Hemodialysis

While healthy kidneys have several functions in the body, the most well-known job is to produce urine. When kidney function goes below 10% to 15% kidneys are no longer able to filter the blood and make urine. This causes toxins to build up in the body along with excess fluid. Fortunately, we live in a time when there are treatments and medicines that can replace the functions of the kidneys and keep the body alive. One type of renal replacement therapy — meaning a treatment that replaces kidney function — is hemodialysis. Hemodialysis is a therapy that filters waste, removes extra fluid and balances electrolytes (sodium, potassium, bicarbonate, chloride, calcium, magnesium and phosphate).

How is hemodialysis done?

In hemodialysis, blood is removed from the body and filtered through a man-made membrane called a dialyzer, or artificial kidney, and then the filtered blood is returned to the body. The average person has about 10 to 12 pints of blood; during dialysis only one pint (about two cups) is outside of the body at a time. To perform hemodialysis there needs to be an access created to get the blood from the body to the dialyzer and back to the body. There are three access types for hemodialysis: arteriovenous (AV) fistula, AV graft and central venous catheter. The AV fistula is the vascular access most recommended by the dialysis community; however, you and your doctor will decide which access is best for you.

When a patient goes to hemodialysis, a nurse or technician will check vital signs and get the patient’s weight. The weight gain will tell how much excess fluid the patient has to have removed during the treatment. The patient is then “put on the machine”. Patient with a vascular access (AV fistula or AV graft) will get two needle sticks in their access; one needle takes blood out of the body, the other needle puts it back. Patients with a central venous catheter will have the two tubes from their access connected to the blood tubes that lead to the dialyzer and back to the body. Once the patient is “put on the machine”, the dialysis machine is programmed and then treatment begins.

Blood never actually goes through the dialysis machine. The dialysis machine is like a big computer and a pump. It keeps track of blood flow, blood pressure, how much fluid is removed and other vital information. It mixes the dialysate, or dialysis solution, which is the fluid bath that goes into the dialyzer. This fluid helps pull toxins from the blood, and then the bath goes down the drain. 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 dialysis machine also has many safety detection features. If you visit a dialysis center, you will likely hear some of the warning sounds made by a dialysis machine.

How does hemodialysis work?

The dialyzer is the key to hemodialysis. The dialyzer is called the artificial kidney because it filters the blood — a job the kidneys used to do. The dialyzer is a hollow plastic tube about a foot long and three inches in diameter that contains many tiny filters. (Dialyzers are made in different sizes so doctors can prescribe the best one for their patients.) 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 so that they don’t mix together. A semipermeable membrane has microscopic holes that allow only some substances to cross the membrane. Because it is semipermeable, the membrane allows water and waste to pass through, but does not allow blood cells to pass through.

Dialysate, also called dialysis fluid, dialysis solution or bath, is a solution of pure water, electrolytes and salts, such as bicarbonate and sodium. The purpose of dialysate is to pull toxins from the blood into the dialysate. The way this works is through a process called diffusion. In the blood of the hemodialysis patient, there is a high concentration of waste, while the dialysate has a low concentration of waste. Due to the difference in concentration, the waste will move through the semipermeable membrane to create an equal amount on both sides. The dialysis solution is then flushed down the drain along with the waste. The electrolytes in the dialysis solution are also used to balance the electrolytes in the patient’s blood. The extra fluid is removed through a process called filtration. The fluid is pushed off by higher pressure on the blood side than on the dialysate side.

How often is hemodialysis done?

Blood needs to flow through the dialyzer for several hours to adequately clean the blood and rid the body of excess fluid. Traditional, in-center hemodialysis is generally done three times a week for about four hours each session. Your doctor will prescribe how long your treatments will be, usually between 3 to 5 hours, but most common is 4 hours. Talk to your doctor about how long you should be on hemodialysis. Some people feel that dialysis lasts a long time; however, healthy kidneys work 24 hours a day, 7 days a week and dialysis must do the job in only 12 or so hours a week.

Alternative hemodialysis schedules include nocturnal and short daily. Normally, these treatments are performed by people who do home hemodialysis. With nocturnal hemodialysis, the patient has dialysis for about eight hours overnight while sleeping. This is a longer, gentler treatment so patients say they have fewer problems with cramping and the “washed out” feeling reported after traditional hemodialysis. More dialysis centers are beginning to offer in-center nocturnal hemodialysis based on reports of patients feeling better about their quality of life and having good lab results. Short daily hemodialysis is performed five or six times per week for about two to three hours each treatment. Talk to your doctor if you are interested in home hemodialysis (HHD) or in-center nocturnal dialysis. You may want to ask your social worker if addition treatments, such as the longer nocturnal hemodialysis and short daily hemodialysis will be covered through your insurance.

Advantages and disadvantages of hemodialysis

Hemodialysis is an effective treatment for those with end stage renal disease. However, hemodialysis alone will not provide a complete treatment for those with kidney failure. Diet and fluid restrictions need to be followed, and medicines may need to be taken to replace other functions of the kidneys, such as regulating blood pressure and stimulating production of red blood cells to prevent anemia.

For those who choose in-center hemodialysis, some of the benefits are that they will have their treatments performed in a dialysis center by trained professionals. They can spend their time in dialysis sleeping, reading, writing, watching television, listening to music or doing other quiet activities. There are four days a week when they will not have to go to dialysis. Some of the disadvantages are that they will have to travel to and from hemodialysis three times each week and it takes advanced notice to travel and arrange for dialysis in a visiting dialysis center. The diet restrictions include limiting foods that contain phosphorus, potassium and sodium and drinking a limited amount of fluid. Some people report a “washed out” feeling after hemodialysis and go home to take a nap. Those who perform nocturnal hemodialysis (in center or at home) report that this washed out feeling is not as common. Also, because nocturnal dialysis is performed during nonproductive sleeping hours, many people report they feel that their lives are more “normal” because they don’t have to take time out of their days for dialysis.

People who choose to perform hemodialysis at home say they enjoy the feeling of control they have over their lives. Instead of going to the dialysis center at a certain time, they can choose when to perform hemodialysis around their schedule.

Risks

Most people who require hemodialysis have a variety of health problems. Hemodialysis prolongs life for many people, but life expectancy for people who need it is still less than that of the general population.

While hemodialysis treatment can be efficient at replacing some of the kidney's lost functions, you may experience some of the related conditions listed below, although not everyone experiences all of these issues. Your dialysis team can help you deal with them.

• Low blood pressure (hypotension). A drop in blood pressure is a common side effect of hemodialysis, particularly if you have diabetes. Low blood pressure may be accompanied by shortness of breath, abdominal cramps, muscle cramps, nausea or vomiting.
• Muscle cramps. Although the cause is not clear, muscle cramps during hemodialysis are common. Sometimes the cramps can be eased by adjusting the hemodialysis prescription. Adjusting fluid and sodium intake between hemodialysis treatments also may help prevent symptoms during treatments.
• Itching. Many people who undergo hemodialysis have itchy skin, which is often worse during or just after the procedure.
• Sleep problems. People receiving hemodialysis often have trouble sleeping, sometimes because of breaks in breathing during sleep (sleep apnea) or because of aching, uncomfortable or restless legs.
• Anemia. Not having enough red blood cells in your blood (anemia) is a common complication of kidney failure and hemodialysis. Failing kidneys reduce production of a hormone called erythropoietin (uh-rith-roe-POI-uh-tin), which stimulates formation of red blood cells. Diet restrictions, poor absorption of iron, frequent blood tests, or removal of iron and vitamins by hemodialysis also can contribute to anemia.
• Bone diseases. If your damaged kidneys are no longer able to process vitamin D, which helps you absorb calcium, your bones may weaken. In addition, overproduction of parathyroid hormone — a common complication of kidney failure — can release calcium from your bones.
• High blood pressure (hypertension). If you consume too much salt or drink too much fluid, your high blood pressure is likely to get worse and lead to heart problems or strokes.
• Fluid overload. Since fluid is removed from your body during hemodialysis, drinking more fluids than recommended between hemodialysis treatments may cause life-threatening complications, such as heart failure or fluid accumulation in your lungs (pulmonary edema).
• Inflammation of the membrane surrounding the heart (pericarditis). Insufficient hemodialysis can lead to inflammation of the membrane surrounding your heart, which can interfere with your heart's ability to pump blood to the rest of your body.
• High potassium levels (hyperkalemia). Potassium is a mineral that is normally removed from your body by your kidneys. If you consume more potassium than recommended, your potassium level may become too high. In severe cases, too much potassium can cause your heart to stop.
• Access site complications. Potentially dangerous complications ― such as infection, narrowing or ballooning of the blood vessel wall (aneurysm), or blockage ― can impact the quality of your hemodialysis. Follow your dialysis team's instructions on how to check for changes in your access site that may indicate a problem.
• Amyloidosis. Dialysis-related amyloidosis develops when proteins in blood are deposited on joints and tendons, causing pain, stiffness and fluid in the joints. The condition is more common in people who have undergone hemodialysis for more than five years.
• Depression. Changes in mood are common in people with kidney failure. If you experience depression or anxiety after starting hemodialysis, talk with your health care team about effective treatment options.

How you prepare

Preparation for hemodialysis starts several weeks to months before your first procedure. To allow for easy access to your bloodstream, a surgeon will create a vascular access. The access provides a mechanism for a small amount of blood to be safely removed from your circulation and then returned to you in order for the hemodialysis process to work. The surgical access needs time to heal before you begin hemodialysis treatments.

There are three types of accesses:

• Arteriovenous (AV) fistula. A surgically created AV fistula is a connection between an artery and a vein, usually in the arm you use less often. This is the preferred type of access because of effectiveness and safety.
• AV graft. If your blood vessels are too small to form an AV fistula, the surgeon may instead create a path between an artery and a vein using a flexible, synthetic tube called a graft.
• Central venous catheter. If you need emergency hemodialysis, a plastic tube (catheter) may be inserted into a large vein in your neck or near your groin. The catheter is temporary.

You can receive hemodialysis in a dialysis center, at home or in a hospital. The frequency of treatment varies, depending on your situation:

• In-center hemodialysis. Many people get hemodialysis three times a week in sessions of three to five hours each.
• Daily hemodialysis. This involves more-frequent, but shorter sessions — usually performed at home six or seven days a week for about two to three hours each time.

Simpler hemodialysis machines have made home hemodialysis less cumbersome, so with special training and someone to help you, you may be able to do hemodialysis at home. You may even be able to do the procedure at night while you sleep.

There are dialysis centers located throughout the United States and in some other countries, so you can travel to many areas and still receive your hemodialysis on schedule. Your dialysis team can help you make appointments at other locations, or you can contact the dialysis center at your destination directly. Plan ahead to make sure space is available and proper arrangements can be made.

The procedure

During treatments, you sit or recline in a chair while your blood flows through the dialyzer ― a filter that acts as an artificial kidney to clean your blood. You can use the time to watch TV or a movie, read, nap, or perhaps talk to your "neighbors" at the center. If you receive hemodialysis at night, you can sleep during the procedure.

• Preparation. Your weight, blood pressure, pulse and temperature are checked. The skin covering your access site — the point where blood leaves and then re-enters your body during treatment — is cleansed.
• Starting. During hemodialysis, two needles are inserted into your arm through the access site and taped in place to remain secure. Each needle is attached to a flexible plastic tube that connects to a dialyzer. Through one tube, the dialyzer filters your blood a few ounces at a time, allowing wastes and extra fluids to pass from your blood into a cleansing fluid called dialysate. The filtered blood returns to your body through the second tube.
• Symptoms. You may experience nausea and abdominal cramps as excess fluid is pulled from your body — especially if you have hemodialysis only three times a week rather than more often. If you're uncomfortable during the procedure, ask your care team about minimizing side effects by such measures as adjusting the speed of your hemodialysis, your medication or your hemodialysis fluids.
• Monitoring. Because blood pressure and heart rate can fluctuate as excess fluid is drawn from your body, your blood pressure and heart rate will be checked several times during each treatment.
• Finishing. When hemodialysis is completed, the needles are removed from your access site and a pressure dressing is applied to prevent bleeding. Your weight may be recorded again. Then you're free to go about your usual activities until your next session.

Results

If you had sudden (acute) kidney injury, you may need hemodialysis only for a short time until your kidneys recover. If you had reduced kidney function before a sudden injury to your kidneys, the chances of full recovery back to independence from hemodialysis are lessened.

Although in-center, three-times-a-week hemodialysis is more common, some research suggests that home dialysis is linked to:

• Better quality of life
• Increased well-being
• Reduced symptoms and less cramping, headaches and shortness of breath
• Improved appetite, sleeping patterns, energy level and ability to concentrate

Your hemodialysis care team monitors your treatment to make sure you're getting the right amount of hemodialysis to remove enough wastes from your blood. Your weight and blood pressure are monitored very closely before, during and after your treatment. About once a month, you'll receive these tests:

• Blood tests to measure urea reduction ratio (URR) and total urea clearance (Kt/V) to see how well your hemodialysis is removing waste from your body
• Blood chemistry evaluation and assessment of blood counts
• Measurements of the flow of blood through your access during hemodialysis

Your care team may adjust your hemodialysis intensity and frequency based, in part, on test results.

Between treatments

Between hemodialysis treatments you can help achieve the best possible results from your hemodialysis by:

• Eating the right foods. Eating properly can improve your hemodialysis results and your overall health. While you're receiving hemodialysis, you'll need to carefully monitor your intake of fluids, protein, sodium, potassium and phosphorus. A dietitian can help you develop an individualized meal plan based on your weight, personal preferences, remaining kidney function and other medical conditions, such as diabetes or high blood pressure.
• Taking your medications as prescribed. Carefully follow the instructions from your health care team.
• Allowing your team to assist you by discussing your concerns. Your health care team can present options to you and help you deal with any concerns.