Choosing between Continuous Ambulatory Peritoneal Dialysis and Assisted Peritoneal Dialysis

As a patient needing dialysis, you have two treatment options – Hemodialysis (HD) and Peritoneal Dialysis (PD). Both options remove extra fluid and molecules that gather inside the body when the kidney fails.(1) The choice of dialysis depends on your preference, lifestyle and work schedule. Overall, PD is more flexible and convenient. It can be done at your own home and does not require 3-4 visits per week to a dialysis center as seen with HD. PD requires you and a family member to learn the process and work closely with your dialysis team and nephrologist.


Before you begin PD, a surgeon will insert a soft catheter through the skin that passes into a layer of the stomach called peritoneum. This layer acts as a thin layer of tissue that allows exchange of fluid, electrolytes and harmful substances between blood and a sugar containing fluid placed inside the stomach through the catheter. The sugar containing fluid, called dialysate attracts fluid and electrolytes from the blood and keeps it in the peritoneal cavity/stomach. The waste products collected in the peritoneal cavity can then be drained.(2)

The process of filling the stomach with dialysate and draining it is called an “exchange” and the time the dialysate remains in the peritoneal cavity is the “dwell time”. A typical PD prescription will include both and requires 4-6 exchanges per day with a dwell time of 4-6 hours per exchange. During the dwells you will be able to perform every day

activities with the exception of contact sports. Before you begin PD, you will receive enough training to allow you to fill and drain dialysate through the catheter at home.


There are 2 types of PD: Continuous Ambulatory Peritoneal Dialysis (CAPD) and Assisted Peritoneal Dialysis (APD). Depending on the type of PD you choose you will do many exchanges throughout the day or a few exchanges at night.

CAPD: You do not need a machine if you choose this type of PD. You will fill your stomach with dialysate and drain it out after 4-6 hours with gravity. CAPD involves several exchanges during the course of each day and this may not be convenient for people who work during the day. No matter the type of PD a patient chooses, all patients are trained in CAPD in case of power outages and emergencies.

APD: This type of PD requires a machine that does exchanges for you while you sleep at night. It includes the same number of exchanges as CAPD, but shorter dwell times. In the morning, you fill your stomach and the dialysate remains in the stomach for the entire day, which will be your longest dwell time.

What’s the difference between CAPD and APD?The ability to exchange and clear fluid and waste from the blood is the same in both CAPD and APD. But, there are some features, which can help you, decide which type of PD suites you.

A major complication associated with PD is introduction of harmful bacteria into the peritoneal cavity, called peritonitis. This complication can lead to significant suffering and is a common reason for failure of PD. The number of peritonitis cases has been found to be lower in APD than CAPD.(3) Not surprisingly, APD also has lower incidence of dialysis-related hospital admissions.4 However, the number of local skin infection at the site of the catheter was the same between both APD and CAPD.(5)

One study that examined quality-of-life in patients who chose CAPD or APD found a lot more time for family, work and social activities with APD than CAPD – which usually meant the patients followed their treatment instructions better. The study also found more sleep related problems with APD than CAPD. For those considering cost, there is no big difference in both CAPD and APD with a daily cost of $61 and $75 respectively.(6)

Overall, it is important for you to know that there is no real difference between the effect of CAPD and APD, and your preference remains the main point for choosing one modality of PD over another.(7,8)

Afreen I. Shariff, MD, is a resident in the Department of Internal Medicine at East Carolina University in Greenville, NC.

Tejas Desai MDTejas Desai, MD, is Assistant Professor in the Division of Nephrology and Hypertension and the Associate Program Director of the Internal Medicine Residency Program at East Carolina University in Greenville, NC. Dr. Desai serves on the AAKP Board of Directors.




1. Daugirdas, JT; Blake PG; Ing TS (2006). “Physiology of Peritoneal Dialysis”. Handbook of dialysis. Lippincott Williams & Wilkins. pp. 323

2. Best practices: evidence-based nursing procedures. Lippincott Williams & Wilkins. 2007. pp. 471–7

3. Huang JW, Hung KY, Yen CJ, Wu KD, Tsai TJ. Comparison of infectious complications in peritoneal dialysis patients using either a twin-bag system or automated peritoneal dialysis. Nephrol Dial Transplant2001; 16: 604–607

4. De Fijter CWH, Oe LP, Nauta JJP et al. Clinical efficacy and morbidity associated with continuous cyclic compared with continuous ambulatory peritoneal dialysis. Ann Intern Med1994; 120: 264–271

5. Rodriguez-Carmona A, Fontán MP, Falcón TG, Rivera CF, Valdés F. A comparative analysis on the incidence of peritonitis and exit-site infection in CAPD and automated peritoneal dialysis. Perit Dial Int1999; 19: 253–258

6. Bro S, Bjorner JB, Jensen PT et al. A prospective, randomized multicenter study comparing APD and CAPD treatment. Perit Dial Int1999; 19: 526–53.

7. Liakopoulos V, Dombros N. Patient selection for automated peritoneal dialysis: for whom, when? Perit Dial Int 2009; 29(Suppl 2):S102–7

8. Mehrotra R, Chiu YW, Kalantar–Zadeh K, Vonesh E. The outcomes of continuous ambulatory and automated peritoneal dialysis are similar. Kidney Int 2009; 76:97–107