1. What is dialysis?
When kidneys cannot perform their job well, the patient needs an artificial kidney. Dialysis machine is kind of artificial kidney which filters the blood, removes toxins, and adjusts the electrolyte contents of the blood.
2. What types of dialysis are out there?
Important types of dialysis are hemodialysis and peritoneal dialysis. In hemodialysis, patient's blood gets filtered in the dialysis machine through a filter as explained below. In peritoneal dialysis, a catheter is placed in the abdominal cavity and a standard sterile fluid is infused inside the abdominal cavity. Blood gets cleaned through peritoneal membrane which is a natural thin abdominal membrane in every human being. Hemodialysis is more common in the United States, which should be done in the dialysis center most of the time. Peritoneal dialysis can be done by the patient at home.
3. How does hemodialysis work?
When a patient is connected to the dialysis machine, his arterial blood goes out of his body to the dialysis machine which has a filter. Blood passes through one side of the filter and water with standard amount of electrolytes circulates on the other side. Waste substances of the blood pass through the filter and enter the water side. The reason is that concentration of waste products is more in the blood compared to water. This effect is called osmosis.
4. Which patient needs dialysis?
When kidney function is so bad that concentrations of urea and creatinine are very high, patient will need dialysis. These patients usually have lots of acid in their blood, because their kidneys cannot excrete acid which is normally produced every day in the body. They may have high concentration of phosphate and potassium in the blood for the same reason. When kidneys do not work well, urine is not produced and excess fluid accumulates in the body causing high blood pressure and shortness of breath.
5. How does blood get out of body and goes to dialysis machine?
A patient on dialysis either has a catheter in his vein or a fistula. A catheter is considered a temporary way for dialysis. The longer a catheter stays in the vein, the higher is the risk of infection. A more durable and safer way for dialysis is placement of arteriovenous fistula. In this method, one of the arteries of the arm is connected to the vein next to it. When the patient goes to dialysis center, two needles are placed in the arterial and venous sides. Blood gets out from the arterial needle, goes to the machine and gets filtered, then returns to the body through the venous side.
6. Is dialysis a permanent need?
In a patient, with normal kidney function who gets acute kidney failure, the need for dialysis is usually temporary. He may become dialysis independent in a few months. On the other hand, a patient with chronic kidney disease, usually due to longstanding diabetes and hypertension, has irreversible kidney disease and needs long term dialysis.
7. How many times a week a patient needs dialysis?
It is variable and depends on the level of kidney function. In a patient with very poor kidney function, who makes only little amount of urine, dialysis is usually 3 times a week and each session is about 3 hours. Patients who have higher body mass, usually need more time on dialysis. Patients who have good amount of urine output, may need less time on dialysis. A nephrologist will evaluate the patient and makes the decision.
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