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Renal Veins & Arteries
Anal Sphincter
Ureters, Bladder, Urethra
Kidney Failure
Treatment - Dialysis
Diagrams 2
Treatment - Dialysis


Definition: When the kidneys are not functioning properly, dialysis acts as an artificial kidney, and can be used to remove wastes from the blood. Dialysis can also restore electrolyte and pH levels in the body. Dialysis is used most often in cases of kidney failure, but can also be used when drugs or poisons need to be removed rapidly from the blood. Dialysis saves lives of people with kidney failure.

How Dialysis is performed: There are two main methods of dialysis:

Peritoneal dialysis Peritonial dialysis uses a semi permeable membrane found in the abdomen as a filter. This is called the peritoneal membrane. Solutions are infused into this membrane to remove impurities from the blood. These solutions stay in the abdomen until they are drained out. Peritoneal dialysis is often the prefered method of dialysis, because it can be done by the patient in their own home. However, it needs to be done daily. This form of dialysis allows more freedom, as the patient does not have to go to a dialysis clinic for hours at a time, three times a week. However, this treatment can cause an infection in the peritoneal membrane, and the process is not as successful on obese patients.

Hemodialysis In hemodialysis the patients blood is put through special filters. It frees the blood of impurities by having the blood flow with special solutions through a dialyzer or filter. For the process to be effective the patient’s blood has to be flowing at 400-500 mL/minute. The patient’s circulatory system needs to be accessed, and this acess can be either permanent or temporary. If it is temporary a dialysis catheter is used to access the blood.Catheters are flexible tubes which are placed in large veins in the patient’s body. Catheters are most often used in emergencies for a small amount of time. A specific type of catheter called tunneled catheters can be used for longer time periods. If the acess is permanent, minor surgery is used to connect an artery to a vein. The artery and vein can be connected using blood vessels, or a synthetic bridge. When blood vessels are used it is called a arteriovenous fistula (AVF). This method is usually prefered because it has a lower chance of causing infection. However, the AVF can take months to start working. The synthetic bridges are called arteriovenous grafts (AVG). This method is sometimes preferable because it can be used only weeks after it is put into the body. However, infections are common with this method, and it is only a backup method if and AVF can not be used. The purpose of the connection made through an AVF or AVG is so that the vein can receive blood at a high pressure, which thickens the vein’s wall. The vein can then give very good blood flow rates. The blood flows from the access out of the body into a dialysis machine where dialysate is used to remove toxins from the blood. The blood then flows from the dialysis machine back into the body. This process takes 4 to 5 hours, and needs to be done 3 times a week, and is performed at a dialysis clinic.

Before Dialysis:

Before dialysis is performed there are some things that need to be checked. These include checking blood pressure, temperature, heart rate, breathing rate, weight, chest assessment, and examination of venous access.

Risks and Problems:

There are several risks associated with dialysis, both immediate and long-term. Immediate risks that could result from dialysis include: hypotension (when the blood pressure is below normal), infection, electrolyte imbalance, bleeding from the access site, nausea, vomiting, cramps, dialyzer reaction, air embolism (bubbles of air that block blood flow), and cardiac ischemia (the heart is not getting enough blood or oxygen), or arrhythmia (abnormal heart beat). Long term risks could include: dialysis-associated amyloidosis (a build up of amyloid in tissues and organs due to the use of dialysis), dialysis dementia (mental deterioration due to the use of dialysis), cardiovascular disease (such as heart valve disease, coronary arteries disease, etc.), autonomic neuropathy (a disease affecting the autonomic nervous system), and blood loss which causes an iron deficiency.       



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How The Wastes Come Out