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SVC obstruction

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SVC obstruction

Aetiology

  • 78% of cases due to malignancy: lung CA (especially oat cell), lymphoma, breast CA, thymic tumours, testicular CA, mets from unknown primary
  • mediastinal fibrosis (11%)
  • thrombosis
  • inflammatory lymphadenopathy
  • radiation fibrosis
  • idiopathic

Pathophysiology

  • SVC particularly prone to obstruction because of its thin walls, low pressure and the fact that it is surrounded by relatively firm nondistensible neighbouring structures (eg trachea, sternum, right main bronchus)
  • symptoms depend to some extent on speed of progression of obstruction. Slow processes allow time for the development of collaterals while rapidly growing tumours may produce more dramatic symptoms
  • location of block relative to the opening of the azygos vein into the SVC is important in determining clinical features. If the block allows the azygos to function as a bypass system most of the signs and symptoms are in the superepigastric region. If not the collaterals must flow inferiorly to drain into the IVC
  • symptoms are due to poor venous return, increased intravenous pressure, collateral development and underlying disease process

Clinical features

  • orthopnoea common
  • symptoms may be increase in prone position
  • headaches and nightmares which are lessened by sleeping upright. Vertigo, drowsiness, dry eyes or teary eyes. Due to increased cerebral venous pressure
  • change in voice due to laryngeal oedema
  • dysphagia due to oesophageal oedema or invasion
  • syncope occas.
  • visual disturbance
  • swelling of neck and arms
  • prominent venous pattern over chest ± upper abdomen
  • ± chemosis
  • ± "full" supraclavicular fossae

Investigations

  • CXR. Abnormal in 80%. Superior mediastinal mass can be seen in 70% of patients
  • contrast CT allows visualization of collateral system. localizes mass and gives clues to other impending complications
  • investigations to obtain tissue diagnosis

Treatment

  • radiotherapy should produce response in 3-5 days for more sensitive tumours and 7 days for less sensitive
  • chemotherapy has been used successfully on its own for SVC syndrome secondary to oat cell CA but success is limited
  • dexamethasone 4-8 mg 6hrly
  • supportive management

Specific ICU problems

  • airway obstruction
  • loss of consciousness due to cerebral anoxia
  • respiratory arrest due to failure of respiratory centre
  • bleeding

Further reading

Greene HL, Lopez AM. Oncologic emergencies. In Rippe JM, Irwin RS, Fink MP, Cerra FB (eds), Intensive Care Medicine, 3rd ed. Little Brown & Co., Boston, 1996, pp 1437-54


© Charles Gomersall December 1999

 

©Charles Gomersall, April, 2014 unless otherwise stated. The author, editor and The Chinese University of Hong Kong take no responsibility for any adverse event resulting from the use of this webpage.
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