Acute Limb Ischaemia

Acute limb ischaemia is when there's a sudden decrease in perfusion to a limb, immediately threatening it. It can either be caused by Thrombosis or an Embolism.

Thrombosis - Presents less acutely with less dramatic symptoms, and often in those with a history of claudication.

Embolism - Presents much more acutely (over mins) with very dramatic symptoms, and often in those with a history of embolic sources (e.g. AF).

Presentation

6 P’s:

• Pulseless

• Pain

• Pale

• Perishingly cold

• Paraesthesia

• Paralysis

N.B. In real life, loss of motor and sensory function are signs of an unsalvageable limb!

Investigations and Management

Investigations to do include:

• Bloods - FBC, U&E, G&S, Clotting

• ECG - AF suggests an embolic cause

• CT Angiogram

N.B. If embolic, it tends to cause multiple acute occlusions.

Management if thrombotic:

• If incomplete, the limb is likely to remain viable for 12-24 hours, so patients should have angiography before endovascular procedure is done (e.g. angioplasty, thrombectomy)

• If complete, patient is for urgent bypass surgery as imaging will delay management

Management if embolic - Leg is typically threatened, so patient is for immediate embolectomy

Long-term risk management:

• Antiplatelet therapy i.e. Aspirin/Clopidogrel 75mg

• Statin therapy

• Lifestyle - Smoking cessation, diet, exercise

• Risk factor control e.g. DM, HTN

Complications

The main complication to be aware of after re-vascularising an ischaemic leg is reperfusion injury! This causes:

• Oedema → Compartment syndrome

  • Fasciotomy will have to be done, which comes with its own associated risks and complications e.g. nerve damage

• The release of substances that have built up in the tissue:

  • Hyperkalaemia → arrhythmias

  • Release of H+ ions → Acidosis

  • Release of myoglobin → Acute kidney injury (myoglobin causes acute tubular necrosis)