Dialysis Access Creation/Maintenance Q & A

Dialysis Access is another common reason patients visit the office. The vascular surgeon is involved in providing access to dialysis.The simplest way to explain dialysis is to describe it as removing naturally occurring substances, excess water, and dissolved products of metabolism, from the blood by a process of diffusion and filtration. The need for dialysis occurs when the kidneys no longer function properly; the need may be the short or long term. The two main ways of receiving dialysis are hemodialysis and peritoneal dialysis. In both methods, there is a semi-permeable membrane which allows for the passage of water and dissolved substances from areas of high concentration (the blood of the patient) to areas of low concentration, the dialysate fluid. A semipermeable membrane allows the passage of some substances while inhibiting the passage of others.

Catheters for hemodialysis often referred to by the generic term Perm-cath, are typically double barrel plastic tubes inserted into one of the large veins of the body to allow for the removal and reinfusion of large volumes of blood. Peritoneal dialysis catheters are typically single barrel and are placed through the wall of the abdomen into the abdominal cavity. Catheters have the advantage of being available for use upon insertion and aside from the discomfort of insertion, are associated with minimal discomfort during dialysis. The downside is that it leaves the patient with an externally protruding catheter, makes bathing difficult, and are prone to infection and clotting. These are placed by vascular surgeons, interventional radiologists, general surgeons, and some nephrologists.

AV (arteriovenous) fistulas and AV grafts are surgical procedures that are performed primarily by vascular surgeons but also some general surgeons. In creating an AV fistula, a vein in the arm is directly connected to an artery. The high-pressure high flow of arterial blood shunted into the vein causes the vein to dilate and thicken. This then allows the dialysis nurse to place needles in the vein to both withdraw and reinfuse blood for dialysis. An AV graft creates this connection from the artery to the vein using a plastic tube which is placed beneath the skin. The drawback for both is that there is some minor pain involved with the placement of needles although this tends to lessen over time. AV fistulas require 8 to 12 weeks to mature before use; AV grafts 2 to 3 weeks. Fistulas are more desirable in that they are less prone to clotting, have a lower infection rate, and when not being dialyzed there is nothing external to interfere with the activities of daily living. AV grafts have a slightly higher infection rate and clotting rate than AV fistulas but there is nothing external when not being dialyzed.

The current recommendation is that the majority of patients receiving hemodialysis should be dialyzed by fistulas with less by AV grafts and least by catheters as catheters provide the most complications. Your doctor may refer you prior to needing hemodialysis when your kidneys have a borderline function to avoid ever having the need for a catheter. 

The average dialysis patient may require 1 to 2 interventions per year to maintain their access.

The type of dialysis you receive is a decision to be made between you and your kidney doctor.