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What is Haemodialysis?

Haemodialysis is a treatment for those patients whose kidneys cannot function any more. It is a way of cleansing the blood of toxins, extra salts and fluids through a dialysis machine called "artificial kidney". It helps maintain proper chemical balance such as potassium, sodium and chloride and keeps blood pressure under control.

How does it work?

During dialysis, two needles will be placed into the vascular access, one to remove the blood and the other to return cleansed blood to the body. You are connected (via tubing) to the dialysis machine through a vein in your arm, the blood is pumped from your body to a special filter called the dialyser, which is made of tiny capillaries.

Blood is continuously pumped through the dialyser, where waste products and excess water are removed. The blood becomes purified when the waste products diffuse from the blood across the membrane of these tiny capillaries. This purified blood is then returned to your body through larger tubes.

Haemodialysis is performed 3 times a week, with each session lasting about 3 to 5 hours, depending on the body size and medical condition. At the NKF, patients can choose Mondays, Wednesdays and Fridays or Tuesdays, Thursdays and Saturdays. They can also choose the morning, afternoon or evening session.

Things to take care...

Before and during dialysis, you need to clean the skin covering the access before inserting the needles to avoid infection. If you notice any signs of infection, inform the nurse immediately. Besides, you need to make sure that your blood is flowing and not clotting while on treatment, lightly touch the area to feel a pulse. It is important that the catheter be kept dry, even when you are taking a bath.

You also need to take care of your fistula or graft. You should not wear anything tight around the fistula/graft arm i.e. watches, bracelets, tight clothing, or carry heavy bags looped over the fistula/graft. Despite of checking that the fistula/graft is working by feeling for the buzzing sensation every morning and night, you should not allow non-dialysis staff to take blood or blood pressure on your fistula/graft arm. Observe for signs of infection, such as redness, oozing of blood or pus, swelling and heat, you need to contact the nurse immediately if there are any problems with your fistula/graft.

What is Peritoneal Dialysis?

Peritoneal dialysis (PD) is an alternative treatment to haemo-dialysis. A special sterile fluid is introduced into the abdomen through a permanent tube that is placed in the peritoneal cavity. The fluid circulates through abdomen to draw impurities from surrounding blood vessels in the peritoneum, and it is then drained from the body.

PD can be carried out at home, at work, or on trips, but requires careful supervision. PD gives patients more control. However, they need to work closely with the health care team including the nephrologist, dialysis nurse, dialysis technician, dietitian and social worker. The role of the PD patient and his/her family are very important. By learning more about the treatment, patients can work with the health care team to achieve the best possible results and lead an active life.

How does it work?

The walls of the abdominal cavity are lined with a membrane called the peritoneum, which allows waste products and extra fluid to pass from your blood into the dialysis solution. In PD, a soft tube called a catheter is used to fill the abdomen with a cleansing liquid called dialysis solution. The solution contains a type of sugar called dextrose that will pull waste and extra fluid into the abdominal cavity, will be exuded out of the body when the dialysis solution is drained. The used solution will be thrown away.
The process of draining and filling is called an exchange and takes about 30 to 40 minutes. The period when the dialysis solution is in the abdomen is called the dwell time. A typical schedule calls for four exchanges a day, each with a dwell time of 4 to 6 hours. Different types of PD have different schedules of daily exchanges.

Types of PD

There are two types of Peritoneal Dialysis: Continuous Ambulatory Peritoneal Dialysis (CAPD) and Automated Peritoneal Dialysis (APD).

You do not need a machine for CAPD. You simply need gravity to fill and empty your abdomen. The doctor prescribes the number of exchanges a patient needs, typically three or four exchanges during the day and one evening exchange with a long overnight dwell time while one sleeps. As the word "ambulatory" suggests, you can walk around with the dialysis solution in your abdomen.

An alternative to CAPD is Automated Peritoneal Dialysis (APD) where a machine called a cycler changes the dialysate solution during the night, usually while patients are asleep. This means that patients have to be attached to the machine for 8-10 hours.

Why APD?

APD is suggested to offer a number of unproven psychosocial benefits over CAPD. It relates directly to fewer connections and allows patient to lead a normal lifestyle during the day, particularly for workers, school pupils and those taking care of the elderly or debilitated patients. Additional benefits include the absence of fluid during the day, which possibly reduces back pain and body image difficulties. Performing APD at night in the supine position also results in reduced intra-abdominal pressures as compared with the upright position in CAPD.

APD is designed to be simple and is often performed in the bedroom. The machines are user-friendly. Before going to sleep, the machine needs to be loaded with fluid. It will then perform a number of cycles throughout the night. The fluid is drained away into a large drainage bag for disposal. Often, the machine will provide a last fill of fluid, which stays inside the tummy until the following night when it is drained away.

Peritoneal dialysis units worldwide are increasingly adopting APD. It is estimated that one quarter of the world's peritoneal dialysis patients are now on APD. The use of cyclers in North America has increased from 10% in 1990 to 43% in 1997. 60% of patients treated with APD in North America also receive at least one exchange during the day. APD is more expensive than CAPD, but is usually cheaper than a transfer to in-centre Haemodialysis.

PD Effectiveness Testing

To see if the exchanges are removing enough waste products such as urea, several tests must be performed regularly. These tests are especially important during the first weeks of dialysis to determine whether the patient is receiving an adequate amount or dose of dialysis.

The peritoneal equilibration test measures how much sugar has been absorbed from a bag of infused dialysis solution and how much urea and creatinine have entered into the solution during the 4-hour exchange.

In the clearance test, samples of used solution drained over a 24-hour period are collected, and a blood sample is obtained during the day when the used solution is collected. The amount of urea in the used solution is compared with the amount in the blood to see how effective the PD schedule is in removing urea from the blood.

From the used solution, urine and blood measurements, the health care team can compute a urea clearance rate called Kt/V and a creatinine clearance rate. The residual clearance of the kidneys is also considered. These measurements will show whether the PD prescription is adequate. If the laboratory results show that the dialysis schedule is not removing enough urea and creatinine, the doctor can change the prescription.