Synopsis
Recognise chronic limb-threatening ischaemia, confirm objective perfusion deficit, control infection and coordinate urgent limb-salvage or amputation decisions.
- CLTI is a clinical syndrome: objectively documented PAD with ischaemic rest pain lasting more than two weeks, gangrene, or non-healing ulceration lasting more than two weeks.
- The two-week definition identifies chronicity; never wait two weeks when an ischaemic or infected foot already needs urgent care.
- Refer every patient with suspected CLTI urgently to a vascular specialist unless medically urgent major amputation takes precedence.
Key red flags
New motor weakness, sensory loss, cold mottling or rapidly worsening pain indicates acute or acutely worsened ischaemia and demands immediate vascular review.
Ulceration with fever or sepsis, limb ischaemia, suspected deep soft-tissue or bone infection, or gangrene is an immediate diabetic-foot referral under NICE NG19.
Wet gangrene, crepitus, bullae, purulent tracking or systemic instability requires urgent operative source control alongside antimicrobials.
Rapid tissue loss, uncontrolled rest pain, heel necrosis or failure of a wound to progress despite care requires urgent reassessment of perfusion and salvageability.
Persistent distal forefoot pain is often worse with elevation or at night and relieved by dependency, with objective evidence of poor perfusion.
A non-healing ulcer, black dry gangrene or wet infected necrosis with PAD indicates threatened tissue rather than stable claudication.
Purulence, spreading erythema, deep tenderness, crepitus, systemic illness or wet gangrene requires immediate infection and vascular escalation.
Sudden severe pain, cold mottling, sensory loss or weakness indicates superimposed acute limb ischaemia and an immediate emergency.
Investigation priorities
Provide first-line objective evidence and quantify haemodynamic impairment in suspected CLTI.
Management branches
A person with diabetes has a painful toe ulcer for three weeks, absent pulses and an apparently normal ABPI.
- Inputs: record duration, rest pain, wound depth, gangrene, infection, neuropathy, pulses, Doppler signals, diabetes, renal disease, mobility and current systemic observations.
- Reasoning: the ulcer duration and PAD signs fit suspected CLTI, while diabetes makes calcific incompressibility and a falsely reassuring ABPI plausible.