Acute limb ischaemia (ALI) is a severe, symptomatic hypoperfusion of a limb that has been occurring for less than 2 weeks; although the definition specifies a 2-week period, this condition is considered a surgical emergency and demands urgent intervention, ideally within 4-6 hours

Aetiology

• Thrombosis (40%) - this often results from the rupture of atherosclerotic plaques
• Embolism (40%) - these are most commonly observed in patients with atrial fibrillation.
• Vasospasm - such as observed in Raynaud's phenomenon
• External vascular compromise: trauma, compartment syndrome

Clinical features

• The signs and symptoms of ALI are represented by the mnemonic "6Ps":
  • Pulseless
  • Painful
  • Pale
  • Paralysis
  • Paraesthesia
  • Perishingly cold
• Acute limb ischaemia secondary to thrombosis typically has a sub-acute onset and is associated with features of peripheral vascular disease in the contralateral limb
• In contrast, ALI secondary to embolisation has a more acute onset and often results from atrial fibrillation

Investigations

• Initial investigations should include:
  • Bloods: FBC, U&Es, blood grouping and saving, clotting profileE
  • ECG: particularly useful to detect atrial fibrillation, suggesting an embolic cause for ALI
• The patient should be referred immediately to vascular surgery for further management

Management

• The management of acute limb ischaemia varies based on the cause of the condition
• For thrombotic causes, management strategies include:
  • Angiography for incomplete ischaemia: this helps map the occlusion site and plan for intervention
  • Potential endovascular procedures include angioplasty, thrombectomy, or intra-arterial thrombolysis
  • Urgent bypass surgery for complete ischaemia
• For embolic causes, the leg is typically threatened, and immediate embolectomy is required
  • If embolectomy fails, on-table thrombolysis may be considered
• In cases where the limb is non-viable, amputation may be required
• In all cases, the patient should be kept nil by mouth in preparation for potential surgical interventions
• Intravenous heparin may be administered to prevent further thrombus propagation, typically after a senior review