Acute limb ischemia
Acute limb ischemia is a sudden decrease in limb perfusion threatening viability, usually from arterial embolism (often cardiac) or in situ thrombosis. It presents with the six Ps and is a time-critical emergency: immediate anticoagulation with heparin and urgent revascularization determine limb salvage, guided by the Rutherford category.
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What this article covers
- Overview
Definition: acute limb ischemia is a sudden (less than two weeks) decrease in arterial perfusion of a limb that threatens its viability.
- Epidemiology
Caused by embolism or in situ thrombosis, in roughly comparable proportions.
- Risk factors
Atrial fibrillation and other cardiac sources of embolism (mural thrombus, valve disease).
- Pathophysiology
Abrupt arterial occlusion: embolism or thrombosis suddenly halts flow, and unlike chronic disease there are few collaterals to compensate.
- Clinical features
The six Ps: pain, pallor, pulselessness, paresthesia, poikilothermia (cold), and paralysis.
- Differential diagnosis
Deep vein thrombosis (phlegmasia cerulea dolens): a swollen, warm, sometimes cyanotic limb, distinguished by preserved arterial pulses and a patent artery on Doppler rather than pulselessness.
- Diagnosis
Establish clinically as a threatened limb and stage by the Rutherford category, with prompt imaging that does not delay treatment: the diagnostic basis is the clinical picture of acute ischemia with…
- Management
First-line, anticoagulate immediately and stage the limb: give intravenous unfractionated heparin at once (an 80 units/kg bolus then an 18 units/kg/hr infusion titrated to aPTT), and provide…
- Complications
Limb loss and amputation. Reperfusion injury: compartment syndrome, hyperkalemia, and acute kidney injury from rhabdomyolysis.
- Prognosis
Highly time-dependent; salvage falls sharply after about 6 hours of ischemia.
- Prevention
Anticoagulation for atrial fibrillation and cardiac embolic sources when the CHA2DS2-VASc score is 2 or higher (warfarin at an INR of 2 to 3, or a DOAC).
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