A hemodialysis machine works by using a special filter called a dialyzer, which acts like an artificial kidney to clean and remove toxins from the blood, according to the National Kidney Foundation. The dialyzer consists of two parts separated by a thin membrane. One part of the filter is for collecting the blood, while the other part contains a fluid called dialysate for cleansing the blood.
A patient needs dialysis when the kidneys are no longer able to adequately remove enough waste and fluid from the body, notes the National Kidney Foundation. This normally occurs when there is approximately 10 to 15 percent remaining kidney function. A patient requiring dialysis may experience symptoms such as nausea, swelling, fatigue and vomiting, though this is not always the case. A doctor assesses when and if a patient requires dialysis.
Before a patient can receive dialysis, a doctor performs minor surgery to provide access to the blood vessels, explains the National Kidney Foundation. Dialysis then takes place in either a dialysis center or the patient’s home. During the dialysis process, blood is passed through the membrane in the dialyzer to remove waste products such as creatinine, urea, potassium and extra fluid. Blood cells and proteins remain in the part of the filter containing the blood, because they are too large to pass through the membrane.