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 no longer do the job adequately.
A cleansing fluid flows through a tube (catheter) into part of your abdomen and filters waste products from your blood. After a prescribed period of time, the fluid with filtered waste products flows out of your abdomen and is discarded.
Peritoneal dialysis differs from hemodialysis, a more commonly used blood-filtering procedure. With peritoneal dialysis, you can give yourself treatments at home, at work or while traveling.
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 a reliable caregiver.
Why it's done
Dialysis is required if your kidneys don't function adequately on their own. Kidney damage generally progresses over a number of years as a result of long-term conditions, such as:
- High blood pressure (hypertension)
- Kidney inflammation (glomerulonephritis)
- Multiple cysts in the kidneys (polycystic kidney disease)
The benefits of peritoneal dialysis compared with hemodialysis can include:
- Greater lifestyle flexibility and independence. These can be especially important if you work, travel or live far from a hemodialysis center.
- More flexible dietary guidelines. Peritoneal dialysis is done more continuously than hemodialysis, resulting in less accumulation of potassium, sodium and fluid.
- More stable blood chemistry and body hydration. Peritoneal dialysis doesn't require intravenous (IV) access, which can disrupt your circulation and fluid levels.
- Longer lasting residual kidney function. People who use peritoneal dialysis might retain kidney function slightly longer than people who use hemodialysis.
Your doctor will discuss with you the type of dialysis that's best for you. Factors to consider include:
- Your kidney function, as measured by blood and urine tests
- Your overall health
- Your personal preferences
- Your home situation
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, and 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
- Protein malnutrition
- Critical illness
Most people who start dialysis with peritoneal dialysis will eventually experience a decline in kidney function and will need hemodialysis or 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 several hundred extra calories a day, 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 receive training on what peritoneal dialysis involves and how to use the equipment.
You'll also 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 at least two weeks before starting peritoneal dialysis treatments to give the catheter site time to heal. Complete healing of the catheter site can take up to two months.
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 (capillaries) in the lining of your abdominal cavity (peritoneum)
- 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 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:
- 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 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 you're 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.