Renal Replacement Therapy

Renal Replacement Therapy :

When kidney function is such that life can not be sustained without supplementing kidney function by external help, renal replacement therapy is started. In temporary renal disease (most cases of AKI) this is required for short periods only. Once kidneys recover, RRT is stopped. In permanent kidney disease (End stage Renal Disease) RRT is required through life.

RRT is of 2 types

Renal Transplant

Dialysis either regular intermittent hemodialysis or Continuous Ambulatory Peritoneal Dialysis.

Renal Transplant is the method of choice in all age groups where feasible. All human beings usually have 2 kidneys. However, about 1 in 400 persons is born with one kidney. They can pass through life without difficulty and without realising that they have only one kidney.

Since one fully functioning kidney is enough to sustain life, in renal transplant an extra kidney is placed in the patient of CKD (Chronic kidney disease). This kidney than can maintain life by working almost as patients own kidneys.

Requirements for renal transplant

The person suffering from kidney failure should not have cancers, advanced diseases of heart, lungs, liver etc. If the life expectancy of the person due to the diseases of other organs is a few months only transplant is of little benefit. HIV is no longer an absolute contraindication, and many renal transplants have now been done in patients with Hepatitis B and C positivity. Age of the patient is usually not a bar for transplant.

The second important factor is a donor. The donor can be a cadaver ( in case of brain death a heart beating donor or nowadays in some cases a nonheart beating donor as well.). In the later case kidneys are removed immediately after cessation of heart activity.

The other variety of donors are live donors who have 2 healthy kidneys and wish to donate one of these for the recovery of their near and dear ones.

In India, Transplant of Human Organs Act with its various amendments from time to time, allows donation from near relatives ie parents, grandparents, siblings, children and spouse. All other transplants are called unrelated transplants. Any transactions financial, inducements of any nature etc are forbidden by law. These are morally indefensible and attract severe punishment for this crime.

The donor has to be willing and should be under no pressure to donate his kidneys. He or she should be well informed about the procedure, its various risks, likely outcomes and associated complications both in long and short term.

Donors undergo a series of evaluation for determining fitness for the act of donation. These are then examined by a committee to ensure that the transplants can be performed as per the provisions of the law and necessary care has been taken to ensure safety of the patient.

Dialysis

Dialysis

When the kidneys fail to maintain the body in a healthy state, the condition is called chronic renal failure. In advanced stages of chronic renal failiure, symptoms arise. These are called uremic symptoms and may consist of one or more of the following:-

Weakness, decreased appetite, nausea, vomiting, hiccups, breathlessness, swelling of the body, decreased amount of urine etc. Later on a person may develop fits or increasing drowsiness, unconsciousness, extreme weakness, muscle paralysis etc. Initially these symptoms are mild but later on they do not allow a person to live a normal life and still later they will kill a person unless treated.

The process of taking over of failed kidney functions by treatment is called Renal Replacement Therapy (RRT). This mainly comprises of Dialysis and Renal Transplant.

Dialysis is the process through which the accumulated waste products are removed. It also removes extra water salt, potassium, acid, phosphorus and molecules of middle size.  Thus it attempts to return the body to a healthy state.

Dialysis is mainly of two types:- Hemodialysis and Peritoneal dialysis.

Hemodialysis

In this a membrane called dialysis membrane is used as a filter. It is folded many times over to increase its area to about .5 sq meters to 2 sq meters (for children and adults of various sizes). This membrane allows only small molecules to move from one side to the other.

Blood flows on one side of the membrane and dial sate fluid flows on the other. The dialysate fluid is produced in the dialysis machine by diluting commercial concentrates. The composition of the dialysate is similar to Blood without cells, proteins, fats and other larger molecules.

Smaller molecules present in high concentration in blood and dialysate move across because of difference in concentration (called electrochemical gradient) from a higher concentration to lower concentration. Pressure can be applied across the membrane to create pressure to push water and salt across as well.