Good afternoon, or good evening, everyone. Thank you for attending our webinar titled Dialysis Access, Field Evaluation Procedures. My name is Lori Lazansky. I'm the chair for the SBU eLearning Educational Committee. Before we begin, I have a couple of notes from the SBU office that I always want to share with you. This webinar will be recorded, and it's going to be available online for attendees through the SBU website at no charge. Please take a moment to familiarize yourself with the GoToWebinar program that we're using. Everyone should see a question section along the side menu of your screen, maybe near the bottom of the choices, just above chat. So please type in any questions that come to mind during the presentation. And at the end of the talk, we should have some time for discussion. Now, important to note, to receive your CMEs from this lecture, you need to wait for an email from the SBU office containing an evaluation. And then you should get that email in about 7 to 10 business days. When you get the evaluation completed, and your CME certificate will automatically pop up. So that's all I have for announcements. And so let's begin. This afternoon, tonight, we're honored to have Shannon York as our speaker. Shannon York is joining us tonight. She's the Principal Clinical Ultrasound Specialist and founder of Sky Vascular Consulting. She and her team members have provided training at over 150 national and four international sites, specializing in customized virtual and in-person education in the fields of transcranial Doppler and beginner to advanced vascular examination. Before consulting, Shannon worked at several labs in Columbia, South Carolina, after graduating in 2008 from the University of South Carolina with a bachelor's in science and psychology and biology. And then she earned her certificate in cardiovascular sonography from Midland Technical College. More recently, Shannon's done some work specifically with TCD exams and sickle cell. But over the years, she's worn many hats in the field, including sonographer, lab supervisor, and educator to sonography students and physicians now as a consultant. One of Shannon's personal commitments is to stay up-to-date on advancement throughout the world of sonography and to help her peers do the same. So in that spirit, she's going to speak to us about Dallas' Access STEEL evaluation procedures. Again, I encourage everyone to use the question feature, type in those questions that you have always wanted to ask the experts, and we'll get to them later on. So, okay. Now, Shannon, it's time for you to STEEL tonight's webinar. Good evening to everyone. I hope my volume is good, and we can continue on through the presentation. Thank you so much for the introduction. I've really, this topic I think of access procedures in general, dialysis access evaluations, I think is becoming somewhat of a hot topic. It's working its way into labs across the country. And I know from my personal experience that when I first started evaluating dialysis graphs and fistulas, it was a little bit of trial by fire. I would inevitably find myself in a situation where I thought it was, you know, one type of exam, and I find out there's a fistula or a graph, and so I started learning from there. And I know that when we first started doing dialysis access STEEL procedures, they were a little overwhelming and complicated. So the goal of this presentation is for me to maybe simplify it, give some background information, and then simplify the procedure process. So just to get us started, sorry, I had to get my slides running. I will leave this kind of summarized. I think I've just basically done that, is just making, giving you the background information that makes you a stronger investigator. There's a lot of investigative processes with evaluating dialysis access sites and, of course, you know, for STEEL. And then I think just I would like to make the whole process less intimidating, more if you do X, Y, and Z, then you're going to get to the result that the physician needs. And hopefully some of these procedure, I guess, workups that I'm offering will help you in your labs too if you need to adopt a procedure and adopt a protocol. I do not currently have any, sorry, no interests that would be, you know, any kind of complication or conflict here, so just wanted to disclose that. And as you already, Lori already said how the CMEs are taken, and you guys can claim those. So getting down to the content, I'm going to move through the slide show in a, hopefully you see my organizational process, but kind of an organized method where we start with an overview, just giving you the basic definition of what STEEL syndrome is. Then we move on to talking about the science of it. I'm not going to take a deep dive again because my goal is not to melt your brain tonight. It's just to educate you and give you some background knowledge. Give you, you know, as with anything that we're investigating, you know, it's good to know risk factors, differential diagnoses, you know, you can ask the right questions during your history taking. That's always, always helpful. I always, you know, for me it would have been helpful when I'm learning procedures or I'm evaluating dialysis access graphs if there had been, you know, patients carrying history around with them, but they don't, unfortunately. So a lot of times we have to do our investigative skills, investigative work, history taking. I'm going to circle back around, talk about it again, and then we're going to move into the meat and potatoes of it, which would be the workup, the procedures that we're going to be asked to do to specifically evaluate for STEEL, and that could be to include or exclude STEEL. So at the very end, I'm going to make sense of the results, hopefully lightly, give you some, I guess, interpretation result criteria, and then lightly touch on treatment options. So just starting with the overview, I think, you know, as our wonderful world of medicine continues to make advancements, we are seeing patients live older and older, and more chronic type issues, of course, are going to start to affect the population. So I just kind of wanted to start with, I think, the overview of why knowing dialysis, you know, workup on dialysis fistulas is so important to lives in general. It's not just a vascular exam. It's how a lot of these patients actually continue to survive. So you can see there's a large number of Americans on dialysis. This is just focusing on Americans. Of course, worldwide that number would be also, you know, quite large. And we expect for patients on dialysis to remain on dialysis for about five to ten years, hopefully longer. So it's very important that we keep, if the patient's receiving hemodialysis, that we keep a functional dialysis access. So we're going to talk about planning it. It starts from the beginning, the planning process, you know, how we can make sure that there's not an unaffected or unintended side effects such as steel, and, you know, what the decisions physicians make if steel does, it is diagnosed, and, you know, how we can maintain that graft. Because that's the ultimate goal is keeping the fistula or the graft patent and not having to ligate it and start over again. So to me, whenever I was first learning what dialysis steel was, it was quite confusing. So we're just going to start with basically the simple intro. When a patient has a graft or a fistula, there is a physiological amount of steel that's involved with it. So our focus is going to be on evaluating cases that are beyond that. So the flow is actually stealing, that the graft or fistula is in some way stealing flow from the hand that leads to, you know, deficiency of flow in the hand that can cause severe ischemia and, you know, worse cases, loss of fingers. You know, most severe cases, you know, we're trying to avoid that. So I'm going to refer to it as dialysis steel throughout the PowerPoint. There are different definitions, different, I guess, verbiages that it's referred to, but we'll just keep it simple, steel. So it is important, again, that the management of it is very timely, that we diagnose this early on and we get the correct diagnosis because now we have procedures that can actually keep that fistula patent. And allow the patient to be relieved of the steel syndrome. So I like this, this diagram, just I thought it was pretty simple, that, you know, we expect for a certain amount of blood flow that's coming into the arm to be diverted out through the outflow vein, of course. But, you know, we're looking at, when we're looking at steel, we're looking at a very minimal amount of flow getting down to past the fistula. So I think that in this, we're going to just, this particular presentation, we are not going to dive too deep into all of the aspects of hemodialysis fistulas. There's another great presentation coming up in another couple of weeks. So these will pair nicely. So that will talk more about, you know, a little deeper into some of the hemodynamics associated with like a normal fistula process, etc. So just kind of summarizing, because what I was saying is that we're going to focus specifically tonight on the malfunction of a fistula in which there is, the fistula is preventing enough blood flow to get down to the hand, the tissue in the hand to remain viable. So one thing that I guess I didn't realize when I first started, I worked in a very, very busy cardiovascular surgery practice. And I, I'm learning as we're doing trainings across the country that my, my plight was not alone, that we were managing, we were doing a lot of procedures. They were pretty complex, but we had a physician that came. He was wonderful. He changed my life. I learned so much from him. But he came from a very big organization and he brought a lot of these procedures with him. So I, you know, I had to learn how to do these procedures, especially the dialysis steel. And I didn't realize that there was, you know, the workups that I was doing were giving him more information than just say, yes, steel, no steel. Or if I do this thorough workup, I'm giving him all of the information, hopefully that he needs to exclude it, include it, exclude it and plan his surgical procedure. So the exams were rather, I thought, maybe a little lengthier sometimes. Why am I going through all these steps? Well, there was a good reason for it. And so I'm going to start kind of bringing this concept into the different types of things that can cause hand ischemia. And then I'll tie it back together at the end after we get through the procedures and we'll learn how those different types of ischemia are diagnosed through our exams. And then allow them to know which procedure will help fix the problem. So I thought this chart, it's busy. We're just going to kind of kind of skim over it. I just wanted to say very sorry. I'm trying to get one of the pop ups out of the way so I can see a little bit better. To break it down very simply, we're going to start with the top type A and that would be a steel, a true steel syndrome where the fistula itself is pulling too much blood, too large of an orifice. The surgeon did a great job, made it, made it too well. So we're actually pulling too much blood flow and we need to dampen that down. We kind of we refer to that as maybe the true steel syndrome. So the fistula itself is causing that blood flow to kind of be siphoned out of the arm from the hand. Another reason for ischemia in the hand in the presence of a fistula would be that we don't have enough flow coming into the arm. So we have some kind of proximal stenosis. So the flow that's actually getting into the arm is not very pressurized and it's not pressurized enough to make it past the fistula. It just doesn't stand a chance. It's being pulled out through that high resistant or that low resistant fistula bed. And the last would be that the patient has distal disease. So we have a fistula somewhere in the arm and distal to that. We have chronic chronic hardening of the arteries, narrowing the arteries in the radial ulnar. And we just simply don't have enough pressure to get through that high resistant vascular bed. Basically, that that disease is pushing back. So any one of these can cause ischemia in the hand in the presence of a fistula. We can have a combination of these things going on, but they're all treated slightly differently. So it's really important to know if what we're looking at as far as where the pressure gradient is and where we're losing that pressure. I will say, you know, all of our exams eventually probably pre-surgically would be confirmed with, you know, with other imaging. But the value of doing the physiologic testing is that it directly tells the physician about those pressures, you know, where the pressure gradient is. And the pressures, of course, also allow us to know what's going on in the micro circulation and the collateral flow, et cetera. So. Pop up in my way, I apologize, just kind of summarizing and don't mean to make it overly complicated, that the dialysis deal syndrome is often characterized by excessive blood flow through the AV fistula conduit. However, it's not always the case. You know, there are other factors that can contribute. So we need to know a little bit about the circulation under, you know, behind the scenes. So the role of collateral circulation inevitably is very important. We can have a patient, for instance, that has a very high flow going through the fistula. However, their hand is still perfused because they are getting enough flow through collateral circulation. So that's one another benefit of the physiologic testing is. You know, we could be misled if we're just doing duplex and we're getting a really high flow volume and we're getting reversal of flow in the vessels distal to the fistula. But if we are able to actually get those pressures down at the very bottom, at the very distal point in the fingers, then we can prove that there's good collateral circulation and the patient may not be in a ischemic state. So just a light understanding of how fistulas and grafts and collateral vessels work together is important. Again, I think that's going to be tied together very nicely with the other webinar coming up in a couple of weeks. And then we are also going to have to take into account that things can be exacerbated. The steel can be exacerbated by chronic occlusions, both proximal and distal. So somebody that doesn't have a very high flow volume in the fistula, if we add in a little chronic arterial disease into the mix, then we can actually result in steel with lower flow volumes. Fistulas and grafts that involve the brachial tend to be a higher prevalence of steel, and they actually tend to cause more severe ischemia. And the reason being is that in most situations the brachial is actually feeding both the radial and the ulnar, so an issue there can actually draw all the blood away from the hand versus a radial fistula, which typically of a radial fistula, if you image, you'll have retrograde flared distal to that, but there will be enough collateralization through the ulnar to actually perfuse the hand, so a little higher prevalence with the brachial fistulas. And so I'm gonna actually just kind of move, I think it'd make a little sense to kind of move to this slide here. So there are certain stages, everything usually comes in stages. The initial stage typically of steel is that we'll have retrograde diastolic flow, however, the patient will not be symptomatic. So if we're doing a duplex examination and we see two fro flowed distal to the fistula, that's not a reason to be alarmed by any means, that's a normal finding in most cases. The patient will present, typically when we start to see the steel onset, they'll actually have symptoms in the hand, that'll be numbness, pain. A lot of times it's exacerbated during dialysis, so that's important to note. And just a cold feeling in the hand, it usually doesn't turn acute right away, there is that process that build up. Pain at rest, so chronic pain, just incurable pain is usually, I guess, what prompts the individual to come in and really say, okay, we've got to evaluate this. And then unfortunately, the last stage would be tissue loss. It's a balance for surgeons for sure to have to decide at what point, is the something that they can maybe power through or they can, it's symptomatic, but it may not be something that they're not ready to intervene. Because again, the last thing that we wanna see is that graft be ligated and any subsequent surgical procedure to graft or fistula is a risk, that there may be a complication, we may lose flow to it. So you'll see patients that come in in different stages, I'll actually get to that in just a second. So, the timing of the presentation is important as well. And taking just these background histories, a lot of comorbidities exist, we know that with people that are typically on dialysis, they can actually exacerbate the problem for sure. Diabetes have, excuse me, hardening of the arteries, so a higher distal resistance. Coronary disease, just generalized atherosclerosis. Peripheral vascular disease, again, would be inflow disease, outflow problems. We also know that the presence of fistulas in the arm, they've had multiple revascularizations that we just are gonna be spotted with occlusions and disease already. So, we're kind of fighting an uphill battle from that point. And typically, individuals that have had steel before, tend to be prone to it again, even if there aren't chronic occlusions, may just be kind of the underlying lack of collateral flow. Another thing that I've noticed, is just kind of talking off the PowerPoint, that there's, to me, there tended to be kind of two patient populations that I would be more concerned with, and that would be to the younger, healthier patients with higher cardiac output, and they have larger veins. So, they tend to have larger anastomotic sites. So, that large vein size, good flow is working in their favor in some aspects, because we can get, we have an easier time getting fistula and graft in, but then on the other hand, sometimes they can be almost placed too well, and then there's the patient population who has had multiple grafts and revascularizations, and they do have all those chronic occlusions and narrowing of the arteries. So, those two tend to kind of do very ends of the spectrum, but present with a lot higher prevalence of steel. A lot of times, this is just coming from my experience too, when patients are brand new to dialysis, they tend to, you know, they've never experienced it. They're unused, they're not used to that initial change in flow in their hands, and a lot of times that flow is bothersome, you know, just that physiological steel is bothersome to them at first, but it'll level out a little bit. So, sometimes it's just they're not used to having the fistula or graft, so physicians will definitely proceed with, you know, let's check it out, let's just make sure we're exploring it, and try to encourage them, you know, to power through that initial phase while the graft is maturing and they're first on dialysis. Sometimes there can actually be some disruptions to the nerves, different, you know, other things that may cause arm and hand pain during the surgery, and then just generalized ischemia. So, again, the onset of it is, I think I've already kind of touched on that, it's with, it tends to be more of like, we see the onset very early on, or a little bit later, you know, with patients that have had poor, they have poor circulation in general. The grafts tend to present a little bit earlier with TruSteel than the fistulas. So, I think I would just summarize everything that I was saying that is, history taking is very important, you know, find out when the fistula is placed, you know, obviously you'll want to find out about their comorbidities, and just document all of that very well. And I, these are just some images, so this is actually something I, you know, worst case scenario, but you, when a patient's hand does start to experience, you know, gangrene, et cetera, these types of symptoms, the physician's still facing a challenge to decide, you know, what do we do? Would we rather have to, you know, lose part of the fingertip, or would we rather have to try to ligate the graft? So, it's a tough challenge, and they're going to research it really well and make the best decision. This is just, I thought this was a powerful image, just showing how much, you know, what the lack of flow down there in the presence of steel. So, almost getting to the procedure part, I promise. I just wanted to reiterate this, this is, I think, an important aspect of everything, and we're not going to talk about the planning process in depth, but I think any surgeon will say that, you know, the more information, the better that planning, that mapping, that arterial mapping is, there's some more information they have to go on when they go into surgery, and the lower prevalence of a complication such as steel. So, good surgical, you know, doing that work up on the front end and understanding the information that the physicians really need to know on the front end is just as important, you know, with preventing steel. So, the arterial and venous mapping, having that done and having that done by a trained individual within a certain timeframe, we generally want to repeat it if it's been about six months or more, or we feel like there's been a significant change. We want to be really sure when we're doing our work up that we document chronic occlusions, you know, be thorough with that, let them know, you know, if we're seeing inflow disease, if we're seeing, you know, disease in the distal arteries, that's really important. Anatomical variations, you know, something like a high bifurcation of the brachial is very important that can make or break steel syndrome. So, be sure to be really thorough with documenting that. Of course, any previous graphs, documentation, and then some facilities, and this is just part of the work up, is that pre-operative evaluation of the palmar arch. That'll be up to your facility, and it may be case-by-case. So, now we're getting down to the testing procedures, and my goal, hopefully I haven't confused anybody too much at this point, is to break this down in a simple workflow. So, if we, you know, I'm not suggesting that every facility, you know, break out and do all of these if you already have a well-oiled program, by all means, but, you know, if these are, if you need to adopt some protocols and kind of understanding of why, then this is what the overall goal of this portion would be. So, the physiological exam, I think, is extremely important. It gives us kind of that, what we were referring back to in the beginning, you know, that it could be an inflow issue. It could very well be that the patient maybe has enough flow getting into the arm, but it's not making it down to the hand. So, we'll see that pressure gradient, and it also gives us part of the dialysis deal results interpretation is comparing proximal to distal arm and then also from affected to non-affected. So, this just gives us a good workup. It lets us know also about that collateral flow that the duplex may or may not allow us to know. And we're going to talk very specifically about the steel compression maneuver, and so I think that's what is being worked into labs more often, so I just want to make sure everybody's comfortable with that and, you know, we can make it so that it's not a one-hour drawn-out long procedure, that it's just really simple and concise. They'll offer some advice on that and also on the reporting. The duplex evaluation, so that's still going to be, in most cases, that's still going to be part of this workup. There are specific things that physiologic evaluation will tell us, and then there's specific things that the duplex evaluation will tell us. So, I think they pair well together for certain reasons, but the protocols that I'm going to suggest to you today, I think you could get all of these done in about an hour, maybe an hour and 15 minutes, and you may not need to do all of these. There'll be, you know, kind of a decision tree of when we proceed on to doing each, and, of course, your physician will let you know. They'll say, well, today, you know, I just need to know this, and we're going to do this portion of it, so you don't have to do all of this every time, and certainly these are just geared towards evaluating for steel, rolling it in or out, and then saying, okay, this is the level of the steel and the reason, so you'll have the duplex evaluation on its own sometimes, like if you're assessing a fistula for maturity, you're just doing a simple, you know, patency check. So, I'm going to just talk again at the very end about, like, the rationale for doing both so you don't think we're just, you know, out to give you a long day, and then what the results mean. So, I'd like to suggest that, especially, you know, in situations if there's not, like, a close communication maybe between you and the physicians or the performing lab and the ordering physician that we do a more thorough exam. That way, when the patient goes in to see their physician, they have all of the information that they need. They don't need to circle back around. So, this would start with just doing an upper physiologic arterial exam, and that would be my recommendation would be doing the three levels. So, you would do the brachial, the forearm, and the wrist, and we may or may not, that's your lab's policy as to whether we would put a cuff over the outflow vein of the affected arm. I have worked in labs where that's okay to do just once, barring any side situations that would be contraindicated, but we certainly will try to get as many levels as we can. So, we would get, basically, a baseline PVR in the upper arm, lower arm, and the wrist, and that'll tell us, basically, you know, if we do have loss of flow that's significant, where that's occurring, at what level, and then baseline pressures. So, that would be getting a pressure in the brachial artery, using the brachial as the source artery, so just making sure that we're not kind of listening on the other side of any occlusions, et cetera. We'd get a radial artery forearm pressure and then a radial artery wrist pressure, so just testing the patency of, you know, and they're testing for a pressure gradient in the radial all the way down, the same with the ulnar, and then document the Doppler signals and such, and then, of course, at the very end, because we are, you know, with the dialysis steel especially, we want to know how much flow is getting down to the hands. So, the digits are the bottom line, so we'll obtain digit pressures here, and if we complete this test, I may come back to that actually in a second. So, if we get through doing that full workup and we notice that the goal, you know, is to kind of say, okay, we don't need to go forward. We may not. Actually, I'm sorry. I'm going to skip to this very quickly. The full physiologic workup, if we get through that examination and we notice that there is a reasonable amount of flow in the presence of the fistula getting down to the hand, so that's about 75% of the flow coming in is getting down to the hand, that's actually expected for someone that has a fistula, and at that point, we can say, okay, we don't necessarily need to move on. We're good. We've excluded that the patient has a vascular issue. It also just gives us that full workup again of where the pressure gradient is, you know, if that's occurring, if there's an inflow problem, if it's down in the hand, et cetera. I'm just going to come back here. Sorry for skipping around a little bit because I just want to make sure I'm not suggesting that we take pressures over outflow veins or fistula. Again, this would be up to your lab or up to the surgeon. We definitely do not want to take a pressure over a fistula or graft or outflow vein. Of course, we'd try to be over the outflow vein if it's new, relatively new, while there may be a low flow volume or if aneurysmal portions are present. So just kind of wrapping that up, I know I kind of dumbled around a little bit. I apologize. The purpose of the screening exam would be to determine if there is a physiologic steel in the hand, so that would just be alone to the graft or if the graft is stealing, which would be larceny. So it lets us know whether we need to proceed on to further testing. It gives us the level of ischemia. It gives us a comparison between the affected and the non-affected arm, and then it gives the surgeon just kind of a full workup. So should we, if the baseline tracings, again, are within normal limits in that full physiologic workup, then we would be good. We would say, come back to the physician and say, we've done this workup and the digits are fine. So at that point, it may not even be necessary to proceed on at all. They may have to say, okay, patient's not suffering from steel. They may have a neurogenic component, something else. So it gives us a lot of data with that one initial test. If our baseline tracings are considered to be abnormal or our baseline full physiologic workup, so that means that we do have, you know, we don't just have a physiologic steel that we have something greater than that, then we would move on to this next step. So just clearing that up, just making sure I'm being clear, is that to see about 25% reduced flow in the affected hand compared to the non-affected hand. So the hand with the fistula just has about 25% reduced pressures, and that would be amplitude and PPGs as well, compared to the unaffected hand, that's normal. So we would let the physician know that that's a normal finding. He should be able to use that full workup and look and make those deductions for himself. If it's normal, if your lab deems that it's just best to go ahead and proceed on to the second part of this test, which would be the compression maneuvers, it shouldn't take much, much longer. So I'm just actually gonna freeze the image here and just kind of talk about my initial experience with doing the compression maneuvers. And so we do, ideally, when we're evaluating steel, we want to evaluate all five digits. Your lab may have other policies. It's usually, if we're not doing all five digits, it's because of, it's just, it's a lengthier exam if we have to do digit by digit. So there are certain systems now that where you can do five digits at a time. However, I, whether we're using, doing it digit by digit, or we're able to do all five digits at once, I strongly recommend that we do all five digits. Just getting into the, you know, the Palmer arch and all of the different possibilities of complete Palmer arch, collateralization, et cetera. Somebody can experience steel in part of the hand. And part of the hand can be really a skin, and compromised versus the other part. So we really do need to get that full workup. Sometimes it can even just be affecting a single digit. So just kind of summarizing up until this point, whether we have done the full workup or not, you know, whether the lab just calls for us doing just this compression maneuver, we're going to need to get readings on both the affected hand and the unaffected hand. So we're gonna take PPGs, and we're gonna take blood pressure cuffs, and we're going to evaluate the digits on both the affected hand and the unaffected hand. So we go ahead and we get cuffs wrapped around. I usually will start with the hand that's unaffected first, and we'll go ahead and get cuff wrapped around each finger. We'll place the PPG sensor on the finger, and we will get a baseline PPG reading on the unaffected hand and then baseline pressure. So I'm gonna just move forward. I'm gonna say that we have a fistula on the right side. So I will get just baseline PPG readings on all five fingers on the left, baseline pressures. And then we'll go ahead and move everything over to the affected hand, so the right hand, and we'll get all the cuffs on, and we'll put the PPG sensors on the tips of the fingers, and we'll take pressures and PPG readings on the hand at rest. So just laying the hand in the lap, and then we will compress. I suggest, me personally, the way that we were taught to do it is to, instead of compressing right over the fistula or the graft, is just to compress over the outflow vein about two finger lengths distal to the anastomosis, the arterial anastomosis. This should, if you're close enough to the fistula, you're going to occlude the flow in the fistula, so it should be just as effective. So just to summarize what I've said thus far would be that we're going to do PPG and blood pressure readings on the hand that doesn't have the fistula, and then we're gonna move over and do PPG readings and pressures on the hand with the fistula, and then we're gonna be occluding the outflow vein or the fistula, and basically taking, for a brief moment in time, we're gonna take the fistula out of the equation. So what would happen to the hand? What would the hand be doing if the fistula wasn't there? And so if the fistula is the true cause of the steel, so it's basically saying if that fistula graft is pulling too hard, then we take it out of the equation. Then what should happen is we should see, I'm gonna move to this image first, we should see a normalization. So basically the flow kind of comes back to the hand, and so that tells the physician right there that despite flow volume, all things aside, that the fistula itself is what's causing these pressures to be so low. So just kind of reviewing what this report is showing us is we had a fistula in the right side, the right hand, and we're worried that they're steel. So we started over here on the left. We see what normal looks like. We get the pressures over here on the left, the digit pressures. We do a baseline reading on the hand with the fistula, and we see a considerable difference. These PPGs are considerably reduced, and the pressures here are about 50% or greater reduced compared to the affected hand. We do the compression. So right now we're doing a compression, taking the fistula out of the equation, and look, we have normalization, and we have normalization of the pressures. So that would indicate to the physician right then and there that the fistula itself is steeling. These, I think maybe I would just kind of leave this kind of simple, because I don't want to get lost in the process here, but a results indicative of true steel, so graft is pulling too hard, basically would be absolute pressures on the digits of the affected hand are half or more of what they are on the unaffected hand. And then we have a significant difference in the pressures in the hand as compared to the proximal arm. And then we take all of that, and we prove that the fistula itself is the cause, and we do that by compressing the outflow vein and seeing that normalization. So I kind of will lead you with this. Again, my goal was to make it not so confusing, and I want to simplify it. I think maybe I went in a little farther than I should with some of that explanation, so I'm just going to kind of back up here. We have the patient that comes in with symptoms that are worrisome of steel, so painful hand, maybe not quite at the gangrenous stage, but we have a patient that comes in with all the symptoms that would check the boxes for steel. We do the physiological screening exam. If the physiologic screening exam shows us that the hand that is on the affected arm with the fistula, that it's receiving 75% or greater of the amount of blood as compared to the contralateral arm that's considered normal, we don't need to go any further. We do that full workup, and we see that there is ischemia in the hand. Then we would go ahead, and we would do the physiological steel compression maneuver, and we'd either get a normalization, which would say, okay, it's the fistula pulling too hard, and then we'd continue on to the duplex just to document the flow volume for the physician, note any arterial occlusions, et cetera. If we do that steel compression maneuver and it does not normalize, we'd still go on to do a duplex, but that would basically tell the physician at that point that there's some type of either lack of collateral flow, chronic arterial occlusion, inflow disease that's causing the hand to be ischemic. So I would say the takeaway here would be we just follow the same steps every time, and we are giving the physician this information. Whether we intend to or not, we are telling him more than likely where the problem is and what'll help fix it. I think in most cases, we're still gonna do a simple duplex, and I know looking at this, this is probably like, oh goodness, another step. This is really simple to do, especially once you've done a few. If we take out this middle step, the anastomosis, we're basically just doing a quick, simple upper arterial duplex. So we're gonna assess grayscale color doppler of the inflow arteries, the subclavian, and going down here into the brachial, make sure we don't see any stenosis. Then we would do the same. We'd get to the, after we get past the fistula, we do grayscale color doppler of the distal arteries, so the radial and the ulnar, and then we'd evaluate that anastomotic site. So we would just do some simple dopplering before the anastomotic site, in the anastomotic site, and after. And this is just basically gonna, again, gonna be additional information for the physician. I wanted to very specifically, and we're almost wrapped up with this portion, so just talk about how we obtain flow volumes, because I think that that was, it's a question. I've heard it come up in some of our trainings, and I would say my recommendation, the way that we did it, and it worked very well, would be to take your flow volumes within the brachial artery. You do need to have a very straight, linear portion of the vessel, which is very hard to do in the actual fistula. So this flow volume, if we take the flow volume in the brachial artery, and we'll take three points, just to have kind of an average flow volume, and add those together, and we would basically average these together here. I'm gonna, I actually noticed I made a boo-boo here. So disregard this here, and focus on this up here. So we would take the flow volumes by taking three different points in the brachial artery, averaging the three together, and then subtracting 100. That should give us the flow volume getting into the fistula. So we would do that whether we are, the fistula is in the distal arm or the proximal arm. This is gonna show us more or less the flow that's coming down through the fistula. We'd also, of course, when we're doing the flow volumes, we'd wanna make sure that we're documenting areas of stenosis, occlusion, the anastomotic site of the diameter of the arterial anastomosis. And we'd also just wanna make special note of this flow volume. So just to give you a quick glance of what would be normal, an abnormally low flow volume here would be outside of the realm of what we would be concentrating on with steel. We're looking at more of these excessive flow volumes here. So if we give this information, the information on the flow volume in conjunction with everything that we've done with the fistula steel physiologic test, it'll let the physicians know that basically what's causing the issue. Give me just one second. I am sorry, I got myself turned around a little bit. I apologize. So I don't wanna drive you guys, drive it too far home with all of these details. We're just, when we're doing a duplex evaluation, we wanna make sure just, I don't know if everybody's well acquainted with how to get flow volumes, but we would basically open up the sample volume to the width of the arterial wall so that we're measuring all of the flow that's going through the artery. We would use the midbrachial artery that I'd highly suggest that. It gives you a good place to just focus on it. You'd get a good diameter there. Take three measurements in the midbrachial artery, add them together and divide by three. When we're looking for retrograde flow, distal to the fistula, we wanna make sure that we don't invert signals, that we make sure that, that can be confusing sometimes. So we just wanna make sure that we're documenting true reversal of flow, those anatomical variations, et cetera. And so I, this is an example of a true retrograde flow here. And I know that we're kind of running through time. So I'm just gonna skip here. We're running out of time. What have we done throughout all of this? We've let the physician know by doing that full physiologic workup, by doing the outflow vein compression procedure, and then doing that supplemental arterial duplex that gives flow volumes, and it assesses for arterial occlusions. And it also gives us the, whether flow is retrograde or antergrade. We've basically given the physicians all of this information that they need. And I'm just gonna tie it to this chart here. It lets them know how to proceed with the treatment. So they really appreciate this thorough workup because it would basically let them know if we're dealing with an issue where there's inadequate inflow. So we're not, we don't have enough flow getting into the arm. Therefore, it's not gonna make it by the fistula to the hand. Whether we're dealing with a fistula that's pulling too hard. So that's where that flow volume comes in handy. Or whether we're dealing with a chronic disease in the hand that's not allowing enough flow in. And I may just kind of, I guess, lightly talk about this as we're running out of time here would be some of the revascularization procedures. This drill procedure, actually, as you can see, they ligate the vessel here and just basically import flow down. That's a common procedure. I think it's one of the more common procedures. A revision using distal inflow. So this basically takes flow. This takes flow, allows it to get down into the hand. And then we have flow coming out into the outflow vein. These admittedly look pretty complicated. So I don't wanna make everyone's head spin. But I would say maybe that, and this I think will be available for a short while for you to review. These distal, these distinctly different procedures are all based on the information that we're handing the physicians through our testing. So the testing is extremely important in letting them know which vascularization procedure is gonna be the most effective for the patient and alleviate the steel symptoms and not exacerbate them. Just very lastly, ligation is the last resort. So we would be giving them all of this information as best that we can to allow them to make the right surgical procedures so that ligation isn't possible. Excuse me. So that is basically, I'm sorry, my voice is running out, but that was kind of the overall, the importance of the vascular ultrasounds. Excuse me. From the beginning down to the diagnostics and then the surgical follow-up. I lost my voice. Sorry. That's okay. You're doing well. We do have questions, Shannon. Thank you for that presentation. We could try to get a couple of them and then if there's time, I'd love if you went back to that duplex slide you had about steel. But let's ask a couple questions first. So one of the questions that came in was, do you still consider it a steel if flow is retrograde in the radial artery but then becomes antegrade in the distal half of the forearm? Say that one more time. If it's a brachial fistula graph, correct? Yeah, it's not specified, but they're just asking, say you get retrograde flow in the radial artery approximately but then it becomes antegrade distally, like in the distal half of the forearm.

retrograde flow

radial artery

antegrade flow

collateral circulation

dialysis steal syndrome

fistula influence

duplex findings

perfusion assessment

arterial steal symptoms