- Thank you to the host for inviting me to speak again this year. I don't have any disclosures other than the fact that I'm a co-author on the paper that's being presented, but got no reimbursement for that. So I flew in from Chicago on Thursday
during your first snow, for those of you who live in New York, and this was the afternoon I'd made it unscathed on my flight, everything subsequent to that from Chicago got canceled, and I got here
and it was a lot like a Chicago winter. Lots of snow, women wearing impractical shoes, but there were two things that were missing: snow plows and salt. Where's your salt game? I mean I don't understand New York,
there was nothing. So I claim that Chicago has a better snow clearing game than New York does, - [Man] And weathermen. - And weathermen, that's right.
Okay. I'm in charge with giving you some information about a publication that we did this year on the DOPPS. And for those of you who are unfamiliar with the DOPPS, just a quick background.
The DOPPS Outcomes Practical Patterns Study started in 1996, and it's resulted in a series of prospective studies from more than 20 countries around the world. It includes a cohort of Hemodialysis, CKD, and PD patients,
which now totals 70,000 patients. And its principal goal was to identify modifiable clinical practices to improve patient outcomes. And just to give you an idea of which countries are represented,
those in the blue, each wave of the DOPPS has incorporated a broader span of countries, and the most recent wave included China and many countries in the Middle East. So it's quite representative of what's going on around the world.
So we elected to look at issues related to AV fistula location and use, and compare those to countries in Japan, Europe, and New Zealand, and looked at a prospective study that spanned between 2009 and 2015.
It involved over 4,000 fistulas, about 1,000 grafts. And in order to get some trend analysis, we used DOPPS data that was collected between 1996 and 2015. And we looked at three specific outcomes:
AV fistula location, time to first use, and continued use. Some key findings here are that, for any of you who've traveled to Japan and spent time with dialysis patients, it's impressive.
This dark color represents lower arm fistulas and this lighter color represents upper arm, and you can see here that over time, as the DOPPS gone successively from the 1990s through 2015, Japan has maintained principal use
of lower-arm fistulas. When we go to Europe, what you can see is that there's been a slight decline in lower-arm fistulas from about 77% of those in the cohorts down to about 66%.
But when we get over to the U.S., we find that interestingly, there's been an inversion. Where previously, there had been lower-arm fistulas, in the 1990s, this is now switched to upper-arm fistulas,
despite the fact that the U.S. has the lowest mean age of those people that are undergoing dialysis. And interestingly, among those patients that we consider to have the lowest risk for fistula maturation failure,
namely young men, less than 50% of U.S. males less than 50 years of age, had fistulas located in the lower arm in our most recent DOPPS cohort compared to 73% in Europe and 98% in Japan. And the implications of this are two-fold.
Principally exhausting AV access sites and then complications that can be related to upper arm high-flow access. So just quickly, I want to touch on successful use, which differs internationally.
You can see here that for those patients that had continuous use for more than 30 days, Japan had 87% of its cohort who maintained this, while the United States, 64% of its cohort did. And these numbers are similar to USRDS reporting.
Japan's AV fistula use was more successful, or, I'm sorry, the AV fistula use was more successful in the upper arm versus the lower-arm fistulas in the U.S. and in Europe, but not in Japan. It didn't seem to matter
whether it was upper or lower arm, they still seemed to work equally well. Interestingly too, time differs in terms of cannulation. The mean days to AV fistula cannulation in Japan were only 10 days,
compared to nearly three months for the United States. And when they looked at median days to graft cannulation, similar pattern existed, Japan had six days to cannulation
whereas the U.S. had 30 days. So what are some possible differences for these? There're many. But Fistula First is obviously the big, the big one that comes to mind because its implementation mirrors
the timing and the trend, the shift in upper-arm fistulas in the U.S. There's also a known high AV fistula maturation rate in the United States, which may discourage surgeons
from placing lower-arm fistulas initially. There are a limited number, in my view, of experienced and skilled surgeons that have a broad fistula repertoire in the lower arm, lack of widespread pre-operative ultrasound
vessel mapping, and lack of attention to vessel preservation. So what are some possible reasons for greater time to use in the U.S.? I think that it's largely superficialization procedures that are needed
because of body habitus. There's some hesitancy around cannulation segments, maybe being limited or deep. Nephrologists really don't know how to examine and access,
and I'm one of, I'm a Nephrologist, I can say that. And then lack of cannulation expertise in a dialysis unit. So how does Japan do it? Despite an older mean age for dialysis,
there's a much lower median blood flow for dialysis. They use a 200 pump speed, whereas we use 400 to 500 millimeters per minute pump speed. And this largely achieved because they, many times, have a smaller body weight,
but they also accommodate longer treatment times and smaller gauge needles. And they limit their surgeons to those that really have experience. So for visual learners out there, this is the summary of what I've said.
The percent of fistulas in the lower arm in Japan is 95%, U.S. is 32%. The number of days to a successful fistula cannulation is significantly longer in the U.S. And some takeaways are three, then I'm done.
Patients don't necessarily require high-flow fistulas, just a modified dialysis prescription, and this can come about through an expansion of home and nocturnal dialysis.
Improvements are needed for surgical expertise and training. And, in fact, the Endo AV fistula, which you'll be hearing about later today, may, in fact, increase fistula usability and reduce time to cannulation
in certain patient populations. And because I'm the President of ASDIN, I invite all of you to come to our February meeting, escape the cold, it's in Atlanta this year. Thank you for your attention.
- Thank you, Larry, thank you, Tony. Nice to be known as a fixture. I have no relevant disclosures, except that I have a trophy. And that's important, but also that Prabir Roy-Chaudhury, who's in this picture, was the genesis of some of the thoughts that I'm going to deliver here about predicting renal failure,
so I do want to credit him with bringing that to the vascular access space. You know, following on Soren's talk about access guidelines, we're dealing with pretty old guidelines, but if you look at the 2006 version, you know, just the height--
The things that a surgeon might read in his office. CKD four, patients there, you want a timely referral, you want them evaluated for placement of permanent access. The term "if necessary" is included in those guidelines, that's sometimes forgotten about.
And, of course, veins should be protected. We already heard a little bit about that, and so out our hospital, with our new dialysis patients, we usually try to butcher both antecubital veins at the same time. And then, before we send them to surgery
after they've been vein-marked, we use that vein to put in their preoperative IV, so that's our vascular access management program at Christiana Care. - [Male Speaker] That's why we mark it for you, Teddy. (laughing)
- So, you know, the other guideline is patients should have a functional permanent access at the initiation of dialysis therapy, and that means we need a crystal ball. How do we know this? A fistula should be placed at least six months
before anticipated start of dialysis, or a graft three to six weeks. Anybody who tells you they actually know that is lying, you can't tell, there's no validated means of predicting this. You hear clinical judgment, you can look at
all sorts of things. You cannot really make that projection. Now there is one interesting study by Tangri, and this is what Premier brought to our attention last year at CIDA, where this Canadian researcher and his team developed a model for predicting
progression of chronic kidney disease, not specifically for access purposes, but for others. They looked at a large number of patients in Canada, followed them through chronic kidney disease to ESRD, and they came up with a model. If you look at a simple model that uses age, sex,
estimated GFR from MDRD equation and albuminuria to predict when that patient might develop end stage renal disease, and there's now nice calculators. This is a wonderful thing, I keep it on my phone, this Qx Calculate, I would recommend you do the same,
and you can put those answers to the questions, in this app, and it'll give you the answer you're looking for. So for instance, here's a case, a 75-year-old woman, CKD stage four, her creatinine's 2.7, not very impressive,
eGFR's 18. Her urine protein is 1200 milligrams per gram, that's important, this is kind of one of the major variables that impacts on this. So she's referred appropriately at that stage to a surgeon for arteriovenous access,
and he finds that she really has no veins that he feels are suitable for a fistula, so an appropriate referral was made. Now at that time, if you'd put her into this equation with those variables, 1200, female, 75-year-old, 18 GFR, at two years, her risk of ESRD is about 30%,
and at five years about 66%, 67%. So, you know, how do you use those numbers in deciding if she needs an access? Well, you might say... A rational person might say perhaps that patient should get a fistula,
or at least be put in line for it. Well, this well-intentioned surgeon providing customer service put in a graft, which then ended up with some steal requiring a DRIL, which then still had steal, required banding, and then a few months, a year later
was thrombosed and abandoned because she didn't need it. And I saw her for the first time in October 2018, at which time her creatinine is up to 3.6, her eGFR's down to 12, her protein is a little higher, 2600, so now she has a two-year risk of 62%, and a five-year risk of 95%,
considerably more than when this ill-advised craft was created. So what do you do with this patient now? I don't have the answer to that, but you can use this information at least to help flavor your thought process,
and what if you could bend the curve? What if you treated this patient appropriately with ACE inhibitors and other methods to get the protein down? Well, you can almost half her two-year risk of renal failure with medical management.
So these considerations I think are important to the team, surgeon, nurses, nephrologists, etc., who are planning that vascular access with the patient. When to do and what to do. And then, you know, it's kind of old-fashioned to look at the trajectory.
We used to look at one over creatinine, we can look at eGFR now, and she's on a trajectory that looks suspicious for progression, so you can factor that into your thought process as well. And then I think this is the other very important concept, I think I've spoken about this here before,
is that there's no absolute need for dialysis unless you do bilateral nephrectomies. Patients can be managed medically for quite a while, and the manifestations of uremia dealt with quite safely and effectively, and you can see that over the years, the number of patients
in this top brown pattern that have been started on dialysis with a GFR of greater than 15 has fallen, or at least, stopped rising because we've recognized that there's no advantage, and there may be disadvantages to starting patients too early.
So if your nephrologist is telling I've got to start this patient now because he or she needs dialysis, unless they had bilateral nephrectomies that may or may not be true. Another case,
64-year-old male, CKD stage four, creatinine about four, eGFR 15, 800 milligrams of proteinuria, referred to a vascular access surgeon for AV access. Interesting note, previous central lines, or AICD, healthy guy otherwise.
So in April 2017 he had a left wrist fistula done, I think that was a very appropriate referral and a very appropriate operation by this surgeon. At that time his two-year risk was 49, 50%, his five-year risk 88%. It's a pretty good idea, I think, to get a wrist fistula
in that patient. Once again, this is not validated for that purpose. I can't point you to a study that says by using this you can make well-informed predictions about when to do vascular access, but I do think it helps to flavor the judgment on this.
Also, I saw him for the first time last month, and his left arm is like this. Amazing, that has never had a catheter or anything, so I did his central venogram, and this is his anatomy. I could find absolutely no evidence of a connection between the left subclavian and the superior vena cava,
I couldn't cross it. Incidentally, this was done with less than 20 CCs of dye of trying to open this occlusion or find a way through, which was unsuccessful. You can see all the edema in his arm. So what do you do with this guy now?
Well, up, go back. Here's his trajectory of CKD four from the time his fistula is done to the time I'm seeing him now, he's been pretty flat. And his proteinuria's actually dropped
with medical management. He's only got 103 milligrams per gram of proteinuria now, and his two-year risk is now 23%, his five-year risk is 56%, so I said back to the surgeon we ligate this damn thing, because we can't really do much to fix it,
and we're going to wait and see when it's closer to time to needing dialysis. I'm not going to subject this guy to a right-arm fistula with that trajectory of renal disease over the past two years. So combining that trajectory with these predictive numbers,
and improved medical care for proteinuria I think is a good strategy. So what do you do, you're weighing factors for timing too early, you've got a burden of fistula failure, interventions you need to use to maintain costs, morbidity, complications,
steal, neuropathy that you could avoid versus too late and disadvantages of initiating hemodialysis without a permanent access. And lastly, I'm going to just finish with some blasphemy. I think the risk of starting dialysis with a catheter is vastly overstated.
If you look at old data and patient selection issues, and catheter maintenance issues, I think... It's not such an unreasonable thing to start a patient with a catheter. We do it all the time and they usually live.
And even CMS gives us a 90-day grace period on our QIP penalties, so... If you establish a surgeon and access plan, I think you're good to go. So who monitors access maturation? I don't know, somebody who knows what they're doing.
If you look at all the people involved, I know some of these individuals who are absolute crackerjack experts, and some are clueless. It has nothing to do with their age, their gender, their training, their field. It's just a matter of whether they understand
what makes a good fistula. You don't have to be a genius, you just can't be clueless. This is not a mature usable fistula, I know that when I see it. Thank you.
- Thank you, Larry and Tony, for the invitation. Larry told me I should be provocative so here we go. (chuckles) Those are my disclosures, mostly in the aortic space, although I was a PI for the Humanity Phase II trial. So this is a quote that interventional nephrologists in Arizona told me one day when we were trying
to have a educational, meaningful discussion, so we provide care that is better, faster, and cheaper than what you can provide in the hospital. And we'll address this a little later. What's the roles of the access surgeon, when it comes to advocating or educating
your dialysis patients? Well, when you google advocating for anything, you're going to find mostly political references. And I think there are a number of excellent patient related groups to advocate for policies and principles. But as the surgeon, I think we have
a couple of important roles. One, we need to create the most durable, successful access possible, and as Ted just said, that needs to be individualized for the patient. We need to try and protect and maintain the access and we also have a role in protecting the patient.
We can't underestimate or underemphasize the importance of vessel mapping, both arterial and venous. We frequently get patients referred who have already had their mapping somewhere else but as the surgeon is going to be doing the procedure, we tend to repeat that in the office,
so that we can see it ourselves, because mapping can be variable, can depend on environmental conditions, how cold the patient's room is, their hydration status, so we really try and nail that down. And frequently we find a high bifurcation
of the brachial artery, that's not noted on other mapping. And, again, I think to emphasize what Ted just said, we really need to champion communication between the patient, the nephrologist, and the surgeon, just because you don't receive communication, doesn't mean you can't be the person who provokes
and stimulates communication back to the nephrologist to try and really develop a clear plan. The timing of the hemodialysis is imperative and I think we should consider early cannulation grafts in appropriate patients. What about protecting and maintaining the access,
well these slides were provided to me by Dori Schatell, who's given this talk, you need to arm your patients with information to advocate for themselves and that's really, kind of the theme of what I want to talk about later. Give them pictures of their access,
write them very clear postop instructions, teach patients about cannulation patterns, teach them how to use topical anesthetics for cannulation. Make sure they know what to do in the case of an infiltration or prolonged bleeding, or loss of the thrill.
Make sure they have your contact information, and encourage patients to learn how to self-cannulate. What about protecting the patient? Well, I think it's our, it's the team's obligation but seems to fall on us a lot to educate the patient and their family about their right to choose.
Educate the patient and their family about available providers and facilities in their area. And educate the patient and their family about what services are available at different facilities, and nephrologists , radiologists, surgeons and anesthesiologists.
- Okay, I went to my nephrologist. He told me I needed to get this fistula put in, and then I was directed to the access center, because the way he said it, that's where I had to go to get it done, after I'd already talked to another doctor about doing it,
I was told I had to go to the access center. Okay-- - Oop, let's see. - Um, what she didn't say is that, she didn't like the center in the first place, because originally the doctor that saw her there for the fistula, didn't give us any help.
So he said, I can't do it for you, I don't know what's going to happen, and every time we would ask him, well, is there any solution for her to get a fistula, he wouldn't answer our question and he's like, well, I can't, I can't help you, I'm not going to take it.
So, when they told her told to go to that center, she had told him, can I go somewhere else, somewhere where they're a little bit more professional? And they said, no, you have to go there, they're the specialists. - So, going back to the original comment.
We provide care that is better, faster, and cheaper than what you can provide in the hospital. Well, when you're talking about better, that's really measured only by safety and durability of the interventions, not opinions. And faster, unfortunately, in our area,
some of our access centers are closed on Wednesdays, some of them are closed on Fridays and the weekend. And it's interesting, we often, the surgeons in town often get pummeled on Friday because the access center is closed. And I can tell you that my weekend on call,
I spent about half my day Saturday doing access interventions. And cheaper, cheaper's really only a function of how payers have decided to reimburse. You pay the same amount for staff, electricity, and supplies, whether you're at a hospital,
a surgery center, or an OBL. Unfortunately, some access centers frequently choose therapies that are less effective but cheaper to protect their margins. And perfect examples of these are stent grafts, and drug-coated balloons.
I think hemodialysis patients really want care that is safe, effective and durable. And really, where that's going to be best achieved will depend on what's available in a particular community or region. And most importantly, and I think,
as Ted highlighted, they're really the commitment to providing excellence in access care. And I'll finish with one more little vignette from one of my patients, and these patients, actually this was unsolicited, they just happened to be going off in the office one day
and I had gotten this assignment, I said, you mind if I video this and use it in my presentation? - Basically, in my opinion, what it is, it needs to be patient education. The ones that do talk to me, 'cause I do take control
of my treatments completely. That's why my fistula's in such good shape, 'cause I'll only run 16 gauge needles, which slows down my treatment, which keeps my heart in better shape. That's why I'm still up, walking, doing what I do.
- Thank you very much.
- So first of all I want to tell everybody that you're going to have a hard time finding these tools that I'm going to show you. So before I start the talk I want to tell you how you can find these. Everybody's got phones out there that you can Google on. If you would Google "One minute access check"
it will take you to the website that is the ESRDNCC.org site, and that's where you can find the tools. The other place that these are all located is on the VASA website. If you go to the VASA website, which is
the Vascular Access Society of the Americas, which is VASAMD.org, and you go under "Vascular Access Team", all of these tools are linked. The tools that we're going to talk about were put together by the FistulaFirst and I was on the work group that created these tools,
and they're going to solve the problems that you just heard the rest of the group talk about. It talks about how to collaborate the care, how to assess the maturing and the healing access, and to level the playing field so we're all doing it the same way.
And that's basically what these tools were developed for. That's my conflict of interest. So the patient video that just showed you, the patient said patient education. This is a free, your tax-dollar money paid for this booklet. You can print these for free,
there's no copyright issues on it. This is a patient access planning booklet that explains to the patient all of their choices for renal replacement therapy, what is an access, and what's going to happen to them when they get this access.
This is a fantastic booklet and it also serves as the patient's care plan if you fill this out and use it. It can go between the dialysis facility, the surgeon, and the interventionalist. And I'm sorry it doesn't project well,
but this is just a snippet from the booklet that shows you, for the surgeons in the audience, what's going to happen at your office when the patient comes in. And it gives questions that the patient and the family should ask.
So as surgeons, if you look at this booklet, you use it with your team at your office, you'll be able to be prepared for patients coming in and you can use this tool. This is what I consider the plain ice in the sandbox tool.
This tool was created to define all of the various roles of the dialysis access care team, because we all do different parts of the process, but if we don't work together, it doesn't work. So this booklet explains what everybody's roles are, and again this is a great tool.
If you've got a nephrology practice that you're not happy with how things are coming to you with referrals, or you've an interventionalist that you're having issues with, sit down, have a team meeting, bring all the players together
and use this book to guide it. It really tells you what to do and how to do it. And this is an example of what's going to happen with the care team coming together how you go through the access planning, okay? And this is just some information of what
the surgical appointment should get. When you get the patients to show up and they come to you with no information, you don't really know much about the patient, this booklet helps to prepare the dialysis facilities so they know what to send
and they understand those records should come to you. Now, the main part of these booklets of what we're talking about today is this whole issue of what Ted's slide was about who should assess the access for maturing. Well, this answers that question.
There is a basic tool that will give you a weekly assessment of whether or not that graft or fistula is ready to go. And basically this is the care planning part of it where we make that access plan, we then find the best place to get the access,
we choose, we get the patient to the surgeon so you can place the access, patient goes for the surgery. Then we wait for it to mature, heal, we use the access, we then have to get the catheter out, and then we
have to take care of the lifeline for the rest of the patient's time on dialysis or their transition between different modalities. So, how do we do that? The tools are based, this weekly assessment tools are based on the classic one minute check.
This is actually from Dr. Bether's physical exam that's been taught to nephrologist and dialysis staff for many years. It's a simple look, listen, and feel. There's also an advanced test for the care side. This is for the patient,
and this is for the clinician side. It's the look listen and feel with the arm elevation test, and the augmentation test is also added on at the expert level. Again, all these tools are on the website for you to use. Please use them.
Once you understand the one-minute check, this is then the graft healing slides, and again it's a weekly assessment, and we called it graft healing because grafts don't mature, we just are waiting for the surgery line to heal so that
we can go ahead and cannulate it. If it's an early cannulation graft, this would be adopted for those early cannulation grafts, this is for standard graft material. So we go into week two, this tells the patient, the staff, the nephrologist, everybody on the team
what should we be looking for and what should be happening with that access and when it should be ready to cannulate. By week four, if it's not ready to cannulate, this triggers notifying the surgeon, re-engaging with the team, and figuring out
what's going on with the patient's access, okay? We cannot just let these patients sit there with accesses that are not being used for weeks and weeks and weeks. We have to have a plan. And this is what the tool does. The fistula maturation tool is the same thing.
Again it's weekly assessments, there's week one and two, week three, by week four we're looking for actual signs of change with the fistula. If it's not, we would start to already think of a plan of does this need some assisted maturation.
Week five, we're looking to see is it ready to cannulate. By week seven through ten, it certainly should be ready to go and we should be dealing with catheter freedom. There's also a catheter version, because patients with catheters still need to have their catheters
well maintained so they don't get infection. There's a patient version and a staff version. And again it's the same look listen and feel. We obviously don't listen to a catheter like we do a graft or fistula, but we listen to the patient to make sure they're not having symptoms
of infection or problems with the catheter. And we have to do that because we're all part of this interdisciplinary team. I'm a dialysis nurse, so I'm part of the dialysis team, but we have an interdisciplinary team in the dialysis unit, we have to work with the surgeons,
the interventionalists, whether you're an IN or an IR, we have to work with the patients, we have to bring the family in, it's all about this process of care, and hopefully you'll look at these tools and maybe these tools will help you
with your process of care. Thank you.
- [Audience Member] I created, I wrote, after last year's meeting a great, little card about the step ladder technique, teachin' my patients, I was going to help my patients do it. I'd say about 60% of our patients came back and it wasn't just from Fresenius or DaVita or all the other ones.
They came back and the patients said, "You know doc, the nurses, they tell me, you don't know what you're talking about, that the step ladder technique doesn't need to be used, that I just have to stick the best spot in the access." What do we do?
We've got a really good nephrol- you all are high-level nephrologists, I'm sure your centers aren't like that, but what do we do? We try to teach the patients the right thing to do and they come back, and then the truth of the matter is, you've got a patient who goes to a dialysis center,
gets stuck three times a week with a 14 gauge needle by the same person, they're not going to fight them, they're going to tell them, "Hey, here's how you do it." They become passive, and they sit there and they basically take it.
What do you do? - So that's a great point, and I'm on this campaign against 14 gauge needles, but I found the most effective thing to do to both legitimize your message as well as familiarize the dialysis unit
with your level of expertise is to go to the dialysis unit and do cannulation training, and that's what I do every three months. It's my community service. I carve out a morning, and I go to neighboring community dialysis units
that refer patients to my practice because they get opportunities to ask questions. Once things are explained to the personnel, in most cases, if there's a reasonable explanation behind it, people elect to adopt it.
If you can get the nephrologist who's sending these patients along to be present during these cannulation camps, it can actually be very effective. I would try that. - Go ahead, Surinder.
- Yeah, I mean, from the surgical perspective, I face the same problem all the time. There are many issues which Monique actually talked, in her talk mentioned, that many of these things can be endured rather than cured, like flows, by adjusting the flow
and stuff like that, so one of the things that I've found very useful is that whenever I talk to the patient, these issues come up, I mark them and everything else and tell them how to cannulate. I pick up the phone and ask to talk to the charge nurse
in the dialysis and nicely talk to them about "Hey, I just marked it, take a look at it when he comes tomorrow," and things like that. Communication goes a long way in training the people. I think it's lack of training. Thank you.
- [Dr. Jimenez] I have a comment, Dr. Jimenez from South Florida, and I think that what the panel, I congratulate you, is wonderful, but I think that the companies, DaVita, Fresenius, need to be held accountable.
I think that they hire the cheapest employees that they can get. I think that they have, this is a cattle call. We are trying to do the best fistulas, the best procedures possible, deal with their inadequacies on a one-to-one patient,
but there, otherwise, we're seeing YouTubed videos of their presidents stating the huge profits that they're making. When we call their facilities, I can't even get ahold of the charge nurse. I think we need to hold these companies accountable.
- I think we need to vouch on Oliver's as a guest speaker for next year. For those of you who haven't seen that-- Go ahead, Ted. - That experience is yours, and it's valid in your world, and I understand where that's coming from
although it's not my experience. We're part owners in a couple of FMC dialysis units. We hand-picked our staff. We've got Rose, Liz, Mike sticking our patients. We communicate. We try to do reasonable things.
We don't make a lot of money at it. I got one of the nine station units with hand-picked staff. That's very unusual. I don't think you can generalize. I think it's possible to provide good care in the care model that we have.
It's like anything else, it's education, it's commitment, professionalism, funding it appropriately. There's not a simple answer to your question, I'm sure, but it's not a universal-- - [Dr. Jimenez] I believe the government, or whoever's paying these facilities,
needs to have a system to have more facilities like yours and less facilities that it's a cattle call. - Well that system is coming about in various ways of incentivizing and dis-incentivizing outcomes with financial tools and some degree, that may directly or indirectly achieve some of the goals
that you're espousing because if you put your fistulas, you won't do well on those scores, and you'll get deductions from your payment. - [Audience Member] I'd like to ask a question about the differences between the American Japanese results. I was just wondering if there is any data
as to how heavily calcified the arteries in the forearms in the Japanese population because I feel like some of the fistulas could be perfectly patent and don't show any technical issues that could be corrected, and yet they don't mature or they don't mature enough.
I have a few patients who are heavily calcified and there is no stenosis and the vein looks good, but they cannot achieve flow rates more than 200, and I think that may be the problem. I was wondering one if that's one of the differences why we don't have as many forearm fistulas,
and to follow-up that question, I was just wondering what panel's opinion is to how aggressive we should be. We have heavily calcified forearm vessels without really impediment to flow. The flows are normal despite calcification,
but is this a sign that maybe we should not be doing those patients, even though we can achieve patent fistulas. - I can answer the first question and maybe some of my surgical colleagues can answer the second. To my knowledge, there's no comparative data
that examines the prevalence of calcification in distal arteries in Japan versus the United States. There've been at least five publications that have looked at calcifications and what impact calcification has on the arterial side as well as the venous side.
Michael Elan has actually published on that. Interestingly, it doesn't seem to make a difference, the presence of calcified at the start of dialysis when you're constructing a fistula, doesn't seem to actually impact maturation rates. That said, we have all experienced patients
who have calcified arteries. It obviously limits in-flow and, yet, there's truly no comparative data. My guess is that there is ample calcification in both Japanese as well as American patients and I think that there's, in some cases,
just a different skill set that's involved with the surgeons that operate on these Japanese patients such that they are very successful in getting forearm access. - But Monique, could it be simpler than that? I mean, how about body habitus, you mentioned that,
how about correlating that with BMI? I mean are they a little bit thinner in Japan than the patients we deal with, this is why? - They are, but interestingly, if you look at all the predictors for AV access maturation, body habitus is not a predictor.
Race is, gender is, peripheral arterial disease is, but the presence of obesity is not. The use of transposition and other factors to bring a vessel up to the surface obviously needs to be employed with fatter patients, - That's what I meant.
but body habitus is not a predictor of AV access maturation. - I heard Ted's going to talk later about pump speed. I thought that was one of the big issues comparing dialysis in Japan to dialysis in the United States.
I guess we'll let Ted present that data a little bit later. - Comment? - Surinder. - I was in Japan just last month, and I'm a frequent visitor there. I visit their dialysis units also.
There are a lot of little things that are very different. The whole culture is different. Number one, yes body habitus is there. Patients tend to be generally on the thinner side which makes surgically mobilization much less. - That's the point.
- It's very unusual to see them do a second stage procedure. The reason being most dialysis units have in-house ultra sound. There technicians are called clinical engineers who are basically trained technicians to use ultra sound and cannulate, though the nurses cannulate.
They do have cannula to cannulate as opposed to the hard, solid needles we have, and they really respect their fistula. Anybody misuses the fistula, has an infiltration, there is a consequence for that, and they really revel that fistula.
- Has to be something like that. - Yeah, China's the same. I was in China twice in September. It's very similar, exactly the same set-ups. They use cannulas. They don't use large needles.
Oftentimes they use 17 gauge. They don't go beyond that. Pump speeds are 200. It's just a completely different thought process. People are on dialysis for six hours, and that's well accepted.
- Last question. - [Audience Member] The idea that there's such a traumatic difference between this country and other countries, is there information regarding the use of catheters? It seems to me that most of the patients that I see
have catheters already in place and, as a result, there's not the same enthusiasm for doing anything else on the part of the patient. It's easy. They come in. They don't get stuck,
and the patient doesn't understand the hazard of the catheter as much as we do. I'm wondering if the data that you have about other countries, if there's an overlay to that to the use of catheters? - I think lots of us have opinions about that.
Obviously 82% of dialysis patients in the U.S. initiate dialysis with a catheter and about 60% of those patients still have a catheter in use at 90 days. Interestingly, some of the European countries actually have very similar numbers.
Germany and China, where I was in September, initiates dialysis with the majority of their patients have catheters, but then they actually get them, they get fistulas in them quite quickly. That certainly plays a role in patient's reluctance
to undergo a surgical procedure, but many of the countries that have achieved very high AV access rates actually have high catheter rates at the start of dialysis. - [Audience Member] I also wondered if there's some economic data,
and I noticed that those countries, probably the only ones, in terms of universal healthcare and the availability of healthcare and in terms of what they get when they get it and who has to pay for it,
who's reimbursed by it. - I got a question for Scott and Ted. The issue of predicting when the patient's going to need dialysis, actually, I feel, this is an extremely important issue because once you put that fistula in
the clock starts ticking so if you've put it a year ahead of time, obviously, we're losing year on that fistula. What are the incentives? You mentioned, obviously, patient education, and some nephrologists would like
to put the patient earlier on dialysis. Ted, you mentioned that actually with medical therapy, you could delay that. What are the incentives? Is this something we can alter using certain financial incentives or otherwise?
- I would take issue with the thought that if you create a fistula a year ahead of time that the clock's ticking against that fistula. I don't think that's going to shorten the long-term viability of that fistula to have it in a year earlier. - It all depends on the patient
whether they develop intimal hyper-plasia or not, and this is something definitely we cannot control. - Perhaps. That's a little controversial. As far as the incentives, if you really want to be perverse about it,
a nephrologist in the United States who has an office practice and a dialysis practice, financial interests will be best served by getting the patient on dialysis. They'll make more money. If that's what's driving their decision process,
you will see that happen. I'm sure it does happen because if you follow the money, you'll usually see what's happening. Yes, that is a phenomenon. I don't know how well to re-align incentives to make that less likely,
but it's an important piece of it. I hope it's not too important, but there's definitely some people out there who think that way. - Last comments? - When I finished telling Ted he needs to come to Tucson
to give that talk because we see the same-- I think the problem is there's so much variability within the nephrology community about their approach because we'll see a patient that's hospitalized, we'll get a request for an access, and then the next day a new nephrologist will take over
their services and say, "No, we don't need to start them." So that nephrologist is more likely to try and manage them medically and keep them off dialysis. Unfortunately, I think, like Ted said, follow the money. If you start making reimbursement as we're supposed to be doing based on quality and outcomes
then many of these problems, I think, will go away. I think the challenge is we're much further away from that population health type program than we expected to be at this point. - And in this abomination of a health system that we have, many times patients are started on dialysis
partly because they don't have insurance and when they get dialysis they get insured and so that may be a factor which, for the patient's benefit, gets them out of dialysis and buys them coverage that they don't otherwise have, another insane misalignment of resources.
- Thank you. No relevant disclosures to this presentation. The means to the end is removing Uremic toxins. That's what we want to do. That's what this is all about. We don't really know all the Uremic toxins and how they inter-relate, but there are a bunch
of compounds that have been identified. Urea obviously being one of them, although not necessarily being a particularly toxic compound. It's a small molecular weight marker of Uremia, which is convenient to use
if not clinically meaningful. We've developed, or Frank Gotch and Sargent developed this dimensionless concept of the Kt/V, an index of the body volume water space, which has been cleared fully of Urea and this index has been the standard for comparing dosing of dialysis for about 30 years now.
Since the National Cooperative Dialysis Study in the 80's. And the most recent iteration of this study has been the HEMO study in 2002, I believe this was published. Where they compared a high dose of Kt/V of 1.71 versus standard dose Kt/V of 1.3 and looked at patient outcomes and they were
concluding that the higher dose of dialysis wasn't beneficial. But this 1.3 was certainly better than we were seeing in the old days of 0.9 out of the NKDS studies, so 1.3 or that range has been accepted as the target dose
for dialysis and KDOQI guidelines now suggest that we strive to achieve a single pool Kt/V of 1.4, so we have a little cushion with a minimum delivery of 1.2, and that has been adopted now by CMS and the payers.
That's in our conditions for coverage that we achieve or we strive for a Kt/V 1.2 and now we have this quality incentive program, which might relate a little bit to the question earlier about saving access as we get penalized or incentivized
for doing certain things, and right in our penalty methodology in the top categories Kt/V, if we don't hit that target we get dinged up to 2% of the total payment for dialysis on that.
So it's something that's being identified, monitored, and if you like ... Not negatively incentivized. It's not a reward. It's a penalty for failing to achieve. And also you can go to dialysiscompare.gov now.
You login your unit. Here's my little unit in Hockessin. We got four stars. A nearby unit got three stars. They're really just as good as us, but somebody thinks those stars mean something,
and one of the components in those stars is hitting your Kt/V target, so if I want to get stars and not be seen as a poor performing unit, I need to hit these performance parameters, so that's why the Kt/V is the holy grail for Nephrologist. We need to get that number.
It's a very simple concept. Mathematically, you've got two items in the numerator and one in the denominator, and you want to maximize that parameter. Number one we can dispense with the volume of distribution
of Urea is pretty much determined by the patient. It's total body of water times the fraction. It varies a lot depending on the age, weight, gender, obesity, etc. You can put it in the calculator and same qx metal to deliver that number for you.
But we can't really change that, unless somebody has an amputation, or a large amount of weight loss or gain, then it changes. Time we have complete control over. We can dialyze theoretically as long as we want and in the U.S. we sort of like
to believe four hours has been adopted as a standard. There are some recommendations that wouldn't do that. Patient acceptance of that is variable. I can sit in front of a patient and tell them they need four and half hours, and they may look at me askance,
because they know they don't want it, and if you look at dialysis times in different countries, you can see certain countries like Germany, typically dialyzes closer to three hours. Typical dialysis time in the United States is more like... Did I say three hours?
I meant five hours. And typical dialysis time in the United States is about three and a half hours. There are also resource limitations and cost involved in that. So the third variable is the one we have
the most control over, which is the clearance of Urea. And that's depending on the dialyze of the blood, in the blood, out. the dialyze of that... capacity of that filter to remove the solute of interest, Urea in this case in a dialysate flow,
and there are specs for each kidney. Here is a Optiflux F160 at a blood flow of 300 and a dialysate flow of 500. It predicts we should get a Urea clearance of 271 mL per minute, or conversely a larger kidney, an F180 had a blood flow of 500, a dialysate flow of 800.
We should get a Urea clearance of 412. Obviously, none of these are perfect clearances. The maximum theoretical clearance would be that of the blood speed, but it's impossible to clear it 100% of the blood. So when your asked as a surgeon or a provincialist
to make a functional access what your Nephrologist is really asking for in a customer service world is give me a fistula that flows 150% higher. 150% of my intended pump speed and we're good to go. Need a little cushion on that as well.
And here's how it translates into action. Here's an example on a calculator. Here's a patient, who's a 70 kilogram female, dialysis time three and a half hours, 210 minutes. Her Kt/V calculates at 1.77. All good.
Same parameters three and a half hours, 120 kilogram, 40 year old male. His Kt/V is 0.96, clearly below the target. You're not going to get that guy's clearance with those parameters. If you goose him up to 500 mL per minute
on a minute on a bigger kidney and you achieve a clearance of 410, then the same male with the same treatment parameters will get 1.45, so you've met their target. If you want to do better than targets just put him on four hours and you only get 1.66,
so these are very easily definable, measurable, predictable quantities that you can achieve. And then you've got limiting factors. What is the pump speed? Well, hemolysis through needles is really an overstated concern.
This arterial negative pressure alarm won't let you go below 250 on this machine and if-- 300 is it Debbie? 250, 300 and at that point it will cut off, so you won't be able to drive the negative pressure that high,
and so you've got parameters for each needle, which are fairly fixed, a little latitude in it, but with 17-gauge needle you can go up to 300 and so on. With a 14-gauge needle you can go up to 500 or more, and it's a pretty si le higher flow.
And here's a case where you've got a 2 millimeter radial artery, a small fistula. The access flow measures at 450. You can dialyze at a blood speed of 300 with a 17-gauge needle and you're good to go. Where as you got a huge brachial artery here.
This access flow is greater than 2000. You can run the blood speed at whatever you want. And you can use a needle size of 14-gauge. You can put whatever needle size you want in this fistula. So the point is that one size doesn't fit all. Dialysis dose, and dialysis needles,
and dialysis fistulas need to be scaled to the size of the patient. You got a neonate. You got Shaquille O'Neal. Somewhere in between is our patient. Thank you.
- This is in line with the earlier discussions we have had regarding cannulation and things. I don't have any disclosure with this. Now, Doctor Sher gave me this topic about cannulation mapping, how does it help dialysis staff? I thought I'd probably try to dissect this a little bit by giving a short introduction and try to define
what I'm talking about and try to look into a little bit about who uses this, who cannulates, and what are the critical components required to make the cannulation safe, so on and so forth. And I'll summarize what I am talking about. As we know, for having successful dialysis we need
about 350 to 450 mls of blood going to the machine and this is drawn by putting two needles in a subcutaneous conduit which has got high blood flow, maybe a graft or a fistula. And it requires two needles to get in there, one to pull the blood out to the machine
and second one to push the blood back. So what is cannulation? One can probably say cannulation is the act of insertion of a needle into a vessel to allow blood to be successfully drawn out by the dialyzer pump and returned to the blood vessel.
Who cannulates? Generally if you look in American practice we are talking about technicians cannulating, and technicians, til recently, the basic qualification required to apply for this job was high school diploma. Nowadays some of the units look for MA's and CNA trainings
that that way they have some medical background. But most of the training for cannulation happens on site by senior people who are there and that's the only training people get. Many of the people do not have medical background. So what do they cannulate?
We create all sorts of access. When you talk about fistula we have fistula which are deep, we have fistula which are coiled, we have fistula which are kind of short, we have a fistula long, in the armpit, all over the place. Then we have grafts in our patients.
When they get into problems we try to do all sort of exotic graft like chest wall graft, necklace graft, forearm, upper arm graft, multiple scars. Now obviously, for someone who is got minimum training, doesn't have much medical background, we have to have some sort of a guidance
and that is cannulation mapping. What is cannulation mapping? It is any guidance to facilitate reliable cannulation. And if you think of in terms of guidance we can do it in two ways. One is we can mark and document and communicate.
The other thing is realtime guidance. Realtime guidance can be off site or can be on site. So marking probably should include nature of the conduit. Are you cannulating a graft or a fistula? Those are two different ways of cannulation, 100% different material.
You also need to talk about what are the direction of blood flow. What are the cannulation segments? Where do you cannulate and how deep is the vessel because depth of the vessel determines what angle you use for cannulation,
to be on the safer side. And these instructions should be given to the people who are cannulating. And how do we collect this data? Most of us have access to ultrasound if not we have a lab nearby which has an ultrasound.
Ultrasound can pretty much look into all the parameters including the flow, direction of flow, depth of the vein, size of the vein, cannulation segment, and everything else. We could document it and we could come with form. This is the form I use before sending any
of my patient to dialysis unit before they start cannulating. And this has all the information required for the nurses. We do that. We draw the cannula, we draw the outflow vein pattern, or cannulation segment pattern, and I confirm it
with ultrasound to make sure that if I can draw without using an ultrasound somebody else should be able to find it by clinical exam and I confirm my drawing is right. That way there's no confusion. We draw it on the paper if need be,
send it with the patient. Most of our patients do have cell phones now. We make the patients take the picture with their own cell phone that way they have that documented because this marking is going to go away. And for the marking to stay there for some time
we cover it up with some transparent tegaderm or some sort of a dressing that way when they go to the dialysis they have the marking. They're going with the sheet, with the instruction how to cannulate, where to cannulate, what is the direction of the vein,
how deep it is, maybe you should not use much of an angle, try to keep the needle flat to the skin, so on and so forth. Now, can we do it real time? Real time can be done off site. I have my pediatric nurses who come to my office all the time with the kids
when the first time when I can. I show them with the ultrasound. Any time a cannulator comes to your office and looks with ultrasound, believe me, their whole impression of what is under the skin becomes clearer
because ultrasound shows you what exactly is under the skin there. So, it is a good way of doing it, little bit shy of being real time in the unit. So they can come to you and when they see such things, you try to have results like this.
Here's a button hole which is created not on top of the vein because it's very superficial and you may cannulate, you may infiltrate, but it's created on the side of the vein. And that is only because they had a mental conception of how to do this button hole, or train the button hole,
and it's working pretty well for a long period of time. Now, real time cannulation can be done in the units. There are lot of articles out there giving you how to do it, how to image a vessel, and how to put the needle in. And some people have started writing about it
because many of the units have acquired ultrasounds. Obviously it's kind of based on who's running the unit. And this is not a routine or a norm because most of the companies they don't have funding to get the unit. But you know I was talking to you about being in Japan. When you go to their unit they do have
hand held ultrasound machines and they do categorize their patients as patients who are easy to cannulate, patients who are in between, and patients who are difficult to cannulate. Patients who are difficult to cannulate do use ultrasound for cannulation.
They hardly ever superficialize their vessels. So there are real advantages for using an ultrasound real time. Now, obviously the disadvantage becomes costs associated with it, but I feel a cost saving done by ultrasound by preventing infiltrations,
infiltration related hospitalization, loss of access, need for catheters, so on and so forth by far supersedes the cost in ward in getting one or using one. So just to summarize. Morphology of the access can be very varied.
Existing training pathways for cannulation personnel is inadequate to produce expert cannulators. Any cannulation mapping is valuable to increase cannulation safety and the patient's comfort. Ultrasound is an excellent tool for cannulation mapping. Real time ultrasound is useful
to provide cannulation guidelines and availability of real time ultrasound in dialysis unit is cost saving measure that could significantly impact patient safety and satisfaction. Thank you.
- [SPEAKER] I have a disclosure, this talk is about a cannulation simulator that I've been working on for about 3 years. It's finally come to the point where we have established a company that, to further develop it and TMC is the initials of my son, whose a lawyer. I told him if you set up this company for free,
I will put your name on as the, the company. I also want to acknowledge Debbie and Janet for this. You know, as a surgeon it would be full hearty for me to sit down and invent a simulator. You need users of the device for all the in-put, so I kept going back to them, going back to the
dialysis nurses in my community, to get their input and so this is what we've come up with. I really don't need to talk about the importance or the consequences of mystics and there's a lot of literature
on that area, but what is interesting is for a surgeon to go into the nursing literature and learn about the psychological impact on patient's from mystics but also the psychological impact on the nurses and the techs. It is, it is really
it is devastating to the nurses and there are nurses that over time become less confident of their cannulation skills. There's this notion of perpetual novice, there's a lot of discussion about the culture in dialysis units that I was unfamiliar with as a surgeon and all
of these papers talk about the need for on-going education and practice. Their cannulation camps, these are expensive and they provide very little training, the simulators are un-realistic, they have high-maintenance, they don't really provide a thrill or a pulse and so most of
these nurses actually can't practice on patients. So, before we started developing this, we had a hypothesis that the perpetual novice is unable to visualize the fistula based on palpation alone and that is the fundamental problem. They have to be able to see a fistula
like this to reliably cannulate a fistula. So we went to Debbie, we went to Janet and asked, OK what is the characteristics of the ideal cannulation simulator? Would need teach the 4 core cannulation steps, we need to be affordable, low-maintenance, preferably fluid-less,
as the nurses it would be able to test those folks that are just beginning cannulation as well as more advanced nurses. It would have an alarm to prevent back-wall sticks, it would train nurses in the identification of a stenosis within in fistula. It would create a
realistic thrill and there would be no based on our initial hypothesis, this was ours. We did not want to provide any visual clues as to the location of the fistula or the depth. It would require only palpation to stick it. And this is what we came up with,
there's no up, there's no down, there's no In this, under our simulator, there are a number of fistula elements and we can turn on these individually and they are tasked to identify the fistula elements that is actually live. The skin on top of the fistulas
is silicon, it's resistant to stick, it's hard to see this cannulation needle punctures, however if those needle punctures, when they develop you can lift tops, spin it and those punctures are no longer correlated to the location of the fistulas underneath.
This is the control panel. You can control the level of the thrill, you can have different levels of the skin to make it more challenging to stick these. The wings of this needle
has been removed but the cannulator uses a standard dialysis needle for the device. When you hit the fistula it creates a light which simulates the return of blood.
So in looking at what we were able to capture all of these elements of the ideal simulator, it's affordable, it's a plug-in play where if an element breaks you can, it's modular, you can disconnect it and plug-in another one. No fluids,
it has just like the old operation games, you touch the back-wall, it alarms. We have one element that's not meant to be stuck but it creates a pulse on one side, a weak thrill on the other side to train that stenosis. We have curved fistulas.
The thrill is quite simple, we generate the thrill through the use of a cellphone motors that create the vibration. Those can be bought for less than $1 on Amazon and it provides no visual clues to the location. We've completed the development of the
device that now needs manufacture specifications, we have a manufacture initial testing has been completed by a large dialysis company and we're working through our first purchase order. We are developing a prototype that's much cheaper, must simpler sleeve that will go over a
patient's arm that overlies their existing fistula and they can self-train on cannulation and I'm working with a Ph.D. who started this project, he's applied complex sensors to the cannulation device that you saw earlier and he's received a K-1 award to study the
mechanics of cannulation and Prabir Roy-Chaudhury is his mentor for that project. Thank you.
- So this was born out of the idea that there were some patients who come to us with a positive physical exam or problems on dialysis, bleeding after dialysis, high pressures, low flows, that still have normal fistulograms. And as our nephrology colleagues teach us, each time you give a patient some contrast,
you lose some renal function that they maintain, even those patients who are on dialysis have some renal function. And constantly giving them contrasts is generally not a good thing. So we all know that intimal hyperplasia
is the Achilles Heel of dialysis access. We try to do surveillance. Debbie talked about the one minute check and how effective dialysis is. Has good sensitivity on good specificity, but poor sensitivity in determining
dialysis access problems. There are other measured parameters that we can use which have good specificity and a little better sensitivity. But what about ultrasound? What about using ultrasound as a surveillance tool and how do you use it?
Well the DOQI guidelines, the first ones, not the ones that are coming out, I guess, talked about different ways to assess dialysis access. And one of the ways, obviously, was using duplex ultrasound. Access flows that are less than 600
or if they're high flows with greater than 20% decrease, those are things that should stimulate a further look for clinical stenosis. Even the IACAVAL recommendations do, indeed, talk about volume flow and looking at volume flow. So is it volume flow?
Or is it velocity that we want to look at? And in our hands, it's been a very, very challenging subject and those of you who are involved with Vasculef probably have the same thing. Medicare has determined that dialysis shouldn't, dialysis access should not be surveilled with ultrasound.
It's not medically necessary unless you have a specific reason for looking at the dialysis access, you can't simply surveil as much as you do a bypass graft despite the work that's been done with bypass graft showing how intervening on a failing graft
is better than a failed graft. There was a good meta-analysis done a few years ago looking at all these different studies that have come out, looking at velocity versus volume. And in that study, their conclusion, unfortunately, is that it's really difficult to tell you
what you should use as volume versus velocity. The problem with it is this. And it becomes, and I'll show you towards the end, is a simple math problem that calculating volume flows is simply a product of area and velocity. In terms of area, you have to measure the luminal diameter,
and then you take the luminal diameter, and you calculate the area. Well area, we all remember, is pi r squared. So you now divide the diameter in half and then you square it. So I don't know about you,
but whenever I measure something on the ultrasound machine, you know, I could be off by half a millimeter, or even a millimeter. Well when you're talking about a four, five millimeter vessel, that's 10, 20% difference.
Now you square that and you've got a big difference. So it's important to use the longitudinal view when you're measuring diameter. Always measure it if you can. It peaks distally, and obviously try to measure it in an non-aneurysmal area.
Well, you know, I'm sure your patients are the same as mine. This is what some of our patients look like. Not many, but this is kind of an exaggerated point to make the point. There's tortuosity, there's aneurysms,
and the vein diameter varies along the length of the access that presents challenges. Well what about velocity? Well, I think most of us realize that a velocity between 100 to 300 is probably normal. A velocity that's over 500, in this case is about 600,
is probably abnormal, and probably represents a stenosis, right? Well, wait a minute, not necessarily. You have to look at the fluid dynamic model of this, and look at what we're actually looking at. This flow is very different.
This is not like any, not like a bypass graft. You've got flow taking a 180 degree turn at the anastomosis. Isn't that going to give you increased turbulence? Isn't that going to change your velocity? Some of the flow dynamic principles that are important
to understand when looking at this is that the difference between plug and laminar flow. Plug flow is where every bit is moving at the same velocity, the same point from top to bottom. But we know that's not true. We know that within vessels, for the most part,
we have laminar flow. So flow along the walls tends to be a little bit less than flow in the middle. That presents a problem for us. And then when you get into the aneurysmal section, and you've got turbulent flow,
then all bets are off there. So it's important, when you take your sample volume, you take it across the whole vessel. And then you get into something called the Time-Averaged mean velocity which is a term that's used in the ultrasound literature.
But it basically talks about making sure that your sample volume is as wide as it can be. You have to make sure that your angle is as normal in 60 degrees because once you get above 60 degrees, you start to throw it off.
So again, you've now got angulation of the anastomosis and then the compliance of a vein and a graft differs from the artery. So we use the two, we multiply it, and we come up with the volume flow. Well, people have said you should use a straight segment
of the graft to measure that. Five centimeters away from the anastomosis, or any major branches. Some people have actually suggested just using a brachial artery to assess that. Well the problems in dialysis access
is there are branches and bifurcations, pseudoaneurysms, occlusions, et cetera. I don't know about you, but if I have a AV graft, I can measure the volume flow at different points in the graft to get different numbers. How is that possible?
Absolutely not possible. You've got a tube with no branches that should be the same at the beginning and the end of the graft. But again, it becomes a simple math problem. The area that you're calculating is half the diameter squared.
So there's definitely measurement area with the electronic calipers. The velocity, you've got sampling error, you've got the anatomy, which distorts velocity, and then you've got the angle with which it is taken. So when you start multiplying all this,
you've got a big reason for variations in flow. We looked at 82 patients in our study. We double blinded it. We used a fistulagram as the gold standard. The duplex flow was calculated at three different spots. Duplex velocity at five different spots.
And then the diameters and aneurysmal areas were noted. This is the data. And basically, what it showed, was something totally non-significant. We really couldn't say anything about it. It was a trend toward lower flows,
how the gradients (mumbles) anastomosis, but nothing we could say. So as you all know, you can't really prove the null hypothesis. I'm not here to tell you to use one or use the other, I don't think that volume flow is something that
we can use as a predictor of success or failure, really. So in conclusion, what we found, is that Debbie Brow is right. Clinical examinations probably still the best technique. Look for abnormalities on dialysis. What's the use of duplex ultrasound in dialysis or patients?
And I think we're going to hear that in the next speaker. But probably good for vein mapping. Definitely good for vein mapping, arterial inflow, and maybe predicting maturation. Thank you very much.
- [Man] A question for Dr. Sails. When we tried looking at volume flow with prediction of fistulas, I'm wondering if some of your data may be affected by where the lesions are in as much that the collateralization on the shoulder may be able to maintain the volume flow, but yet, with fistula, that's not functional.
- Yeah, that's a great point. We looked at that. We did a multivariate analysis of all the different spots that we had, and we really could not correlate anything very well with proximal inflow lesion, outflow lesion, central lesion, in graft or in fistula stenosis.
It just, I just think that the technology is not there yet. I think that we're too dependent still on human error, human calculations, and I think that, I think when we talk about, we were talking the other day at the Vieth about artificial intelligence.
I think this is a perfect example, the way you should be able to create the technology to measure the diameter very accurately and measure the flow and come up with a number, but we don't, at least in our hands, we can't do that yet. - Okay, Dr. Chenoi?
- I've been a big proponent of measuring flows, but again, I fully understand what you say. I don't think flows are going to be predictors, but where flows can be used, number one, they can be reproducibly, accurately measured if we measure it in the brachial artery
for the reasons you gave. That is because your arterial diameter is stable, you don't have multiple changes, you don't have acute flow changes, so velocities will be the same, and measuring the diameter becomes much simpler, and many of the machines allow you
to do a direct measurement rather than measuring it and plugging it in. You can do a longitudinal access and measure it directly, so that is a very predictable and reproducible way of major flow. Obviously, saying direct flow measurement,
not a direct flow measurement, and you already very well stated why vein flow measurement did not correlate because the same vein, if you measure in three places, you will get three different flows. We had that thing.
So I've been using artery. How I use the flow is more for surveilling different accesses because if they come with a problem, you know what it was before, what it is now. If you are following a patient, you can very well use the flows and determine
whether they need intervention or not. A lot of time, just a flow tells you that this fistula might give a venous alarm, but if your flow is around 800 mils, all you need to do is understand that you got outflow vein stenosis, and carefully monitor the venous alarm
and reduce your dialysis pump speed to a little bit so that you (mumbles). So there are a lot of ways we can use it, but as far as prediction of maturation, probably flow is not a good way to predict. - [Man] We've got a question for Dr. Ross.
Could you elaborate a little bit more on the concept of first, you figure out the inflow and then outflow, and then you choose the conduit. Isn't that probably more accurate in patients who have complex access? In patients who do not, don't you want to maximize
using a vein so you find where is the most distal good vein you could use and then choose the inflow for it? - [Man] Yeah, we want to choose the inflow. First of all, by choosing the appropriate inflow, you want to do two things. You want to have enough flow for the access,
but also you need enough flow going down to the extremity. It does not mitigate trying to do fistulas as much as we possibly can, but we don't want to do what I think is called fistula crazy, where we're trying to establish the conduit with jeopardizing the inflow for the conduit
and of the outflow, but the principle is starting distally with a fistula and just working more approximately. That is still there. We just have to be wise about doing that. - Okay, you just wanted to be sure. - Yeah.
- Hey, go ahead, Dave. - I just wanted to make one, push back on one comment in your talk, John, that you showed a case where a guy had a contraindication to a thigh graph because of peripheral arterial disease. I'd like to push back a little bit on that
for a couple of reasons. First of all, in ours, we did a series of about 130 thigh grafts, found that the limb amputation rate was high, and I think a lot of this limb amputation rate that's attributed to vascular access procedures
is actually due to the underlying, underlying peripheral arterial disease, not due to steal. A lot of that the, on large vessels proximally, there is adequate flow. We see it all the time with the proximalization of the arterial inflow, going, is a very good operation
and is fairly resistant to steal, even if somebody has pretty significant forearm arterial disease and so before people get in their mind that there's contraindication to peripheral arterial, that a thigh graft is contraindicated to peripheral arterial disease,
I'd like to kind of tone down that thought. I've done this, dozens of those, and it's not as common as one might think. - I think it depends on how technically you do this. Typically, what I like to do is a lateral femoral thigh graft, starting low on SFA
and working my way up. I've seen some issues. I've done several hundred of these. I'm very old. Particularly, if I have to come off the common femoral, if I come off the common femoral, I want to know
what's going on with the profunda, and David, when I see significant profunda disease, and it would, by the way, all these patients would get an aortagram and run off, I'm just seeing a few issues there, but I agree with you is that most of the time, when you go to a thigh graph, these are older folks.
They've lost the central system, and they are going to have, most of them, you're going to be sewing through calcium. - That is, the question was going to ask. What's the algorithm that everybody uses for fistula maturation? So if you get a duplex six weeks out,
and the patient's on dialysis, fistula's not mature, we're recommending an intervention. A lot of patients who are not on dialysis and they have either poor or marginal volume flows, and I wonder whether you mature this (mumbles) some guidance, give them contrast,
wait until they're ready for dialysis. Is there a critical level below which you're worried the fistula will fail you need to do something right away? Anybody have any thoughts on that? (man mumbling)
- Go ahead. - I evaluate every single patient of mine very religiously. If they don't come, they get a phone call to come back, or they never, I'll just get a phone call that your patient did not show up, so I have a lot of experience with this.
Every fistula, I mean I see them 10 to 14 days, within that time point, and I see them a month later. - What do you do with that month period when it's supposed to be mature? - So this what I was going. When you see them, every fistula that fails
or fails to mature has a underlying reason why it is not maturing. - Okay, I agree. - It may it be when the flow is low, it is usually the inflow issue somewhere in and around anastomosis.
You free the pulsatile flow. It is somewhere in the conduit or peripheral outflow or central outflow, so generally, if I identify a problem, even if at the first visit, I follow it up with a dedicated ultrasound just to look at it, if I find a problem which is hindering maturation,
I am a believer in early intervention, not wait on it because if it is not done that time, it's not progressing. If there the equivocal situation where you think that it is there, it is maturing but it's not there yet, I will follow them more closely to see whether there is a progression of maturation
or regression of maturation. - If there's a critical level below which you worry the fistula will fail, are you worried about giving contrast to these patients with ultrasound guidance for secondary interventions? How do manage that?
- I'm not hesitant to give small amount of contrast. There are enough studies there showing that small amount of using small amount of contrast to do targeted intervention should not hurt the kidney function or anything. Now, we do use sometimes, intraoperatively,
ultrasound-guided interventions. If it is to be done on the table instead of calling for C-Arm and stuff like that, I just do the ultrasound guidance to do a intervention. - Sharik, got a question for you about the sirolimus patch.
Since you and I discussed it now few years back, I've been fascinated by it. Could you elaborate a little bit on where are you with this concept and whether you think it's coming down the pipe for us to actually use it? - So right now, we are in the closing stages
of a phase three clinical trial in the United States, and once the randomization is completed, then the primary endpoint will be six months after the last patient has been enrolled, and the primary endpoint is the proportion of fistulae that are suitable for dialysis at six months.
- So you expect that that's going to decrease intimal hyperplasia because I know you place it around the distal anastomosis rather than maturity or you're linking the two together. - So yes, so the primary action that we want to harness from the sirolimus molecule is its demonstrated benefit
on suppression of new intimal hyperplasia by interrupting the cell cycle between G1 and the S phases. That's very well known. There could be other benefits as well, including some anti-inflammatory effects of sirolimus, which could be equally important in the early days
after fistula surgery, but the combination, the expectation is that by keeping that juxta-anastomotic region patent enough to improve the flow, that should hasten and ultimately improve maturation. Thank you.
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