Peritoneal dialysis is a method of removing wastes from blood through the peritoneum, the membrane that lines the stomach cavity. Peritoneal dialysis is an alternative to hemodialysis.
A peritoneal dialysis patient has a catheter permanantly implanted in his or her abdomen. A tubing set is connected to the catheter in order to drain fluid from the peritoneal cavity and to infuse new dialysis solution into the cavity. The solution generally consists of dextrose and electrolytes. Osmotic pressure causes dextrose and electrolytes from the dialysis solution to pass through the peritoneal membrane into the patient's body, while excess fluid and waste products pass through the membrane into the solution. This process mimics the function of healthy kidneys. Patients undergoing continuous ambulatory peritoneal dialysis (CAPD) often have two to three liters of solution in the peritoneal cavity at all times, replaced three to four times per day. Peritoneal dialysis solutions are produced with a wide range of dextrose concentrations so that the amount of fluid removed from patients can be adjusted as necessary.
Because peritoneal dialysis is performed daily, usually at home, patients are generally more independent and feel better than hemodialysis patients who must visit a clinic several times per week with waste building up in their bodies between visits. Drawbacks to peritoneal dialysis include "image changes" and logistical difficulties. Having several liters of extra fluid in the abdomen causes a change in the patient's appearance, and the use of dextrose to provide osmotic pressure can cause weight gain. Peritoneal dialysis solutions generally have a pH just above 5 (biological pH is approximately 7.4), so that some pain can be experienced by the patient during infusion. A patient normally receives a month's worth of supplies at a time, and storing several hundred liters of solution can be inconvenient.
As stated above, most peritoneal dialysis solutions have a pH near 5. The reason for this is that these solutions usually undergo terminal sterilization as the last step of the manufacturing process. This method is used in preference to aseptic manufacturing techniques in order to reduce costs. Terminal sterilization usually involves the use of an autoclave to place the product under temperature and pressure conditions severe enough to kill any bacteria present. These conditions are harsh enough that degradation of dextrose can occur unless the solution has a low pH. Manufacturers of peritoneal dialysis solutions are in a race to produce economically viable solutions at biological pH, as well as solutions which use alternatives to dextrose for creating the osmotic pressure needed for dialysis in order to reduce patients' weight gain.