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Acute limb ischaemia

Acute limb ischaemia is a sudden decrease in limb perfusion that causes a time-critical threat to limb viability. Patients who present with two weeks of symptoms of ischaemia are considered to have chronic limb ischaemia (manifested by ischaemic rest pain, ischaemic ulcers and/or gangrene). This pathway deals with acute limb ischaemia.

Acute limb ischaemia may be due to thrombosis, embolism, or rarely dissection. Risk factors

  • Atrial fibrillation

  • Recent myocardial infarction

  • Aortic atherosclerosis

  • Large vessel aneurysmal disease (eg, aortic aneurysm, popliteal aneurysm)

  • Prior lower extremity revascularization (angioplasty/stent, bypass graft)

  • Risk factors for aortic dissection

  • Arterial trauma

  • Deep vein thrombosis (paradoxical embolism or phlegmesia)

Step 1: Pathway Entry

Patients with acute arterial occlusion usually present with some of the 6 ‘Ps’: pain, pallor, pulselessness, perishingly cold, paraesthesia and paralysis. Paraesthesia and paralysis from ischaemia indicate a threatened limb that requires emergency surgical review, regardless of the cause.

Step 2: Is the Patient Stable?

Resuscitate if unstable. Damage from an acutely ischaemic limb is exacerbated by hypotension and hypoxia.

Step 3: Focused assessment

Obtain a focused history and examination. In particular, look for symptoms of peripheral arterial disease prior to the onset of the acute limb ischaemia, the presence of atherosclerotic risk factors, which suggest pre-existing thrombosis. Bedside doppler is useful to assess and detect peripheral pulses.

Peripheral pulses should be examined and documented. The intensity is graded 0 to 4+:

  • 0 no palpable pulse;
  • 1+ a faint, but detectable pulse;
  • 2+ diminished pulse;
  • 3+ normal pulse; and
  • 4+ a bounding pulse.

Bruits (detected by auscultation over the large and medium-sized arteries e.g., carotid, brachial, abdominal aorta, femoral, with the diaphragm of the stethoscope using light to moderate pressure) and the presence of a "thrill" (palpable vibratory sensation over a vessel in which a loud bruit is audible, indicative of marked turbulence in local blood flow suggesting significant vascular pathology) should be noted.

12 lead ECG to look for atrial fibrillation (possible embolic source). Send bloods for FBC, EUC, CK, coagulation, lactate (may be helpful in assessing and tracking the degree of tissue hypoperfusion) and G+S if surgery imminent or possible.

Step 4: Is the Limb Viable?

  • Viable

    • Not immediately threatened

    • No sensory loss or weakness

    • Audible arterial doppler signals

    • Urgent work up indicated

  • Marginally threatened

    • Salvageable if promptly treated

    • Minimal sensory loss (toes or none), no weakness

    • Often inaudible arterial doppler

  • Immediately threatened

    • Salvageable with immediate revascularisation

    • Sensory loss affecting more than the toes or distal fingers with rest pain

    • Mild to moderate weakness

    • Usually inaudible arterial Doppler

    • Emergency intervention indicated

  • Irreversible

    • Major tissue loss and permanent nerve damage inevitable

    • Profound sensory loss

    • Paralysis

    • Inaudible arterial Doppler

    • Amputation indicated

Step 5: Diagnosis

Further imaging would be after consultation with the vascular surgeon, and is determined by viability of the limb and availability of imaging modalities. Options include

  • Duplex ultrasonography

  • CT angiography

  • Angiography in OT

Step 6: Management

Early consultation of vascular surgeon will guide treatment. In the ED treatment would include

  • Correction of dehydration with IV fluids

  • Keeping the patient NBM in anticipation of further intervention

  • Analgesia

  • IV heparin

Definitive treatment would depend on the viability if the limb, aetiology and location of the lesion, surgical preference and patient suitability for surgery. Peripheral occlusions in a viable limb may be managed by catheter directed thrombolysis, whereas revascularisation of the threatened limb is more time critical. Irreversible changes may occur with 4-6 hours of ischaemia. Surgical options include:

  • Embolectomy (catheter or open)

  • Bypass (if arterial thrombosis present)

Treatment of the non-viable limb is amputation.

Further references and resources