Tracheal and bronchial developmental disorders

　　The common causes of tracheal and bronchial developmental disorders are that due to some factors during the embryonic period, the trachea and bronchi do not develop, or there is a disorder when the foregut develops into the trachea and esophagus, with abnormal origin of the bronchi above the lobe, which can form different types and degrees of malformations.

　　Tracheal and bronchial developmental disorders often accompany other malformations, such as tracheoesophageal fistula and abnormalities in the heart, urinary, and reproductive systems. Tracheal and bronchial developmental disorders are severe congenital diseases and should be checked during pregnancy to avoid the birth of affected children.

　　The clinical manifestations of tracheal and bronchial developmental disorders vary with different causes, and common malformations include:

　　1. Tracheal and bronchial atresia

　　This kind of malformation is very rare and often accompanied by other malformations, such as tracheoesophageal fistula and abnormalities in the heart, urinary and reproductive systems. Floyd et al. classified such malformations into 3 subtypes: Type I, accounting for 10%, including partial tracheal atresia, with the distal trachea being a short segment of normal trachea connected to the anterior wall of the esophagus; Type II, accounting for 59%, with complete absence of the trachea, but normal bronchi and carina, with the carina connected to the esophagus; Type III, accounting for 31%, with complete absence of the trachea, and the bronchi originating from the esophagus. There are reports that classify the malformations based on the degree of development of the affected trachea and bronchi, and the presence or absence of tracheoesophageal fistula, into 7 types. The common types listed are, with the most common type being the complete absence of the trachea between the larynx and the esophagus, accounting for about 50%, while other types account for only 5% to 10%.

　　2. Bronchial stenosis

　　True congenital bronchial stenosis is rare. The most common type of bronchial stenosis is secondary right main bronchial stenosis, caused by incorrect or frequent suctioning during long-term mechanical ventilation in infants and young children, leading to inflammatory changes and granulation tissue accumulation at the opening of the main bronchus. Clinical manifestations include dyspnea, and if combined with tracheal stenosis, there may be speech disorders, and stridor can be seen on physical examination.

　　3. Tracheal diverticula

　　Congenital tracheobronchial diverticula are relatively common, with tracheal diverticula being the most common, possibly originating from the diagnosis and treatment of tracheal diverticula.

　　Tracheal diverticula are often located on the right wall of the trachea 1-3 cm above the carina, usually solitary, asymptomatic, can retain foreign bodies, often found unexpectedly during surgery, bronchoscopic examination, or post-mortem examination. Bronchoscopy can confirm the diagnosis, no special treatment is required. Symptoms may be due to stenosis of the accessory bronchus or other pulmonary malformations, leading to recurrent pneumonia, wheezing, or neonatal respiratory distress.

　　4. Abnormal origin of bronchi

　　Abnormal origin of bronchi refers to the abnormal origin of large bronchi above the lobe, which is extremely rare, while the abnormal origin of segmental or segmental bronchi is more common, considered to be an anatomical variation, should be noted during bronchoscopy and surgery, and has no other clinical significance.

　　Abnormal origin and branching of bronchi are often asymptomatic and have no significant clinical significance, but occasionally secondary recurrent lung infections and other symptoms may occur. Esophageal contrast imaging can show that part of the lung tissue communicates with the esophagus through a bronchial-like structure, the abnormal origin of the lobar or segmental bronchus originating from the esophagus can be on the right or left lung, or the upper or lower lobe, and the blood supply to the involved lobe has various conditions, some lobes have normal pulmonary blood supply, while others are supplied by the systemic circulation. Extrapulmonary and intrapulmonary types of pulmonary sequestration (defined as abnormal blood supply and no bronchial communication) occasionally communicate with the esophagus or other foregut-derived organs, causing confusion in nomenclature, so some people refer to all such malformations as congenital bronchopulmonary foregut anomalies.

　　5. Tracheobronchial esophageal fistula

　　This kind of malformation accounts for 1/800 to 1/5000 of newborn infants. Simple tracheoesophageal fistula is rare, accounting for about 4% of tracheoesophageal malformations, while tracheoesophageal fistula with esophageal atresia is more common, accounting for about 88% of tracheoesophageal malformations. It can be divided into five main types: short atresia of the esophagus, the distal esophagus originating from the lower segment of the trachea, which is the most common type, accounting for more than 80%; esophageal atresia without tracheoesophageal fistula, in which the trachea usually develops normally; the presence of esophageal tracheal fistula without esophageal atresia; esophageal atresia with fistula on the side of the atresia; esophageal atresia with fistula between the trachea and the side of the atresia and the anal side.

　　Bronchial esophageal fistula formed between the esophagus and the right main bronchus is rare. It is also divided into two clinical pathological types: with or without esophageal atresia. The former has a blind end of the esophagus, which is the most common type.

　　Low birth weight is a high-risk factor for this disease, with 70% seen in low-weight infants at birth, mostly due to other diseases and premature birth. Males are slightly more than females, and excessive saliva, vomiting white foam, and coughing, vomiting, and dyspnea during feeding may occur after birth. These symptoms are significantly reduced after stopping feeding. If not treated in time, infants and young children may develop aspiration pneumonia due to oral secretions, food, or gastric contents reflux, leading to fever, shortness of breath, dehydration, and in severe cases, death due to pulmonary complications. Full-term infants with a simple fistula can survive 100%.

　　Tracheal and bronchial developmental disorders are a type of congenital disease. Prevention mainly focuses on prenatal examination, striving to achieve early detection and early treatment. Good pre-pregnancy consultation and pre-pregnancy examination should be done to avoid the occurrence of congenital diseases.

　　What examinations should be done for tracheal and bronchial developmental disorders? Briefly described as follows:

　　1. X-ray examination.X-ray chest films of children with tracheal and bronchial atresia show a triangular lesion area close to the hilum, with the tip pointing towards the hilum, showing high radiopacity and linear, branching mucoid cystic manifestations. The normal lung parenchyma and mediastinum around it will be compressed and displaced, indicating bronchial origin abnormality. X-ray manifestations of children with tracheoesophageal fistula show chronic infection or emphysema signs of lung tissue, and fluoroscopy can also show reduced gastric bubble or intestinal gas.

　　2. CT examination.It can display the characteristic of central cystic mucoid cyst in bronchial atresia, thereby distinguishing bronchial源性 cysts or lobar emphysema. Three-dimensional reconstruction CT examination is the best means to diagnose the degree and scope of bronchial stenosis. For tracheal diverticula, CT can diagnose accessory bronchus, and coronal CT does not need to use bronchial angiography to better diagnose accessory bronchus.

　　3. Bronchoscopy examination.Tracheal diverticula can be seen directly, and the number and size of diverticula can be understood; tracheoesophageal fistula can be seen through the fistula opening, and different types of abnormal large bronchus origins can be seen through bronchoscopy.

　　4. Angiography examination.According to statistics, bronchial abnormalities may originate from bronchial angiography, with 7/1500 cases showing the left apical segment originating from the left main bronchus, among which 4/7 have tracheal obstruction. Tracheal diverticula can be seen directly during bronchial angiography, and the accessory bronchus can be evaluated. The bronchial tracheal瘘造影 method is to first place a gastric tube, often encountering resistance at about 10-12 cm, then inject iodine oil, perform angiography, and diagnose accordingly.

　　The dietary principles for patients with tracheal and bronchial developmental disorders are briefly described as follows:

　　1. Suitable for eating

　　Eat more food that can relieve cough, asthma, phlegm, warm the lungs, and strengthen the spleen, such as whitebait, loquat, pomelo, winter melon, yam, chestnut, lily, kelp, and seaweed, etc. Pay attention to drink plenty of water and have a diverse diet, and eat more high-protein, high-vitamin, low-animal-fat, and easily digestible foods, as well as fresh fruits and vegetables.

　　2. Avoid eating

　　Do not eat stale, deteriorated, or刺激性 things, eat less smoked, roasted, pickled, fried, and salty foods, mix coarse and fine grains for staple foods to ensure nutritional balance.

　　For any type of tracheobronchial developmental disorder, surgical treatment is the only effective means.

　　1. Tracheobronchial atresia.It is recommended to perform tracheal or bronchialoplasty surgery to treat the prevention of lung abscess. The current tracheal atresia reconstruction technique first closes the distal esophagus and creates a gastric fistula, inserts a tracheal tube into the esophagus to place it above the level of the tracheoesophageal fistula, provides mechanical ventilation and enteral feeding for 9 months, creates a tracheal fistula in the upper segment, severs the tracheoesophageal connection, and later uses an interposed colon to reconstruct the digestive tract.

　　2. Tracheobronchial stenosis.Jaffe (1997) reported that balloon dilation therapy was used to treat 6 cases of congenital or secondary tracheal and bronchial stenosis, of which 4 were successful. Repeated bronchial dilation may be necessary to protect normal lung tissue function and treat infection. If the infection after bronchial dilation cannot be cured, bronchoplasty can reduce the rate of lung resection. Some people also use laser therapy for granulomatous tracheobronchial stenosis.

　　3. Tracheal diverticulum.McLaughlin et al. (1985) reported 18 cases of accessory bronchus in children, manifested as recurrent pneumonia and other respiratory symptoms. Five bronchography cases showed that bronchial stenosis and involved lung segment bronchial dilation, symptoms were alleviated after surgical resection.

　　4. Abnormal bronchial origin.Abnormal communication between the bronchus and esophagus can cause persistent or recurrent pneumonia in the infantile period. Surgical resection of chronically infected lung tissue can alleviate the above symptoms.

　　5. Tracheoesophageal fistula.Treatment principles: Avoid swallowing or regurgitation into the respiratory tract; prevent and treat pulmonary complications; maintain nutrition and water-salt balance. The purpose of surgical treatment is to close the fistula, resect the fistula, and establish esophageal continuity. It can be completed in one stage, or it can be completed in two stages if the local conditions are not ideal, infection is severe, or the overall condition is poor.