Rethinking the peritoneal dialysis prescription: results of recent studies.

Peritoneal dialysis treats uraemia in a way different from hemodialysis. The continuous nature of peritoneal dialysis optimises the removal of uraemic toxins of larger molecular weight, the so-called 'middle molecules'. Initially, there was an appreciation of the efficacy of this kind of slow, continuous dialysis. However, with the growing emphasis on adequacy as defined by small solute kinetics, blood purification by peritoneal dialysis was considered to be inferior to that performed with hemodialysis. With the subsequent publication of studies showing a lack of correlation of small solute clearance parameters with outcome in peritoneal dialysis, attention is again being paid to the benefits of continuous dialysis that treats renal failure in a way not quantifiable by small solute kinetics.