Cartilaginous Rings Research Articles

Airway Challenges in a Preterm Neonate with Undiagnosed Complete Tracheal Rings Posted for Surgery

Preterm neonates are defined as those born before 37 weeks. The anatomical features of preterm neonates vary from that of an adult, such that they have a large tongue, an anterior funnel shaped larynx, angled vocal cords and an omega shaped epiglottis. Their physiological development also differ as they have a greater risk for apnoea of prematurity, airflow obstruction, bronchopulmonary dysplasia, low functional residual capacity and decreased transient oxygen tension. Congenital airway anomalies have a prevalence rate of 0.2-1 in 10,000 live births. Congenital Tracheal Stenosis (CTS) caused by complete tracheal rings is one of the rarest forms of all the airway anomalies that occur, which is characterised by presence of complete ‘O’ shaped cartilaginous rings of trachea devoid of a membranous part. The case discussed in the article is that of a day 26 preterm neonate with increasing abdominal distension and failure to thrive. The neonate was posted for an urgent exploratory laparotomy for abdominal decompression and ileostomy. Patient was kept on Continuous Positive Airway Pressure (CPAP) support for four days immediately after birth; however, intubation was never attempted nor required. With a history of respiratory depression and lack of history of previous intubation, difficult airway cart was kept ready prior to surgery. Supraglottic Airway (SGA) devices were at the core of airway rescue in this case of undiagnosed CTS. This case report shows how and why a preparation for difficult airway in preterm neonates is a necessity. It will provide as a guide if a similar case is encountered by the anaesthetist.

Microscopic anatomical, immunohistochemical, and morphometric characterization of the terminal airways of the lung in cetaceans.

The lungs of cetaceans undergo anatomical and physiological adaptations that facilitate extended breath-holding during dives. Here, we present new insights on the ontogeny of the microscopic anatomy of the terminal portion of the airways of the lungs in five cetacean species: the fin whale (Balaenoptera physalus); the sperm whale (Physeter macrocephalus), the Cuvier's beaked whale (Ziphius cavirostris); the bottlenose dolphin (Tursiops truncatus); and the striped dolphin (Stenella coeruleoalba). We (a) studied the histology of the terminal portion of the airways; (b) used immunohistochemistry (IHC) to characterize the muscle fibers with antibodies against smooth muscle (sm-) actin, sm-myosin, and desmin; (c) the innervation of myoelastic sphincters (MESs) with an antibody against neurofilament protein; and (d) defined the diameter of the terminal bronchioles, the diameter and length of the alveoli, the thickness of the septa, the major and minor axis, perimeter and section area of the cartilaginous rings by quantitative morphometric analyses in partially inflated lung tissue. As already reported in the literature, in bottlenose and striped dolphins, a system of MESs was observed in the terminal bronchioles. Immunohistochemistry confirmed the presence of smooth muscle in the terminal bronchioles, alveolar ducts, and alveolar septa in all the examined species. Some neurofilaments were observed close to the MESs in both bottlenose and striped dolphins. In fin, sperm, and Cuvier's beaked whales, we noted a layer of longitudinal smooth muscle going from the terminal bronchioles to the alveolar sacs. The morphometric analysis allowed to quantify the structural differences among cetacean species by ranking them into groups according to the adjusted mean values of the morphometric parameters measured. Our results contribute to the current understanding of the anatomy of the terminal airways of the cetacean lung and the role of the smooth muscle in the alveolar collapse reflex, crucial for prolonged breath-holding diving.

Larygeotrache oseophageal cleft: a rare entity

<p>Larygeotrache oseophageal cleft is a rare anomaly in a newborn presenting with respiratory distress and choking with feeding symptoms identical with oesophageal atresia with or without tracheo-oesophageal fistula .It is an abnormal communication of the larynx and the trachea with the oesophagus occurring during fifth to seventh week of gestation as a result of circoid cartilage failing to fuse dorsally. LTOC varies greatly in anatomical extent and clinical severity; more severe forms in which the some or all of the tracheal cartilaginous rings are incomplete are fatal unless corrected surgically. LTOC occurs in less than 1/10,000 to 1/20,000 live births with slightly male predilection and has a autosomal dominant mode of inheritance. Routine chest X-rays and barium oesophagogram are usually not conclusive but bronchoscopy will delineate anatomy of cleft clearly. We present detailed case report of neonate with respiratory distress and choking on feeding and illustrating maneuvers at endoscopy and subsequent individualized surgical management of child.</p>

Anatomy of the respiratory system in the, “Portrait of a Musician” by Leonardo da Vinci

The object of the research is the painting, Portrait of a Musician’’. Upon closer examination of the painting, we discovered three details. Two have the shape of trachea and bronchi and the third a larynx. By moving the details through the program Paint X we got an image of the larynx, trachea and bronchi. The larynx is presented by thyroid and cricoid cartilage. The characteristic cartilaginous rings are distinguished on the trachea. The right and left main bronchi are also seen. In our opinion, Leonardo da Vinci reflected the elements of the respiratory system in the, Portrait of a Musician’’, thus emphasizing the fact that the bronchi, trachea and larynx are involved in the production of sound.

IMPENDING DANGERS IN PATIENTS WITH TRACHEOMALACIA WITH ANXIETY DISORDER/PTSD

SESSION TITLE: Medical Student/Resident Respiratory Care SESSION TYPE: Med Student/Res Case Rep Postr PRESENTED ON: October 18-21, 2020 INTRODUCTION: Trachea is a D-shaped structure with incomplete cartilaginous rings anteriorly and laterally and straight membranous wall posteriorly. Tracheomalacia is a pathological process that happens due to flaccidity of the supporting cartilage and widening of posterior membranous wall with reduced anterior-posterior airway caliber leading to tracheal collapse. Our case enlightens that adequate control of anxiety symptoms plays an important role in trach management in tracheomalacia patients. CASE PRESENTATION: An 84-year-old man with HTN, COPD, A.fib, HFrEF, PTSD, severe anxiety disorder, h/o CVA with hemorrhagic conversion after tPA, severe L-carotid artery stenosis s/p endarterectomy, stage 1 T1N0M0 SCC of left vocal cord s/p laser resection/XRT, tracheostomy with tracheomalacia. Multiple rapid responses were called because of sudden tachypnea, hypoxemia with cyanosis leading to hypoxic respiratory failure. After each episode he gets transferred to ICU for mechanical ventilation management. Infections were ruled out in most of the case, mucous plugs rarely blocked the tracheostomy tube. Almost all episodes occurred while he was off his anxiety medications. DISCUSSION: The thought of underlying cause leading to hypoxemic respiratory failure was whenever he felt anxious/agitated he flexed his neck and together with the collapse of tracheal wall over the opening of tracheostomy tube this prevented air flow. This is similar to mucus plugs blocking the tube opening. Once his anxiety is well controlled, he relaxes and improves air entry through Tracheostomy tube. CONCLUSIONS: In tracheostomy dependent tracheomalacia patients with anxiety disorder; it is of utmost importance to control anxiety symptoms. Extreme anxiety/agitation from PTSD and anxiety disorder along with flexion of the neck, can compromise air entry into tracheostomy tube, which can result in hypoxemic respiratory failure and within minutes one can have clinical deterioration with death. Reference #1: Carden KA, Boiselle PM, Waltz DA, Ernst A. Tracheomalacia and tracheobronchomalacia in children and adults: an in-depth review. chest. 2005 Mar.127(3):984-1005 DISCLOSURES: No relevant relationships by Moses Bachan, source=Web Response No relevant relationships by Zinobia Khan, source=Web Response No relevant relationships by swetha Nadella, source=Web Response No relevant relationships by Robert Siegel, source=Web Response

REFRACTORY RELAPSING POLYCHONDRITIS: WHAT SHOULD A PULMONOLOGIST DO?

SESSION TITLE: Fellows Pulmonary Manifestations of Systemic Disease Posters SESSION TYPE: Fellow Case Report Posters PRESENTED ON: October 18-21, 2020 INTRODUCTION: Relapsing polychondritis (RP) is a rare systemic disease characterized by recurrent episodes of inflammation, which can result in degeneration and deformation of the cartilage of the ears, nose, larynx, and tracheobronchial tree. The incidence of RP is 0.7-4.5 per million people with a 20-50% prevalence of respiratory impairment. Airway involvement portends a poor prognosis in this disease, and reporting of cases is beneficial to educate pulmonologists about the importance of a multidisciplinary team in managing patients with RP. CASE PRESENTATION: A 23-year-old female with relapsing polychondritis, subglottic stenosis, and tracheal stenosis status post tracheostomy on chronic immunosuppression with dapsone, mycophenolate, and prednisone presented with worsening shortness of breath despite steroid injections for subglottic stenosis. CT chest demonstrated tracheal narrowing with significant wall thickening of the bilateral mainstem bronchi. She underwent bronchoscopy, which demonstrated erythema in the trachea with loss of the cartilaginous rings, mucosal thickening extending to the bilateral mainstem bronchi including LC2 and RC1, and normal distal bronchi. Even with PEEP, she had complete collapse of the bilateral mainstem bronchi with expiration. Her prednisone dose was increased, but her shortness of breath persisted. Her FEV1 was 46% predicted and FEV1/FVC was 49% predicted on pulmonary function testing. Due to worsening dyspnea at rest, she underwent repeat bronchoscopy 3 months later which demonstrated slightly worsening of inflammation in her mainstem bronchi. She was started on Actemra by rheumatology with subjective improvement in her shortness of breath within 3 weeks. Polysomnography was ordered to try to qualify her for nocturnal non-invasive ventilation. After discussion with otolaryngology, it was decided to not pursue further bronchoscopy for airway evaluation due to concern that bronchoscopy would cause worsening of inflammation of her airways over time. DISCUSSION: Management of refractory RP is challenging for the pulmonologist because there are not evidence based guidelines to follow. Based on expert opinion, pulmonary function testing with flow volume loops is recommended in all patients with RP to characterize airway involvement in symptomatic patients. For the treatment of tracheomalacia, intralesional corticosteroid injections and tracheostomy can be warranted. Tracheobronchial stenting can be helpful, but it also risks worsening of airway inflammation. Thus, a team-based approach is helpful to weigh the risks and benefits of treatment options to determine the best care for the patient with worsening symptoms. CONCLUSIONS: Relapsing polychondritis is a rare disease which is challenging to treat due to a lack of evidence based guidelines. Leveraging the expertise of otolaryngology, pulmonology, and rheumatology is helpful to guide symptomatic management. Reference #1: Lekpa FK, Chevalier X. Refractory relapsing polychondritis: challenges and solutions. Open Access Rheumatol. 2018;10:1-11. Published 2018 Jan 9. doi:10.2147/OARRR.S142892 Reference #2: Ernst A, Rafeq S, Boiselle P, et al. Relapsing polychondritis and airway involvement. Chest. 2009;135(4):1024-1030. doi:10.1378/chest.08-1180 Reference #3: de Montmollin N, Dusser D, Lorut C, et al. Tracheobronchial involvement of relapsing polychondritis. Autoimmun Rev. 2019;18(9):102353. doi:10.1016/j.autrev.2019.102353 DISCLOSURES: No relevant relationships by Maureen McElligott, source=Web Response

Tracheomalacia due to trachea compression related to benign goiter

Tracheomalacia can result from long-standing compression by a large goiter. The cartilaginous rings of the trachea may be weakened or destroyed by long-standing compression, causing loss of structural support. Tracheomalacia after resectioning of benign goiter compressing trachea was an important issue. It has extended the time of mechanical ventilation, increased the risk of failure extubating and mortality. Descriptive and prospective study. From November 2014 to January 2017, we have collected 102 patients who had benign goiter compressing trachea and had thyroidectomy. Tracheomalacia was diagnosed and managed intra and postoperatively. Recognition of women accounted for the majority of 81.4%. The average age was 54.5 years old and the average duration of goiter was 5 years. The patients were hospitalized with the main symptom of dysphagia accounting for 21.6% and difficulty breathing when lying down was 16.7%. On CT scan, the average Goiter was 270g, the average narrow airway diameter was 8.4 mm, of which 12.7% of patients had narrow tracheal diameter <5mm. The rate of tracheomalacia was 4.9%. There were statistically significant differences between the 2 groups with and without tracheomalacia: elderly patients (p = 0.041); goiter long-standing time (p = 0.07); symptoms of positional dyspnea on lying (p = 0.003) and tracheal diameter compressed (p = 0.001). Tracheomalacia should be noted in patients older than 65 years old, goiter exist longer than 5 years and goiter is over 200g.

Reinforcement of the larynx and trachea in echolocating and non-echolocating bats.

The synchronization of flight mechanics with respiration and echolocation call emission by bats, while economizing these behaviors, presumably puts compressive loads on the cartilaginous rings that hold open the respiratory tract. Previous work has shown that during postnatal development of Artibeus jamaicensis (Phyllostomidae), the onset of adult echolocation call emission rate coincides with calcification of the larynx, and the development of flight coincides with tracheal ring calcification. In the present study, I assessed the level of reinforcement of the respiratory system in 13 bat species representing six families that use stereotypical modes of echolocation (i.e. duty cycle % and intensity). Using computed tomography, the degree of mineralization or ossification of the tracheal rings, cricoid, thyroid and arytenoid cartilages were determined for non-echolocators, tongue clicking, low-duty cycle low-intensity, low-duty cycle high-intensity, and high-duty cycle high-intensity echolocating bats. While all bats had evidence of cervical tracheal ring mineralization, about half the species had evidence of thoracic tracheal ring calcification. Larger bats (Phyllostomus hastatus and Pterpodidae sp.) exhibited more extensive tracheal ring mineralization, suggesting an underlying cause independent of laryngeal echolocation. Within most of the laryngeally echolocating species, the degree of mineralization or ossification of the larynx was dependent on the mode of echolocation system used. Low-duty cycle low-intensity bats had extensively mineralized cricoids, and zero to very minor mineralization of the thyroids and arytenoids. Low-duty cycle high-intensity bats had extensively mineralized cricoids, and patches of thyroid and arytenoid mineralization. The high-duty cycle high-intensity rhinolophids and hipposiderid had extensively ossified cricoids, large patches of ossification on the thyroids, and heavily ossified arytenoids. The high-duty cycle high-intensity echolocator, Pteronotus parnellii, had mineralization patterns and laryngeal morphology very similar to the other low-duty cycle high-intensity mormoopid species, perhaps suggesting relatively recent evolution of high-duty cycle echolocation in P. parnellii compared with the Old World high-duty cycle echolocators (Rhinolophidae and Hipposideridae). All laryngeal echolocators exhibited mineralized or ossified lateral expansions of the cricoid for articulation with the inferior horn of the thyroid, these were most prominent in the high-duty cycle high-intensity rhinolophids and hipposiderid, and least prominent in the low-duty cycle low-intensity echolocators. The non-laryngeal echolocators had extensively ossified cricoid and thyroid cartilages, and no evidence of mineralization/ossification of the arytenoids or lateral expansions of the cricoid. While the non-echolocators had extensive ossification of the larynx, it was inconsistent with that seen in the laryngeal echolocators.

The Histology of the Trachea in Dogs

The trachea was collected from apparently normal six adult dogs of spitz breed aged between 2-4 years of age from the post-mortem of the Veterinary Pathology department. The aim of the study was to observe the histological details of the trachea in the spitz breed of dogs. The tracheal wall consisted of the mucosa, submucosa, hyaline cartilage, and adventitia. Tracheal mucosa was lined by a pseudostratified ciliated columnar epithelium with mucous secreting goblet cell and basal cells. Lamina propria was made up of loose connective tissue and contained some alveolar mucous glands. Muscularis mucosa was a thin layer with smooth muscle fibers arranged in a dispersed manner. The submucosa contained loose connective tissue with numerous mucous secreting tubule – acinar submucosal gland and was found related to the perichondrium of cartilaginous rings. The dense fibroelastic tissue was found between the cartilaginous rings. The cartilaginous rings were flattened in cross-section. Thin tunica adventitia of loose connective tissue and covered the cartilaginous rings. Trachealis muscle was found.

Imaging Evaluation of Tracheobronchial Injuries.

Tracheobronchial injuries are a rare but potentially life-threatening cause of respiratory insufficiency, with high mortality rates. For patients with potentially survivable tracheobronchial injuries, imaging in the acute setting plays a key role in demonstrating the injuries and associated complications. The radiologist can improve outcomes by understanding typical injury patterns according to injury mechanism and the influence that imaging findings may have on treatment decisions. Chest radiography and cervical and thoracic CT are the mainstays of imaging in the acute setting and in follow-up, often as part of a whole-body trauma imaging series. The authors first consider the influence of normal tracheobronchial anatomy with regard to protective features, such as cartilaginous rings. They also discuss inherent points of vulnerability, such as points of relative fixation at the carina. A framework is then provided for understanding the typical distribution and morphology of tracheobronchial injuries according to cause. This includes penetrating, iatrogenic, and blunt force mechanisms, with consideration of potential complications. The authors highlight treatment strategies that require multidisciplinary collaboration, such as ventilation, minimizing injuries, and defining optimal surgical or nonsurgical treatment. ©RSNA, 2020.

Clinical and structural aspects of tracheal stenosis and a novel embryological hypothesis of left pulmonary artery sling.

To identify the imaging features peculiar to congenital tracheal stenosis (CTS) complicated with left pulmonary artery sling (LPAS) with the aim of presenting a hypothesis of tracheal stenosis embryology in LPAS. We retrospectively reviewed CTS patients (with complete cartilaginous rings) admitted between April 2010 and July 2018. All the patients were classified into the LPAS or non-LPAS group, and their clinical characteristics and qualitative variables on computed tomography (CT) imaging were compared. Of the 72 patients enrolled, 61 had bilateral lungs. Among the bilateral lung patients, 26 (43%) had LPAS. The tracheal bifurcation was significantly deeper, the stenotic region was longer, and the bronchial angle (especially in the right) was wider, in the LPAS group. The cut-off values for the thoracic vertebral level at the tracheal bifurcation (>4.8), subcarinal angle (>118.1), and right bronchial angle (>61.9) were useful for diagnosing suspected cases of LPAS. In the time-dependent course, LPAS complicated with a congenital heart defect was a statistically significant risk factor of respiratory symptoms (hazard ratio, 3.01; 95% confidence interval, 1.23-7.37; P = .02). The CT findings described here should immediately raise suspicion of LPAS on chest X-ray and also suggest tracheal "squeezing and milking" by the surrounding vessels in the embryo. Patients with LPAS complicated with a heart defect should be followed carefully to determine the optimal timing of intervention.

Morphological study of larynx, trachea, and lungs of Didelphis marsupialis (LINNAEUS, 1758)

Background and Aim:From a biomedical point of view, the value of marsupials as a model of primitive mammals is indisputable. Among its species, the possum is a model that allows the study of the ontogeny of different organic systems, as well as their physiological aspects. The relevance of anatomical, functional, evolutionary, and phylogenetic study of marsupials for the development of comparative morphology is extensively documented in the literature. However, there are still many aspects to be further evaluated, as the anatomy and histology of the respiratory tract of this species. The aim of this study was to describe the morphology of the larynx, trachea, and lungs of Didelphis marsupialis.Materials and Methods:Five adult male animals were donated to the Comparative Animal Anatomy Laboratory – LAAC/CCAA-UFMA, for morphological studies. Specimens were washed in running water to perform biometrics. Then, they were fixed with 10% formaldehyde solution. After the fixation period, the specimens were positioned in dorsal decubitus position, for dissection of the respiratory system organs, by opening the ventral region of the neck and thoracic cavity, with subsequent removal of the pectoral muscles, ribs, and sternum. For histological analysis, fragments of 1 cm2 of the larynx (epiglottis and thyroid cartilages), trachea, and lungs were collected and fixed in 10% formaldehyde solution. Right after fixation, the fragments were dehydrated in increasing concentrations of ethyl alcohol (70, 80, 95, and 100%), diaphanized in xylene, embedded in paraffin, and sectioned into thin slices of 5 μm using a microtome. Sections were stained using the hematoxylin and eosin technique.Results:Anatomically, the larynx starts right after the pharynx. It consisted of four cartilages: Epiglottis, cricoid, thyroid, and arytenoid. The trachea was made of dorsally incomplete cartilaginous rings. At the entrance of the thoracic cavity, it bifurcated into the left and right main bronchus. The left lung was smaller than the right lung, with two lobes (cranial and caudal). The right lung presents the cranial, middle, caudal, and accessory lobes. Histologically, the epiglottis consisted of elastic cartilage and is covered by a non-keratinized stratified squamous epithelium. Thyroid cartilage is made of hyaline cartilage covered by smooth muscle. The trachea presents hyaline cartilage, with ciliated pseudo-stratified epithelium, serous glands, isogenic groups of chondrocytes, and perichondrium. The lung consisted of bronchi, bronchioles, and alveoli, also presenting blood vessels and arteries.Conclusion:Morphologically, the larynx, trachea, and lungs of D. marsupialis were similar to those of the other Didelphids described in the literature.

The deltopectoral flap in the management of tracheostomal stenosis post laryngectomy and radiotherapy

Tracheostomal stenosis is a distressing complication with a high incidence rate post laryngectomy. We aimed to assess the deltopectoral flap (DPF) for tracheostomal stenosis correction in irradiated patients. Six patients with tracheostomal stenosis, 3 of whom developed restenosis after prior use of local flaps, were managed using a DPF to reconstruct the defect following a vertical incision release of the stenotic band down to the inferior tracheal cartilaginous ring. Healing absence of restenosis, alleviation of the symptoms of difficulty in breathing and clearance of secretions were considered a successful composite endpoint. Over a median follow-up period of 11 months all patients maintained patency, and symptoms of difficulty in breathing and clearing of secretions were alleviated. The deltopectoral flap is a rapid, reliable flap for the management of tracheostomal stenosis in irradiated patients. It brings well-vascularised tissue into the site of reconstruction and, in the short term, stomal patency and symptom relief were achieved.

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.

Finite element simulation of human trachea: Normal vs. surgically treated and scaffold implanted cases

Trachea experiences mechanical loads under physiological conditions. Surgery and tissue engineering change its mechanical conditions and may cause remodeling or damage. Here, we mechanically simulated one healthy trachea (from a 53-year-old brain-dead man) and as two examples, evaluated the impacts of surgery and scaffold implantation. Before patient's death, CT-scanning was performed at two respiratory pressures (0 and + 40 cm H2O for constructing 3D tracheal geometry at zero-stress state and model validation, respectively). After harvesting trachea, MRI, mechanical testing and hyperelastic modeling of tracheal tissues (cartilage, smooth muscle, and connective tissue) were performed. We simulated tracheal deformation and stress distribution under three conditions, including normal, 30%-resection of tracheal length and anastomosis (surgery) or its substitution with a cylindrical scaffold. In all models, the greatest stresses were produced in cartilaginous rings. Surgery-related extension reduced the physiologic cross-sectional deformability and increased stress levels in response to respiratory pressures, compared to normal trachea. For instance, maximum von-Mises stress in normal and operated trachea reached 355 kPa and 3.228 MPa, respectively. Scaffold was less deformable than normal trachea, though stress levels in both models were relatively close. This study provides an insight into the mechanics of human trachea and the impacts of surgery or scaffold implantation.

Congenital Segmental Absence of Tracheal Rings in a Kitten

Congenital anomalies of the trachea are rare in cats. This article reports segmental absence of tracheal cartilage rings in a kitten. An 8-month-old female kitten was presented with a history of weight loss and respiratory distress for 2 months. Radiographs of the thorax demonstrated a large air-filled sac suggestive of pneumomediastinum. No cartilaginous structures were evident radiographically over the caudal portion of the trachea. At necropsy examination, approximately 2cm from the carina, a 3cm segment of the trachea lacked cartilaginous rings. The clinical and morphological features of this lesion were similar to those described in human and canine cases of congenital segmental absence of tracheal rings.

DOZ047.99: A unique case of ‘esophageal trachea’ requiring a multistep sequential surgical reconstruction

Abstract Introduction Communicating bronchopulmonary foregut malformations (CBPFMs) have been defined by Srikanth et al. in 1992 as a fistula between a portion of respiratory tissue and esophagus/stomach. Four types of CBPFMs have been described, none of those contemplating a complete communication between the distal trachea and esophagus. Case Report This study reports a case of a full-term neonate presenting with a VACTERL association and a tracheoesophageal malformation characterized by the presence of a long common duct including both the middle esophagus and distal trachea, which consists in esophageal tissue, without any cartilaginous rings 3–4 cm above the carina. A few days after birth, the esophagus and trachea have been surgically separated, keeping the common duct on the tracheal side and creating a residual long-gap esophageal atresia (LGEA). The resulting severe tracheomalacia has been simultaneously treated by posterior splinting using an autologous pericardium patch, as well as by anterior aortopexy. A terminal esophagostomy and a gastrostomy have been created to postpone esophageal reconstruction. Since the age of 18 months, delayed repair of LGEA has been performed by using a multistep strategy consisting of a combination of Kimura extrathoracic esophageal elongations and distal stump Foker external traction. Since no cartilaginous rings were present, refractory tracheomalacia has been further treated by a tracheoplasty through a combined median sternotomy and tracheoscopy approach at the age of 3 years by using a semitubular rigid Gore-Tex® prosthesis for an anterior external stenting. Today, 9 months after last surgery, complete weaning from respiratory support has been stably achieved, as well as full oral feeding. Conclusions This is the first description of an ‘esophageal trachea’, which may be considered as a new anatomic variant of CBPFMs. Multidisciplinary medical and surgical expertise was needed to manage this particular case, in order to properly plan multiple sequential surgical approaches. Native esophageal reconstruction should always be considered, even because colonic or gastric transposition might further affect severe tracheomalacia, resulting in more challenging treatment.

DOZ047.66: Thoracoscopic posterior tracheopexy during primary esophageal atresia repair

Abstract Background Esophageal atresia (EA) is usually accompanied by some form of tracheomalacia. During the early phases in life, excessive dynamic collapse of the trachea can cause a wide spectrum of symptoms ranging from mild complaints to apparent life-threatening events (ALTE’s). Therapeutic strategies for severe tracheomalacia include aortopexy to lift the anterior weakened cartilaginous rings or posterior tracheopexy of the floppy membranous tracheal intrusion. Earlier we have introduced a new approach in which the posterior tracheopexy is performed directly during primary thoracoscopic correction of EA. Methods In the period 2017–2018, all consecutive EA patients (27) underwent a rigid tracheobronchoscopic evaluation during induction of anesthesia prior to the thoracoscopic EA repair. Tracheomalacia was diagnosed in 11 patients. During the subsequent thoracoscopic procedure, the posterior tracheal membrane was fixed to the anterior longitudinal spinal ligament with nonabsorbable sutures. The esophageal ends were then mobilized toward the right hemithorax and anastomosed. Results On preoperative RTB, six patients had a severe (66–99%) mid tracheal collapse and five patients had a moderate (33–66%) collapse. Thoracoscopic posterior tracheopexy with on to three sutures was possible in all 11 patients, prior to the formation of the esophageal anastomosis. Median time per suture was 6 minutes (range: 4–12 minutes). All operative procedures were uneventful. A median follow-up of 10 months (range: 2–22 months) revealed that eight patients recovered without any respiratory symptoms, one patient had respiratory symptoms caused by a suture granuloma that was removed by bronchoscopy, one patient had a respiratory syncytial virus bronchiolitis and one patient had a rhinovirus infection. None of the patients experienced any ALTE’s. Conclusion Eleven patients have been treated by thoracoscopic posterior tracheopexy during primary EA repair. This technique could prevent potentially deleterious sequelae of moderate to severe tracheomalacia that may complicate the lives of EA patients. Also, a second, sometimes complex surgical procedure can be prevented as the posterior tracheopexy is performed during the primary thoracoscopic EA correction.

Studying airflow structures in periodic cylindrical hills of human tracheal cartilaginous rings

The objective of this study is to assess tracheobronchial flow features with the cartilaginous rings during a light exercising. Tracheobronchial is part of human’s body airway system that carries oxygen-rich air to human’s lungs as well as takes carbon dioxide out of the human’s lungs. Consequently, evaluation of the flow structures in tracheobronchial is important to support diagnosis of tracheal disorders. Computational Fluid Dynamics (CFD) allows evaluating effectiveness of tracheal cartilage rings in human body under different configurations. This study utilizes Large Eddy Simulation (LES) to model an anatomically-based human large conducting airway model with and without cartilaginous rings at the breathing conditions at Reynolds number of 5,176 in trachea region. It is observed that small recirculating areas shaped between rings cavities. While these recirculating areas are decaying, similar to periodic 2D-hills, the cartilaginous rings contribute to the construction of a vortical flow structure in the main flow. The separated vortically-shaped zone creates a wake in the flow and passes inside of the next ring cavity and disturb its boundary layer. At last, the small recirculation flow impinges onto tracheal wall. The outcome of this impinge flow is a latitudinal rotating flow perpendicular to the main flow in a cavity between the two cartilaginous rings crest which appear and disappear within a hundredth of a second. Kelvin-Helmholtz instability is observed in trachea caused by shear flow created behind of interaction between these flow structures near to tracheal wavy wall and main flow. A comparison of the results between a smooth wall model named simplified model and a rough wall model named modified model shows that these structures do not exist in simplified model, which is common in modeling tracheobronchial flow. This study proposes to consider macro surface roughness to account for the separating and rotating instantaneous flow structures. Finally, solving trachea airflow with its cartilages can become one of major issues in measuring the validity and capability of solving flow in developing types of sub-grid scale models as a turbulence studies benchmark.

Development of the chondrocranium of two caiman species, Caiman latirostris and Caiman yacare.

Little is known about the embryonic development and variation of the chondrocranium in Crocodylia and there are no works on any Caiman species. Due to the importance of cranial features in the systematics of this clade, investigating the development of the skull in embryonic stages is essential. In this study, we present for the first time the development of the cartilaginous skull of two extant Caiman species. Anatomical descriptions of the embryonic chondrocranium of Caiman latirostris and Caimanyacare were made, paying special attention to their inter- and intraspecific variation. For this purpose, pre-hatching ontogenetic cranial series of these two caiman species were prepared with a double staining and diaphanization technique. The main differences with other crocodylian species were observed in the palatoquadrate, and interspecific variation within the genus was recorded in the hyobranchial apparatus and larynx. Some characters may be distinctive of Caiman (posterior and ventral surface of the otic process of the palatoquadrate articulated with the dorsal process of the columella auris, and otic process articulated with the lateral wall of the auditory capsule), Alligatoridae (presence of an epiphanial foramen) or C. latirostris and C.yacare (Corpus hyoidei with different number and position of foramina and different shapes of its anterior contour and anterior and posterior notch, different degrees of broadening of the distal end of the Cornu branchiale I, and presence/absence of a notch in the posteroventral surface of the cricoid). Homologies of the elements belonging to the hyobranchial apparatus could not be confirmed. As in other tetrapods the trachea consists of incomplete cartilaginous rings. Morphological changes and dissimilarities found in this study are useful as a context to start studying phylogenetic constraints. Moreover, in a heterochronic context, variations may be involved.