What Is Critical Limb Ischemia (CLI) vs. Acute Limb Ischemia?

Symptoms of critical limb ischemia include:

• Severe pain in the legs and feet while a person is not moving (called ischemic rest pain)
• Open sores, skin infections, or ulcers on the feet and legs that will not heal
• Numbness in the feet
• Shiny, smooth, dry skin of the legs or feet
• Thickening of the toenails
• Diminished or absent pulse in the legs or feet
• Dry gangrene (dry, black skin) of the legs or feet

Symptoms of acute limb ischemia are often referred to as the “six Ps” and include: 

• Pain that is located in the extremity and gradually increases in severity, but may eventually decrease due to progressive ischemic sensory loss
• Pallor: pale or mottled skin 
• Poikilothermia: cool skin
• Pulselessness: diminished or absent pulse
• Paresthesia: numbness and tingling
• Paralysis

Critical limb ischemia is an advanced stage of peripheral arterial disease (PAD), which is caused by the hardening and narrowing of the arteries over time due to the buildup of fatty deposits called plaque (by atherosclerosis).

Risk factors for chronic limb ischemia are the same as those for atherosclerosis, including:

• Age
• Smoking
• Diabetes
• Being overweight or obese
• Sedentary lifestyle
• High cholesterol
• High blood pressure (hypertension)
• Family history of atherosclerosis or claudication

Causes of acute limb ischemia include: 

• Blockage in a blood vessel (embolism) by such as by a blood clot, a fat globule, a bubble of air or other gas, or foreign material
• Blood clot (thrombosis)
• Peripheral artery disease due to atherosclerosis
• Tear in the lining of an aortic or peripheral artery (dissection)
• Major trauma
• Conditions that cause vasospasm 
• Raynaud phenomenon
• Shock (e.g., meningococcal sepsis, cardiogenic shock)
• Administration of vasoactive drugs

Critical limb ischemia and acute limb ischemia are diagnosed with a patient history and physical examination. The blockages associated with limb ischemia are located using one or more of the following methods:

• Auscultation
• Ankle-brachial index (ABI)
• Doppler ultrasound 
• Computerized tomography (CT) angiography
• Magnetic resonance angiography (MR angiography)
• Angiogram

Immediate treatment is needed for severe critical or acute limb ischemia to re-establish blood flow to the affected area and to preserve the limb.

Treatments for chronic limb ischemia include:

• Angioplasty
  • A tiny balloon is inserted through a puncture in the groin and is inflated using a saline solution, to open the artery
    • Cutting balloon: The balloon is imbedded with micro-blades that cut the surface of the plaque, reducing the force necessary to dilate the vessel
    • Cold balloon (CryoPlasty): The balloon is inflated using nitrous oxide which freezes the plaque
• Stents
  • Metal mesh tubes are used to provide scaffolding after an artery has been opened using a balloon angioplasty
    • Balloon-expanded: A balloon is use to expand the stent
    • Self-expanding: Compressed stents expand upon release
• Laser atherectomy: the tip of a laser probe is used to vaporize small bits of plaque 
• Directional atherectomy: A catheter with a rotating cutting blade physically removes plaque from the artery, opening the flow channel
• Surgical treatments
  • Wounds or ulcers may require surgical procedures or other follow-up care
  • Surgical treatment may be recommended if endovascular therapy is not beneficial for the arterial blockages 
  • Often involves bypass around the diseased segment with either a vein from the patient or a synthetic graft

Treatments for acute limb ischemia include: 

• Intravenous (IV) injection of unfractionated heparin 
• Surgical treatment 
• Thromboembolectomy
• Bypass surgery
• Endovascular treatment 
• Catheter-directed thrombolysis (CDT)
• Percutaneous thrombus aspiration
• Stent placement
• Hybrid treatment that combines both therapies