Acute Limb Ischemia

Overview

Acute limb ischemia is a sudden and severe reduction in blood flow to an arm or leg, usually because an artery has become abruptly blocked. Without enough blood, the muscles, nerves, and tissues of the limb are starved of oxygen and begin to suffer damage within hours.

This is a true medical emergency. The longer blood flow is cut off, the greater the risk of permanent tissue damage and, ultimately, loss of the limb. Rapid recognition and treatment to restore blood flow can save the limb and the person's life. Anyone with the sudden onset of a painful, cold, pale, or numb arm or leg should seek emergency care immediately by calling emergency services.

Time is the most important factor in acute limb ischemia. Muscle and nerve tissue can begin to suffer irreversible damage within a few hours of losing their blood supply, so the outcome often depends on how quickly blood flow is restored. This makes acute limb ischemia one of the situations where every minute counts, and where delaying care in the hope that symptoms will pass can lead to permanent harm.

Symptoms

The classic warning signs are remembered as the six P's and tend to come on suddenly.

• Pain: Sudden, severe pain in the affected limb
• Pallor: The limb looks pale or white
• Pulselessness: Weak or absent pulse in the limb
• Paresthesia: Numbness, tingling, or loss of sensation
• Paralysis: Weakness or inability to move the limb
• Poikilothermia (perishing cold): The limb feels cold

These symptoms signal a limb-threatening emergency. Do not wait to see if they improve; call emergency services right away.

Causes

Acute limb ischemia happens when an artery supplying the limb is suddenly blocked.

• Embolism: A clot that forms elsewhere, often in the heart due to an irregular heartbeat (atrial fibrillation), travels through the bloodstream and lodges in a limb artery.
• Thrombosis: A clot forms directly on a narrowed, diseased artery, often in someone with existing peripheral artery disease.
• Trauma or graft failure: Injury to an artery or the sudden clotting of a bypass graft or stent.

The result in each case is an abrupt halt to blood flow that quickly endangers the limb.

Risk Factors

• Atrial fibrillation or other irregular heart rhythms
• Peripheral artery disease and atherosclerosis
• Previous blood clots or clotting disorders
• Recent vascular surgery, bypass grafts, or stents
• Smoking, diabetes, high blood pressure, and high cholesterol
• Recent heart attack or heart valve disease

Diagnosis

Because time is critical, diagnosis is often made quickly at the bedside and confirmed with rapid imaging.

• Physical examination: Checking pulses, color, temperature, sensation, and movement of the limb.
• Doppler ultrasound: A handheld device to detect blood flow in the arteries.
• CT or catheter angiography: Imaging of the arteries to pinpoint the location of the blockage.
• Blood and heart tests: To look for a source of the clot, such as an irregular heartbeat.

Treatment

Treatment is urgent and aims to restore blood flow as fast as possible.

• Blood thinners: Given immediately to stop the clot from growing and prevent new clots.
• Clot-dissolving therapy: Medication delivered through a catheter to break up the clot.
• Procedures to remove the clot: Surgery or a catheter-based technique to physically remove or extract the blockage and restore flow.
• Bypass surgery: Rerouting blood around a blocked segment when needed.
• Treating the underlying cause: For example, managing atrial fibrillation to prevent future clots.

In severe cases where the limb cannot be saved, amputation may be necessary, which is why early treatment is so important.

Prevention

• Manage atrial fibrillation and take prescribed blood thinners as directed
• Control blood pressure, blood sugar, and cholesterol
• Stop smoking
• Treat peripheral artery disease and follow your care plan
• Attend follow-up after vascular surgery, grafts, or stents
• Seek immediate care at the first sign of a sudden cold, painful, or numb limb

When to See a Doctor

Acute limb ischemia is a medical emergency. Call emergency services immediately if you have the sudden onset of severe pain, paleness, coldness, numbness, weakness, or loss of pulse in an arm or leg. Every hour without blood flow increases the risk of permanent damage or loss of the limb. Do not wait to see whether symptoms improve, and do not drive yourself if symptoms are severe.

Related Topics

Frequently Asked Questions

References

1. MedlinePlus, U.S. National Library of Medicine. Arterial embolism.
2. Society for Vascular Surgery. Acute limb ischemia.
3. Mayo Clinic. Peripheral artery disease (PAD) — Symptoms and causes.
4. National Heart, Lung, and Blood Institute (NHLBI). Peripheral Artery Disease.