Study note
MedicineCardiology

Acute limb ischaemia: recognition and urgent management

THE CONTEXT
Acute limb ischaemia can rapidly threaten limb viability. Its cause influences treatment and prognosis, making immediate vascular surgical discussion essential.

Causes and clinical assessment

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Frequent causes are acute thrombotic occlusion of a pre-existing stenotic arterial segment, thromboembolism and trauma, including iatrogenic trauma.
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Typical findings include paralysis, demonstrated by inability to wiggle toes or fingers, and paraesthesia, described as loss of light touch over the dorsum of the foot or hand.
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The usual clinical features are non-specific and inconsistently related to severity. Pain on squeezing the calf indicates muscle infarction and impending irreversible ischaemia.

Immediate action

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Every suspected acutely ischaemic limb requires immediate discussion with a vascular surgeon; a few hours may determine whether complete recovery, amputation or death occurs.
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If there are no contraindications, administer an intravenous heparin bolus of 3000–5000 U to limit thrombus propagation and protect collateral circulation.
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Contraindications listed are acute aortic dissection and trauma, particularly head injury.

Treatment according to cause and viability

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Distinguishing thrombosis from embolism is often difficult but matters because treatment and prognosis differ.
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Thrombosis in situ can usually receive initial medical treatment with intravenous heparin targeting an activated partial thromboplastin time of 2.0–3.0, antiplatelet agents, high-dose statins, intravenous fluids to avoid dehydration, correction of anaemia, oxygen and sometimes prostaglandins such as iloprost.
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Embolism normally causes extensive tissue necrosis within 6 hours unless revascularisation occurs.
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The indications for thrombolysis remain controversial. Irreversible ischaemia requires early amputation or palliative care.
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