What You Should Know About Critical Limb Ischemia

Critical limb ischemia or "CLI" is a condition where one or more arteries become severely blocked in the legs, causing a significant reduction in blood flow to the lower extremities.

critical limb ischemia guide

- Image courtesy of Rondae Productions

It is a type of peripheral arterial disease that is caused by atherosclerosis (the hardening and narrowing of the arteries due to the build-up of cholesterol and fatty plaques).

This type of foot ischemia should be taken seriously, so we've constructed this short explainer guide to cover the basics of CLI.

What are the main symptoms of critical limb ischemia?

In mild cases, critical limb ischemia is often asymptomatic. If your limb ischemia diagnosis is Stage 1, then there is no threat to losing sensations in the limb, and if treated you can make a full recovery.

However, as the condition worsens over time, it can begin to cause a range of symptoms. The symptom profile of critical limb ischemia changes as the condition gets more severe. 

The symptoms of critical limb ischemia include:

  • Intermittent claudication
  • Absent pulse in the legs or feet
  • Dryness of the skin
  • Thickening of the toenails
  • Numbness in the feet
  • Pain in the lower legs and feet when at rest
  • Stage 4 - ulceration or gangrene in one of both of the legs

Intermittent claudication describes cramping in the thighs, calves, or buttocks that occur after walking a certain distance. Usually, people need to rest for a few minutes in order for the claudication to stop.

How is critical limb ischemia diagnosed?

Doctors can confirm critical limb ischemia by using something known as the Buerger’s test. This test involves lying a patient down in a supine position and raising their legs until the skin turns a pale color.

The Buerger's Test, courtesy of Internal Medicine Made Easy on YouTube.

The leg is then lowered slowly and the angle at which color (blood) returns to the legs is measured (the Buerger’s angle).

If the Buerger’s angle is less than 20 degrees, critical limb ischemia can be confirmed.

Doctors or specialist vascular nurses can also check the temperature of the legs, and measure the ankle brachial pressure index (ABPI). If the legs are cold and ABPIs are below 0.5, it indicates critical limb ischemia, especially if combined with intermittent claudication, ulcerations, or gangrene in the legs.

ABPIs are measured using a Doppler ultrasound machine. If further confirmation is required, a patient might also be sent for a CT or MR angiogram.

An angiogram is a type of x-ray that uses contrast dyes to looks at the flow of blood through blood vessels.

Who is most susceptible to critical limb ischemia?

According to one National Institutes of Health study, the prevalence of symptoms attributed to peripheral artery disease is as high as 36% in men, and 26% in women. In general, the occurrence of PAD symptoms increase with age.

The increased risk is due to the decreased vascular function that is often associated with old age. The risk of atherosclerosis and vascular disease increases as a person reaches their 70s and this can eventually lead to critical limb ischemia.

There are a few risk factors that increase a person’s risk of developing critical limb ischemia, such as:

  • Smoking
  • Hypertension (high blood pressure)
  • Hyperlipidemia (high blood lipids)
  • Diabetes mellitus
  • Obesity
  • Sedentary lifestyle
  • Family history of claudication or heart disease
  • Old age

What are the treatment options for critical limb ischemia?

If left untreated, critical limb ischemia will get worse. In severe cases where non-healing wounds and gangrene are present, limb amputation may be necessary.

Treatment options include endovascular therapy or surgery. If the ischemia is mild, endovascular repair might be possible to treat the condition. The most suitable treatment also depends on the location and severity of the arterial blockage.

Here are some of the most commonly-used treatment options for those with critical limb ischemia:


This procedure involves the insertion of a small balloon into the groin. It is fed down the affected artery and inflated using a saline solution to expand the artery and resolve the occlusion.


This type of procedure also uses an inflated balloon, but instead of using a saline solution, the blood is inflated using nitrous oxide gas. The gas freezes the built-up plaques on the artery walls, preventing it from growing any further and improving blood flow through the artery.


Mesh tubes that are made from metal called stents can be used to dilate the affected artery and hold it open, enabling blood to flow more easily through the vessel.

This is usually performed after the artery has been opened using balloon angioplasty but self-expanding stents can also be used.


When there are open wounds, ulcers, or gangrenous tissue, endovascular options might not be suitable and surgical procedures might be required. Surgery usually involves bypassing the area of the affected artery using a vein or synthetic graft. The vein or graft gets attached to the artery on either side of the blockage, which allows blood to bypass the affected area.

    In severe cases, when there is necrotic tissue in the lower legs and feet, amputation might be required to reduce the risk of further complications.

    How long is the recovery process from critical limb ischemia treatment?

    The recovery period after the treatment of critical limb ischemia depends on the treatment option that has been used.

    For endovascular procedures, recovery might take a couple of weeks. For surgical procedures, a patient might need to stay in hospital for a week, followed by several weeks of at-home recovery.

    Most patients require life-long care after critical limb ischemia. They will need regular follow-ups and ongoing help from nurses, dietitians, and therapists.

    Even with ongoing care, the survival rates after critical limb ischemia are around 40%, with fatalities usually resulting from cardiovascular disease.

    Can critical limb ischemia be prevented?

    The best way to reduce the risk of critical limb ischemia is to live as healthy a lifestyle as possible. Maintaining a healthy weight, exercising regularly, avoiding smoking, and managing long-term conditions are important to preventing the condition. Each of these factors become increasingly important the older a person becomes.

    Have any questions about critical limb ischemia, or would you like to schedule an appointment to see one of our Southern California radiologists? 

    Give us a call, or schedule an appointment today!