells, recurrent chest infections, or lung collapse.

RESULTS

Thirty-three patients (5 tracheal and 28 bronchial diseases) required 55 BES during the study period. The smallest patient weighed 1.8 kg. Median age of patient at first stent implantation was 13.1 months (IQR 4.9-58.3). The majority of the bronchial stents were in the left main bronchus (93%), of which 57% for vascular compression. Repeat stents were used in 19 patients (57.7%), with a range of two to four times. We did not experience erosion, infection, or obstructive granuloma needing removal by forceps or lasering. Three stent grid occluded with secretions needing bronchoscopic lavage. Stent migration occurred in three patients.

CONCLUSIONS

BES holds promise as a treatment option with low rate of adverse effects for a specific subset of pediatric patients with airway malacia or vascular compression. Further studies are warranted.

Outcomes of pediatric tracheostomy after surgery for congenital heart disease: A 20-year experience

Objective

Children with congenital heart defects (CHD) requiring cardiovascular surgery (CVS) rarely require tracheostomy placement; however the mortality rate remains high. The study aimed to analyze the incidence of tracheostomy in children with CHD, and to determine factors contributing to postoperative outcomes, decannulation rates, and mortality.

Methods

Retrospective case series of children ≤18 years old with CHD status post-CVS who underwent tracheostomy placement between January 1, 2001 and December 31, 2020. Variables analyzed included demographic information, presence of comorbidities including prematurity, respiratory diseases, presence of genetic syndromes, decannulation status, type of repair (univentricular vs. biventricular), and need for cardiopulmonary bypass. Adverse events analyzed included all-cause mortality, development of mediastinitis, fatal decannulation, and persistence of tracheocutaneous fistula.

Results

Fifty-one patients were analyzed. The incidence of tracheostomy was 0.8%. Median age at tracheostomy was 5.3 months. The 5-year survival estimate was 56.3% (95% confidence interval 43.6%, 72.6%). Age ≤6 months at the time of tracheostomy placement (p = .03), and the presence of tracheomalacia (p = .04) were factors significantly associated with 5-year survival. Two patients (3.9%) experienced fatal decannulation, and one patient (2.0%) developed postoperative mediastinitis. The 10-year decannulation rate estimate was 47.8% (30.5%, 63.2%). Seven patients (13.7%) had a persistent tracheocutaneous fistula.

Conclusions

This study corroborates high mortality rates in this population. Factors associated with improved survival were younger age at the time of tracheostomy and presence of tracheomalacia. Decannulation rates were low, but estimates improved over 10 years. Further studies are needed to determine optimal indications and timing for tracheostomy placement in this patient population.

Level of Evidence

4.

Pediatric airway compression in aortic arch malformations: a multidisciplinary approach

Background

Aortic arch malformations (AAMs) should be suspected in the presence of persistent respiratory symptoms despite medical treatment or feeding problems at the pediatric age.

Aim

We report a descriptive cohort of patients with AAMs and the local management protocol applied.

Methods

A total of 59 patients with AAM were retrospectively reviewed. Three groups were identified: double aortic arch (DAA), group 1; complete vascular ring (non-DAA), group 2; and anomalous origin of the innominate artery (IA), group 3.

Results

Prenatal diagnosis was available for 62.7% of the patients. In all, 49.2% of children were symptomatic. There was a significantly different prevalence of respiratory symptoms within the three groups: 73.7% in group 1, 24.2% in group 2, and 100% in group 3 (p-value: <0.001). Surgery was considered in the presence of symptoms in patients with DAA and in those with reduction of the tracheal section area greater than 50%. A total of 52.5% of the patients underwent surgical repair (median age 6 months). The median follow-up interval was 21.9 months. Respiratory symptoms improved in most symptomatic patients.

Conclusions

No specific protocols are available for the management of patients with AAMs. Conservative treatment seems to be reasonable for asymptomatic patients or those with airway stenosis less than 50%. A close follow-up is necessary to identify early patients who become symptomatic.

Isolated Tracheabronchomalacia Misdiagnosed for Years as Bronchial Asthma

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

Pulmonary function of children with tracheomalacia and associated clinical factors

OBJECTIVES

Spirometry is easily accessible yet there is limited data in children with tracheomalacia. Availability of such data may inform clinical practice. We aimed to describe spirometry indices of children with tracheomalacia, including Empey index and flow-volume curve pattern, and determine whether these indices relate with bronchoscopic features.

METHODS

From the database of children with tracheomalacia diagnosed during 2016-2019, we reviewed their flexible bronchoscopy and spirometry data in a blinded manner. We specially evaluated several spirometry indices and tracheomalacia features (cross-sectional lumen reduction, malacic length, and presence of bronchomalacia) and determined their association using multivariable regression.

RESULTS

Of 53 children with tracheomalacia, the mean (SD) peak expiratory flow (PEF) was below the normal range [68.9 percent of predicted value (23.08)]. However, all other spirometry parameters were within normal range [Z-score forced expired volume in 1 s (FEV₁ ) = -1.18 (1.39), forced vital capacity (FVC) = -0.61 (1.46), forced expiratory flow between 25% and 75% of vital capacity​​​​​​ (FEF_25%-75% ) = -1.43 (1.10), FEV₁ /FVC = -1.04 (1.08)], Empey Index = 8.21 (1.59). The most common flow-volume curve pattern was the "knee" pattern (n = 39, 73.6%). Multivariable linear regression identified the presence of bronchomalacia was significantly associated with lower flows: FEV₁ [coefficient (95% CI) -0.78 (-1.54, -0.02)], FEF_25%-75% [-0.61 (-1.22, 0)], and PEF [-12.69 (-21.13, -4.25)], all p ≤ 0.05. Other bronchoscopic-defined tracheomalacia features examined (cross-sectional lumen reduction, malacic length) were not significantly associated with spirometry indices.

CONCLUSION

The "knee" pattern in spirometry flow-volume curve is common in children with tracheomalacia but other indices, including Empey index, cannot be used to characterize tracheomalacia. Spirometry indices were not significantly associated with bronchoscopic tracheomalacia features but children with tracheobronchomalacia have significantly lower flow than those with tracheomalacia alone.

Histological and structural effects of biodegradable polydioxanone stents in the rabbit trachea

OBJECTIVES

The aim of this study was to evaluate the potential biologic effects caused by successive placement of biodegradable polydioxanone (PDO) stents in the rabbit trachea. PDO stents could eventually induce a fibroproliferative reaction in the submucosa that could be beneficial in the treatment of malacia due to an increase in its consistency without impairing the tracheal lumen.

METHODS

Sixteen adult NZ rabbits were distributed into 3 groups with different survival times according to the number of stents placed: One stent (14 weeks), 2 stents (28 w.), and 3 stents (42 w.). Stent insertion was performed endoscopically in the cervical trachea of the animal. Histopathological studies included Masson's trichrome staining for submucosal fibrosis and Safranin O to assess structural integrity of cartilage. Potential inflammatory changes were analysed by means of immunohistochemistry determining the number of CD45 positive cells.

RESULTS

Stent placement was successful in every case. Histological studies did not show a statistically significant increase in tracheal wall collagen area and cartilage structure was not modified in those rabbits with one or more PDO stents inserted compared to non-stented tracheal sections. Furthermore, no statistically significant changes in the number of CD45+ cells were observed in stented tracheal segments compared to normal tracheal tissues.

CONCLUSIONS

According to our data, successive PDO stenting caused mild inflammatory changes in the tracheal wall, no increase in the collagen matrix, and the cartilaginous support was not modified during a long follow-up period (up to 42 weeks). These findings suggest that they may be safe and show good biocompatibility in the long-term.

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.

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.

Airway Malacia: Clinical Features and Surgical Related Issues, a Ten-Year Experience from a Tertiary Pediatric Hospital

Background: Few studies have been carried out with the aim of describing the clinical course and follow-up of patients with tracheomalacia. We aim to describe the symptoms at diagnosis and the post-treatment clinical course of patients affected by airway malacia. Methods: We retrospectively analyzed characteristics of pediatric patients with a diagnosis of airway malacia. Patients were classified into three groups: bronchomalacia (BM), tracheomalacia (TM) and tracheo-bronchomalacia (TBM). Demographic and clinical data, diagnostic work-up and surgical treatment were recorded. Results: 13/42 patients were affected by congenital syndromes (30.9%). Esophageal atresia with or without tracheal-esophageal fistula (EA/TEF) was detected in 7/42 patients (16.7%). Cardiovascular anomalies were found in 9/42 (21.4%) and idiopathic forms in 13/42 (30.9%). BM occurred in 7/42 (16.6%), TM in 23/42 (54.7%) and TBM in 12/42 (28.6%). At the diagnosis stage, a chronic cough was reported in 50% of cases with a higher prevalence in EA/TEF (p = 0.005). Surgery was performed in 16/42 (40%) of children. A chronic cough and acute respiratory failure were correlated to the need for surgery. During follow-up, there was no difference in persistence of symptoms between conservative vs surgical treatment (p = 0.47). Conclusion: the management of tracheomalacia remains a challenge for pediatricians. Clinical manifestations, such as a barking cough and acute respiratory failure may suggest the need for surgery. Follow-up is crucial, especially in those patients affected by comorbidities, so as to be able to manage effectively the possible persistence of symptoms, including those that may continue after surgical treatment.

Ear Deformations in Preterm Newborns: Non-Surgical Treatment

ABSTRACT

Approximately 30% of newborns have some degree of congenital ear anomalies, the minority will resolve spontaneously. Deformations can be treated non-surgically, when diagnosed early, whereas malformations surgically only. The authors use the EarWell system proven to achieve excellent results in treating deformations. Although prematurity might raise the risk of ear-deformations compared to term infants, in our experience, there is a longer time frame until effective treatment is initiated due to the cartilage malleability.Treatment included splinting with retractors and taping or a custom-made silicone ear-mold if necessary. Patients were examined weekly, and treatment continued until appropriate ear shape was achieved (6-14 weeks).The authors treated 8 preterm infants during 2018 to 2020 with the above method. Average age of application was 9.25 weeks; treatment was initiated in all patients before the age of 12 weeks. 5/8 had a right-side, 2/8 a left-side, and one a bilateral deformation. Average treatment duration was 10 ± 2.9 weeks. Assessment of satisfaction was made by parents via phone questionnaires; most were pleased with the overall result, while 62% were extremely satisfied.The authors observed higher compliance and longer-lasting malleability of the cartilage in preterm compared to term-infants. They also had fewer complications than in the term group, maybe due to their older (actual age), and more resistant and durable skin compared to a term-infant of the same age. The authors recommend initiating treatment in preterm infants later than accepted practice as results were excellent, and despite the longer treatment duration, this is a better treatment option than surgery.

Resorbable airway splint, stents, and 3D reconstruction and printing of the airway in tracheobronchomalacia

Tracheobronchomalacia (TBM) is the most common tracheobronchial obstruction. Most cases are mild to moderate; therefore, they do not need surgical treatment. Severe tracheomalacia, however, represents a diagnostic and therapeutic challenge since they are very heterogeneous. In the armamentarium of resources for the treatment of dynamic airway collapse, splints and stents are two underused strategies and yet, they may represent the best alternative in selected cases. Lately, computed tomography 3D reconstruction of the airway has been used for the design of virtual models that can be 3D-printed for the creation of novel devices to address training, simulation, and biotechnological implants for refractory and severe airway malformations. This manuscript examines the role of resorbable stents, splints, and the 3D reconstruction and printing of the pediatric airway in tracheobronchomalacia.

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.

Advanced Therapies for Severe Tracheobronchomalacia: A Review of the Use of 3D-Printed, Patient-Specific, Externally Implanted, Bioresorbable Airway Splints

Tracheobronchomalacia is a condition of dynamic collapse of the trachea and mainstem bronchi. The clinical significance of tracheobronchomalacia depends on its severity. Mild cases may be medically managed with limited symptomology, while severe cases require advanced therapies, lengthy hospital stays, and carry significant morbidity and mortality. Current therapies for severe tracheobronchomalacia include tracheostomy with prolonged mechanical ventilation, aortopexy, tracheobronchopexy, and intraluminal metallic, silicone, or bioresorbable stents. Three-dimensional (3D)-printed, patient-specific, bioresorbable airway splinting is a novel treatment option that is undergoing investigation in a cohort of critically ill children with severe tracheobronchomalacia. At the time of our last review of our data, 29 splints had been implanted in 15 children with intrathoracic tracheobronchomalacia. The median follow-up was 8.5 months. There were 12 long-term survivors, and all but one lived at home. This article discusses the details of our institution's development and use of 3D-printed, patient-specific, bioresorbable splints for treatment of severe tracheobronchomalacia in the pediatric population.

The role of bioresorbable intraluminal airway stents in pediatric tracheobronchial obstruction: A systematic review

INTRODUCTION

Tracheal stenosis and tracheobronchomalacia are complicated, patient-specific diseases that can be treated with intraluminal stenting. Most commonly, silicone and metal stents are utilized, however, they pose significant early and late morbidity and are further complicated by growth of the airway in the pediatric population. Given recent improvements in materials science, there is a growing body of evidence suggesting a strong role for bioresorbable intraluminal stents in treating pediatric tracheobronchial obstruction.

METHODS

A PubMed.gov literature search was performed on December 3, 2019 and May 15, 2020, and a 2-researcher systematic review was performed following the PRISMA criteria. The following search query was utilized: (((((((bioresorbable) OR bioabsorbable) OR resorbable) OR absorbable) OR biodegradable AND airway) OR trachea) AND stent. A pooled statistical analysis was performed on all reported pediatric patients using SPSS software.

RESULTS

1369 publications were screened and 26 articles with original data were identified. Materials used included polydioxanone (PDO), poly-l-lactic acid (PLLA), polyglycolic acid/poly-l-lactide co-polymer with Proglactin 910 (Vicryl®-PDS®), polycaprolactone (PCL), magnesium alloys, and co-polymers in varying proportions. Twelve articles presented data on human subjects, 8 of which were case series and case reports on pediatric populations using polydioxanone (PDO) stents. Pooled statistical analysis demonstrated an average age of 19 months (range 0.25-144), 56.5% associated with a cardiovascular anomaly, and overall complication rate of 21.7%, with a stent fragment foreign body being the most common (8.7%), followed by significant granulation tissue (4.3%), stent migration (4.3%), and local stenosis (4.3%). Comparative analysis demonstrated short-term improvement (up to 1 month) has a statistically significant association with tracheobronchomalacia versus tracheal stenosis on chi-squared test (p = 0.001). The remaining analyses did not yield statistical significance.

CONCLUSION

The reported application of bioresorbable materials as intraluminal airway stents is positive. All comparative animal studies report biocompatibility and fewer morbidities compared to metal and silicone stents, however, in human studies there are concerns over the short interval of degradation and the potential for obstructive foreign bodies in poorly seated stents. Overall, there are clear, reproducible advantages to bioresorbable intraluminal stents in pediatric airway obstruction, as well as common pitfalls, that warrant further research.

Increased Work of Breathing due to Tracheomalacia in Neonates

Rationale: Dynamic collapse of the tracheal lumen (tracheomalacia) occurs frequently in premature neonates, particularly in those with common comorbidities such as bronchopulmonary dysplasia. The tracheal collapse increases the effort necessary to breathe (work of breathing [WOB]). However, quantifying the increased WOB related to tracheomalacia has previously not been possible. Therefore, it is also not currently possible to separate the impact of tracheomalacia on patient symptoms from parenchymal abnormalities.Objectives: To measure the increase in WOB due to airway motion in individual subjects with and without tracheomalacia and with different types of respiratory support.Methods: Fourteen neonatal intensive care unit subjects not using invasive mechanical ventilation were recruited. In eight, tracheomalacia was diagnosed via clinical bronchoscopy, and six did not have tracheomalacia. Self-gated three-dimensional ultrashort-echo-time magnetic resonance imaging (MRI) was performed on each subject with clinically indicated respiratory support to obtain cine images of tracheal anatomy and motion during the respiratory cycle. The component of WOB due to resistance within the trachea was then calculated via computational fluid dynamics (CFD) simulations of airflow on the basis of the subject's anatomy, motion, and respiratory airflow rates. A second CFD simulation was performed for each subject with the airway held static at its largest (i.e., most open) position to determine the increase in WOB due to airway motion and collapse.Results: The tracheal-resistive component of WOB was increased because of airway motion by an average of 337% ± 295% in subjects with tracheomalacia and 24% ± 14% in subjects without tracheomalacia (P < 0.02). In the tracheomalacia group, subjects who were treated with continuous positive airway pressure (CPAP) using a RAM cannula expended less energy for breathing compared with the subjects who were breathing room air or on a high-flow nasal cannula.Conclusions: Neonatal subjects with tracheomalacia have increased energy expenditure compared with neonates with normal airways, and CPAP may be able to attenuate the increase in respiratory work. Subjects with tracheomalacia expend more energy on the tracheal-resistive component of WOB alone than nontracheomalacia patients expend on the resistive WOB for the entire respiratory system, according to previously reported values. CFD may be able to provide an objective measure of treatment response for children with tracheomalacia.

The role of 3D printing in pediatric airway obstruction: A systematic review

BACKGROUND

Tracheomalacia and tracheal stenosis are complicated, patient-specific diseases that require a multidisciplinary approach to diagnose and treat. Surgical interventions such as aortopexy, slide tracheoplasty, and stents potentially have high rates of morbidity. Given the emergence of three-dimensional (3D) printing as a versatile adjunct in managing complex pathology, there is a growing body of evidence that there is a strong role for 3D printing in both surgical planning and implant creation for pediatric airway obstruction.

METHODS

A structured PubMed.gov literature search was utilized, and a two-researcher systematic review was performed following the PRISMA criteria. The following search query was utilized: (((((3D printing) OR three-dimensional printing) OR 3D printed) OR three-dimensional printed) AND trachea) OR airway.

RESULTS

Over 23,000 publications were screened. Eight literature reviews and thirty-seven original papers met inclusion criteria. Of the thirty-seven original papers, eleven discussed 3D printing for surgical planning and twenty-six discussed 3D printing implants for interventions.

CONCLUSION

The reported application of 3D printing for management of pediatric airway obstruction is emerging with positive and broad applications. 3D printing for surgical planning not only improves pre-operative assessment of surgical approach and stent customization, but also helps facilitate patient/family education. 3D printing for custom implantable interventions is focused on bioresorbable external airway splints and biological grafts, with both animal studies and human case reports showing good results in improving symptoms.

Tracheal cartilage growth promotion by intra-tracheal administration of basic FGF

PURPOSE

This study aimed to investigate whether intra-tracheal administration of basic fibroblast growth factor (b-FGF) promotes the growth of tracheal cartilage.

METHODS

Trachea of 4-week old mice were intubated and 2.5 μg b-FGF administered (Group 4) for periods from 1 to 5 days. Cervical tracheal outer diameter and tracheal ring length were compared in Group 1 (no intervention), Group 2 (tracheal intubation), Group 3 (intra-tracheal administration of distilled water) and Group 4, at 8 weeks of age. Outer diameter and tracheal ring length in Group 4 were also compared with that in Group 1 at 12 and 16 weeks of age.

RESULTS

At 8 weeks of age, tracheal ring length with b-FGF administration for more than 4 days in Group 4 was significantly increased over that following 1-day administration. At 8 weeks of age, mean outer diameter and the mean tracheal ring length in Group 4 were significantly greater than in the other groups. Mean outer diameter and mean tracheal ring length were significantly greater in Group 4 than in Group 1 at 12 and 16 weeks of age.

CONCLUSION

This study has shown that intra-tracheal administration of b-FGF enlarges the tracheal lumen.

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.

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.

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.

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.

Respiratory problems in children with esophageal atresia and tracheoesophageal fistula

Background

Children with congenital esophageal atresia (EA) and tracheoesophageal fistula (TEF) have chronic respiratory symptoms including recurrent pneumonia, wheezing and persistent cough. The aim of this study is to describe the clinical findings of a large group of children with EA and TEF surgically corrected and the instrumental investigation to which they have undergone in order to better understand the patient’s needs and harmonize the care.

Methods

A retrospective data collection was performed on 105 children with EA and TEF followed at Department of Pediatric Medicine of Bambino Gesù Children’s Hospital (Rome, Italy) between 2010 and 2015.

Results

69/105 (66%) children reported lower respiratory symptoms with a mean age onset of 2.2 ± 2.5 years and only 63/69 (91%) performed specialist assessment at Respiratory Unit. Recurrent pneumonia (33%) and wheezing (31%) were the most reported symptoms. The first respiratory evaluation was performed after surgically correction of gastroesophageal reflux (GER) at mean age of 3.9 ± 4.2 years. Twenty nine patients have undergone to chest CT with contrast enhancement detecting localized atelectasis (41%), residual tracheal diverticulum (34%), bronchiectasis (31%), tracheal vascular compression (21%), tracheomalacia (17%) and esophageal diverticulum (14%). Fifty three patients have undergone to airways endoscopy detecting tracheomalacia (66%), residual tracheal diverticulum (26%), recurrent tracheoesophageal fistula (19%) and vocal cord paralysis (11%).

Conclusions

Our study confirms that respiratory symptoms often complicate EA and TEF; their persistence despite medical and surgical treatment of GER means that other etiological hypothesis must be examined and that a complete respiratory diagnostic work up must be considered.

Perioperative nursing of tracheal silicon stent implantation in infants: report on four cases

AIMS

To report experience of perioperative nursing of tracheal silicon stent implantation in infants.

METHODS

Retrospective analysis on the cases of tracheal silicon stent implantation in infants in our hospital.

RESULTS AND CONCLUSIONS

Since middle of 2014, totally four tracheal silicon stent implantation were performed in our center. Of them, one case was recurrent tracheoesophageal fistula and the other three cases were traheomalacia. Parent's psychological support, infants' nutrition support and airway care were key responsibility for a nurse before implantation. During the procedure of stent implantation, it was responsible for a nurse to closely monitor the infants and to support operator. After the implantation, airway care and prevention of intra-airway bacterial colonization were important to avoid complications.

Tracheobronchomalacia as a Rare Cause of Chronic Dyspnea in Adults

OBJECTIVE

To emphasize the importance of a careful clinical evaluation to prevent unnecessary interventions and treatments.

CLINICAL PRESENTATION AND INTERVENTION

A 76-year-old female patient had been diagnosed with asthma during previous admissions to different hospitals. She had also undergone fiberoptic bronchoscopy (FOB) on 2 occasions for evaluation of right middle lobe atelectasis observed on computed tomography. A repeated FOB revealed tracheobronchomalacia and nodular bronchial amyloidosis. A silicone Y stent was inserted, but the dyspnea increased. Excessive granulation tissue developed, and the patient died despite ventilatory support.

CONCLUSION

The stenting technique used did not prevent the development of respiratory failure and death in this patient. Hence, a surgical procedure could be considered as an alternative to stenting in such cases.

The Management of Cyanotic Spells in Children with Oesophageal Atresia

Cyanotic spells, also known as blue spells, dying spells, or apparent life-threatening events, refer to a bluish tone visible in the mucosal membranes and skin caused by an oxygen decrease in the peripheral circulation. Although this decrease may be transient and benign, it may also be indicative of a severe underlying problem that requires immediate intervention. Children with oesophageal atresia (OA) are at risk for a number of coexisting conditions that may trigger cyanotic spells. This current article will focus on the management of cyanotic spells both in children with innominate artery compression and those with tracheomalacia.

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

Background

Wheezing is a common symptom in early childhood. However, refractory wheezing is difficult to treat, and it may thus account for extensive use of medical resources. It is therefore important to improve our understanding of the pathophysiology of refractory childhood wheezing.

Methods

In this descriptive study, we studied 156 children with refractory wheezing using fiberoptic bronchoscopy and bronchoalveolar lavage (BAL), and compared the results with a control group of 46 children with various pulmonary diseases but no wheezing. Etiology and cell classification were analyzed for each BAL sample.

Results

Overall, 21.8 % of children with refractory wheezing had airway malformations including tracheomalacia, airway stenosis, and tracheal bronchus. The incidence of airway malformations increased to 31 % in infants under 12 months of age. A significant increase in neutrophil ratio and decrease in macrophage ratio were observed in BAL from children with refractory wheezing compared with controls. Pathogen infection led to a higher ratio of neutrophils in the wheezing group compared with controls. However, there were no significant differences in neutrophil ratios among children with various pathogen infections. Furthermore, children with refractory wheezing had a high rate of Mycoplasma pneumoniae infection.

Conclusions

Airway malformations might play an important role in children under 3 years of age with refractory wheezing, especially in infants under 12 months of age. Neutrophil-mediated airway inflammation was characteristic of refractory wheezing in children under 3 years of age. In addition, infections such as M. pneumoniae may aggravate airway inflammation and affect refractory wheezing.

Pediatric tracheomalacia

Tracheomalacia (TM) is defined as an increased collapsibility of the trachea due to structural anomalies of the tracheal cartilage and/or posterior membrane. Tracheomalacia has a wide range of etiologies but is most commonly present in children born with esophageal atresia and tracheal esophageal fistula. Clinical symptoms can range from minor expiratory stridor with typical barking cough to severe respiratory distress episodes to acute life-threatening events (ALTE). Although the majority of children have mild-to-moderate symptoms and will not need surgical intervention, some will need life-changing surgical treatment. This article examines the published pediatric literature on TM, discusses the details of clinical presentation, evaluation, diagnosis, and a variety of treatments.

Evaluation of aortopexy in the management of severe tracheomalacia after esophageal atresia repair

Severe tracheomalacia (TM) is a difficult problem in esophageal atresia (EA) patients. We reviewed our experience with aortopexy and other interventions for severe TM in this population. With review ethics board approval, a retrospective review of TM in postoperative EA patients was conducted (1989-2010). Demographics, perinatal, and surgical information regarding EA repair was collected. TM infants were analyzed for symptomatology, clinical severity, investigations, interventions, and outcomes. Data are presented as proportions or median(range). One hundred and thirty-two EA patients were reviewed. Most had type C atresia (87.3%), and 18 patients (13.6%) died. Twenty-five patients (18.9%) had TM of whom five (20%) died. Median symptom onset was 18 days (0-729) after EA repair, with stridor (64%) or retractions/distress (44%) being most frequent. Four and two patients had airway obstruction or cardiorespiratory arrest, respectively. Median time from symptom onset to investigations was 11 days; these were most commonly rigid bronchoscopy (56%) and fluoroscopy (36%). Ten patients (40%) had severe TM on bronchoscopy. Six underwent aortopexy, one fundoplication, and three were treated medically. Length of hospital stay (LOS) post-aortopexy was 13 days (5-60), and ventilation time was 2 days (0-9). LOS was 60.5 (1-69) days postdiagnosis in non-aortopexy patients. Readmission rates for respiratory issues were significantly less in the aortopexy (median 0 vs. 5; P = 0.048) group over 2-year follow up after discharge. Complications of aortopexy included transfusion (1) and temporary diaphragmatic paresis (1), and one mortality secondary to severe congenital cardiac anomalies. Our experience suggests that aortopexy is safe and effective for the treatment of severe TM. It is associated with reduced LOS compared with other treatment strategies and few complications or long-term sequelae.

Tracheobronchial issues in congenital heart disease

In children with congenital heart disease, tracheobronchial compromise is uncommon but potentially life-threatening. Airway lesions in these patients may be congenital or acquired, and may be stenotic, compressive, or malacic in nature. We present an overview of the etiologies of tracheobronchial lesions typically seen in children with congenital heart disease and review management options for these lesions.

Isolated severe bilateral bronchomalacia

Airway malacia is uncommon condition having symptoms similar to common respiratory illnesses. Any child having persistent wheeze during infancy should be evaluated for airway malacia. The authors report a case of isolated severe bilateral bronchomalacia managed with tracheostomy and continuous positive pressure ventilation.

Promotion of tracheal cartilage growth by intra-tracheal injection of basic fibroblast growth factor (b-FGF)

PURPOSE

Basic fibroblast growth factor (b-FGF) is a very effective growth factor that induces the proliferation of chondrocytes. This study aimed to investigate whether intra-tracheally-injected b-FGF solution promotes the growth of tracheal cartilage.

METHODS

Group 1: 500 μl of distilled water was injected at the posterior wall of the cervical trachea of New Zealand white rabbits by using a tracheoscope (n=5). Group 2: 100 μg/500 μl of b-FGF solution was injected at the posterior wall of the cervical trachea (n=5). Group 3: Biodegradable gelatin hydrogel microspheres incorporating 100 μg/500 μl of b-FGF solution were injected at the posterior wall of the cervical trachea (n=5). All animals were sacrificed 4 weeks later, and the outer diameter and luminal area of the cervical trachea at the site of b-FGF injection were measured.

RESULTS

The cervical tracheas in the two b-FGF injection groups were spindle-shaped and had a maximum diameter at the injection site. The median outer diameter of the cervical trachea in Groups 1, 2, and 3 was 7.3, 8.0, and 8.0mm, respectively, showing a significant difference among Groups 1, 2, and 3 (P=0.04). The median luminal area in Groups 1, 2, and 3 was 27.4, 29.4, and 32.1mm(2), respectively. The ad hoc test showed a marginally significant difference only between groups 1 and 3 (p=0.056).

CONCLUSION

Intra-tracheal injection of slowly released b-FGF enlarged the tracheal lumen.

Combined effects of the C161T and Pro12Ala PPARγ2 gene variants with insulin resistance on metabolic syndrome: a case-control study of a central Tunisian population

We investigated the synergism between variants at the PPARγ locus (C161T and Pro12Ala polymorphisms) with insulin resistance on metabolic syndrome (MS). Five hundred twenty-two subjects were investigated for biochemical and anthropometric measurements. The diagnosis of MS was based on the IDF definition (2009). The HOMA 2 was used to determine HOMA-β, HOMA-S, and HOMA-IR from FPG and FPI concentrations. PCR-RFLP was performed for DNA genotyping. We showed that carriers of the Pro/Pro had a significantly higher FPG, FPI, and HOMA-IR. In addition, Pro/Pro subjects also display reduced HOMA-β and HOMA-S together compared to X/Ala (Pro/Ala and Ala/Ala) subjects. Furthermore, subjects with C/C have a significantly lower FPG, FPI, and HOMA-IR and higher HOMA-S compared to X/T (C/T and T/T) subjects. The C/C genotype carriers with an Ala allele group had significantly reduced FPG, FPI, HOMA-IR, and TG and elevated HOMA-S and HOMA-β than the different genotype combinations. We suggest that the haplotype composed of the C/C genotype carriers with an Ala allele of PPARγ2 group enhances susceptibility to the MS in a central Tunisian population.

Improvement of tracheal compression after pectus excavatum repair

A 4-year-old girl with pectus excavatum (PE), multiple prior respiratory infections, tracheomalacia and tracheal compression due to the innominate artery was referred for surgical evaluation. Aortopexy was deemed unlikely to improve airway diameter due to her chest concavity. Thoracoscopy-assisted PE repair was performed, resulting in marked improvement in the anteroposterior diameter of the trachea and resolution of her respiratory symptoms. Durability of the PE correction at 2 and 7 years following bar removal was demonstrated radiographically.

Outcomes of aortopexy for patients with congenital heart disease

Aortopexy is a surgical procedure in which the aortic arch is fixed at other structures, thus widening the interaortic space. This study aimed to evaluate the outcome of aortopexy by means of chest computed tomography for patients with congenital heart disease. The study retrospectively reviewed the medical records of 16 patients with congenital heart disease who had undergone aortopexy by compressed airway. The severity of compressed bronchus before aortopexy, immediately after aortopexy (≤ 1 month), and after the patient had grown up were compared. To estimate the efficacy of the aortopexy, the interaortic distance index was calculated. Of the 16 patients, aortopexy was performed at the ascending aorta in 7, at the descending aorta in 7, and at the transverse arch in 2. The diameter ratio between the narrowest bronchus and the trachea was improved after aortopexy, as was the diameter ratio before aortopexy versus immediately after aortopexy (n = 9; p = 0.018) and the diameter ratio before aortopexy versus after the patient had grown up (n = 11; p = 0.006). Also, the interaortic distance index was increased after aortopexy, as was the diameter before aortopexy versus immediately after aortopexy (n = 9; p = 0.039) and the diameter before aortopexy versus after the patient had grown up (n = 11; p = 0.014). The study had one case of mortality due to sepsis. As shown by the results, aortopexy in patients with a compressed airway between arches is a useful surgical option. Such a compressed airway between arches should be considered for patients with an unusual clinical course before and after open heart surgery.

miRNAs control tracheal chondrocyte differentiation

The specific program that enables the stereotypic differentiation of specialized cartilages, including the trachea, is intrinsically distinct from the program that gives rise to growth plate hypertrophic chondrocytes. For example, Snail1 is an effector of FGF signaling in growth plate pre-hypertrophic chondrocytes, but it derails the normal program of permanent chondrocytes, repressing the transcription of Aggrecan and Collagen type 2a1 (Col2a1). Here we show that miRNA activity is essential for normal trachea development and that miR-125b and miR-30a/c keep Snail1 at low levels, thus enabling full functional differentiation of Col2a1 tracheal chondrocytes. Specific inhibition of miR-125b and miR-30a/c in chondrocytes or Dicer1 knockout in the trachea, de-repress Snail1. As a consequence, the transcription of Aggrecan and Col2a1 is hampered and extracellular matrix deposition is decreased. Our data reveals a new miRNA pathway that is safekeeping the specific genetic program of differentiated and matrix-producing tracheal chondrocytes from acquisition of unwanted signals. This pathway may improve understanding of human primary tracheomalacia and improve protocols for cartilage tissue engineering.

Conservative management of canine tracheal collapse with stanozolol: a double blinded, placebo control clinical trial

The objective of this study is to determine the efficacy of stanozolol in the treatment of tracheal collapse (TC) in dogs, which is the analogous disease to tracheomalacia (TM) in humans. Twenty-two dogs with endoscopically confirmed and graded TC were enrolled into five groups. Groups S1 (n=5), S2 (n=5) and S3 (n=4) with grade 1, 2 and 3 TC, respectively, received stanozolol orally for 75 days, while groups P1 (n=4) and P2 (n=4) with grade 1 and 2 TC, respectively, received placebo. The clinical score was evaluated every 15 days, whereas TC grade was reassessed at the end of the experiment. Clinical improvement was detected from the 30th day in S2 and S3 group dogs and from the 45th day in S1 group dogs and continued until the end of the experiment. Also, statistically significant differences were seen between S2 and P2 dogs from the 30th day, and between S1 and P1 dogs from the 60th day, and continued until the end of the study. Amelioration of the TC grade was seen in 13 of 14 (92.9%) dogs, which received stanozolol. Of the 14 dogs, 57.1% were cured and 35.8% demonstrated a less severe TC grade, while only one dog (7.1%) did not improve at all. Stanozolol seems to be an effective drug in the management of canine TC and it may have potential for use in humans with TM.

PPARgamma gene C161T substitution alters lipid profile in Chinese patients with coronary artery disease and type 2 diabetes mellitus

Background

Peroxisome proliferator-activated receptor γ (PPARγ) is a ligand-activated transcription factor, which regulates gene expression of the key proteins involved in lipid metabolism, vascular inflammation, and proliferation. PPARγ may contribute to attenuating atherogenesis and postangioplasty restenosis. PPARγ C161→T substitution is associated with a reduced risk of coronary artery disease (CAD). Whether or not the gene substitution alters the risk of CAD in type 2 diabetes mellitus (T2DM) patients remains unclear.

Methods

A total of 556 unrelated subjects from a Chinese Han population, including 89 healthy subjects, 78 CAD patients, 86 T2DM patients, and 303 CAD combined with T2DM patients, were recruited to enroll in this study. PPARγC161→T gene polymorphism was determined by polymerase chain reaction and restriction fragment length polymorphisms. Plasma levels of lipoproteins, apolipoproteins, glucose, and insulin were measured by ELISA or radioimmunoassay (RIA). The coronary artery lesions were evaluated by coronary angiography.

Results

The frequency of the 161T allele in CAD, T2DM, and CAD combined with T2DM patients was similar to that observed in the healthy control group. However, in CAD combined with T2DM patients, the group with angiographically documented moderate stenoses had a higher frequency of the 161T allele in comparison to the group with severe stenoses (P < 0.05). Moreover, in CAD with T2DM patients, the triglyceride levels and apoB in CC homozygote carriers were significantly higher than those in "T" allele carriers.

Conclusions

PPARγC161→T genotypes weren't significantly associated with the risk of CAD, but were markedly correlated with severity of disease vessels in patients with CAD and T2DM. Furthermore, PPARγC161→T substitution was associated with an altered adipose, but not glucose metabolism. These results indicate that the PPARγ C161→T polymorphism may reduce the risk of severe atherogenesis by modulation of adipose metabolism, especially triglycerides and apoB, in Chinese patients with CAD and T2DM.

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).