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In medicine, dialysis is a method for removing waste such as urea from the blood when the kidneys are incapable of this, i.e. in renal failure.

1 The decision to dialyse

In acute renal failure, dialysis is generally initiated when the renal function has deteriorated to an extent that it is threatening the body's physiology.

In chronic renal failure (or end-stage renal failure, ESRD), the problem is usually longstanding, and decision is based on the possibility of a renal transplant , complications of the malfunctioning kidney (e.g. hyperkalemia, uremia) and personal factors (such as tiredness due to the uremia).

2 Types of dialysis

The two types of dialysis are hemodialysis and peritoneal dialysis.

• In hemodialysis, the patient's blood is passed through a tube into a machine that filters out waste products. The cleansed blood is then returned to the body.
• In peritoneal dialysis, a special solution is run through a tube into the peritoneal cavity, the abdominal body cavity around the intestine. The fluid is left there for a while to absorb waste products, and then removed through the tube.

3 Peritoneal dialysis

There are three types of peritoneal dialysis. Continuous ambulatory peritoneal dialysis (CAPD), the most common type, needs no machine and can be done at home. Continuous cyclic peritoneal dialysis (CCPD) uses a machine and is usually performed at night when the person is sleeping. Intermittent peritoneal dialysis (IPD) uses the same type of machine as CCPD, but is usually done in the hospital because treatment takes longer. Prior to any peritoneal dialysis, a catheter is placed in the patient's abdomen, running from the peritoneum out to the surface, near the navel. This is done as a short surgery.

CAPD is typically done in the patient's home and workplace, but can be done almost anywhere; a clean area to work, a way to elevate the bag of dialysis fluid and a method of warming the fluid are all that is needed. The main consideration is the very high potential for infection with an open catheter; peritonitisPeritonitis is infection (or inflammation) of the peritoneum, which is a two-layered membrane covering both the surfaces of the organs that lie in the abdominal cavity and the inner surface of the abdominal cavity itself. It is frequently life-threatening is a common complication, as are infections of the catheter exit site or "tunnel" (path from the peritoneum to the exit site). Because of this, patients are advised to take a number of precautions against infection.

Step-by-step description of peritoneal dialysis (a CAPD exchange):

1. The supplies and materials needed for an exchange are gathered in one clean location. Notable amongst these is a bag of dialysis fluid (also called dialysis solution), a solution comprised of a known amount of a glucoseGlucose a simple monosaccharide sugar, is one of the most important carbohydrates and is used as a source of energy in animals and plants. Glucose is one of the main products of photosynthesis and starts respiration. The natural form (D-glucose) is also r dissolved in water. The strength of this solution determines the osmotic gradient, and therefore the amount of water that diffuses out of the bloodstream. Common strengths of glucose are 0.5%, 1.5%, 2.5% and 4.25%. 1.5% is approximately fluid-neutral; it neither adds nor removes fluid and is used for patients who are primarily concerned with waste removal rather than fluid regulation. Higher concentrations lead to greater water removal. Electrolytes are also present in the fluid to maintain proper body levels. Patients weigh themselves, and measure temperature and blood pressure daily to determine whether the body is retaining fluid and, thus, what strength of fluid to use. Dialysis fluid typically comes premixed in a disposable bag-and-tube apparatus; no additional equipment is needed. The apparatus consists of two bags, one empty and one with the fluid, connected via flexible tubing to a Y-shaped fitting. The bag is heated to body temperature, to avoid causing cramping. Dry heat is used; common methods include microwavesA microwave oven is a kitchen appliance employing microwave radiation to cook food. History The idea for using microwaves to cook food was discovered by Percy Spencer who was working for Raytheon and was building magnetrons for radar sets. One day he was, heating pad s and solar radiationSolar radiation is radiant energy emitted by the sun, particularly electromagnetic energy. About half of the radiation is in the visible short-wave part of the electromagnetic spectrum. The other half is mostly in the near- infrared part, with some in the (often using the dashboard of a car, for instance while travelling).
2. The patient, who performs the entire procedure themselves, dons a disposable surgical maskA surgical mask is designed to be worn by health professionals during surgery and at other times to catch the bacteria shed from the wearer's mouth and nose. Outside health care facilities, simple, inexpensive surgical masks are commonly worn in heavily p, scrubs their hands using antibacterial soap, and tucks a clean towel into the waistband of their pants to protect their clothing. The bag of dialysis fluid is removed from the protective packaging, and is hung from an IV stand or other elevated location, such as a coat hook. The tubing attached to the bag of fluid is uncoiled, and the second (empty) bag is placed on the floor. The Y-shaped connector is attached to the catheter tip; a protective cap must be removed from both of these before the connection is made, and the two portions of the connector are not permitted to touch anything, to avoid possible contamination.
3. Once connected to the system, the patient clamps the tubing connected to the full bag of dialysis fluid and then releases the twist valve located in the tip of their catheter; this permits fluid to flow into or out of the peritoneal cavity. Because the full bag of fluid is clamped off but the empty bag is not, the effluent (used dialysis fluid) from within the peritoneum can drain out of the catheter and into the lower, waste bag. Emptying the abdomen of fluid takes approximately fifteen minutes, and the patient is free to perform tasks such as reading, watching television and editing a Wikipedia article about dialysis.
4. When the abdomen has drained, the lower, drain, bag is clamped off. The twist valve in the catheter is also closed. The clamp is then removed from the upper tubing, permitting dialysis fluid to drain out. The clamp to the drain bag is briefly opened and some fluid is drained directly from the upper bag into the lower bag. This clears the line of air and other impurities. The drain line is then clamped off and the twist valve on the catheter end is opened. This permits fluid to enter the peritoneum. Filling the abdomen with fresh fluid takes about fifteen minutes, and the patient enjoys the same freedoms as while draining.
5. Once the entire bag of fluid (an amount varying primarily based on body size, ranging from 1500 to 3000 mL) has been introduced to the abdomen, the patient then recleans their hands (typically using an antiseptic alcohol-based cleanser) and puts the surgical mask on. The Y-connector is detached from the catheter tip and a protective cap is placed on the end of the catheter.
6. The effluent is inspected after a dialysis exchange is complete; a cloudy effluent indicates probable peritoneal infection. The effluent is drained into a toilet, and the various dialysis supplies are discarded with normal garbage.