SVC Obstruction DDx

• Obstruction of the superior vena cava results from mediastinal mass lesions.
• Features include a plethoric and cyanosed face with periorbital oedema, exophthalmos, conjunctival injection, and venous dilatation in the fundi, distended non-pulsatile neck veins and a positive Pemberton sign.

Causes

• lung cancer (90%)
• retrosternal tumours e.g. lymphoma, thymoma, dermoid
• retrosternal goitre
• massive mediastinal lymphadenopathy
•  aortic aneurysm

OVERVIEW

• impaired venous return through the SVC to the RA
• SVC = principle venous drainage to head, neck and upper extremities
• major collateral = azygous vein which joins SVC posteriorly over the right main bronchus and drains the posterior thorax.
• if obstruction distal to azygous -> body can cope
• if obstruction proximal to azygous -> flow must bypass the SVC and return via the internal mammary, superficial thoracoabdominal, vertebral venous system -> IVC -> resulting in very high pressures

HISTORY

• SOB
• oedema to face, neck, upper torso, upper limbs
• cough
• hoarseness
• syncope
• headaches
• chest pain
• dysphagia

RISK FACTORS

• bronchogenic carcinoma
• lymphoma
• breast cancer
• other malignancies
• indwelling catheters
• granulomatous disease

EXAMINATION

• JVP distension (non-pulsatile)
• oedema of face or upper extremities
• dilated venous collaterals
• plethora
• tachypnoea
• exopthalmos
• conjunctival injection
• Pemberton’s sign
• papilloedema
• stridor
• Horners syndrome
• cardiac tamponade
• pleural effusions
• hoarse voice
• phrenic nerve paralysis -> high hemidiaphragm

INVESTIGATIONS

• CXR: masses
• HRCT: thoracic neoplasm, retrosternal thyroid, mediastinal fibrosis, thrombosis from intravascular device, aneurysm
• bronchoscopy:
• TTE:
• mediastinoscopy + biopsy
• MRI: masses
• node biopsy
• sputum cytology
• bone marrow aspiration

MANAGEMENT

Goals

(1) diagnose cause
(2) treat obstruction
(3) supportive care

• determined by aetiology
•  early consultation (oncology, radiation oncology, cardiothoracics)
•  steroids
• chemotherapy
• radiotherapy (30 Gr in 10 fractions)
• thrombolytics in thrombotic cases -> stent -> anticoagulation
• surgical resection and reconstruction
• IV access in IVC territory
• prepare for:

-> cardiovascular collapse (tamponade)
-> central airway obstruction
-> laryngeal dysfunction
-> associated respiratory failure

• may respond to adopting the prone position

CCC Differential Diagnosis Series
NEURO	Anosmia, Ataxia, Blepharospasm, Bulbar and Pseudobulbar palsy, Central Pontine Myelinosis, Cerebellar Disease, Chorea, Cranial nerve lesions, Dementia, Dystonia, Exophthalmos, Eye trauma, Facial twitches, Fixed dilated pupil, Horner syndrome, Loss of vision, Meningism, Movement disorders, Optic disc abnormality, Parkinsonism, Peripheral neuropathy, Radiculopathy, Red eye, Retinal Haemorrhage, Seizures, Sudden severe headache, Tremor, Tunnel vision
RESP	Bronchial breath sounds, Bronchiectasis, High airway pressures, Massive haemoptysis, Sore throat, Tracheal displacement
CVS	Atrial Fibrillation, Bradycardia, Cardiac Failure, Chest Pain, Murmurs, Post-resuscitation syndrome, Pulseless Electrical Activity (PEA), Pulsus Paradoxus, Shock, Supraventricular tachycardia (SVT), Tachycardia, VT and VF, SVC Obstruction
GIT	Abdominal distension, Abdominal mass, Abdominal pain, Asterixis, Dysphagia, Hepatomegaly, Hepatosplenomegaly, Large bowel obstruction, Liver palpation abnormalities, Lower GI haemorrhage, Malabsorption, Medical causes of abdominal pain, Rectal mass, Small bowel obstruction, Upper GI Haemorrhage
GUT	Genital ulcers, Groin lump, Scrotal mass, Urine colour, Urine Odour, Urine transparency,
MSK	Arthritis, Shoulder pain, Wasting of the small muscles of the hand
DERM	Palmar erythema, Serious skin signs in sick patients, Thickened Tethered Skin, Leg ulcers, Skin Tumour, Acanthosis Nigricans
ENDO	Diabetes Insipidus, Diffuse Goitre, Gynaecomastia, Hirsutism, Hypoglycaemia, SIADH, Weight Loss
HAEM	Splenomegaly
PAEDS	Floppy infant
MISC	Anaphylaxis, Autoimmune associated diseases, Clubbing, Parotid Swelling, Splinter haemorrhages, Toxic agents and abnormal vitals, Toxicological causes of cardiac arrest
IMAGING	CHEST: Atelectasis, Hilar adenopathy, Hilar enlargement on CXR, Honeycomb lung, Increased interstitial markings, Mediastinal widening on mobile CXR, Pulmonary fibrosis, Pseudoinfiltrates on CXR, Pulmonary opacities on CXR, ABDO: Gas on abdominal X-ray, Kidney mass, BRAIN: Intracranial calcification, Intracranial structures with contrast, Ventriculomegaly, OTHER: Pseudofracture on X-Ray,
LABS	LOW: Anaemia, Hypocalcaemia, hypochloraemia, Hypomagnesaemia,  HIGH: Bilirubin and Jaundice, Hyperammonaemia, Hypercalcaemia, Hyperchloraemia, Hyperkalaemia, Hypermagnesaemia,  ACID BASE: Acid base disorders, Resp. acidosis, Resp. alkalosis, Creatinine, CRP, Dipstick Urinalysis, Laboratory Urinalysis, Liver function tests (LFTs), Pleural fluid analysis, Urea, Urea Creatinine Ratio, Uric acid, Urinalysis, Urine Electrolytes

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