CAPD stands for continuous ambulatory peritoneal dialysis, a form of kidney dialysis you perform yourself throughout the day without a machine. Instead of filtering your blood through an external device at a hospital, CAPD uses the natural lining of your abdomen as a filter. A cleansing fluid flows into your belly through a permanently placed catheter, sits there while it absorbs waste products from your blood, and then drains out. You repeat this process about four times a day, and you can do it at home, at work, or anywhere clean and dry.
How Your Abdomen Filters Blood
Your abdomen is lined with a thin membrane called the peritoneum, which is rich with tiny blood vessels. In CAPD, this membrane acts as a natural filter. When cleansing fluid (called dialysate) fills the space around your abdominal organs, waste products and excess fluid pass from your blood vessels through the peritoneum and into the dialysate. After several hours, you drain the fluid out, and it carries those waste products with it.
This is fundamentally different from hemodialysis, where blood is pumped out of your body, run through a machine that filters it, and returned through needles in your arm. With CAPD, the filtering happens inside your body, powered by nothing more than gravity and the chemistry of the dialysate solution.
What an Exchange Looks Like
Each cycle of filling, dwelling, and draining is called an exchange. You connect a bag of fresh dialysate to your catheter, let gravity pull the fluid into your abdomen, and then go about your day while it sits there absorbing waste. This sitting period is called the dwell time. When the dwell is over, you drain the used fluid into an empty bag and refill with a fresh solution.
Most people do four exchanges per day, with each drain-and-refill taking about 30 to 40 minutes. Three of these happen during waking hours, and one runs overnight with a longer dwell time while you sleep. Between exchanges, the catheter stays capped under your clothing, and you’re free to work, exercise, or handle daily responsibilities while the fluid does its job inside your belly.
Equipment You’ll Use
The central piece of equipment is a soft, flexible catheter that a surgeon permanently places through your abdominal wall. Most are double-cuffed silicone tubes that stay in place for the duration of your treatment, sometimes years. The catheter connects to your dialysate bags through a transfer set, which is either a simple straight connector or a Y-shaped system that lets you disconnect between exchanges. The Y-set and double-bag systems are designed to reduce the chance of introducing bacteria during connections.
Your supplies arrive in boxes, typically delivered to your home on a regular schedule. Each exchange uses a pre-filled bag of sterile dialysate and a drainage bag. There’s no large machine involved, which is one reason many people prefer CAPD over other forms of dialysis.
Lifestyle Benefits Over Hemodialysis
Standard hemodialysis requires traveling to a dialysis center three times a week for sessions lasting about four hours each, plus travel and waiting time. CAPD eliminates that entirely. Research comparing the two approaches consistently finds that peritoneal dialysis patients report higher satisfaction with their social lives and feel less burdened by treatment. The hospital schedule of hemodialysis can interfere with work, family time, and social activities in ways that home-based CAPD generally does not.
CAPD also avoids needles. Hemodialysis requires repeated needle sticks into a surgically created access point in your arm, which many patients find painful and stressful. With CAPD, everything flows through the abdominal catheter. Travel is more flexible too, since you can pack your supplies and perform exchanges in a hotel room or a relative’s home.
Who Can and Can’t Do CAPD
Most people with kidney failure can choose CAPD, but certain conditions rule it out. Inflammatory bowel diseases like Crohn’s disease or ulcerative colitis, active abdominal infections, and end-stage liver disease with fluid buildup in the belly are all contraindications. An unrepaired hernia is the main structural barrier, since the pressure of fluid in the abdomen could make it worse.
People who have ostomies or feeding tubes may face challenges but aren’t automatically excluded. If you’ve had complex abdominal surgeries in the past, scar tissue (adhesions) can interfere with catheter placement and fluid flow, though surgeons can sometimes work around this using a camera-guided approach. A BMI above 35 can also cause problems, as internal abdominal fat may block the catheter tip and restrict flow.
The Main Risk: Peritonitis
The most significant complication of CAPD is peritonitis, an infection of the peritoneal lining. It happens when bacteria enter the abdomen, usually through the catheter during an exchange. The most common cause is “touch contamination,” meaning you or a helper accidentally break sterile technique while connecting or disconnecting bags. Skin bacteria, particularly staphylococcal species that naturally live on your hands and skin, are responsible for more than half of infections.
The warning signs are distinct: new abdominal pain, fever, and cloudy drainage fluid. If you notice any of these, you need to contact your dialysis team immediately for evaluation. Peritonitis is treatable, but repeated episodes can damage the peritoneal membrane over time and eventually force a switch to hemodialysis. In one large long-term study, peritonitis accounted for 23% of cases where patients had to stop peritoneal dialysis.
Less commonly, infections can originate from inside the abdomen itself. Conditions like diverticulitis or appendicitis can introduce gut bacteria into the peritoneal space, causing a different pattern of infection that typically involves different organisms.
Long-Term Outlook
A 25-year retrospective analysis found that the median time patients stayed on peritoneal dialysis was about 57 months, or just under five years. At the one-year mark, 88% of patients were still on PD. By three years, that dropped to 69%, and by five years, 48% remained on the therapy. The rest transitioned to hemodialysis or received a kidney transplant.
The leading reason people eventually switch is that dialysis becomes inadequate, meaning the peritoneal membrane can no longer filter waste effectively enough. This accounted for about 34% of transitions in the study. Peritonitis was the second most common reason at 23%. Caregiver or patient burnout, a less discussed but real factor, contributed to about 8% of cases. Performing exchanges every day for years is a genuine psychological and logistical commitment.
Survival rates at one, three, five, and seven years were 89%, 73%, 60%, and 47%, respectively. These numbers reflect a population with kidney failure overall, not just the dialysis method itself.
Diet on CAPD
One practical advantage of CAPD is that dietary restrictions tend to be less strict than with hemodialysis. Because the filtering process runs continuously rather than in three weekly bursts, waste products and electrolytes stay more stable between exchanges.
One notable difference is potassium. CAPD can actually remove too much potassium from your blood, so you may need to eat more potassium-rich foods like bananas, oranges, potatoes, and tomatoes. This is the opposite of hemodialysis, where potassium restriction is common. Protein needs are higher on CAPD as well, since some protein is lost into the dialysate during each exchange. Dietitians typically recommend focusing on high-quality protein sources like meat, poultry, fish, and eggs, which produce less waste for your body to filter.