Hemodialysis
Hemodialysis is a therapy that filters waste, removes extra fluid and balances electrolytes (sodium, potassium, bicarbonate, chloride, calcium, magnesium and phosphate).
In hemodialysis, blood is removed from the body and filtered through a man-made membrane called a dialyzer, or artificial kidney, and then the filtered blood is returned to the body.
The average person has about 5 litres of blood; during dialysis only 200ml (about two cups) is outside of the body at a time.
To perform hemodialysis there needs to be an access created to get the blood from the body to the dialyzer and back to the body.
The dialyzer is the key to hemodialysis. The dialyzer is called the artificial kidney because it filters the blood — a job the kidneys used to do.
The dialyzer is a hollow plastic tube about a foot long and three inches in diameter that contains many tiny filters.
There are two sections in the dialyzer; the section for dialysate and the section for the blood.
The two sections are divided by a semipermeable membrane so that they don’t mix together.
A semipermeable membrane has microscopic holes that allow only some substances to cross the membrane.
Because it is semipermeable, the membrane allows water and waste to pass through, but does not allow blood cells to pass through.