Peritoneal dialysis (PD) is another form of dialysis modality for the patients with kidney failure. It is widely accepted and effective. It is the most common method of dialysis done at home.
Intermittent peritoneal dialysis (IPD) is a valuable and effective dialysis option for short term dialysis in hospitalized patients with acute kidney failure, in children and during emergencies or initial treatment of ESKD. In IPD, a special catheter with multiple holes is inserted into the patient’s abdomen through which a special solution called the dialysate is infused into the abdominal cavity or peritoneal space. The dialysate absorbs waste products and excess fluids from the patient’s blood. After some time, the fluid is drained and the process is repeated several times in a day.
C – Continuous: The process is uninterrupted (treatment without stopping for 24 hours a day, 7 days a week).
A – Ambulatory: The patient can walk around and performroutine activities.
P – Peritoneal: The peritoneal membrane in the abdomen works as a filter.
D – Dialysis: The method of purification of blood.
CAPD is a form of dialysis which can be carried out by a person at home without the use of a machine. As CAPD provides convenience and independence it is a popular dialysis modality in many countries.
CAPD catheter:The permanent access for peritoneal dialysis (CAPD catheter) is a soft thin flexible silicon rubber tube with numerous side holes. It is surgically inserted into the patient’s abdomen through the abdominal wall, about an inch below and to the side of the navel or belly button. The CAPD catheter is inserted about 10 to 14 days before CAPD starts. The PD catheter is the “life line” of CAPD patients, just as the AV fistula is to a patient on haemodialysis.
In CAPD, special fluid (dialysate) is infused into the abdominal cavity and is kept there for a period of time, after which it is drained. This process of fill, dwell and drain is called an exchange.
Fill: Peritoneal dialysis fluid from the sterile PD bag is infused by gravity, through sterile tubings connected to the PD catheter, into the abdominal cavity. Usually, 2 liters of fluid is infused. The bag emptied of PD fluid is rolled up and tucked in the patient’s inner wear until the next exchange.
Dwell: The period of time in which PD fluid remains inside the abdominal cavity is called the dwell time. This lasts for about 4 to 6 hours per exchange during the day and 6 to 8 hours at night. The process of cleaning the blood takes place during dwell time. The peritoneal membrane works like a filter allowing waste products, unwanted substances and excess fluid to pass from blood into the PD fluid. The patient is free to walk around during this time (hence the term, ambulatory).
Drain:When the dwell time is completed, the PD fluid is drained into the empty collection bag (which had been rolled up and tucked in the patient’s inner clothing). The bag with the drained fluid is weighed and discarded; the weight is recorded. The drained fluid should be clear. Drainage and replacement with fresh solution takes about 30 to 40 minutes. Exchanges may be done from 3 to 5 times during the day and once during the night. Fluid for the night exchange is left in the abdomen overnight and drained in the morning. Strict aseptic precautions should be observed when performing CAPD.
Automated peritoneal dialysis (APD) or continuous cycling peritoneal dialysis (CCPD) is a form of PD treatment done at home using an automated cycler machine. The machine automatically fills and drains the PD fluid from the abdomen. Each cycle usually lasts for 1-2 hours and exchanges are done 4 to 5 times per treatment. The treatment lasts about 8 to 10 hours, usually at night, while the patient is asleep. In the morning, the machine is disconnected and 2 to 3 liters of PD fluid are usually left in the abdominal cavity. This fluid is drained the following evening before the next treatment is started. APD is advantageous since it allows the patient to go about regular activities during the day. Also, since the PD bag is connected and detached from the catheter only once a day, the procedure is more comfortable and carries less risk of peritonitis. However, APD may be expensive in some countries and can be a rather complex procedure for some patients.
PD fluid (dialysate) is a sterile solution containing minerals and glucose (dextrose). Glucose in the dialysate allows removal of fluid from the body. Depending on the concentration of glucose, there are three kinds of dialysate available in India and in most areas worldwide (1.5%, 2.5% and 4.5%).The glucose concentration is selected for individual patients depending on the amount of fluid that needs to be removed from the body. Newer PD fluids are available in some countries which contain icodextrin instead of glucose. Icodextrin-containing solutions remove body fluids more slowly and are recommended for diabetic or overweight patients.
CAPD solution bags are available in different volumes ranging from 1000 to 2500 ml.
The main complications of CAPD involve infections. The most common infection is peritonitis, an infection of the peritoneum Pain in the abdomen, fever, chills and cloudy/turbid outflow of PD fluid (effluent) are common presentations of peritonitis. To avoid peritonitis, CAPD should be done under strict aseptic precautions and constipation should be avoided. The treatment of peritonitis includes broad spectrum antibiotics, culture of the PD effluent (to help select appropriate antibiotics) and, in a few patients, removal of the PD catheter. Infection at the exit site of the PD catheter is another infection that may also develop.
Other problems that may occur in CAPD are abdominal distention, weakening of the abdominal muscles causing hernia, fluid overload, scrotal oedema, constipation, back pain, poor outflow drainage, leakage of fluid and weight gain.
The patient on CAPD should immediately contact dialysis nurse or doctor when any of the following occurs: