Peritoneal dialysis

Peritoneal dialysis (PD) is a home-based renal replacement therapy for patients with end-stage kidney disease, offering a degree of autonomy and flexibility of lifestyle. After the placement of a catheter into the peritoneal cavity under either general or local anaesthetic, the patient is instructed how to perform dialysis exchanges during which 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. On CAPD the standard approach is to perform four exchanges during the 24-hour period using 2 litres of dialysate on each occasion, although the prescription can be varied according to individual requirements. With APD the dialysis machine performs repeated exchanges overnight and the patient may have additional daytime exchanges if necessary. Water is removed via the osmotic effect of the glucose in the dialysate, although other osmotic agents can also be used, including icodextrin, a glucose polymer, and amino acids. The most common complication of the technique 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. The patient must either be capable of performing the technique him/herself or have a carer who is willing and able to do so. Over the last few years in the UK, APD performed by healthcare assistants has become available for those who are unable to do the dialysis themselves.