July 12, 2013

Kidney Dialysis, A Better Connection

Dialysis is a lifesaver, but there are complications when connecting elderly patients to the machines.

For elderly people with kidney failure, dialysis is a lifesaver. A four-year study of more than 115,000 dialysis patients 66 and older suggests that the method by which people are connected to dialysis machines may need to be reconsidered, particularly for those over 80.

When your kidneys can no longer filter the blood properly, you become a candidate for dialysis, filtration of the blood outside of the body. To work properly, dialysis machines need a high flow rate.

For people who expect to undergo repeat dialysis, it's best to surgically create a high-flow connection (called a fistula) between an artery and vein, usually in the forearm. During dialysis, the blood will leave the body through the artery, be cleansed by the dialysis machine then returned to the body through the vein.

Placement of a plastic catheter (tube) in a vein was found to be the most dangerous method. It was linked with a more than 74% increased risk of death in patients of any age.

Previous research clearly shows that a fistula made from the patient's own tissues is the best way to gain access to the blood for dialysis in younger individuals. An alternative, explored in the current study, is to use a graft, a plastic or Teflon tube, as the means of connecting to the dialysis machine.

The current study agrees that a patient's tissue is more durable and less prone to clotting or infection and is preferred for patients in their 60s and 70s. But for patients in their 80s and 90s, survival rates were similar with either a man-made graft or a fistula.

While the fistula has been preferred for years, there are advantages to using a graft. A fistula can't be used for dialysis until it matures, a process that generally takes three to six months and sometimes longer. A graft is ready to be used for dialysis in about two to six weeks. And fistulas are difficult to construct in people with small or thin veins. About a third of all fistulas fail during their first few weeks.

The study results suggest that rather than routinely opting for the fistula in elderly patients, the choice of whether to use a graft or a fistula in patients 80 and older should be tailored to the individual patient.

A third method of access to the blood, placement of a plastic catheter (tube) in a vein was found to be the most dangerous method. It was linked with a more than 74% increased risk of death in patients of any age. Catheters are used when dialysis is needed and the patient has no useable graft or fistula. They actually contain two separate tubes--one carries blood from the patient to the dialysis machine and the other returns blood to the circulation.

Catheters have long been known to be more prone to clotting problems and infections than grafts or fistulas. But for people with an immediate need for dialysis, they are often the best choice.

The study was published online in Journal of the American Society of Nephrology and will appear in a future print edition of the journal.

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