"Tracheal thinness" - congenital tracheal stenosis

This is the 4826th article of Da Yi Xiao Hu

Congenital tracheal stenosis (CTS) is a very rare congenital obstructive tracheal disease with an incidence of only 1/64,500 live births. It often presents with repeated lung infections and dyspnea, or even respiratory failure, and is easily misdiagnosed or missed clinically. Except for some mild cases of stenosis, children with congenital tracheal stenosis are usually in danger of death. If they are not diagnosed and treated in time, the mortality rate is as high as 50% to 80%. Here, we will take you to learn about the "thin trachea" - congenital tracheal stenosis.

1. What is congenital tracheal stenosis?

Congenital tracheal stenosis refers to the narrowing of the tracheal lumen due to the complete absence of tracheal rings and tracheal mucosa during embryonic development. The normal trachea is composed of a hyaline cartilage ring and inter-annular ligaments that extend backward from the "C"-shaped notch. The notch on the posterior wall of the "C"-shaped cartilage ring is closed by a membrane wall, which is composed of tracheal muscles composed of elastic fibers and smooth muscles. Simply put, congenital tracheal stenosis is caused by abnormalities in the anatomical structure: the complete tracheal cartilage ring, that is, the appearance of the "O"-shaped ring in the narrow part replaces the normal "C"-shaped tracheal cartilage ring, and the disappearance of the membranous structure of the posterior wall of the trachea significantly reduces the compliance of the trachea in the narrowed section. At the same time, the glands and connective tissue in the submucosal layer of the trachea proliferate, causing further narrowing of the lumen. Congenital tracheal stenosis rarely exists alone, accounting for only 10% to 25%. It is often accompanied by other congenital malformations, the most common of which is cardiovascular malformation. Foreign reports show that its incidence rate is as high as 50%. Cardiovascular malformations include complete vascular rings, incomplete vascular rings and congenital heart malformations. These malformations may aggravate or mask related clinical manifestations and delay the diagnosis of congenital tracheal stenosis.

Congenital tracheal stenosis has different types. According to the length of tracheal stenosis, it can be divided into short segment stenosis (stenosis segment <30% of the total tracheal length or <6 tracheal rings) and long and short stenosis (stenosis segment ≥30% of the total tracheal length or ≥6 tracheal rings). According to the anatomical structure of the trachea, it mainly includes diffuse stenosis (the entire trachea is widely underdeveloped), funnel-shaped stenosis (the trachea is thick at the upper end, gradually becomes thinner downward until it reaches the carina or above the carina, like a funnel) and localized stenosis (a small segment of the trachea is narrowed, with a maximum of 3 tracheal cartilage rings). According to the abnormal bronchial morphology, it can be divided into type I, normal bronchial bifurcation type; type II, including right upper bronchial bifurcation; type III, trifurcated branch type at the carina; type IV, unilateral bronchial tree type, i.e. single lung type.

This figure is taken from the literature "Congenital Tracheal Stenosis"

2. How to detect congenital tracheal stenosis early?

The clinical symptoms of children with congenital tracheal stenosis vary, usually depending on the length, location and severity of the stenosis of the lumen, as well as whether there are other malformations. Generally, the more severe the stenosis, the earlier the symptoms appear. In the process of caring for their children, some parents will find that their children have repeated wheezing, shortness of breath, infection, dyspnea, three-recess sign, and even respiratory failure after birth. They will first take their children to the respiratory medicine or otolaryngology clinic for treatment. The doctor is likely to diagnose them as "bronchitis", "upper respiratory tract infection", "asthma", "laryngomalacia or laryngeal cartilage dysplasia", etc. In fact, the real cause of these symptoms may not be some diseases that people often think of, but congenital tracheal stenosis, which is easy to cause delayed diagnosis clinically and seriously affect the quality of life of children. Clinically, children with severe tracheal stenosis will experience respiratory distress a few days after birth, which may be accompanied by wheezing, cyanosis and barking-like hoarseness, and most of them need life support. The clinical symptoms of mild stenosis are not typical and are more common in older children. There may be no obvious symptoms in a calm state, but wheezing and hoarseness may occur when crying or after exercise, and activity tolerance decreases. In addition, as the child grows older, the amount of activity increases, and the demand for oxygen supply increases, the clinical symptoms will gradually worsen. Therefore, it is necessary to be alert to these symptoms. For children suspected of congenital tracheal stenosis, an outpatient CT scan (three-dimensional reconstruction) can be performed. This is currently the preferred method for excluding congenital tracheal stenosis. At the same time, bronchoscopy can determine the location, type, degree and length of tracheal stenosis, and is considered the gold standard for the diagnosis of congenital tracheal stenosis.

3. What should I do if I have congenital tracheal stenosis?

Individualized treatment: Children with mild stenosis and no clinical symptoms should be followed up with regular medical visits. There is no clear treatment plan yet, so individualized treatment is required. Children should strengthen their physical fitness, take active preventive measures and receive symptomatic treatment, including lung physiotherapy, humidified oxygen inhalation, anti-infection treatment and vitamin D supplementation.

Surgical treatment: Since drugs and conservative treatment have little effect on children with symptomatic congenital tracheal stenosis and are relatively limited, surgical treatment is currently the most commonly used method. Years of clinical experience have shown that surgical correction of congenital tracheal stenosis has a safe and reliable effect and can significantly improve the quality of life. Surgical techniques include: sliding tracheoplasty, segmental resection, patch plasty, wedge resection, tracheal autotransplantation and tissue-engineered trachea. Among them, Slide tracheoplasty is currently the mainstream technology for the treatment of congenital tracheal stenosis and is the preferred method for long-segment and diffuse tracheal stenosis. Preoperative multidisciplinary consultation is also required, including reception, imaging, bronchoscopy, anesthesiology, nutrition, intensive care, bedside care and surgical team, etc., to jointly determine the treatment and postoperative care plan for the child. Postoperatively, attention should be paid to position care and airway management, and invasive and non-invasive ventilation care should be strengthened.

4. Why should congenital tracheal stenosis be followed up?

With the continuous development and maturity of imaging and surgical techniques, the evaluation of the efficacy of congenital tracheal stenosis is no longer limited to the success rate of surgery, but the long-term quality of life of the child. Congenital tracheal stenosis is not an obstacle to the healthy and fulfilling life of the child. For children with congenital tracheal stenosis, no matter what treatment plan is chosen, regular follow-up should be carried out according to the doctor's advice, so as to pay attention to the overall quality of life of the child, including respiratory function, swallowing function, language function, psychological and social function, and the growth of the reconstructed trachea, so as to improve clinical decision-making, formulate personalized rehabilitation plans for the child, better return to family and school, and maximize the benefits of the child. The examinations involved may include: chest X-ray, electrocardiogram, pulmonary function, laryngeal ultrasound, echocardiography, CT reconstruction, bronchoscopy and cardiopulmonary exercise test (CPET), etc. The specific follow-up content needs to be comprehensively judged and selected according to the actual situation of the child and combined with the experience of each unit.

Author: Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine

Shi Songsong Cai Juan Shen Biyu