Hemodialysis
Now that you know how PD works, let's talk about the kind of dialysis you may have heard about.
Hemodialysis, or HD, cleans the blood by using a filter called a dialyzer (dye'-uh-lizer). Inside the dialyzer are thousands of hollow fibers as thin as hairs—punctured with millions of tiny holes.
During HD, blood moves through the inside of the fibers. Blood cells and proteins that are needed by the body are too big to pass through the holes. They stay in the blood. Wastes and extra water go through the holes and into dialysate fluid that is thrown away.
HD is most often done three times a week in a center, for about 4 hours each treatment. Longer is better. Here's why: healthy kidneys work 24 hours a day, 7 days a week (168 hours)—but in-center dialysis may work about 12 hours a week. The more HD time, the better people feel. The doctor will prescribe the amount of HD time.
Test Your Knowledge
Can you guess how much blood is outside of the body at any given time during HD?
1 cup
1 pint
1 quart
1 gallon
You're right! The dialysis machine cleans only a small amount of blood at any one time (about one cup).
That's not the correct answer. Please try again!
What Are the Types of Vascular Access?
A vascular access is the way that blood goes out of your body to be cleaned, and then returns to your body. There are three main types of access:
Fistula: An artery and a vein are surgically linked to each other. Fistulas are most often placed in an arm. This is the best type of access.
Graft: A man-made vein is used to surgically link an artery to a vein. Grafts can be placed in an arm or a leg.
Catheter: A Y-shaped plastic tube is placed into a large vein in the chest, neck, or groin. Because there is a high risk of infection, catheters are used for a short time unless there is no other choice.
Fistulas are the best type of access because they last longer and are less likely to clot or become infected. To learn more about vascular access, read Module 8—Vascular Access: A Lifeline for Dialysis.
