How can the mechanism of bronchoscopy (bronchoscopy) cause pneumothorax, especially in patients with pre-existing lung conditions such as chronic obstructive pulmonary disease (COPD) or cystic fibrosis?

Mechanisms of Bronchoscopy-Related Pneumothorax

Pneumothorax during bronchoscopy occurs primarily through direct mechanical disruption of the visceral pleura during transbronchial biopsy, creating a communication between the airway and pleural space that allows air to leak into the pleural cavity. 1

Primary Mechanism: Direct Pleural Injury

The most common mechanism involves transbronchial biopsy (TBB) penetrating through the bronchial wall and visceral pleura, creating a defect that permits air entry into the pleural space. 1 This occurs in 1-5% of transbronchial biopsy procedures, with approximately 50% requiring chest tube drainage. 1, 2

Anatomical Risk Factors

• Upper lobe biopsies carry significantly higher pneumothorax risk (OR 3.3 for left upper lobe specifically), likely due to thinner pleura and greater pleural proximity to airways in these regions. 3, 4
• The right upper lobe is the most common biopsy location (28.7% of cases), contributing to overall pneumothorax frequency. 3

Secondary Mechanisms

Barotrauma from Increased Intrathoracic Pressure

Vigorous coughing during the procedure can cause interstitial air dissection, where increased intrathoracic pressure forces air through alveolar walls into the interstitium, tracking along bronchovascular bundles to the pleural surface. 5 This mechanism can occur even without biopsy, as demonstrated in rare cases of bilateral pneumothorax following bronchoalveolar lavage alone. 5

Delayed Tissue Flap Mechanism

A tissue flap created during biopsy can act as a one-way valve, obstructing airflow during exhalation while allowing air entry during inhalation, progressively accumulating air in the pleural space. 6 This explains delayed pneumothorax presentations occurring 24-48 hours post-procedure. 6

Impaired Wound Healing

Delayed pneumothorax (>4 hours post-procedure) occurs when a visceral pleural defect fails to seal properly due to:

• Chronic steroid use impairing tissue repair 6
• Underlying malignancy causing poor wound healing 6
• Immunosuppression from chronic infections or medications 6
• Blood clot fibrinolysis at the biopsy site, reopening the pleural communication 6

Risk Amplification in Pre-existing Lung Disease

COPD and Emphysema

Patients with emphysema face increased pneumothorax risk due to pre-existing bullae and weakened alveolar walls that are more susceptible to rupture during airway manipulation or positive pressure. 6 The combination of fragile lung parenchyma and procedural trauma creates higher vulnerability.

Cystic Fibrosis

Chronic inflammation and tissue remodeling in cystic fibrosis create friable airways and pleural adhesions that increase both the likelihood of pleural injury during biopsy and impaired healing afterward. 6

Mechanically Ventilated Patients

Pneumothorax incidence increases dramatically to 14% in mechanically ventilated patients undergoing transbronchial biopsy, compared to 3.5% in spontaneously breathing patients. 1, 2 Positive pressure ventilation forces air through any pleural defect more aggressively than negative pressure spontaneous breathing.

Clinical Pitfalls

• Fluoroscopy does not reduce pneumothorax risk during transbronchial biopsy in diffuse lung disease, contrary to common assumptions. 1
• Delayed pneumothorax can occur 24-48 hours post-procedure, requiring patient education about returning for dyspnea or chest pain even after discharge. 2, 6
• Bilateral pneumothorax, though rare, can occur without biopsy through barotrauma mechanisms alone. 5
• Patients on opioid pain medications have increased iatrogenic pneumothorax risk, possibly through respiratory depression and altered breathing mechanics. 6