Bullous Emphysema

Emphysema with bullae: air filled spaces in the lung greater than 1 cm in diameter, formed by destruction and coalescence of alveolar septa. A giant bulla occupies more than one third of a hemithorax and compresses adjacent normal lung. Bullae may be single or multiple and may be present in a person with otherwise mild emphysema.

• Causes: tobacco smoking, cannabis smoking (upper lobe bullae in young adults), intravenous drug use (talc), alpha-1 antitrypsin deficiency (lower lobes), HIV infection, connective tissue disease (Marfan syndrome, Ehlers-Danlos syndrome), sarcoidosis, and tuberculosis scarring. Giant bullous emphysema ("vanishing lung syndrome") affects young men who smoke tobacco or cannabis, with asymmetrical upper lobe disease.
• Mechanism: check valve obstruction of small airways and loss of elastic recoil produce progressive distension of the bulla. Compression of surrounding parenchyma reduces ventilation and may impair venous return, producing dyspnoea out of proportion to measured lung function.
• Prevalence of bullae is about 1 to 2% on CT in smokers and higher in COPD. Many are asymptomatic; symptoms depend on the size of the bulla and the state of the adjacent lung. Without surgery giant bullae enlarge slowly over years, and complications occur in about 20 to 30%.

• Progressive breathlessness, cough, chest tightness, and reduced exercise tolerance; some are asymptomatic. Sudden severe chest pain and breathlessness suggest pneumothorax. Haemoptysis suggests infection, cancer in a bulla wall, or a fungal ball.
• Signs: hyperresonance, reduced breath sounds, hyperinflation, reduced cardiac dullness, cachexia in advanced disease; with a pneumothorax, unilateral absent breath sounds and tracheal shift in tension.
• Differential diagnosis: pneumothorax (a giant bulla can mimic a pneumothorax on X-ray, and inserting a drain into a bulla risks a persistent leak and bronchopleural fistula, so use CT to separate them), pneumatocele, lung abscess or cavity (tuberculosis), cystic lung disease (lymphangioleiomyomatosis, Langerhans cell histiocytosis), congenital cystic lesions, hydatid cyst, bronchogenic cyst, and diaphragmatic hernia.
• Complications: pneumothorax (the commonest, about 5 to 10% per year with large bullae), infection of a bulla (cavity with air fluid level), aspergilloma, haemoptysis, lung cancer arising in the bulla wall (risk raised in smokers), compression of adjacent lung with respiratory failure, and rarely tension physiology with cardiovascular compromise.

• Chest X-ray: avascular, hyperlucent space with a thin wall (curved, hairline) and displacement of lung and vessels toward the hilum. Compare with earlier films.
• High resolution CT chest: number, size, distribution of bullae, thickness of the bulla wall, extent of compression of adjacent lung, emphysema in the remaining lung, vessels within and around the bulla, and exclusion of nodules and cancer.
• Pulmonary function: spirometry (obstruction with a reduced FEV1; FEV1 less than 50% is typical of symptomatic patients), lung volumes (raised residual volume and total lung capacity, with a gap between plethysmographic and gas dilution volumes because the bulla traps gas), and diffusing capacity (reduced in extensive disease).
• Perfusion scanning or CT angiography to show that the lung around the bulla has good perfusion (suggesting reversible compression). Arterial blood gas, echocardiography for pulmonary hypertension, and CT-guided assessment of fissure integrity when bronchoscopic treatment is considered.
• Alpha-1 antitrypsin level, HIV test, and Xpert MTB/RIF when infection is possible.

• Smoking and cannabis cessation (essential): varenicline 0.5 mg daily for 3 days, 0.5 mg twice daily for 4 days, then 1 mg twice daily for 12 weeks; nicotine patch 21 mg/24 h; behavioural support.
• Medical therapy of the underlying COPD:
  • Long acting muscarinic antagonist and beta agonist (indacaterol/glycopyrronium 110/50 micrograms once daily, or umeclidinium/vilanterol 62.5/25 micrograms once daily), with salbutamol 100 to 200 micrograms as needed; inhaled corticosteroid in frequent exacerbators with eosinophils of 300 per microlitre or more.
  • Pulmonary rehabilitation, vaccination (influenza, pneumococcal conjugate, COVID-19), nutrition, and oxygen if hypoxaemic.
  • Avoid scuba diving, high altitude flights without assessment, and positive pressure ventilation without monitoring for pneumothorax.
• Observation: asymptomatic small bullae and stable giant bullae with preserved function can be watched with chest X-ray or CT every 6 to 12 months.
• Bullectomy (surgical removal of the bulla) for patients with a giant bulla causing breathlessness and compression of relatively healthy adjacent lung:
  • Selection: a bulla occupying more than one third of the hemithorax, progressive symptoms, FEV1 less than 50% predicted and greater than about 35 to 40% predicted, good perfusion of the compressed lung on scan or CT, no severe pulmonary hypertension or hypercapnia (PaCO2 less than 6.7 kPa), stopped smoking, and no extensive diffuse emphysema.
  • Techniques: video assisted thoracoscopic resection with stapling or oversewing and pleural reinforcement, or open thoracotomy for very large bullae, with a parenchyma sparing approach. Results: improvement in FEV1 (increase of 20 to 50%), dyspnoea and exercise tolerance in most; operative mortality about 2 to 5% (higher in poor lung function); benefit lasts about 3 to 5 years and recurrence may follow in the remaining emphysematous lung.
  • Alternatives for high risk patients: bronchoscopic valve placement in the bulla's draining bronchus (evidence is limited), percutaneous catheter drainage (Monaldi technique) or thoracoscopic drainage as palliation, and endobronchial treatment in specialist centres.
• Pneumothorax in bullous disease:
  • Confirm by CT that air is in the pleural space rather than a bulla (an X-ray alone can mislead).
  • Small pneumothorax and minimal symptoms: observe with oxygen and repeat X-ray at 24 hours.
  • Large or symptomatic: intercostal chest drain (small bore 12 to 14 French with underwater seal; avoid trocar insertion in a bulla), with suction at 10 to 20 cmH2O if there is a persistent leak.
  • Persistent air leak beyond 3 to 5 days or recurrence: video assisted thoracoscopic surgery with bullectomy and pleurodesis (mechanical abrasion or talc 4 to 5 g sterile poudrage), or bronchoscopic valve therapy when surgery is not possible; chemical pleurodesis through the drain with talc slurry 4 to 5 g if the patient is unfit for surgery.
  • After a first pneumothorax in bullous disease, definitive treatment is advised because of recurrence risk of about 40 to 50%.
• Infected bulla: antibiotics for 2 to 6 weeks (co-amoxiclav 625 mg orally three times daily, or clindamycin 300 to 450 mg four times daily, with ciprofloxacin or an anti-pseudomonal agent when Pseudomonas is likely), and drainage for a large infected cavity.
• Aspergilloma in a bulla: observe if asymptomatic; for haemoptysis give tranexamic acid 1 g orally or IV every 8 hours (evidence is limited), bronchial artery embolisation for significant bleeding, and surgical resection for recurrent massive haemoptysis in fit patients; itraconazole 200 mg twice daily or voriconazole 4 mg/kg twice daily has limited benefit.
• Lung cancer in or near a bulla: biopsy by CT or bronchoscopy with great care (pneumothorax risk), and specialist oncology and surgical review.
• Special groups:
  • Alpha-1 antitrypsin deficiency: lower lobe disease; consider augmentation therapy (alpha-1 proteinase inhibitor 60 mg/kg IV once weekly) in non-smokers with FEV1 35 to 65% predicted (evidence is limited), and screen the family.
  • Marfan and connective tissue disease: higher pneumothorax recurrence; early definitive pleurodesis.
  • Cannabis users: stop all smoking; young men often do well after bullectomy.
  • Pregnancy: bullae can rupture during labour; avoid prolonged Valsalva, and plan delivery with specialist input.
  • Air travel: avoid after a pneumothorax until resolution is confirmed (usually 2 to 6 weeks) and discuss the risk of giant bullae.
• Red flags: sudden chest pain with breathlessness, tension signs (hypotension, tracheal deviation), haemoptysis, fever with a new air fluid level, rapid enlargement on imaging.
• Follow up: review at 2 to 4 weeks after any procedure and then every 6 to 12 months with spirometry and chest imaging; yearly review of smoking status and symptoms; refer to a thoracic surgical or interventional service for progressive or complicated disease.