Peritoneal dialysis

Peritoneal dialysis (PD) is a home-based renal replacement therapy for patients with end-stage kidney disease, offering patients some degree of autonomy and flexibility of lifestyle. After the placement of a catheter into the peritoneal cavity the patient is instructed how to perform dialysis exchanges where dialysate is instilled into the peritoneal cavity. These exchanges can either be performed manually (continuous ambulatory or CAPD), or using a machine (automated or APD). During the dialysis exchange small solutes (such as urea, potassium and creatinine) diffuse from the circulation into the dialysate and are removed when the effluent is drained out. In CAPD, the standard approach is to perform 4 exchanges during the 24-hour period using 2 litres of dialysate on each occasion, although the prescription will vary according to individual requirements. With APD a number of exchanges are performed by the dialysis machine overnight and the patient may have additional daytime bags if necessary. Water is removed via the osmotic effect of glucose in the dialysate, although other osmotic agents can also be used, including icodextrin, a glucose polymer, and amino acids. The most common complication is peritonitis, but other problems can include mechanical difficulties with the catheter, or insufficient removal of water or solute. Advantages of peritoneal dialysis over haemodialysis include the preservation of vascular access sites, reduced risk of transmission of blood-borne infection and possibly better preservation of residual renal function.