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Jai Ganesh

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Hemodialysis

Hemodialysis

Gist

Hemodialysis is a treatment to filter wastes and water from your blood, as your kidneys did when they were healthy. Hemodialysis helps control blood pressure and balance important minerals, such as potassium, sodium, and calcium, in your blood.

Summary

Hemodialysis, also spelled haemodialysis, or simply dialysis, is a process of purifying the blood of a person whose kidneys are not working normally. This type of dialysis achieves the extracorporeal removal of waste products such as creatinine and urea and free water from the blood when the kidneys are in a state of kidney failure. Hemodialysis is one of three renal replacement therapies (the other two being kidney transplant and peritoneal dialysis). An alternative method for extracorporeal separation of blood components such as plasma or cells is apheresis.

Hemodialysis can be an outpatient or inpatient therapy. Routine hemodialysis is conducted in a dialysis outpatient facility, either a purpose-built room in a hospital or a dedicated, stand-alone clinic. Less frequently hemodialysis is done at home. Dialysis treatments in a clinic are initiated and managed by specialized staff made up of nurses and technicians; dialysis treatments at home can be self-initiated and managed or done jointly with the assistance of a trained helper who is usually a family member.

Medical uses

Hemodialysis is the choice of renal replacement therapy for patients who need dialysis acutely, and for many patients as maintenance therapy. It provides excellent, rapid clearance of solutes.

A nephrologist (a medical kidney specialist) decides when hemodialysis is needed and the various parameters for a dialysis treatment. These include frequency (how many treatments per week), length of each treatment, and the blood and dialysis solution flow rates, as well as the size of the dialyzer. The composition of the dialysis solution is also sometimes adjusted in terms of its sodium, potassium, and bicarbonate levels. In general, the larger the body size of an individual, the more dialysis he/she will need. In North America and the UK, 3–4 hour treatments (sometimes up to 5 hours for larger patients) given 3 times a week are typical. Twice-a-week sessions are limited to patients who have a substantial residual kidney function. Four sessions per week are often prescribed for larger patients, as well as patients who have trouble with fluid overload. Finally, there is growing interest in short daily home hemodialysis, which is 1.5 – 4 hr sessions given 5–7 times per week, usually at home. There is also interest in nocturnal dialysis, which involves dialyzing a patient, usually at home, for 8–10 hours per night, 3–6 nights per week. Nocturnal in-center dialysis, 3–4 times per week, is also offered at a handful of dialysis units in the United States.

Details:

When is dialysis needed?

You need dialysis if your kidneys no longer remove enough wastes and fluid from your blood to keep you healthy. This usually happens when you have only 10 to 15 percent of your kidney function left. You may have symptoms such as nausea, vomiting, swelling and fatigue. However, even if you don't have these symptoms yet, you can still have a high level of wastes in your blood that may be toxic to your body. Your doctor is the best person to tell you when you should start dialysis.

How does hemodialysis work?

Hemodialysis is a procedure where a dialysis machine and a special filter called an artificial kidney, or a dialyzer, are used to clean your blood. To get your blood into the dialyzer, the doctor needs to make an access, or entrance, into your blood vessels. This is done with minor surgery, usually to your arm. For more information on hemodialysis access, click here.

How does the dialyzer clean my blood?

The dialyzer, or filter, has two parts, one for your blood and one for a washing fluid called dialysate. A thin membrane separates these two parts. Blood cells, protein and other important things remain in your blood because they are too big to pass through the membrane. Smaller waste products in the blood, such as urea, creatinine, potassium and extra fluid pass through the membrane and are washed away.

Where is hemodialysis done?

Hemodialysis can be done in a hospital, in a dialysis center that is not part of a hospital or at home. You and your doctor will decide which place is best, based on your medical condition, and your wishes.

How long will each hemodialysis treatment last?

In a dialysis center, hemodialysis is usually done 3 times per week for about 4 hours at a time. People who choose to do hemodialysis at home may do dialysis treatment more frequently, 4-7 times per week for shorter hours each time.

Your doctor will give you a prescription that tells you how much treatment you need. Studies have shown that getting the right amount of dialysis improves your overall health, keeps you out of the hospital and enables you to live longer. Your dialysis care team will monitor your treatment with monthly lab tests to ensure you are getting the right amount of dialysis. One of the measures your dialysis care team may use is called urea reduction ratio (URR). Another measure is called Kt/V (pronounced kay tee over vee). Ask your dialysis care team what measure they use and what your number is. To ensure that you are getting enough dialysis:

*your Kt/V should be at least 1.2 or
*your URR should be at least 65 percent.

Can I have hemodialysis at home?

Possibly. Many patients have their hemodialysis treatments at home. To learn more about home hemodialysis click here.

Do I need to eat a special diet?

Yes. Generally speaking, patients on dialysis are advised to increase their protein intake and limit the amount of potassium, phosphorus, sodium, and fluid in their diet. Patients with diabetes or other health conditions may have additional diet restrictions. It's important to talk with you dietitian about your individual diet needs.

Your dialysis care team will monitor your treatment with monthly lab tests to ensure you get the right amount of dialysis and that you are meeting your dietary goals.

Can dialysis cure my kidney disease?

In some cases of sudden or acute kidney failure, dialysis may only be needed for a short time until the kidneys get better. However, when chronic kidney disease progresses to kidney failure over time, your kidneys do not get better and you will need dialysis for the rest of your life unless you are able to receive a kidney transplant.

Will I be uncomfortable on hemodialysis?

When you begin hemodialysis, the needles put in your fistula or graft may be uncomfortable. Most patients get used to this in time. Your dialysis care team will make sure you are as comfortable as possible during your treatment. Symptoms like cramps, headaches, nausea or dizziness are not common, but if you do have any of them, ask your dialysis care team if any of the following steps could help you:

*Slow down your fluid removal, which could increase your dialysis time.
*Increase the amount of sodium in your dialysate.
*Check your high blood pressure medications.
*Adjust your dry weight, or target weight.
*Cool the dialysate a little.
*Use a special medication to help prevent low blood pressure during dialysis.

You can help yourself by following your diet and fluid allowances. The need to remove too much fluid during dialysis is one of the things that may make you feel uncomfortable during your treatment.

How will I pay for my dialysis?

Dialysis is expensive. However, the federal government's Medicare program pays 80 percent of all dialysis costs for most patients. Private health insurance or state medical aid may also help with the costs.

I have heard I might have to reuse my dialyzer each treatment. Is this safe?

Before you reuse your dialyzer, your dialysis center cleans it according to careful guidelines. If done properly, reuse is generally safe. Before each treatment, your dialyzer must be tested to make sure it is still working well. If your dialyzer no longer works well, it should be discarded and you should be given a new one. Ask your dialysis care team if they have tested your dialyzer and if it still works well.

If you do not wish to reuse your dialyzer, your center may be willing to provide you with a new dialyzer for each treatment. Ask about the center's policy on reuse.

Can dialysis patients travel?

Yes. Dialysis centers are located in every part of the United States and in many foreign countries.

Before you travel, you must make an appointment for dialysis treatments at another center. The staff at your center may be able to help you arrange this appointment.

Can dialysis patients continue to work?

Yes. Many dialysis patients continue to work or return to work after they have gotten used to dialysis. If your job has a lot of physical labor (heavy lifting, digging, etc.), you may need to change your duties.

Additional Information

Dialysis, also called hemodialysis, renal dialysis, or kidney dialysis, in medicine, is the process of removing blood from a patient whose kidney functioning is faulty, purifying that blood by dialysis, and returning it to the patient’s bloodstream. The artificial kidney, or hemodialyzer, is a machine that provides a means for removing certain undesirable substances from the blood or of adding needed components to it. By these processes the apparatus can control the acid–base balance of the blood and its content of water and dissolved materials. Another known function of the natural kidney—secretion of hormones that influence the blood pressure—cannot be duplicated. Modern dialyzers rely on two physicochemical principles, dialysis and ultrafiltration.

In dialysis two liquids separated by a porous membrane exchange those components that exist as particles small enough to diffuse through the pores. When the blood is brought into contact with one side of such a membrane, dissolved substances (including urea and inorganic salts) pass through into a sterile solution placed on the other side of the membrane. The red and white cells, platelets, and proteins cannot penetrate the membrane because the particles are too large. To prevent or limit the loss of diffusible substances required by the body, such as sugars, amino acids, and necessary amounts of salts, those compounds are added to the sterile solution; thus their diffusion from the blood is offset by equal movement in the opposite direction. The lack of diffusible materials in the blood can be corrected by incorporating them in the solution, from which they enter the circulation.

Although water passes easily through the membrane, it is not removed by dialysis because its concentration in the blood is lower than in the solution; indeed, water tends to pass from the solution into the blood. The dilution of the blood that would result from this process is prevented by ultrafiltration, by which some of the water, along with some dissolved materials, is forced through the membrane by maintaining the blood at a higher pressure than the solution.

The membranes first used in dialysis were obtained from animals or prepared from collodion; cellophane has been found to be more suitable, and tubes or sheets of it are used in many dialyzers. In the late 1960s hollow filaments of cellulosic or synthetic materials were introduced for dialysis; bundles of such filaments provide a large membrane surface in a small volume, a combination advantageous in devising compact dialyzers.

Dialysis—which was first used to treat human patients in 1945—replaces or supplements the action of the kidneys in a person suffering from acute or chronic renal failure or from poisoning by diffusible substances, such as aspirin, bromides, or barbiturates. Blood is diverted from an artery, usually one in the wrist, into the dialyzer, where it flows—either by its own impetus or with the aid of a mechanical pump—along one surface of the membrane. Finally the blood passes through a trap that removes clots and bubbles and returns to a vein in the patient’s forearm. In persons with chronic kidney failure, who require frequent dialysis, repeated surgical access to the blood vessels used in the treatments is obviated by provision of an external plastic shunt between them.

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