Definition & Overview

The kidneys, which are a part of the body's renal system, remove waste products and excrete them in the form of urine. When the kidneys fail, waste can build up in the body and cause certain death. Dialysis is a procedure that takes over the functions of the kidneys in the case of a kidney failure, which is to remove the waste products.

Kidney failure is often caused by chronic kidney disease (CKD), which is categorized into five stages. Stage 1 is the early stage of the disease, while stage 5 CKD is when the patient requires a kidney transplant or dialysis.

The stages of CKD are based on the glomerular filtration rate (GFR), which is a measure of the percentage of kidney function. A CKD with a GFR that is equal or greater than 90 is stage 1, while a GFR that is less than 15 is stage 5. According to the guidelines of the National Kidney Foundation, dialysis should start when GFR drops down to a level of 6.

Who should undergo and expected results

Dialysis is recommended for patients with stage 5 CKD, which means that the kidneys can no longer function normally and that uremia (waste in the blood) is present. However, it's important to note that dialysis is not a form of treatment, which means that the procedure cannot cure the disease. The only cure for the condition is a kidney transplant procedure.

The result of failing kidneys is the build up of uremia in the blood stream. When the amount of uremia reaches a certain level, the patient begins to feel sick. If the level gets too high, it is likely that the patient will die.

In order to decide when the patient requires dialysis, doctors measure that creatinine and blood urea nitrogen (BUN) levels. Higher levels indicate that the kidneys are failing to function normally.

Once the doctor recommends that the patient undergo kidney dialysis, it is likely that the procedure will be required for the rest of the patient's life, unless he or she receives a kidney transplant. While on dialysis, the life expectancy is 5 to 10 years, but there are cases when patients have lived normal lives with dialysis for over 30 years. However, statistics shows that 1 in 4 patients who undergo dialysis will not survive for a year.

How the procedure works

There are two types of dialysis: peritoneal dialysis and hemodialysis. In a peritoneal dialysis procedure, the patient's own tissues in the abdominal cavity are used to filter the body's waste products. The procedure involves placing a dialysis catheter into the abdominal cavity. A special fluid is delivered through the catheter to wash the abdominal cavity and intestines. The intestinal walls will therefore act as a filter between the fluid and bloodstream.

There are 2 types of peritoneal dialysis: continuous ambulatory peritoneal dialysis (CAPD) and automated peritoneal dialysis (APD). CAPD allows the patient to be mobile and function normally. The procedure can be performed while the patient is at work, at home, or just about anywhere. The catheter that is inserted into the abdominal cavity is attached to a bag on the other end. When required, the patient places dialysate into the bag, which is then transferred to the abdominal cavity through the catheter. After about four to five hours, the dialysate is drained back into the bag and thrown away.

An APD procedure, on the other hand, requires the use of a machine called a cycler. The concept is similar to CAPD, with the exception that the cycler performs feeds and drains the dialysate automatically for a number of cycles with each cycle lasting around 1.5 hours. APD is usually performed at night while the patient is sleeping. Meanwhile, a hemodialysis procedure requires the use of a dialysis machine, also referred to as a dialysis membrane. The patient's blood is directed into the machine, which then filters it and returns the cleansed blood back into the patient's body.

Patients who require dialysis need to have easy access to the procedure. Those on hemodialysis will need to undergo the procedure three times a week for 3 to 5 hours per session. Those on CAPD or APD won't need to report to a hospital or dialysis center as frequently because the procedure can be performed at any time.

Possible risks and complications

Both hemodialysis and peritoneal dialysis have associated risks and possible complications. Patients who undergo hemodialysis may experience hypotension, itching, muscle cramps, anemia, sleep problems, bone diseases, fluid overload, hypertension, hyperkalemia, pericarditis, depression, amyloidosis, and access site complications.

On the other hand, patients who undergo peritoneal dialysis may experience infections, weight gain, and weakening of the abdominal muscles.

How to Know if the procedure is working

Dialysis is the only option for patients with CKD. The procedure can prolong patients' lives and enable them to live almost normal lives, as long as the dialysis is providing the desired results.

The ultimate goal of dialysis is to remove waste products from the patient's body, without lowering the levels of necessary minerals. To know if dialysis is working properly, the patient will need to undergo blood tests at regular intervals. Doctors will pay close attention to the blood urea nitrogen (BUN) levels to ensure that these are not rising. They will also check the levels of sodium, calcium, potassium, and bicarbonate.

How to improve the chances of success of the procedure

Dialysis may not cure CKD, but it is the best option until the patient receives a kidney transplant. Until that happens, the patient will need to ensure that the chances of success of the procedure remain high. They can do this by making lifestyle and diet changes.

Patients on dialysis are often recommended to reduce the intake of salt (sodium). They will also be asked to limit the consumption of foods that are rich in phosphorus and potassium. A high-protein diet is often recommended.


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  • Mitch WE. Chronic kidney disease. In: Goldman L, Schafer AI, eds. Goldman's Cecil Medicine. 24th ed. Philadelphia, PA: Elsevier Saunders; 2012:chap 132.
  • Tolkoff-Rubin N. Treatment of irreversible renal failure. In: Goldman L, Schafer AI, eds. Goldman's Cecil Medicine. 24th ed. Philadelphia, PA: Elsevier Saunders; 2012:chap 133.
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