Factors that may be helpful in preparing the patient for placement of a permanent HD access include the following:
1.1 The veins of the dorsum of the hand should be the preferred site for IV cannulation.
1.2 Sites for venipuncture should be rotated if arm veins need to be used.
1.3 Patients with CKD stage 5 should be educated on the risks and benefits associated with catheters and strongly encouraged to allow the evaluation for and creation of a fistula for long-term access when appropriate. Such discussions with the patient should be initiated months before the anticipated start of dialysis therapy.
1.4 Alternative imaging studies for central veins include DDU and magnetic resonance imaging/MRA.
Ideally, patients should have a functioning permanent access at the time of dialysis therapy initiation. Function implies that the access not only deliver adequate blood flow for dialysis, but also may be cannulated easily and repetitively. Timely attempts to create a primary fistula before the anticipated need for dialysis therapy will allow adequate time for the fistula to mature and sufficient time to perform another vascular access procedure if the first attempt fails, thus avoiding the need for temporary access. Early referral of a patient with CKD to a nephrologist is needed to facilitate CKD therapy with medications and diets that preserve kidney function. In addition, counseling patients on CKD treatment options is essential to plan for ideal access (ie, PD and HD access).
Duplex ultrasound is the preferred method for preoperative vascular mapping. Vascular mapping in preparation for the creation of a vascular access refers to the evaluation of vessels, both arterial and venous, of patients with CKD who selected HD in preparation for the creation of a vascular access. Vascular mapping should be performed in all patients before placement of an access. Preoperative vascular mapping was shown to substantially increase the total proportion of patients dialyzing with fistulae.36-39 Several studies support the 2.0- to 2.5-mm vein diameter threshold for successful creation of a fistula.36-39 Radiocephalic fistulae constructed in veins with a less than 2.0-mm diameter had only 16% primary patency at 3 months compared with 76% for those with veins greater than 2.0 mm.36 In a pivotal study,39 a threshold of 2.5-mm vein diameter assessed by using duplex ultrasound was used; this resulted in an increase in fistula creation of 63% compared with a retrospective 14% rate in the absence of vascular mapping.22 A similar study using the same duplex ultrasound criteria showed a fistula increase from 34% in historical controls to 64%. Importantly, in this study, duplex ultrasound altered the surgical plan based entirely on the surgeon's clinical evaluation, resulting in increased placement of fistulae.72
Although angiography remains the standard for evaluating the central veins, the central veins may be assessed indirectly by using duplex ultrasound.44 Compared with invasive venography, duplex ultrasound had a specificity of 97% and sensitivity of 81% for detecting central vein occlusion.45 Alternatively, MRA may be used to evaluate central veins.46