What Is Dialysis? What Is Kidney Dialysis?

Dialysis is the artificial process of eliminating waste (diffusion) and unwanted water (ultrafiltration) from the blood. Our kidneys do this naturally. Some people, however, may have failed or damaged kidneys which cannot carry out the function properly - they may need dialysis.

In other words, dialysis is the artificial replacement for lost kidney function (renal replacement therapy).

Dialysis may be used for patients who have become ill and have acute kidney failure (temporary loss of kidney function), or for fairly stable patients who have permanently lost kidney function (stage 5 chronic kidney disease).

When we are healthy our kidneys regulate our body levels of water and minerals, and remove waste. The kidneys also produce erythropoietin and 1,25-dihydroxycholecalciferol (calcitriol) as part of the endocrine system. Dialysis does not correct the endocrine functions of failed kidneys - it only replaces some kidney functions, such as waste removal and fluid removal.

Dialysis and altitude - A study found that death rates for dialysis patients are 10%-15% lower for those whose homes are higher than 4,000 feet, compared to those who live at sea level.

Some countries, such as the UK, are predicting a doubling of the number of patients on dialysis machine.
Why is dialysis necessary?

Approximately 1,500 liters of blood are filtered by a healthy person's kidneys each day. We could not live if waste products were not removed from our kidneys. People whose kidneys either do not work properly or not at all experience a buildup of waste in their blood. Without dialysis the amount of waste products in the blood would increase and eventually reach levels that would cause coma and death.

Dialysis is also used to rapidly remove toxins or drugs from the blood.
There are two main types of dialysis - hemodialysis and peritoneal dialysis

What type of dialysis a patient should have really does depend on each individual case. Studies have indicated clearly that for kidney disease patients who need to undergo dialysis, one type of treatment is not best for all.

What is hemodialysis?

The blood circulates outside the body of the patient - it goes through a machine that has special filters. The blood comes out of the patient through a catheter (a flexible tube) that is inserted into the vein. The filters do what the kidney's do; they filter out the waste products from the blood. The filtered blood then returns to the patient via another catheter. The patient is, in effect, connected to a kind of artificial kidney.