mediastinitis

see also:

• the adult patient with chest pain in the ED

• mediastinum is the extrapleural subdivision of the thorax located between the pleural cavities
• non-suppurative mediastinitis is generally self-limiting reactive condition in association with pneumonia and pleurisy
• suppurative acute mediastinitis is a severe life threatening bacterial infection of the mediastinum
• chronic or sclerosing mediastinitis or mediastinal fibrosis:
  • slowly progressive rare condition
  • may be caused by tuberculosis (TB), histoplasmosis, sarcoidosis, silicosis, fungal infections perhaps via delayed hypersensitivity
  • progressive entrapment of the pulmonary veins, superior vena cava, pulmonary arteries, aorta, portion of tracheobronchial tree, phrenic or recurrent laryngeal nerve and oesophagus either alone or in various combinations may take place over many years.
  • superior vena cava syndrome may also be caused by infiltrative neoplasms of the mediastinum

• perforation of the oesophagus
  • oesophageal fistulae and aorto-oesophageal fistulae
  • Boorhaave's syndrome
  • oesophageal foreign body
  • penetrating trauma
  • pressure necrosis from intercostal drain tubes
• penetrating trauma to mediastinum
• post-operative thoracic surgery eg sternotomy
• descending mediastinitis from head and neck:
  • often due to mixed odontogenic bacterial flora ¹⁾
  • via 3 pathways:
    • retropharyngeal space
    • pre-tracheal space
      • tracheal perforation eg. post-intubation upper airway necrosis
      • infected surgical wounds
    • visceral space which contains the trachea, oesophagus, vagus and recurrent laryngeal nerves, thyroid and parathyroid glands
      • thyroid or laryngeal surgery
• ascending mediastinitis from subphrenic or retroperitoneal infections
  • pancreatitis
  • other infections

• may follow an inciting event (see aetiology)
• symptoms:
  • 80% have dysphagia
  • over 50% have retrosternal pain radiating to interscapular region or the throat
  • 50% have nausea and vomiting
  • 40% have fever and chills
  • 20% have SOB
  • 15% have confusion
• usual signs:
  • tachypnoea
  • tachycardia
  • facial / neck oedema
  • subcutaneous emphysema
  • Hamman’s sign with crunching sounds on auscultation of the heart
• investigations:
  • inflammatory markers usually raised
  • blood cultures should be sent
  • CXR: subcutaneous or mediastinal emphysema, tracheal deviation or pleural effusions may be present
  • CT chest is usually diagnostic +/- small amount of oral contrast
  • MRI may be an alternative in children
• general Mx²⁾:
  • supportive care
  • IV proton pump inhibitors (PPIs)
  • IV antibiotics
  • endoscopic stent for large thoracic level oesophageal perforations or small abdominal perforations
  • large cervical or abdominal oesophageal perforations generally need surgical repair
  • surgical drainage may be an option for some

• one point for each of:
  • Age >75 years
  • Tachycardia
  • Leukocytosis
  • Pleural effusions
• two points for each of:
  • Fever
  • Non-contained leak on barium oesophagram
  • Respiratory compromise
  • Time to diagnosis >24 h
• three points for each of:
  • Presence of malignancy
  • Hypotension
• mortality rates:
  • score < 2 = 2%
  • score 3 or 4 = 6%
  • score of 5 to 7= 26%
  • score of 8 to 10 = 85%
  • score > 10 = 100%