Clinical Features
Lower limb ischaemia is a condition in which the arterial blood flow supplying the legs and feet is reduced or obstructed, normally because of arteriosclerosis.
Clinical examination will elicit the symptoms and signs. Particular attention would normally be paid to the major peripheral pulses such as -:
- In the groins (femoral artery)
- Behind the knees (popliteal artery)
- At the top of the foot (dorsalis pedis)
- Behind the ankle (posterior tibial)
A weak or absent pulse will be present beyond the blockage. The temperature and colour of the limbs is noted, and a stethoscope is used to listen for turbulence (or bruits) where an artery may be narrowed.
Lower limb ischaemia may be:
- Acute (caused by embolus, thrombus or trauma, such as damage from a fractured spike of bone, crush injury, etc).
- Chronic (mostly due to arteriosclerosis), or
- Compartment Syndrome (an orthopaedic emergency).
Critical Ischaemia
This occurs when the ischaemia becomes much worse as the arterial supply is much more severely reduced. It may occur without preceding intermittent claudication. The definition is:
- Rest (or night) pain, requiring strong pain relief, and/ or gangrenous change or ulceration, present for more than 2 weeks,
- Reduced blood pressure in the leg.
Symptoms and Signs
- Rest pain
Rest pain usually occurs in the skin of the foot, is burning in character and occurs on resting in bed. The pain is severe and can wake the person. It is relieved by hanging the leg over the edge of the bed. - Failure of small and trivial injuries to heal
These injuries may become infected, the infections may become serious quickly, and wounds may take weeks or months to heal. - Ulcers
Peripheral vascular disease can cause ulcers because of tissue ischaemia, and the presence of ulcers often signifies that severe ischaemia is present. Arterial ulcers are usually confined to a toe or a limited part of the forefoot. - Gangrene
When the colour of the affected limb changes from pale to a dusky colour, this signals worsening of the ischaemia, with pre-gangrene. Patchy and localised necrosis (death) of the tissue may develop. There may be signs of previous loss of tissue (toe or part of the foot).
A quarter of these people die each year from cardiovascular disease, as there is likely to be widespread arteriosclerosis concurrently present.
Acute Critical Limb Ischaemia
This is an emergency situation, in which the whole limb may be at risk. It is normally caused by a:
- Thrombus (a blood clot attached to the vessel wall)
- Embolus (a clot thrown up from the heart because of atrial fibrillation, or because of an infarct),
Or
- Trauma, such as crush injury. The symptoms and signs of this can be summarized as the 6 “P’s”:
- Pale
- Pulseless
- Paralysed
- Painful
- Paraesthetic (pins and needles)
- Perishing with cold
This requires urgent treatment, or the person loses the leg.
Chronic Critical Limb Ischaemia
Chronic arterial insufficiency of the lower limbs presents as muscular pain in the calf, brought on, and worsened by exercise. The person limps with pain, it is known as intermittent claudication. The pain forces the person to stop walking, and this allows the pain to subside in a minute or two. If the exercise is resumed, the pain recurs after walking the same distance on a flat surface. This is known as the claudication distance, and is reasonably constant. The pain is almost always in the calf, but can occur in the buttock, hip, thigh or foot.
Symptoms
Often both limbs are affected, but normally one is more severely affected than the other, that is they are asymmetrically involved.
Chronic lower limb ischaemia presents with the following symptoms (what the person complains of):
- Leg pain (intermittent claudication)
On walking or exercise intermittent claudication is regular, predictable and relieved by rest. This rest period is fairly constant, and can take up to 5 minutes. - Numb legs and/ or feet
This is a direct result of poor circulation to the lower limb. Damage is caused to the tissues of the affected limb, including nerves, skin, nails, hair and muscles. - Limping gait
The word “claudication” comes from the Latin (meaning “to limp”), and the person often limps with the pain.
Signs
Chronic lower limb ischaemia presents with the following signs (examination findings):
- Cold, legs &/or feet which may be pale or blue (cyanosed).
- Reduced or absent pulses in the legs and/or feet.
- Dry, thin and brittle skin and nails.
- Loss of hair on legs and feet.
- Muscle wasting
- Positive Buerger’s sign
The above signs are a result of poor circulation and reduced nourishment to all the tissues with obvious changes, especially, to the skin; nails, hair and muscles.
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Amended April 2008
