What is hemodialysis?

Hemodialysis is a treatment to filter toxins and water from the blood, like the kidneys did when they were healthy. Helps control blood pressure and balance important blood minerals such as potassium, sodium, and calcium.

Hemodialysis is not a cure for kidney failure, but it can help the patient feel better and live longer.




During hemodialysis, blood is pumped through a filter known as a dialyzer, out of the body. The dialyzer is also known as an "artificial kidney."

What Happens During Hemodialysis?

At the beginning of a hemodialysis treatment, a nurse or dialysis technician will place two needles in the patient's arm. The patient may prefer to insert their own needles after being trained by the healthcare team. You can use a skin numbing cream or spray if the needles bother you at the point of entry. Each needle is attached to a soft tube connected to the dialysis machine.

During hemodialysis, blood is pumped through a filter known as a dialyzer.

The dialysis machine pumps the blood through the filter and returns it to the body. During the process, the dialysis machine checks your blood pressure and controls how quickly:

  • blood flows through the filter

  • fluid is removed from the body

What happens to the patient's blood while it is in the filter?

Blood passes through one end of the filter and enters many very thin hollow fibers. As the blood passes through the hollow fibers, the dialysis solution passes in the opposite direction on the outside of the fibers. Toxins from the blood pass into the dialysis solution. The filtered blood remains in the hollow fibers and returns to the body.


In the filter, blood flows into hollow fibers that filter out toxins and excess salt and water.

The nephrologist, a doctor who specializes in kidney problems, will prescribe a dialysis solution to meet your needs. The dialysis solution contains water and chemicals that are added to safely remove toxins, excess salt, and fluid from the blood. The doctor can adjust the balance of the chemicals in the solution if:

  • blood tests show that the blood has too much or too little of certain minerals, such as potassium or calcium

  • the patient has problems such as low blood pressure or muscle cramps during dialysis



Can the dialyzer do everything the patient's kidneys ever did?

No. Hemodialysis can replace some, but not all, kidney function. Dialysis will help improve your energy level, and changes you make to your diet can help you feel better. Limiting the amount of water and other fluids that the patient drinks and absorbs through food can help prevent too much fluid from building up in the body between treatments. Medications also help maintain health while the patient is on dialysis.


Where can the patient receive hemodialysis treatment?

You can receive treatment in a dialysis center or at home, however, due to biosafety in care, it is preferable to go to a center.

Most people go to a dialysis center for treatment. At the dialysis center, healthcare professionals set up the dialysis machine and help the patient connect. A team of healthcare workers will be available to help you. The patient will continue to attend a consultation with the doctor. Other team members may include nurses, health care technicians, a dietitian, and a social worker.

The patient will have a reserved time for the treatments, generally three times a week: Monday, Wednesday and Friday; or Tuesday, Thursday and Saturday. Each dialysis session lasts about 4 hours. When choosing a time for dialysis, think about your job, babysitting, or other tasks.

A schedule can be chosen to suit the patient's lifestyle. You can use:

Healthy kidneys work 24 hours a day, 7 days a week. Receiving more hemodialysis is closer to feeling healthy kidneys and reduces the chance of problems that are common with a standard hemodialysis program, such as:

  • painful muscle cramps from drawing too much fluid too quickly

  • high blood pressure, which can cause a headache or, in rare cases, a stroke

  • low blood pressure, which can make the patient feel weak or sick to the stomach, or more prone to falling

  • high levels of phosphate, which can weaken bones and cause itchy skin

Better life quality
After each treatment, standard hemodialysis can make you feel tired or exhausted for several hours.


Strict limits on fluid intake, phosphorus, sodium, and potassium.

Fewer limits on fluids or diet, depending on the amount of hemodialysis and lab tests.

Degree of freedom

Less freedom on treatment days. You may feel exhausted and tired for hours after each treatment.

More freedom because the patient sets the treatment program to meet the total amount prescribed. Work and travel are so much easier.

Amount of work

Center staff members do the homework for hemodialysis. They can teach the patient to do some tasks.

The patient and their companion must set up, operate and clean the machine; check vital signs; keep a record of the treatments and send the forms; order supplies.


How does the patient prepare for hemodialysis?

Dialysis is a complex treatment that takes time to understand. Because most people don't feel sick until shortly before starting dialysis, they will probably still feel fine when their doctor first talks to them about the need to prepare for dialysis. It's not about starting dialysis before it's needed, but preparation takes time.


Caring for the blood vessels in the arms

It is important to protect the veins in your arm before starting dialysis. If the patient has kidney disease, you should remind healthcare providers to draw blood and insert IV lines only into the veins below the wrist; for example, you should ask them to use a vein on the back of their hand. If a vein in your arm has been damaged by an IV or repeated blood draws, that vein may not be able to be used for dialysis.


Surgery for vascular access

An important step before starting hemodialysis treatment is to do a small surgery to create a vascular access. Vascular access will be the lifeline through which the patient will be connected to the dialyzer. Dialysis moves the blood through the filter at high speed. The blood flow is very strong. The machine draws and returns nearly a pint of blood to the body every minute. The access will be where the needles will be inserted to allow blood to flow back into the body at high speed during dialysis.

There are three types of vascular access:

  • an arteriovenous (AV) fistula

  • an AV graft

  • a catheter


The surgeon connects an artery to a vein to create an AV fistula.

Arteriovenous fistula
The best type of long-term access is through an arteriovenous (AV) fistula. The surgeon connects an artery to a vein, usually in the arm, to create an AV fistula. An artery is a blood vessel that carries blood from the heart. A vein is a blood vessel that returns blood to the heart. When the surgeon connects an artery to a vein, the vein widens and thickens, making it easier to place the needles for dialysis. The AV fistula also has a large diameter that allows blood to flow quickly back into the body. The goal is to allow high blood flow so that the greatest amount of blood can pass through the dialyzer.

An AV fistula is a blood vessel that the surgeon widens and strengthens so that it can support the needles that allow blood to flow back from a dialysis machine.

AV fistula is considered the best option because:

  • provides the greatest blood flow for dialysis

  • less likely to become infected or clot

  • lasts longer

Most people can go home after outpatient surgery. The patient will receive local anesthesia NIH external link to numb the area where the vascular surgeon creates the AV fistula. Depending on the patient's situation, you may receive general anesthesia and not be awake during the procedure.


AV graft
If the patient has problems with the veins that prevent an AV fistula, an AV graft may be needed. To create an AV graft, the surgeon uses an artificial tube to connect an artery to a vein. An AV graft can be used for dialysis shortly after surgery. However, the patient is more likely to have problems with infections and blood clots. Frequent blood clots can block blood flow through the graft and make dialysis difficult or impossible.


An AV graft uses a synthetic tube to connect an artery and vein to facilitate hemodialysis.

Temporary access catheter
If the patient's kidney disease has progressed rapidly or if a vascular access was not placed before he needed dialysis, he may need a venous catheter, which is a small, soft tube that is inserted into a vein in the neck, chest or leg near the groin, as a temporary access. The nephrologist or interventional radiologist, who is a doctor who uses medical imaging equipment to do surgery, places the venous catheter while the patient is in the hospital or at an outpatient clinic. You will be given local anesthesia and medications to keep you calm and relaxed during the procedure.


What changes will the patient have to make when hemodialysis begins?

You must adjust your life to make dialysis treatment sessions part of your routine. If you are on dialysis at the center, you may need to rest after each treatment. It can be difficult to adjust to the effects of kidney failure and the time you spend on dialysis. You may need to make changes in your job or family life, giving up some activities and responsibilities. Accepting these changes can be difficult for the patient and their family. A mental health counselor or social worker can answer questions and help the patient cope with the illness.

The patient will have to change what he eats and drinks. Your healthcare team can adjust the medications you take.

Take care of access

Access is the life line, therefore you must protect it. You should wash the area around the access with soap and warm water every day and check the area for signs of infection, such as warmth or redness. When blood flows through the access and the access is working well, the patient may feel a vibration over the area. You should inform the dialysis center if you cannot feel the vibration.

Change what you eat and drink

If the patient is on hemodialysis, you may need to limit:

  • sodium in food and drink

  • foods rich in phosphorus

  • the amount of liquid you drink, including the liquid found in food. Fluid builds up in the body between hemodialysis treatments.

You may also need:

  • adding protein to the diet because hemodialysis removes protein

  • choosing foods with the right amount of potassium

  • taking vitamins made for people with kidney failure

  • find healthy ways to add calories to your diet because you may feel inappetent


A dietitian should be consulted to develop a proper meal plan.

Eating the right foods can help the patient feel better during hemodialysis . You should consult with the dietitian at the dialysis center to find a suitable meal plan.

How does the patient know if hemodialysis is working?

The patient will know if the hemodialysis treatments are working depending on how they feel. Your energy level may increase and you may have an increased appetite. Hemodialysis reduces salt and fluid build-up, so you should have less shortness of breath and less swelling.


To get the most out of hemodialysis treatment, the patient must maintain their ideal "dry weight". The ideal dry weight is the weight when there is no excess fluid in the body. If the patient is careful about sodium in the diet and hemodialysis is working, he should be able to reach his ideal dry weight at the end of each hemodialysis treatment. When hemodialysis treatments work and the patient maintains his ideal dry weight, blood pressure should be controlled.


The patient must maintain their ideal dry weight.

Also, blood tests can show how well hemodialysis treatments are working. Once a month, whether the patient is on hemodialysis at home or at the dialysis center, they will have a blood test at the dialysis center.

What are the possible problems with hemodialysis?

You could have a problem with your vascular access, which is the most common reason people on hemodialysis need to go to the hospital. Any type of vascular access can:

  • become infected

  • have poor blood flow or obstruction due to a clot or scar

These problems can prevent treatments from working. Additional procedures may be required to replace or repair the access for it to function properly.

Some sudden changes in the water and chemical balance of the body during treatment can cause other problems such as:

  • muscle cramps

  • a sudden drop in blood pressure, called hypotension. Hypotension can cause the patient to feel weak, dizzy, or have an upset stomach.

Your doctor can change your dialysis solution to help prevent these problems. Longer and more frequent home hemodialysis treatments are less likely to cause muscle cramps or rapid changes in blood pressure than standard in-center dialysis.

Blood can be lost if the needle comes out of the access or the tube comes out of the dialyzer. To prevent blood loss, dialysis machines have a blood leak detector that triggers an alarm. If this problem occurs in the clinic, a nurse or technician will be available to take action. If dialysis is being done at home, the training will prepare the patient and their companion to solve the problem.

It may take a few months to adjust to hemodialysis. The patient should always report problems to their healthcare team, who can often treat side effects quickly and easily. Many side effects can be avoided by following the meal plan developed with the dietitian, limiting fluid intake, and taking medications as directed.

What happens if the patient has been on dialysis and decides to stop it?

If the patient has been on dialysis and wishes to stop it, they will continue to receive supportive care. The dialysis social worker can help you develop an end-of-life care plan before stopping dialysis.