Patient information: Hemodialysis

HEMODIALYSIS OVERVIEW

Dialysis is a treatment for severe kidney failure (also called renal failure, stage 5 chronic kidney disease, and end-stage renal disease). When the kidneys are no longer working effectively, waste products and fluid build up in the blood. Dialysis take over a portion of the function of the failing kidneys to remove the fluid and waste. (See "Patient information: Dialysis or kidney transplantation — which is right for me?".)

Dialysis is typically needed when about 90 percent or more of kidney function is lost. This usually takes many months or years after kidney disease is first discovered. Early in the course of kidney disease, other treatments are used to help preserve kidney function and delay the need for replacement therapy. (See "Patient information: Chronic kidney disease".)

WHICH TYPE OF DIALYSIS IS BEST?

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

• Hemodialysis (in-center or at home)
• Peritoneal dialysis (see "Patient information: 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 healthcare provider. (See "Patient information: Dialysis or kidney transplantation — which is right for me?".)

WHEN TO START DIALYSIS

You and your doctor will make the decision about when to start dialysis as your kidney disease progresses. 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. Healthcare providers recommend that dialysis begin well before kidney disease has advanced to the point where life threatening complications can occur.

It is generally possible to be put on a kidney transplant waiting list when kidney function is about 20 percent of normal. Many patients will need to start dialysis when their kidney function is about 8 to 12 percent of normal, although this is variable.

In certain situation, dialysis must be started immediately. If blood tests indicate the kidneys are working very poorly or not at all, or if there are symptoms such as confusion or bleeding that is related to kidney disease, dialysis should be started at once.

PREPARING FOR HEMODIALYSIS

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 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 access. Having an intravenous line (IV) 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 non-dominant arm; for a right-handed person this would be their left arm.

After the access is placed, it is important to monitor and care for it over time. (See 'Caring for the access' below.)

Primary AV fistula — A primary AV fistula is the preferred type of vascular access. It requires a surgical procedure that creates a direct connection between an artery and a vein (figure 1). This is often done in the lower 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 tube to create a path between an artery and vein (figure 2). 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 about two 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) (figure 3). 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 to 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 dialysis 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. (See "Patient information: Low sodium diet" and "Patient information: Low potassium diet".)

LOCATION OF HEMODIALYSIS TREATMENT

Hemodialysis can be done at a dialysis center or at home.

Home treatment — Home treatment requires that you and your family have training and ongoing support from healthcare providers who are experienced in treating patients with home hemodialysis. This usually includes a nephrologist (kidney specialist) and specially trained nurses.

Patients treated with home hemodialysis can often lead more independent lives and may have improved survival outcomes compared to those treated in a dialysis center. This is due, in part, to home hemodialysis patients having more frequent or longer dialysis treatments than those treated in a dialysis center.

Home dialysis is generally done three to seven times per week and takes between three and ten hours per session. Hemodialysis that is done during the daytime is often done for about three to four hours, four to seven days each week. Hemodialysis that is done at night (called nocturnal hemodialysis) is typically done three to seven times weekly while you are sleeping. Additional time is needed to prepare and clean up.

Home dialysis can be done at a time that is convenient for you. You are generally required to have someone else (a family member, friend, or technician) to assist you before, during, and after dialysis. A healthcare provider must be available by telephone in case questions or problems arise; some machines allow you to be monitored remotely via the telephone or internet.

A daily (or nightly) dialysis schedule provides substantial benefits compared to in-center, three times weekly hemodialysis. More frequent dialysis results in a significant improvement in your well being, reduces symptoms during and between dialyses, and improves quality of life. Home hemodialysis can improve your quality of life because it allows you to assume more responsibility for your own care and allows you to remain in the comfort of your home during treatment. In addition, patients who use home hemodialysis are often able to continue working.

Equipment — Home hemodialysis requires that you have a dialysis machine in your home. Depending upon the machine, additional supplies may be needed, including water treatment tanks, dialyzers, bottles of dialysate, bleach and disinfectant, syringes, needles, medications, blood tubes, and water test kits. Some machines require electrical and plumbing modifications in the area of the home where dialysis will be done. Currently available home hemodialysis machines are approximately the size of a bedside table.

Newer home hemodialysis systems are portable and can be used while traveling, although many patients who use home hemodialysis and wish to travel make arrangements for in-center dialysis at the location where they will be traveling (see 'Travel options' below.

Dialysis center treatment — Dialysis may be done in a hospital, a clinic associated with a hospital, or a free-standing clinic. Centers are staffed with physicians, nurses, and patient care technicians, all of whom participate in your care. In general, in-center hemodialysis takes between three and five hours (the average is three and a half to four hours) and is done three times a week. You will be able to read or sleep during treatment, and you usually have access to a television. Eating, drinking, and visitors are usually restricted in a dialysis center.

Travel options — Dialysis centers are located throughout the United States and in many locations around the world. Patients who require dialysis but wish to travel can make an appointment at a dialysis center in the location where they will be traveling (called a transient center). Many dialysis centers have a staff member, either a nurse or social worker, who can help arrange the appointment; planning should begin six to eight weeks in advance to ensure that space is available.

The dialysis center where you normally have dialysis treatments will need to provide information to the transient center about your medical history, including recent test results and treatment records, a list of medications, insurance information, and any special requirements.

Patients with chronic medical problems, including those who require dialysis, should plan carefully for travel away from home. This may include carrying extra medications and written prescriptions, a medical identification device, and a list of healthcare provider contact information. (See "Patient information: General travel advice".)

HEMODIALYSIS MONITORING

Blood testing — Patients who use hemodialysis, either at home and in-center, will be monitored with blood tests to ensure that the time and type of dialysis treatments (called dialysis prescription) are optimal. Studies have shown that the correct dialysis prescription improves health, prevents complications, and prolongs survival. Blood testing is done at least once per month, and adjustments to the dialysis prescription may be made based upon the results of testing.

Body weight monitoring — Because kidneys that are failing cannot remove enough fluid from the body, dialysis must perform this task. Accumulation of fluid between hemodialysis treatments can lead to complications. Most patients will be weighed before and after dialysis, and will be asked to monitor their weight on a daily basis at home. If your weight increases more than usual between treatments, contact your healthcare provider.

Caring for the access — It is important to take care of your access to prevent complications. Complications can occur even if you are careful, but are much less common if you take a few precautions:

• Wash the access with soap and warm water each day, and always before dialysis. Do not scratch the area or try to remove scabs.
• Check the area daily for signs of infection, including warmth and redness.
• Check that there is blood flow in the access daily. There should be a vibration (called a thrill) over the access. If this is absent or changes, notify your healthcare provider. Sometimes, flow monitoring is done during the dialysis treatment using ultrasound (sound waves). The flow monitoring measures the speed of blood flow during dialysis treatment.
• Take care to avoid traumatizing the arm where the access is located; do not wear tight clothes, jewelry, carry heavy items, or sleep on the arm. Do not allow anyone to take blood or measure blood pressure on this arm.
• Rotate needle sites on the access. Use gentle pressure to stop bleeding when the needle is removed. If bleeding occurs later, apply gentle pressure; call a healthcare provider if bleeding does not stop within 30 minutes or if bleeding is excessive.

SIDE EFFECTS

Most patients tolerate hemodialysis well. However, side effects of hemodialysis can occur. Low blood pressure is the most common complication and can be accompanied by lightheadedness, shortness of breath, abdominal cramps, muscle cramps, nausea, or vomiting.

Treatments and preventive measures are available for the discomforts that can occur during dialysis. Many of these side effects are related to excess salt and fluid accumulation between dialysis treatments, which can be minimized by carefully monitoring how much salt and fluid you consume.

WHERE TO GET MORE INFORMATION

Your healthcare provider is the best source of information for questions and concerns related to your medical problem. Because no two people are exactly alike and recommendations can vary from one person to another, it is important to seek guidance from a provider who is familiar with your individual situation.

This discussion will be updated as needed every four months on our web site (www.uptodate.com/patients). Additional topics as well as selected discussions written for healthcare professionals are also available for those who would like more detailed information.

Some of the most pertinent include:

Patient Level Information:
Patient information: Dialysis or kidney transplantation — which is right for me?
Patient information: Chronic kidney disease
Patient information: Peritoneal dialysis
Patient information: Low sodium diet
Patient information: Low potassium diet
Patient information: General travel advice

Professional Level Information:
Acute hemodialysis prescription
Assessment of nutritional status in end-stage renal disease
Cancer screening in patients with end-stage renal disease
Chronic hemodialysis vascular access: Types and placement
Dialysis modality and patient outcome
Indications for initiation of dialysis in chronic kidney disease
Kt/V and the adequacy of hemodialysis
Overview of the hemodialysis apparatus
Patient survival and maintenance dialysis
Prescribed versus delivered dialysis: Importance of dialysis time
Reactions to the hemodialysis membrane
Reuse of dialyzers
Thrombotic complications of chronic hemodialysis vascular access: Fistulas and grafts
Urine output and residual renal function in renal failure

A number of web sites have information about medical problems and treatments, although it can be difficult to know which sites are reputable. Information provided by the National Institutes of Health, national medical societies and some other well-established organizations are often reliable sources of information, although the frequency with which they are updated is variable.

• National Library of Medicine

      (www.nlm.nih.gov/medlineplus/healthtopics.html)

• National Institute of Diabetes and Digestive and Kidney Diseases

      (www.niddk.nih.gov)

• National Kidney Foundation

      (800) 922-9010
      (www.kidney.org)

• Home Dialysis Central

      (www.homedialysiscentral.org)

• Kidney School

     (www.kidneyschool.org)

• United Network for Organ Sharing (UNOS)

      (888) 894-6361
     (www.unos.org)

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