What is dialysis?
Dialysis is a treatment which replaces the function of the kidneys when a patient’s renal function decreases to an insufficient level.
The kidneys play an essential role in the human body. They are made up of nephrons which filter waste (urine and creatinine) and excess minerals from the blood into the urine. By purifying the blood in this way, the kidneys regulate the body’s level of hydration. When nephrons are destroyed by 90%, renal deficiency requires a dialysis or a kidney transplant.
Types of dialysis
There are two main dialysis techniques:
- Haemodialysis is a process which purifies the blood. It involves the blood passing through a dialysis machine which filters waste from it.
Once cleaned, the blood is returned to the body. In order to obtain a rather quick blood flow, it is necessary to find an easy point of access to the blood. This is what is called a vascular access. This can be an arteriovenous fistula or a catheter (flexible plastic tube). The dialysis machine only purifies the blood a little bit at a time. It’s for this reason that haemodialysis is a long and frequently repeated procedure. The most common number of procedures is three sessions of 4 hours per week. This can be done at home or in a specialised centre.
- Peritoneal dialysis does not require a machine. In fact, it uses the peritoneum cavity as a filter. The peritoneum is the membrane which covers the abdominal wall and surrounds abdominal organs.
Dialysate fluid is put into plastic sterile pockets and placed in the cavity via a catheter, which plays the role of the peritoneal access. After a few hours, the dialysate fluid is saturated and must be changed. The procedure of filling and draining the dialysate can be done in different ways.
Continuous peritoneal ambulatory dialysis (CAPD) is performed manually and daily. It requires four changes per day. Automated peritoneal dialysis (APD) is, as the name implies, automated. Fluid exchanges take place throughout the night and are carried out by a device called a cycler. It is a lot less restrictive than CAPD.