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Diabetic Foot Tests

AB Index/Ankle Brachial Index

Even though the term sounds complicated, this is a simple test to know about the vascular supply to the lower limbs. Elevated blood glucose levels in diabetics causes abnormal variation in the endothelial cells, which is the inner layer of blood vessels. This causes obstructions of the blood vessels leading to decreased blood supply. It affects the blood vessels of lower limb, the condition is known as peripheral vascular disease. It is commonly seen in chronic smokers. A non-healing ulcer and gangrene is mainly due to de-creased blood supply to the lower limbs caused by peripheral vascular disease. Pain and fatigue to muscles in the leg after walking a small distance are the primary symptoms of this disease. This is relieved by taking rest and the patient will be able to walk again after some time.

These symptoms will not be present in all diabetics. In AB index/Ankle brachial index we look for the ratio between the blood pressure of upper limbs and lower limbs. In order to get an accurate blood pressure measurement we use a small Doppler for this purpose. Normally there is not much difference in the blood pressure of both upper and lower limbs. AB index between 0.9 to1.3 indicates normal blood vessels. If it is less than 0.9, can be assumed that there is decreased blood supply. Some patients have ABI more than 1.3. This does not mean that there is more blood supply. Deposition of calcium ions in the walls of blood vessels leads to thickening, which causes an apparent increase of blood pressure. Some sophisticated methods are needed to measure the blood supply to the legs in these people.

As decreased blood supply to lower limbs put one at risk for to diabetic foot problems, it is worthwhile to have yearly check up to diagnose peripheral Vascular Disease as early as possible.

Biothesiometry

The term Biothesiometry may sound very unfamiliar to many diabetic patients. You would know about it only if you are attending a well-equipped modern diabetic department for your diabetic care. This is a test to assess the sensation of the foot. Neuropathy is one of the commonest diabetic complications. From the skin, nerves carry the sensations like touch, pain, vibration, pressure, heat or cold to the brain. We feel these sensations only when it reaches specialized areas of brain concerned specialized areas of brain concerned with perception of sensation. When these nerves are damaged by uncontrolled diabetes, it causing tingling and numbness of feet which later on become numb.This loss of sensation of feet makes them very susceptible to injury. These trivial injuries usually lead to severe foot problems.

Hence assessment of sensation. This can be done by a simple tuning fork tests which assess the vibration sensation. But this test cannot differentiate between the severities of loss of sensation. Biothesiometer is an instrument which can be made to vibrate at different frequencies. While testing, the probe is placed on patient’s toe and frequency is gradually increased up to the level where patients feel it, and that frequency is taken as vibration perception threshold. If the threshold is 15 or less, it is said to be normal. 15 to 20 is said to have mild neuropathy. 20 to 25 is moderate neuropathy and above 25 is considered as severe neuropathy. Patients with severe neuropathy are found to be at high risk of developing foot problems. If this test done yearly, you can also assess whether neuropathy is progressing or not. If patients with high grade neuropathy can be educated properly about diabetic foot care, serious foot injuries can be prevented. Biothesimeter forms an important tool for the sensory assessment of foot.

Monofilament Test

Monofilament testing is commonly used worldwide for the detection of diabetic peripheral neuropathy. This is a very simple and inexpensive method used for the detection of diabetic neuropathy.

The advantage of monofilament testing is that it provides clear, quantified, and repeatable information about the patient’s ability to recognize the sensing of touch.

The test is performed with a monofilament, which, despite of having a very small diameter possesses an incredible strength, is pressed against various parts of the foot and the patient should be able to feel the pressure as well as to identify the correct site. When applied straightly, this will apply 10 g pressure on the surface of the skin and if the patient recognizes the pressure applied and wherever it is pressed on his foot, then it is a sign that the foot has not lost protective sensation i.e., it can still feel pain and thereby ensure to avoid getting injuries.

On many occasion, the, patient may not sense the force pressure applied on some part of the foot or on the complete foot. Owing to this insensate condition there are plenty of chances to get injuries on these feet and because of this it is compulsory that the patient must use therapeutic footwear in order to avoid getting hurt. This prevention method will eliminate the conditions that eventually lead to amputations of the foot. Thus, it is always advisable for diabetic people to get the monofilament test also done along with the tests done for identifying neuropathy.

Pedopodograph

Pedopodograph consists of a plate which has highly sensitive sensors embedded in it. Patient is asked to stand and walk on it. The machine detects the pressure exerted on different areas of food and gives an image of this. The sensitivity and accuracy of podograph depends on the number of sensors per sq. cm. These vary from 1to 5. The other parameter that determines the sensitivity and accuracy of podograph is frequency at which the sensors transmit the information. This varies from 60MHz to 500MHz. Higher the frequency, the more accurate and sensitive is the podograph.

The plate is connected to a box with special software by a cable. The software in the box processes the information collected by the sensors and transmits it to the computer in the form of dynamic 2D/3D images. The areas of highest pressure are shown as yellow color. Moderately high pressure is denoted by green color. Normal pressure is shown with blue color. In addition the software measures the pressure in either Newton/cm2 or Kpa(Kilopascals). These are units of pressure measurement. The images also show foot deformities, axis of walking, change in the in the shape of the foot, walking pattern. Much scientific information is generated by the software in the form of graphs, charts, figures etc. The scan also gives the model/ prescription of Orthotic support. The pe-dopodograph can detect areas of high pressure developing in a diabetic patient’s feet 12-18 months before the development of callus. Once the callus is formed, the thickness of skin in these areas can be detected either by hand or naked eyes. This test has to be used in conjunction with other neuropathy assessments tests.

Anodyne Therapy

The word Anodyne comes from Latin and means without (ano) pain (dynus). Anodyne Therapy is a patented form of Monochromatic InfraRed Photo-Thermal Energy.

What is an Anodyne?

Anodyne is a therapeutic device that delivers monochromatic near infrared photo energy through light emitting diodes (LEDS) in contact with the skin. The light is emitted by an array of 60 super luminous Gallium Aluminum Arsinide diodes located on flexible pads, 4 1/4" by 2 1/4" (22 square inches). Monochromatic means that the light emitted is within one specific wavelength, namely 890 nanometers. 890 nm was chosen because of the depth of penetration and high absorption because photo energy to be effective must be absorbed by the target tissue (Fig 1). Since the photo energy (light) is infrared, it cannot be seen. The Anodyne Therapy System is a Class II, non-invasive medical device cleared for marketing by the FDA in 1994 for increasing circulation and reducing pain. The Anodyne device is covered under US Patent Number 5,358,503. Anodyne Therapy is safe and meets the Photo-Biological Emissions guidelines for eye and other body tissues.

The average energy emitted from the diodes is 9 milliwatts per square centimeter. The density of the photo energy emitted per pad dining a 30-minute treatment is 43.2 Joule/cm. Thus Photo-thermal Energy shall be 1020 mw per array and 8160 mw (8 array)

What happens when the Anodyne unit is used?

Thediode array creates a comforting warm feeling under the pads. The photo energy (pad heat) dilates the blood under the vessels increasing circulation. The light (and heat) also reduces pain. Additionally, patients experience a decrease in local swelling, decreased inflammation, decreased muscle spasm, decreased tension and muscle tightness, increased range of motion, increased lymphatic drainage and increased venous dilation and flow. Diabetic patients with peripheral neuropathy typically experience an increase in sensation to pressure and hot/cold.

How does Anodyne reduce pain and increase circulation?

The photo energy releases nitric oxide from the hemoglobin and possibly surrounding tissue. Nitric oxide is a signaling molecule that is known to relax smooth muscle cells in the arteries, veins, capillaries and lymph vessels. When these muscles relax, they dilate the blood vessel, thus allowing increased circulation. Nitric oxide has been shown to be essential for wound healing even if chronic or traumatic. Scientific literature shows that nitric oxide promotes collagen synthesis, collagen fibril alignment, and angiogenesis. Nitric oxide is also a neurotransmitter.

Have increases in circulation associated with Anodyne ever been measured?

Tests have been conducted with a scanning laser Doppler, which measures circulation at 1 to 2 millimeters (micro-circulation). These tests demonstrate increases from 400% to 3200% after a 30 minute Anodyne treatment. Please note that comparative increases in circulation using heat or ultra sound are substantially less than those observed with Anodyne.

Indications

Anodyne therapy is cleared by FDA for increasing circulation and reducing pain, stiffness and muscle spasm. Clinical applications include treatment of: acute pain/ injuries, muscle spasm, stiffness and pain and or poor circulation caused by chemotherapy, diabetes, vascular diseases, etc. Anodyne Therapy may be used over or near any part of the body - including the spine, Metal implants, plates, pins and screws, Pacemakers, Defibrillators.

Contraindications

Anodyne Therapy may NOT be used over or near active cancerous tumors, womb during pregnancy, Topical heating or cooling agents, or their residuals. Pain patches, or their residuals. Does not use near an active malignancy? Do not use in patients who are pregnant. Limb or area under therapy should not be wet, as it can lead to burns. Diabetic patients should closely monitor their insulin levels during treatment as some patients require less insulin and may need to adjust their insulin dosage to prevent hypoglycemia.

Duration of Therapy-Regimes

Safety and Precautions

Anodyne Therapy may be used over or near,

Any part of the body - including the spine, Metal implants, plates, pins and screws, pacemakers, Defibrillators.

Active cancerous tumors, The womb during pregnancy, Topical heating or cooling agents, or their residuals, Pain patches, or their residuals. Anodyne Therapy is an infrared-thermal modality, and thus, there is a slight risk of a superficial burn

Benefits and uses

HCP Sensitometer

Have you ever wondered, how a diabetic patient can walk without limping when he has an ulcer on the foot?

Have you ever wondered how a diabetic patient can walk barefoot in a hot sunny day-on a pilgrimage?

We have come across patients who have dipped their feet in hot boiling water, applied heated iron box over their feet for relief of pain and ultimately landed up with an ulcer. This is due to the loss of pain, pressure and touch in diabetic patients feet due to neuropathy.

The 2 main risk factors are,

The nerves when damaged due to Diabetes can affect the,

These individual group of nerves can be affected separately or together giving rise to various symptoms of neuropathy like burning feet, tingling numbness; feeling of walking in air, change in shape of foot, dry crack feet etc; Damage to sensory nerves leads to sensory neuropathy, which in turn can lead to loss of sensation like touch/pain/pressure/vibration/heat and cold.

It is said that amongst the peripheral sensations (heat/cold/light touch/pressure/vibration) the earliest sign of peripheral neuropathy is loss of heat/cold sensation. In a normal person a temperature of 25 degree c or sometimes even<20 degree c. Similarly a normal person would feel warmth at around 38 degree c. In a patient with neuropathy they are however, unable to feel temperature even at 40 degree or even > 48 degree c and these patients are diagnosed to have neuropathy (SF).

A precise quantifiable system of sensory testing is needed for diabetic patients. Hence the large and small fibres should be evaluated and tested separately. The simplest way to test the large fibre is the monofilament test which can be even taught to the patient. However, a quantifiable test for large fibre neuropathy is the biothesiometer which was already explained in the previous issue of diabeat.

The next group of sensory neuropathy are the small fibre neuropathy are the small fibre neuropathy which is usually diagnosed by exclusion, ie, if the standard sensory neurological examination is normal and patient still complains of pain, or the neuropathy quantified is less severe compared to complaints. Such patients are labeled, to be having small fibre neuropathy.

So these group patients who complained of typical neuropathic pain, but standard investigations of sensory neuropathy are found to be normal, such patients were earlier treated empirically as small fibre neuropathy. However, now we would like to introduce the state of art equipment at our institution THE HEAT AND COLD SENSITOMETER which can detect the earliest signs of small fibre sensory neuropathy, and also quantify the same.

This instrument not only detects neuropathy but also grade it as mild/moderate/severe and also we are able to monitor the progression of disease process on every visit.