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Dialysis is the removal of wastes and other undesirable substances from the blood by means of a special membrane that is selective in what it allows to cross. In the healthy body, this task is performed by the kidneys. Let's review three types of dialysis.
Hemodialysis
In a patient suffering from temporary or permanent kidney failure, cleansing of the blood can be done with an artificial kidney machine; this is known as hemodialysis. Two plastic tubes, one connected to an artery and one to a vein, are implanted in the patient's arm or leg. During dialysis, which can take three to five hours per treatment, blood from the artery tube enters the machine and comes into contact with a thin membrane. Wastes from the blood pass through the membrane into circulating fluid on the other side of the membrane. The blood cells themselves cannot cross the membrane. The cleaned blood is then piped back into the patient through the vein tube.
Peritoneal Dialysis
In peritoneal dialysis, the patient's own peritoneum (lining of the abdominal cavity) is used as the dialysis membrane. A sterile plastic catheter (tube) is passed into the abdominal cavity, and a solution of glucose (a form of sugar) and mineral salts is periodically injected into and withdrawn from the cavity. The fluid comes into contact with delicate blood vessels in the peritoneum.
Because of the difference in concentration of certain chemical elements in the blood and the dialysis solution, wastes from the blood are forced through the membrane of the peritoneal wall. The dialysis liquid is periodically withdrawn and replaced with a fresh solution.
Continuous Ambulatory Peritoneal Dialysis
A new method called continuous ambulatory peritoneal dialysis has greatly lowered the cost of dialysis and made the procedure more convenient. It can be done at home by the patient without the complex equipment and the skilled supervision that has made machine dialysis so expensive.
A tube is surgically implanted in the patient, just below the navel. About every four to five hours and just before bedtime, the patient drains out the old fluid and empties a bag of fresh dialysis fluid into the abdominal cavity through a tube. The fluid remains in the cavity, soaking up wastes from the blood, while the patient sleeps or goes about his or her usual daily activities. The procedure enables the patient to be independent and mobile.
This information is solely for informational purposes. IT IS NOT INTENDED TO PROVIDE MEDICAL ADVICE. Neither the Editors of Consumer Guide (R), Publications International, Ltd., the author nor publisher take responsibility for any possible consequences from any treatment, procedure, exercise, dietary modification, action or application of medication which results from reading or following the information contained in this information. The publication of this information does not constitute the practice of medicine, and this information does not replace the advice of your physician or other health care provider. Before undertaking any course of treatment, the reader must seek the advice of their physician or other health care provider.
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Please copy/paste the following text to properly cite this How Stuff Works article:
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