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The basic concept of hemodialysis access is to make a route to the central circulation in CRF patients. Vascular access procedures and subsequent complications represent a major cause of morbidity, hospitalization and cost for hemodialysis patients. Native arteriovenous fistulas (AVFs) are preferable to synthetic arteriovenous grafts because they are associated with a lower frequency of thrombosis and infection, as well as greater longevity. AVFs that are never usable and early graft failures are associated with the common problem of inadequate vessel (artery or vein) selection. The surgeon’s preoperative physical examination is the primary basis for AVF versus graft selection. Only palpable veins are considered for construction of AVFs, and the more proximal draining venous anatomy is not known prior to the operation. Physical examination is the traditional surgical evaluation performed prior to hemodialysis access placement. Palpation and inspection are difficult in obese arms, and few patients have vessels that are visible throughout their entire course. Patients with end-stage renal disease have often had multiple venipunctures and numerous intravenous lines placed and thus have an increased likelihood of venous stenosis or occlusion. Central vein problems are difficult to detect at visual inspection. By colour Doppler analysis vessels can be assessed for size, stenosis, and occlusion. US mapping assists in surgical planning and is especially valuable in patients who are difficult surgical cases (eg, obesity, diabetes, history of prior access, elderly women).
This lecture contains two separate sections: 1-Vascular mapping prior to access placement and 2-Fistula maturity by US evaluation. Ultrasonography (US) is an excellent modality for hemodialysis access evaluation because it is readily available, non-invasive and inexpensive. It avoids the risks associated with iodinated contrast material and ionizing radiation.