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Info & Treatments for Kidney Stones & Kidney Disease

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Dialysis, the artificial removal of accumulated waste materials and toxins from the blood as a treatment for acute renal failure, is performed in two different ways, called hemodialysis and peritoneal dialysis. Hemodialysys, the more common method, makes use of a dialysis machine and is almost always done in a clinical or hospital setting. The patient's blood is removed from his body using a catheter, treated by the machine, and returned to the patient's body with accumulated wastes cleaned from it. In this way, a patient can be kept alive and in fairly good health despite the loss of kidney function.


The process of hemodialysis involves running the patient's blood through a machine that cleanses it of waste materials. The machine works using the principle of diffusion. This principle holds that solutes dissolved in a liquid will move from an area of higher concentration to one of lower concentration, even if the liquids are not actually mixed, provided they are not completely separated by impermeable barriers or distance.

Hemodyalisis employs a liquid called a dialysate, which is composed with a view to what contaminates need to be removed from the blood and which other solutes need to remain as they are.

The dialysate is low in concentration of, or completely lacking in, materials to be removed from the blood. A semi-permeable membrane separates the blood from the dialysate, and these two fluids are circulated through the dialyzer chamber in opposite directions.

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Contaminants flow across the membrane from the blood to the dialysate. The used dialysate is then returned to a container and replaced with fresh dialysate, while the cleansed blood is returned to the patient's body. The primary substances to be removed from the blood in dialysis are urea (or blood urea nitrogen -- BUN), creatinine, which is a waste product generated by the muscles as part of metabolism, and accumulated minerals such as phosphorus, potassium, and calcium. The entire process of hemodialysis requires about four hours for one treatment. It needs to be done at least once a week, although recent studies have shown that more frequent dialysis has benefits in the treatment of renal disease, up to seven times per week or once per day.


Because sufferers from renal failure often pass little or no urine, the blood accumulates excess water as well as waste materials. Hemodialysis usually seeks to remove this excess water from the blood alone with BUN, creatinine, and other solutes. If too much water is removed during the process, or if the water is removed too quickly, the patient can suffer from low blood pressure, fatigue, cramps, nausea, and headaches. These symptoms can occur during treatment and can endure after the treatment is completed. This is a common side-effect of dialysis and is referred to sometimes as a "dialysis hangover." In addition, because the blood is exposed during the process, hemodialysis can lead to various types of blood-borne infections if the blood is brought into contact with microbes. Antiseptic procedures are extremely important in hemodyalisis as in surgery for this reason.

Hemodialysis vs. Peritoneal Dialysis

The other form of dialysis, peritoneal dialysis, makes use of the peritoneum (the membrane surrounding the abdominal cavity) instead of an artificial membrane. The blood is not removed from the body. Each method has advantages and disadvantages. With hemodialysis, the process is quicker and more efficient, and so it can be done less often and take up less time during the day. On the downside, hemodialysis does not lend itself to use by the patient at home. It is normally done in an outpatient setting, and while the process is taking place the patient is attached to the machine and can't do much besides undergo the dialysis.


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