Good afternoon, good evening, everyone. Thank you for attending today's webinar. Earlier this month, we heard about assessing patients post-operative or post-procedure with non-imaging techniques for dialysis patients, and tonight we're going to hear a presentation on assessment using imaging pre- and post-procedure. The title of tonight's talk is The Dialysis Patient, Hemodialysis Imaging from Preoperative Assessment to Postoperative Imaging. My name is Laurie Lazansky, and I'm the chair for the SVU eLearning Educational Committee. And before we begin, I have a couple announcements to share with you from the SVU office. First, this webinar is going to be recorded, and it's going to be available online for attending through the SVU website at no charge. Please take a moment to familiarize yourself with the GoToWebinar program we're using. Everyone should see a question section along the side menu of your screen, kind of near the bottom of the choices, just above the chat. So just please type in any questions that come to mind during the presentation, and then at the end of tonight's talk, we should have some time for discussion. Now, in order to receive your CME from tonight's lecture, you need to wait for an email from the SVU office containing an evaluation. You'll get that email in about 7 to 10 business days. When you get it, you complete the evaluation, then your CME certificate will automatically pop up. So that's it for announcements, and so let's get started. Tonight our speaker will be Matthew Allen. Matt Allen, he began his career as a vascular technologist in 2005 at the University of Florida Health, where he worked for the Department of Vascular Surgery for 10 years. In 2015, he went on to manage UF Health's non-invasive cardiovascular department for the next five years, and then in January of 2020, he transitioned full-time to academia, where he taught the vascular curriculum at Santa Fe College in East East Florida. Matt is currently the department chair for allied health programs at Santa Fe College, and he serves on the board of trustees for CCI, that's Cardiovascular Credentialing International, as well as serving on the board of CAHPS Advanced Cardiovascular Sonographer Co-op. He is a contributing author of the Vascular Reference Guide and its workbook, and human analysis studies in this patient population has always been near and dear to Matt's heart, which I'm sure you'll appreciate after hearing this presentation. So with that, please welcome Matt Allen. Thank you, Lori, and thank you, Missy. Thank you to SBU, and most importantly, thank you to everyone that carved a little bit of time out this evening to be with us. I hope to have some really good Q&A. We're going to go through a lot of information, kind of exactly what Lori said, from the preoperative planning all the way through the postoperative imaging. So I have no disclosures, and this is also the objectives that you probably saw when you signed up for the webinar. We're going to talk a little bit about the capabilities of the imaging, kind of define what those preoperative imaging tests are that help drive. of the planning and the surgery for that type of dialysis, access that the patient will receive. And then through post-operatively to some imaging protocols, criteria, and then further talk about AVFs versus AVGs, a little bit about staged procedures depending on the vein that they use. And then, of course, what would a discussion be about hemodialysis if we didn't talk about some post-operative complications? Again, no disclosures. So I thought we'd kind of start off by just quickly kind of framing the types of dialysis. So, you know, we're gonna have patients with a catheter, a port, that's a course for short-term dialysis, hopefully. And then we're gonna concentrate mostly, like I said, on arteriovenous fistulas and arteriovenous grafts, which is what we, as vascular techs, are going to see the most of, likely, in the vascular lab. And, of course, there's peritoneal, also for long-term, that's completed at home. What's near and dear to my heart, or what made this patient population so near and dear to my heart is these are folks that we're gonna see in the vascular lab often. Unfortunately, just due to the frequency, the volume of cannulations that they get with their site, those complications incur. And then, you know, we're gonna see them to try to help figure out what's going on and then kind of work alongside with the physician. But you really are able to kind of develop this really, I'd say, cool relationship with these patients that you get to see. Their time is very valuable. And these are their lifelines, which makes it just that much more important. They're not always going to be on time. Sometimes they're gonna be late and they're gonna no-show. But I always had to keep that in mind, that this is their lifeline. Most of their time is spent in the hospital or in dialysis. So if you can look through the lens of truly that patient care aspect, it takes some of that stress stressors off of maybe not just that patient that's on time in and out in a Jiffy. So a special population that's near and dear to my heart. So what studies should be done when working up a patient for placement of a dialysis access site? It involves, you know, so many different things, arterial, venous, both deep and superficial, you know, central veins. So what do we do as vascular techs to help paint the best picture for the surgeons that are going to be creating these access sites for these patients? So I wanna kind of start by saying that location, the most ideal location when placing these in a perfect world would be, you know, upper extremity. And then the furthest distal point of the extremity, so at the wrist. That's the most desirable starting point and also in the non-dominant arm. So the surgeon can typically work their way up an arm if you start at the wrist and say the patient's site fells, typically you can work your way up and maybe create a new access site in the upper arm, but rarely can the physician go from the upper arm back to the lower. So you wanna start as far distal and then that kind of creates a little more, a few more options throughout that patient's dialysis journey, if you will, should they have complications or have to abandon that particular site. So using me, for example, I'm left-handed. So I would want to receive a fistula on my right arm. And of course the distal most point, I'd want a radiocephalic. So we're gonna kind of talk about what sets the patient up best for that kind of configuration. And then, you know, what to look out for as far as some post imaging complications that may occur. So that testing that I was referring to. So this set or group of preoperative tests that determine if a patient's a good candidate to receive a fistula, whether it be an AVF or an AVG, which we're gonna talk more about in a couple of slides, but we want to evaluate the deep system. Those are gonna be our draining veins. We also want to assess the superficial veins. So in the upper extremity, those would be your cephalic vein, the cilic vein. And of course we wanna include that median cubital vein around that elbow and a cubital fossa area that connect the two. And then we also wanna do arterial assessment, which feeds that access site. There's two additional things that we wanna include. One's called an Allen's test. And we're gonna talk a little bit more in the next slide. That's to determine the dependency of the radial and ulnar, if there are any. And then of course we wanna measure some arterial diameters to get a good indication of the size. So what's the value of each of these and what are the ideal results? Like I said, the DVT study, you wanna check the patency because those veins are where the outflow will go from the actual access site. So for example, if we had a fistula placed in the upper extremity, we would want to have preoperatively assessed the subclavian adenomate veins as central as you can to help detect if there are any potential obstructions that would postoperatively or post access placement cause any complications. So in the preoperative assessment, you wanna make sure that you're looking at the venous waveforms to make sure they're consistent from right side to left side, nothing that would indicate some outflow obstruction. Vein mapping, we wanna make sure that the superficial veins that could potentially be the actual body of the access site are able to accommodate that arterial flow once they're hooked up to an artery. So preoperatively, ideally we would like that superficial vein to be three millimeters or over and we can deem that what's called adequate. Marginal where it's close but not quite there to where we might want to put a tourniquet on or bring them back in close to preop to remap them. That's kind of in that 2.5 to 2.9 millimeter range. And then inadequate, something where it just might not be a good candidate of a vessel to create an access site would be something less than 2.5 millimeters. So in addition to the diameter of the vein, you also want to assess the integrity of the vein wall. And the reason we wanna do that is because if it's sclerotic or thickened, something that might impact the compliance of that vessel, rather when the surgeon hooks it up and connects it to an artery, if it's not going to mature and accommodate that arterial flow, it's not going to mature enough to likely become a candidate to actually, for the patient to have dialysis through. We also wanna look at prominent valves. Even though those are assessed intraoperatively, potentially to be lysed, we always wanna draw attention to that because if that valve is left there when they attach that vein to a high pressure artery, we're gonna see a pretty instantaneous stenosis. So anything that we can draw attention to preoperatively to help paint that picture for the surgeon is good. Arterial study, of course, that's our inflow. So we're looking for maybe a physiologic test, a WBI that has an index around one. Good multiphasic waveforms, but we wanna make sure that we keep an eye out for any falsely elevated indices that might suggest that medial wall calcification's present for that diabetic population. Again, that compliancy could cause or lack thereof problems down the road. And then the Allen's test. So that's, again, to test the dependency of the radial and ulnar artery. And we have, it could be either a complete palmar arch, which means it's not dependent on either artery, or an example that I gave here, it could be radial dependent, meaning that that surgeon would want to know that piece of information so they don't go in and create a radial cephalic fistula that would then cause that hand and fingers or fingers to be ischemic because that hand is dependent upon that radial artery per flow. So those are the importance and kind of grouping, if you will, of preoperative tests that really paint a picture of what is the best option for that type of configuration, whether it be fistula or graft, or say that the patient doesn't have adequate vein. It helps really to kind of paint a picture and plan of care for that patient that still needs to have some kind of method to dialyze. So before we go on and talk about imaging and different types of dialysis, which I've kind of already started to use, I just wanted to make sure that everyone was familiar with them. So access site refers to that area on the patient's body where the catheter, the dialysis tech, can cannulate or insert that dialysis catheter into the patient. They'll pull that blood out, it'll be filtered, and that clean blood will go back in. So that's all done at that access site. Cannulation is just that. It's the ability to insert those catheters into the patient's site. The inflow, when I refer to that, we're talking about the artery that feeds that fistula or graft, which is typically in the upper extremities, brachial artery, radial artery. In the lower extremities, it could be the common femoral artery or femoral artery. And the outflow vein is just that. It's the vein that actually drains the access site. And anastomotic sites, and we're gonna talk about which types of dialysis methods have one versus two sites, anastomotic sites, but that's just the surgical connection between the artery and then the vein, or synthetic material if it's an AVG. So let's kind of start to talk about the differences between AVFs, or arteriovenous fistula, versus AVGs, arteriovenous grafts. And really it has to do with what the patient has to work with in terms of conduit. Both have the same goal of creating that site for us to be able to dialyze through that dialysis tech to be able to cannulate during dialysis. We still want the same kind of things or characteristics from it. It's going to, you're going to have a thrill. You're gonna want it more superficial to the surface of the skin so it's easily accessible for the dialysis tech. Because you want to pull large volumes from it. So the goal are, it's the both through the lens of a vascular tech, these are the two that we're going to see most often in the vascular lab. So to kind of break out the AVF or the fistula a little bit more, you know, here's an illustration to the right where it has one anastomotic site. That surgeon attaches that native vein to the native artery and it has one anastomotic site typically referred to as that arterial anastomosis. And when the surgeon connects that and creates that anastomotic site, then that outflow vein or what will become that access site typically takes, you know, two to three months to what we call mature. And over time that arterial pressure that has occurred since we've attached that vein to the artery, that vein should grow and mature to the point where it's able to accommodate a high volume of flow. And we're gonna talk about the hemodynamics and what to expect as far as imaging, which is going to be a very low resistant waveform. So now we've created a, with just one anastomotic site, this fistula, we've created a high pressure and high flow that over the next three months will kind of bake, if you will, or get ready to mature. And it will be able to be used if everything goes well in just a few months. So depending on, and again, through the lens of an upper extremity, your superficial vein options are cephalic or bacillic. So we know the anatomic location for cephalic vein to be more superficial, more lateral. So if you translate that into an AVF, it's going to be more accessible for that dialysis tech. But perhaps that cephalic vein wasn't adequate for this particular patient. So the option is a bacillic vein. Well, we know the bacillic vein to be deeper, but then also more medial. So that makes it less accessible for the dialysis tech to be able to cannulate dialysis. And again, we know these to be sometimes four hour sessions. So something to help this alleviate some of those barriers is staging. So if we have a great bacillic AVF, typically the surgeon may create in stage one, the connection or that anastomotic site from that bacillic vein connecting to the, say, brachial, wait that two to three months for that maturation to occur. This is when they may come back to the vascular lab or receive imaging to say, okay, has it matured? Or is there a good flow that will allow us to then go on to stage two, which is then going back to the OR. And then the surgeon doing what's called a transposition or superficialization to that bacillic vein to almost swing it over, if you will, to become a little more lateral, but then also more shallow. I mean, again, and it's all in efforts to be more accessible for that dialysis tech. So they're easier to be able to cannulate and then complete that dialysis session. So if the patient doesn't have any of their own vein that can be used, but they still have as conduit, but they still have good arterial flow and then good draining veins, their deep system is patent. Something called an AVG or an arteriovenous graft may be a good option for them. It's where it could be a most, typically it's a dialysis session. I'm sorry, a synthetic material such as Dacron or PTFE, that polytetrafluoroethylene. And they attach one side to the artery, that would be the arterial anastomosis or proximal anastomosis. And then the other end, they would attach to the vein, the draining vein. So that would be the venous anastomosis or sometimes referred to as the distal anastomosis. These are ready to be used quicker, sometimes within a week of placement. But the downfall of these are, that's a foreign material in your body. So infection is an off the table. So while it might be the patient's only option, a common, let's say it's not uncommon for a patient to have that complication where that fluid builds up and infection ensues. So if we can use the patient's vein, that's always best. But if you look over to the illustration to the right, you'll see those two anastomotic sites, one with the artery that's supplying the flow to the access site, and then the other attachment with the vein. And that this is a particular configuration is a particularly a loop. Sometimes you can have a straight graft where it just, it's not a loop, but rather straight. But that upside down or this U rather right here, let me see if I can get mine. So here's the arterial anastomosis, venous anastomosis. And this area right in here is where the dialysis tech would cannulate and then dialyze through. So just some examples of configurations, which is, you know, configuration is just, well, what type, what artery did they hook to what vein? We term that as configuration. So common configurations in the upper extremity include radial cephalic, which would be down at the wrist. Sometimes it's referred to as semino. And again, all of these will have one anastomotic site. Another common configuration in the upper extremity is that brachial basilic, which is what we just talked about as far as the two stages that may occur to kind of superficialize or transpose that vein to where it's more accessible. Brachial cephalic, which is typically the anastomotic site for those brachial basilic and brachial cephalic would be around the antecubital fossa. So those, these basilics and cephalics are going to be upper, typically upper arm. And then lower extremity configurations, those are oftentimes they have the two anastomotic sites. So for example, common femoral artery connects to the common femoral vein, common femoral artery to common femoral vein. That would definitely be a loop because we know in that groin, that section's not long enough for it to be what we call a straight graft or straight AVG because you need room most of the time for it to be a loop so that the dialysis tech can actually access it and complete that dialysis session. So we have done the preoperative imaging. They've had their surgery. They've created an access site. What happens next? We want to kind of know why the patient might come back to see us. And in green, I just kind of shaded these a color because they may not come back for any complications. Sometimes the surgeon likes to send them back just to see before they dialyze, is everything looking good? We don't have any suspicions that anything is wrong, but before we send them to their first session, they may come back to the vascular lab and have it imaged prior to cannulation. So assessing the flow, the velocities, and then the volume flow, which we're going to talk more about will really help determine is it mature? Is it ready to go? Is it ready to be cannulated? Sometimes it's not always that good of a situation for the patient. They may be coming because in a clinic visit or at dialysis, they may have issues, but in a clinic visit, they may have a loss of thrill. They can't feel it anymore. Pulsatile, pulsatilityity. And we know that there should be a thrill, but this pulsatility is beyond that expected thrill. So maybe something associated with a stenosis or something of that sorts causes a brewy aneurysmal segments. And sometimes we can actually see these to the naked eye. Sometimes you can't always do that, but sometimes we have patients that come in that look like they have a rope appearance underneath the skin. And we can already tell that that site, that dialysis configuration is indeed aneurysmal. If the patient's arm is warm, red, ulcerated skin, that's something that we wanna pay close attention to because that can be either a sign of infection or that ulceration that if that skin becomes very thin, it could ultimately become a risk for that to rupture. And under that higher arterial pressure, that's very concerning. Because oftentimes when dialysis techs find a cannulation spot that has been successful, it kind of almost becomes a go-to area, and that can over time break down the skin and cause some maybe longer-term complications for the patient. They could present with swelling in the extremity that the access site is in, and, you know, we look for fluid collection, we look for obstruction in the draining vein to make sure that there's not, you know, DVT that's preventing that outflow. And then, of course, those issues of dialysis, low volumes during the actual session, so say it's not pulling as much blood as they'd like to, or just difficulty cannulating the actual site itself, and sometimes that can be because there's clot there or stenosis, and then sometimes it could just be because it's deep, and sometimes if that's the case, they may come back to the lab for a fistula or AVG duplex. We find everything as patent, nice and open, but it's just really deep, and in that case, we may mark it. The physician may write orders for us to mark it so then they can easily kind of guide themselves and decannulate that fistula or graft. So this is something I put this year because this is sometimes the way I felt when I just started doing this as a younger tech. So how do I prepare for this? I had no idea kind of what I was in for, or a patient that may have had multiple AVFs or AVGs that have failed. I'm not quite sure, you know, where I'm starting, and that's okay because you're going to do some exam preparation. Just for anything, you want to look at prior imaging reports, prior OR reports to try to determine, do you know what configuration it is? Do you know what the graft material is? Because as we know, that synthetic material for an AVG creates a higher susceptibility for patients to accumulate infection or fluid. Have they had prior interventions? Was there stenosis last time? Did they fix it? Can we expect it again? Ask your patient questions. Discuss their symptoms. You know, if it's a patient that just had their first fistula placed, have they done dialysis yet? If they haven't started dialysis, maybe it's just in preparation for, you know, the chances of that patient having a pseudoaneurysm or, you know, a dissection or an aneurysm might be lower than somebody that's currently being suscepted to constant cannulation of that access site. So you want to look at your patient, determine what transducer that you're going to start off with. Typically it's a linear. Sometimes if it's swollen, the patient's extremity is swollen, or if you're really trying to look centrally at those draining veins, we may want to switch to that curved transducer. Bandages and dressings are, they can be a bit tricky and you always want to follow your institution's policy. However, you want to take down as much dressing as you can while still keeping pressure. Say they had come from dialysis the day before, sometimes even the day of, and if there were complications, you may not be able to take all of that down because that pressure dressing is there for a reason. But you want to come from every which angle you can, posterior, anterior, get that curved transducer out. Because the worst thing you can just do is say, unable to visualize dressings and bandages were in place. We can take some of it down, maybe just the external wrapping. We can try to get as much as we can and give the physician as much information as we can to try to help that patient and determine the care plan. This is something that is worth taking a few minutes to do and just set the patient up comfortably. If you have the luxury to have warm blankets or a pillow or adjust the bed, some of these patients have cardiac issues to where they may need the back of the bed raised. It's worth beyond just the level of patient care that we should supply. It's also worth setting them up and getting them comfortable so then they're not moving around as much during the exam. Because as we're going to talk about shortly, you can actually cause some pressure of your own with your hand and cause a pseudo stenosis. If they're moving around, you're having a hard time getting your images, it's just going to prolong that. Instead, if we can get that settled up front and get them comfortable, I try to do that. Let's dive into the protocol. Of course, this may vary from site to site, but I think the key is to follow, if your lab is accredited, that protocol and then be consistent. So we always started the exam off with a short access suite, starting from that inflow through that anastomotic site or sites, depending on if it was an AVF or AVG. That helps to determine the course, what to kind of expect, kind of create some foreshadowing. Do I have several pseudos? Do I have an aneurysm? Does it appear to clot off halfway through? And then throughout the exam, you want to be looking for a magnitude of things, fluid collection, hematoma, venous branches that may be impacting the flow. We're going to dive a little bit deeper in some of these and the complications in the last part of this discussion, but calcified valve sites. And then at the end of the exam, you want to go back to short access, do some measurements in short of those pseudoaneurysms, if you're able to visualize them. And then throughout that exam, you're, of course, along the way, going to be getting long access color, grayscale color, spectral Doppler measurements, and the inflow, arterial anastomosis, the origin, the proximal. Some centers have you take two in these areas. So mid and a mid two. Typically, you'll do your volume flow, perhaps in the mid segment. You just want to make sure that it's a non-tapering kind of straight segment and get those flow volumes, which we're going to talk about coming up soon, what those are and the importance of that. Then, of course, distal. And then if it's an AVF, you would just continue on into that, the ipsilateral draining veins. So that same side, that axillary and subclavian vein, as central as you can get. If it was an AVG, you would have included in between the distal anastomosis, you would then do the venous anastomosis and then on into your outflow and then draining veins. So with any kind of abnormality, you don't want to just snap one picture. You want to try to get a loop. You want to try to at least prove this pathology in at least two images. Some physicians are very particular. They may only want two pictures. They may want more. So of course, this is going to vary from facility to facility, but it's always best practice to make sure that you have multiple images, kind of take a defensive approach to where if somebody that didn't even know what was going on was reviewing your images, you could easily prove that, yep, there's a pseudo, there's a second pseudo, here's a stenosis, that's a fluid collection. If we take that kind of defensive approach, I think it really helps to paint a good picture and again, translates to a good care plan for the patient. So our methods of evaluation for these imaging studies, we rely heavily on spectral Doppler velocities. We incorporate ratios from those velocities. We look at diameter measurements because if we have a true stenosis, we should always also see a corresponding diameter reduction. We want to look at the depth. If we notice that this access site is so superficial, it's almost right underneath the skin, that's very important, just as if it was 10 millimeters down and it could cause complications at actual dialysis. Also, just really important information to kind of mine and present to the physician. We want to collect volume flow measurements as just additional information about how much flow is going on in this access site. So over here to the right, you'll see that I have two different images. Some centers have their flow below the baseline and that traditional venous flow below the baseline. The facility that I practiced at, we always, since it was arterialized, we kept our flow above the baseline. But just don't be caught off guard if you perhaps see that flow underneath the baseline as well. And again, careful attention should be taken to not create that quote-unquote pseudo stenosis. And what I mean by that is if your hand, if you're like me, you're concentrating, you may put a little, your hand may be a little heavy and then you realize, oh, that elevation of velocity, I can't produce it, reproduce it, and it's actually my own pressure. So you want to make sure that you're not applying too much pressure on the transducer, creating that quote-unquote pseudo stenosis just at the actual location that your hand is at. So here are some published criteria that you may see. Again, ratios are really important. Less than two, we know to typically be normal. Greater than two and that inflow and body of the access, if it's greater than two, it typically correlates with a greater than 50% stenosis. It's a little bit different, a little higher threshold at the anastomotic site because of that sharp bend that it takes. So it's accounted for by raising that threshold from two to three, so kind of distinguishes between normal and abnormal. And then when you get down to volume flows for an AVF, because oftentimes that conduit, the diameter may be just a little smaller than what a synthetic material might yield, greater than 500 millimeters per minute is normal. And then for AVGs, we want to see something greater than 800 millimeters per minute. So again, if you see an elevation, you really want to try to capture a corresponding diameter reduction. So let's talk about normal before we dive into the abnormal. We already talked, it's going to be a high flow, low resistant waveform. And over here, and over here we have just that. Almost, I'd say 275, 270 centimeters per second, nice low resistant. We want to make sure that diameter is nice and wide, depth, high flow. Oftentimes because of these high flows, you're going to have to increase that scale setting 50, 60, and even higher if there are situations of stenosis. And here we just have the skin surface down to the most anterior portion of this access site to get our diameter. And that looks to be within 4.3 millimeters of the skin surface. And here, well be it, my color game was just slightly over. You wouldn't even want to turn that down just a hair. You can see the scale's really high, but you can see a nice low resistant, high flow waveform in your mid AVF. So we've talked about volume flow. So again, the purpose of volume flow is kind of an additional set of data to determine how much flow is going through the site. Oftentimes this is taken into account if somebody has a stenosis, but it's not really critical. How much flow do they have? The surgeon may say, well, they've got really good flow. We're not going to do anything. We're not going to intervene right now, but they're going to come back in a couple of months, maybe not even that long and see if their flow has changed or that stenosis has gotten worse. So it helps, it's kind of incorporated into that decision-making process. So we're going to go over an actual image in the next slide, but we try to get a non-tapering straight segment. Typically in the mid, some facilities do an inflow. It incorporates the time average mean velocity for the waveform, incorporates the diameter, and it has some markers that we're going to place on the waveforms. And we try to measure one to three complete cycles. You just want to be consistent. Your lab may have a very set specific protocol that they have. So obviously follow that. And where I came from, we did three complete measurements. So then we had an average. So that way we knew that we weren't having just an erroneously high number or a really low number. We had three consistent volume flows, pretty much in that same consistent area. So here you can see the sample gate is open. The width of the vessel, the calipers are kind of pushed against the vessel wall. Here is that mean velocity, that time average mean velocity. You place your marker at the beginning of the onset of systole. And then we chose three waveforms to be consistent. So first marker, onset of systole, that second marker, the end of diastole. So you're capturing three waveforms. So without all of these labels, you can see just that over here, a little less kind of jumbled. But you've got your calipers pushed out, your sample gate open, your markers incorporating those three waveforms. And you can see that has a flow volume of 722 cc's per minute, which we can see that that's an ADF. It's above 500. So we've got good volume flow. So that's normal. We've talked about normal. We've talked about volume flow. Let's dive a little bit into some of the potential complications, which can range from stenosis to occlusion, aneurysm, dissection, pseudo, external compression. That could be your hand, which is obviously easily fixable. But sometimes it could be a hematoma that's compressing that access site, which is impacting the flow. It could be fluid collection. It could be hematoma. It could be one of these things. It could be many of these things. We also want to look at venous branches and note those because it's important to document that because if it's lower volumes going through the access site and we notice large branches, they may be a candidate for it to have those ligated to increase that volume through the actual access and improve their volume at dialysis and maintain the integrity of that site. So narrowing. Here you can see we've got what we see. We're working our way up more proximal towards the shoulder or towards maybe this is honored at a basilic. So maybe in the forearm, but we see what looks to be like a stenosis. So just with any elevation, any stenosis, we get a velocity pre, peak, and then post. And then here calculated the ratio. That's 7.8. That's considerable. So we get a grayscale. We can see that corresponding narrowing. So proximal to that stenosis, that most narrowed segment, and then just distal to that narrowing. And you can even tell just distal to this peak stenosis, some kind of stenotic components. It's not as smooth as we might see if there was no narrowing there. So external compression, we talked about that, but another source could be from an adjacent mass like that hematoma kind of pressing that access site. So inflow is really important. It will tell you that's one of the first things that we sample with spectral Doppler, and it can really tell you a lot about the overall flow within that access site. So here on the left, you see the inflow being sampled, and we know normal to be very low resistant, high volume. Well, we're starting to see here components of a higher resistant waveform. So here we can likely say, okay, I can expect some significant stenosis, something that's causing this to begin to normalize to a high resistant waveform instead of low resistant, like what we want. Over here to the right, we see the inflow completely normalized from multi-phasic waveform. So I would say this is likely occluded. And here is an example of just that. We have a completely multi-phasic high resistant waveform on the inflow. We sample the proximal anastomosis, which is just a little bit turbulent just because of that change in plane. And then here, sure enough, we see the occlusion, the echoes filling that lumen, and then we confirm it just as you always should with some power Doppler to make sure there's no stream sign, no nothing. It's just completely occluded. And we talked about presence of valves, the importance of noting that. If they are not lysed intraoperatively during placement, this could be the result. And over time, it causes an elevation and velocity that could impact the overall flow. So that's also very important to know in capturing gray scale as well. We've got an anterior and a posterior valve leaflet in that vein. And you can see it was their own vein because it's used to the basilic. Pseudoaneurysms are unfortunately just a common iatrogenic injury when you cannulate a site so many times. And so this is what they can appear like. And you want to try to get it in short axis and measure diameter, note the location. Here, you can see that we labeled number three. So that patient has had at least two prior to this one. And it's important to kind of note, again, how many the patient has so then we can track them in subsequent scans. Here are just some additional max diameters. And oftentimes, you'll see you take them in short axis or whatever angle you can open it up the largest and have the most accurate measurement. You'll want to turn, even though these are in gray scale, you'll want to turn the color scale down. So then you pick up any kind of low flow that's in there. And you want to make sure that you detect, play with your gray scale settings, your TGCs to make sure that you're not missing any maybe soft thrombus that's accumulating here that could eventually, you know, potentially become an embolic source. Here we have some hematoma. We have some synthetic graft with maybe just a mild fluid collection, major fluid collection. And this is really important to note and bring to the interpreting physician, the ordering physician's attention, because you don't want a needle cannulating through that and introducing any of that infection into that graft, which is then going straight through to the bloodstream. So you definitely want to make note of that and document that and relay that information. So here's some aneurysms, not pseudos, but just some aneurysms, which have some of that plaque formation, that soft thrombus. Don't blink. You could miss it. This one isn't too big, but it's notable. So you want to document it, location, the size, if there's soft thrombus, if there's any elevation. But keeping in mind, again, the patient could have one or many of these complications. Always document incidental findings. This may be post-operatively if you have some edema. It's important to kind of note if a patient has swelling and the access site is nice and patent, no suggestion of obstruction in the central veins or draining veins, but they have some edema, that may be a sign for the physician to investigate something else besides the patency of the site itself. Ports. It's important to note, this looks like to be a port or catheter in their jugular. If you see attached thrombus on that indwelling catheter, note it. It's important to kind of note that as well for when they remove that. It's just all part of their study, but then could impact their care plan. Always annotate everything. To remain compliant with accreditation, you don't want to omit, you don't want to leave an image out. You want to label the image accordingly as a placeholder, if you will. You want to note if it's technically difficult. Maybe it's post-op due to staples, incision, dressing, and you want to state what you're not able to visualize and why. And then most importantly, be aware of your lab's critical findings. Know what to bring to the physician's attention or your lead sonographer, your lead tech. So know your lab's policies, procedures, know your diagnostic criteria, know what findings are critical, and then your organization's pathway to relay these findings. It's really important to relay that information. And in conclusion, it starts with your preoperative evaluation. It helps determine the most suitable configuration for the patient, method of dialysis, a consistent and thorough interrogation of the entire AVF or AVG access that's necessary to identify those potential abnormalities. And as we talked about, it can be a lot, maybe one, maybe none, maybe several of them. Early detection through ultrasound, it can greatly assist in maintaining the integrity of that site long-term. Because again, these are the patient's lifelines. And with any care, the earlier it can be detected and tracked, the more chance there is that it can be intervened when deemed appropriate. And our role as a technologist is critical in recognizing these abnormalities. We're pretty amazing. So we can recognize stuff that, you know, others can't. Other departments may see it. They don't necessarily know. So what we do is pretty amazing. We can recognize this and report that information on to the appropriate person. Acquiring the necessary images, relaying those findings, but it's all in efforts to prolong the longevity of that patient's access site. So resources, vascular technology, vascular reference guide, that's where many of these illustrations came from. And this is my sweet Gracie. Hopefully I didn't put you to sleep like I put her to sleep preparing this. So thank you all. And I'd love to take any questions. Yes, we

imaging techniques

dialysis patients

arteriovenous fistulas

grafts

preoperative evaluation

stenosis

volume flow

patient outcomes

vascular technologist