Kidney Dialysis

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When a patient has a mild kidney failure where the serum creatinine is less than 400 umol/L, he does not require renal replacement therapy such as dialysis or renal transplant. This is due to the fact that he still has enough residual renal function to sustain life. However he requires certain medications and dietary restriction to delay damage to the kidney.

When his serum creatinine rises to 900 umol/ L, he requires dialysis or a kidney transplant. Dialysis is a process which allows diffusion of solutes dissolved in blood across a semi- permeable membrane into a another solution and vice versa. This means that it removes waste products through this special membrane and bicarbonate can diffuse across to the blood to neutralize acid. In this way the imbalance in the body can be corrected.

There are two forms of dialysis. They are Haemodialysis and Peritoneal Dialysis.

Haemodialysis

Haemodialysis is a process by which excess waste products and water are removed from the patient's blood which is drawn through a special created vein in the forearm known as arterio-venous (AV) fistula into a dialysis solution. This process require the use of a machine. In haemodialysis, the blood channels through plastic tubing to the dialyses which is a bundle of hollow fibers made from semi-permeable membrane. Here the exchange (diffusion) takes place from blood to the dialysis solution (dialysate) and vice versa. The dialysate has a salt composition similar to blood but without any waste products.

Usually one session takes about 4 hours to complete and patient requires dialysis 3 times a week.

The advantages and disadvantages of haemodialysis

Advantages

Staff performs treatment in the dialysis center.
Regular contact with people in the center.
Three treatments per week.
No external access required.
No equipment/supplies at home.

Disadvantages

Requires travel to a center.
Fixed treatment schedule.
Permanent internal access.
Two needle sticks for each treatment.
Diet and fluid intake restricted.

Peritoneal Dialysis

Peritoneal dialysis is performed by introducing dialysis solution into the peritoneal (abdominal) cavity through a slapstick catheter. The natural membrane lining of the peritoneal cavity is a semi-permeable membrane where waste products and excess water from the body pass through the membrane into the dialysis solution. This solution can be drained out of the abdomen into a bag and be thrown away.

The dialysis solution (dialysate) used is sterile and contains salts and high content of glucose (sugar). The presence of glucose will cause water from the blood stream to be drawn into the peritoneal cavity by means of osmosis. Waste products are removed by diffusion. Each exchange, that is draining of the old solution and replacing it with a fresh solution, takes about 45 minutes.

The advantages and disadvantages of peritoneal dialysis

Advantages