Peritoneal dialysis (per-ih-toe-NEE-ul die-AL-uh-sis) is a way to remove waste products from your blood when your kidneys can't adequately do the job any longer. This procedure filters the blood in a different way than does the more common blood-filtering procedure called hemodialysis.
During peritoneal dialysis, a cleansing fluid flows through a tube (catheter) into part of your abdomen. The lining of your abdomen (peritoneum) acts as a filter and removes waste products from your blood. After a set period of time, the fluid with the filtered waste products flows out of your abdomen and is discarded.
These treatments can be done at home, at work or while traveling. But peritoneal dialysis isn't an option for everyone with kidney failure. You need manual dexterity and the ability to care for yourself at home, or you need a reliable caregiver.
Why it's done
You need dialysis if your kidneys no longer function well enough. Kidney damage generally progresses over a number of years as a result of long-term conditions, such as:
- High blood pressure
- Kidney inflammation (glomerulonephritis)
- Multiple cysts in the kidneys (polycystic kidney disease)
In hemodialysis, blood is removed from the body, filtered through a machine and then the filtered blood is returned to the body. Hemodialysis is typically done in a health care setting, such as a dialysis center or hospital, though it can sometimes be done at home.
Although both types of dialysis can effectively filter your blood, the benefits of peritoneal dialysis compared with hemodialysis include:
- Greater lifestyle flexibility and independence. These can be especially important if you work, travel or live far from a hemodialysis center.
- A less restricted diet. Peritoneal dialysis is done more continuously than hemodialysis, resulting in less accumulation of potassium, sodium and fluid. This allows you to have a more flexible diet than you could have on hemodialysis.
- Longer lasting residual kidney function. People who use peritoneal dialysis might retain kidney function slightly longer than people who use hemodialysis.
Talk with your doctor about which type of dialysis might be best for you. Factors to consider include:
- Your kidney function
- Your overall health
- Your personal preferences
- Your home situation
- Your lifestyle
Peritoneal dialysis may be the better option if you:
- Can't tolerate the rapid changes of fluid balance associated with hemodialysis
- Want to minimize the disruption of your daily activities
- Want to work or travel more easily
- Have some residual kidney function
Peritoneal dialysis might not work if you have:
- Extensive surgical scars in your abdomen
- A large area of weakened abdominal muscle (hernia)
- Limited ability to care for yourself, or a lack of caregiving support
- Inflammatory bowel disease or frequent bouts of diverticulitis
It's also likely that people using peritoneal dialysis will eventually have a decline in kidney function that requires hemodialysis or a kidney transplant.
Complications of peritoneal dialysis can include:
- Infections. An infection of the abdominal lining (peritonitis) is a common complication of peritoneal dialysis. An infection can also develop at the site where the catheter is inserted to carry the cleansing fluid (dialysate) into and out of your abdomen. The risk of infection is greater if the person doing the dialysis isn't adequately trained.
- Weight gain. The dialysate contains sugar (dextrose). Absorbing some of the dialysate might cause you to take in hundreds of extra calories daily, leading to weight gain. The extra calories can also cause high blood sugar, especially if you have diabetes.
- Hernia. Holding fluid in your abdomen for long periods may strain your muscles.
- Inadequate dialysis. Peritoneal dialysis can become ineffective after several years. You might need to switch to hemodialysis.
If you have peritoneal dialysis, you'll need to avoid:
- Certain prescription and over-the-counter medications that can damage your kidneys, including nonsteroidal anti-inflammatory drugs.
- Soaking in a bath or hot tub, or swimming in a lake, pond, river or nonchlorinated pool — which increases the risk of infection. Showers and swimming in a chlorinated pool are generally acceptable.
How you prepare
You'll need an operation to insert the catheter that carries the dialysate in and out of your abdomen. The insertion might be done under local or general anesthesia. The tube is usually inserted near your bellybutton.
After the tube is inserted, your doctor will probably recommend waiting up to a month before starting peritoneal dialysis treatments to give the catheter site time to heal.
You'll also receive training on how to use the peritoneal dialysis equipment.
What you can expect
During peritoneal dialysis:
- The dialysate flows into your abdomen and stays there for a prescribed period of time (dwell time) — usually four to six hours
- Dextrose in the dialysate helps filter waste, chemicals and extra fluid in your blood from tiny blood vessels in the lining of your abdominal cavity
- When the dwell time is over, the solution — along with waste products drawn from your blood — drains into a sterile collection bag
The process of filling and then draining your abdomen is called an exchange. Different methods of peritoneal dialysis have different schedules of exchange. The two main schedules are:
- Continuous ambulatory peritoneal dialysis (CAPD)
- Continuous cycling peritoneal dialysis (CCPD)
Continuous ambulatory peritoneal dialysis (CAPD)
You fill your abdomen with dialysate, let it remain there for a prescribed dwell time, then drain the fluid. Gravity moves the fluid through the catheter and into and out of your abdomen.
- You may need three to five exchanges during the day and one with a longer dwell time while you sleep
- You can do the exchanges at home, work or any clean place
- You're free to go about your normal activities while the dialysate dwells in your abdomen
Continuous cycling peritoneal dialysis (CCPD)
Also known as automated peritoneal dialysis (APD), this method uses a machine (automated cycler) that performs multiple exchanges at night while you sleep. The cycler automatically fills your abdomen with dialysate, allows it to dwell there and then drains it to a sterile bag that you empty in the morning.
- You must remain attached to the machine for about 10 to 12 hours at night.
- You aren't connected to the machine during the day. But in the morning you begin one exchange with a dwell time that lasts the entire day.
- You might have a lower risk of peritonitis because you connect and disconnect to the dialysis equipment less frequently than you do with CAPD.
To determine the method of exchange that's best for you, your doctor will consider your medical condition, lifestyle and personal preferences. Your doctor might suggest certain modifications to individualize your program.
Many factors affect how well peritoneal dialysis works in removing wastes and extra fluid from your blood. These factors include:
- Your size
- How quickly your peritoneum filters waste
- How much dialysis solution you use
- The number of daily exchanges
- Length of dwell times
- The concentration of sugar in the dialysis solution
To check if your dialysis is removing enough waste products, your doctor is likely to recommend tests, such as:
- Peritoneal equilibration test (PET). This test compares samples of your blood and your dialysis solution during an exchange. The results indicate whether waste toxins pass quickly or slowly from your blood into the dialysate. That information helps determine whether your dialysis would be improved if the solution stayed in your abdomen for a shorter or longer time.
- Clearance test. A blood sample and a sample of used dialysis solution are analyzed to determine how much of a certain waste product (urea) is being removed from your blood during dialysis. If you still produce urine, your doctor may also take a urine sample to measure its urea concentration.
If the test results show that your dialysis schedule is not removing enough wastes, your doctor might change your dialysis routine to:
- Increase the number of exchanges
- Increase the amount of dialysate you use for each exchange
- Use a dialysate with a higher concentration of dextrose
You can improve your dialysis results and your overall health by eating the right foods, including foods low in sodium and phosphorus. A dietitian can help you develop an individualized meal plan. Your diet will be based on your weight, your personal preferences, and your remaining kidney function and other medical conditions, such as diabetes or high blood pressure.
Taking your medications as prescribed also is important for getting the best possible results. While receiving peritoneal dialysis, you'll likely need various medications to control your blood pressure, stimulate production of red blood cells, control the levels of certain nutrients in your blood and prevent the buildup of phosphorus in your blood.
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