Facing the Challenges of PAD and CLI in Diabetic Foot Disease

Editor's Note: Please note that at minute 2:55 in the video, the speaker acknowledges a verbal error. His statement is that "less than half ... knew their patient had PAD," not diabetes.

My name is John Evans. I'm a podiatrist practicing in Southeast Michigan. I'm certified by the American Board of Foot and Ankle Surgery, in foot and ankle, and also by the American Board of Podiatric Medicine. I have been practicing for over 35 years, and basically private practice right now. I'm the chief of podiatry at Beaumont Hospital in Michigan. I am a member of the Health Policy and Practice Committee, presently as the past chair for the organization. I'm very active with Medicare issues, having served as the carrier advisory committee representative for over 20 years. And presently, I'm the podiatric representative to the Guidelines Committee for Peripheral Arterial Disease for the American Heart Association and the American College of Cardiology.

Well, there's a number, and some of them aren't specific to the diabetic foot, but are within PAD in general. And one of the first and foremost is awareness, one by the public. The public is not very aware of what's going on, and this is specifically important when it comes to the diabetic public. The American Diabetes Association did a survey earlier this year of about 3000 patients who had diabetes. And while they answered that over 50% of them knew that diabetes was a risk for amputation, less than a quarter of them thought they would fall into that category of possibly needing an amputation. And only about 15% of them knew anything about the more severe stages of PAD, such as critical limb ischemia or chronic limb threatening ischemia. So the public's not aware of it. Besides that, it doesn't have very good PR. Really on studies of the general public, only around 20% of patients really have an understanding of what PAD is.

But even worse are professionals like ourselves. There often is a lack of knowledge and understanding of that. A study was done earlier in the century where they looked at primary care physicians who were treating diabetics, and less than half of them were aware that their patient had [PAD - see erratum above]. So the next problem is being aware that the patient may have symptoms of PAD. It doesn't always jump out at you. Now, most of us are pretty good about picking it up if someone comes in with signs of significant ischemia, if they're having classic claudication symptoms of exertional pain in one of the lower extremity muscles, or if they come in with a non-healing wound or gangrene. But to reach that stage, the PAD has to be fairly advanced. And again, studies have shown that often, less than 15% of the patients show up with signs of classic claudication. So if the physician is waiting for these symptoms to occur, they're going to miss up to 90% of their patients who have PAD. And if they're not aware of it's certainly not going to get treated.

So we have these patients who have multiple comorbidities, specifically any of the cardiovascular issues, heart disease, hypertension, atrial fibrillation, if they've had some ischemic problems with the brain, TIAs or strokes, if they have renal disease, we see a significant increase in PAD, if a patient is a smoker. These are all risk factors for it. So one of the important things as a clinician we need to do, is to be aware of the patient's past medical history. And quite honestly, primary care is bad at this, but even my own colleagues and myself at times don't pay attention to the comorbidities when we're looking at the patient's past history or we're looking at their medications and realize that this patient is on lipid lowering therapy and they're on hypertensive medications. Or they're on medications that treat heart failure along with diabetes and such. So it's easy for us to miss these things, even if in retrospect, it's kind of easy to tell.

So the next problem is diagnosing it. If we presume the patient may have diabetes, there are some simple diagnostic tests we can do. The one that is most commonly done and the one that has shown the best overall ability to point out some level of disease is the ankle-brachial index. It's inexpensive, it's simple to do, staff can be trained to do it, and it works a lot of the time. So we know that the ratio of the compressibility of the vessels in the ankle is divided by that of the arm, just your traditional blood pressures. Then you come out with a ratio. Normal would be 1.0, whether it be relatively equal, or that the pressure in the leg might be a little bit higher. So anywhere from 1.0 to 1.3 or 1.4 are considered within a relatively normal range and above 1.4 would be considered PAD, the vessels aren't compressible. And if the ABI is less than 0.9, we consider that PAD. But we got a range that goes on in there.

If a patient has vessels that are difficult to compress like those in diabetes or with renal disease, we can't trust the ABI. We have to look for other things. So you need to have some degree of suspicion when you're dealing with this. Now, fortunately, there are some other testing that can be done. Exercise ABIs are good for helping to pick out patients who may have PAD. Your [inaudible 00:07:07]-brachial index is quite useful because the vessels in the digits don't tend to be affected as the calcification as much as those larger vessels in the leg. So it can point it out better like that. But still as you can see, you're depending on the compressibility factor to go this way. We also have tcpO2s. We have skin perfusion therapy. These are great because basically, it doesn't really matter whether there's good pulses or not if the tissue is not getting oxygenated, which has a lot to do with micro circulation, which we have a very difficult way of measuring.

And up until recently, we really didn't have any functional ways of doing it. Now, fortunately now we do. We've got two devices on the market, your spatial frequency domain imaging devices, and your near infrared spectroscopy. Now, both of these are commercially available and can be useful to determine the hemoglobin and oxygen concentration of the dermis. And basically that's what we're looking for, to get an idea if the oxygen's actually getting down there. But again, the technology's available, but only a small percentage of practices actually have it to be utilized, so that's difficult.

The next problem is we have a disease state that's progressive. It gets worse from the time you are born until the time you die. And even if you treat it, it's still there. So we're us who are surgeons in the foot and ankle, if we fuse an ankle, if we fix a bunion, it's fixed. But with PAD, it's different. These people who require an intervention, even after they have the intervention, the risk of them having a future ischemic event, which we call major adverse limb events, which is an ischemic condition that requires some sort of intervention, either surgical or interventional or bypass or amputation, that the limb will not survive. Even the idea of having the best medical treatment in the world with the best interventional procedure, even after that, the risk of having a future adverse limb event goes up four times, and it does this almost immediately after the procedure.

So people who have interventions do it because they really need it. But even that one idea that they had, it increases the risk of them having future problems. Now, the benefit is if they had a successful procedure, the arteries open. With any luck, you've saved the limb. But it doesn't mean that not for the rest of their life they have to be concerned about this. And majority of patients, and even a lot of clinicians who aren't vascular trained, really don't realize that they're not fixed. They need to be watched for the rest of their life. And who is going to do the watching? Most of it's going to be through podiatry because that's what we do. We are going to see patients 1, 2, 6 times a year, and we need to be watching for it. So any of our patients that go out for interventions, we need to be aware that it's not fixed. And unfortunately, a lot of our colleagues and primary care really aren't aware of this.

So we have this technology to do all these incredible interventions. We have this great technology to be able to diagnose the problem. We've even gotten better treatments at it. We've been shown that lipid lowering therapy has a huge effect on the development of the atherosclerotic process, not just in the legs, but also around the heart, the coronaries and the renal arteries. We have this technology that can help diagnose it. We have new medication therapies that help to treat this with the whole development of the concept of dual pathway inhibition, in which we treat this atherosclerotic and atherothrombotic issue with antiplatelet medication along with anticoagulant medication. And since we have a group of medications now that are the direct oral anticoagulants, they've been shown to be much more effective and safer than the previous ones we had, which were basically warfarin. And so we have one medication now, rivaroxaban, which has been approved for the treatment of both stable PAD and post-intervention PAD, in a low dose manner in conjunction with a baby aspirin.

So we got a lot of good things out there. Also, we've got this incredible technology that the endovascular people have developed. Wonderful things. They're able to take technology to look inside the arteries, and to be able to clean them out and open them up for the inside without damaging the wall going past the median portion of the artery, which is really where the risk of increased trauma and also subsequent recurrence of the atherosclerotic plaques can develop. We've got new therapy where they're actually taking veins and stripping out the valves and turning them into arteries to provide backflow. This venous arterialization procedures that are amazing, that now we have a number of years of experience working with. So there's this incredible technology that's out there. So we can do a lot, that what we used to do, but first we have to identify the patients, then appropriately treat them, and then monitor them for the rest of their life. So those are where we are right now.