Surveillance of hemodialysis vascular access

Abstract

A mature, functional arteriovenous (AV) access is the lifeline for a hemodialysis (HD) patient as it provides sufficient enough blood flow for adequate dialysis. As the chronic kidney disease (CKD) and end-stage renal disease (ESRD) population is expanding, and because of the well-recognized hazardous complications of dialysis catheters, the projected placement and use of AV accesses for HD is on the rise. Although a superior access than catheters, AV accesses are not without complications. The primary complication that causes AV accesses to fail is stenosis with subsequent thrombosis. Surveying for stenosis can be performed in a variety of ways. Clinical monitoring, measuring flow, determining pressure, and measuring recirculation are all methods that show promise. In addition, stenosis can be directly visualized, through noninvasive techniques such as color duplex imaging, or through minimally invasive venography. Each method of screening has its advantages and disadvantages, and several studies exist which attempt to answer the question of which test is the most useful. Ultimately, to maintain the functionality of the access for the HD patient, a team approach becomes imperative. The collaboration and cooperation of the patient, nephrologist, dialysis nurse and technician, vascular access coordinator, interventionalist, and vascular surgeon is necessary to preserve this lifeline.

Keywords: Hemodialysis; arteriovenous fistula; arteriovenous graft; surveillance; vascular access.

Figure 1

Graphic representation of the hemodialysis circuit and dialysis arteriovenous access. (A) Normal goal treatment flow. Blood is “pulled” from the arterial line and after passing through dialyzer is returned via the venous line. Blood flow in the access (QA) is higher than that of the extracorporeal circuit (QB) and no recirculation is present. (B) Arteriovenous access recirculation caused by significant outlet stenosis. Because the outlet stenosis (triangles) causes low intraaccess flow (QA), returned blood via the venous line has higher flow than acceptable by the access. Blood flow is then directed to the area of the arterial line. Recirculation is calculated in this example to be 25%. (QA = access flow; QB = blood flow in the extracorporeal dialysis circuit; arrows depict the direction of blood flow; triangles depict stenosis.)

Figure 2

The team approach for managing a patient's vascular access. Cooperation and collaboration of the patient, nephrologist, dialysis nurse and technician, vascular access coordinator, interventionalist, and vascular surgeon are important to preserve the access.