The Swollen Extremity in the Hemodialysis Patient - SD

Introduction

Hi, my name is Michelle Robin, and I'm professor of radiology at the University of Alabama at Birmingham.

Today I am gonna be talking about the swollen extremity in the hemodialysis patient.

Disclosure

First, a disclosure. I'm the director of an ultrasound core lab for an NIHU oh one hemodialysis fistula maturation study. I have really no significant conflicts of interest.

We're gonna talk today about what clinicians are looking for in the swollen extremity, how to triage with ultrasound, a brief slide on billing, 'cause it's very important. You need to bill exactly what you do. And, then we're gonna go over the focal findings that, you will see both common and uncommon. And, show examples.

Clinical Presentation of Extremity Swelling with Access

So, the extremity swelling with access is a very common indication. We see it coming out of the ER with less experienced personnel, that are not used to seeing a lot of fistulas and grafts. We see it in the outpatient department and also from the inpatient service.

Prior to Ultrasound Request

What should happen prior to the request for an ultrasound, and this is optimal, but doesn't always happen, first of all, that a clinician should do, a good clinical physical examination and get a good clinical history.

For example, do they have a graft? Do they have a fistula? When was it placed? They should also listen to the graft as well as, put their hands on the graft, because often if there is a stenosis present, you can feel the brewery, and then they may or may not have labs that are drawn to assess for dialysis adequacy, because this may be a problem that has brewing for some time.

Clinical History

So, for the clinical history, again, you need to know whether this is a graft or a fistula, and this is a plea to actually use the correct terminology.

A graft is an is PTFE material. In general, there are some newer fist or newer graft material, but generally it's PTFE and it's a connection between the artery and the vein by some synthetic material, either in the upper arm, forearm or in the thigh.

A fistula is a drug connection between the artery and vein. And, please, use the correct terminology. It confuses the sonographer and sonologist. If we see something that doesn't look like what should be there, we also need to get the history of a prior axis or a central line.

For example, if the patient has had a recent central line and now comes in with arm swelling, our focus is probably gonna be more on a DVT or a stenosis than, maybe access malfunction.

Recent surgery, again, it's important, to know if this graft is new or if the graft or fistula is new or old. And also recent hemolysis, and I'll show you an example later of a patient that came in with acute arm swelling after hemodialysis.

Each of these have different differentials.

Focal Findings: Pain

So first we're gonna start with a patient that comes in with a clinical history of pain. And, for the painful mass, generally we're thinking about infection. It could just be a hematoma, it doesn't have to be infected or, a pseudo aneurysm. Sometimes they can be, painful, sometimes they're not.

This is a very, this is a very gross example of a very large palpable mass. This is, 15 centimeters, obviously. It can cause pain just by its size.

The question is then is this infected? Well, I can't generally tell from these images, but we'll talk about that in a minute. But, what do we do when we wanna determine if it's a pseudo aneurysm, which is a very big consideration in this huge mass we put color on and, color will show that, this is a graft. You can see the graft material here. And, we didn't see any communication with the, hematoma around it.

Pain During Dialysis: Arterial Steal

The other thing that can cause pain, although in a slightly different, region, it's not a focal mass, but pain during dialysis. And sometimes people come in with that history and, and then sometimes that pain starts to get worse even off of dialysis. And in those exam, in those cases, we need to rule out steel.

So this is a patient that has, arterial steel, and the way that you diagnose that is this is the artery coddled to the fistula anastomosis. And here you can see, the flow going up towards the arm, which is the opposite direction that a normal self-respecting artery should be going in. And you notice that it's low resistance flow because it is feeding the artery.

What you do to put the icing on the cake is to transiently compress the graft or the fistula, and you'll see reversal of flow and a more normal high resistance waveform because then that blood flow is only going to the extremity. It's not going to the graft, it's or fistula itself.

So, don't compress it too long, but it's very, it's perfectly okay to do a transient compression to show this kind of image.

Palpable Mass

So now we're gonna move on to a patient that doesn't have a focal or that that does have a palpable mass. Again, an abnormal physical exam, not complaining of pain, but, a palpable mass. And again, the differential hematoma, and there may be gas, but remember that they stick these, grafts and fistulas with a 17, gauge needle in general. And so there could be gas from that.

So just because you see a gas bubble or two doesn't mean it has to be infected. But of course you can't exclude it.

This is a patient that has a very large palpable mass. And again, I I'm basically showing you, with reference to this and a few other images, the most obvious and, egregious, examples that I can show you to illustrate it. But be assured that most of the images I see in my day-to-day practice are much smaller than this, but this is a very large palpable mass, and you can see the graph going through it.

But what would would you do to maybe, figure out if this is an acute hematoma or if this is, because if it's an acute hematoma, the debris inside is, probably not gonna be very malleable. It will be like jelly. But if it's a focal abscess, there'll be a lot of debris and you may be able to compress it.

So given the right clinical history, we're worried about abscess. And this is a patient that if you use compression, you can see there's a lot of debris in here. So I'd be very concerned in the right clinical setting that this could be an abscess, but of course it could, I suppose, be a resolving hematoma.

You can also see this is, there's a graft adjacent with the, with the, tram tracks or the parallel lines. That is what we normally see, for a graft.

Pseudoaneurysm as Palpable Mass

Moving on to a pseudo aneurysm, as another etiology for a palpable mass, here is a typical pseudo aneurysm. This is a yin yang appearance, a two and fro. And then be sure when you're describing this to not call just this patent part a pseudo aneurysm. The pseudo aneurysm is really the entire mass, whether it's thrombo or not.

Now if there is no patent portion, then it's just a hematoma. I suppose it could be a thrombo pseudo aneurysm. But when you have something that is a pseudo aneurysm, be sure to not just describe the, the dimensions of that pseudo aneurysm as, within the patent portion, but describe and measure the entire mass.

This is another patient that, came in and originally was thought to have a big pseudo aneurysm. You can see there's a lot of blood flow here. It kind of has the appearance of a yin yang, and there is a lot of low or iso coic, around this graft. And there's a huge hematoma around this.

Well, when you look at it a little bit more carefully, there's actually a rent in the artery that, is, feeding this graft and here's the rent. And that's just draining into a huge peri graft hematoma. And, this is a surgical emergency. If you see this after you've diagnosed it, you should hold pressure because you can get a compartment syndrome in a hurry. And, the patient can bleed quite a bit into, an extremity.

Other Abnormal Physical Exam Findings

Other abnormal physical exam findings. Sometimes these patients have no thrill. Sometimes we get this from the dialysis, lab where they come in and the patient really didn't notice, but the, the, dialysis nurse says, I don't feel a thrill. But most of the time those dialysis nurses are quite experienced and they say, that means it's not working well and it's probably thromboses.

But the emergency room departments, generally tend not to have quite as much confidence as the dialysis nurses 'cause they don't see them every day. And, so they may send them to us, to make sure that there is, a thrombo graft or fistula and, it could be partial, it could be complete.

This is something that you can't just sign off the report. You need to call and, because someone may, want to do a declot of that graft or fistula sooner than later.

Now, if you feel or hear a brewery over a draining vein, that's more typical of a stenosis and, the most commonplace forest stenosis is in the draining vein. We'll talk about that in a minute.

Thrombosed Graft Example

First, I'm gonna show you an example of a thrombus graph. This is a graph that has a lot of low level echoes in it. We put color on it and, we don't see anything we could, optimize this image even further by decreasing the scale, going from a, medium to a low wall filter. And, even putting power doppler on if we really had any question about the fact that this graft is completely thrombo.

Draining Vein Stenosis Example

This is an example of a, draining vein stenosis and, the arrowheads show, again, the typical graft material. Here is the end of the graft, very nicely shown. You can see we can be very, very specific with regards to the location of the end of the graft in contradistinction to angiography where they may not know exactly where that graft ends.

And then where the asterisk is, is a stenosis. So here we're getting visual confirmation of a draining made stenosis, and we'll talk a little bit later about how to diagnose that and, how to assess the, severity of the stenosis.

Generalized Swelling

The physical exam can also be abnormal, not with a focal mass, but with generalized swelling. And when I think of generalized swelling, I generally think of central or proximal draining vein stenosis or occlusion. And occasionally we can see in these patients the DVT usually of the brachial or of the axillary veins. And those are things that we need to think about.

This is an example of a very swollen upper arm. And, this graft actually is occluded, we don't have color on, but it is, and you can see all this low or hypoechoic, fluid that is just edema that is in the interstices of the subcutaneous tissue.

So this is what is a typical pattern seen with generalized swelling. So we need to investigate that further to determine what the cause is.

DVT Example

This patient has a DVT. They have, a brachial vein thrombus. Remember the brachial veins are paired, so you may have thrombus in one of the brachial veins. It may be in both. And the way you can tell that they're deep veins, they're paired brachial veins that they travel with the brachial artery.

Poor Inflow

Another cause for an abnormal physical exam is poor inflow. Although, that is quite uncommon, as a reason to come to ultrasound, you can see a stenosis in the feeding artery or at the arterial anastomotic stenosis. Graft arterial stenosis is fairly uncommon, as is an arterial stenosis in the feeding artery.

A juxta anastomotic stenosis in the fistula is quite common, but it's an unusual cause of arm swelling because it restricts the flow in the arm. I define juxta anastomotic stenosis is anywhere within two centimeters of the fistula anastomosis.

So you can have, you can have edema distal to the graft. You could have difficulty in cannulation.

Other Clinical Findings of Stenosis

Another clinical finding of stenosis is prolonged bleeding at the needle sites or pulling clots out of the, graft or fistula. And finally, an unexplained decrease in ktov kt ov with a stable dialysis prescription. And, that is something that the clinician may have some idea that there is a stenosis.

Now if the clinician is pretty convinced that there's a stenosis, they really shouldn't be sending the patient to ultrasound. They should be sending the patient to angioplasty because, that stenosis can then be treated with angioplasty.

Triage with Ultrasound

So this is a diagram of really what we're looking for with that history, because you really don't know when the patient walks in the ultrasound suite. If we're gonna be looking for, we know we're gonna be looking for swelling, but we don't really know if it's gonna be focal or diffused. 'cause usually our clinical histories are, good, but, not, exactly, comprehensive.

If it is a focal swelling, really we only wanna look for that focal area looking for a mass. And then that mass can either be a hematoma, it could be affected or not, or it could be a, a pseudo aneurysm.

If there's more diffuse swelling distal to the axis, it's not exactly focal, but it's kind of not the entire arm, then you need to ultrasound the entire axis. And, when I'm describing this, this is what you should be using for, thinking about what you're gonna bill and what kind of ultrasound you need to do, because you don't always need to ultrasound the entire axis.

If you have diffuse swelling, then you do need to ultrasound the entire axis. And if you still haven't found a reason, then you need to rule out DVT in, ultrasound the, arm or leg. And the reason why I keep talking about access and extremity rather than arm or leg is because you can have a thigh graft. We don't typically have fistulas in the thigh, but you can have a thigh graft and, and, so then you would, be looking at the central circulation in those as well.

Billing

So one slide about billing in 2011, at least as of this date, if you're gonna only look at a focal mass, you need to do the soft tissue exam, 7, 6, 8, 8 2. And, if you're going to do the entire axis, either a graft or a fistula, that's, this CPT code 9 3 9 9 0, and that's graft slash fistula with doppler of arterial inflow, body of access, and venous outflow.

So this is a pretty comprehensive examination to my knowledge. There is not a limited, CPT code for just a limited study, but if you have a graft or fistula and you have a problem and you're evaluating it, then you need to do this, comprehensive study. You should not be looking for, looking to bill a, unilateral extremity arterial or venous code.

But if you then look for a, DVT in the upper extremity or in the lower extremity, you need to bill a limited or unilateral, CPT code, which is 9 3 9 7 1. But you'll need to check with your local people to make sure that these are correct, of course.

Focal Mass Referrals

So again, the focal mass is the majority of the referrals, and, usually there is a good focal mass clinical evaluation. So we kind of know what we're looking for when, so now we're gonna move towards talking about these individual entities that we see with a pseudo aneurysm.

Always turn color on because you never know when you're gonna get a pseudo aneurysm. Any hypo echo collection, you see turn color on.

One time I had a routine DVT study looked like a baker cyst in the popliteal fossa. And it turned out it wasn't a baker cyst. It turned out it was a pseudo aneurysm from a gunshot wound. Another time there was a, a big popliteal artery aneurysm.

So you need to always turn color on the hypo coic, collections, particularly when, you're, looking around a graft or a fistula, which have so much blood in them.

Now the graft wall will commonly degrade to form little pseudo aneurysms, and in general, nothing is done about them until they get to a, a reasonable size. And that that definition of reasonable changes with the, with the patient and with the surgeon.

You may also get a pseudo aneurysm from inadequate pressure after removal of the dialysis needle.

So this is an example, a gray scale image of a, degenerating graft. And here's all these little pseudo aneurysms is pretty common with an older graft. And this is color putting color on. And you can see all these little patent out poachings from that graft. It is a synthetic material, so it cannot repair itself after repeated sticks.

Pseudoaneurysm Evaluation

So again, in, focal mass evaluation, now we're gonna start talking about the individual entities in more detail that can cause a focal mass for a pseudo aneurysm. Remember to optimize your settings for low flow. Of course, you, if it's a big rip roaring pseudo aneurysm, then you can turn up your settings as needed.

But first of all, optimize your gray scale and maybe bump up the gray scale gain just a little bit to make sure that there's not some low level echos or some hypo thrombus that you're missing.

Then turn the color gain up until the pixels are displayed just outside the vein where they shouldn't be, and then turned down until they're just, gone. Decrease the color scale. Decrease the PRF and make sure that you have a low wall filter. And just to be sure that the probable hematoma that you're looking at isn't a pseudo aneurysm, with low flow. And if you really think that you need it, you could put power doppler on. But typically, it's such a superficial structure that we don't need it.

Then you need to assess the depth of the pseudo aneurysm, and that's very important.

The other thing that we don't typically do in ultrasound is to turn the light on and you need to look at the patient's skin assess. First of all, you could look with gray scale, put some color gel on or some gel on so that you can see where that, anterior most wall, the pseudo aneurysm is and where the skin surface is.

But then look with the lights on and make sure that that skin surface isn't ulcerated because these can bleed, the patients can exsanguinate. And that does occur every year in the us I can't tell you how many people actually do bleed out, but I know it occurs sometimes I've been so worried that I've gone over with the patient, what they should do if this, if they start bleeding and you'll gonna wanna tell 'em to, you know, grab their arm, put a tourniquet on if they can, or a belt or something like that. Not just hold gentle pressure, but very, very hard pressure. And, call 9 1 1.

Now, you may call the surgeon. They say, oh, that's okay, I can come to clinic in a couple days. If you're that worried about the patient that that could, that that pseudo aneurysm could, rupture, then you need to say, I'm sorry, no, this patient has to go to the er or they have to come to your surgery degree clinic today. It's very, very acceptable for you to be that firm. And the patient will thank you for it.

And again, you may need to discuss the rupture scenario with the patient. I haven't done that very often, but those times that I've been very concerned I have. And, occasionally we do escort the patient to the emergency room.

This is an example of a graft, pseudo aneurysm. It is, off the distal end of the graft and it's a big one. And, we generally this is big enough to deal with that day or put 'em in the hospital at least. So they're under observation.

This is another odd pseudo aneurysm. It's a patient that, we were mapping them for a dialysis, access and they had a brachial pseudo aneurysm. And you can tell that it's old because there's some calcification around the periphery here. This pseudo aneurysm is likely from a prior, needle stick or maybe a line. And you can see this is a typical pseudo aneurysm.

Again, remember when you're describing the pseudo aneurysm, talk about the entire, surface measure, the entire volume of the pseudo aneurysm, not just the patent portion that's gonna be important at surgery.

So would you like to do thrombin injection on these? I don't think so. I think it's, generally there is a, wide neck for these pseudo aneurysms. You run a big risk of having, the thrombin that you're injecting go back into the circulation. And these are best handled surgically in the old days.

When we used to do compression, I have tried compressing a few of these when they were relatively acute, but most of these have been around for quite a while and you will generally not be successful with compression. So I would just, send them to the surgeon. Now some of these small ones, they don't have to go to surgery right away, they'll just watch them.

Infection vs. Hematoma

Now if you don't have a pseudo aneurysm and you have lots of echoes, like that other case that I showed you, you need to worry more about infection. But you really can never know for sure whether something is infected or not, unless there's gross air bubbles within. But again, a hematoma is very common. These patients are on hemodialysis three times a week for four hours at a time. So they've got lots of hematomas.

And when you're describing this, be precise as to the location. Say where exactly it is, because if they go to surgery in a day or two, that that, hematoma may have decreased in size. So you need to be precise.

Diffuse Swelling Evaluation

Alright, so now if we have swelling moving onto that, usually the swelling is distal in the extremity. And, then you need to look at the entire axis. And when you ultrasound the axis, either a fistula or a graft, you need to look at the feeding artery at least the lower third, the anastomosis of the artery with a graft or fistula. And if it is a graft, you need to look at the arterial and graft anastomosis and then the graft and venous anastomosis, or if it's a fistulas, the arterial venous anastomosis. And then you need to look through the entire draining vein.

Hematoma Causing Stenosis

This is an example of a hematoma causing a stenosis. There's so much of a hematoma here. This is up near the axilla that, it's frankly causing compression. And these may get better, but you may have to have evacuation of that hematoma. And you can tell this is a pretty decent, stenosis, not only visually, but because the systolic velocity is over four, and I don't usually use that as a a gradation, we use it as a peak systolic velocity ratio, but I know that the, feeding artery was a lot lower than four.

Evaluating Stenosis Severity

So how do we evaluate stenosis and how, what the degree of stenosis is? We look at the peak systolic velocity ratio, and this is a tube. This is all just plumbing. Here's the stenosis. At b the blood flow is coming in from a, here's the post stenotic dilatation, and here we obtain a pizza dog velocity at b, take a, cysto velocity at a two centimeters upstream from the anastomosis. And, we use that ratio to determine the, degree of stenosis along with a visual assessment.

So this is an example of a juxta anastomotic stenosis in a fistula two centimeters proximal to the anastomosis. The feeding artery PTO velocity is 102 centimeters per second. At the stenosis, we have a PTO velocity of 861 centimeters per second. So that gives us a peak sto velocity of ratio of eight to one.

What ratios do we use? Well, it varies a little bit for a fistula. If it's a just to anem stenosis, we use a POG velocity ratio of greater than three to one and a visible narrowing for a graft at the arterial graft anastomosis, that blood has to turn on a dime and go whipping back up the arm. So, sometimes you can get a pizza, so velocity ratio of even greater than three to one, and there'd be no apparent stenosis at all. So we require visible narrowing as well at the venous graft anastomosis or traft, that's the most common.

The venous graft is the most common area of stenosis, and we require a pxi salt glossy ratio of only two to one or around two to one, but also we need a visible narrowing.

The only place in the graft that, this doesn't apply that I've been fooled at and I'm is, near the apex of the graft, in a forearm loop graft or perhaps in an upper arm loop graft. Sometimes the, most coddled portion of that graft as it loops around can do a little kinking. It's questionable that angiers don't call that a stenosis, but it, it is in effect a functional stenosis. But you have to, make sure that you don't inadvertently send a patient for a stenosis that is just a kinked, a kinking of the graft that the angiers aren't gonna be able to angioplasty.

And then in the feeding, in the feeding artery or in the draining vein, we use a pizza stock velocity ratio of greater than two to one and again, visible narrowing.

So it should be, we should measure blood flow, which is also called volume flow so that we get some degree, some assessment of the degree of blood flow, whether it's five ccs a minute or 500 ccs a minute or a liter a minute, it's gonna, lead us to a little bit different conclusion and we'll talk about that in a minute.

DVT in Severe Swelling

If there is severe swelling and we haven't found a definite stenosis yet, you need to look for a DVT look in the brachial veins and in the axillary veins. And then if it's a lower extremity thigh graft, you need to look at the common femoral vein and external iliac veins. If you can, then you need to look centrally and, those central veins are the internal jugular vein and the subclavian vein or the common femoral veins bilaterally. And, you need to compress those to make sure that there's no stenosis, or clot there. And then put color and spectral doppler on.

And what you're looking for is, a spectral waveform that's abnormal and monophasic. We're assessing respiratory ity and also assessing transmitted cardiac pulsatility And, in the, in the, detection of central stenosis, we also can look at the brachiocephalic vein in the SVC. We can't always see the SVC, we can't always see the brachiocephalic vein because they are covered by lung.

But, and, likewise, the common iliac vein and IVC are covered by bowel, but sometimes you can put a small sector transducer either in the sup sternal notch or above the medial clavicle, or in a thin patient. You can look at the common iliac vein in the IVC. And sometimes you can actually see, well these central structures.

So you need to basically try, This is a patient that has had a recent angioplasty, had a fistula, here's that fistula coming in. And, all we're seeing is a dilated vein filled with clot. And, their angioplasty was obviously unsuccessful and their, subclavian vein is occluded.

This is putting color on, and you can see that there's a pulsating artery adjacent to where, the subclavian vein should be. And we of course verify that with the still image with doppler on the little bit of pulsation you see is from arterial, pulsation.

Now this is another, this is the same patient actually. And, so left subclavian is thrombosis, right? Internal jugular vein is monophasic. I call this very tightly. It needs to go all the way back to baseline to normal. And, the subclavian vein is also monophasic and that would infer that there's a central, stenosis or occlusion. And since this is a bilateral process that thrombus from the left may extend all the way to the SVC.

This is another patient with very monophasic, central venous flow on the right and also in the left, very, very abnormal. And this is a patient with bilateral brachiocephalic vein occlusion. You can see where, this person's, left, medial subc vena and, brachiocephalic vein is, and you can't even see where the right side is as well. Here's the SVC.

So, this patient's got a significant, problem and cannot have a, fistula ora graft in the upper extremity.

This is an unusual finding. We see it about once a year now. And, this is a, a patient that has reverse flow in the internal jugular vein. It's pretty cool when we see it. Notice that there is good respiratory ity, which means that there's some collaterals that are, connecting to the central chest and this is the angiogram of that patient.

And here is the occlusion of the brachiocephalic vein and there is, what flow is present in that internal jugular vein. Is, coming up in, in a retrograde fashion.

Further Evaluation for Abnormal Waveforms

If you see abnormal waveforms, what you need to do is to get a fistulagram or an MRI for central vein evaluation. For the, for fistulagram that could potentially be therapeutic in selected patients, because they could perform an angioplasty or they could place a stent. So if there's a strong suspicion you could do that, if there's a less strong suspicion, you could do an MRI.

But that is an issue these days with patients with elevated creatinine. We don't usually give gadolinium because of the possibility of nephrogenic systemic fibrosis. However, there is an alternative. You can't perform MRI without contrast using cardiac gating to assess the central veins. You're gonna need a newer, package probably on your MRI, but, often, people have that capability.

Negative Ultrasound and High Access Flow

Now what happens if the ultrasound axis is negative and there's no DVT? What do you do next? Well, this is usually in the setting of high access flow. So you'll end up with a patient that maybe has a liter or more, going through their fistula or graft. You'll need to do an angiogram because you'll often in those cases find central stenosis or occlusion.

So in those patients with diffuse significant arm swelling, if it's only mild or it's not causing any issues for that patient, you probably shouldn't refer them for an angioplasty. You should wait until the swelling is severe because you may extend that access life. Because there are some papers that that demonstrate that if you angioplasty and asymptomatic stenosis, that you may be causing, more harm than good and you may shorten the access life.

But, successful angioplasty plus or minus stinting will usually resolve the symptoms of edema.

Summary

So in summary, we have talked extensively about what to do in the swollen extremity. With an access, you can triage with the clinical history and examination, you can pretty much figure out what you're gonna have to do. Basically, you determine whether there's a focal mass or diffuse swelling.

If it's a focal mass, you can do a limited examination and just bill a subcutaneous tissue code. Now I do put the Doppler on just to assess patency, but I don't charge for that because it, it's a, it's a one second on and off. So, remember those can be a, a much more, shortened exam.

But if it's diffuse, you will need to do an entire access evaluation. And then if you don't see an etiology for, the swelling in terms of access malfunction, then you need to go on and do a DVT study. And, if you still don't see any etiology for that swelling, you need to study the central veins.

Thank you.