What is dialysis?
Dialysis is a process that substitutes for kidney function when the normal operation of the kidneys is interrupted. In a healthy body, the kidneys serve to regulate fluid levels in the body and filter waste products. Dialysis performs these functions when the kidneys are unable to remove fluid or toxins from the body.
What are the different kinds of dialysis?
There are two major types of dialysis:
This is a procedure in which a dialysis machine is used to filter toxins, elctrolytes, and fluid from the blood. Hemodialysis is administered by health care professionals in a hospital or at an outpatient dialysis center, and it also can be done at home by the patient with proper training. Most hemodialysis patients get their treatments 3 days per week, but some patients choose to do more frequent treatments at home. With hemodialysis there is a risk of low blood pressure, blood clot, or infection, but with proper training these risks can be managed to reduce harm to the patient.
Peritoneal Dialysis (PD)
In this process, the body's own tissues are used to flush waste from the body through the use of sterile fluid instilled into the abdominal cavity. Peritoneal dialysis is self-administered by the patient through a catheter in the abdomen. Exchanges of fluid ("drain" and "fill") may be performed in any clean location in the home or during travel. It may also be possible for peritoneal dialysis to be administered during sleep via a fluid cycler machine. Unlike hemodialysis, peritoneal dialysis does not require needles, but PD exchanges typically do need to be performed multiple times every day or night.
What happens during hemodialysis?
During hemodialysis, blood is removed from a vein, typically in the patient's arm, circulated through a filtering machine, and returned to the body. Since veins tend to have weak blood flow, the doctor often connects one of the patient's arteries to the vein being used for dialysis. This increases blood flow to the vein. This artery-to vein connection can be created either through the use of synthetic material known as a graft, or through a direct surgical connection of one blood vessel to the other, which is known as a fistula.
In cases where creating a fistula or graft is not possible, or in emergency situations, a hemodialysis catheter may be inserted into a vein in the neck or upper leg in order to perform dialysis. These catheters are simliar to large IV's, with 2 ports visible outside the body. One port is used to pull blood from the body to the machine, and the other port is used to return blood to the patient from the machine. Unlike fistulas and grafts, catheters do not require needle sticks to access the patient's blood, but catheters are associated with higher risks of serious infection. Catheters also typically do not clean the blood as efficiently, so patients may require longer dialysis sessions.
What are the differences between grafts and fistulas?
Fistulas are created by a direct surgical connection from an artery to a vein. Arteries take blood from the heart to the rest of the body, and are high flow & high pressure vessels. Veins carry blood back to the heart, and are low flow & low pressure vessels. After the fistula is created, the vein thickens and strengthens in response to the higher blood flow from the artery, but this maturation process typically takes 2-3 months in order for the vein to be stong enough to withstand the needle sticks required to access the bloodstream and move blood to & from the dialysis machine.
Grafts, on the other hand, are synthetic material used to connect the artery to the vein if a direct connection cannot be achieved for a fistula. The graft material can be accessed with needle sticks immediately if needed because no maturation process is needed, but patients often wait until post-operative swelling has improved before using the graft for dialysis. Grafts usually work well, but fistulas generally are the preferred option because of better long term performance and lower infection risk.
What are the possible complications associated with dialysis?
While dialysis is generally a safe procedure, there are potential complications and risks associated with it. Infection can occur at the site of the dialysis access or in the bloodstream. Patients also may develop cramps or low blood pressure because fluid may need to be removed during the dialysis procedure. Other complications include irregular heart rate, blood loss, allergic reactions, and others. Hemodialysis and peritoneal dialysis can have different types of complications, so be sure to communicate with your healthcare providers to get more information.
Should special care be taken by a patient undergoing dialysis?
Yes. It is extremely important for the patient and health care professionals involved to avoid possible infection by hand washing, the use of surgical masks and antiseptic wipes, and inspection of supplies to ensure cleanliness. It also is common for patients to maintain a diet that is high in protein and low in potassium and phosphorous, and to monitor fluid intake carefully.
Is dialysis ever temporary?
Yes. There are circumstances in which dialysis is needed only for a short period of time until kidney function returns. Every case of kidney failure is different, so be sure to talk with your healthcare team to learn more about your specific situation.
Other than dialysis, is there any other effective treatment for kidney failure?
The only effective treatment for kidney failure other than hemodialysis or peritoneal dialysis is for the patient to receive a kidney transplant.
- National Kidney Foundation
- National Institutes of Health
- Centers for Disease Control and Prevention
- Eunice Kennedy Shriver National Institute of Child Health and Human Development
- U.S. Department of Health & Human Services
- U.S. National Library of Medicine
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