Dialysis is an artifical method of filtering the blood and is used when someone's kidneys have failed or are close to failing. Many people with late-stage kidney disease must go on dialysis either permanently or until a donor kidney for transplantation can be found.
Types of Dialysis
There are two types of chronic dialysis: hemodialysis and peritoneal dialysis.
In hemodialysis, the blood is pumped through a special machine that filters out waste products and fluid. Hemodyialysis is most commonly done during three sessions per week—each lasting three to five hours long—in a hospital, dialysis center, or at home, but it can also be done in shorter, more frequent sessions.
Several weeks or months before starting dialysis, most patients will have an artery and a vein surgically joined, typically in the forearm. This larger blood vessel is called a fistula, and it allows routine access to high blood flow by accessing an artery instead of a vein. Over time, the vein that is connected to the artery will begin to function more like an artery, and the access point for dialysis will be effective. An implanted tube, called an arteriovenous graft, can also be used for the same purpose if an artery and vein cannot be joined.
The most common side effects of hemodialysis are low blood pressure, muscle cramps, and itching.
In peritoneal dialysis, the peritoneum—the membrane of blood vessels lining the abdomen—stands in for the kidneys. A tube is implanted and used to fill the abdomen with a fluid called dialysate. Waste products in the blood flow from the peritoneum into the dialysate, which is then drained from the abdomen.
There are two forms of peritoneal dialysis: continuous ambulatory peritoneal dialysis, in which the abdomen is filled and drained several times during the day, and continuous cycler-assisted peritoneal dialysis, which uses a machine to cycle the fluid in and out of the abdomen at night while the patient sleeps.
The most common side effects of peritoneal dialysis are infections of the abdominal cavity or the site where the tube was implanted, weight gain, and hernia.
In addition, people on either form of dialysis still often experience complications caused by kidney failure such as anemia, bone weakening, and swelling or fluid accumulation in the heart or lungs.
In this condition, proteins are deposited on joints and tendons, causing pain and stiffness of the joints. Dialysis-related amyloidosis is common in people who have been on dialysis for five years or more.