Hemodialysis is the most common treatment for chronic kidney failure (end-stage renal disease). The procedure cleanses the blood of wastes and excess fluid after the kidneys can no longer perform these functions.

Blood is usually drawn through a needle inserted into the arm. The blood is sent through a dialysis machine that removes impurities and excess fluid. The cleansed blood is returned through another tube and needle.

The procedure lasts several hours and is typically performed three times a week. Most patients have hemodialysis at a clinic, but some receive training to handle the treatment at home or have a visiting caregiver perform the procedure.

Hemodialysis is the more widespread of the two types of dialysis. The other, peritoneal dialysis, involves use of a tube that has been permanently implanted in the abdomen.

Dialysis does not cure chronic kidney failure and usually continues for life unless a kidney transplant is possible. In rare cases, an individual with chronic kidney disease can be taken off hemodialysis because of improved kidney function.

Hospitals sometimes use hemodialysis short-term to treat acute kidney failure due to causes such as blood loss, poisoning or infection.

Hemodialysis cleanses the blood of toxins after the kidneys can no longer carry out this role well enough to keep the body from getting sick. Blood is usually drawn through a needle inserted into the arm. The blood is sent through a dialysis machine that removes impurities and excess fluid. The cleansed blood is returned to the body through another tube and needle.

Hemodialysis is the primary treatment for end-stage renal disease, the leading cause of which is diabetes (diabetic nephropathy). Usually the procedure is done at a dialysis center three times a week for two to four hours. Some patients undergo training to do it at home, which allows greater flexibility. However, these patients still must adhere to a schedule of treatments.

Hemodialysis is generally not painful. A common side effect, however, is fatigue due to anemia (insufficient red blood cells) and uremia (toxins in the blood that hemodialysis does not completely remove or that build up between treatments).

Ideally, weeks before the procedure begins, a surgeon prepares a site on the body (usually the arm) that will make it easier to draw blood. If hemodialysis must begin immediately, a tube called a catheter can be temporarily placed in a vein.

Treatment usually continues for life, and people requiring dialysis can die within weeks if they discontinue the treatments. Some studies have indicated that some people on dialysis have the potential to live without the treatments because of regained kidney function, but other research has reported a dangerous underuse of hemodialysis. Patients are advised to have their condition regularly and thoroughly monitored and are cautioned not to stop dialysis without a physician’s approval.

Hemodialysis is also used in hospitals to treat some cases of acute kidney failure. Causes of acute kidney failure include poisoning, trauma, vascular diseases and infections. Though hemodialysis does not cure chronic kidney failure, it can resolve some cases of acute failure.

Weeks or months before hemodialysis begins, a surgeon prepares a vascular access, the place on the body where blood is siphoned and returned. Having a site that allows good blood flow throughout treatment makes hemodialysis work better. There are three kinds of vascular access:

• Arteriovenous (AV) fistula.  A fistula is a connection between two parts of the body where normally there is no opening. The surgeon connects an artery to a vein, usually in the forearm, to allow greater blood flow into the strengthened vein. Often this is an outpatient procedure performed under local anesthesia.

The AV fistula is the preferred type of access for long-term hemodialysis because it lasts for years, allows a high volume of blood flow and has fewer complications, such as infection and clots. The disadvantage of this type of access is that it may take many months for the fistula to develop for use in dialysis.

• Arteriovenous graft. A tube is surgically inserted under the skin in the arm to serve as an artificial vascular access. An arteriovenous graft is usually the alternative option if an AV fistula is not possible (e.g., because the veins are too small). An AV graft often can be used within a few weeks. However, it tends to have greater risk of infection or clotting and to require replacement sooner than a fistula.
  
  A common complication of dialysis grafts is eventual blockage of the blood vessel due to growth of smooth muscle (intimal hyperplasia). Further surgery is needed to reopen the vessel. Researchers are studying use of gene therapy to prevent this obstruction.
  
  
• Venous catheter. A tube with two chambers allowing two-way flow of blood is placed into a vein in the neck, chest or thigh. Unlike the AV fistula and graft, the catheter does not require needles to be inserted into the body during hemodialysis. Because of complications including narrowing of the vein, the venous catheter usually is used as a temporary measure if immediate dialysis is necessary. If AV fistula or graft is not possible, a venous catheter can be used long term and is placed under the skin.

One complication of long-term hemodialysis is that patients may run out of healthy blood vessels that can serve as the vascular access. A potential solution is bioengineering. In late 2005, two hemodialysis patients in Argentina received the world’s first blood vessels grown in a laboratory from small samples of their own skin. Additional research is under way.

Most people receiving hemodialysis go to a clinic called a dialysis center, usually three times a week. Each dialysis session may last from three to five hours. Some centers offer other schedules, such as two-hour sessions six days a week. Needles are inserted at every session unless a venous catheter is being used. Usually two needles are used:

• One to carry blood to the dialysis machine
• One to return the cleansed blood to the body

There are also less-effective needles with dual openings for two-way exchange. Except for the needle sticks, the treatment is generally painless, though dialysis patients may be in pain because of complications such as severely impaired circulation in the legs. Patients who have the desire and ability to insert their own needles can be trained to do so. Needles are not used with the venous catheter because tubes connect the dialysis machine to the catheter.

During hemodialysis the patient lies down or relaxes in a recliner. Patients may pass the time by napping, reading, socializing or other activities. Sedentary pastimes have traditionally been encouraged during dialysis, but recent research suggests that low-intensity exercise during sessions, such as stationary cycling, can improve the removal of waste products and may enhance patients’ physical functioning.

The dialysis machine features a canister called a dialyzer that fills in for the kidneys’ filtering function. A dialysis solution (dialysate) that has been specifically prescribed for the patient is pumped around thousands of fibers in the dialyzer. The hemodialysis works as follows:

1. The patient’s blood is pumped into the dialysis machine.
   
   
2. Blood passes through the fibers and into the dialysis solution.
   
   
3. Chemicals in the solution absorb the impurities and excess fluids from the blood.
   
   
4. The solution carries away the impurities.
   
   
5. Clean blood is returned to the body.

The dialyzer may be reused, but only on the same patient and only after being cleaned, disinfected and tested before each use.

Employees at dialysis centers are trained in how to pretreat the water used in hemodialysis and cleansing of the dialyzer. Patients performing dialysis at home must follow instructions on how to pretreat tap water. Common disinfectants in water supplies, such as chlorine and chloramine, have to be removed in the prescribed manner before the water is used in dialysis machines. The contamination of dialysis water with even small amounts of these chemicals can cause hemolysis (breakdown of red blood cells). However, it is safe for dialysis patients to drink ordinary tap water, according to municipal utilities.

About once a month the dialysis center determines whether enough wastes are being removed from the blood. There are two tests that may be used to check for levels of a waste product called blood urea nitrogen (BUN):

• Residual renal function (RRF). A blood test and 24-hour urine collection revealing how well the kidneys are still working. The RRF test shows if kidney function has improved or deteriorated and if the hemodialysis prescription needs to be adjusted.
  
  
• Urea reduction ratio (URR). Compares urea in a predialysis blood sample to urea in a postdialysis blood sample. A percentage of 65 or higher is desired.
  
  
• Kt/V. A formula in which the dialyzer’s clearance in milliliters per minute (K) is multiplied by a hemodialysis session’s time in minutes (t). This number is then divided by the body’s volume of water (V) in liters. Volume is calculated at 60 percent of body weight in kilograms because water accounts for about 60 percent of a human’s weight. A Kt/V of 1.2 or higher is desired.

The Kt/V is more accurate than the URR in showing removal of urea because it also accounts for urea made by the body during hemodialysis and the extra urea removed during hemodialysis along with excessive fluid.

After undergoing hemodialysis, patients often experience fatigue. Some people, especially at first, feel a drop in blood pressure because of the volume of blood filtered. This hypotension can cause nausea, vomiting, cramps or headache. It is most common when first rising from the reclined position necessary for hemodialysis. Patients feeling symptoms of hypotension often feel better after lying back down for a while and then rising slowly.

The primary advantage of hemodialysis is the extension of life. People whose kidneys no longer work can die within weeks without dialysis or transplant.

Risks of hemodialysis include:

• Infection. The U.S. Centers for Disease Control and Prevention (CDC) notes that bacterial infections, particularly at the vascular access (site from which blood is drawn), cause considerable disease and mortality in hemodialysis patients. Catheters have greater risk of infection than arteriovenous fistulas and grafts, but use of catheters has increased.
  
  
• Clotting (thrombosis). The blood can thicken, solidify and block the vascular access. Clotting can be caused by a number of factors, including poor blood flow, compression of the site, drop in blood pressure and a technical problem with the site. Prevention and treatments include attending all hemodialysis sessions, having the blood flow through the vascular access routinely checked, avoiding compression of the access, restricting fluids and weight gain, and if necessary having angioplasty or surgical repair, according to the American Association of Kidney Patients.
  
  
• Low blood pressure (hypotension). Removal of too much fluid during hemodialysis can cause below-normal blood pressure, especially right after the procedure. The patient can ease hypotension by lying down or drinking liquids.
  
  
• Hemolysis (destruction of red blood cells). This rare but potentially dangerous side effect can result if chemicals such as chlorine and chloramine have not been removed from water used in dialysis machines, or if the tubing used is too narrow. Symptoms of hemolysis can include chest pain, abdominal pain, shortness of breath, nausea and vomiting.

Some problems common among people on hemodialysis are associated at least in part with chronic kidney failure itself. These conditions include high blood pressure (hypertension), itching, sleep disorders, abnormal heart rhythms (arrhythmias), anemia, amyloidosis (accumulation of proteins in joints and tissues) and renal osteodystrophy (weakened bones).

Anemia is common in dialysis patients, but some research has found many patients are being overtreated with anemia drugs. In 2007 the U.S. Food and Drug Administration tightened warning labels on these erythropoiesis-stimulating agents (ESAs) because of potential risks including heart attack and stroke. The agency recommends using the lowest dosage needed to avoid blood transfusions.

People on hemodialysis can often lead normal or nearly normal lives but have many responsibilities, particularly those with diabetes, lupus, high blood pressure or other complications. Factors include:

• Protecting the vascular access (site from which blood is drawn). People on hemodialysis often have minor surgery on a blood vessel in the arm or a device implanted to make dialysis easier. Patients must take care of the vascular access to help prevent infection and other problems. Care includes keeping the site clean, using an unaffected arm for checking blood pressure, guarding against injury and pressure such as from tight clothing or jewelry, and avoiding heavy lifting with an affected arm.
  
  
• Schedule. These time-consuming treatments will cause major changes in the patient’s routine. Transportation is a major issue for some. Hemodialysis patients often need to reduce their responsibilities but can continue to work except for heavy labor. Working on a computer and reading are productive ways to spend the hours during treatment.

Clinics may offer appointments at night or early morning. Home hemodialysis done by the patient, visiting nurse or dialysis technician might be options. Some patients may prefer hemodialysis six days a week for two hours rather than conventional hemodialysis thrice a week for three to four hours. Home hemodialysis and some hemodialysis centers may offer this option.

• Controlling glucose (blood sugar). Keeping glucose within the range prescribed by the physician is important for all people with diabetes but is especially crucial for those undergoing dialysis. Recent long-term research suggests that hemodialysis patients’ glycohemoglobin test results, a measure of long-term glucose control, can be an independent predictor of survival and quality of life.

Both forms of dialysis (hemodialysis and peritoneal dialysis) involve additional concerns. These include diet, depression and stress, expense and end-of-life decision making.

In addition to the variations of vascular access for hemodialysis, there is a type of hemodialysis called high-flux dialysis or high-efficiency dialysis. Using dialyzers with larger pores, this newer method not only does a better job of removing the waste material blood urea nitrogen (BUN) but also gets rid of larger molecules. These molecules can cause difficulties with some patients and may be not be removed by conventional dialysis, according to the Kidney Transplant/Dialysis Association.

High-flux treatments can take up to 25 percent less time. A disadvantage can be fever caused by dead bacteria that pass through the larger pores.    

Some dialysis centers offer instruction on how to perform hemodialysis at home. A relative or friend who will assist with the dialysis must also take the training, which typically lasts a month or more. The patient needs space to store the machine and supplies, often in a spare bedroom. Medicare usually covers 80 percent of the cost of home hemodialysis. Medicaid, private insurance or state programs frequently cover the remaining expense.

The length and number of home hemodialysis sessions can vary, but it is vital to maintain the schedule of treatments.

Repeated studies have found longer survival and higher quality of life among the 2 percent of people using home hemodialysis rather than a dialysis center. Home hemodialysis offers greater convenience and independence and costs thousands of dollars less annually. One study found five-year survival rates of 90 percent, which was 2.5 times better than that of people using hemodialysis centers.

The National Kidney Foundation found that people doing their hemodialysis at home often stay in the workforce because scheduling is more flexible than at a dialysis center. However, some people prefer the social support or structure provided by a hemodialysis center. Others are unable to perform the procedure themselves or have no one to assist them at home.

Besides hemodialysis, there is a second major type of dialysis called peritoneal dialysis. Usually carried out at the patient’s home, peritoneal dialysis uses a tube surgically implanted in the abdomen. Dialysis solution supplied through the tube remains in the abdomen for several hours. The dialysate draws wastes and extra fluids that leave the body when the solution is drained. Several sessions a day are usually required. Often people on dialysis can switch from hemodialysis to peritoneal and vice versa.

The only alternate treatment for people requiring long-term dialysis is a kidney transplant. However, people with acute kidney failure can in many cases be treated instead with methods such as intravenous fluids, diuretics or antibiotics. 

The best course for people with risk factors for kidney diseases such as diabetic nephropathy or lupus nephritis is to avert and the need for hemodialysis through preventive measures and early and careful monitoring. Prevention may includes diet and exercise, special testing by the physician for protein in the urine (microalbuminuria test), and control of glucose and blood pressure. Patients may be prescribed medications that can protect against kidney disease, such as ACE inhibitors, angiotensin-II receptor blockers or other antihypertensives.

Preparing questions in advance can help patients have more meaningful discussions with their physicians regarding their conditions. Patients may wish to ask their doctor the following questions about hemodialysis:

1. Do I need or am I at risk of needing dialysis?
   
   
2. Can anything be done to prevent or delay my need for dialysis?
   
   
3. What are the advantage and disadvantages to me of hemodialysis compared to peritoneal dialysis?
   
   
4. How often will my hemodialysis take place, and how long will my sessions be?
   
   
5. What kind of vascular access will be used? How will my site be prepared?
   
   
6. Can my hemodialysis be done at home, or do I need to go to a dialysis center?
   
   
7. If I do my hemodialysis at home, what sort of training is needed? Is a helper necessary? How do I need to pretreat the water used in my machine?
   
   
8. Will my hemodialysis cause me any pain? How tired am I likely to feel afterward?
   
   
9. What changes in my diet and other habits does hemodialysis require?
   
   
10. Can I work and enjoy other activities while undergoing hemodialysis? Is exercise during my sessions beneficial?
    
    
11. What sort of financial, transportation and emotional support is available to me?
    
    
12. What kind of testing is needed to monitor my kidney function, glucose control and effectiveness of my hemodialysis? How often do I need to have these tests?
    
    
13. What can be done if I run out of healthy blood vessels that can be used for my vascular access?
    
    
14. Should I complete a living will and other such documents?
    
    
15. What are the chances that I can regain enough kidney function to survive without hemodialysis?
    
    
16. Is a kidney transplant or other treatment a possible alternative?