Dialysis is typically needed when approximately 90 percent or more of kidney function is lost. Kidney function can be lost rapidly (acute kidney injury) or over months or years (chronic kidney disease). Early in the course of kidney disease, other treatments are used to help preserve kidney function and delay the need for replacement therapy.

Type of Dialysis

Once dialysis becomes necessary, you (along with your clinicians) should consider the advantages and disadvantages of the two types of dialysis:

●Hemodialysis (in center or at home)

●Peritoneal dialysis

The choice between hemodialysis and peritoneal dialysis is influenced by a number of issues, such as availability, convenience, underlying medical problems, home situation, and age. This choice is best made by discussing the risks and benefits of each type of dialysis with a health care provider. Patients with chronic kidney disease should also discuss the possibility of getting a kidney transplant with their clinicians.

Starting Dialysis

You and your doctor will make the decision about when to start dialysis. Your kidney function (as measured by blood and urine tests), overall health, nutritional status, symptoms, quality of life, personal preferences, and other factors impact the decision regarding the timing of initiation of dialysis. Dialysis should begin well before kidney disease has advanced to the point where life-threatening complications can occur.

The amount of kidney function you have is generally estimated by using the results of a common blood test called the serum creatinine to calculate an estimated glomerular filtration rate (eGFR) level. The higher the creatinine level in the blood, the lower your amount of kidney function or GFR. It is generally possible to be put on a kidney transplant waiting list when kidney function is approximately 20 percent of normal. Many patients will need to start dialysis when their kidney function is approximately 6 to 10 percent of normal, although this is variable. Most patients will have some symptoms at this low level of kidney function; starting dialysis will often improve these symptoms. Most patients do not really need to start dialysis until they have some symptoms, and there is not a definite level of kidney function at which it is necessary to start dialysis in the absence of symptoms, although some nephrologists (kidney specialists) recommend dialysis, even in the absence of symptoms, once the eGFR level falls below approximately 10 mL/min/1.73 m² (which is how labs report this number). Patients with chronic kidney disease and some with acute kidney injury have a normal amount of urine, but the urine does not get rid of the body’s waste products.

If blood tests indicate that the kidneys are working very poorly or not at all; if there are dangerous blood chemistry values, such as a very high blood potassium concentration; or if there are symptoms such as confusion or bleeding that is related to kidney disease, dialysis should be started at once.

Hemodialysis

For patients with chronic kidney disease, preparations for hemodialysis should be made at least several months before it will be needed. In particular, you will need to have a procedure to create an “access” (described below) several weeks to months before hemodialysis begins.

Vascular access — An access creates a way for blood to be removed from the body, circulate through the dialysis machine, and then return to the body at a rate that is higher than can be achieved through a normal vein. There are three major types of access: primary arteriovenous (AV) fistula, synthetic AV bridge graft, and central venous catheter. Other names for an access include a fistula or shunt.

The access should be created before hemodialysis begins because it needs time to heal before it can be used. Discussions about the access should begin even earlier since you will need to avoid injuring blood vessels that will eventually be used for the access. Having an intravenous (IV) line or frequent blood draws in the arm that will be used for access can damage the veins, which could prevent them from being used for a hemodialysis access. The access is usually created in the nondominant arm; for a right-handed person this would be his or her left arm.

After the access is placed, it is important to monitor and care for it over time.

Primary arteriovenous fistula — A primary AV fistula is the preferred type of vascular access for most patients. It requires a surgical procedure that creates a direct connection between an artery and a vein. This is often done in the lower portion of the nondominant arm but can be done in the upper arm as well. Sometimes, a vein that would not normally be useful for creating an AV fistula can be moved so that it is more accessible; this is often done in the upper arm.

Regardless of its location or how it is created, the access is located under the skin. During dialysis, two needles are inserted into the access. Blood flows out of the body through one needle, circulates through the dialysis machine, and flows back into the access through the other needle.

A primary AV fistula is usually created two to four months before it will be used for dialysis. During this time, the area can heal and fully develop or “mature.”

Synthetic bridge graft — Sometimes, a patient’s arm veins are not suitable for creating a fistula. In these cases, a surgeon can use a flexible, rubber-like tube to create a path between an artery and vein. This is called a synthetic bridge graft. The graft sits under the skin and is used in much the same way as the fistula, except that the needles used for hemodialysis are placed into the graft material rather than the patient’s own vein.

Grafts heal more quickly than fistulas and can often be used approximately two to three weeks after they are created. However, complications such as narrowing of the blood vessels and infection are more common with grafts than with AV fistulas.

Central venous catheter — A central venous catheter uses a thin, flexible tube that is placed into a large vein (usually in the neck). It may be recommended if dialysis must be started immediately and the patient does not have a functioning AV fistula or graft. This type of access is usually used only on a temporary basis. In some cases, however, there can be problems maintaining an AV fistula or graft, and the central venous route is used for long-term access.

Catheters have the highest risk of infection and the poorest function compared with other access types; they should be used only if a primary fistula or synthetic bridge graft cannot be maintained.

Dietary changes — Some patients, especially those who receive hemodialysis in a center, will need to make changes in their diet before and during hemodialysis treatment. These changes ensure that you do not become overloaded with fluid and that you consume the right balance of protein, calories, vitamins, and minerals.

A diet that is low in sodium, potassium, and phosphorus may be recommended, and the amount of fluids (in drinks and foods) may be limited. A dietitian can help you to choose foods that are compatible with hemodialysis treatment.

Peritoneal Dialysis

During peritoneal dialysis, a cleansing fluid flows through a tube into part of the stomach area, also called the abdomen. The inner lining of the abdomen, known as the peritoneum, acts as a filter and removes wastes from blood. After a set amount of time, the fluid with the filtered waste flows out of the abdomen and is thrown away.

Because peritoneal dialysis works inside the body, it’s different from a more-common procedure to clean the blood called hemodialysis. That procedure filters blood outside the body in a machine.

Peritoneal dialysis treatments can be done at home, at work or while you travel. But it’s not a treatment option for everyone with kidney failure. You need to be able to use your hands in a skillful way and care for yourself at home. Or you need a trusted caregiver to help you with this process.

Which Type Of Dialysis Is Best For You

Talk with our specialist about which type of dialysis might be best for you. Factors to think about include your:

• Kidney function.
• Overall health.
• Personal preferences.
• Home situation.
• Lifestyle.

Peritoneal dialysis may be the better choice if you:

• Have trouble coping with side effects that may happen during hemodialysis. These include muscle cramps or a sudden drop in blood pressure.
• Want a treatment that’s less likely to get in the way of your daily routine.
• Want to work or travel more easily.
• Have some leftover kidney function.

Peritoneal dialysis might not work if you have:

• Scars in your abdomen from past surgeries.
• A large area of weakened muscle in the abdomen, called a hernia.
• Trouble caring for yourself, or a lack of caregiving support.
• Some conditions that affect the digestive tract, such as inflammatory bowel disease or frequent bouts of diverticulitis.

In time, it’s also likely that people using peritoneal dialysis will lose enough kidney function to need hemodialysis or a kidney transplant.