section five chapter 30 dialysis graphs and fistula so we're going to uh talk about the difference between an AV fistula and graft identify duplex findings of a normal AV fistula normal Venus and arterial anatomy in the upper extremity Venus Doppler findings in an uded axillary vein and proper Pro positioning for Imaging a radio spalc fistula and quantify the degree of stenosis based on doler findings so a little bit of background the incidence of chronic kidney disease and endstage renal disease is increasing in the United States um the goal of arterial venous access is to provide long-term hemo dialysis access with a low frequency of reintervention and low complication rate the goal is to create an autogenous fistula as far distantly as possible in the non-dominant arm preserves proximal vessels for potential future access and then it allows the patient to carry out normal daily activities so autogenous access preferred for Superior patency rates and low complications upper extremities are preferred lower infection ction rate and easier access reinvention is required with failure of a fistula to mature in thrombos autogenous fistulas have better long-term patency uh patency rates than sthetic graphs however they have a lower maturation rate and higher early thrombosis rate pre operative evaluation is important for um the successful creation of long-term axis and maturation a vein mapping is performed to determine suitability of veins for placement of the ficial they have to be a certain size duplex assessment can be performed um before the patient begins dialysis or also in patients who have um undergone other access procedures so here are the vessels in the arm so normally with the they'll do is they'll connect the radial artery to the C to the calic vein so got to document the patient history their current medical history trauma history medications that they have previous um access procedures which arm is dominant so if they're right-handed they're going to want to use their left arm um to create this fistula and then any any type of Contra indications with the patient maybe they have a central Venus catheter already in place pacemaker def defibrillator or they've had a mastectomy so assessing the patient now they're going to want to look at the uh blood pressures in both arms and um also if the pulses are present with the brachial radial and oler arteries and then an allen test to demonstrate if there's the um Palmer Arch is intact because if they um use that radial artery uh and connected to the calic vein and they don't have a pton Palmer Arch then they're going to lose um circulation to their hand assessment of superficial Venus system using tourniquets so there's the arteries um of the upper arm of the arm of course you're going to want to explain your pro the procedure to the patient and have a warm warm room so that the vessels don't vasoconstrict or have a vasos spasm um the patient can be sitting or be lying down and then the arm needs to be um preferably just at their side or even laying in your La if it's the right arm that you're going to be um scanning we're going to want to use a high frequency transducer we're going to look at the deep and superficial Venus system color spectral doer also used arterial system evaluated first if the arterial system is okay diameter is greater than 2 mm with no uh significant abnormalities then we're going to proceed to evaluating the Venus system um non-dominant arm evaluated first then the dominant arm if that non-dominant arm is not up to par so assessment of the arterial system uh includes direct Imaging indirect physiologic tests um can also be used uh depending upon the patient situation grayscale Imaging um is used to to assess diameters of the owner and Radial arteries they have to be um a suitable diameter um to that they can be used successfully measurements made at the at least at proximal and distal segments also sets for calcification Cal thickness stenosis and compliance compliance would be where we have cooptation that there's no thrombosis um we can have calcifications in veins as well and you can have blood clots in arteries um here is a calcified brachial artery so assessment of the Venus system we're going to be looking at the superficial veins the calic and basilic uh and at times the median cubital vein walls should be compressible free of thrombus webbing um and any kind of um calcifications um you're going to record the vein diameters and document patency depth wall thickness whether or not there's calcifications or thrombus and then when um when you're assessing the Venus system you um are going to be using a tourniquet on the arm to ensure um vein dilation here's the basilic vein on a patient very superficial here um and they they're measuring the diameter in here's uh a vein with thrombus so here's subclavian showing respiratory phasicity uh preliminary results should be recorded uh and Contra indications include um IV lines open wounds dressing and then limited patient positioning arteries and veins should be chosen for the best chance of ensuring a mature AV fistula so maturity is defined as dilated easily palpable and usable fistula with a flow rate of greater than 350 ml a minute radial oler and brachial arterial diameter should be greater than 2 millimeters um the book has changed a little bit from this addition um 2 to 2 and 1 12 mm so the vessel walls should be smooth and free of disease calcifications are going to be bright um and then we'll also shadow on the Venus system vein diameter should be greater than 200 2.5 mm walls should compress completely ensuring there's no thrombus if there's a thrombus in there then that vessel is not going to be able to be used for the fist so um different types of access is possible the most common is called a br breasia Camino fistula the calic vein is connected to the distal radial artery at the wrist so there's other types of fistula posterior branch of the radial artery to the calic vein um using the basilic vein instead of the spalc and basilic vein has to be transposed and juxtaposed to connect to the distal artery inject toose simply means to place or deal with close uh together for contrasting effect so near nearby here uh is is a radio falic Fishel so they're connecting the calic vein here to the radio artery they can also use the B basilic vein but they have to um move it if upper extremity vessels are unsuitable then they can also look at the lower extremity vessels that's not very common common uh femoral or superficial femoral arteries are connected to the sainis or uh common femoral veins here's a brachio falic fistula here's where they're using the basilic and they have to move move it over so for the fistula to be mat mature that's where it's going to be able to be used it takes um up to 3 months 8 to 12 weeks use of small or suboptimal veins is associated with low maturation rates and it might require a second intervention so they have to follow up on these patients outflow vein segment fistula an asmosis and Vin to graft an asmosis they're prone to stenosis so here's a forarm loop a Graft in the upper arm so some other indications for followup and the patient and develops the pseudo aneurysm if they get a stenosis in their graft if they get a hematoma arterial stenosis Perry fistula Mass decrease thrill so when they connect that artery to a vein that that blood on the arterial side is moving very very very fast onto into the the Venus side so that vein is going to distend due to the increased flow and the ve Venus side is very low pressure and then the arterial side is very high pressure so you'll have this you'll feel it it's called you know it's a thrill um pulsatile flow difficult canulation um elevated recirculation time elevated Venus pressure low UA reduction rate excessive bleeding following dialysis arm edema or infection or arterial steel syndrome so here is um some Imaging um of an A V graft with with the Venus anastomotic stenosis indicated at that white area are Arrow here and here is after intervention and we got it going again here is a patient that has a pseudo aneurism so that's a hole in the vessel wall and I'm sure they could palpate that look how superficial it is here's a pseudo aneurysm and someone's fistula and there's the yin-yang very superficial so they're scanning right on top of it physical exam excess for the presence and quality of the thrill um visually inspect the arm and the access site see if it's got some redness or swelling if there's collateral vein um don't press very hard and use a high frequency transducer and set your Doppler to high flow settings uh gray scale we're going to look for um any kind of masses Around The graft cud aneurysm stonic valves animal flaps of course you're going to want to measure the the diameter of the fistula different parts of it proximal to the anastomosis at the anastomosis distal to the anastomosis transverse um scanning going be able to look for some side branches um use Doppler to identify or to evaluate the patency of the fistula identify any areas of stenosis so you're going to be using your color and have it set appropriately measure velocities proximal to within and distal to um the stenosis if you find any arterial inflow is assessed and we record psvs within the native artery also um um record Peak systolic velocities at the anastomosis through the body of the fistula and the Venus outflow got to get them all volume flow measurements useful when evaluating ACC um evaluating access function um use a large sample volume you can adjust it use small or large but this is saying used large measurements made midf um at a normal flow site calculated as flow is equal the time average velocity multiplied by the area by 60 here they're measuring um flow volume uh arterial steel syndrome check for Retrograde flow in the distal native artery compressed graph then release uh then reassess flow Direction absolute for impress should be obtained with and without graph compression and I'm going to pause so we can finish up on the next screencast