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 2 weeks of ischaemic symptoms are considered to have chronic limb ischaemia. This is 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, e.g. aortic aneurysm, popliteal aneurysm
• Prior lower extremity revascularisation, e.g. angioplasty or stent, bypass graft
• Risk factors for aortic dissection
• Arterial trauma
• Deep vein thrombosis, e.g. paradoxical embolism or phlegmesia
• Smoking
• Hypertension, hypercholesterolaemia
• Diabetes

Assessment and management

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 urgent escalation and emergency surgical review, regardless of the cause.

Step 2: Assess and stabilise the patient

Patients who are unstable require immediate resuscitation, with correction of hypotension and hypoxia, as these factors exacerbate ischaemic limb damage. Move to an area most appropriate for resuscitation and consider urgent CT angiogram if available, once patient has stabilised.

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 as follows:

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

Note bruits and the presence of a ‘thrill’. Bruits are detected by auscultation over the large and medium-sized arteries, e.g. carotid, brachial, abdominal aorta and femoral, with the diaphragm of the stethoscope using light to moderate pressure. A thrill is a 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.

Use a 12 lead ECG to look for atrial fibrillation, as a possible embolic source.

Send bloods for the following:

• Full blood count
• Urea electrolytes creatinine
• Creatine kinase
• Coagulation
• Lactate, which may be helpful in assessing and tracking the degree of tissue hypoperfusion
• G+S if surgery imminent or possible

Step 4: Limb viability

Viable (stage 1)

• Not immediately threatened
• No sensory loss or weakness
• Audible arterial Doppler signals
• Urgent work-up indicated

Marginally threatened (stage 2)

• Salvageable if promptly treated
• Minimal sensory loss, e.g. toes or none; no weakness
• Often inaudible arterial Doppler

Immediately threatened (stage 3)

• 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 (stage 4)

• Major tissue loss and permanent nerve damage inevitable
• Profound sensory loss
• Paralysis
• Inaudible arterial Doppler
• Amputation indicated

Step 5: Diagnosis

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

Imaging options

• Digital subtraction angiography
• CT angiography
• Duplex ultrasonography
• Angiography in operating theatre

Step 6: Management

Early consultation with the vascular surgeon will guide treatment.

Treatment in the ED

• Early escalation to senior medical officer and consultation with the vascular surgeon
• Correction of dehydration with IV fluids
• Keeping the patient nil-by-mouth in anticipation of further intervention
• Analgesia
• IV heparin bolus and infusion. Refer to Intravenous Unfractionated Heparin Infusion (GL2025_009)
• Continuous neurovascular observations

Definitive treatment would depend on the viability of 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 within 4–6 hours of ischaemia.

Surgical options

• Embolectomy (catheter or open)
• Bypass (if arterial thrombosis present)
• Amputation for treatment of the non-viable limb

Resources

• Björck M, Earnshaw JJ, Acosta S, et al. Editor's Choice - European Society for Vascular Surgery (ESVS) 2020 Clinical Practice Guidelines on the Management of Acute Limb Ischaemia. Eur J Vasc Endovasc Surg. 2020 Feb;59(2):173-218. DOI: 10.1016/j.ejvs.2019.09.006
• Clinical features and diagnosis of acute arterial occlusion of the lower extremities ( NSW Health login required)
  Source: UpToDate
• Gangrene
  Source: BMJ Best Practice
• Intravenous Unfractionated Heparin Infusion (GL2025_009)
  Source: NSW Health
• Neurovascular assessment
  Source: Agency for Clinical Innovation
• Peach G, Griffin M, Jones K G, et al. Diagnosis and Management of Peripheral Arterial Disease. BMJ 2012; 345 :e5208. DOI:10.1136/bmj.e5208

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