Dialysis: an introduction

End-stage renal disease (ESRD) or kidney failure is treated by dialysis or kidney transplant. There are two types of dialysis: hemodyalsis and peritoneal dialysis. In the US, hemodialysis is the most widely used treatment for ESRD and uremia (defined as elevated levels of urea and other nitrogen waste compounds in the blood) among people with diabetes. Hemodialysis is used by about 75% of people with ESRD and peritoneal dialysis by about 5%. About 18% of people with ESRD are treated with kidney transplant.1

Hemodialysis is a useful tool in the treatment of ESRD, even if it is not a long-term solution. It will extend life and function for a large percentage people who are affected by ESRD. However, kidney transplant is associated with higher long-term success rate, with 50% of kidney transplant patients alive after a decade.1

Hemodyalysis.Hemodialysis involves the use of a machine that serves the function of an artificial kidney to filter blood and remove waste products and excess fluids. In hemodialysis a connection is made to a blood vessel, typically in your arm, that allows blood to flow to and from the dialysis machine. In ESRD, hemodialysis is typically required three times per week for 4 to 5 hours each session and is usually performed in a hospital or a center dedicated to dialysis. Hemodialysis can be performed at home. Home dialysis provides the advantage of adapting the procedure to the individual’s schedule. Recent developments in dialysis include alternative dialysis schedules, such as daily dialysis (3 to 7 days per week, for 3 to 4 hours per session) and nighttime dialysis, where the procedure is performed while sleeping for 6 to 8 hours.1,2

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Prior to starting hemodialysis it is necessary to have a surgical procedure to create a point of access, where the blood will leave and return to your body. There are three different types of accesses use for hemodialysis: an AV fistula, an AV graft, and a central venous catheter. With an AV fistula, a vein in your arm is directly connected to an artery and two needle are inserted into the vein, one for removing blood and the other for returning it), an AV graft, and a central venous catheter. With an AV graft is similar to an AV fistula. Instead of directly connecting a vein to an artery, a very thin rubber hose inserted under the skin is used to connect the two vessels. With a central venous catheter, a thin, flexible tube is inserted into a large vein, usually in the neck, and is used to remove and return blood.2

Peritoneal dialysis. Peritoneal dialysis involves cycling a rinsing fluid (called dialysate) several times per day into the abdomen, where the fluid removes waste products from blood via small blood vessels present in the lining of the abdominal cavity. This type of dialysis is available for home use. The procedure requires insertion of a catheter into the abdominal cavity to facilitate infusion and draining of the dialysate to and from the cavity at regular intervals.1,3

The most common form of peritoneal dialysis is continuous ambulatory peritoneal dialysis (CAPD), in which the patient infuses and drains 2 liters of dialysate every 4 to 6 hours. Typically, there are 3 to 5 exchanges (draining and infusions) during the day, each taking about 30 to 40 minutes. Another form of peritoneal dialysis continuous cyclic peritoneal dialysis (CCPD) is performed by a machine while the patient is sleeping. CAPD can be effective if the person using this form of dialysis is highly motivated and capable and comfortable of being trained in administering the procedure. It provides advantages, including the lack of dependence on a machine, decreased stress on the cardiovascular system, and no requirement for use of the anti-clotting agent heparin. Peritoneal dialysis is associated with risk for peritonitis (infection of the abdominal lining) due to failure in adequate fluid exchange (infusion and draining).1,3

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Written by: Jonathan Simmons | Last reviewed: May 2014.