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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
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