Three-dimensional printing of external airway splints for tracheomalacia

Tissue-engineered tracheal implants: Advancements, challenges, and clinical considerations

Restoration of extensive tracheal damage remains a significant challenge in respiratory medicine, particularly in instances stemming from conditions like infection, congenital anomalies, or stenosis. The trachea, an essential element of the lower respiratory tract, constitutes a fibrocartilaginous tube spanning approximately 10-12 cm in length. It is characterized by 18 ± 2 tracheal cartilages distributed anterolaterally with the dynamic trachealis muscle located posteriorly. While tracheotomy is a common approach for patients with short-length defects, situations requiring replacement arise when the extent of lesion exceeds 1/2 of the length in adults (or 1/3 in children). Tissue engineering (TE) holds promise in developing biocompatible airway grafts for addressing challenges in tracheal regeneration. Despite the potential, the extensive clinical application of tissue-engineered tracheal substitutes encounters obstacles, including insufficient revascularization, inadequate re-epithelialization, suboptimal mechanical properties, and insufficient durability. These limitations have led to limited success in implementing tissue-engineered tracheal implants in clinical settings. This review provides a comprehensive exploration of historical attempts and lessons learned in the field of tracheal TE, contextualizing the clinical prerequisites and vital criteria for effective tracheal grafts. The manufacturing approaches employed in TE, along with the clinical application of both tissue-engineered and non-tissue-engineered approaches for tracheal reconstruction, are discussed in detail. By offering a holistic view on TE substitutes and their implications for the clinical management of long-segment tracheal lesions, this review aims to contribute to the understanding and advancement of strategies in this critical area of respiratory medicine.

Personalized 3D-Printed Bioresorbable Airway External Splint for Tracheomalacia Combined With Congenital Heart Disease

Severe tracheomalacia (TM) patients with respiratory symptoms need surgical intervention, including aortopexy, internal stents or external splint. While some patients continue to have respiratory symptoms after tracheal relief, and there is no evidence to support any one surgery therapy over another. Here we introduce a clinical safety and efficacy of the three-dimensional (3D)-printed bioresorbable airway external splints in treating congenital heart disease (CHD) patients with severe TM. From May 2019 to September 2020, nine patients with severe TM were enrolled. The median age was 5 months (range, 3–25 months), and the median weight was 7.5 kg (range, 3–15 kg). All patients had wheezing, and two patients were assisted by machine ventilation (MV) preoperatively. The median length of TM was 1.5 cm (range, 1.0–3.0 cm). All patients underwent suspension of a “C”-shaped lumen airway external splint, which were designed in SOLIDWORKS and made of polycaprolactone (PCL). The airway external splint could provided effective support for at least 6 months and was completely degraded into carbon dioxide and water within 2–3 years. The median time of postoperative machine assisted ventilation was 23.7 h (range, 3.3–223.4 h), and the median time of ICU stay was 9 days (range, 4–25 days). The median follow-up time was 18 months (range, 12–24 months). Respiratory symptoms were all relieved, and no external splint-associated complications occurred. The 3D computed tomography reconstruction showed no airway stenosis. Personalized 3D-printed bioresorbable airway external splint can not only limit external compression and prevent airway collapse but also ensure the growth potential of the airway, which is a safe, reliable and effective treatment for CHD with TM.

Development and clinical translation of tubular constructs for tracheal tissue engineering: a review

Effective restoration of extensive tracheal damage arising from cancer, stenosis, infection or congenital abnormalities remains an unmet clinical need in respiratory medicine. The trachea is a 10-11 cm long fibrocartilaginous tube of the lower respiratory tract, with 16-20 tracheal cartilages anterolaterally and a dynamic trachealis muscle posteriorly. Tracheal resection is commonly offered to patients suffering from short-length tracheal defects, but replacement is required when the trauma exceeds 50% of total length of the trachea in adults and 30% in children. Recently, tissue engineering (TE) has shown promise to fabricate biocompatible tissue-engineered tracheal implants for tracheal replacement and regeneration. However, its widespread use is hampered by inadequate re-epithelialisation, poor mechanical properties, insufficient revascularisation and unsatisfactory durability, leading to little success in the clinical use of tissue-engineered tracheal implants to date. Here, we describe in detail the historical attempts and the lessons learned for tracheal TE approaches by contextualising the clinical needs and essential requirements for a functional tracheal graft. TE manufacturing approaches explored to date and the clinical translation of both TE and non-TE strategies for tracheal regeneration are summarised to fully understand the big picture of tracheal TE and its impact on clinical treatment of extensive tracheal defects.

Current concepts in tracheobronchomalacia: diagnosis and treatment

Airway collapse from dynamic tracheobronchomalacia (TBM), static compression from vascular compression, and/or tracheobronchial deformation are challenging conditions. Patients are best assessed and managed by a multidisciplinary team in centers specializing in complex pediatric airway disorders. Suspicion is made through clinical history and physical examination, diagnosis of location and severity by dynamic 3-phase bronchoscopy, and surgical treatment planning by MDCT and other studies as necessary to completely understand the problems. The treatment plan should be patient-based with a thorough approach to the underlying pathology, clinical concerns, and combined abnormalities. Patients should undergo maximum medical therapy prior to committing to other interventions. For those children considered candidates for surgical intervention, all other associated conditions, including vascular anomalies, chest wall deformities, mediastinal lesions, or other airway pathologies, should also be considered. Our preference is to correct the airway lesions at the same operation as other comorbidities, if possible, to prevent multiple reoperations with their attendant increased risks. We also strongly advocate for the use of recurrent laryngeal nerve monitoring in all cases of cervical or thoracic surgery to minimize the risks to vocal cord function and laryngeal sensation. Studies that evaluate the effect of these interventions on the patient and caregiver's quality of life are needed to fully grasp the impact of TBM on this challenging patient population.

Tracheobronchomalacia, Tracheobronchial Compression, and Tracheobronchial Malformations: Diagnostic and Treatment Strategies

Tracheobronchomalacia (TBM) is an excessive dynamic narrowing of the airway that is greatest with increased mediastinal pressure such as coughing, Valsalva, and forced expiration. Airway compression and/or cartilage malformation is a fixed or static narrowing of the airway typically caused by great vessel malposition and/or abnormalities and may also contribute to airway narrowing. Although imprecise and misleading, the term TBM is often used to represent both problems, static and dynamic airway narrowing, which only serves to confuse and may mislead the treatment team into ineffective therapies. The consequences of airway narrowing caused by dynamic TBM and/or static compression includes a range of clinical signs and symptoms, depending on the location, extent, and severity of the airway collapse. All patients with mild to severe TBM benefit from medical management to optimize airway clearance of mucus. The milder cases of TBM may become asymptomatic with this therapy, allowing time for the child to grow and the airway to enlarge without the consequences of recurrent infections. In cases of more severe TBM with clinical sequelae, more aggressive management may be warranted. Multiple options for surgical intervention are available. This article discusses the details of clinical presentation, evaluation, diagnosis, and a variety of treatments.

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

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

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

3D Printing for the Clinic: Examining Contemporary Polymeric Biomaterials and Their Clinical Utility

The advent of additive manufacturing offered the potential to revolutionize clinical medicine, particularly with patient-specific implants across a range of tissue types. However, to date, there are very few examples of polymers being used for additive processes in clinical settings. The state of the art with regards to 3D printable polymeric materials being exploited to produce novel clinically relevant implants is discussed here. We focus on the recent advances in the development of implantable, polymeric medical devices and tissue scaffolds without diverging extensively into bioprinting. By introducing the major 3D printing techniques along with current advancements in biomaterials, we hope to provide insight into how these fields may continue to advance while simultaneously reviewing the ongoing work in the field.

Tracheomalacia and Tracheobronchomalacia in Pediatrics: An Overview of Evaluation, Medical Management, and Surgical Treatment

Tracheobronchomalacia (TBM) refers to airway collapse due to typically excessive posterior membrane intrusion and often associated with anterior cartilage compression. TBM occurs either in isolation or in association with other congenital or acquired conditions. Patients with TM typically present non-specific respiratory symptoms, ranging from noisy breathing with a typical barking cough to respiratory distress episodes to acute life-threatening events and recurrent and/or prolonged respiratory infections. There are no definitive standardized guidelines for the evaluation, diagnosis, and treatment of TBM; therefore, patients may be initially misdiagnosed and incorrectly treated. Although milder cases of TBM may become asymptomatic as the diameter of the airway enlarges with the child, in cases of severe TBM, more aggressive management is warranted. This article is an overview of the clinical presentation, evaluation, diagnosis, medical management, and surgical treatment options in pediatric tracheomalacia.