Peritoneal dialysis

• 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, 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 hygiene 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. Peritonitis is the most common serious complication, but with good technique can usually be avoided. Infections of the catheter's exit site or "tunnel" (path from the peritoneum to the exit site) are less serious. 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).

Advantages and disadvantages of peritoneal dialysis

Advantages• Can be done at home. • Relatively easy to learn. • Easy to travel with, bags of solution are easy to

take on holiday. • Fluid balance is usually easier than on

hemodialysis • Theoretically better to start dialysis on, as native

urine output is maintained for longer than on hemodialysis.

• Excluding kidney transplant, PD is first choice method in treating chronic kidney failure.

Disadvantages• Requires a degree of motivation and

attention to cleanliness while performing exchanges.

• Possible complications

Side-effects and complications• Peritoneal dialysis requires access to the peritoneum. As

this access breaks normal skin barriers, and as people with renal failure generally have a slightly suppressed immune system, infection is a relatively common problem. With the development of prophylactic therapies, infection rates have been dramatically decreased.

• The infections can be localized, as in an exit-site or tunnel infection, where the infection is limited to the skin or soft tissue around the catheter. Infections that reach the peritoneum (peritonitis) are more serious, and will likely require antibiotics and/or supportive care. If the peritonitis is severe, removal of the catheter and a change of renal replacement therapy modality to hemodialysis may be necessary. Occasionally, severe peritonitis may be life-threatening.

• Because external infections can travel into the peritoneum, it is crucial that the any signs of infection at the exit site be called to the attention of a health-care provider.

• Signs of infection include redness, tenderness, and drainage.

• Quick treatments of exit site infections are very important to avoid the more serious complications that may jeopardize health, continued use of PD, or even life.

• Long term peritoneal dialysis can cause changes in the peritoneal membrane, making it less permeable and causing it to no longer act as a dialysis membrane as well as it used to.

• This loss of function can manifest as a loss of dialysis adequacy, or poorer fluid exchange (also known as ultrafiltration failure). It may also cause diabetes because of the glucose levels that are in the 'bags'

• Other complications that can occur are fluid leaks into surrounding soft tissue, often the scrotum in males.

• Hernias are another problem that can occur due to the abdominal fluid load. These often require repair before peritoneal dialysis is recommenced.

• Also, a common issue that arises in PD patients is the accumulation of fibrin in the PD effluent. This can cause draining and/or filling issues if too much collects in or around the catheter inside the peritoneum. To break up the fibrin, Heparin must be injected into the bags of dialysate (generally 1mL Heparin per liter of dialysate) until the fibrin clears up.

• One sign of peritonitis is the accumulation of very large amounts of fibrin in the PD effluent.

Liver

StomachIntestines

UterusBladder

Rectum

Where is the peritoneum?