An essential function for autocrine hedgehog signaling in epithelial proliferation and differentiation in the trachea.

The tracheal epithelium is a primary target for pulmonary diseases as it provides a conduit for air flow between the environment and the lung lobes. The cellular and molecular mechanisms underlying airway epithelial cell proliferation and differentiation remain poorly understood. Hedgehog (HH) signaling orchestrates communication between epithelial and mesenchymal cells in the lung, where it modulates stromal cell proliferation, differentiation and signaling back to the epithelium. Here, we reveal a previously unreported autocrine function of HH signaling in airway epithelial cells. Epithelial cell depletion of the ligand sonic hedgehog (SHH) or its effector smoothened (SMO) causes defects in both epithelial cell proliferation and differentiation. In cultured primary human airway epithelial cells, HH signaling inhibition also hampers cell proliferation and differentiation. Epithelial HH function is mediated, at least in part, through transcriptional activation, as HH signaling inhibition leads to downregulation of cell type-specific transcription factor genes in both the mouse trachea and human airway epithelial cells. These results provide new insights into the role of HH signaling in epithelial cell proliferation and differentiation during airway development.

Outcomes for Children With Vascular Ring Repair Using a Simple Surgical Approach.

INTRODUCTION: Vascular Rings (VRs) are congenital malformations of the aortic arch that can compress the trachea and esophagus producing symptoms. Approximately, 5%-10% of patients experience persistent symptoms postrepair and 9% require reintervention. There are various approaches to repair-simple ligation and division of the ring or more complex procedures. Our objective was to describe outcomes for VR repair using a "simple" surgical approach. METHODS: We identified patients who underwent VR repair from 2012 to 2022 at our institution. Clinical and surgical data, demographics, intraoperative, and postoperative outcomes were extracted from their electronic medical records. Outcomes were analyzed and regression analysis was used to identify risk factors for residual symptoms after repair. RESULTS: Ninety three patients with VR repair were included. Prevalence of symptoms were reduced following surgery (80% preoperative versus 13% postoperative, P 0.03). Tracheomalacia also decreased from 16% to 7% postrepair. No deaths were reported in our cohort and 2% of our patients required reintervention. Multivariable regression analysis showed that preoperative tracheomalacia was associated with having persistent symptoms after VR repair (odds ratio 6.2, 95% CI 1.02-37.6). CONCLUSIONS: Our institutional experience using a simple surgical approach showed a significant decrease in symptoms, a very low reintervention rate and no mortality. Preoperative tracheomalacia can be a risk factor for persistent symptoms postrepair. We believe a simple surgical approach for children with complete VR repair can be effective in relieving symptoms.

Negative pressure suction test: An intraoperative airway maneuver to assess effectiveness of surgical correction of tracheobronchomalacia.

BACKGROUND: Surgical correction of tracheobronchomalacia (TBM) has evolved greatly over the past decade, with select pediatric institutions establishing dedicated surgery and anesthesia teams to navigate the complexities and challenges of surgical airway repairs. Although anesthetic techniques have evolved internally over many years to improve patient safety and outcomes, many of these methods remain undescribed in literature. TECHNIQUE: In this article, we describe the intraoperative negative pressure suction test. This simulates the negative pressure seen in awake and spontaneously breathing patients, including the higher pressures seen during coughing which induce airway collapse in patients with TBM. Also known as the Munoz maneuver in surgical literature, this test has been performed on over 300 patients since 2015. DISCUSSION: The negative pressure suction test allows for controlled intraoperative assessment of surgical airway repairs, replaces the need for risky intraoperative wake-up tests, increases the chances of a successful surgical repair, and improves anesthetic management for emergence and extubation. We provide a guide on how to perform the test and videos demonstrating its efficacy in intraoperative airway evaluation. CONCLUSIONS: As surgeries to repair TBM become more prevalent in other pediatric institutions, we believe that pediatric patients and anesthesia providers will benefit from the insights and methods described here.

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

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

[Review of surgical treatment of suprastomal collapse in tracheostomised children]. / Übersichtsarbeit zur chirurgischen Behandlung des suprastomalen Kollapses bei tracheotomierten Kindern.

BACKGROUND: Suprastomal collapse (SSC) is considered a major late complication of paediatric tracheostomy and can be responsible for decannulation failure in up to 20% of tracheostomised children. Depending on the severity of SSC, surgery may be required. Various strategies and techniques are available, of which the treating with airway team should be aware. OBJECTIVE: This article intends to summarise the aetiology of SSC, its classification, clinical presentation, and the gold standard diagnostic and therapeutic algorithms according to the current literature. MATERIALS AND METHODS: A panel of experts reviewed the available literature on SSC. Published evidence on the different surgical techniques and their advantages and disadvantages was reviewed in detail, and a treatment algorithm created. RESULTS: The gold standard diagnostic procedure for SSC is flexible transnasal laryngotracheoscopy in spontaneous breathing followed by microlaryngoscopy (MLS) under general anaesthesia. Two main types of SSC can be differentiated, which differ in terms of surgical treatment. Purely anterior SSC is usually treated by tracheoplasty using an anterior costal cartilage graft (ACCG). Simple closure of the tracheostomy or excision of SSC with a potassium-titanyl-phosphate (KTP) laser are also described as less invasive approaches. For anterolateral SSC, segmental tracheal resection with end-to-end anastomosis or tracheoplasty with ACCG represent promising treatment options. Tracheal reinforcement with absorbable microplates is also discussed in the literature. With both types of SSC and depending on severity and the age of the child, a watch-and-wait strategy should always be considered. CONCLUSION: Dynamic airway endoscopy in spontaneous breathing followed by MLS in general anaesthesia should always be performed before decannulation. It is particularly important to visualise all segments of the airway during spontaneous breathing. The decision regarding the best surgical option for each child is based on the type and localisation of SSC, as well as on the patient's medical and surgical history and age.

Unsuspected severe tracheal stenosis and tracheomalacia after correction surgery for congenital scoliosis: A case report.

Tracheal stenosis and tracheomalacia in patients with congenital scoliosis are serious and rare conditions caused by congenital dysplasia, postintubation injury, trauma, and tracheal tumor. Anesthesia of a child with tracheal stenosis is challenging for anesthesiologists. We describe an 8-year-old female patient developed severe tracheal stenosis and tracheomalacia after growing rod implantation for congenital scoliosis. Comprehensive assessment of preoperative pulmonary function and airway morphology, which can be neglected clinically, should be performed in congenital scoliosis patients.

A case report of tracheal tenting to the skin: An option to tracheostomy for post-thyroidectomy tracheomalacia.

Operating on a huge and long-standing goiter is challenging to the surgeon and anesthetist because of the possibility of tracheomalacia and collapse of the tracheal rings after extubation. We report our innovation of tenting the trachea to the skin using sutures (passed through the strap and sternocleidomastoid muscles) to prevent post-thyroidectomy tracheomalacia.

Imaging in neonatal respiratory disease.

The purpose of this review is to describe the current state of the art in clinical imaging for NICU patients, divided into major areas that correspond to likely phenotypes of neonatal respiratory disease: airway abnormalities, parenchymal disease, and pulmonary vascular disease. All common imaging modalities (ultrasound, X-ray, CT, and MRI) are discussed, with an emphasis on modalities that are most relevant to the individual underlying aspects of disease. Some promising aspects of dynamic and functional imaging are included, where there may be future clinical applicability.

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.

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

BACKGROUND: Esophageal atresia (EA) is often associated with tracheomalacia (TM). The severity of TM symptoms varies widely, with serious cases requiring prolonged respiratory support and surgical treatment. Although we performed thoracoscopic posterior tracheopexy (TPT) during primary EA repair to prevent or reduce the symptoms of TM, few studies have investigated the safety and effectiveness of TPT during primary EA repair. Therefore, this study aimed to evaluate the safety and efficacy of TPT in neonates. METHODS: We retrospectively reviewed the records of all patients diagnosed with TM who underwent primary thoracoscopic EA repair between 2013 and 2020 at the Nagoya University Hospital. Patients were divided into two groups: TPT (TPT group) and without TPT (control group). TPT has been performed in all patients with EA complicated by TM since 2020. We compared patient backgrounds, surgical outcomes, postoperative complications, and treatment efficacy. RESULTS: Of the 22 patients reviewed, eight were in the TPT group and 14 were in the control group. There were no statistically significant differences in the surgical outcomes between the groups (operation time: p = 0.31; blood loss: p = 0.83; time to extubation: p = 0.30; time to start enteral feeding: p = 0.19; time to start oral feeding: p = 0.43). Conversion to open thoracotomy was not performed in any case. The median operative time required for posterior tracheopexy was 10 (8-15) min. There were no statistically significant differences in postoperative complications between the groups (chylothorax: p = 0.36; leakage: p = 1.00; stricture: p = 0.53). The respiratory dependence rate 30 days postoperative (2 [25%] vs. 11 [79%], p = 0.03) and the ratio of the lateral and anterior-posterior diameter of the trachea (LAR) were significantly lower in the TPT group (1.83 [1.66-2.78] vs. 3.59 [1.80-7.70], p = 0.01). CONCLUSIONS: TPT during primary EA repair for treatment of TM significantly lowered respiratory dependence rate at 30 days postoperative without increasing the risk of postoperative complications. This study suggested that TPT could improve TM associated with EA.

[Treatment of post-intensive care tracheal stenosis after previous covid-19 pneumonia]. / Lechenie postreanimatsionnykh rubtsovykh stenozov trakhei posle perenesennoi koronavirusnoi pnevmonii Covid-19.

OBJECTIVE: To analyze postoperative outcomes and perioperative management of patients with post-intensive care tracheal stenosis and previous COVID-19 pneumonia. MATERIAL AND METHODS: There were 8 patients with post-intensive care tracheal stenosis and previous COVID-19 pneumonia aged 34-61 years between January 2021 and April 2021. Lung damage CT-3 was observed in 2 (25%) patients, CT-4 - in 5 (62.5%) patients. In one case, COVID-19 pneumonia with lung damage CT-2 joined to acute cerebrovascular accident. Post-tracheostomy stenosis was detected in 7 (87.5%) cases, post-intubation stenosis - in 1 patient. Duration of invasive mechanical ventilation ranged from 5 to 130 days. In 75% of cases, tracheal stenosis was localized in the larynx and cervical trachea. Two patients admitted with tracheostomy. In one case, an extended tracheal stenosis was combined with atresia of infraglottic part of the larynx. One patient had tracheal stenosis combined with tracheoesophageal fistula (TEF). Length of tracheal stenosis was 15-45 mm. Tracheomalacia was observed in 4 (50%) patients. All patients had severe concomitant diseases. RESULTS: To restore airway patency, we used circular tracheal resection with anastomosis, laryngotracheoplasty and endoscopic methods. Tracheal resection combined with TEF required circular tracheal resection with disconnection of fistula. Adequate breathing through the natural airways was restored in all patients. There was no postoperative mortality. Three patients with baseline tracheal stenosis had favorable postoperative outcomes after circular tracheal resection. Four patients are at the final stage of treatment after laryngotracheoplasty and tracheal stenting. CONCLUSION: Patients after invasive mechanical ventilation for COVID-19 pneumonia are at high risk of cicatricial tracheal stenosis and require follow-up. Circular tracheal resection ensures early rehabilitation and favorable functional results. Laryngotracheoplasty is preferred if circular tracheal resection is impossible. This procedure ensures adequate debridement of tracheobronchial tree and respiratory support. Endoscopic measures are an alternative for open surgery, especially for intrathoracic tracheal stenosis and intractable tracheobronchitis.

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.

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

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

Cinematic rendering enhancements to virtual bronchoscopy: assessment of emergent tracheal pathology.

Utilizing complex lighting models, cinematic rendering is a novel technique for demonstrating computed tomography data with exquisite 3D anatomic detail. The tracheal lumen, tracheal wall, and adjacent soft tissue structures are represented with photorealistic detail exceeding that of conventional volume rendering or virtual bronchoscopy techniques. We applied cinematic rendering to a spectrum of emergent tracheal pathologies: traumatic tracheal tears, tracheoesophageal fistulas, tracheal foreign bodies, tracheal stenosis (intrinsic and extrinsic causes), tracheal neoplasms, and tracheomalacia. Cinematic rendering images enable visually accessible evaluation and comprehensive understanding of acute tracheal pathology, which is likely to be of value to both interventional pulmonologists and thoracic surgeons who are determining patient treatment plans.

Development pattern of tracheal cartilage in human embryos.

INTRODUCTION: Congenital tracheal anomalies are associated with high morbidity and mortality. The etiology of congenital tracheal anomalies is not well understood, but often attributed to malformed tracheal cartilage. The development of tracheal cartilage has not been described in detail. In this study, we aimed to investigate the development pattern and timing of normal tracheal cartilage to better understand the etiology of tracheal anomalies. MATERIALS AND METHODS: The development of tracheal cartilage was examined by studying the trachea in histological sections of 14 healthy human embryos from the Carnegie collection. Two specimens for Carnegie Stages 17-23 (42-60 days of embryological development) were studied. RESULTS: At Carnegie Stages 17-19 (42-51 days), a continuous mesenchymal condensation was observed ventral to the tracheal lumen. At Stages 20 and 21 (51-54 days), this pre-tracheal mesenchyme showed sites of increased condensation indicative of future tracheal rings. Furthermore, growth centers were identified both proximally and distally in the trachea. Characteristic horseshoe shaped tracheal rings were apparent at Carnegie Stages 22 and 23 (54-60 days). CONCLUSIONS: In human embryos, tracheal rings arise from growth centers in the ventral mesenchyme at approximately 51-54 days of embryological development. The observation of proximal and distal growth centers suggests a centripetal growth gradient, potentially contributing to occurrence of complete tracheal ring deformity (CTRD). Although this study shows new insights on tracheal cartilage development, the exact origin of congenital tracheal defects has yet to be elucidated.

Complete Tracheal Ring Deformity. A Translational Genomics Approach to Pathogenesis.

Rationale: Complete tracheal ring deformity (CTRD) is a rare congenital abnormality of unknown etiology characterized by circumferentially continuous or nearly continuous cartilaginous tracheal rings, variable degrees of tracheal stenosis and/or shortening, and/or pulmonary arterial sling anomaly.Objectives: To test the hypothesis that CTRD is caused by inherited or de novo mutations in genes required for normal tracheal development.Methods: CTRD and normal tracheal tissues were examined microscopically to define the tracheal abnormalities present in CTRD. Whole-exome sequencing was performed in children with CTRD and their biological parents ("trio analysis") to identify gene variants in patients with CTRD. Mutations were confirmed by Sanger sequencing, and their potential impact on structure and/or function of encoded proteins was examined using human gene mutation databases. Relevance was further examined by comparison with the effects of targeted deletion of murine homologs important to tracheal development in mice.Measurements and Main Results: The trachealis muscle was absent in all of five patients with CTRD. Exome analysis identified six de novo, three recessive, and multiple compound-heterozygous or rare hemizygous variants in children with CTRD. De novo variants were identified in SHH (Sonic Hedgehog), and inherited variants were identified in HSPG2 (perlecan), ROR2 (receptor tyrosine kinase-like orphan receptor 2), and WLS (Wntless), genes involved in morphogenetic pathways known to mediate tracheoesophageal development in mice.Conclusions: The results of the present study demonstrate that absence of the trachealis muscle is associated with CTRD. Variants predicted to cause disease were identified in genes encoding Hedgehog and Wnt signaling pathway molecules, which are critical to cartilage formation and normal upper airway development in mice.

Claviculotracheopexy for complex airway reconstructions.

PURPOSE: Revision surgery for correcting benign laryngotracheal stenosis is challenging and it gets complicated in patients with comorbidities. To improve results in such cases, we describe a new technique of stabilizing the trachea by splinting it to the clavicle on both sides. METHODS: Retrospective case series. RESULTS: Three patients received claviculotracheopexy to maintain their tracheal static. The surgery offers an immediate and optimal support to an unstable trachea. CONCLUSION: Claviculotracheopexy can be used as a complementary procedure in complex airway reconstructions.

Quantitative Assessment of Regional Dynamic Airway Collapse in Neonates via Retrospectively Respiratory-Gated 1 H Ultrashort Echo Time MRI.

BACKGROUND: Neonatal dynamic tracheal collapse (tracheomalacia, TM) is a common and serious comorbidity in infants, particularly those with chronic lung disease of prematurity (bronchopulmonary dysplasia, BPD) or congenital airway or lung-related conditions such as congenital diaphragmatic hernia (CDH), but the underlying pathology, impact on clinical outcomes, and response to therapy are not well understood. There is a pressing clinical need for an accurate, objective, and safe assessment of neonatal TM. PURPOSE: To use retrospectively respiratory-gated ultrashort echo-time (UTE) MRI to noninvasively analyze moving tracheal anatomy for regional, quantitative evaluation of dynamic airway collapse in quiet-breathing, nonsedated neonates. STUDY TYPE: Prospective. POPULATION/SUBJECTS: Twenty-seven neonatal subjects with varying respiratory morbidities (control, BPD, CDH, abnormal polysomnogram). FIELD STRENGTH/SEQUENCE: High-resolution 3D radial UTE MRI (0.7 mm isotropic) on 1.5T scanner sited in the neonatal intensive care unit. ASSESSMENT: Images were retrospectively respiratory-gated using the motion-modulated time-course of the k-space center. Tracheal surfaces were generated from segmentations of end-expiration/inspiration images and analyzed geometrically along the tracheal length to calculate percent-change in luminal cross-sectional area (A % ) and ratio of minor-to-major diameters at end-expiration (r D,exp ). Geometric results were compared to clinically available bronchoscopic findings (n = 14). STATISTICAL TESTS: Two-sample t-test. RESULTS: Maximum A % significantly identified subjects with/without a bronchoscopic TM diagnosis (with: 46.9 ± 10.0%; without: 27.0 ± 5.8%; P < 0.001), as did minimum r D,exp (with: 0.346 ± 0.146; without: 0.671 ± 0.218; P = 0.008). Subjects with severe BPD exhibited a far larger range of minimum r D,exp than subjects with mild/moderate BPD or controls (0.631 ± 0.222, 0.782 ± 0.075, and 0.776 ± 0.030, respectively), while minimum r D,exp was reduced in CDH subjects (0.331 ± 0.171) compared with controls (P < 0.001). DATA CONCLUSION: Respiratory-gated UTE MRI can quantitatively and safely evaluate neonatal dynamic tracheal collapse, as validated with the clinical standard of bronchoscopy, without requiring invasive procedures, anesthesia, or ionizing radiation. LEVEL OF EVIDENCE: 2 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2019;49:659-667.

The use of expandable metallic airway stent in a baby with tracheomalacia: A case report.

Tracheobronchomalacia is a rare condition in the pediatric age group which may be life-threatening when it occurs. The common form of tracheomalacia is congenital, presenting with wheezing and cough. We report a case of a 65-day-old baby who was treated with non-invasive mechanical ventilation due to respiratory distress since the day of birth. Tracheomalacia was diagnosed based on the physical examination and the thorax computerized tomography (CT) findings. Patient was initially treated with noninvasive positive pressure ventilation and thereafter, fitted with a tracheobronchial conical fully-covered self-expandable nitinol stent. After stent insertion and the respiratory situation of the patient improved, ventilatory weaning and extubation were possible. A careful selection of suitable patients, appropriate stent type and the site, where it has to be placed is mandatory for successful airway stenting. Also, children must be adequately followed-up to prevent the possible life-threatening complications after stent insertion.

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.