Critical Limb Ischaemia

• • moving from non-critical to critical limb ischaemia signifies a significant worsening of the underlying pathology
  • Usually this means a continual growth and development of the atheroma so that the blood vessel lumen is significantly occluded to the point that not all tissues dependent on that blood supply receive the blood they need to meet their metabolic demands
  • As a result the tissues become non-viable and a degree of tissue death occurs
• CLI:

  • Critical Limb Ischaemia (CLI) is typified by at least one of the following features occurring in an individual in whom PAD has been conclusively diagnosed by MRI scanning, thermal imaging, ankle brachial pressure index (ABPi) or angiography etc:
  • Rest pain
  • Ulceration
  • Gangrene
• Critical Limb Ischaemia:

  • typified by:
  • rest pain + ulceration
  • associated with excessively high risk for cardiovascular events
• Critical Limb Ischaemia:

  • represents a progression/worsening of underlying pathology
  • the risk of an acute myocardial infarction, cerebrovascular accident or death from cardiovascular disease is 3 times higher in those with critical limb ischaemia compared to those with intermittent claudication
  • reinforces needs to prevent development of critical limb ischaemia and to manage cardiovascular disease risk factors
• Definition of critical limb ischaemia:

  • chronic ischaemia with at least one of:
  • rest pain
  • ulceration
  • gangrene
  • in one or both legs secondary to objectively proven occlusive disease
  • time for revascularisation procedures or amputation
• CLI & Rest Pain:

  • a continuous relentless pain even at rest
  • is an exacerbated mismatch of tissue ends and blood supply
  • rest pain can be worse at night as during night:
  • metabolic demands of tissues decrease -> HR and BP decreases
  • as BP decreases -> perfusion decreases -> decreases oxygen reaching tissues (ischaemia) -> activation of pain receptors
  • people with rest pain hang their legs over the edge of the bed to put their legs into a gravity dependent position to use a gravity assist on arterial blood flow to counteract the drop in perfusion during the night
• Treatment of Rest Pain:

  • opiates - morphine, diamorphine, pethidine, dihydrocodeine etc
  • lumbar sympathectomy - usually not effective enough to make a valid difference
  • angioplasty or by-pass grafting
  • amputation
  • life-style modification
• Ulceration & Gangrene:

  • arterial ulcers are described as being punched out
  • deep and painful
  • tend to be found on the dorsum of feet or the pretibial area
  • inflammation around the wound
  • wounds are debrided / cutting off necrotic tissue to allow healthy tissue to grow
  • pts provided with antibiotics
  • vascular reconstruction needs to take part to improve perfusion to surrounding tissues
  • gangrenes are when the tissue become necrotic, changing colour to a cyanised, hypoxic colour and then to a black colour
• Gangrenous tissue must be excised:

  • the treatment for gangrene is amputation
  • why is it necessary to amputate gangrenous body parts?
  • prevent spread of infection
  • reduce pain
  • promote healing
• NICE guidelines management critical limb ischaemia:

  • continued lifestyle modification
  • analgesia
  • angioplasty +/- stent
  • bypass grafting
  • amputation
  • cardiovascular drugs e.g. antiplatelets, statins
• • As well as clearly indicating a worsening of peripheral vascular pathology, the development of CLI pinpoints the time when an individual’s risk of having an AMI, CVA or death from any CVD is a staggering 3 times greater than individuals with non-critical limb ischaemia
  • The incidence of CLI clearly identifies the point at which conservative management such as drugs and exercise therapy are no longer going to be effective
  • Management strategies need to change