Critical limb ischaemia (CLI) is defined by which haemodynamic parameters in addition to clinical criteria (rest pain, ulceration, or gangrene)?
- A ABI >0.9 with claudication distance <200 m
- B ABI <0.7 with duplex-confirmed superficial femoral artery occlusion
- C Ankle systolic pressure <50 mmHg OR toe systolic pressure <30 mmHg (or toe brachial pressure index <0.4) ✓
- D ABI <0.9 with rest pain regardless of ankle pressure
Correct answer: C. Ankle systolic pressure <50 mmHg OR toe systolic pressure <30 mmHg (or toe brachial pressure index <0.4)
Explanation
Critical limb ischaemia (CLI) — now referred to as chronic limb-threatening ischaemia (CLTI) in updated ESVM/ACC/AHA guidelines — is defined by rest pain for >2 weeks or tissue loss (ulceration/gangrene) combined with haemodynamic confirmation: ankle systolic pressure <50 mmHg, toe systolic pressure <30 mmHg, or transcutaneous PO2 (TcPO2) <30 mmHg. Toe pressure measurement is preferred in diabetics where ankle pressure may be falsely elevated due to arterial calcification. CLI/CLTI carries 1-year amputation risk of 25–40% without revascularisation.
Reference: Bailey & Love's Short Practice of Surgery, 27th ed.
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