Acute Limb Ischaemia
Acute limb ischaemia (ALI) is a sudden decrease in arterial perfusion threatening limb survival, with symptoms of less than 2 weeks. Management depends on Rutherford grade and cause. Give IV unfractionated heparin, analgesia, oxygen and fluids, then activate the ALI pathway with senior vascular decision-making. Grade I is usually conservative; IIa needs urgent imaging and planned revascularisation; IIb needs immediate revascularisation; III usually needs primary amputation or palliation.
Written September 23, 2026 · Mr Razhan K Ali
1 · UNDERSTAND — What is happening?
Definition and burden
ALI is sudden reduced limb perfusion with a potential threat to limb survival; symptoms are under 2 weeks. Longer duration is usually chronic limb ischaemia. ESVS cites Medicare data with in-hospital mortality 9.0%, one-year mortality about 41%, and one-year amputation 11.0%.
Causes
Native-artery ALI in Swedvasc: thrombosis 53%, embolism 44%, popliteal aneurysm 3%. Emboli are commonly associated with atrial fibrillation or ventricular thrombus. Other causes include graft/stent occlusion, dissection, trauma, vasculitis, popliteal entrapment, adventitial cystic disease, paradoxical embolism, thrombophilia, malignancy and low-output states.
Assessment
The 6 Ps are pain, pallor, pulselessness, poikilothermia/perishing cold, paraesthesia and paralysis, but they are rarely all present. Document Doppler signals, ABI, sensory and motor status, both limbs, abdominal/cardiac findings and frailty. Sensory loss means threatened limb; motor weakness means the limb is immediately threatened. Do not use admission CK or myoglobin alone to decide between revascularisation and primary amputation.
Rutherford ALI classification
| Grade | Sensory loss | Motor deficit | Prognosis |
|---|---|---|---|
| I viable | None | None | No immediate threat |
| IIa marginally threatened | None or minimal | None | Salvageable if promptly treated |
| IIb immediately threatened | More than toes | Mild/moderate | Salvageable if immediately revascularised |
| III irreversible | Profound, anaesthetic | Profound paralysis | Major tissue loss or permanent nerve damage inevitable |
Imaging
Image if it does not delay treatment. CTA is the recommended first-line anatomical imaging modality. Duplex or contrast-enhanced MRA may be alternatives depending on availability. DSA remains diagnostic and therapeutic in the same sitting.
2 · DECIDE — What do I do next?
- Suspect ALI clinically: sudden limb pain, coldness, pulse loss, paraesthesia, weakness or acute-onset claudication within 2 weeks.
- Start immediate measures: IV unfractionated heparin, oxygen, analgesia, IV fluids, baseline bloods, ECG and careful documentation.
- Grade the limb using Rutherford: sensory loss, motor deficit and venous Doppler signal decide urgency.
- Grade I: viable / acute-onset claudication. Conservative management, best medical therapy and supervised exercise; do not thrombolyse.
- Grade IIa: marginally threatened. Image urgently, usually CTA, then choose CDT, thrombectomy, open surgery or hybrid treatment.
- Grade IIb: immediately threatened. Immediate revascularisation. Image only if it will not delay reperfusion.
- Grade III: irreversible. Primary amputation or palliation is usual; revascularise only if genuinely uncertain and very recent.
Core ESVS decisions
| Situation | ESVS 2020 position | Class / Level |
|---|---|---|
| Grade I | CDT not recommended | Rec 23: III, B |
| Grade IIa | CDT should be considered as an alternative to surgery | Rec 24: I, A |
| Grade IIb | Urgent revascularisation mandatory; CDT may be considered if started promptly | Rec 25: IIb, B |
| Systemic IV thrombolysis | Not recommended | Rec 22: III, A |
| Aspiration / mechanical thrombectomy | Should be considered | Rec 33: IIa, C |
| Occluded bypass graft | Identify and treat the cause of graft occlusion | Rec 20: I, C |
Special situations
Thrombosed popliteal aneurysm usually needs saphenous vein bypass; lysis may improve tibial run-off; stent graft is not first-line. Acute aortic occlusion needs urgent revascularisation and anaesthesia/ICU planning. NCEPOD 2025 identified pathway delays and recommends a national ALI guideline.
3 · JUSTIFY — Why is that the correct decision?
Mechanism → grade → time → treatment. Nerve and muscle die within hours. Sensory loss means threatened limb; motor weakness means time-critical reperfusion. Evidence does not support one universal first-line technique for every patient.
Surgery vs thrombolysis
- Older RCTs and the 2018 Cochrane review do not show clear universal superiority of surgery or thrombolysis for limb salvage, amputation or death.
- Thrombolysis carries more bleeding, haemorrhagic stroke and distal embolisation.
- Surgery may restore flow faster in immediately threatened limbs but has operative and anaesthetic risk.
- ESVS therefore separates management by Rutherford grade rather than declaring one universal technique.
Landmark evidence
| Evidence | Practical message |
|---|---|
| Rochester 1994 | Small RCT; limb salvage similar, survival appeared better with thrombolysis. |
| STILE 1994 | Included many patients with symptoms over 14 days; acute graft occlusion subgroup appeared to benefit from lysis. |
| TOPAS 1998 | Amputation-free survival similar; bleeding and intracranial haemorrhage higher with lysis. |
| Cochrane 2018 | No clear difference in limb salvage, amputation or death; thrombolysis had more major haemorrhage and distal embolisation. |
Trial to know — ESTABLISH
ESTABLISH is a UK pragmatic multicentre RCT comparing open surgical versus endovascular strategy in lower-limb ALI. Primary outcome: amputation-free survival at 6 months. Registry: ISRCTN15236323.
4 · PERFORM — How is management executed?
- Senior vascular assessment: document Rutherford grade, Doppler findings, onset, sensory/motor status, frailty, ceiling of care and consent.
- Heparin: IV UFH 5000 IU or 70–100 IU/kg, then infusion adjusted by ACT or APTT. Use non-heparin anticoagulant if HIT is suspected.
- Supportive measures: oxygen, analgesia and IV rehydration.
- Grade and image: CTA first-line unless it will delay reperfusion in an immediately threatened limb.
- Open surgery: embolectomy may be done under local/regional anaesthesia with an anaesthetist present.
- Completion angiography: after open or endovascular revascularisation; treat residual inflow/outflow disease.
- CDT: ultrasound-guided access; rtPA or urokinase; no routine fibrinogen monitoring; no continuous systemic therapeutic heparinisation during lysis; stop for major bleeding.
- Consent: limb loss, death, bleeding, stroke/ICH with lysis, compartment syndrome/fasciotomy, reperfusion injury, renal failure, re-occlusion and further procedures.
5 · MANAGE — What happens next / what can go wrong?
Compartment syndrome
Diagnosis is clinical. Risk factors include ischaemia over 6 hours, young age, previous ALI, hypotension, raised CK, Rutherford IIb, inadequate backflow and positive fluid balance. Routine prophylactic fasciotomy is not recommended, but prophylactic four-compartment fasciotomy should be considered if ischaemia was profound or prolonged. Emergency fasciotomy should be within 2 hours of diagnosis and not delayed beyond 6 hours.
Other complications
| Complication | Recognise | Act |
|---|---|---|
| Reperfusion syndrome | Hyperkalaemia, acidosis, dark urine, high CK | Monitor potassium, CK and urine output; fluids; renal support when needed |
| Bleeding during lysis | Access haematoma, major bleeding or ICH | Major bleeding: stop lysis. |
| Re-occlusion | Loss of Doppler signal or recurrent symptoms | Re-image and treat the culprit lesion, not just the clot. |
After limb salvage
- Embolic ALI: ECG, 24-hour monitoring, echocardiography and CTA of the whole aorta if no cardiac source; long-term anticoagulation if AF/intracardiac thrombus.
- Thrombotic ALI or failed previous revascularisation: long-term antiplatelet or anticoagulant plus statin; stop smoking.
- Under 60 with thrombotic ALI: consider malignancy and thrombophilia, especially with simultaneous venous thrombosis.
6 · REMEMBER — What must I retain?
- ALI = under 2 weeks; one-year mortality is about 40%.
- Start UFH 5000 IU or 70–100 IU/kg, oxygen, analgesia and IV fluids while grading the limb.
- Grade I: no sensory/motor loss → conservative; no lysis.
- Grade IIa: minimal/no sensory loss, no weakness → CTA and planned revascularisation; CDT is Class I A as an alternative.
- Grade IIb: sensory loss beyond toes or motor weakness → immediate revascularisation.
- Grade III: profound anaesthesia/paralysis, no venous signal → usually primary amputation or palliation.
- Lysis vs surgery: no universal winner; lysis bleeds more; surgery restores flow faster.
- Occlusion length: under 30 cm tends to favour surgery; over 30 cm tends to favour lysis.
- Fasciotomy: four compartments, within 2 hours of diagnosis, never delayed beyond 6 hours.
- Treat the cause: anticoagulate AF/intracardiac thrombus; statin plus antiplatelet or anticoagulant after thrombosis.
Memory hook: Can walk — wait. Can't feel — hurry. Can't move — open/endovascular now. Can't bend — let it go.
References
- 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;59(2):173-218. doi:10.1016/j.ejvs.2019.09.006. PMID: 31899099.
- Rutherford RB, Baker JD, Ernst C, et al. Recommended standards for reports dealing with lower extremity ischemia: revised version. J Vasc Surg. 1997;26(3):517-538. doi:10.1016/S0741-5214(97)70045-4. PMID: 9308598.
- Boyle JR, Atkins ER, Birmpili P, et al. A Best Practice Clinical Care Pathway for Peripheral Arterial Disease. J Vasc Soc GB Irel. 2022;1(Suppl 3):S1-S13. doi:10.54522/jvsgbi.2022.017.
- National Confidential Enquiry into Patient Outcome and Death. Risking Life and Limb: A review of the quality of care provided to adults with acute limb ischaemia. London: NCEPOD; 2025.
- Ouriel K, Shortell CK, DeWeese JA, et al. A comparison of thrombolytic therapy with operative revascularization in the initial treatment of acute peripheral arterial ischemia. J Vasc Surg. 1994;19(6):1021-1030. doi:10.1016/S0741-5214(94)70214-4. PMID: 8201703.
- The STILE Investigators. Results of a prospective randomized trial evaluating surgery versus thrombolysis for ischemia of the lower extremity. Ann Surg. 1994;220(3):251-266. doi:10.1097/00000658-199409000-00003.
- Ouriel K, Veith FJ, Sasahara AA; TOPAS Investigators. A comparison of recombinant urokinase with vascular surgery as initial treatment for acute arterial occlusion of the legs. N Engl J Med. 1998;338(16):1105-1111. doi:10.1056/NEJM199804163381603.
- Darwood R, Berridge DC, Kessel DO, Robertson I, Forster R. Surgery versus thrombolysis for initial management of acute limb ischaemia. Cochrane Database Syst Rev. 2018;8(8):CD002784. doi:10.1002/14651858.CD002784.pub3. PMID: 30095170.
- Maldonado TS, Powell A, Wendorff H, et al. One-year limb salvage and quality of life following mechanical aspiration thrombectomy in patients with acute lower extremity ischemia. J Vasc Surg. 2024;80(4):1159-1168.e5. doi:10.1016/j.jvs.2024.05.043. PMID: 38914349.
- ESTABLISH Trial. Endovascular strategy versus Surgical strategy for the Treatment for Acute Limb Ischaemia. ISRCTN15236323. doi:10.1186/ISRCTN15236323.