Dialysis
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Definition
Dialysis is a method of removing toxic substances (impurities or wastes) from the blood when the kidneys are unable to do so.
Alternative Names
Artificial kidneys; Hemodialysis; Peritoneal dialysis; Renal replacement therapy
How the test is performed
Dialysis can be performed using several different methods.
PERITONEAL DIALYSIS
Peritoneal dialysis filters waste using the peritoneal membrane inside the abdomen. The abdomen is filled with special solutions that help remove toxins. The solutions remain in the abdomen for a time and then are drained out. This form of dialysis can be performed at home, but must be done every day.
HEMODIALYSIS
Hemodialysis works by circulating the blood through special filters outside the body. The blood flows across a filter, along with solutions that help remove toxins.
Dialysis uses special ways of accessing the blood in the blood vessels. The access can be temporary or permanent.
Temporary access takes the form of dialysis catheters -- hollow tubes placed in large veins that can support acceptable blood flows. Most catheters are used in emergency situations for short periods of time. However, catheters called tunneled catheters can be used for prolonged periods of time, often weeks to months.
Permanent access is created by surgically joining an artery to a vein. This allows the vein to receive blood at high pressure, leading to a thickening of the vein's wall. This vein can handle repeated puncture and also provides excellent blood flow rates.
The connection between an artery and a vein can be made using blood vessels (an arteriovenous fistula, or AVF) or a synthetic bridge (arteriovenous graft, or AVG). Your health care provider may suggest an AVF, because it has lower infection rates and better long-term function than an AVG.
Blood is diverted from the access point in the body to a dialysis machine. Here, the blood flows counter-current to a special solution called the dialysate. The chemical imbalances and impurities of the blood are corrected and the blood is then returned to the body. Typically, most patients undergo hemodialysis for three sessions every week. Each session lasts 3 - 4 hours.
How to prepare for the test
When possible, patients should prepare for dialysis before dialysis is absolutely necessary.
It is important to stick to the diet and medicines prescribed by the dialysis staff and your kidney specialist (nephrologist).
The health care provider will make the following assessments before beginning the hemodialysis procedure:
- Blood pressure
- Breathing rate
- Chest assessment
- Examination of vein access
- Heart rate
- Temperature
- Weight
How the test will feel
Because dialysis takes several hours, it may be tedious. With children, it is especially important to have games, something to read, or other distractions.
Why the test is performed
The kidneys function as filters for the blood, removing waste products. They also:
Dialysis replaces some of the functions for kidneys that aren't working properly. It removes contaminants from the blood that could, and eventually would, lead to death if the kidney is not functioning.
Since dialysis is not a constant process, it cannot monitor body functions as do normal kidneys, but it can eliminate waste products and restore electrolyte and pH levels on an as-needed basis.
Dialysis is most often used for patients who have kidney failure, but it can also quickly remove drugs or poisons in acute situations. This technique can be lifesaving in people with acute or chronic kidney failure.
References
Tolkoff-Rubin N. Treatment of irreversible renal failure. In: Goldman L, Ausiello D, eds. Cecil Textbook of Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007: chap 133.
Mitch WE. Chronic kidney disease. In: Goldman L, Ausiello D, eds. Cecil Textbook of Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007: chap 131.
Review Date: 10/15/2008
Reviewed By: Parul Patel, MD, Private practice specializing in Nephrology, Kidney and Pancreas Transplantation, affiliated with California Pacific Medical Center, Department of Transplantation, San Francisco, CA. Review provided by VeriMed Healthcare Network. Also reviewed byDavid Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.
The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed physician should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. Copyright 2004 A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.
Alternative Names
Artificial kidneys; Hemodialysis; Peritoneal dialysis; Renal replacement therapy
What the risks are
The immediate risks include:
A small bubble of air in the blood that travels to a blood vessel in another part of the body (air embolism)
Bleeding from the access site
Cramps
Dialyzer reaction
Electrolyte imbalance
Infection
Irregular heartbeat or ischemia
- Nausea and vomiting
Long-term risks include:
Special considerations
Take the following precautions if you are using an AVF or AVG:
- Do not allow anyone to take a blood pressure reading on an arm with the access.
- Do not use creams or lotions over the access site.
- Do not wear tight clothing around the access site.
- Observe the access site after dialysis, watching for swelling, infection, or bleeding.
- Routinely check the access site for the "thrill," indicating that the AV site is still functioning. (If the thrill disappears, call your health care provider immediately.)
- When you sleep, avoid placing pressure on an arm with the access (if the graft or fistula clots, you may need a new one).
If you have an external access, take these additional precautions:
- Avoid physical activity that might dislodge the access, which could result in excessive bleeding and air entering the circulatory system. (If this happens, call 911 and get immediate medical attention.)
- Call your health care provider immediately if you have a fever or other sign of infection.
- If the color in the tubes changes and becomes a dark red, call your health care provider immediately. (The blood may be clotting.)
If you perform peritoneal dialysis at home:
Report any fever immediately.
Report any pain in your abdomen immediately.
Report any cloudiness or change in fluid color.
Do not miss or skip any dialysis sessions.
References
Tolkoff-Rubin N. Treatment of irreversible renal failure. In: Goldman L, Ausiello D, eds. Cecil Textbook of Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007: chap 133.
Mitch WE. Chronic kidney disease. In: Goldman L, Ausiello D, eds. Cecil Textbook of Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007: chap 131.
Review Date: 10/15/2008
Reviewed By: Parul Patel, MD, Private practice specializing in Nephrology, Kidney and Pancreas Transplantation, affiliated with California Pacific Medical Center, Department of Transplantation, San Francisco, CA. Review provided by VeriMed Healthcare Network. Also reviewed byDavid Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.
The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed physician should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. Copyright 2004 A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.
Alternative Names
Artificial kidneys; Hemodialysis; Peritoneal dialysis; Renal replacement therapy
References
Tolkoff-Rubin N. Treatment of irreversible renal failure. In: Goldman L, Ausiello D, eds. Cecil Textbook of Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007: chap 133.
Mitch WE. Chronic kidney disease. In: Goldman L, Ausiello D, eds. Cecil Textbook of Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007: chap 131.
Review Date: 10/15/2008
Reviewed By: Parul Patel, MD, Private practice specializing in Nephrology, Kidney and Pancreas Transplantation, affiliated with California Pacific Medical Center, Department of Transplantation, San Francisco, CA. Review provided by VeriMed Healthcare Network. Also reviewed byDavid Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.
The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed physician should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. Copyright 2004 A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.
Review Date: 10/15/2008
Reviewed By: Parul Patel, MD, Private practice specializing in Nephrology, Kidney and Pancreas Transplantation, affiliated with California Pacific Medical Center, Department of Transplantation, San Francisco, CA. Review provided by VeriMed Healthcare Network. Also reviewed byDavid Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.
The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed physician should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. Copyright 2004 A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.