What are the causes of tracheal wall collapse, particularly in older adults or those with a history of chronic respiratory diseases like Chronic Obstructive Pulmonary Disease (COPD) or cystic fibrosis?

Causes of Tracheal Wall Collapse

Tracheal wall collapse results from loss of cartilaginous integrity and structural weakness of the airway walls, with the most common causes in adults being COPD, endotracheal intubation injury, chronic airway infection, and collagen disorders. 1

Primary Etiologic Categories

Acquired Causes (Most Common in Adults)

Chronic Obstructive Pulmonary Disease (COPD) is the most common cause of adult tracheomalacia, though the airway collapse seen in COPD patients does not represent true tracheobronchomalacia from cartilage loss. 1, 2 ECAC is present in 35-39% of stable COPD patients and during acute exacerbations. 3

Endotracheal Intubation and Mechanical Ventilation cause pressure necrosis of tracheal cartilage, particularly in prolonged intubation cases. 1 The mechanisms include:

• Barotrauma from positive-pressure ventilation 1
• Direct pressure injury to cartilage from the endotracheal tube cuff 1
• Mucosal injury from deep suctioning techniques causing granulation tissue formation 1
• Airway deformation occurs at pressures as low as 10 cm H2O CPAP or 25 cm H2O peak pressure 1

Chronic or Recurrent Airway Infection leads to cartilage degradation through persistent inflammation. 1

Radiation Therapy to the chest causes cartilage damage and subsequent airway weakness. 1

Connective Tissue and Systemic Disorders

Collagen disorders that cause tracheal collapse include:

• Relapsing polychondritis 1
• Ehlers-Danlos syndrome 1
• Cutis laxa 1
• Marfan syndrome 1

Tracheobronchomegaly represents abnormal dilation and subsequent collapse tendency. 1

External Compression Causes

Pressure from adjacent structures can lead to secondary collapse:

• Thyroid lesions 1
• Vascular anomalies and vascular rings 1
• Hypertensive enlarged pulmonary arteries 1
• Mediastinal masses 1

Trauma

Direct airway trauma from blunt or penetrating chest injury damages cartilaginous support structures. 1

Special Considerations in Pediatric Populations

In infants with chronic lung disease, tracheobronchomalacia occurs in 45% and bronchomalacia in 34% of cases. 1 The immature airway has high compliance that normally decreases threefold between late gestation and birth, making premature infants particularly vulnerable to pressure-induced deformation. 1

Important Clinical Pitfalls

Do not confuse excessive dynamic airway collapse (EDAC) with true tracheomalacia. EDAC involves excessive invagination of the posterior membranous wall without cartilage loss, while tracheomalacia involves actual cartilaginous structural failure. 4, 5 Both produce similar symptoms but have different underlying pathophysiology.

The collapsibility is dynamic over time, not static. In one study, 45% of patients showed improvement in tracheal collapse at follow-up, 35% showed progression, and 20% remained unchanged, indicating this is not necessarily a progressive condition. 6

COPD-associated airway collapse warrants separate consideration as it does not represent true tracheobronchomalacia from cartilage loss but rather dynamic collapse from increased expiratory pressures and airway inflammation. 1, 2

Risk Factors Requiring Heightened Suspicion

• Female sex (particularly for idiopathic laryngotracheal stenosis) 1
• History of prolonged mechanical ventilation, especially in premature neonates with birth weight <1000g 1
• Aggressive suctioning techniques using deep rather than shallow catheter insertion 1
• Use of high-frequency jet ventilation 1
• Morbid obesity (increases intrathoracic pressure swings) 5