In the recent 2001/02 budget, the Federal Government announced that it would increase funding to aid in the provision of more kidney dialysis machines to assist those affected by kidney disease. Jennifer Paterson investigates your kidneys, and what happens when they fail.

What do your kidneys do?

A healthy kidney is basically a filtering system, made up of about a million filtering units called nephrons. Most people have two kidneys, located at the back of the body, behind the lower ribs.

As blood passes through the kidneys, it is "cleaned" and the body's waste products and excess fluid removed.

These waste products, along with excess fluid, are sent through the ureters to the bladder. They then pass out of the body through your urine.

Healthy kidneys also balance the chemicals in your blood, and produce hormones, which control blood pressure and maintain healthy blood cells and bones.

Kidney Failure

Kidney specialist, Dr David Waugh, comments that kidney failure occurs gradually, and 80 to 90 percent of symptoms are "non specific, things like lack of energy, lack of appetite, vomiting, cold intolerance, itchy skin and poor sleep. Sleep is often affected because kidney failure will have a toxic affect on the brain."

He adds that "there are a number of causes of kidney failure, but in quite a lot of people the cause is never found. The most common causes are diabetes, high blood pressure and a painless inflammation of the kidneys called glomerulonephritis."

Other common causes include an inherited inflammation of cysts in the kidneys, (polycystic kidney disease); repeated kidney infections or kidney infections (pyelonephritis) in childhood; and obstruction to the urine flow.

What happens when your kidneys fail?

If kidneys are damaged, they may carry on producing urine, but become less efficient at removing waste products from the blood. Instead they become less efficient at removing waste products from the blood.

At the same time as this occurs, without the hormones that a healthy kidney would produce, the bone marrow becomes less efficient at producing red blood cells - and anemia develops.

For some patients, this can be a gradual process, and cause a wide range of symptoms, so they may not actually realise the effect the symptoms are having until they start to feel better with treatment.

Treatment

Dr Waugh comments that it is possible to 'replace' kidney function, due to failure, with dialysis which is "an artificial way of getting rid of toxins". Not all patients will require dialysis, blood tests will determine the need to start the process and this can sometimes be years after initial diagnosis.

There are two kinds of kidney dialysis - - haemodialysis, where the blood is cleaned outside the body via a machine, and Peritoneal dialysis, where the cleaning is done inside the body.

Haemodialysis

This form of dialysis removes waste products from the blood by passing it out of the body, through a filtering system and returning it, cleaned, to the body.

While in the filtering system, the blood flows through tubes made of a membrane that allows the waste products (which are much smaller than blood cells) to pass out through it.

The waste products pass through the membrane into a dialysis solution (dialysate), then out of the machine. The "clean" blood is carried on through and returned safely to the body.

This happens over and over again throughout the dialysis session. Each time the "clean" blood is returned to the body, it picks up more waste products from the cells it circulates through, and brings these newly-collected toxins back to the dialyser to be removed.

Fresh dialysate is passed through continuously, to make the rate of the cleaning process as fast as possible.

As well as cleaning the blood, the dialysis machine also removes excess water. This part of the process is called ultrafiltration which can be done separately without dialysis.

Dr Waugh comments that this type of procedure will need to be carried out three times per week, and each session will take about 5 hours, "generally resulting in an all-day time commitment for the patient."

Peritoneal dialysis

With this method, instead of being cleaned by an artificial membrane outside the body, the blood is cleaned inside the body, through the Peritoneum. This is the thin membrane that surrounds the outside of the organs in the abdomen.

The peritoneum allows waste products to pass through it and is very rich in small blood vessels. By running a dialysis fluid into the peritoneal cavity, through a tube called a Tenckhoff Catheter - and then out again - waste can be filtered from the blood.

CAPD - which stands for Continuous Ambulatory Peritoneal Dialysis - happens throughout the day, at home or at work, while the person goes about his or her daily life. Between 1.5 and 3 litres of fluid is run in four times a day, exchanging for the fluid from the previous exchange. This takes about 30-40 minutes.

APD - Automated Peritoneal Dialysis - in which the dialysate solution is changed by a machine, at night, while you are asleep. The machine will exchange 8-12 litres over 8-10 hours and then leave 1-2 litres to dwell during the day.

Peritoneal dialysis is designed so that patients are able to conduct their own dialysis at home, once trained by a health professional. Dr Waugh comments that this type of dialysis is often used by the " elderly and children but is generally not suitable for those who are overweight or have a weak heart."