Chronic Limb Ischaemia

Procedure

Patient rests lying down for 5–10 minutes. Using a blood-pressure cuff and hand-held Doppler, measure the systolic pressure in both arms and at both ankles. For each leg, divide the higher ankle pressure by the higher arm pressure.

Positive Finding

An ABPI of 0.90 or below; much lower values with severe disease. A very high reading means stiff arteries and an unreliable result.

Sensitivity / Specificity

Interpretation

Confirms arterial disease and gives a rough guide to severity. In people with diabetes, stiff arteries can give a falsely normal reading, so toe pressures are more reliable. Rest pain, ulcers or gangrene with a low ABPI mean chronic limb-threatening ischaemia and need urgent vascular referral. From a 2010 review of 8 studies with 2,043 patients or legs (Xu et al.; abstract read), for an ABI of 0.90 or below against 50% or more narrowing on imaging. Sensitivity varied widely and was lowest in older people and in people with diabetes, whose stiff arteries can give falsely normal readings, so a normal ABI does not rule arterial disease out in these groups. The review reported specificity of 83–99%, but who made up the comparison groups could not be checked from the abstract, so specificity is not shown. The 95% / 100% previously stored was not supported.

Procedure

Ask the patient to walk at a steady pace on a flat surface (or a treadmill in a vascular laboratory). Record the distance at which leg pain starts and the distance at which they have to stop.

Positive Finding

Cramping or aching in the calf, thigh or buttock that comes on with walking, at a similar distance each time, and eases within a few minutes of standing still.

Interpretation

Describes how severe the claudication is and gives a baseline to track change. Pain in the foot at rest, especially at night and eased by hanging the leg out of bed, or ulcers or gangrene, mean chronic limb-threatening ischaemia: urgent vascular referral. Pain eased only by sitting or bending forward suggests neurogenic claudication from spinal stenosis instead. This measures how far the patient can walk before leg pain starts. It is used to grade severity and track change over time, not to diagnose arterial disease, so no accuracy figure applies. The figures previously stored here could not be matched to a study.

Procedure

Press on the pad of a toe until the skin goes pale, hold for about 10 seconds, release, and count the seconds until the normal colour returns. Compare with the other foot.

Positive Finding

Colour takes 3 seconds or longer to return (normal is under 3 seconds), or clearly longer than on the other foot.

Interpretation

Unhelpful for deciding whether arterial disease is present, and affected by room temperature. Use pulses, venous filling time and ABPI instead. A 1998 review of the physical examination for chronic leg ischaemia (McGee & Boyko) found the capillary refill test unhelpful for diagnosis, and a study of 631 people with diabetes (Boyko 1997) found a refill time over 5 seconds gave little diagnostic information. No figure is shown.

Procedure

Patient lying on their back. Raise both legs to about 45° for 1–2 minutes and watch the soles of the feet. Then sit the patient up with the legs hanging over the edge of the bed and watch the colour return.

Positive Finding

The sole turns pale when raised, then turns a dusky red (dependent rubor) when the legs hang down.

Interpretation

Suggests severe chronic arterial disease with a poor blood supply to the skin. The lower the angle at which the foot turns pale (Buerger's angle), the more severe the disease. Dependent rubor, rest pain or tissue loss need urgent vascular referral. A 1998 review (McGee & Boyko; abstract read) found Buerger's test helps judge how severe and widespread arterial disease is, rather than whether it is present. Its figures are in the full text, which has not been read, so no figure is shown.

Procedure

Listen with a hand-held Doppler over the femoral, popliteal, posterior tibial and dorsalis pedis arteries, or record the waveform in a vascular laboratory.

Positive Finding

Loss of the normal multi-part signal: a single dull (monophasic) signal, or no signal at all.

Interpretation

A healthy leg artery gives a crisp two- or three-part sound. A single dull sound suggests narrowing above that point, and the level at which the signal changes helps locate the disease. Needs training; findings are confirmed with ABPI or duplex.

Procedure

Vascular laboratory test. A heated sensor on the skin of the foot measures how much oxygen reaches the skin over 10–20 minutes.

Positive Finding

A low oxygen level on the foot compared with a reference site.

Interpretation

Used by vascular teams to judge whether a wound or amputation site is likely to heal, especially where stiff arteries make pressure readings unreliable. Affected by swelling, skin thickness and temperature. Not a test for osteopathic practice.