Acute limb ischaemia

Acute Limb Ischaemia (ALI) is a rapid decrease in blood flow to a limb, typically an arm or leg, that threatens its viability. This condition is a medical emergency requiring immediate attention to prevent limb loss, disability, or even death. The primary cause of ALI is a sudden blockage in the arteries, often due to a blood clot (thrombosis) or embolism. Other causes may include severe injury, arterial spasm, or external compression of an artery.

Causes

Acute limb ischaemia is most commonly caused by:

• Thrombosis: The formation of a blood clot within the arteries supplying the limb.
• Embolism: A blood clot that travels from another part of the body and lodges in the limb's arteries.
• Atherosclerosis: The narrowing of arteries due to the buildup of plaque, which can lead to thrombosis.
• Trauma: Severe injuries that directly damage the arteries.
• Arterial spasm: A sudden constriction of the artery, reducing blood flow.

Symptoms

The classic symptoms of acute limb ischaemia are often described by the "six Ps":

• Pain: Severe, unrelenting pain in the affected limb.
• Pallor: The limb appears pale due to lack of blood flow.
• Pulselessness: Absence of a detectable pulse in the limb.
• Paresthesia: Tingling, prickling, or numbness in the limb.
• Paralysis: Loss of function in the affected limb.
• Poikilothermia: The limb feels cooler than the rest of the body.

Diagnosis

Diagnosis of acute limb ischaemia involves a combination of clinical assessment and imaging studies. Key diagnostic tools include:

• Physical examination: Assessing the six Ps and looking for signs of compromised blood flow.
• Doppler ultrasound: A non-invasive test that uses sound waves to visualize blood flow in the arteries.
• Angiography: An imaging test that involves injecting a contrast dye into the arteries to visualize blockages or narrowing.

Treatment

The treatment of ALI aims to restore blood flow to the affected limb as quickly as possible to prevent tissue death and loss of the limb. Treatment options include:

• Anticoagulation therapy: Medications such as heparin to prevent further clotting.
• Thrombolysis: The use of drugs to dissolve blood clots.
• Surgical embolectomy: The surgical removal of a clot.
• Bypass surgery: Creating a new route for blood flow around the blocked artery.
• Amputation: In severe cases where the limb cannot be saved, amputation may be necessary.

Prevention

Preventing acute limb ischaemia involves managing risk factors for vascular disease, such as:

• Controlling diabetes, hypertension, and hyperlipidemia.
• Quitting smoking.
• Maintaining a healthy weight and diet.
• Regular exercise.

Prognosis

The prognosis for individuals with acute limb ischaemia varies depending on the severity of the blockage, the time to treatment, and the presence of underlying health conditions. Early diagnosis and treatment are critical for a favorable outcome.