Cardiovascular

Superior vena cava obstruction

Compression, invasion or thrombosis of the superior vena cava blocks venous drainage from the head, neck and arms, raising upstream pressure until collaterals open or the airway is threatened.

In a nutshell

Superior vena cava obstruction (SVCO) is blocked venous drainage from the head, neck and arms, malignant in over 90% of cases. Sit the patient up, give oxygen if needed, obtain urgent CT and involve acute oncology; dexamethasone is an off-label regional option, not a settled national first-line treatment.

Classic presentation

A smoker with a new right upper lobe mass has three days of facial and arm swelling, headache worse on stooping, and fixed, non-pulsatile distended chest-wall veins.

Key points

SVCO occurs in 3 to 8% of people with cancer. Lung cancer causes 65 to 80% and lymphoma 2 to 10%; benign causes are rare.
Slow occlusion lets chest-wall collaterals open, so symptoms stay mild. Rapid occlusion gives dramatic swelling because nothing has had time to compensate.
Yu grade 3 adds headache, dizziness, laryngeal oedema or syncope on bending; grade 4 adds confusion, stridor or haemodynamic compromise.
Two current UK guidelines give the same 16 mg daily total differently: 8 mg twice daily throughout, or 16 mg once daily for two days first.
Dexamethasone here is off-label. The BNF oral range for suppressing inflammatory disorders is 0.5 to 10 mg daily, and no trial shows benefit in SVCO.
Performance status runs 0 (normal activity) to 4 (chair or bed bound). It, and whether the patient can lie flat, decide stenting and radiotherapy.
Enoxaparin treatment dose with cancer is 1 mg/kg subcutaneously every 12 hours. Avoid it if creatinine clearance is below 15 mL/minute.
There is no NICE severity score and no national UK SVCO guideline. NG122 covers only the lung cancer arm.

First-line investigation

Contrast-enhanced venous-phase CT of the thorax, requested urgently and done within 24 hours. Add CT pulmonary angiography (CTPA) if pulmonary embolism is suspected.

Management

Sit up, oxygenate, escalate

Sit the patient upright, support the arms on pillows and loosen tight clothing. Oxygen to saturations 94 to 98%, or 88 to 92% if at risk of hypercapnic respiratory failure.^1,5,9
Do not cannulate or infuse into a swollen arm. Discuss with a registrar or above immediately, and with an oncologist within 24 hours.^5,2,8
Stridor, confusion, syncope or hypotension is Yu grade 4 and life-threatening. Call ear, nose and throat (ENT) and critical care, and escalate for urgent stenting.^5,3,6

Confirm it and grade it

Request contrast-enhanced venous-phase CT of the thorax, to be done within 24 hours. Add CT pulmonary angiography (CTPA) if pulmonary embolism is suspected.^3,2
Send FBC, U&E, LFT and a clotting screen before biopsy, anticoagulation or contrast. A chest radiograph may show a widened mediastinum or hilar mass.^3,5
Grade 1: swelling alone. Grade 2: plus dysphagia, cough or visual disturbance. Grade 3: headache, dizziness, laryngeal oedema or syncope on bending. Grade 4: confusion, stridor, haemodynamic compromise.⁵

Dexamethasone: regional and specialist-led

No national guideline or trial establishes benefit. If the agreed regional pathway selects dexamethasone, one regimen is 8 mg orally twice daily; start before CT only after senior acute-oncology or haematology discussion.²
Scottish palliative guidance gives an alternative regional regimen: dexamethasone 16 mg orally or parenterally immediately and the next day, then 8 mg twice daily. This is off-label practice, not trial-proven care.¹
If a haematological malignancy is suspected and nothing is life-threatening, get senior oncology or haematology advice before the first dose: steroids can impair the histology of lymphoma.^7,3
If dexamethasone is selected, add omeprazole 20 mg orally daily or lansoprazole 30 mg orally daily, monitor capillary glucose at least daily and issue a Steroid Treatment Card.^2,7,10
Stop dexamethasone if the CT shows no obstruction. Consider stopping if there is no improvement by 7 days; reduce gradually over several weeks in responders.^2,1

Open the vein, treat the tumour

Get histology before cancer treatment whenever the patient is stable: node fine-needle aspiration, bronchoscopy or CT-guided biopsy, chosen with respiratory, oncology and radiology.²
NICE: offer chemotherapy and radiotherapy based on stage of disease and performance status, and consider stent insertion for immediate relief of severe symptoms or after earlier treatment fails.⁶
The stent is a wire mesh tube 6 to 10 cm long placed by an interventional radiologist. Ask whether the patient can lie reasonably flat.^11,2

Thrombus, lines and leads

When CT shows thrombus, weigh bleeding and biopsy risks before anticoagulation, and establish whether any central venous catheter or pacemaker lead remains necessary.^2,5
Enoxaparin treatment dose with cancer is 1 mg/kg subcutaneously every 12 hours. Avoid if creatinine clearance is below 15 mL/minute; reduce it if 15 to 30 mL/minute.¹²
If a proximal deep vein thrombosis or pulmonary embolism is also confirmed, NICE advises 3 to 6 months of anticoagulation and considering a direct-acting oral anticoagulant (DOAC).¹³

Symptom control

For distressing breathlessness in an opioid-naive adult the BNF starting dose is immediate-release oral morphine 500 micrograms every 12 hours, titrated upwards. Benzodiazepines and oxygen also help.^14,1

Reassess

Review swelling, breathing and conscious level daily, and the steroid response at 7 days. After stenting watch for thrombosis, migration, arrhythmia and new pulmonary oedema.^2,11

Exam traps

The distended veins of SVCO are fixed and non-pulsatile. A pulsatile jugular venous pressure points to a cardiac cause instead.
Steroids can destroy the histology of lymphoma. If lymphoma is suspected and nothing is life-threatening, ask haematology before the first dose.
Do not cannulate or infuse into the swollen arm: the fluid drains straight into the obstructed territory.
Do not treat pre-CT dexamethasone as automatic: it is an off-label regional practice requiring senior acute-oncology or haematology agreement. If selected, stop it if CT shows no obstruction.
Stenting relieves the vein but treats no cancer. NICE positions it for immediate relief of severe symptoms or after earlier treatment fails, not as routine first-line.
Restoring venous return after stenting can precipitate heart failure and pulmonary oedema. It is recognised and occasionally fatal.
A generic SVCO label is not a treatment plan. Small-cell lung cancer, lymphoma and germ-cell tumours all need different drugs.

Illustrations

Morning facial swelling in SVC obstructionPaired clinical photographs showing facial swelling and venous congestion in superior vena cava obstruction. The appearance should trigger urgent assessment but cannot identify the cause.Herbert L. Fred, MD and Hendrik A. van Dijk, Wikimedia Commons · Attribution

SVC obstruction on contrast CTAn axial contrast-enhanced CT of the chest showing obstruction of the superior vena cava with a mediastinal process and venous collaterals.James Heilman, MD, Wikimedia Commons · CC-BY-SA-3.0

Key sources

This page is exam revision material, not medical advice, and must not be used for patient care. Always check drug doses against the BNF and current guidance. Full disclaimer.