Dialysis is a medical treatment of the blood that artificially replaces the functions of the kidneys. It is used to remove waste and unwanted water from the blood. The removal of waste is known as diffusion, while removal of unwanted water is called ultrafiltration. Both of these processes are naturally undertaken by the kidneys. However, in cases of acute kidney damage (also known as acute renal failure), or the end stage of chronic kidney disease, the kidneys are unable to perform their functions and dialysis is used to keep patients alive and alleviate the symptoms of the disease.

In either case, dialysis is normally a temporary measure, used to prevent damage to other organs while treatment of the underlying causes of acute kidney damage, or while waiting for a kidney transplant. Unlike acute kidney damage, the end stage of chronic renal disease is not usually reversible, so a transplant is usually required; where a transplant is inappropriate, dialysis will have to be undertaken periodically
throughout the remainder of the patient’s life.

Hemodialysis

There are two types of dialysis treatment, hemodialysis and peritoneal dialysis.

Hemodialysis involves insertion of a catheter into a vein and running the patient’s blood through an artificial filtering system to remove wastes and excess water, then returning the blood to the patient’s body. The process requires about three to four hours and in most cases needs to be done once a week. It is the most efficient type of dialysis in terms of time required.

Hemodialysis requires that a vein be enlarged, usually through surgery, before the procedure is undertaken. Although it is possible for hemodialysis to be performed at home given the right equipment, it is not an easy procedure and most patients have it done on an outpatient basis. It is not a procedure to be undertaken by a patient entirely alone, but can be done with the aid of a caregiver provided the patient’s condition is stable.

Peritoneal Dialysis

The other type of dialysis, peritoneal dialysis, makes use of the natural filtering ability of peritoneal membrane (in the patient’s abdomen), aided by a sterile dialysate solution, to filter the blood internally rather than removing it and running it through an artificial kidney.

Peritoneal dialysis is more time-consuming than hemodialysis and usually needs to be done on a daily basis. However, the patient can perform normal activities while the dialysis is going on, which is not the case with hemodialysis. This form of dialysis is easier to do at home than hemodialysis as well.

Neither type of dialysis is as efficient at cleansing the blood as the natural action of a healthy kidney, nor does it replace the other function of the kidneys, which is to produce certain endocrine hormones.

If dialysis is being relied upon to replace kidney functioning, it is often necessary to use dietary therapy and medication to supplement the process.

Dialysis Disequilibrium Syndrome

Dialysis disequilibrium syndrome, or DDS, is a disorder of the central nervous system sometimes resulting from dialysis, most commonly in end-stage chronic renal disease patients rather than those suffering from acute kidney damage.

Dialysis disequilibrium syndrome is a form of cerebral edema caused by water moving into the brain, leading to seizures. Exactly why this happens is not fully understood. It is known that the occurrence of dialysis disequilibrium syndrome is more prevalent the first few times that dialysis is undertaken.

The best treatment for DDS is to avoid the syndrome. For this reason, in the beginning dialysis patients are given shorter treatments.