Case Study

Severe ischaemia

A 57-year-old man with type 2 diabetes of 7 years' duration underwent right femoral popliteal bypass. Eleven years later he flew to Canada. During the return flight he developed pain and numbness in his right foot and leg. He visited his local casualty department. A diagnosis of ischaemia was made but the severity was not appreciated and the patient was sent home. Next day he came to the diabetic foot clinic. The foot and lower leg were bright pink, icy cold and pulseless, with swollen toes and severe pain around the 1st metatarsophalangeal joint. Doppler studies could not detect pulsatile flow in the foot, and transcutaneous oxygen tension was 3 mmHg in the right foot and 50 mmHg in the left foot. He underwent an angiogram which showed that the graft was not patent. Further vascular intervention was not possible.

He developed necrosis on the medial aspect of the 1st metatarsophalangeal joint, and the lateral border of the foot. He also developed severe rest pain which was controlled with morphine sulphate. He refused a major amputation, and elected to undergo conservative treatment of his ischaemic foot in the diabetic foot clinic. There was a slow but gradual improvement leading to complete healing of the foot after 4 years. However, during this time he had five further admissions for infections. He had an initial period of 5 months off work but was then able to remain in full-time work. Ten years later he still has two legs.

Key points

• Severely ischaemic feet in the diabetic patient may be difficult to diagnose because rest pain may not be as severe as in non-diabetic patients without neuropathy

• Severely ischaemic feet can sometimes survive without revascularization

• Close follow-up care from a multidisciplinary diabetic foot clinic is essential

• Healing can take years.

Acute ischaemia

A sudden occlusion of a major artery, usually popliteal or superficial femoral, will result in a pale, painful cold foot with purplish mottling. Initially the skin is intact, but if treatment is delayed digital necrosis will develop. (Management of necrosis is described in Chapter 6.)

Acute ischaemia is a rare complication of the stage 2 diabetic foot and can present very suddenly in:

• Patients with no previous history of vascular problems

• Patients with a history of steadily deteriorating chronic ischaemia

• Patients who have previously had peripheral arterial bypass which occludes or angioplasty with recurrence of stenosis or occlusion.

Unless the patient is profoundly neuropathic he will complain of sudden onset of pain in the leg and foot. If a hand is run down the leg a 'cut-off' point will be found where the temperature of the skin suddenly decreases. Symptoms may include:

• Paraesthesiae

• Blueish-grey discolouration with mottling or 'bruised' appearance

Acute ischaemia is a clinical emergency associated with severe morbidity and mortality. If the leg is to be saved it is necessary to reperfuse it as a matter of urgency. Immediate vascular intervention is needed.

Metabolic control

Even though neuropathy or ischaemia may now be present, progression may be checked by tight control of blood glucose, blood pressure and blood lipids, and stopping smoking.

Swelling may complicate both the neuropathic and the neuroischaemic foot and it is an important factor predisposing to ulceration. Its main cause will be impaired cardiac and renal function which should be investigated and then treated accordingly. With deteriorating renal function swelling of the feet becomes a crucial factor leading to the intractable ulceration of end-stage renal failure. (See Chapter 6.)

When patients go on to haemodialysis the swelling can vary throughout the week according to the time of dialysis and it is important for the footwear to be adjustable, to accommodate fluctuant swelling.

Venous insufficiency can cause swelling of the leg and foot and should be investigated with duplex scanning, treated with support hose and referred for a vascular opinion as to the need for vein surgery.

Neuropathic oedema may respond to ephedrine starting at a dose of 10 mg tds but this may need to be increased up to 30-60 mg tds.

Educational control

General principles

• 'One-to-one' education can be carried out during the routine appointment by the podiatrist while the feet are treated

• 'Little and often' is the rule. When long 'lectures' are delivered, patients 'switch off'!

• Always seize the opportunity to get a point across or to ask a question which might reveal danger. Patients who volunteer that their vision is poor will need help with the foot check

• Changes in the patient's lifestyle (an impending holiday or trip, or a change of occupation) may indicate the need for extra education

• The diabetic foot service should get to know their patients well and be aware of changes going on in their lives which might have adverse effects on their feet

• Education programmes should be flexible, sensitive and individualized

• All stage 2 patients should be taught the danger signs of actual or impending foot problems and should know what to do and where to go to get rapid help, as described for stage 1 patients.

Above all, it is important to educate stage 2 patients in trauma prevention programmes so as to avoid ulceration and entering stage 3.

Psychological factors should also be specifically addressed in stage 2 patients.

Trauma prevention programmes

Trauma is the precursor of many ulcers, fractures and Charcot's osteoarthropathy. A special trauma prevention programme is needed for the successful management of stage 2 patients.

Causes of trauma

• Wearing of unsuitable footwear which rubs blisters and sores

• Wearing of'thong'sandals

• Walking barefoot

• Foreign bodies within the footwear (patients should be taught to shake out their shoes before donning them and to check the inside for rough places or ruckled insoles). One of our patients developed severe ulceration when her small son dropped a Lego brick into her shoe: we found the brick later, deep within an ulcer!

• Nail penetration: one patient travelled from India back to England bringing back a tintack deeply embedded in his foot

• Burns from hot bath and shower water. Patients should check temperature of water with elbow or bath thermometer

• 'Toasting toes' in front of fires or fan heaters

• Falling asleep in front of the fire

• Spilling boiling water

• Falling asleep on the beach (sunburn)

• Frostbite. One of our patients suffered frostbite after being found lying unconscious in the snow.

Another patient with frostbite was a butcher with profound neuropathy who worked within a deep freeze room.

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