Acute Limb Ischaemia Flashcards
How can acute limb ischaemia occur and what is its definition?
Most commonly a thrombotic occulusion of a diseased vessel but can be an embolus from a distant site e.g. AF
It is a previously stable limb that has deteriorated in less than 2 weeks
How quickly must an acute ischaemic limb be revascularised before necrosis occurs?
4-6 hours
What is the difference between critical limb ischaemia and acute limb ischaemia?
Acute is over 2 weeks whereas critical is a chronic process
Critical limb ischaemia is ABPI <0.5
ABPI 0.5-0.9 = Peripheral artery disease
What are the three causes of acute limb ischaemia and the associated risk factors?
Emboli - usually cardiac e.g. AF or mural thrombus post MI
Trauma - causing compartment syndrome or direct compression or dissection of artery - most commonly supracondylar humerus fractures or posterior knee dislocations
What are the signs of an acutely ischaemic limb?
Pale Pulseless Paralysis Parasthesia Perishingly cold Painful
How do you initially assess a patient with an acutely ischaemic limb what are your bedside investigations?
Use a-e, keep patient NBM and call for a senior assessment urgently
-Give 15L high flow oxygen through non rebreathe
Get IV access and take bloods from cannula:
-ABG to look at lactate
-FBC - anaemia can worsen ischaemia
-U+E- can have rhabdomyolysis or renal artery stenosis
-Clotting and ground and save - likely going for surgery
-LFTs as baseline
-Glucose and lipids for CVD risk factors
-ESR to assess connective tissue disorders
-ECG to look for AF
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What further investigations are required for an acutely ischaemic limb?
- Handheld doppler can be used for any residual flow to the limb
- Duplex US can be used to determine the severity of the limb ischaemia
- -If patient stable enough Intra arterial digital subtraction angiography is the gold standard (DSA)
What is the management of patients with acute limb ischaemia?
All patients should be heparinised to prevent further spread of the clot - 5000IU unfractionated heparin as a bolus, then 1000IU/hr IV infusion
Tissue viabilitiy should be assessed by a senior collegue to determine management
Fixed mottling of skin implies irreversibility
Surgical options include:
-Embolectomy
-Local catheter directed thrombolysis, angioplasty with or without stenting or bypass
-Trauma repair
What happens if the limb is revascularised after 6 hours?
Can get a reperfusion injury and may require ITU admission for haemofiltration
What are the characteristics of venous leg ulcers?
Typically around gaiter region
Painless
Shallower than arterial
Managed with 4 layer compression banding
What are the features of venous insufficiency?
Oedema, brown pigmentation, lipodermatosclerosis and eczema
What are the features of arterial ulcers?
Occur at pressure points More punched out Painful Cold Low ABPI
What classification score is used for claudication symptom severity?
Fontaine classification
What are the findings for chronic limb ischaemia on examination?
Pallor of the skin, reduced capillary refill, absent/weak peripheral pulses, reduced temperature
- Trophic changes e.g. hair loss, haemosiderin pigmentation, dry and brittle skin, onychomycosis
- Arterial ulcers: small, regular (punched-out appearance), deep, painful, and on pressure points
- Positive Buerger’s test
- Reduced ABPI
- 0.9 – 0.7: Mild ischaemia (claudication pain)
- 0.6 – 0.5: Moderate ischaemia (rest pain)
- <0.5: Critical ischaemia (impending gangrene)
What is the management of patients with peripheral arterial disease?
Conservative: -Smoking cessation, exercise, diet Medical: -Statins -Antihypertensives -Diabetes management
