Tracheomalacia

Descriptive text is not available for this imageBASICS

DESCRIPTION

  • Dynamic collapse of trachea due to excessive increase in compliance of the trachea
  • Tracheomalacia (TM) or tracheobronchomalacia (TBM) may be generalized or localized.

EPIDEMIOLOGY

  • Most common congenital tracheal anomaly
  • Estimated incidence of primary airway malacia is 1 in 2,100.
  • Prevalence of TM
    • Infants with bronchopulmonary dysplasia (BPD) is 16%.
    • Infants with esophageal atresia (EA) is 11–33%.

ETIOLOGY

  • Congenital or primary TM
    • Occurs due to weakening of the tracheal wall due to abnormal formation or maturation of the airway
    • Causes: isolated or associated with other airway anomalies
      • Idiopathic
      • Cartilage congenital abnormalities (dyschondroplasia, polychondritis, Ehlers-Danlos syndrome)
      • Congenital syndromes (CHARGE [coloboma, heart defects, atresia choanae, growth retardation, genital abnormalities, and ear abnormalities], VATER [vertebrae, anus, trachea, esophagus, and renal anomalies], trisomy 9 and 21, Crouzon, Diamond-Blackfan, DiGeorge, Robin sequence)
      • Congenital anomalies due to improper foregut separation of the trachea from the esophagus (tracheoesophageal fistula [TEF], laryngotracheoesophageal clefts, EA)
  • Acquired or secondary TM
    • Occurs in the normally developed trachea after insult
      • Tracheostomy: most common cause of acquired extrathoracic TM (10%)
      • Prolonged intubation
      • Severe tracheobronchitis
      • Compression-vascular, cardiac, skeletal, tumors, and cysts
      • Infection

RISK FACTORS

Prematurity is a risk factor for acquired intrathoracic TM.

PATHOPHYSIOLOGY

  • Trachea and main bronchi are supported by rigid C-shaped cartilages anteriorly and laterally and by a short posterior membrane (pars membranacea).
  • During normal breathing, expiratory recoil pressure of the chest wall leads to dynamic increase in intrathoracic pressure, which is transmitted to the airways.
  • TM occurs either due to
    • Reduction or atrophy of the longitudinal elastic fibers of the pars membranacea (posterior wall of the trachea) or
    • Structural anomalies of the tracheal cartilage
  • Intrathoracic TM
    • Increased compliance of the central airway within the thorax → excessive dynamic collapse during exhalation
  • Extrathoracic TM
    • Dynamic collapse of the airway between glottis and sternal notch
    • Occurs during inhalation rather than exhalation

Descriptive text is not available for this imageDIAGNOSIS

HISTORY

  • Symptoms may be delayed until 2 to 3 months of age in case of primary TM.
  • Ranges from minor wheezing, stridor, barking cough, and feeding difficulties to severe respiratory distress and brief, resolved unexplained events (BRUE)
  • Intrathoracic TM: expiratory symptoms including wheezing, barking/brassy cough; prolonged expiratory phase
  • Extrathoracic TM: inspiratory symptoms including stridor, prolonged inspiratory phase
  • Symptoms worse during periods of increased respiratory effort: crying, agitation, feeding, and infection.

PHYSICAL EXAM

  • Intrathoracic TM: homophonous or monophonic wheezing
  • Extrathoracic TM: high-pitched inspiratory stridor

DIFFERENTIAL DIAGNOSIS

  • Suboptimally controlled asthma
  • Tracheal stenosis
  • Recurrent TEF
  • Gastroesophageal reflux disease (GERD)
ALERT

Careful distinction must be made between TM, recurrent TEF, and severe GERD because all of them can coexist and each alone can present similar symptoms.

DIAGNOSTIC TESTS & INTERPRETATION

  • Bronchoscopy
    • Direct visualization of airway by dynamic airway bronchoscopy is the diagnostic tool of choice.
    • >50% narrowing of the lumen during spontaneous breathing is diagnostic of TM/TBM.
      • Mild (50–75%)
      • Moderate (75–90%)
      • Severe (90%)
  • Multidetector computed tomography (CT)
    • Requires patient participation and exposure to radiation
    • Provides perioperative information about associated tracheal and intrathoracic vascular anomalies
  • Dynamic magnetic resonance imaging (MRI)
    • To evaluate for extrinsic airway vascular compression
  • Pulmonary function testing classically shows reduction in peak expiratory flow; however, this is not specific for TM.
  • Other studies
    • Patients with apneic spells require careful cardiac and neurologic evaluations to exclude cardiac and neurologic etiologies.
    • Preoperative assessment:
      • Esophagram to assess swallowing, strictures, and aspiration
      • Ventilation perfusion scan to assess lung performance in case of associated congenital anomalies
      • Echocardiogram to check for external compression as from a double aortic arch or vascular ring

Descriptive text is not available for this imageTREATMENT

  • Pharmacotherapy
    • Pharmacotherapy is directed to increase the tone of the trachealis muscle and to optimize ciliary clearance of airway secretions.
    • Anticholinergic agent—ipratropium bromide (Atrovent®) to minimize secretions and to stimulate smooth muscle contraction
    • Muscarinic agonist (bethanechol) directly stimulates the airway smooth muscle and increases the posterior membrane tone.
    • Airway clearance: pulmonary hygiene and chest physiotherapy to prevent recurrent chest infections
    • β-Agonist worsens TM/TBM by reducing the tone of airway smooth muscle.
    • Management of comorbidities (GERD, eosinophilic esophagitis).
    • Continuous positive airway pressure (CPAP) in children with life-threatening episodes of airway obstruction, recurrent infection, respiratory failure, or failure to thrive
  • Surgical
    • Surgical indications: severe TM causing dying spells, recurrent pneumonia, intermittent respiratory obstruction, inability to extubate malacic airway
    • Aortopexy (suspending anterior trachea): treatment of choice for severe TM
    • It is recommended to repair recurrent TEF, correct TM, and perform antireflux surgery in this order if these three abnormalities occur in the same patient.
    • Short segment: Consider tracheal resection with end-to-end anastomosis or slide tracheoplasty.
    • Tracheopexy (anterior or posterior), internal stenting, external airway splinting in selected patients
    • Tracheostomy: indicated in severe TM to bypass obstruction
    • Repair of vascular ring and slings in secondary TM

Descriptive text is not available for this imageONGOING CARE

PROGNOSIS

  • Long-term prognosis is excellent in isolated congenital TM.
  • Most affected infants improve spontaneously by 6 to 12 months of age as airway caliber increases and cartilage develops.
  • TM related to foregut malformation or external compression tends to persist later in childhood.

COMPLICATIONS

Excessive collapse of airways results in ineffective cough and impaired ability to expel secretions, which can lead to recurrent severe respiratory infections and bronchiectasis.

ADDITIONAL READING

  • Kamran A , Jennings RW . Tracheomalacia and tracheobronchomalacia in pediatrics: an overview of evaluation, medical management, and surgical treatment. Front Pediatr. 2019;7:512. doi:10.3389/fped.2019.00512  [PMID:31921725]
  • Thomas R , Chang A , Masters IB , et al. Association of childhood tracheomalacia with bronchiectasis: a case-control study. Arch Dis Child. 2022;107(6):565-569. doi:10.1136/archdischild-2021-322578  [PMID:34649867]
  • Thompson DM . Abnormal sensorimotor integrative function of the larynx in congenital laryngomalacia: a new theory of etiology. Laryngoscope. 2007;117(6 pt 2)(suppl 114):1-33. doi:10.1097/MLG.0b013e31804a5750  [PMID:17513991]
  • Wallis C , Alexopoulou E , Antón-Pacheco JL , et al. ERS statement on tracheomalacia and bronchomalacia in children. Eur Respir J. 2019;54(3):1900382. doi:10.1183/13993003.00382-2019

CODES

ICD 10

Q32.0 Congenital tracheomalacia

FAQ

  • Q: What is the expected clinical course for TM?
  • A: Symptoms may persist for several months in primary TM. Resolution will occur as the tone of the posterior membrane of the trachea and the rigidity of the tracheal cartilage increases with age. Symptom resolution in secondary TM is dependent on the cause. Recurrent brassy cough persists after surgical correction.
  • Q: What is “malacia”?
  • A: “Malacia” means an abnormal softening of tissue. The term comes from the Greek word malakos, meaning “soft.”

Authors

Christina J. Yang, MD

Aneela Bidiwala, MD


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