Acute Limb Ischaemia

Acute limb ischaemia is defined by the 6 Ps: Pain, Pallor, Pulselessness, Paraesthesia, Paralysis, and Perishingly cold. Rutherford IIb (motor deficit/paralysis or fixed mottling) demands emergency revascularisation within hours to prevent…

Rutherford Classification / ESVS Guidelines

The pathway

1 · 6 Ps assessment

Pain: severe, acute onset — may be absent if profound ischaemia (nerve death)
Pallor: mottled or chalk-white skin
Pulseless: compare to contralateral limb with hand-held Doppler
Paraesthesia: pins and needles — indicates sensory nerve ischaemia
Paralysis: inability to move foot/toes — indicates motor nerve ischaemia, surgical emergency
Perishingly cold: cool to touch compared to contralateral limb

2 · Rutherford classification

Class I (Viable): no immediate threat; audible Doppler signals; no sensory/motor deficit
Class IIa (Marginally threatened): salvageable with prompt treatment; mild sensory deficit; no motor deficit
Class IIb (Immediately threatened): paralysis and/or fixed mottling; audible venous Doppler only; hours to irreversibility
Class III (Irreversible): permanent nerve and muscle damage; no Doppler signals; discuss primary amputation

3 · IV heparin immediately

Unfractionated heparin 5000 IU IV bolus immediately on diagnosis
Then heparin infusion (typically 1000–1500 IU/hr) adjusted to APTT 60–100s
Prevents propagation of thrombus and protects collateral circulation

4 · Urgent vascular surgery referral

Bleep vascular surgery immediately — this is a time-critical emergency
Document exact time of symptom onset
Do not wait for imaging if Rutherford IIb — go directly to theatre if clinically clear

5 · Imaging

Duplex USS: rapid bedside assessment of flow
CT angiography: gold standard for planning revascularisation — only if patient stable and Rutherford I/IIa
On-table angiography: for Rutherford IIb going to theatre

6 · Revascularisation

Embolic cause (atrial fibrillation, recent MI, cardiac thrombus): Fogarty catheter embolectomy under LA
Thrombotic cause (underlying PAD, bypass graft occlusion): bypass grafting or thrombolysis (IIa only)
Catheter-directed thrombolysis: for Rutherford IIa with thrombotic occlusion — alteplase intra-arterially

7 · Post-reperfusion monitoring

Compartment syndrome: increasing pain, tense compartments, pain on passive stretch — emergency fasciotomy
Rhabdomyolysis: rising CK, myoglobinuria (dark urine), AKI — IV fluids, monitor urine output >1ml/kg/hr
Reperfusion hyperkalaemia: ECG monitoring, treat as per hyperkalaemia protocol

Drugs

Drug	Dose	Route	Notes
Unfractionated heparin	5000 IU bolus then infusion	IV	Start immediately. Infusion titrated to APTT 60–100s. Do not use LMWH (cannot be reversed rapidly).
Morphine	5–10mg	IV	Titrate to pain. Severe ischaemic pain is intense.
Aspirin	300mg	PO	Post-operatively once haemostasis confirmed. Then 75mg OD long-term.
Crystalloid (0.9% NaCl or Hartmann's)	1–2L	IV	IV resuscitation and forced diuresis post-reperfusion to protect against rhabdomyolysis-induced AKI.

When to escalate

Rutherford IIb (paralysis present) — emergency theatre within hours,Fixed mottled skin (Rutherford III) — discuss primary amputation with senior vascular surgeon,Compartment syndrome post-reperfusion — emergency fasciotomy,Rhabdomyolysis (rising CK/myoglobinuria/AKI) — high-volume IV fluids, nephrology input,Failure of embolectomy to restore perfusion — proceed to bypass or angiography

Reference: ESVS 2020 Clinical Practice Guidelines on Acute Limb Ischaemia

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