Other common foot disorders and their management are described in Chapter 2.
The majority of patients will be asymptomatic and ischaemia will be diagnosed on screening examination. Patients with absent foot pulses should have their pressure index measured to confirm ischaemia and to provide a baseline, so that subsequent deterioration can be detected before the patient presents with irreversible lesions.
Podiatrists should always ascertain their patient's vascular status before they cut the toe nails or remove callus, since any injury to the neuroischaemic foot can result in ulceration.
All diabetic patients with evidence of peripheral vascular disease may benefit from antiplatelet agents: 75 mg aspirin daily, or if this cannot be tolerated, clopidogrel 75 mg daily.
Diabetic patients with peripheral vascular disease should also be given statin therapy.
The Heart Protection Study has shown that simvastatin reduced the rate of major vascular events in a wide range of high-risk patients including those with peripheral arterial disease or diabetes.
Patients who are above 55 years and have peripheral vascular disease should also benefit from an angiotensin-converting enzyme (ACE) inhibitor to prevent further vascular episodes (as indicated by the Heart Outcomes Prevention Evaluation (HOPE) and microHOPE study).
If symptoms do develop in the foot with ischaemia, there are three main clinical presentations:
• Intermittent claudication
• Severe chronic ischaemia with or without rest pain
• Acute ischaemia.
The classical site of claudication is the calf, although it may occur in the thigh and buttocks in aortoiliac disease. Claudication is less common in diabetic patients compared with non-diabetic patients because of peripheral neuropathy and the very distal site of atherosclerosis in the tibial vessels of the diabetic leg.
Patients with claudication should enter an exercise programme. All patients with claudication should be referred to the vascular surgeons but operative intervention is required in only 1% of diabetic patients per year. Pharmacological treatment with cilostazol can now be prescribed at a dosage of 100 mg twice daily.
Severe chronic ischaemia
With increasing severity of occlusive arterial disease, patients may develop a pink, painful pulseless foot (Fig. 3.9). The colour of the skin is a strikingly bright pink and the foot is cold.
The amount of pain will be related to the severity of the disease and the degree of peripheral neuropathy. When neuropathy is mild, patients will have classical rest pain, which is a constant pain, often worse at night and relieved by hanging the leg down outside the bed at night. It is important not to mistake the pink painful ischaemic foot for an infected cellulitic foot. The pink painful ischaemic foot is usually cool and the infected cellulitic foot is usually hot. If the leg is elevated the pinkness of ischaemia will fade while erythema of cellulitis will remain.
The pink painful ischaemic foot is an indication of severe arterial disease and urgent vascular investigations will be necessary with a view to vascular intervention. The pressure index will nearly always be less than 0.5, although medial calcification may give an erroneously high value. It is wise to proceed to further investigations including transcutaneous oxygen tension and toe pressure measurements. A level below 30 mmHg confirms severe ischaemia in both tests. Pain control is important. (For further discussion of these investigations, vascular intervention and pain control in the foot with severe ischaemia, see Chapter 4.)
Vascular intervention may not always be possible. If it is possible to control pain, then a trial of conservative treatment may be attempted instead of immediately performing a major amputation.
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