AKT · Cardiovascular/Vessels, aorta & venous

Acute limb ischaemia

Sudden arterial occlusion (embolus, in-situ thrombosis, graft occlusion) → limb-threatening ischaemia

Overview

Sudden loss of arterial perfusion threatening limb viability, usually from an embolus (often AF) or acute thrombosis of a diseased artery. It is a surgical emergency recognised by the 6 Ps; time to revascularisation determines limb salvage, and reperfusion brings its own risks (compartment syndrome, hyperkalaemia).

Recognise

The 6 Ps: Pain, Pallor, Pulselessness, Perishingly cold (Poikilothermia), Paraesthesia, Paralysis
Embolic (AF, mural thrombus) → sudden, in a limb with otherwise normal pulses; thrombotic → on a background of claudication/PAD
Fixed mottling, paralysis and a tense, tender muscle indicate advanced, possibly non-viable, ischaemia

Red flags

Paralysis, fixed mottling or muscle tenderness = threatened/non-viable limb → emergency revascularisation or primary amputation
After reperfusion: compartment syndrome (fasciotomy) and reperfusion injury (hyperkalaemia, AKI)

Differentials & how to tell them apart

Critical limb ischaemia (chronic)gradual, with claudication history and chronic skin changes

Deep vein thrombosisswollen, warm, with pulses present

Acute compartment syndromepain out of proportion, tense compartments — can also follow reperfusion

Investigations

Clinical diagnosis — do not delay; handheld Doppler of pulses; urgent CT angiography if it won't delay treatment in a viable limb; ECG (AF as embolic source); bloods incl. K, lactate, creatine kinase, group & save.

Management

IV heparin immediately + urgent revascularisation (embolectomy/thrombectomy/thrombolysis)

1Recognise the 6 Ps and give IV heparin and analgesia at once; assess viability with Doppler. Find the source (AF/embolus vs thrombosis on chronic disease).Gate: A viable/threatened limb → urgent revascularisation; a non-viable limb (paralysis + fixed mottling + anaesthesia) → primary amputation, not revascularisation.
2Revascularise (embolectomy, thrombectomy or thrombolysis); watch for and treat compartment syndrome (fasciotomy) and reperfusion hyperkalaemia/AKI; anticoagulate and treat the embolic source.

Immediate IV heparin + analgesia + oxygen — limit clot propagation while arranging definitive treatment

Urgent revascularisation: embolectomy, surgical/endovascular thrombectomy or thrombolysis — time-critical for limb salvage; choice depends on cause and viability

Fasciotomy for compartment syndrome; treat reperfusion hyperkalaemia — after restoring flow

Primary amputation — for a non-viable limb (fixed mottling, paralysis, anaesthesia)

Key points

Sudden painful, pale, pulseless, cold, paraesthetic, paralysed limb (6 Ps) = acute limb ischaemia → IV heparin immediately and urgent revascularisation. Paralysis + fixed mottling = non-viable → amputation. After reperfusion, watch for compartment syndrome and hyperkalaemia. Look for AF.

Monitor & prognosis

Limb perfusion post-revascularisation, compartments, K/CK/renal function, anticoagulation.

Limb salvage depends on time to revascularisation; advanced ischaemia risks amputation/death.

Source: Vascular Society; cross-ref acute_care