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	Alternative to glucose		Icodextrin in practice
	Allergic reactions		Plasma sodium
	BP control and fluid balance		Glucose stability/near-patient glucose testing
	Long-term accumulation/toxicity issues		Other maltose-containing medicines

Continuous ambulatory peritoneal dialysis (CAPD) was first described one-quarter of a century ago and is now firmly established in some parts of the world as the main form of renal replacement therapy. But, however good the initial technique, 10-year technique survival for PD is much inferior to that of haemodialysis (HD).

Long-term studies from the USA, Italy, Australia and UK report that only 0.4 to 3% of patients are still on this modality at 10 years compared with 40 to 80% of HD patients. Of specific patient populations studied, the high transporters have poor long-term survival and increased mortality on peritoneal dialysis.

The main reasons for failure are:

		peritonitis;
		ultrafiltration (UF) failure;
		access problems; and
		patient or family fatigue

To allow for effective water ultrafiltration during CAPD, conventional peritoneal dialysis fluids (PDFs) contain glucose as the osmotic agent in concentrations of 1.36 to 4.25 g/L. Glucose concentrations used in PD solutions (75 to 214 mmol/L) are 15 times to 40 times physiological levels.

Problems associated with the use of glucose include:

		a short duration of effective ultrafiltration, particularly in high transporters;.
		potential for disruption of the peritoneal membrane;
		impairment of peritoneal cellular defence mechanisms; and
		adverse metabolic and nutritional consequences of the daily absorption of 150 to 300 g glucose, such as hyperlipidaemia and body fat accumulation.

Increasing evidence suggests, however, that the potentially deleterious effects of glucose-based PDFs on the peritoneum may be related, not only to high glucose concentrations per se, but also to the formation of glucose degradation products (GDPs) and the subsequent generation of advanced glycation end-products (AGEs). These may lead to long-term, peritoneal-membrane damage, prejudicing technique survival.

Alternative to glucose

Icodextrin (ICO; Baxter Healthcare, Blaby, United Kingdom), a starch-derived glucose polymer that is metabolised to maltose, has been developed as an alternative to glucose in an attempt to lessen these adverse effects and to prolong time on dialysis.

A 7.5% icodextrin-based dialysis solution has an osmolality of 284 mOsm/kg and a pH of 5.3. Icodextrin has a “colloid-induced” osmotic convective transport as opposed to the “crystalloid osmosis” of glucose-based solutions. Icodextrin solution provides sustained ultrafiltration over long dwell times of eight to 12 hours in CAPD and up to 16 hours in automated peritoneal dialysis.

So, potentially, the iso-osmolar icodextrin solution should be less damaging to the peritoneum and to local host defence compared with hyperosmolar glucose solutions. Additionally, owing to the effective UF period, icodextrin can be considered a suitable alternative to glucose-based solutions in the treatment of patients with ultrafiltration failure. And the GDP content of icodextrin is very low compared with that of glucose-containing solutions, yielding a significant reduction in in vitro cell cytotoxicity, glycation of proteins, Amadori-adduct formation, and AGE formation.

Icodextrin in practice

Before using icodextrin, it is important to examine the composition of medications, and to question their applicability and safety in different patient populations.

Allergic reactions

Rare cases of allergic reactions to icodextrin dialysis, all characterised by the occurrence of rash, have been reported before and after its general release and all involved exfoliation or blistering of variable severity. Dextran has been implicated before as causing this. Additionally, a worsening of psoriasis has been described.