There are two main types of dialysis: haemodialysis and peritoneal dialysis. (These are also called different modalities.) Both types remove waste and water from the blood.
This section gives an introduction to these two types of dialysis, so you understand the benefits and risks of each type, and the surgery that is needed. In many cases, you will be able to decide the best type of dialysis for your child.
What to consider
The types of dialysis differ in important ways, and there are many things to consider as you and your child decide on the most suitable type. These include:
- where the dialysis takes place – in the hospital or at home
- whether you and/or other family members or carers are able to carry out the dialysis
- whether your house or flat is suited for dialysis at home, and whether any modifications are needed
- how often your child needs a dialysis session
- how long each dialysis session lasts
- your child’s age
- how near you are to your dialysis unit
- the risks and side-effects.
Haemodialysis
In haemodialysis, a machine with an ‘artificial kidney’ filters the blood. Blood is pumped out of the body through tubes and into the artificial kidney, and the cleaned blood is returned to the body. This form of dialysis is often shortened to HD.
What happens in haemodialysis?
For each dialysis session, the patient is connected to the haemodialysis machine, either through a long plastic tube that has been inserted into his or her body (the central venous line, or line) or using a needle or needles placed into blood vessels that have been joined up (a fistula).
- The machine pumps blood out of the body through tubes and into a dialyser or artificial kidney. This sits outside the machine.
- The machine pumps special fluid called dialysate into the dialyser.
- Waste products, salts and excess water are filtered out of the blood and into the dialysate.
- The cleaned blood is then pumped back into the body.
How often is haemodialysis needed and how long does it take?
Each dialysis session usually lasts 3–4 hours and is normally done during the day. Most children have sessions three times a week, though they may need it more often. Although children are connected to the machine, they can read, play and, importantly, spend time doing school work with a teacher.
Where does haemodialysis take place?
- Hospital haemodialysis – most of the time haemodialysis takes place in a special area in the paediatric renal unit in a hospital. This means your child may need to travel some distance.
- Home haemodialysis – some children have haemodialysis in their home. This depends on many factors, including the availability of this service, whether your home can accommodate the equipment, how far you live from the unit, the time needed to train you to run haemodialysis, the time your child is likely to be on dialysis, and his or her age and size.
Peritoneal dialysis
In peritoneal dialysis, the peritoneum, which is the lining of the abdomen (tummy), filters the blood.
What happens in peritoneal dialysis?
For each dialysis session, the patient is connected to the peritoneal dialysis equipment and special fluid called dialysate is passed into and out of the body. Each time the dialysate is passed into and then removed from the body is called an exchange.
Each exchange consists of three phases: a fill, a dwell and a drain.
- During the fill phase, the dialysate flows from a bag through a catheter (a long, thin tube that has been placed before dialysis starts) in the abdomen. It passes into the peritoneal cavity, the area inside the abdomen (tummy).
- The dialysate stays in the abdomen for a set period of time. This is called the dwell.
- During the dwell, the waste products, extra water and salt filter out of the blood and into the dialysate. This happens because of a process called diffusion.
- At the end of the dialysis session, the fluid with the waste products, extra water and salt is drained out of the abdomen into another bag, and then thrown away. This is the drain phase.
Types of peritoneal dialysis
There are two types of peritoneal dialysis, which affect how long and how often the exchanges take place.
- Continuous ambulatory peritoneal dialysis (CAPD). Exchanges usually take place four times a day. The dialysate is in the abdomen for about 4 hours each time. Each exchange needs to be done by you or another responsible person.
- Automated peritoneal dialysis (APD) or continuous cycling peritoneal dialysis (CCPD). Exchanges take place overnight – usually for about 9-12 hours. A machine, which can sit next to the bed, drains fluid into and out of the abdomen. The machine works automatically and you do not need to monitor it once it is up and running.
Where does peritoneal dialysis take place?
Most of the time, peritoneal dialysis is done at home. It can also be done in other places, such as school or other family members’ homes.
More about peritoneal dialysis
Changing dialysis
It may be possible – or sometimes necessary – to change the type of dialysis your child has. This may depend on your child’s health and complications of dialysis, how he or she is responding to dialysis, or your family’s situation. Speak with your child’s healthcare team.