Types of Dialysis

Dialysis is a way to remove waste products and extra water from the blood of patients with kidney failure. The two main types of dialysis are hemodialysis and peritoneal dialysis.

Hemodialysis diagram.

The Procedure 

In hemodialysis, your blood is removed from your body, a few ounces at a time, and it then flows through tubing and a dialyzer (or filter). The dialyzer is a canister that contains thousands of fibers that filter out the wastes and extra fluid. The clean blood is then returned to the body through different tubing. A machine will actually pump the blood from your body through the tubing and dialyzer.  Removing the harmful wastes and extra salt and fluids helps control blood pressure and keep the proper balance of chemicals like potassium and sodium in the body.

Adjusting to Hemodialysis 

One of the biggest adjustments when starting hemodialysis treatments is following a rigid schedule. Hemodialysis is usually performed in a clinic under the supervision of a nurse and kidney specialist, and is generally required three times a week for about three to four hours each treatment. For example, a Monday-Wednesday-Friday schedule or a Tuesday-Thursday-Saturday schedule is possible. In addition, a morning, afternoon, or evening shift will be dependent upon availability and capacity at the dialysis unit. Options for scheduling regular treatments will be discussed when the treatment begins. 

The other adjustment is that surgery must be performed to place “vascular access” so that blood can be readily removed for the procedure.  There are some options for vascular access that include creating a fistula (connecting an artery and vein in the arm), placing a graft (tubing that connects an artery to a vein), or placement of a dialysis catheter (a long tube with two separate openings placed into a large vein). 

The Procedure 

Peritoneal dialysis diagram.In peritoneal dialysis, a soft tube called a catheter is used to fill the abdominal cavity with a cleansing liquid called dialysate solution. The walls of the abdominal cavity are lined with a membrane called the peritoneum, which allows waste products and extra fluid to pass from your blood into the dialysate solution. The solution contains a sugar called dextrose that will pull extra fluid into the abdominal cavity.

These wastes and fluid then leave the body when the dialysate solution is drained and that used solution is then discarded. The process of draining and filling is called an "exchange" and may be done a few or several times each day, depending on the individual patient’s needs.  Peritoneal dialysis can be performed in the home, usually while the child sleeps, without a health professional present. Training is available under this circumstance.

Alternative Forms of Peritoneal Dialysis 

Different types of PD will have different schedules of daily exchanges.  One form of PD, continuous ambulatory peritoneal dialysis (CAPD), doesn't require a machine but exchanges may be done manually a few times during the day. As the word “ambulatory” suggests, the patient can walk around with the dialysate solution in the abdomen. Another form of PD, continuous cycler-assisted peritoneal dialysis (CCPD), requires a machine called a cycler to fill and drain the abdomen, usually at night while the patient is asleep. CCPD is also sometimes called automated peritoneal dialysis (APD).


Last Updated 11/2013