Acute Limb Ischaemia (ALI)

A rapid decrease in limb perfusion, often due to an arterial occlusion, which threatens limb viability. It requires urgent diagnosis and treatment to prevent limb loss.

• Thrombosis: In situ thrombosis often occurs in a limb with pre-existing peripheral arterial disease.
• Embolism: A common cause, usually from cardiac sources like atrial fibrillation or post-myocardial infarction.
• Trauma: Direct trauma to the vessels or compartment syndrome can also lead to ischaemia.

• Pain: Sudden onset, severe and persistent limb pain.
• Pallor: The affected limb appears pale.
• Pulselessness: Absent or reduced pulses distal to the occlusion.
• Paraesthesia: Tingling or ‘pins and needles’ sensation due to nerve ischaemia.
• Paralysis: Muscle weakness or paralysis indicates advanced ischaemia.
• Poikilothermia: The limb feels cooler on palpation due to the lack of blood flow.

• Clinical assessment: Immediate assessment of the ‘6 Ps’ is crucial.
• Doppler ultrasound: To assess blood flow and differentiate between arterial and venous issues.
• CT angiography/MRA: Provides detailed images of the vasculature and location of occlusion.
• Blood tests: May include full blood count, coagulation profile, and lactate levels (indicates tissue ischaemia).

• Resuscitation: Address Airway, Breathing, Circulation. Start IV fluids, pain management, and anticoagulation (usually heparin).
• Revascularisation: Urgent surgical or endovascular intervention is typically required.

  • Catheter-directed thrombolysis: Administering thrombolytics directly to the clot.
  • Surgical Embolectomy: Removal of the embolus if thrombolysis is contraindicated or unsuccessful.
  • Bypass Surgery: Creating a new route for blood flow around the blocked artery.

• Amputation: As a last resort if revascularisation fails or the limb is non-viable.

• Compartment syndrome: Increased pressure within muscle compartments leading to further ischaemia.
• Rhabdomyolysis: Muscle breakdown releasing myoglobin, which can cause kidney damage.
• Reperfusion injury: Can occur after blood flow is restored, leading to tissue damage.

• The prognosis depends on the speed of diagnosis and revascularisation. Early treatment can lead to good outcomes.
• Delayed treatment can result in permanent disability or amputation.

Managing risk factors such as atrial fibrillation, monitoring for heart diseases, and managing peripheral arterial disease can help prevent ALI.

• ALI is a vascular emergency that requires a high index of suspicion and prompt intervention to salvage the affected limb.
• It encompasses a broad differential diagnosis and necessitates a structured approach to management, with the aim of rapid revascularisation to restore perfusion and prevent irreversible damage.