Hemodialysis (he-mo-di-AL-uh-sis) is a way to remove waste products from the blood when the kidneys can no longer do their job adequately. In hemodialysis, a machine filters wastes, salts and fluid from the blood. Hemodialysis is the most common way to treat kidney failure.

How does Hemodialysis Work?

In hemodialysis, blood is removed from the body and filtered through a filter called a dialyzer, or artificial kidney, and the filtered blood is returned to the body. To perform hemodialysis, there needs to be an access point in the patient’s body to get the blood from the body to the dialyzer and back into the body. There are three types of access points for hemodialysis: arteriovenous (AV) fistula, AV graft, and central venous catheter (HD cath). The fistula is the most common access used in adult patients and the central venous catheter is the most common access used in children.

When a patient goes to receive hemodialysis, a nurse checks vital signs and gets the patient’s weight. The patient’s weight will indicate how much excess fluid the patient needs to have removed during the treatment. The patient is then connected to the machine.

Blood never actually goes through the dialysis machine. The machine is like a big computer and a pump. It keeps track of blood flow, blood pressure, the amount of fluid removed, and other vital information. It also mixes the dialysate, or dialysis solution, which is the fluid bath that goes into the dialyzer. This fluid helps pull toxins from the blood. The dialysis machine has a blood pump that keeps the blood flowing by creating a pumping action on the blood tubes that carry the blood from the body to the dialyzer and back to the body.

The dialyzer, or filter, is the key to hemodialysis. The dialyzer is a hollow plastic tube about a foot long and three inches in diameter that contains many tiny filters. There are two sections in the dialyzer: the section for dialysate, and the section for the blood. The two sections are divided by a semipermeable membrane to prevent mixing. The membrane allows the dialysate and waste to pass through, but does not allow blood cells to pass through. The dialysis solution is then flushed down the drain along with the waste. The electrolytes in the dialysis solution help balance the electrolytes in the patient’s blood. Once it is filtered, it is then returned to the patient’s body.

What are the Different Forms of Hemodialysis?

There are three ways hemodialysis can be performed:

In-Center Hemodialysis

All children and many adults receive hemodialysis at a dialysis center where a nurse performs the tasks required during treatment. In-center hemodialysis is usually done three times a week for around three to four hours per session. In-center treatments are done at pre-scheduled times.

Home Hemodialysis

Some adults have begun doing hemodialysis treatments in the comfort of their own home. Patients and their caretakers are trained to do dialysis safely and handle any issues that may arise. Home hemodialysis can be done in several different ways. Conventional home hemodialysis is done three times a week for three to four hours per session, much like an in-center treatment. Another way to do home hemodialysis is in short cycles where the patient performs 5 to 7 shorter sessions during the week.  These treatments are shorter and last about two hours each.  Because dialysis is being done more frequently, less fluid generally needs to be removed each session.

Nocturnal Hemodialysis

Nocturnal hemodialysis can be done in-center or at home.  These sessions are slow treatments (over 6 to 8 hours) done at night while sleeping. Patients generally receive nocturnal hemodialysis 3 to 6 nights each week depending on how their bodies respond.

Sometimes patients may combine daily and nocturnal hemodialysis depending on their medical needs.

What are the Advantages and Disadvantages of Hemodialysis?

The benefits of hemodialysis include:

  • Nurses perform treatments for the patient
  • Regular contact with other hemodialysis patients and staff
  • Patients usually only have three treatments per week; giving them four days off
  • No equipment or supplies have to be kept at home
  • In an emergency, medical help is available quickly

The disadvantages of hemodialysis include:

  • Travel to a dialysis center may be required three times a week
  • Patients may not be able to set their own treatment schedule
  • Permanent access required; usually in the arm for adults and the neck/chest area for children
  • Needles are required to access a fistula
  • Access sites run the risk for infection
  • Strict renal diet and fluid restrictions are required
  • Some patients experience discomforts such as headaches, nausea, leg cramps, tiredness, and weakness

How do I Prepare for Hemodialysis?

Before hemodialysis begins, your team will need to place an access line (fistula, AV graft, or central venous catheter). The surgical access needs time to heal before you begin hemodialysis treatments. In some cases, an emergency line (central venous catheter) will be placed and used immediately.

If you are doing in-home hemodialysis, you will receive intensive training on what the procedure involves and how to use the equipment safely.  You will also meet with a dialysis nurse and nutritionist.  It may be a good idea to also have a family member trained to help you. Be sure to find out your new dietary and fluid restrictions with the nutritionist. Visit our ‘Diet and Nutrition’ tab for more information on a renal diet.

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