When Does a Person Need Dialysis?

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Dialysis is the process of removing waste and excess fluid from the blood.  This process is typically handled by the kidney.  Patients who have suffered kidney damage or kidney failure lose some of this functionality.  A patient will typically need dialysis when waste products in the body become too high and they start to cause damage.  These waste products build up slowly and dialysis can help maintain safe levels.  There are several chemical levels in the blood that doctors measure to determine if you need dialysis.  Two of these are the blood urea nitrogen (BUN) level and the creatinine level.  When these levels rise, they indicate decreased functionality of the kidneys to clean waste products from the body.

Creatinine Clearance Test Shows When You Need Dialysis

Some doctors use a urine test called the “creatinine clearance” to measure kidney function.  A patient saves their urine in a container for a full day.  The waste products in the blood and urine are estimated by measuring the creatinine.  They are then compared to see how well the kidney is removing the wastes and depositing them into the urine.  Through this comparison doctors have a good idea of how well the kidneys are working.  The result is called the creatinine clearance.  When creatinine clearance falls below 10-12 cc/minute, the patient is not doing well and may need dialysis.

Calculating creatine clearance to see if patients need dialysis

The doctor uses other indicators of the patient’s status to decide about the need for dialysis. If the patient is experiencing a major inability to rid the body of excess water, or is complaining of problems with the heart, lungs, or stomach, or difficulties with taste or sensation in their legs, dialysis may be indicated even though the creatinine clearance has not fallen to the 10-12 cc/minute level.

What types of dialysis are there?

There are two main types of dialysis: “hemodialysis” and “peritoneal dialysis.” Hemodialysis uses a special type of filter to remove excess waste products and water from the body. Peritoneal dialysis uses a fluid that is placed into the patient’s stomach cavity through a special plastic tube to remove excess waste products and fluid from the body.

In Home Peritoneal Dialysis Treatment

In Home Peritoneal Dialysis Treatment
Photo by BAXTER CZECH

Peritoneal Dialysis

Peritoneal dialysis uses the patients own body tissues inside of the belly (abdominal cavity) to act as the filter. The intestines lie in the abdominal cavity, the space between the abdominal wall and the spine. A plastic tube called a “dialysis catheter” is placed through the abdominal wall into the abdominal cavity. A special fluid is then flushed into the abdominal cavity and washes around the intestines. The intestinal walls act as a filter between this fluid and the blood stream. By using different types of solutions, waste products and excess water can be removed from the body through this process.

Hemodialysis

During hemodialysis, blood passes from the patient’s body through a filter in the dialysis machine, called a “dialysis membrane.” For this procedure, the patient has a specialized plastic tube placed between an artery and a vein in the arm or leg (called a “gortex graft”). Sometimes, a direct connection is made between an artery and a vein in the arm. This procedure is called a “Cimino fistula.” Needles are then placed in the graft or fistula, and blood passes to the dialysis machine, through the filter, and back to the patient. In the dialysis machine, a solution on the other side of the filter receives the waste products from the patient.