Types of treatments
When severe loss of kidney function occurs, the kidneys function must be replaced. For many people a successful kidney transplant is the best way to do this. However, this treatment option is not possible for all patients and some patients have to wait a long time to receive a kidney transplant.
How does dialysis work?
Dialysis removes waste and fluids from your body that your kidneys are not able to remove. Dialysis also aims to keep your body in balance by correcting the levels of
various toxic substances in your blood. Without dialysis, all patients with kidney failure would die from the build-up of toxins in the bloodstream.
Principals of dialysis
There are two main types of dialysis: haemodialysis and peritoneal dialysis. Whichever treatment is chosen the aims of dialysis are very similar. Dialysis is designed to replace several functions of the kidney. The therapy must: remove waste products, remove excess fluid and balance the amount of chemicals (electrolytes) and other substances in your body. Effective dialysis requires: a semi permeable membrane, blood supply, dialysis fluid and a method of removing excess fluid.
Semi permeable membrane
In dialysis a semi permeable membrane separates the blood from the dialysis fluid. This membrane allows some substances to pass through, but not others. It allows waste products, water, electrolytes and other substances to be removed from the blood into the dialysis fluid (and sometimes in the other direction) by a process called diffusion. The movement of waste products and other substances is dependent on the membranes permeability, the size and structure of the various substances, the dialysis fluid makeup, and the blood supply to the membrane.
The better the blood supply to the membrane the more efficient the dialysis treatment. In haemodialysis blood supply can be controlled by the dialysis machine whereas in peritoneal dialysis blood supply is dependent on internal body make up.
In both dialysis modes the dialysis fluid enables waste products to be removed from the blood. In addition to this, it contains a range of substances which help to correct imbalances that occur as a result of kidney failure.
Fluid removal is achieved by very different processes in haemodialysis versus peritoneal dialysis. In haemodialysis the dialysis machine uses pressure to pull fluid across the membrane from the blood and into the dialysis fluid. In Peritoneal dialysis glucose is used in the dialysis fluid, this has the effect of encouraging fluid to move out of the blood and into the dialysis fluid.
Aim of dialysis
Whichever dialysis treatment is used the aim is to: remove waste products, remove excess fluid, correct electrolyte imbalances and to correct the pH of the body.
Peritoneal dialysis (PD) is performed at home. The therapy can either be performed over night for 8-10 hours or in 4 to 5 short procedures during the day, which takes 1 to 2 hours per day to complete. However it is carried out peritoneal dialysis gives flexibility and can be fitted around work, family and social commitments. Usually patients come to the hospital outpatient clinic every 3-6 months for follow up. Many people on PD are able to enjoy a normal diet without too many restrictions, but may need to moderate their intake of certain types of food.
Haemodialysis (HD) is usually performed in hospital or in dialysis clinics three or possibly four or more times per week. The procedure usually takes a minimum of 4 hours, but may take up to 6 hours. On top of the time for treatment, the dialysis day also involves travel to and from hospital or clinic, waiting for treatment to start, and waiting for transport home. In total, haemodialysis in hospital can take many hours, which has an impact on work, family and other commitments. Most people on haemodialysis must also restrict their diet and fluid intake.
Sometimes, other options for haemodialysis are available. These include self-care or home dialysis and also daily or nocturnal dialysis. These options aim to increase flexibility, allow a normal diet without too many restrictions, and improve quality of life for a patient on dialysis.
Every type of dialysis has its pros and cons and not all may be available at your dialysis clinic. By learning as much as you can about the types of dialysis, you will be able to make the best decision for yourself.