Additive manufacturing or 3D printing applying polycaprolactone (PCL)-based medical devices represents an important branch of tissue engineering, where the sterilization method is a key process for further safe application in vitro and in vivo. In this study, the authors intend to access the most suitable gamma radiation conditions to sterilize PCL-based scaffolds in a preliminary biocompatibility assessment, envisioning future studies for airway obstruction conditions. Three radiation levels were considered, 25 kGy, 35 kGy and 45 kGy, and evaluated as regards their cyto- and biocompatibility. All three groups presented biocompatible properties, indicating an adequate sterility condition. As for the cytocompatibility analysis, devices sterilized with 35 kGy and 45 kGy showed better results, with the 45 kGy showing overall improved outcomes. This study allowed the selection of the most suitable sterilization condition for PCL-based scaffolds, aiming at immediate future assays, by applying 3D-customized printing techniques to specific airway obstruction lesions of the trachea.

Tracheobronchial leiomyoma is a rare tumor of the airway. They arise from the lower respiratory tract tissue of the bronchi, trachea, and lung. Symptomatology is based on the degree of endoluminal bronchial obstruction, and surgical resection is generally the mainstay of treatment. We present the case of a 33-year-old male who suffered from chronic cough and breathlessness for two years caused by large endobronchial leiomyoma diagnosed by preoperative biopsy. The tumor was surgically resected through bronchotomy and complete preservation of the lung parenchyma. We stress the importance of a definitive preoperative diagnosis of this rare tumor to employ lung preserving surgical techniques.

Mediastinal masses can compress the respiratory or cardiovascular system, especially when anteriorly located. Obtaining histological material for diagnosis poses a challenge due to the major risk of cardiorespiratory collapse following anesthetic procedure. Our case shows the utility of rescue with venovenous extracorporeal membrane oxygenation (VV-ECMO) after occurrence of such an event and demonstrates the feasibility of administering chemotherapy during VV-ECMO. A 4-year-old boy was referred to the pediatric oncology clinic of our hospital after a large mediastinal mass was observed on chest radiography ordered due to persistent cough. Computed tomography of the thorax revealed a 100×85 mm mass in the anterior mediastinum, surrounding the heart, and showed that there was compression to the trachea, bronchiole, and vascular structures. Percutaneous needle biopsy accompanied by ultrasonography was planned for diagnostic purposes. Low-dose ketamine and midazolam were administered for procedural sedation in the operating room. After the biopsy procedure, the patient developed sudden airway obstruction requiring intubation. Despite 100% oxygen support with a mechanical ventilator, pulse oximeter saturation remained below 80%. Chest X-ray revealed total collapse of the left lung, and the patient's oxygen saturation did not increase with selective left bronchial intubation. Bi-caval dual-lumen ECMO cannula was placed in the internal jugular vein and VV-ECMO was initiated, resulting in swift improvement in hypoxemia. The patients's anterior mediastinal mass shrank rapidly and left lung improved with chemotherapy. The patient remained on ECMO for a total of 9 days and was extubated 2 days after ECMO termination, followed by discharge to the pediatric oncology ward on the 20th day of pediatric intensive care unit stay. It is well known that large, anteriorly-located mediastinal masses carry a considerable risk of causing cardio-pulmonary collapse during procedures involving anesthesia. All life-saving options, including emergency ECMO, should be available before any planned invasive procedures in these patients.

Aerodigestive obstruction due to cricoid hypertrophy is a rare and potentially life-threatening condition. We present a two-year-old female patient who displayed repetitive respiratory infections, swallowing disorder, and malnutrition without any eye signs or symptoms of airway alterations. We described a patient with aerodigestive obstruction generating a marked narrowing of the trachea immediately below the larynx due to severe thickening of the cricoid cartilage. She was successfully treated with surgery, and the clinical and radiological features of this condition are presented here with a review of the literature.

Total airway obstruction in thyroid cancer is rare and has high morbidity and mortality. Airway management in such cases is challenging, especially in cases in which thyroid masses cannot be totally resected. It is important to choose the appropriate airway treatment modality. Currently, therapeutic rigid bronchoscopy procedures and endoluminal lasers, as well as airway stent insertion, are a management modality of near-total malignant airway obstruction. We report a rigid bronchoscopy procedure combined with laser and Y-stent silicone insertion in thyroid cancer with extension infiltration, as well as compression in the trachea covering the subglottic tracheal area up to the main carina and tracheo-bronchomalacia, manifesting as acute respiratory failure.

Laryngotracheal stenosis (LTS) is a narrowing of the upper airway between the larynx and the trachea with potentially devastating consequences, including respiratory failure, cardiopulmonary arrest, and death. The upper airway is comprised of the larynx, glottis, subglottic region, and trachea. The trachea is a cylindrical-shaped tube with an anterior cartilaginous wall formed by c-shaped rings and a posterior membranous wall. The trachea branches off into the right and left mainstem bronchi at the carina, which is at the level of the fourth thoracic vertebra (T4). Laryngeal stenosis may occur as a result of trauma, related to endotracheal intubation or due to a neoplasm, autoimmune, or infectious process. It can be asymptomatic, or can lead to symptoms of upper airway obstruction. Laryngeal narrowing from any cause calls for a multidisciplinary approach to management, including, but not limited to, pulmonologists, intensivists, otolaryngologists, and gastroenterologists as well as speech and language pathologists, and cardiothoracic surgeons. The determination of the etiology of the laryngotracheal stenosis is critical as it can drive the management and provide prognostic information to the patient.

Extracorporeal membrane oxygenation (ECMO) assists blood circulation and gas exchange via a heart-lung machine. ECMO is used mainly in intensive care units as bridging therapy until heart and respiratory failure can be addressed or until transplantation can be performed. ECMO is sometimes used during surgery under general anaesthesia, depending on the patient's underlying diseases and the nature of the operation. If the oxygen supply and carbon dioxide removal capacity are limited, venovenous (VV)-ECMO can be helpful. Here, we describe the use of VV-ECMO for surgical resection of an endotracheal mass through rigid bronchoscopy in a patient who developed decompensating dyspnoea due to central airway obstruction (CAO).

Neck tumors in newborns are very rare. Teratomas usually include all three germ cell layers, as well as tissues that are not native to the anatomic site of genesis. Teratomas of the head and neck make up a smaller percentage of congenital teratomas. Because of the external compression that oropharyngeal or neck masses produce, they can cause serious airway obstruction. In addition, the larynx or trachea may have an underlying lesion. We presented a mature, 1-day-old newborn with an isolated giant neck tumor and difficulty breathing. The intubation was successfully done and the entire mass was completely removed. Early neonatal life is explored to emphasize this challenge briefly with several interesting instances, including prenatal diagnosis, therapeutic alternatives, and ex-utero intrapartum therapy (EXIT) techniques.

Rosai-Dorfman disease (RDD) is a non-malignant condition mainly manifesting as a proliferation of histiocytes in lymph nodes. Endotracheal RDD (ERDD) with an acute onset presentation is extremely rare. There are few case reports of ERDD mainly concerning its pathology, diagnostics and bronchoscopic treatment, without providing sufficient clinical information from a comprehensive perspective. As a novel and challenging technique, tracheal resection and reconstruction (TRR) with spontaneous-ventilation video-assisted thoracoscopic surgery (SV-VATS) has been reported as feasible and safe in highly selected patients, but few centres have shared their experience with this approach. This case-based discussion includes not only practical issues in the management of a life-threatening ERDD patient, but also specialists' views on the management of acute obstructive airway, and the surgeons' reflection on TRR with SV-VATS.

The upper airway consists of the nasal cavities, oral cavity, pharynx, and larynx. The pharynx is further subdivided into the nasopharynx, oropharynx, and hypopharynx. The larynx is divided into three regions, dependent on their relationship to the vocal cords (glottis). These areas are the supraglottis, glottis, and subglottis. The supraglottis consists of the epiglottis, the arytenoids, the aryepiglottic folds, the false cords, and the ventricles. The subglottis is the subregion just below the free edge of the vocal cords to the inferior margin of the cricoid. The narrowest part of an adult airway is the glottis. The narrowest part of a pediatric airway is the cricoid.  Upper airway obstruction varies from narrowing to partial or complete occlusion of any of these anatomic structures, potentially leading to a compromise in ventilation. Given the urgency related to this issue, it is crucial that healthcare professionals fully understand and appreciate the signs and symptoms that indicate upper airway obstruction. When forming a differential diagnosis for upper airway obstruction, it is important to determine the level at which the obstruction is occurring. A vital clinical sign is noisy breathing, which can be described as 'stertor' or 'stridor'. ‘Stertor’ is noisy breathing which occurs above the larynx. ‘Stridor’ is noisy breathing that occurs at the level of the larynx or below.  Stridor can be further subdivided as inspiratory (level of the supraglottis), expiratory (level of the glottis), and biphasic (level of the subglottis or trachea). Upper airway obstruction can be partial or complete. A partial obstruction can be chronic or acute, therefore it is crucial to take a good history and perform an efficient and comprehensive exam to determine the etiology of the obstruction and therefore the urgency of subsequent management. Left untreated, upper airway obstruction can have significant long-term or fatal effects. 

Tracheobronchopathia Osteochondroplastica (TO) is an extremely rare condition characterized by the presence of nodules made of bone and cartilage within the submucosa of the tracheobronchial wall. These protuberant nodules inside the trachea and bronchi can lead to airway obstruction, resulting in patients who experience recurrent respiratory systems and infections. The exact etiology is unknown. The mean age of diagnosis is in the 5th - 6th decades of life. TO is often confused with other diagnoses, especially asthma. We report a 41-year-old female who presented with intermittent exertional dyspnea for 10 years. Workups, including pulmonary function test, CT chest, and most importantly, flexible bronchoscopy, aided in the appropriate diagnosis. The unique feature observed during bronchoscopy is the sparing of the posterior wall of the trachea and bronchi.

Tracheal sound sensors provide multiple respiratory signals that are valuable for studying upper airway characteristics. This chapter reviews the original work and ongoing research on tracheal sound analysis in relation to upper airway obstruction during sleep. Past and current research suggest that being associated with other sleep study recording sensors and advanced signal processing techniques, tracheal sound analysis can extensively contribute to the diagnosis and assessment of sleep-disordered breathing.

Subglottic stenosis can be defined as the narrowing of the upper airway, which lies between the vocal folds and the lower border of the cricoid cartilage. Normally, the subglottic lumen is 4.5 mm to 5.5 mm in a full-term neonate, while a 3.5 mm lumen is normal in a premature neonate. A subglottic diameter of 4 mm or less in a full-term neonate is considered as narrow. Causes of subglottic stenosis can be either congenital, acquired, or idiopathic. In congenital subglottic stenosis, there is no history of endotracheal intubation or any other acquired cause of the stenosis. A rare genetic disorder called Pallister Killian syndrome is caused by tetrasomy 12p mosaicism and presents phenotypically with multisystem morphologic defects involving the respiratory system and progressive subglottic stenosis.[1]  Acquired subglottic stenosis is more common than congenital due to the introduction of prolonged intubation in the 1960s, and it does not improve with time.[2] Avoidance of tracheostomy in patients with subglottic stenosis is paramount and this is possible by advances in balloon dilation and endoscopic cricoid split techniques. Tracheostomy decannulation can be more likely with laryngotracheal reconstruction and cricotracheal resection.[3] Idiopathic subglottic stenosis is very rare and is characterized by circumferential stenosis in the subglottic region and upper trachea. A single-stage laryngotracheal resection and reconstruction are the preferred definitive treatment for idiopathic subglottic stenosis.[2] Signs and symptoms range from recurrent croup and exertional stridor to complete airflow obstruction requiring tracheostomy.[4]  Symptoms of idiopathic subglottic stenosis can be misinterpreted as asthma. When asthma medication fails to treat symptoms, the patient is diagnosed with an endoscopic evaluation. Depending on the severity of the stenosis, the treatment can involve Grillo’s technique, cricoplasty, or a combination of resection and enlargement techniques using rib cartilage grafts.[5]

Basic airway management in both the pediatric and adult populations includes assessing and managing airway patency, oxygen delivery, and ventilation. All efforts should be taken to maintain a patient’s airway via non-invasive methodology unless indications for invasive airway management are apparent. Non-invasive airway supplementation includes passive oxygenation (nasal cannula, non-rebreather, among others), bag-valve-mask (BVM), non-invasive positive pressure ventilation (BVM with positive-pressure valve, CPAP, BIPAP), and supraglottic airways (King Tube, Laryngeal Mask Airway, among others). Invasive airway management involves establishing a secure airway and placing patients on a ventilator via intubation (nasal or endotracheal), needle jet ventilation (in pediatric patients younger than 8 years old, cricothyroidotomy in adults and in pediatric patients older than 8 years old), and tracheostomy.[1][2][3] Proper airway management begins by visually evaluating the patient for any evidence of trauma, obesity, cervical collar, macroglossia, and other factors in order to determine the type of airway approach best suited for each patient. The next important step is positioning via the head tilt-chin lift maneuver, which involves extending the patient’s neck by putting one hand on the forehead and the other hand on the neck to allow for the extension of the head in relation to the neck. This maneuver puts the patient into sniffing position, with the nose pointed upward and forward. The next maneuvar that can be performed is a chin lift by placing both hands underneath the mandible and the chin and lifting the mandible until the teeth barely touch. Another airway positioning method is called the jaw-thrust maneuver, which is safer in any patient with a potential cervical spinal cord injury. This method involves maintaining the spine in a neutral position and grabbing the sides of the angle of the mandible and lifting it forward to lift the jaw and open the airway. There are some differences between the pediatric and adult populations. For example, the large occiput of the pre-pubescent pediatric patient can lead to too much flexion of the neck and can cause tracheal obstruction. This is addressed by utilizing the head tilt-chin lift maneuver, but care must be taken to avoid overextension in the pediatric population as it can cause airway obstruction due to a weak trachea. However, the head tilt-chin lift may not be adequate to maintain a patent airway, and the jaw-thrust maneuver may need to be employed to prevent the pediatric, large, floppy tongue from obstructing the airway. Once properly positioned, the rescuer has the best shot at delivering effective breaths either via mouth to mouth or BVM. If there is continued difficulty at delivering breaths, then airway adjuncts like an oral pharyngeal airway (OPA) device or nasopharyngeal airway (NPA) can be useful for maintaining a patent airway to allow delivery of breaths in an unresponsive patient. NPA devices can be useful at maintaining the airway in an awake patient as well, which is beneficial if intubation is not the goal, the intubation needs to be delayed, or an awake intubation is necessary. NPA devices are plastic hollow or soft rubber tubes that a healthcare provider can utilize to help with oxygenation and ventilation of a patient that is difficult to oxygenate or ventilate via BVM. NPAs are passed through the nose and pass through to the posterior pharynx. NPAs do not cause patients to gag and therefore are the best airway adjunct route in an awake patient and the better choice in a semiconscious patient that may not tolerate an OPA due to the gag reflex. NPAs are also helpful when a patient's mouth is difficult to open, for example, if there is angioedema, trismus, or other factors. While NPAs are airway adjuncts for patients that are difficult to ventilate and oxygenate, they only act as a bridge to either a stabilized patient that is breathing without aid or a patient that requires a secure airway via endotracheal or nasotracheal (NT) intubation. The NT route for intubation was the preferred route among critical care and emergency physicians up until several decades ago. However, today, the majority of clinicians prefer the endotracheal route for intubation as it has shown to have better results and fewer complications. Some of the complications of NT intubation include sinusitis, nasal structure destruction due to localized pressure and decreased perfusion of nasal cartilage, and local abscesses. Furthermore, NT intubation requires narrow tubes making pulmonary toilet very difficult due to the increased airway resistance. However, there are clear advantages to NT intubation. NT intubation can be performed in the sitting position, which is valuable, especially in the pre-hospital setting when needing to intubate a patient in acutely decompensated heart failure that cannot lay flat. Other advantages include the patient’s inability to bite or manipulate the tube, better patient tolerance, decrease salivation, and better access to patient oral care. In addition, the NT tube is much more stable as it has the entire nasal tract holding it in place versus the endotracheal tube that flops out the mouth and can easily dislodge or become inserted into the right mainstem bronchus in the lungs. NT intubation can be performed blind or with a flexible bronchoscope. Blind NT intubation is difficult and requires expertise and skill. However, when indicated, can be a very useful skill both in the prehospital and hospital setting. Blind NT intubation decreases the need for neck movement and mouth opening, but can only be done in the awake and ventilating patient. NT intubation via a flexible bronchoscope also requires lots of expertise and skill, and it is useless if there is blood, vomitus, or fluid that will obscure the bronchoscope camera.[4]

A 17-year-old male with no previous medical history was admitted 2 days before his death to a local hospital after mild dyspnea. Electrocardiography, chest radiography, and blood analysis revealed no abnormalities. Blood oxygen saturation was 99%, and SARS-CoV-2 nasopharyngeal swabs tested negative; thus, he was discharged without prescriptions. After 2 days, the subject died suddenly during a pool party. Forensic autopsy was performed analyzing all anatomical districts. Cardiac causes were fully excluded after deep macroscopic and microscopic evaluation; lung and brain analyses showed no macroscopic pathology. Finally, a large subglottic solid mass was detected. The whitish neoplasm showed an aggressive invasion pattern to the thyroid and adjacent deep soft tissues and occluded the trachea. High-power microscopy showed sheets of small, uniform cells with scant cytoplasm; round nuclei; and small, punctate nucleoli, with immunohistochemical expression of CK8-18, AE1/AE3, and CD99. Using FISH analysis, the break-apart molecular probes (EWSR1 (22q12) Break - XL, Leica Biosystem, Nussloch, Germany) showed distinct broken red and green fluorochromes, diagnostic of Ewing sarcoma. The neoplasm was characterized as adamantinoma-like Ewing sarcoma, and the mechanism of death was identified as airway obstruction. The rarity of the case resides in the circumstances of death, which pointed to the possibility of sudden unexpected death due to heart disease, but an oncological cause and the underlying mechanism were finally diagnosed. The best method to perform autopsies is still complete, extensive, and systematic macroscopic sampling of organs and districts followed by histopathological analysis, in addition to immunohistochemical and molecular investigations in those cases in which they are necessary. In fact, when neoplasms are detected, the application of advanced techniques such as immunohistochemistry and molecular diagnostics is fundamental to accurately certify death.

Choking or foreign body airway obstruction occurs when a foreign body such as food, coins, or toys partially or completely obstruct the passage of air from the upper airway into the trachea. Choking affects either in the very young or the elderly[1]. In the young, the foreign body is likely to be food or a toy, while in the elderly it is almost always food. There is a bimodal distribution in the ages of patients, affecting primarily the young between the ages of 1 to 3 years and the elderly who are greater than 60 years. In 2015, 5,051 people died from choking. Of those, 2,848 (56%) were older than 74. Choking is the fourth leading cause of unintentional death,  the leading cause of infantile death, and the fourth leading cause of death among preschool children[2]. The most common objects on which children choke are food, coins, balloons, and other toys. In a Center for Disease Control review of nonfatal choking episodes in children that were treated in the emergency department, 13% of choking episodes were associated with coins and 19% were caused by candy or gum. Latex balloons are the most likely fatal aspirated foreign body, accounting for 29% of deaths by foreign body aspiration between 1972 and 1992. In the same time period, hot dogs were the most fatal food aspiration, accounting for 17% of food-related aspiration fatalities[3]  Of the adult fatalities associated with choking, there is a strong association with dementia (including Alzheimer disease) and Parkinson disease[4]. Decreased salivation in the elderly is also implicated as this impairs the ability to transfer food during swallowing.

Bacterial tracheitis was first described in medical literature in the 1920s, despite the name not being coined until much later. The disease was initially referred to as acute laryngotracheobronchitis. Bacterial tracheitis, also known as bacterial croup, acute laryngotracheobronchitis, or membranous croup, is a potentially lethal infection of the subglottic trachea. It is often a secondary bacterial infection preceded by a viral infection affecting children, most commonly under age six. Concern for airway protection is the mainstay of treatment as thick, mucopurulent secretions can cause airway narrowing. Treatment is aimed at the protection of the airway, assessing the need for endoscopy for therapeutic and/or diagnostic reasons, and antimicrobial therapy. On presentation, this must be distinguished from the more immediately lethal epiglottitis.[1][2][3]