Chronic Limb-Threatening Ischaemia (CLTI) Management
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Direct answer
Rest pain that wakes the patient at night and eases only when the foot dangles over the bed edge, with or without ulceration or gangrene, defines chronic limb-threatening ischaemia — the term the 2019 Global Vascular Guidelines substituted for "critical limb ischaemia". Objective support comes from a toe pressure around 30 mmHg or less, or transcutaneous oxygen below about 25 mmHg, because the ankle–brachial index is unreliable in diabetics. Management follows the PLAN framework — Patient risk, Limb severity staged by WIfI, ANatomic complexity staged by GLASS — with revascularisation for salvageable limbs, wound and infection control alongside, and primary amputation or palliation for limbs or patients beyond salvage. The BEST-CLI trial in 2022 sharpened the conduit choice: with an adequate great saphenous vein, surgical bypass outperformed an endovascular-first strategy.
What you must remember
- WIfI grades Wound, Ischaemia and foot Infection each from 0 to 3, combining into clinical stages 1–5 that predict one-year amputation risk independent of anatomy.
- GLASS grades the arterial tree (femoropopliteal and tibial) into stages I–III; higher stages predict worse technical success and durability of endovascular therapy.
- BEST-CLI: with a good great saphenous vein, bypass reduced the composite of major adverse limb events or death (roughly 43% versus 57% over a median near three years, hazard ratio about 0.68); without usable vein, endovascular-first and bypass performed similarly.
- Infection comes first: drain abscesses and debride necrotic tissue with culture-directed antibiotics before or alongside revascularisation.
- The angiosome concept — direct versus indirect revascularisation of the ulcer's arterial territory — remains debated but is examinable; tibial target choice influences wound healing.
- A non-ambulatory, cognitively impaired patient with an unsalvageable limb is served by primary amputation or palliation, not by a doomed bypass.
- After revascularisation: antiplatelet and statin, duplex surveillance, offloading and podiatry — a limb is saved repeatedly, not once.
- Toe pressure at or below 30 mmHg, or transcutaneous oxygen near 25 mmHg, separates true limb threat from non-vascular rest pain.
A typical exam case
A 62-year-old man with type 2 diabetes and a 40-pack-year history has a gangrenous second toe and night-time forefoot burning relieved by dependency. The ankle–brachial index reads 1.2 — falsely reassuring because of calcified tibials — so toe pressure is measured at 28 mmHg. WIfI scoring assigns Wound 2, Ischaemia 3, Infection 1: clinical stage 4, a limb that will be lost without revascularisation. Step one is sepsis control: the wet toe is debrided, deep cultures sent and broad-spectrum antibiotics started. Step two is anatomy: duplex and CT angiography show a long femoropopliteal occlusion with diseased tibials, GLASS stage II–III, and the vein map shows a good great saphenous vein. Following BEST-CLI, vein bypass to the best target tibial artery is chosen over endovascular-first. Step three, once flow is restored and the foot is perfused, the toe is amputated at the level that now heals, and the patient enters surveillance and foot care. Had the vein been poor, the calculus would shift to best endovascular therapy; had the patient been bed-bound with a fixed flexion contracture, a primary below-knee amputation would have been the kinder operation.
Where students slip
Two slips dominate. The first is the diabetic ankle–brachial index above 1.3 accepted as normal — in suspected limb threat it means non-compressible vessels, and the answer is toe pressures or transcutaneous oximetry. The second is sequencing: revascularising a pus-filled foot without drainage first, or amputating before perfusion is assessed. The disciplined order — control infection, image anatomy, restore inflow, then decide the amputation level — is what the examiner wants spoken aloud. A candidate who adds that timely revascularisation can convert a planned above-knee amputation into a transmetatarsal one earns the bonus mark.
Frequently asked questions
What defines chronic limb-threatening ischaemia?
Peripheral arterial disease with rest pain requiring analgesia or dependency, or tissue loss in the form of ulceration or gangrene, supported by toe pressure around 30 mmHg or below.
What does WIfI stage?
The limb, combining Wound, Ischaemia and foot Infection severity into five clinical stages that predict amputation risk, independent of anatomic disease burden.
What did BEST-CLI conclude?
When an adequate great saphenous vein exists, surgical bypass beat an endovascular-first strategy for major adverse limb events and death; without adequate vein, neither strategy was superior.
Which patients go to primary amputation rather than revascularisation?
Non-ambulatory or cognitively impaired patients, unsalvageable limbs, or anatomy lacking a target or conduit — with palliation where even amputation serves no goal.
Why must infection be controlled before revascularisation?
Because pus under pressure thromboses grafts and disseminates bacteraemia; drainage and debridement first protect the reconstruction and the patient.
What is the angiosome concept?
Revascularising the artery that directly supplies the wound's anatomic territory; whether direct beats indirect flow remains debated, but the tibial target chosen influences healing.