Tracheomalacia is a pathological softening of the cartilaginous framework of the trachea, leading to expiratory stenosis of the respiratory tract. It is manifested by signs of respiratory obstruction: shortness of breath, cough, dysphonia, stridor on exhalation, attacks of suffocation. Recurrent infections of the lower respiratory tract are characteristic. In the diagnosis of pathology, tracheobronchoscopy, FVD examination, multispiral CT, MRI are used. The palliative approach provides for the rehabilitation of TBT, antimicrobial therapy, tracheostomy; radical tactics involve performing endoprosthetics, circular resection of a pathologically altered trachea, tracheopexy.
ICD 10
Q32.0 J95.8
Meaning
Tracheomalacia is a partial or complete violation of the skeletal function of the trachea due to the weakness of its cartilaginous base. Congenital pathology is diagnosed in 1:2100-1:2200 children. The frequency of acquired form in patients of pulmonological departments, according to endoscopy, ranges from 5%-23%. Tracheomalacia is more often diagnosed in men (82% versus 18% in women), which is probably due to the greater prevalence of COPD and chronic bronchitis in the male population. The frequency of tracheomalacia increases with age.
Causes of tracheomalacia
Primary pathology refers to congenital defects of the tracheobronchial tree (TBT). The reliable causes of the anomaly are unknown, but there are indications of its hereditary nature. Primary tracheomalacia occurs within the framework of such genetic syndromes as cystic fibrosis, Ehlers-Danlos syndrome. The role of prenatal exposure to teratogenic factors is not excluded, as evidenced by the combination of tracheomalacia with other congenital anomalies ‒ laryngomalacia, bronchomalacia, tracheobronchomegaly, tracheobronchial fistulas, esophageal atresia, CHD.
Secondary tracheomalacia is more common than congenital and is associated with various pathological changes in TBT. The most significant etiofactors are injuries and chronic inflammation of the trachea:
- prolonged or multiple tracheostomy, intubation, ventilator, tracheal stenting;
- surgical interventions, iatrogenic injuries, wounds in the neck;
- compression of the trachea from the outside by abnormally located vessels, chest goiter, cyst, neoplasm, abscess;
- chronic obstructive pulmonary disease;
- chronic tracheobronchitis;
- recurrent perichondritis of the trachea.
Non-specific factors contributing to the progression of tracheomalacia are obesity, hyperglycemia, GERD, shock states, radiation therapy, high-dose glucocorticosteroid therapy.
Pathogenesis
The supporting frame of the trachea is represented by C-shaped cartilaginous semicircles, the number of which can range from 16 to 22. They cover the anterior surface of the trachea by more than two-thirds of the semicircle. The posterior (membranous) surface is represented by muscle tissue, it is malleable and provides mobility of the trachea when breathing and coughing. From the inside, the breathing tube is lined with mucous tissue, from the outside it is covered with an adventitial layer.
The normal ratio of cartilaginous and soft tissue structures in the trachea is 4.5:1, however, with tracheomalacia, this ratio decreases to 2:1. Various pathological processes contribute to the loss of cartilage elasticity: congenital connective tissue dysplasia; chronic traumatization leading to cicatricial stenosis; compression that disrupts blood supply; chronic inflammation causing purulent meltdown.
Dystrophic and destructive changes occur in the tracheal wall: atrophy of cartilaginous elastic fibers, hemorrhages, sequestration, perichondrial fibrosis. The proliferation of chondrocytes is disrupted, normal hyaline cartilage is replaced by coarse-fibrous connective tissue. As a rule, chondrolysis captures at least 2-3 cartilaginous half-rings.
The weakening and softening of cartilage tissue causes the collapse of the anterior and lateral tricheal walls with a complete or partial collapse of the organ lumen. This process is especially pronounced during the exhalation phase and with coughing paroxysms.
Classification
Depending on the producing factors, tracheomalacia is divided into primary (congenital) and secondary (acquired). Segmental (local) and widespread (diffuse) forms are differentiated by length. With concomitant softening of the cartilage of the main bronchi, tracheobronchomalacia is diagnosed, with laryngotracheobronchomalacia being involved in the larynx process.
According to the type of collapse of the walls of the trachea during exhalation , the following forms of pathology are distinguished:
- semilunar – tracheal lumen is reduced in the anterior-posterior direction;
- slit-shaped (sabre-shaped) – the lumen of the trachea is narrowed bilaterally;
- concentric – the trachea is narrowed as a result of prolapse of all its walls.
Based on the bronchological picture , three degrees of severity of tracheomalacia are distinguished during the exhalation phase:
- light – the diameter of the trachea is reduced by more than 1/3;
- average – the trachea subsides by more than 1/2;
- heavy – the trachea is narrowed by 4/5, or its walls are in contact with each other.
Tracheomalacia symptoms
The severity of clinical manifestations correlates with the degree of tracheal collapse. Approximately 10% of patients with tracheomalacia have no symptoms, and pathology is detected by endoscopic examination of TBT. With a mild degree, constant cough, slight shortness of breath worries. Functionally significant collapse is accompanied by airway obstruction.
The most constant sign of tracheomalacia is shortness of breath with physical effort. It usually occurs when the TBT is narrowed by 50% or more of the original diameter. When the tracheal lumen is occluded by 75%, expiratory stridor occurs – a difficult, noisy exhalation with a whistle. An indicator of respiratory failure is cyanosis of the skin.
There may be a cough (dry barking or with sputum), hemoptysis, chest pain. If the larynx is involved in the pathological process, it is possible to change the voice – dysphonia. In children with congenital tracheomalacia, the severity of symptoms is aggravated by feeding, screaming, ARVI.
Complications
Pronounced obstruction of the airways causes an attack of suffocation, in which the risk of death from asphyxia increases. Violation of the natural mechanisms of TBT purification contributes to the development of recurrent respiratory infections: bacterial bronchitis, prolonged pneumonia. Children with tracheomalacia and other congenital malformations lag behind their peers in physical development, get tired quickly. Due to the developing chronic respiratory insufficiency, pulmonary hypertension, pulmonary heart develops.
Diagnostics of tracheomalacia
Tracheobronchomalacia should be suspected in children with connective tissue dysplasia, patients with cicatricial tracheal stenosis, recurrent inflammatory diseases of TBT, complaining of shortness of breath, noisy breathing, constant cough. After a clinical examination by a pulmonologist, an extended examination is prescribed, including the following methods:
- Tracheobronchoscopy. Endoscopic examination is the main method of detecting intraluminal changes in TBT. A typical visual pattern for tracheomalacia is a decrease in the diameter of the trachea during the exhalation phase in the form of a “fish mouth”. The examination is supplemented by taking a biopsy, if necessary, by a therapeutic procedure (bougie, stenting).
- Methods of X-ray imaging. X-ray of the trachea with functional tests helps to identify the collapse of the organ on exhalation or when coughing. Multispiral CT of the tracheobronchial tree has the greatest specificity and sensitivity. 3D reconstruction (virtual bronchoscopy), a sample with forced exhalation helps to consider the smallest structural changes of the trachea. The value of MRI is the ability to assess the condition of the surrounding organs, the thickness of the tracheal wall.
- Spirometry. Tracheomalacia is characterized by a change in both volumetric and velocity characteristics of the airflow. There is a drop in the VEL, the Tiffno index, and the exhalation rate. There is a serration on the forced exhalation curve in the form of a “shark tooth”.
Differential diagnosis
Clinical manifestations of tracheomalacia are nonspecific, which causes difficulties in the correct interpretation of the diagnosis. As part of the diagnosis, it is necessary to exclude other diseases accompanied by difficulty breathing and coughing:
- bronchial asthma;
- bronchial obstruction against the background of ARVI (rhinovirus infection, RSV);
- congenital stridor;
- TBT foreign bodies;
- tracheobronchomegaly (Munier-Kuhn syndrome);
- functional tracheal stenosis.
Tracheomalacia treatment
Conservative treatment
Conservative or radical surgical tactics may be chosen in relation to the disease. The first is justified in the case of widespread tracheomalacia, involves thorough rehabilitation of TBT with a series of therapeutic bronchoscopes, inhalations, and antibacterial therapy. CPAP therapy is used to prevent the collapse of the VDP. With severe respiratory insufficiency, an emergency tracheostomy or endoscopic stenting of the trachea may be required.
Surgical treatment
In the case of segmental tracheomalacia, surgical treatment is indicated. If technically possible, circular resection of the altered trachea section is performed with simultaneous imposition of an intertracheal anastomosis. In some cases, a phased restoration of the integrity of the respiratory tract on a T-shaped tube is carried out. Autografts, ceramic rings, and biodegradable stents are used to form an optimal framework that supports the stability of the airway lumen.
There are reports of successful surgical removal of tracheomalacia using thoracoscopic posterior tracheopexy (fixation of the trachea to the spinal ligament), tracheoaortopexy (fixation of the anterior tracheal wall to the aorta), aortopexy (suturing of the aorta to the posterior surface of the sternum).
Prognosis and prevention
To date, the optimal methods of treating tracheomalacia are not standardized, they are in the stage of clinical testing. With non-radical surgery, restenosis and anastomosis failure may develop. Carefully considered therapeutic tactics allows you to avoid complications and permanently eliminate airway obstruction. Prevention of secondary tracheomalacia involves compliance with the optimal timing of tracheostomy, intubation, prevention of iatrogenic injuries, timely therapy of inflammatory processes of TBT.
Literature
- Treatment of tracheo(broncho)malacia in children. Janssen A, Mastouri M, Boboli H, Demarche M, Brandt H, Moonen V, Seghaye MC, Kempeneers C. Rev Med Liege. 2021 Mar;76(3):145-151. link
- Tracheal ring-graft reinforcement in lieu of tracheostomy for tracheomalacia. Cacciaguerra S, Bianchi A. Pediatr Surg Int. 1998 Oct;13(8):556-9. link
- Tracheomalacia. Messineo A, Filler RM. Semin Pediatr Surg. 1994 Nov;3(4):253-8. link
- Tracheomalacia with esophageal atresia and tracheoesophageal fistula in fetal rats. Qi BQ, Merei J, Farmer P, Hasthorpe S. 1997 Nov;32(11):1575-9. link
- Tracheal diverticula after tracheoesophageal fistula repair: case series and review of the literature. Shah AR, Lazar EL, Atlas AB. J Pediatr Surg. 2009 Nov;44(11):2107-11. link
