Clinical examination - arterial ulcers

In Figure 1, we have provided you with an easy-to-follow protocol for performing a standardized examination of a patient with arterial ulcers. Yes, it is a bit time-consuming, but examining in a standardized manner ensures that you will not forget to ask/check for essential things. Click on the image below, and it will open a pdf that you can print out and use in your clinic. This is your baseline, and can follow the patient’s chart during the entire treatment.  You obviously will not need to go through the whole protocol again at subsequent visits. Note that the ulcer/wound examination is at the end of the protocol.  You need to find out a lot about the patient before you jump to the inspection of the ulcer. Remember- do not just look at the hole in the patient; look at the whole patient! The evaluation of the wound follows the international TIMES model for wound assessment. We have written a separate chapter on this for more information on the TIMES acronym.

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Figure 1  A standardized protocol for the examination of patients with arterial ulcers. Click on the image above to go to a two-page pdf file that you can print out for your clinic.

Patient history  

If the patient with an ulcer on the leg or foot complains of pain in the legs when walking or even pain while resting, you should have a high suspicion of ischemia. Pain while resting indicates advanced atherosclerosis. Remember that patients with diabetic neuropathy may not feel any pain at all, even at advanced stages of atherosclerosis!  Again, always check new patients who have arterial ulcers for diabetes! We have ourselves gone into the trap of not checking this many times!  The worst situation is an arterial ulcer combined with blood sugar out of control. Remember that diabetes is one of the most common factors leading to atherosclerosis and subsequent inadequate circulation.

Before looking at the lower extremities and the ulcer itself, you should make a short patient history. The essential parts of the patient history are summarized in the suggested protocol above, and we will not repeat them here. However, we would like to stress the point of checking for anemia - i.e., checking the patient's blood hemoglobin levels which just a finger-prick blood test can quickly do, and checking for the HbA1c. Remember that anemia on top of poor arterial circulation will sabotage your attempts to get that wound to heal!  A Hb of < 10 g/dl will almost always give delayed healing, and a Hb <8 g/dl may cause the wound not to heal at all!  In many parts of Africa, where you do not have access to fancy reconstructive vascular procedures, you can at least try to improve the patient's hemoglobin levels! Remember also that the cause of the anemia may not always be easy to identify. If you find that your wound patient has low hemoglobin levels, you will have to start the detective work of trying to find the cause of the anemia. This usually involves doing more lab work to look for signs of iron deficiency and causes like chronic malaria, chronic hepatitis, and other infectious diseases.

Examination of the lower extremities 

When examining the lower extremities, start by looking at the skin condition.  Dry and hairless skin is typical of poor circulation ( atrophic skin).  The skin will often be pale with impaired circulation but may also appear more reddish!  In dark skin, these changes can be harder to detect. Poor circulation often also leads to changes in toenails - they become dystrophic, and many confuse this with nail fungus. However- fungus thrives in these dystrophic nails, so it can be challenging to distinguish dystrophy from fungal infection. 

Look for deformities in the foot which predispose to pressure-related injuries. Check the patient's footwear for sharp or hard edges. Prevention of pressure in these ulcers is just as crucial as it is with other pressure ulcers or diabetic ulcers!

Evaluation of the arterial circulation

The following are standard methods to assess arterial circulation.  Those highlighted in bold letters are the tests that can be done in a setting with limited resources.

 

  • Skin temperature

  • Capillary refill

  • Buerger's test

  • Palpating pulses

  • Pulse-oximetry

  • Ankle-brachial index

  • Toe pressure

  • Transcutaneous oxygen saturation

  • Colour duplex scan

  • Pulse-volume curves -plethysmograph

  • Radiological methods using contrast

We will briefly go through some of these tests:

Skin temperature

 

Evaluation of the skin temperature is probably the simplest method to detect inadequate arterial circulation. It is a test with relatively low specificity, so we have to interpret our findings with care. Use your hands to feel whether the extremities are colder to the touch than expected and feel after differences in temperature between the two lower extremities. Note that most patients have quite symmetrical atherosclerosis in both legs, so you may not detect a temperature difference! 

Many textbooks advise you to use the back of your hands to feel a temperature difference as this area of your skin tends to be more temperature-sensitive. This is not true for everybody - many colleagues say that they instead use the palms of their hands.  Some colleagues use both the back of their hands and the palms of their hands for this test. Obviously, If you use gloves, you will be less likely to detect subtle temperature differences. 

Figure 2 When you evaluate skin temperature, use your hands' back as they are usually more sensitive to temperature differences than your palms.

An infrared thermometer is a more exact method of measuring skin temperature. Even if you have limited resources available, we strongly advise you to try to purchase such a thermometer. It can also be a very useful tool for your clinic when examining other types of wounds!  If you do some searching online, you may get hold of such a thermometer for about 30 US dollars.  This is the same type of thermometer sold in most healthcare-related shops for measuring fever. However, we have tested a number of these thermometers. The one we found to give us the most consistent results is an infrared thermometer used to measure surface temperatures for industrial purposes! 

When measuring the skin's surface, the temperature recorded will not be the same as the body temperature - the surface of the skin is always some degrees cooler than the core temperature of the body. There is no standard surface temperature for our skin - this will be dependent on many factors. When using an infrared thermometer to assess blood circulation, we are interested in the differences in skin temperature - not the absolute values. For example, if we measure 32 degrees on the back of the right foot and 30 degrees on the back of the left foot, this could be a sign of decreased circulation in the left lower extremity. Again, using a thermometer to assess circulation is by no means an exact method. Still, it may be the most advanced option you have available in a workplace with limited resources. In the chapters on other wounds ( for example, diabetic foot), we will discuss other areas of wound care where such a thermometer can be helpful.

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Figure 3 Using an infrared digital thermometer can be valuable in assessing skin temperature. Note that the skin's surface temperature on the legs and feet will always be lower than the body's core temperature. There is no standard as to the average surface temperature of the skin on the legs and feet as this is quite individual and depends on many factors, including the room temperature and humidity. Investing in such a thermometer can also aid in diagnosing conditions other than reduced arterial circulation. In the picture above, we see the feet of a diabetic patient who had increased surface temperatures in the left foot due to an inflammatory condition called Charcot's foot.

Capillary refill

Have the patient lie down with the feet at about the heart level. Use your fingers to press with moderate pressure for at least 5 seconds on the foot ridge or over the nailbed of a toe. You will see a paler mark when you release the pressure and then count the seconds until the skin color has normalized. This usually takes 2-3 seconds in healthy individuals. If it takes longer, this can be a sign of impaired arterial circulation. Be aware that this is quite a simple test, and many pitfalls can mislead you. For example, patients with generally cold feet can have a positive capillary refill test without impaired circulation.  Edema of various causes, low blood pressure, and anemia can also mislead you. However, in combination with other tests, the result of the capillary refill test can give valuable clues.  If the capillary refill test is normal, the skin temperatures are unremarkable, and you find a normal ankle-brachial index ( see below), you can conclude with certainty that there is no critical impairment of the arterial circulation. Even though the capillary refill test has its limitations, we usually perform it since it gives us a rough idea of circulation status. It is also a useful test to check for differences between the left and right foot.

Figure 4 Capillary refill: Here, we pressed on the nail bed of the big toe for five seconds. Note the pale nailbed in the middle picture when the presure is released. Within 3 seconds, the nail bed had regained its normal color (right image).

Palpating the pulses of the foot 

You may choose to hop over the capillary refill test. However, it is essential to palpate the pulses of two easily accessible arteries of the foot.  Arteria dorsalis pedis runs on the back of the foot parallel to the extensor tendon of the big toe, and arteria tibialis posterior runs right behind the medial malleolus. As a rule of thumb, it is difficult to palpate a pulse in these arteries if the patient's systolic blood pressure is below 80mmHg. If you cannot detect a palpable pulse, this indicates that the pressure in the artery is lower than this level. 

Even if you have a doppler machine available, you should have a habit of always palpating the pulses with your fingers beforehand. This will make it easier for you to find the artery when placing the Doppler probe, and it will give you a clue about what to expect. As a rule of thumb- if you can palpate the arterial pulse with your finger, the circulation is usually " not too bad." 

Figure 5  Landmarks for finding the relevant arteries in the foot. Left: Arteria dorsalis pedis ( red dotted line) runs parallel to the extensor tendon of the big toe. Right: Arteria tibialis posterior runs approximately a fingers width behind the medial malleolus 

Ankle-Brachial Index (ABI)

Measuring the ankle-brachial index is an important test to evaluate the severity of the circulation impairment and whether the patient requires more advanced treatment. The method is easy to learn and requires only a blood pressure cuff and a handheld vascular doppler machine.  The price for a vascular doppler lies from 200 US dollars upwards, and understandably only a few health personnel in Africa have access to this. Since an ABI evaluation is also very important for venous- and diabetic ulcers, we have written a separate chapter for ABI.  Here we also come with some suggestions for workarounds when you don't have access to a vascular doppler. Did you know, for example, that you can use a stethoscope and a blood-pressure cuff to try to measure the ankle-brachial index? You can also try to use a pulse-oximeter on the big toe if you don't have a doppler available, but this method is more prone to error.  Click on the picture below to go to this chapter.

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Figure 6  You can measure the ankle-brachial index with a handheld vascular doppler ( right) or with a fully automatic machine with several cuffs (left). Understandably many health personnel in Africa won't have access to this kind of equipment. We have written a more detailed chapter on ABI. Here we also provide some work-around solutions when you don't have access to this type of apparatus.  Click on the picture above to get to this chapter. 

Other non-invasive methods

There are many other methods to measure arterial circulation. This can involve, for example, transcutaneous oxygen measurements, color duplex scanning, systolic toe pressure, or pulse-volume curves from a plethysmograph.  These tests require more sophisticated equipment and are usually done at more advanced clinics. We will, therefore, not go into more detail here. 

Using contrast to check the arterial circulation

To find out where the stenotic passages are in an artery, we have to perform a radiological examination using contrast injected into the arteries - an angiogram.  This can be performed with conventional X-rays, but most clinics today use CT or MRI machines.  The contrast is injected into the arteries, and pictures are taken in fast sequences. Care has to be taken with patients with renal insufficiency when using contrast as this may worsen the renal function. These patients have to take blood tests beforehand to check their creatinine levels and the glomerular filtration rate (GFR). Keep in mind that many patients with atherosclerosis in the lower extremities also have renal insufficiency. Patients with impaired renal function may have to get fluid therapy before and after a vascular examination using contrast. Another possibility is a selective angiogram where only the affected lower extremity is injected with contrast, thereby needing lower amounts of contrast agent (kidney sparing dose).  If an MRI machine is available, it is preferable to do an angiogram there. This technique uses a different type of contrast which is tolerated better by the kidneys.

Note that there also are interactions between contrast and other medications. The radiological department will, for example, require information on whether the patient is using metformin - an oral antidiabetic agent.  Suppose a patient is receiving iodinated contrast and experiences renal failure. In that case, medication with metformin can lead to a toxic accumulation of the drug leading to lactic acidosis - a severe condition. Many x-ray departments demand metformin be withheld for 48 hours after the contrast agent is administered to avoid this complication. If renal function is normal at 48 hours, the metformin can be restarted.

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Figure 7 Using contrast injected into the blood vessels, it is possible to visualize the locations of stenotic passages in the arteries. This technique is called an angiogram.  This can be done using conventional x-rays or, more commonly, CT or MRI techniques. In this example, we saw decreased circulation starting in the left thigh area.