In medicine, peritoneal dialysis is a method for removing waste such as urea and potassium from the blood, as well as excess fluid, when the kidneys are incapable of this (i.e. in renal failure). It is a form of renal dialysis, and is thus a renal replacement therapy.
Peritoneal dialysis works on the principle that the peritoneal membrane that surrounds the intestine, can act as a natural semipermeable membrane (see dialysis), and that if a specially formulated dialysis fluid is instilled around the membrane then dialysis can occur, by diffusion. Excess fluid can also be removed by osmosis, by altering the concentration of glucose in the fluid.
Dialysis fluid is instilled via a peritoneal dialysis catheter, (the most common type is called a Tenckhoff Catheter) which is placed in the patient's abdomen, running from the peritoneum out to the surface, near the navel. Peritoneal dialysis catheters may also be tunnelled under the skin and exit alternate locations such as near the rib margin or sternum (called a presternal catheter), or even up near the clavicle. This is done as a short surgery. The exit site is chosen based on surgeon's or patient's preference and can be influenced by anatomy or hygeine issues.
Peritoneal dialysis 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 potential for infection with a catheter; peritonitis is a commonest serious complication, and infections of the catheter exit site or "tunnel" (path from the peritoneum to the exit site) are less serious but more frequent. Because of this, patients are advised to take a number of precautions against infection.
Types of 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.Exchanges of fluid are done throughout the day, usually four exchanges a day.
- 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 - if done overnight is called Nocturnal intermittent peritoneal dialysis (NIPD).
Peritoneal Signs
- guarding
- pain when hand released after palpation
Peritonitis is not specific unless the cause of inflammation identified.
Rebound tenderness is a clinical sign that a doctor may detect in physical examination of a patient's abdomen. It refers to pain that is felt after the examiner's hand is removed from an area (as distinct from tenderness, which is pain felt when the examiner's hand touches an area).
It represents aggravation of the parietal layer of peritoneum by stretching or moving.
Rebound is regarded as one of the classic local signs of peritonitis from diseases such as appendicitis. The others are tenderness and guarding.
However, in recent years the value of rebound tenderness has been questioned, since it may not add any diagnostic value beyond the observation that the patient has severe tenderness.
Blumberg's sign is a sign that is elicited during physical examination in medicine. It is indicative of peritonitis.
The abdominal wall is compressed slowly and then rapidly released. Presence of pain makes the sign positive. It is very similar to rebound tenderness and might be regarded by some authors as the same thing, or at least a particular application of it.
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hepatoportoenterostomy
(Kasai procedure)
This operation is used in biliary atresia where direct anastomosis of the biliary tree and gut cannot be achieved.
This rationale for this operation is that minute bile duct remnants, representing residual channels, may be present in the fibrous tissue of the porta hepatis, and in direct communication with the intrahepatic ductule system.
The operation involves transection of the porta hepatis with anastomosis of the bowel mucosa to the proximal section of the transection so as to allow drainage of the bile.
