PERITONEAL DIALYSIS MACHINE

Typical Number in Hospital: 3

Cost Bands: 4

References: 3,4

Where the function of the kidneys is impaired or absent some replacement of the lost function can be achieved by a process of dialysis, in which small molecular weight toxins (e.g. urea) are removed from the body by diffusion through a semipermeable membrane into a special dialysing fluid.

In haemodialysis, blood is removed from the body and passed over a dialysing membrane through which the toxins diffuse. In peritoneal dialysis, the dialysing fluid is passed through a surgically inserted tube, into a space between the two membranes of the peritoneum. The peritoneal membrane envelops most of the organs in the abdomen.

A peritoneal dialysis machine controls the passage of the dialysing fluid into the peritoneal cavity where the diffusion exchange takes place. It may also employ a weighing transducer to monitor the quantity of fluid infused. Some machines prepare the dialysing solution from a sterile concentrate, and water produced in a reverse osmosis column. After a period of time the fluid is withdrawn and a new solution infused. The machine itself is a set of valves, pumps and timers which control this process. Such devices are used in intensive care to remove natural toxins or drugs, and are also used in cases of renal failure.

Peritoneal dialysis is now widely used without automatic equipment, using a simple collapsible bag which the patient operates himself at home. This technique is called continuous ambulatory peritoneal dialysis (CAPD), and apart from the lessened restriction on the patient's lifestyle, it also reduces the risk of infection due to repeated connections of apparatus. Peritoneal dialysis, since it takes place inside the body, requires a much higher quality of dialysing fluid.