Critical limb ischaemia (CLI) is defined by which haemodynamic parameters, and what distinguishes it from intermittent claudication in terms of revascularisation urgency?
- A CLI = ABI <0.6 with claudication at <100 metres; can be managed conservatively for 6 months before intervention
- B CLI = ABI <0.4 OR ankle pressure <50 mmHg (in non-diabetics) OR toe pressure <30 mmHg, with rest pain >2 weeks or tissue loss; requires revascularisation within days-weeks to prevent amputation ✓
- C CLI = any ABI <0.9 with rest pain; requires immediate emergent bypass surgery
- D CLI = ABI <0.5 with absent pedal pulses; toe amputation is first-line management
Explanation
Critical limb ischaemia (now termed Chronic Limb-Threatening Ischaemia — CLTI per updated TASC guidelines) is defined by rest pain persisting >2 weeks requiring opioid analgesia, ankle pressure <50 mmHg or toe pressure <30 mmHg (non-diabetics), or ABI <0.4 with or without tissue loss (ulcer/gangrene). CLI carries a 1-year amputation rate of 25-30% and mortality of 20-25% without revascularisation. Revascularisation (endovascular or bypass depending on anatomy) is urgent within days-weeks. Intermittent claudication (ABI 0.4-0.9, reproducible exercise-induced calf pain) is treated conservatively for 3-6 months with supervised exercise therapy as first line.
Reference: Bailey & Love's Short Practice of Surgery, 27th ed.
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Written and medically reviewed by the StethoPrep medical team.