Background
Tracheomalacia is an abnormal collapse of the tracheal walls. It may occur in an isolated lesion or can be found in combination with other lesions that cause compression or damage of the airway. Tracheomalacia is usually benign, with symptoms due to airway obstruction. As such, this condition is often mistaken for chronic asthma or prolonged bronchiolitis.
This shows the trachea during inspiration and expiration. Tracheal collapse of more than 50% during expiration is diagnostic of tracheomalacia.
Pathophysiology
Tracheomalacia may occur as a primary lesion, in which case the cartilage of the trachea develops abnormally. This results in tracheal walls that are soft and collapse during respiration. The collapse causes airflow obstruction and wheezing, stridor, or both. If the lesion is extrathoracic, the collapse and airway sounds occur primarily during inspiration. If the lesion is intrathoracic, the collapse and airway sounds occur primarily during exhalation. Because most of the trachea is intrathoracic, exhalatory collapse accounts for most cases of tracheomalacia.
Tracheomalacia may also be found in conjunction with lesions that compress the airway, such as mediastinal masses, vascular slings, and vascular rings. It also occurs with increased frequency in children with chronic inflammation of the proximal airways. Less common in asthma, this etiology of tracheomalacia is more often seen in children with chronic lung disease of infancy, gastroesophageal reflux, or other forms of chronic aspiration.
Primary tracheomalacia is sometimes referred to as type 1, tracheomalacia associated with extrinsic compression is sometimes referred to as type 2, and tracheomalacia associated with intra-airway irritation/inflammation is sometimes referred to as type 3.
Tracheomalacia is frequently found after repair of a tracheoesophageal fistula and may cause significant symptoms for several years after the repair.
Epidemiology
Frequency
United States
The frequency of tracheomalacia is unclear. The condition appears to primarily derive from a developmental defect in the cartilage of the tracheal wall. Therefore, the lesion usually occurs in infants and young children. It is frequently found in children who have undergone repair of a tracheoesophageal fistula, chronic lung disease of infancy, vascular compression of the airway, or mediastinal masses of sufficient firmness to compress the airway. Children with gastroesophageal reflux, or aspiration from above, have an increased incidence of tracheomalacia. The problem in this last situation is trying to decide which condition is the cause and which is the effect.
International
Data from the Sophia Children's Hospital in Rotterdam (southwest Netherlands), the only facility in that country performing bronchoscopy in children, suggest an incidence rate of 1 case per 2100 newborns. [1]
Mortality/Morbidity
Morbidity and mortality are extremely rare. On occasion, tracheomalacia causes enough obstruction to necessitate intervention. This obstruction generally takes the form of episodic severe airway obstruction causing cyanosis. When infants with chronic lung disease of infancy become irritated, they may have what has been called a "BPD fit." This episode usually involves a cry, with either a breath hold or with a sufficient increase in intrathoracic pressure to partially occlude the airway. If the child has tracheomalacia, the frequency and severity of these episodes is often increased.
Race
No racial predilections are known.
Sex
No gender predilections are known.
Age
Because most cases of tracheomalacia appear to be related to a developmental defect in the cartilage of the tracheal wall, the lesion typically occurs in infants and young children. In most children, the tracheal cartilage normalizes, the airway enlarges, and symptoms resolve by 3 years of age (in many before age 1 y).
Because tracheoesophageal fistula is usually repaired early in life, the associated tracheomalacia also appears in early infancy, usually shortly after surgery.
If the tracheomalacia is a result of compression, the patient's age at presentation depends on the cause of compression. Vascular rings, present from birth, cause tracheomalacia early in life. Other causes of compression, especially tumors, occur later in life.
Prognosis
A study that included 55 pediatrics patients diagnosed with tracheomalacia and bronchomalacia reported that severe malacic lesions indicated surgical intervention and worse clinical outcomes for patients with tracheomalacia and bronchomalacia who had acute life-threatening events and extubation failure. [2]
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Slide tracheoplasty and left PA sling repair. Procedure performed by Giles Peek MD, FRCS, CTh, FFICM, The Children’s Hospital at Montefiore, Bronx, NY.
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This shows the trachea during inspiration and expiration. Tracheal collapse of more than 50% during expiration is diagnostic of tracheomalacia.
