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Pleural Disease – spontaneous pneumothorax, empyema, tumours

1. SPONTANEOUS PNEUMOTHORAX

  • Pneumothorax – accumulation of air in the pleural space leading to pulmonary collapse

Etiology

  • Most common in young adult males
  • Primary – occurs in the absence of lung disease
    • Risk factors – male sex, smoking, family history
  • Secondary – occurs in the setting of lung diseases
    • COPD, asthma, TB, interstitial lung disease, bronchial carcinoma, lack
    • Connective tissue diseases – rheumatoid arthritis, Marfan’s syndrome, systemic sclerosis

Pathophysiology

  • Normally, pressure in pleural space is negative
  • Communication between either alveoli and the pleural space or between outside of thoracic cavity and pleural space results in air continuing to enter the pleural space
    • There is increase in pleural pressure – results in hyperexpanded hemithorax and collapsed lung
  • Further increase in pressure can lead to tension pneumothorax – medical emergency
    • When pleural cavity pressure exceeds atmospheric pressure – leads to lung collapse and tracheal deviation

Clinical features

  • Primary – mild chest pain and breathlessness (patients may wait several days before seeking medical advice)
  • Secondary – symptoms are more severe as the lungs are already diseased
    • Cyanosis (hypoxemia), confusion/headache (hypercapnia)
    • Mnemonic – PTHORAX
      • Pleuritic chest pain, Tracheal deviation, Hyper-resonant, Onset (sudden), Reduced breath sounds unilaterally, Absent fremitus, X-ray (lung collapse)

Investigations

  • Chest XR
    • Visible edge of pleura (sharp white line) – absence of lung markings peripheral to the edge
    • Lung collapse
    • Mediastinal shift – indicates a tension pneumothorax
  • Ultrasound
  • CT

Treatment

  • A small pneumothorax usually resolves without treatment
  • Large pneumothorax (>2cm) – chest tube between 4th and 5th intercostal space mid-axillary line to remove air
  • Tension pneumothorax – urgent needle decompression with large bore needle in 2nd intercostal space mid clavicular line, followed by chest tube placement under water seal
  • Pleurodesis – medical procedure in which part of the pleural space is artificially obliterated

2. PLEURAL EMPYEMA

  • Accumulation of pus in the pleural cavity

Etiology

  • Thoracic sepsis – pulmonary infection, mediastinitis, osteomyelitis
  • Extrathoracic sepsis – subphrenic abscess, hepatic abscess
  • Trauma
    • Iatrogenic – lung resection, oesophageal tears, paracentesis, liver biopsy
    • Non iatrogenic – stabbing, gunshot wounds
  • Organisms
    • Gram positive – S.pneumoniae, Staph
    • G negative – Klebsiella, Enterboacter, E.coli, Pseudomonas
    • Anaerobes – Bacteroides fragilis, fusobacterium

Pathophysiology

  • Acute (exudative) stage – 7 days
    • Infection → edematous pleural membranes → produce proteinaceous fluid
    • Pleura fills with thin serous fluid – low white cell count (WCC)
    • Visceral pleura and underlying lung are mobile
  • Transitional (fibropurulent) stage – 7-21 days
    • Thick opaque fluid with pus and deposition of thin fibrin layer over pleura
    • Empyema fluid – thicker, turbid and higher WCC
    • Lung movement is restricted
  • Vascularisation stage
    • Fibrinous layers organise as collagen and there is increased capillary growth
  • Chronic (organising) stage – >21 days
    • Empyema surrounded by cortex – contains frank pus
    • Compresses underlying lung
    • Draws ribs together – leading to chest deformity and calcification

Clinical features

  • Fever, cough, mucus
  • Pleuritic chest pain, signs of pleural effusion
  • Finger clubbing, dyspnea
  • Fatigue, weight loss

Complications

  • Rupture into lung – bronchopleural fistula
  • Septicaemia and shock

Investigations

  • CXR – fibrosis around empyema cavity
  • US – pockets of fluid
  • Thoracentesis
  • Pus culture

Treatment

  • Treat infection and drain purulent effusion
  • Re-expand lung to fill pleural space
  • Thoracentesis, chest tube, pleural lavage (isotonic saline)
  • Antibiotics (IV and local)
  • Fibrinolytics – intrapleural streptokinase
  • VATS – video assisted thoracoscopic surgery
  • Eloesser flap – rib resected and the skin covering it is sewn to the parietal pleura to permit passive drainage

3. METASTATIC PLEURAL TUMOURS

  • Metastases to the pleura is more common than a primary pleural malignancy (malignant mesothelioma)

Etiology

  • Adenocarcinoma is most likely to metastasise in the pleura
  • Most common primary sites – lung cancer, breast cancer, ovarian cancer, lymphoma

Pathology

  • Metastases effect the visceral and parietal pleura
  • Pleural effusion occurs due to impaired lymphatic drainage and increased capillary permeability

Clinical features

  • Pleural effusion – first manifestation
  • Anorexia, weight loss
  • Dyspnea

Investigations

  • CXR – pleural thickening, effusion, rib destruction
  • CT – enlarged mediastinal lymph nodes, rib lesions

Treatment

  • Manage primary cancer
  • Management of malignant pleural effusion
    • Thoracocentesis
    • Drainage
    • Pleurodesis
    • Thoracoscopy
    • Pleurectomy
    • Indwelling pleural catheter
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