- Dialysis definition and facts
- What is dialysis?
- When do patients require dialysis?
- What are the types of dialysis? How do they work?
- Where do I get dialysis treatment? How long does it take? How often do I have to get it?
- What are the advantages of the different types of dialysis?
- What is the life expectancy for someone on dialysis?
- How can patients learn more about dialysis?
Dialysis definition and facts
- Kidney dialysis is a procedure that is a substitute for many of the normal functions of the kidneys.
- Dialysis allows people with kidney failure (renal failure) a chance to live productive lives.
- When kidney function decreases to a critical level or complications arise, a person may need to start dialysis.
- There are two main types of dialysis, hemodialysis and peritoneal dialysis.
- Hemodialysis uses a machine and a filter to remove waste products and water from the blood.
- Peritoneal dialysis uses a fluid (dialysate) that is placed into the patient's abdominal cavity to remove waste products and fluid from the body.
- Each type of dialysis has advantages and disadvantages.
- People often can choose which type of long term dialysis that best matches their needs.
- Dialysis gives some people an extended life, and in others, it provides additional time to locate an appropriate donor kidney for a kidney transplant (renal transplant).
What is dialysis?
The kidneys are responsible for filtering waste products from the blood. Dialysis is a procedure that is a substitute for many of the normal functions of the kidneys. The kidneys are two organs located on either side in the back of the abdominal cavity. Dialysis can allow individuals to live productive and useful lives, even though their kidneys no longer work adequately. Statistics from 2015, U.S. Renal Data System Annual Data Report (USRDS), showed approximately 468,000 patients were receiving dialysis in the United States. More than an additional 193,000 patients had a functioning kidney transplant for end stage renal disease.
Dialysis helps the body by performing the functions of failed kidneys. The kidney has many roles. An essential job of the kidney is to regulate the body's fluid balance. It does this by adjusting the amount of urine that is excreted on a daily basis. On hot days, the body sweats more. Thus, less water needs to be excreted through the kidneys. On cold days, the body sweats less. Thus, urine output needs to be greater in order to maintain the proper balance within the body. It is the kidney's job to regulate fluid balance by adjusting urine output.
Another major duty of the kidney is to remove the waste products that the body produces throughout the day. As the body functions, cells use energy. The operation of the cells produces waste products that must be removed from the body. When these waste products are not removed adequately, they build up in the body. An elevation of waste products, as measured in the blood, is called "azotemia." When waste products accumulate they cause a sick feeling throughout the body called "uremia," which is due to urea and other nitrogenous waste compounds.
When do patients require dialysis?
When the kidneys fail to filter the blood effectively, and fluid and waste products build up in the body to a critical level a person may need to start dialysis. The two main causes of kidney failure and need for dialysis treatment are diabetes and high blood pressure.
When a person’s levels of waste products in their body become so high they start to become sick from them, he or she may need dialysis. The level of the waste products usually builds up slowly. Doctors that specialize in diseases and conditions of the kidneys are called nephrologists. To help nephrologists decide when dialysis is necessary for a patient, he she will order tests that measure several blood chemical levels in the patient’s body. The two major blood chemical levels that are measured are the "creatinine level" and the "blood urea nitrogen" (BUN) level. As these two levels rise, they are indicators of the decreasing ability of the kidneys to cleanse the body of waste products.
Doctors use a urine test, the "creatinine clearance," to measure the level of kidney function. The patient saves urine in a special container for one full day. The waste products in the urine and in the blood are estimated by measuring the creatinine. By comparing the blood and urine level of this substance, the doctor has an accurate idea of how well the kidneys are working. This result is called the creatinine clearance. Usually, when the creatinine clearance falls to 1 below 10 cc/minute, the patient needs dialysis.
The doctor also uses other indicators of the patient's status to decide about the need for dialysis. If the patient is experiencing a major inability to rid the body of excess water, or is complaining of problems with the heart, lungs, or stomach, or difficulties with taste or sensation in their legs, dialysis may be indicated even though the creatinine clearance has not fallen to the 10 cc/minute level.
What are the types of dialysis? How do they work?
There are two main types of dialysis, hemodialysis and peritoneal dialysis.
How hemodialysis works
Hemodialysis uses an external machine and a special type of filter to remove excess waste products and water from the blood.
During hemodialysis, blood passes from the patient's body to the dialysis machine through sterile tubing and into a filter, called a dialysis membrane. For this procedure, the patient has a specialized vascular tube placed between an artery and a vein in the arm or leg (called a gortex graft). Sometimes, a direct connection is made between an artery and a vein in the arm. This procedure is called a Cimino fistula. Needles are then placed in the graft or fistula, and blood passes to the dialysis machine, through the filter, and back to the patient. If the patient requires dialysis before a graft or a fistula is placed, a large diameter catheter (hemodialysis catheter) is placed directly into a large vein in the neck or leg in order to perform dialysis. In the dialysis machine, a solution on the other side of the filter receives the waste products from the patient.
How peritoneal dialysis works
Peritoneal dialysis uses a fluid that is placed into the patient's abdominal cavity through a plastic tube (peritoneal dialysis catheter) to remove excess waste products and fluid from the body.
Peritoneal dialysis uses the patients own body tissues inside of the belly (abdominal cavity) to act as the filter. The abdominal cavity is lined with a special membrane called the peritoneal membrane. A plastic tube called a peritoneal dialysis catheter is placed through the abdominal wall into the abdominal cavity. A special fluid called dialysate is then flushed into the abdominal cavity and washes around the intestines. The peritoneal membrane acts as a filter between this fluid and the blood stream. By using different types of solutions, waste products and excess water can be removed from the body through this process.
Where do I get dialysis treatment? How long does it take? How often do I have to get it?
Treatment for hemodialysis usually takes place in a hemodialysis unit. This is a special building that is equipped with machines that perform the dialysis treatment. The dialysis unit is also the place where patients can receive dietary counseling and help with social needs.
Patients generally go to the dialysis unit three times a week for treatment. For example, the schedule is either Monday, Wednesday, and Friday or Tuesday, Thursday, and Saturday. Before treatment, patients weigh themselves so that excess fluid accumulated since the last dialysis session can be measured. Patients then go to assigned chairs that are like lounge chairs. The area of the graft or fistula (the connection between the artery and vein), is cleaned thoroughly. Two needles are then inserted into the graft or fistula. One takes the blood to the machine where it is cleaned. The other needle allows blood that is returning to the patient to go back into the patient's body.
Treatments last from 2 ½ to 4 ½ hours. During this time, the dialysis staff checks the patient's blood pressure frequently and adjusts the dialysis machine to ensure that the proper amount of fluid is being removed from the patients body. Patients can read, watch television, sleep, or do other work during treatment. On occasion, patients who are very motivated may be able to perform dialysis themselves at home in a process called home hemodialysis.
Peritoneal dialysis requires the patient to play a more active role in their dialysis treatment. Of primary importance is the patient's responsibility for maintaining a clean surface on the abdomen and catheter, where treatment is administered, in order to prevent infection.
During this process, the patient weighs herself/himself to determine the strength of fluid to be used. The patient then puts on a mask and cleans the peritoneal catheter site. Fluid that has been allowed to stay in the peritoneal cavity while the peritoneal membrane filters waste into the fluid. The fluid and waste are is then drained back into the plastic bag that originally contained the fluid. The patient then disconnects this bag containing waste in the fluid and connects a new bag of solution that is allowed to drain into the peritoneal cavity. Once the fluid is in the body, the new bag is rolled up and placed in the patient's underwear until the next treatment. This procedure usually takes 30 minutes to accomplish and must be done four to five times a day.
As an alternative to this treatment, some patients on peritoneal dialysis use a machine called a "cycler." This cycler is used every night. Five to six bags of dialysis fluid are used on the cycler and the machine automatically changes the fluid while the patient sleeps.
- FDA Panel Backs RSV Vaccine for Infants, Some Toddlers
- Seniors: Stay Social, Active for 'Optimal Aging,' Study Shows
- Diabetes Med Metformin Might Help Prevent Long COVID
- Disability a Growing Concern for U.S. Cancer Survivors
- Smoke From Wildfires Is Especially Tough If You Have Asthma. Here’s How to Protect Yourself
- More Health News »
What are the advantages of the different types of dialysis?
Each of the two types of dialysis, hemodialysis and peritoneal dialysis, has advantages and disadvantages. It is up to the patient and their kidney doctor to decide which of these procedures is best by considering her/his life style, other medical conditions, support systems, and how much responsibility and participation in the treatment program he/she desires. The patient must realize that because of their specific medical condition, they may not be a candidate for one or the other type of dialysis. Each patient must view the two types of dialysis procedures from her/his own perspective.
Regardless of which type of dialysis is chosen, patients have certain responsibilities such as following a diet program, watching their fluid intake, taking special vitamins, and other medicines to control blood pressure and calcium and phosphorus balance.
For many patients, the major advantage of hemodialysis is minimal participation in the treatment. However, patients are required to adhere to a specific schedule and travel to the dialysis unit three times a week. Hemodialysis also requires stricter diet control and fluid control than peritoneal dialysis.
For those patients preferring more independence, peritoneal dialysis allows for more flexible scheduling and can be performed at home. The patient must undergo a certain amount of dialysis each day, but can alter the exact timing of the dialysis procedure.
A major problem with peritoneal dialysis is infection. The patient has a plastic tube that goes from the peritoneal cavity to the outside of the body and this is a potential site for the entry of bacteria into the body. Great emphasis is placed on cleanliness and technique during the training sessions.
What is the life expectancy for someone on dialysis?
The expected lifespan of a patient receiving dialysis in the United States Renal Data System (USRDS) report was approximately 8 years for dialysis patients 40 to 44 years of age and approximately 4.5 years for those 60 to 64 years of age. This is a highly variable range that is dependent on many factors such as:
- age of patient,
- quality of dialysis treatment,
- other medical issues in the patient (comorbidities),
- quality of pre-dialysis treatment,
- control of potassium levels, and
- overall compliance of the patient.
Some patients do dialysis as a bridge (time to locate an appropriate donor kidney) to getting a kidney transplant (renal transplant). If a patient is successful in getting a transplant and is able to stop dialysis, their survival prognosis increases greatly.
How can patients learn more about dialysis?
As a patient approaches dialysis, there are numerous sources of information. The doctor often has access to training videos that explain the dialysis techniques and their respective advantages and disadvantages.
Throughout the country are regional units of the National Kidney Foundation. These can be contacted, either through your physician or by contacting local dialysis units.
The National Kidney Foundation
30 East 33rd St.
New York, NY 10016
The American Association of Kidney Patients is an active association of patients and families involved with dialysis and a very good source of information.
American Association of Kidney Patients
3505 E. Frontage Rd., Ste. 315
Tampa, FL 33607
Health Solutions From Our Sponsors
Mailloux, MD, MD. et al. "Patient survival and maintenance dialysis." UpToDate. Updated: Oct 13, 2017.
National Kidney Foundation. "End Stage Renal Disease in the United States." Updated: January 2016.
Tattersall, James et al. "When to start dialysis: updated guidance following publication of the Initiating Dialysis Early and Late (IDEAL) study." Published: May 2011. Nephrology Dialysis Transplantation, Volume 26, Issue 7, 1 July 2011, Pages 2082–2086.
Top Dialysis Related Articles
Kidney AngiomyolipomaAngiomyolipomas are noncancerous tumors that are typically found in the kidney, but may occur in the liver, ovary, colon, or Fallopian tube. Symptoms and signs include shock, chronic kidney disease, anemia, vomiting, nausea, and back or flank pain. Treatment may involve taking medication and embolization of the tumor.
Ankylosing SpondylitisAnkylosing spondylitis is a type of arthritis that causes chronic inflammation of the spine. The tendency to develop ankylosing spondylitis is genetically inherited. Treatment incorporates medications, physical therapy, and exercise.
Common Medical Abbreviations & Terms
Doctors, pharmacists, and other health-care professionals use abbreviations, acronyms, and other terminology for instructions and information in regard to a patient's health condition, prescription drugs they are to take, or medical procedures that have been ordered. There is no approved this list of common medical abbreviations, acronyms, and terminology used by doctors and other health- care professionals. You can use this list of medical abbreviations and acronyms written by our doctors the next time you can't understand what is on your prescription package, blood test results, or medical procedure orders. Examples include:
- ANED: Alive no evidence of disease. The patient arrived in the ER alive with no evidence of disease.
- ARF: Acute renal (kidney) failure
- cap: Capsule.
- CPAP: Continuous positive airway pressure. A treatment for sleep apnea.
- DJD: Degenerative joint disease. Another term for osteoarthritis.
- DM: Diabetes mellitus. Type 1 and type 2 diabetes
- HA: Headache
- IBD: Inflammatory bowel disease. A name for two disorders of the gastrointestinal (BI) tract, Crohn's disease and ulcerative colitis
- JT: Joint
- N/V: Nausea or vomiting.
- p.o.: By mouth. From the Latin terminology per os.
- q.i.d.: Four times daily. As in taking a medicine four times daily.
- RA: Rheumatoid arthritis
- SOB: Shortness of breath.
- T: Temperature. Temperature is recorded as part of the physical examination. It is one of the "vital signs."
Creatinine Blood TestCreatinine is a chemical waste molecule that is generated from muscle metabolism. Creatinine is produced from creatine, a molecule of major importance for energy production in muscles. Creatinine has been found to be a fairly reliable indicator of kidney function. As the kidneys become impaired the creatinine level in the blood will rise. Normal levels of creatinine in the blood vary from gender and age of the individual.
ElectrolytesElectrolytes are substances that become ions in solution and acquire the capacity to conduct electricity. The balance of the electrolytes in our bodies is essential for normal function of our cells and our organs. Common electrolytes include sodium, potassium, chloride, and bicarbonate. The functions and normal range values for these electrolytes are important, and if an electrolyte is at an extreme low or high, it can be fatal.
EncephalopathyEncephalopathy refers to brain disease, damage, or malfunction. Learn about what causes encephalopathy as well as types, symptoms, stages, and treatment.
Kidney Disease QuizKidney disease is common. Take this kidney disease quiz to test your knowledge and learn the symptoms, causes and types of kidney disease and what foods to eat and avoid!
Kidney (Renal) Failure
Kidney failure can occur from an acute event or a chronic condition or disease. Prerenal kidney failure is caused by blood loss, dehydration, or medication. Some of the renal causes of kidney failure include sepsis, medications, rhabdomyolysis, multiple myeloma, and acute glomerulonephritis.
Post renal causes of kidney failure include bladder obstruction, prostate problems, tumors, or kidney stones.Treatment options included diet, medications, or dialysis.
Kidneys PictureThe kidneys are a pair of organs located in the back of the abdomen. See a picture of the Kidneys and learn more about the health topic.
Sepsis (Blood Poisoning)Sepsis (blood poisoning) is a potentially deadly infection with signs and symptoms that include elevated heart rate, low or high temperature, rapid breathing and/or a white blood cell count that is too high or too low and has more than 10% band cells. Most cases of sepsis are caused by bacterial infections, and some cases are caused by fungal infections. Treatment requires hospitalization, IV antibiotics, and therapy to treat any organ dysfunction.
Lupus (Systemic Lupus Erythematosus or SLE)Systemic lupus erythematosus is a condition characterized by chronic inflammation of body tissues caused by autoimmune disease. Lupus can cause disease of the skin, heart, lungs, kidneys, joints, and nervous system. When only the skin is involved, the condition is called discoid lupus. When internal organs are involved, the condition is called systemic lupus erythematosus (SLE).
Thrombocytopenia (Low Platelet Count)
Thrombocytopenia (low platelet count) refers to a decreased number of platelets in the blood. Symptoms of thrombocytopenia include:
- Increased bruising
- Spontaneous bleeding
- Small, purple spots under the skin called purpura
There are many causes of thrombocytopenia such as decreased platelet production (viral infections for example rubella, mumps, chickenpox, hepatitis C, and HIV); increased platelet destruction or consumption (for example sulfonamide antibiotics, heparin, blood transfusions, and lupus); or increased splenic sequestration (enlarged spleen due to conditions, for example, liver disease, blood cancers, and more). Treatment of thrombocytopenia depends on the cause.