Dialysis, also called hemodialysis, is the most common treatment for kidney failure.
A dialysis machine is an artificial kidney designed to remove impurities from your blood. During dialysis, blood is drawn from the patient through the
dialysis access already created and is connected to the dialysis machine so it can remove impurities and regulate fluid and chemical balances. The purified
blood is then returned to the patient again through the dialysis access. Creating the access portal is a minor surgical procedure. There are two types of
portals placed completely under the skin:
A surgeon creates an arteriovenous fistula by making a connection between an artery
(which carries blood away from the heart) and a vein (which carries blood back to the heart). This artificial connection allows the vein to become larger and
for the walls of the vein to thicken, a process termed maturation. A mature fistula makes it easier for the vein to be punctured repeatedly for dialysis.
Maturation typically takes three to six weeks to occur, but in rare cases, can takelonger. This makes advance planning for an arteriovenous fistula important.
When a patient is felt to be approximately a year away from requiring dialysis, the patient should be referred for evaluation for possible creation of an
arteriovenous fistula. Arteriovenous fistulas are usually created between radial artery and the vein at the wrist . it can also be done at the fore arm as
well as the elbow. An arteriovenous fistula is the preferred type of vascular access due to lower rate of infection and clot formation, resulting in greater
longevity than other types of vascular access. However, not everyone is a good candidate for an arteriovenous fistula, particularly older patients and patients
with small veins or those who have blocked veins in the upperlimb due to previous intravenous injections.
If a patient is not a good candidate for an arteriovenous fistula, an arteriovenous graft is
considered. An arteriovenous graft is a piece of artificial tubing, generally made out of teflon or fabric, that is attached on one end to an artery,
and on the other end to a vein. The tube is placed entirely under the skin and the tube itself is punctured during dialysis. An arteriovenous graft can
in general be used two to three weeks after the operation. However, arteriovenous grafts are more prone to infection and clotting than fistulas. The lifespan
of an arteriovenous graft is approximately two to three years.