Tracheobronchomalacia

Epidemiology

  • History: earliest references to tracheomalacia are from the 1930’s-1940’s, describing congenital thoracic vascular abnormalities which resulted in tracheal obstruction
  • Prevalence: acquired tracheobronchomalacia is more common than congenital tracheobronchomalacia
  • Tracheomalacia is Often Associated with Bronchomalacia in Pediactric Populations [MEDLINE]
  • Age/Sex: tracheobronchomalacia is more common in males >40 y/o
    • Male Predominance in Acquired Tracheobronchomalacia

Conditions Associated with Tracheobronchomalacia

  • Bronchopulmonary Dysplasia (BPD) (see Bronchopulmonary Dysplasia, [[Bronchopulmonary Dysplasia]]): occurs in up to 52% of infants with tracheomalacia
  • Cardiovascular Abnormalities: occur in 20-58% of patients with tracheomalacia
    • Abnormalities of the Aortic Arch
    • Atrial Septal Defect (ASD) (see Atrial Septal Defect, [[Atrial Septal Defect]])
    • Dextrocardia (see Dextrocardia, [[Dextrocardia]])
    • Hypoplastic Left Heart
    • Hypoplastic Right Heart
    • Patent Ductus Arteriosus (PDA) (see Patent Ductus Arteriosus, [[Patent Ductus Arteriosus]])
    • Tetralogy of Fallot
    • Valvular Stenosis
    • Ventricular Septal Defect (VSD) (see Ventricular Septal Defect, [[Ventricular Septal Defect]])
  • Gastroesophageal Reflux Disease (GERD) (see Gastroesophageal Reflux Disease, [[Gastroesophageal Reflux Disease]]): 50% of infants with tracheomalacia have GERD
    • GERD has been reported in up to 78% of patients with life-threatening tracheomalacia
  • Immature Autonomic Nervous System
  • Laryngomalacia
  • Neurologic impairment: occurs in 8 to 48% of infants with tracheomalacia
  • Severe Developmental Delay: occurs in 26% of infants with tracheomalacia
  • Subglottic Stenosis
  • Vocal Cord Paralysis

Etiology of Tracheobronchomalacia

Congenital (Primary) Tracheobronchomalacia

General Comments

  • Congenital Tracheomalacia is the most Common Congenital Anomaly of the Trachea: occurs in approximately 1:2100 children

Congenital Abnormalities of Cartilage

  • Dyschondroplasia/Chondromalacia/Chondrodysplasia
    • Physiology: abnormal cartilaginous matrix of the trachea
  • Polychondritis
    • Physiology: abnormal cartilaginous matrix of the trachea

Congenital Anomalies Associated with Tracheobronchomalacia

  • Bronchopulmonary Dysplasia (BPD) (see Bronchopulmonary Dysplasia, [[Bronchopulmonary Dysplasia]])
  • Esophageal Atresia With/Without Laryngeal Cleft
    • Physiology: likely related to embryonic foregut developmental abnormality
      • Idiopathic primary tracheomalacia has been considered the result of a defective foregut division that was not severe enough to cause tracheoesophageal fistula or esophageal atresia, but did result in an inherent weakness of the tracheal wall [MEDLINE]
  • Tracheoesophageal Fistula (TEF) (see Tracheoesophageal Fistula, [[Tracheoesophageal Fistula]])
    • Epidemiology: disease which is most commonly associated with tracheomalacia
    • Physiology: likely related to embryonic foregut developmental abnormality
      • Idiopathic primary tracheomalacia has been considered the result of a defective foregut division that was not severe enough to cause tracheoesophageal fistula or esophageal atresia, but did result in an inherent weakness of the tracheal wall [MEDLINE]

Congenital Syndromes Associated with Tracheobronchomalacia

  • 11p13 Deletion
  • 22q11 Deletion
  • 18–22 Translocation
  • Antley-Bixler Syndrome
  • Atelosteogenesis Type 1
  • Brachmann-de Lange Syndrome
  • Camptomelic Dysplasia
  • CHARGE syndrome
  • Deletion of 12q
  • Diamond-Blackfan Syndrome
  • DiGeorge Syndrome
  • Hallermann-Streiff Syndrome
  • Kniest Dysplasia
  • Larsen Syndrome/Larsen-Like Syndromes
  • Mucopolysaccharidoses
  • Pfeiffer Syndrome
  • Pierre-Robin Syndrome
  • Trisomy 9
  • Trisomy 21
  • VATER Anomaly
  • Williams-Campbell Syndrome

Other

  • Mounier-Kuhn Syndrome (Idiopathic Giant Trachea) (see Mounier-Kuhn Syndrome, [[Mounier-Kuhn Syndrome]])
    • Epidemiology: diagnosed in up to 75% of cases after 28 y/o -> the majority of cases are diagnosed in the 3rd-4th decades of life
      • The majority of patients have few symptoms in childhood and adolescence
    • Physiology: atrophy of the longitudinal elastic fibers and thinning of the muscularis mucosa
    • Diagnosis: tracheobronchomegaly with extension into the central bronchi (with normal peripheral airway diameter)
    • Clinical
      • Bronchiectasis (see Bronchiectasis, [[Bronchiectasis]])
      • Chronic Accumulation of Secretions
      • Pulmonary Fibrosis
      • Recurrent Infections
      • Tracheal Diverticuli
    • Criteria for Airway Enlargement (Based on Being >3 Standard Deviations Above the Upper Limits of Normal in Adults)
      • Tracheal Diameter: >3.0 cm
      • Right Mainstem Bronchial Diameter: >2.4 cm
      • Left Mainstem Bronchial Diameter: >2.3 cm
  • Prematurity
  • Pulsatile Tracheal Collapse with Normal Innominate Artery
  • Idiopathic Tracheobronchomalacia
    • Epidemiology: occurs in otherwise healthy infant

Acquired (Secondary) Tracheobronchomalacia

General Comments

  • Acquired Tracheomalacia is More Common Than Congenital Tracheomalacia in Adult Cases
  • Intubation/Tracheostomy are the Most Common Etiologies of Secondary Tracheomalacia

Chronic Extrinsic Tracheal Compression

  • Abscess
  • Cardiac Structure
    • Left Atrial Enlargement/Hypertrophy
  • Post-Traumatic
  • Skeletal Structur
  • Tumor/Cyst
    • Bronchogenic Cyst (see Bronchogenic Cyst, [[Bronchogenic Cyst]])
    • Cystic Hygroma
    • Enterogenic Cyst
    • Goiter (see Goiter, [[Goiter]])
      • Epidemiology: common etiology of tracheal compression
      • Physiology: mediastinal goiter with compression of trachea
    • Hemangioma
    • Lymphatic Malformation
    • Lymphoma (see Lymphoma, [[Lymphoma]])
    • Neuroblastoma (see Neuroblastoma, [[Neuroblastoma]])
    • Teratoma (see Teratoma, [[Teratoma]])
    • Thymic Enlargement
    • Thymoma (see Thymoma, [[Thymoma]])
  • Vascular Ring/Structure
    • Epidemiology
      • Uncommon: comprise <1% of all cardiovascular malformations
      • Sex: M = F
      • Relative Frequency: double aortic arch and right aortic arch with ligamentum arteriosum account for 85-95% of all vascular ring cases
    • Physiology: tracheal compression by a vascular malformation (which was undiagnosed from childhood)
      • Aberrant Right Subclavian
      • Abnormal Take-Off of the Innominate Artery
      • Anomaly of Left Pulmonary Artery
      • Aortic Aneurysm (see Thoracic Aortic Aneurysm, [[Thoracic Aortic Aneurysm]])
      • Double Aortic Arch
      • Enlarged Pulmonary Veins
      • Right Aortic Arch with Left Ligamentum Arteriosum
    • Clinical: symptoms usually start in infancy or early childhood (but may start later)
      • Dysphagia (see Dysphagia, [[Dysphagia]]): may occur when esophagus is also compressed

Trauma

  • External Chest Trauma
    • Physiology: traumatic tracheal cartilaginous injury
  • Post-Intubation
    • Risk Factors
      • Concurrent High-Dose Corticosteroid Therapy (see Corticosteroids, [[Corticosteroids]])
      • Prolonged Intubation
      • Recurrent Intubation
    • Physiology: damage to tracheal cartilage at inflatable cuff site due to pressure necrosis, impaired blood flow, recurrent infection, mucosal friction, or mucosal inflammation
    • Clinical: usually segmental (maximum length is usually 3 cm)
  • Post-Tracheostomy (see Tracheostomy, [[Tracheostomy]])
    • Physiology: damage to tracheal cartilage at stoma/cuff/distal tube sites due to pressure necrosis, impaired blood flow, recurrent infection, mucosal friction, or mucosal inflammation
    • Clinical: usually segmental (maximum length is usually 3 cm)

Other

  • Chronic Obstructive Pulmonary Disease (COPD) (see Chronic Obstructive Pulmonary Disease, [[Chronic Obstructive Pulmonary Disease]])
    • Physiology: believed to be related to recurrent infections or inhalation of irritants (tobacco smoke)
  • Cystic Fibrosis (CF) (see Cystic Fibrosis, [[Cystic Fibrosis]])
    • Physiology: believed to be related to recurrent infection
  • Gastroesophageal Reflux Disease (GERD) (see Gastroesophageal Reflux Disease, [[Gastroesophageal Reflux Disease]]) [MEDLINE]
  • Post-Lung/Post-Heart-Lung Transplant (see Lung Transplant, [[Lung Transplant]])
    • Physiology: tracheal cartilaginous injury
  • Post-Pneumonectomy
  • Relapsing Polychondritis (see Relapsing Polychondritis, [[Relapsing Polychondritis]])
    • Epidemiology: nearly 50% of patients with relapsing polychondritis have some degree of tracheomalacia
      • Severe airway manifestations are 3x more common in female relapsing polychondritis cases
    • Physiology: tracheal cartilaginous destruction
    • Treatment/Prognosis: cases with respiratory complications have worse prognosis and poorer response to corticosteroids
  • Severe/Recurrent Tracheobronchitis (see Acute Bronchitis, [[Acute Bronchitis]])
  • Sulfur Mustard Gas Exposure (se Sulfur Mustard Gas, [[Sulfur Mustard Gas]]) [MEDLINE]

Physiology

Definitions

  • Malacia: softness (generally of cartilage or bone)

Normal Tracheal Function

  • Trachea is Compliant, Allowing the Normal Intrathoracic Trachea to Dilates with Inspiration and Narrow with Expiration: this occurs due to the difference between intrathoracic and tracheal intraluminal pressures
  • Specific Maneuvers Where Intrathoracic Pressure is Significantly Greater Than Tracheal Intraluminal Pressure
    • Cough
    • Forced Expiration
    • Valsalva Maneuver

Tracheomalacia

  • Abnormal Diffuse or Segmental Weakening of Intrathoracic Tracheal Wall: due to intrathoracic pressure is exceeding the tracheal intraluminal pressure, resulting in exaggerated tracheal narrowing during expiration (and widening during inspiration
    • More Common Type
    • Mechanisms
      • Cartilaginous Malacia: associated with cartilaginous softening
      • Membranous Malacia with Excessive Forward Displacement of the Membranous Wall (Excessive Dynamic Airway Collapse): reduction and/or atrophy of the longitudinal elastic fibers of the pars membranacea
  • Abnormal Diffuse or Segmental Weakening of Extrathoracic Tracheal Wall: due to negative intrapleural pressure being transmitted to the extrathoracic trachea (due to pleural reflections), resulting in upper airway collapse during inspiration
    • Less Common Type

Clinical Classification Based on Appearance

  • Lateral: lateral tracheal narrowing (“saber-sheath trachea”)
  • Crescent: anteroposterior tracheal narrowing (“scabbard shape”)
  • Circumferential: anteroposterior and lateral tracheal narrowing

Clinical Classification Based on General Distribution

  • Segmental
  • Diffuse

Clinical Classification Based on Specific Anatomic Distribution

  • Tracheal
  • Bronchial
  • Tracheobronchial

Bronchomalacia

  • Weakening of Bronchial Wall: results in exaggerated bronchial narrowing during expiration and widening during inspiration
    • Isolated Bronchomalacia is Far Less Common Than Tracheobronchomalacia

Tracheobronchomalacia

  • Diffuse or Segmental Weakening of the Tracheal Wall Extending Into One or Both Mainstem Bronchi: results in exaggerated tracheobronchial narrowing during expiration and widening during inspiration

Diagnosis

Chest X-Ray (see Chest X-Ray, [[Chest X-Ray]])

  • Usually Not Diagnostic, as Airway Narrowing is Dynamic

Dynamic Chest CT (see Chest Computed Tomography, [[Chest Computed Tomography]])

  • Reported Accuracy Rates of Dynamic CT for Tracheomalacia: 97%
  • Dynamic CT Technique for Diagnosis of Tracheomalacia: airways are measured in cross-section on end-expiratory images

Dynamic MRI During Forced Expiration/Cough

  • Has Been Used, But Role is Currently Unclear

Pulmonary Function Tests (PFT’s) (see Pulmonary Function Tests, [[Pulmonary Function Tests]])

  • Flow-Volume Loop [MEDLINE]: low peak expiratory flow rate, followed by rapid decrease in flow
    • Low FEFmax: 82% of cases
    • Biphasic Morphology: 20% of cases
    • Notched Expiratory Loop: 9% of cases
    • Expiratory Oscillations: 3% of cases
    • No Distinctive Abnormality: 17% of cases
  • Patterns in Moderate-Severe Tracheobronchomalacia [MEDLINE]
    • Obstruction: 44% of cases
    • Restriction: 18% of cases
    • Mixed: 17% of cases
    • Normal: 21% of cases

Bronchoscopy (see Bronchoscopy, [[Bronchoscopy]])

  • Diagnostic Gold Standard: to demonstrate dynamic tracheobronchial collapse
  • Technique: bronchoscopy is performed with minimal sedation (allowing patient to follow instructions)
  • Criteria for Tracheomalacia: >50% narrowing (although trials suggest that many normals may reach this diagnostic threshold)

Clinical Manifestations of Tracheobronchomalacia

General Comments

  • Asymptomatic: some cases
  • Misdiagnosis of Tracheobronchomalacia: tracheobronchomalacia may be misdiagnosed as asthma
  • Most Cases of Congenital Tracheomalacia Manifest During Early Childhood: usually manifest during first weeks-months of life
    • These are usually due to inherited diseases which weaken the tracheal wall (such as polychondritis)
  • Expected Course of Disease
    • Adult Patients: in most cases, tracheomalacia is progressive over time
    • Pediatric Cases (Healthy and Most Premature Infants): primary trachoemalacia is usually a self-limiting disease -> most infants outgrow the condition by 2 y/o
    • Pediatric Cases with Congenital Syndromes: tracheomalacia often persists and may be fatal in some cases
  • Precipitants of Clinical Symptoms
    • Active Infection
    • General Anesthesia
    • Progression of Airway Narrowing
    • Weaning from Mechanical Ventilation: removal of positive pressure (which had been splinting the airway open) may result in unmasking of the symptoms

Pulmonary Manifestations

  • Atelectasis (see Atelectasis, [[Atelectasis]]): may occurs in cases with bronchomalacia
  • Bronchiectasis (see Bronchiectasis, [[Bronchiectasis]])
  • Chronic Accumulation of Secretions
  • Chronic Hypoventilation (see Chronic Hypoventilation, [[Chronic Hypoventilation]])
  • Cough with Sputum Production (see Cough, [[Cough]]): cough may be paroxysmal or barking in character
    • Syncope: may occur with forced exhalation or cough
  • Dyspnea (see Dyspnea, [[Dyspnea]])
  • Episodic Choking
  • Hemoptysis (see Hemoptysis, [[Hemoptysis]])
  • Localized Wheeze: may be heard in cases with localized bronchomalacia
  • Stridor (see Stridor, [[Stridor]]): may occur with inspiration
  • Maneuvers Which May Elicit Signs of Tracheomalacia
    • Forced Expiration
    • Recumbency
    • Valsalva Maneuver
  • Pulmonary Fibrosis
  • Recurrent Respiratory Infection
  • Tracheal Diverticuli: due to increased tracheal wall compliance and redundant membranous tissue

Treatment

Infant Cases

  • Development of Normal Cartilage Usually Occurs Between 6 mo-2 y/o

General Measures

Optimization of Chronic Obstructive Pulmonary Disease (COPD) Management

  • Rationale: serves to decrease bronchospasm and intrathoracic pressure fluctuations (which worsen central airway collapse)
  • Bronchodilators
  • Flutter Valve: may facilitate secretion clearance
  • Pursed Lip Breathing Technique: may be useful

Treatment of Relapsing Polychondritis (see Relapsing Polychondritis, [[Relapsing Polychondritis]])

  • Rationale: may decrease airway inflammation and slow progression

Treatment of Gastroesophageal Reflux Disease (GERD) (see Gastroesophageal Reflux Disease, [[Gastroesophageal Reflux Disease]])

  • Rationale: may decrease airway inflammation and slow progression

Silicone Tracheal/Bronchial Stents

  • Indications: anatomic narrowing amenable to stent placement
  • Technique: inserted via rigid bronchoscopy
    • Note: metal stents are contraindicated for benign airway obstructive processes, such as tracheomalacia
  • Monitoring
  • Assessment for Clinical Improvement
    • Clinical Improvement with Stent: consideration of surgical repair vs long-term stenting
    • Lack of Clinical Improvement with Stent: stent should be removed
  • Adverse Effects
    • Mucous Plugging of Stent: use of ultrasonic saline nebulization may mitigate this complication
    • Stent Migration

Positive Pressure Therapy

  • Continuous Positive Airway Pressure (CPAP) (see Continuous Positive Airway Pressure, [[Continuous Positive Airway Pressure]]): can maintain an open airway and facilitate secretion drainage
    • However, CPAP has not been shown to have a long-term benefit in terms of cough or dyspnea
  • Bilevel Positive Airway Pressure (BPAP): may be useful for cases with chronic hypercapnic respiratory failure

Tracheostomy (see Tracheostomy, [[Tracheostomy]])

  • Indications: may be useful in cases where narrowing is proximal to the tracheal stoma
  • Tracheostomy may also be beneficial as a route to deliver positive airway pressure
  • However, since tracheostomy may itself further damage the trachea, it is not considered a first-line therapy

Surgical Repair

  • Indications: may be required in some cases
  • Conventional Resection/Reconstruction: most useful in the cervical trachea
  • Tracheal Replacement [MEDLINE]: investigational
  • Tracheobronchoplasty

References

  • Treatment of tracheomalacia: eight years’ experience. J Pediatr Surg 1986; 21:781–785 [MEDLINE]
  • Nasal continuous positive airway pressure in the treatment of tracheobronchomalacia. Am Rev Respir Dis 1993; 147:457-461 [MEDLINE]
  • The prevalence of gastroesophageal reflux in children with tracheomalacia and laryngomalacia. Chest. 2001;119(2):409 [MEDLINE]
  • Tracheomalacia and bronchomalacia in children: incidence and patient characteristics. Chest. 2005;128(5):3391 [MEDLINE]
  • Tracheomalacia and tracheobronchomalacia in children and adults: an in-depth review. Chest. 2005;127(3):984-1005 [MEDLINE]
  • Tracheobronchomalacia and air trapping after mustard gas exposure. Am J Respir Crit Care Med. 2006;173(3):304 [MEDLINE]
  • Airway stabilization with silicone stents for treating adult tracheobronchomalacia: a prospective observational study. Chest 2007;132:609-616 [MEDLINE]
  • Tracheobronchomalacia in adults. Semin Thorac Cardiovasc Surg. 2010 Summer;22(2):165-73. doi: 10.1053/j.semtcvs.2010.07.001 [MEDLINE]
  • Pulmonary function and flow-volume loop patterns in patients with tracheobronchomalacia. Respir Care. 2013 Sep;58(9):1521-6. Epub 2013 Mar 12 [MEDLINE]
  • The first tissue-engineered airway transplantation: 5-year follow-up results. Lancet 2014;383:238-244 [MEDLINE]