Review for Hemodialysis Technician Access to the Bloodstream Questions and Answers

What remains one of the major problems in the chronically dialyzed patient? - maintaining patent access with adequate blood flow. What is the order of preference for a vascular access for patients undergoing chronic hemodialysis? - - wrist (radial-cephalic) - elbow (brachiocephalic) - transposed brachiobasilic vein - cuffed tunneled CVC The 2002 NKD K/DOQI Clinical Practice Guidelines for CKD recommended initiation of a vascular access when the GFR is what? - less than 30 mL/min/1.73m2 What is an arteriovenous fistula? - An internal access surgically created by a vascular surgeon using the patients own blood vessels. Vein && Artery connection What causes the vein to become enlarged, distended, and prominent, allowing placement of large-gauge needles for the dialysis treatment? - The diversion of arterial blood into the vein What are commonly used for an AV fistula? - - radial artery and cephalic vein (lower arm) - brachial artery and cephalic vein (upper arm) What allows for identification of appropriate veins and helps to rule out sites taht are not suitable for use? - venography What is a majore cause of early AVF fistula failure? - selection of suboptimal vessels Which arm is preferred when a patient needs an access placed and why? - nondominant bc it helps the patient maintain their present standard of living and and also to facilitate self-cannulation if they perform their own dialysis care. How long may the AVF take to mature enough for cannulation? - up to 4 months or longer What is Basilic Vein Transposition? - New technique used to create a vasular access in patients with inadequate vessels in the wrist. This transposed vessel technique involves dissecting the basilic vein and transposing it anteriorly and subcutaneously while anastomosing it to the brachial artery. This transposed vessel provides a large surface area for cannulation and requires only one anastomosis. The incision for this access is rather larger witht he start of the incision being at the midantecubital fossa and extending to the medial aspect of the arm of the axilla. What is the main advantage for the Basilic Vein Transposition placement? - Avoidance of using a synthetic graft What is an AV graft? - Biologic or synthetic matierial that bridges an artery on one end and a vein on the other end. A vascular graft is subsituted when? - when a patient is not a candidate for a native AVF What type of material is utilized most frequently for grafts? - synthetic What configurations may a graft be placed? - - straight - looped - curved What is the earliest a AV graft may be used after placement? - 2 to 6 weeks, with surgeons approval Why do you need to know the direction of blood flow in the AV graft? - In order to properly place the needles for the hemodialysis treatmetn. How should the venous needle always be placed? - In the direction of the blood flow (artery to vein) How do you determine the flow of blood in a looped configuration AV graft? - After gently depressing the graft at midpoint, you can listen for a bruit or feel for a thrill on each side of the graft. Because you have occluded the flow of blood at midpoint, you will be able to fill a thrill or hear a bruit on the side where the blood is entering the access (arterial side). The side of the graft with little or no thrill or bruit would be the venous side. What is another technique used to determine the flow of blood in a AV graft? - palpate the graft at midpoint once the needles are placed. the arterial needle will continure to have a flashback of blood when the graft is compressed. What types of grafts are available? - - synthetic grafts (Dacron, PTFE) A newer form of PTFE allows for needle insertion immedialtely after placement, although the manufacturer recommends waiting how long? - 5-7 days What are the advantages of AV graft? - - can be used sooner than AVF, usually after 2 weeks - maturation time fro the vessel to enlarge is not required - larger vessel size allows fro easier cannulation - large surface area for cannulation - ability to span to larger areas of the body - variety of shapes and configurations - ease of surgical implantation What are the advantages of AV fistula? - - excellent patency rate - can last for decades - highest BFR - Lowest rate of complications (infection, steal syndrome, stenosis) - Improved performance over time as access developes - Development of collateral circulatin, which creates addition branches for cannulation What are the disadvantages of AV graft? - - higher infection rates - may reject graft material - higher rates of thrombosis - stenosis at venous anastomosis from initial hyperplasia - no development of collateral circulation What are the disadvantages of AV fistula? - - Failure of vein to enlarge - more difficult to cannulate than graft - comsmetically unattractive