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Acute limb ischaemia
Acute limb ischaemia threatens the limb within hours; heparin is given at once, the limb is graded by Rutherford — sensory loss and weakness demand urgent revascularisation — and after revascularisation compartment syndrome is sought.
Why it matters in the exam
The classic case is a patient with atrial fibrillation who arrives with a suddenly cold, pale and painful leg — an embolism; by contrast, a patient with a history of intermittent claudication and weak pulses in the other leg develops thrombosis on atherosclerosis. Questions test the "six Ps" (pain, pallor, pulselessness, paraesthesia, paralysis and poikilothermia), and above all the importance of sensation and movement: sensory loss beyond the toes and muscle weakness mean the limb is "immediately threatened", so any unnecessary delay for work-up endangers it.
The second part is treatment: an intravenous bolus of unfractionated heparin as soon as the diagnosis is made, rapid imaging (CT angiography) when it does not delay care, and revascularisation — Fogarty catheter embolectomy for an embolism, and bypass, endovascular treatment or catheter-directed thrombolysis for thrombosis. A limb with complete paralysis, muscle rigidity and absent sensation is not salvageable, and the treatment is amputation. After revascularisation, reperfusion injury, compartment syndrome (fasciotomy), hyperkalaemia and myoglobinuria are expected.
Key points
- The six Ps: pain, pallor, pulselessness, paraesthesia, paralysis, poikilothermia.
- Heparin at once at diagnosis.
- Sensory loss beyond the toes or weakness (IIb) — immediate revascularisation.
- Paralysis and rigidity (III) — amputation.
- After revascularisation — compartment syndrome, potassium and CK.
Summary table
| Rutherford class | Findings | Treatment |
|---|---|---|
| I — viable | No sensory loss, no weakness; audible arterial Doppler signal | Heparin and relatively urgent revascularisation |
| IIa — marginally threatened | Minimal sensory loss in the toes, no weakness | Heparin and prompt revascularisation (surgery, endovascular or thrombolysis) |
| IIb — immediately threatened | Sensory loss beyond the toes, rest pain, mild to moderate weakness | Heparin and immediate revascularisation, usually surgical |
| III — irreversible | Absent sensation, paralysis, muscle rigidity | Amputation |
| After revascularisation | Severe pain, swollen tense limb | Fasciotomy; monitor potassium, CK and renal function |
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Sources
- ESVS Clinical Practice Guidelines on the Management of Acute Limb Ischaemia, 2020 — Classification, heparin, revascularisation and fasciotomy
- ACC/AHA/multisociety Guideline for the Management of Lower Extremity Peripheral Artery Disease, 2024 — Acute limb ischaemia
- Sabiston Textbook of Surgery, 21st edition (2022) — Peripheral Arterial Occlusive Disease
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-02. The text may contain errors; when in doubt, check the source.