Dr Chua Soo Yeng Benjamin
The moment patients lose a limb, they notice a significant decrease in the quality of life. With the loss of mobility, they find it hard to keep their jobs. Many not only become depressed but also because they spend most of their time in bed or are wheelchair-bound, they are prone to pneumonia and pressure sores.
But it's not just the patients who suffer. There are significant physical, emotional and financial strains on family members and caregivers as patients require constant support, nursing and medical care. Therefore, every effort must be made to preserve the limbs of diabetics with Peripheral Arterial Disease (PAD), thus saving their lives.
Peripheral Arterial Disease is the narrowing or blockage of the lower limb arteries, resulting in diminished blood flow to the legs. These arteries are responsible for carrying oxygen- and nutrient-rich blood to the muscles and tissues of the lower limbs.
PAD is especially prevalent in diabetic patients who have poor or suboptimal blood glucose control. This is further aggravated if patients also have poorly controlled blood cholesterol levels or continue to smoke cigarettes.
Aside from diabetes, other risk factors include chronic smoking, hypertension and end-stage renal failure.
The simplest screening test is a clinical examination to determine the presence of foot pulses. Another simple bedside clinical test, known as the Ankle-Brachial Pressure Index (ABPI), can be used to quantify the severity of PAD. This involves taking the systolic blood pressure in the legs and comparing to that of the arms.
Once PAD is diagnosed, additional ultrasound or CT scans of the lower limb arteries can help determine which parts of the arteries are diseased so as to plan for surgery.
We classify patients with PAD into 2 broad groups according to symptoms and signs.
Those in the intermittent claudication group are patients experiencing severe cramping pain in the affected segment of the lower limb (ie. thigh, calf or foot) that develops on walking or exercise.
This severe cramping pain usually sets in after a repeated, fixed distance of walking or duration of exercise and is relieved by simply standing still. If left untreated, these patients may gradually find that they can no longer walk or exercise for long without pain. As a result, many of these patients find themselves limiting their mobility to avoid the pain.
The second group comprises patients who progress from intermittent claudication to pain even at rest, especially when lying down. They may also notice that the affected lower limb is cold and pale. Some of these patients may go on to develop non-healing foot ulcers or whose toes or foot lose body tissues as a result of loss of blood supply. They may develop life-threatening systemic sepsis – a condition where chemicals released into the bloodstream to fight infections cause widespread inflammation instead – as a result.
Other signs of progression of PAD include absent limb pulses and pus discharge from the wounds. These patients require very urgent treatment as they have a significant risk of undergoing major below-knee or above-knee amputations resulting in limb loss.
There are 3 ways to prevent major lower limb amputations.
Medical therapy consists of monitoring risk factors, exercise training, early treatment of wound infections and the use of anti-platelet drugs. It usually works well for patients with mild or moderate PAD.
Monitoring Risk Factors
The aim is for patients to achieve optimal blood glucose, cholesterol and blood pressure levels. This can be achieved by taking the correct types of medication in the right doses to control these risk factors.
Patients are also started on anti-platelet drug therapy to reduce the risk of developing a heart attack or stroke.
This involves getting patients to continue walking despite the pain. The aim is to encourage smaller arteries to enlarge so as to supplement new blood supply to the limb muscles.
When wound infections are detected early, antibiotics can be prescribed accordingly. Infected tissues are removed while taking care to preserve a functional lower limb and foot. Major amputations are avoided unless absolutely required.
After removing the infected tissues, a wide range of techniques are available to care for the resultant wound. If it is large, skin may be taken from other parts of the body to cover the wounds. This process then allows the patient to regain their mobility and resume their activities of daily living.
Your doctor might recommend surgery if your condition does not respond well to medical treatment or if your condition is too severe to be coped with the medical treatment alone.
More and more patients are offered minimally invasive procedures – angioplasty and stenting.
The angioplasty procedure is done under local anaesthesia and light sedation. A wire is inserted through an artery – sometimes in the groin, sometimes in the foot – and guides the angioplasty balloon to the affected segment so as to re-open or widen the artery again.
Special metal stents are then used to keep the arteries open after the initial angioplasties in order to prevent repeat narrowing or blockage.
In open bypass surgery, the surgeon uses the patient's lower limb vein as a channel to bypass the blocked artery. The vessel is sewn above and below the blocked artery so that blood flows through the new vessel instead. Sometimes, an artificial blood vessel graft is used in place of the patient's own vein if the surgeon cannot find a suitable vein to use.
Pros: Angioplasty and stenting significantly reduces the patient's risk of disease progression and death. Multiple target arteries can be treated in a single setting as opposed to open surgery. There is a shorter recovery period and patients can be discharged earlier than those who undergo open bypass surgery.
Cons: The treated artery will eventually re-narrow after approximately 2 years. Patients may require repeated angioplasty procedures to keep the arteries open on a long-term basis.
Pros: Open bypass surgery is effective and its effects are long-lasting. It is similar to starting a new highway where the road is clear for blood to flow.
Cons: Open bypass surgery candidates have to be medically fit to undergo the surgery and accept long incisions. Recovery from open bypass surgery can be slow because of the painful incision wounds.
Early intervention for diabetics with PAD is crucial in ensuring patients retain mobility. The rapidly improving techniques and technology now offer most patients a lower risk solution to saving their lower limbs. When combined with advanced wound care techniques, patients whose options for limb salvage were once limited can now look forward to avoiding limb loss.