Pediatric Tracheomalacia

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.

As far as tracheomalacia is understood, most cases are isolated and idiopathic. A recent study proposed a possible neurologic etiology for tracheomalacia. This group was caring for a child with increased intracranial pressure. When the pressure was elevated, the child developed tracheomalacia. When the pressure was relieved, the tracheomalacia remitted. This scenario recurred, although the etiology for increased intracranial pressure causing tracheomalacia is unknow.[2]

Transient defects in tracheal cartilage development are assumed to be the cause of this condition. This is sometimes referred to as type 1 tracheomalacia.

Autopsy data are lacking, and no animal model is noted.

Some children with tracheomalacia have the lesion because of vascular anomalies or other causes of compression of the airway. This is referred to as type 2 tracheomalacia.

Tracheomalacia is a common finding after repair of a tracheoesophageal fistula.

Tracheomalacia may occur with and complicate other disorders, including gastroesophageal reflux disease, other forms of recurrent aspiration, and bronchopulmonary dysplasia (chronic lung disease of infancy).

United States statistics

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 statistics

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.[3]

Race-, sex-, and age-related demographics

No racial predilections are known.

No gender predilections are known.

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.

The prognosis is excellent. Most patients outgrow this condition by the time they are aged 3 years; many infants outgrow tracheomalacia before they are aged 1 year.

If gastroesophageal reflux is present, attention to this speeds healing.

Tracheomalacia after tracheoesophageal fistula repair may take longer to heal than primary tracheomalacia. Tracheomalacia after a compressing lesion lasts longer, depending on the length of time of the compression.

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.[4]

Morbidity/mortality

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.

Complications

Severe obstruction requires acute intervention with mechanical ventilation or positive pressure.

Chronic obstruction necessitates surgical intervention (eg, tracheostomy, stent placement, aortopexy).

Aortopexy and stent placement have been compared over a 10-year followup.[5]  Both are equally effective in improving symptoms and allowing for normal growth and development. Aortopexy is associated with more perioperative complications, whereas stents are associated with long-term complications and the need for removal.

A case-control study by Thomas et al demonstrated that children with tracheomalacia are at increased risk of developing bronchiectasis (adjusted odds ratio [OR], 13.2). For those with tracheomalacia that meets the definition established by the European Respiratory Society (greater than 50% expiratory reduction in the cross-sectional luminal area), the risk is even higher (adjusted OR, 24.4).[6]

The history of a patient with tracheomalacia typically includes a wheeze that usually begins when the individual is aged 4-8 weeks. Although the congenital lesion is present before this time, airflow is apparently insufficient during the first few weeks of life to generate abnormal sounds. The wheeze generally increases with activity and colds and decreases during quiet periods.

At first, wheezing may be mistaken for a sign of bronchiolitis, especially during respiratory syncytial virus season. As wheezing continues, it may be mistaken for that of asthma or cystic fibrosis. If bronchodilator therapy has been attempted, the history usually indicates no improvement; however, in some infants, tracheomalacia worsens with bronchodilator therapy.

Unlike most infants with asthma or cystic fibrosis, infants with tracheomalacia are described as "happy wheezers" (ie, they maintain normal oxygenation and disposition and grow and develop normally, despite the chronic airway noises).

The physical findings suggest the diagnosis.

The baby looks well and happy despite the chronic wheeze.

Vital signs, including the patient's respiratory rate and oxygen saturation, are normal.

Lungs have good air entry. The typical abnormality is of a wheeze throughout exhalation that sounds the same in all lung fields. It is a coarse monophonic exhalatory sound, which has been described as exhalatory stridor. No asymmetry to the breath sounds is present. On occasion, the lesion is intrathoracic, and the airway sounds occur in inspiration.

The patient's voice and cry are normal, unless gastroesophageal reflux is present.

Because some children have concomitant laryngomalacia, abnormal sounds may be heard on inspiration.

Laboratory studies

Oxygen saturation should be assessed in tracheomalacia.

Fluoroscopy and radiography

The diagnosis can often be confirmed by performing fluoroscopy of the airway.

During the study, the pediatric radiologist observes the airway collapsing and opening up. This finding may appear on anteroposterior images, on which the tracheal air shadow seems to disappear and reappear with respirations in the affected area of the trachea.

The lesion may be observed most easily on lateral images, on which the anterior and posterior walls of the trachea may be observed apposing dynamically.

Loss of the tracheal air shadow with no respiratory changes suggests static collapse of the airway.

CT scanning

Chest computed tomography (CT) scanning may reveal the abnormal shape of the trachea as the apposition of the walls. "Expiratory frown" shapes are observed in CT scans when the area is scanned during an exhalation or cough.[7]

Chest CT scanning may not reveal the dynamic nature of the lesion and may not depict the lesion at all.

A CT scan, especially one obtained with contrast material, may reveal vascular lesions that mimic tracheomalacia and that may eventually lead to tracheomalacia.

According to a European Respiratory Society (ERS) Task Force report, paired end-inspiratory and end-expiratory multidetector computed tomography (MDCT) or paired end-inspiratory and dynamic expiratory MDCT are both reliable imaging techniques. Compared with laryngoscopy/bronchoscopy, the overall diagnostic accuracy of paired airway MDCT is 91%.[8]

In patients with tracheobronchomalacia, dynamic expiratory CT was shown to elicit a larger degree of airway collapse than standard end-expiratory CT.[9]

Esophagraphy

Esophagraphy can be performed to evaluate for a vascular anomaly, for a bronchogenic cyst, or for esophageal duplication.

Esophagraphy does not assist the physician in making a definitive diagnosis.

The definitive method of diagnosis is bronchoscopy.[10] In one series, when a pediatric pulmonologist suspected tracheomalacia, the correct diagnosis was tracheomalacia in 74% of the cases.[3] However, tracheomalacia was not suspected in 52% of patients who were eventually diagnosed with it.

During bronchoscopy, the anterior wall can be observed to collapse against the posterior wall. At the same time, other lesions can be diagnosed or excluded under direct visualization.

The authors prefer flexible bronchoscopy to confirm the diagnosis. With flexible bronchoscopy, the baby is breathing spontaneously with light anesthesia. This method preserves respiratory dynamics better than rigid bronchoscopy. In addition, the rigid bronchoscope may serve as a stent to the airway, masking the diagnosis.

Confirming the diagnosis is important for differential diagnosis. Otherwise, one or more tests may be unnecessarily considered. A sweat test may be performed to reduce the likelihood of cystic fibrosis. Esophagraphy may be performed to eliminate the likelihood of most of the vascular anomalies. These diagnoses are usually eliminated by bronchoscopy. CT scanning to reduce the likelihood of airway foreign body and other lesions that may be compromising the airway. If bronchoscopy is performed, it is an efficient and direct method of looking for foreign bodies.

If tracheomalacia is diagnosed, a sweat test is not necessary unless other manifestations of cystic fibrosis are present. The adage still holds that a sweat test has no contraindication.

If gastroesophageal reflux is a concern, evaluate this condition by using a pH or impedance probe or esophageal biopsy. If bronchoscopy is performed, bronchoalveolar lavage can be done to assess for lipid-laden macrophages.

After the diagnosis of tracheomalacia is made, the most effective and safest treatment is allowing time to pass ("tincture of time"). Some have recommended that before considering a surgical approach, other therapies, including noninvasive ventilation, should be used, given the transient nature of the disorder.[11]

Bronchodilators do not help and sometimes worsen the tracheomalacia. The tone of the smooth muscle helps stent the airway. Administering a beta-agonist relaxes the smooth muscle and may worsen collapse of the airway.

If the child is having difficulty with retained secretions, chest physiotherapy may be helpful.

If gastroesophageal reflux is present, appropriate pharmacotherapy should be considered.

On occasion, systemic corticosteroids are used when the baby has increased symptoms during an acute respiratory tract infection. These drugs should be reserved for episodes in which the tracheomalacia interferes with the child's oral intake or disposition or when the child develops respiratory difficulty.

If the child is making more noise but is otherwise doing well, steroids can usually be avoided.

One group showed that positive expiratory pressure during an illness improved the cough flow rates in children with tracheomalacia, making the chest physical therapy and cough itself more effective.[12] Continuous positive airway pressure or bilevel positive airway pressure provided by means of tight-fitting face or nasal mask, endotracheal tube, or tracheostomy tube can provide relief from severe obstruction.

Surgery may be an option when the baby has one or all of the following:

• Difficulty gaining weight and developing

• Recurrent pneumonia or apnea

• Enough airway obstruction to require long-term airway support

Tracheostomy can provide internal stenting of the trachea in babies with any of the findings above. With time and growth, the airway obstruction resolves, and the cannula can be removed from the infant.

In aortopexy, the aortic arch is lifted off the trachea. This has resulted in symptomatic improvement in many children.

Recent success with metal stents in young children has been described.[13]

Repair of vascular rings and slings can be done to decompress the trachea and allow healing to begin.

Because the expiratory noise has clinically significant differential diagnoses, refer the baby whose wheeze does not remit with good asthma therapy to a pediatric pulmonologist.

Bronchoscopy ensures a definitive diagnosis in an infant who is otherwise well. A sweat test, esophagraphy, echocardiography, and/or chest CT scanning may otherwise be necessary.

Diet

No dietary restrictions or changes are necessary.

Activity

No restrictions or changes are necessary.

The abnormal airway dynamics may persist even after the clinical findings have remitted. If symptoms persist with exercise as the patient ages, an exercise test is indicated to make sure that minute ventilation increases appropriately with exercise.

Further outpatient care

No specific therapy or precautions are needed.

Provide outpatient care if bronchodilators are considered because they worsen the condition in some patients.

Follow the normal immunization schedule.

Reassurance during acute respiratory illnesses may be necessary. Babies may need to be seen frequently during these illnesses. During an upper respiratory infection, the normal cough sounds more crouplike in these children because the walls of the trachea appose during the cough. This also causes irritation in the tracheal walls, which prolongs the cough. The added pressures to overcome nasal obstruction adds to the dynamic collapse during the infection. As long as the baby is able to achieve adequate oral intake and is acting normally, intervention is usually not necessary.

Further inpatient care

Admission is not necessary unless the baby with tracheomalacia is having respiratory distress.

Inpatient and outpatient medications

No long-term medications are required. Consider systemic corticosteroids during a respiratory tract infection if the baby is having difficulty breathing.

Transfer

If the baby is having severe respiratory distress, transfer him or her to a pediatric intensive care unit.

After the diagnosis of tracheomalacia is made, the most effective and safest treatment is the passage of time. Bronchodilators (eg, albuterol) usually do not help and may worsen tracheomalacia in some infants. The tone of the smooth muscle presumably stents the airway in some babies. Administering a beta-agonist relaxes these muscles and may worsen airway collapse.

Class Summary

These agents have anti-inflammatory properties and cause profound and varied metabolic effects. They modify the body's immune response to diverse stimuli.

Babies who have respiratory difficulties during a concomitant upper respiratory tract infection may respond favorably to systemic corticosteroids. If the baby is noisier than usual but acting and eating normally, do not use medications.

Prednisolone (Orapred, Prelone, Pediapred)

May decrease inflammation by reversing increased capillary permeability and suppressing polymorphonuclear (PMN) activity. Available in tab and syr; prednisolone syr tastes better than prednisone syr.

Prednisone (Deltasone, Meticorten, Orasone)

May decrease inflammation by reversing increased capillary permeability and suppressing PMN activity.