Peritoneal dialysis: an evolving understanding

Since continuous ambulatory peritoneal dialysis (PD) was introduced in 1978 by Popovich and Moncrief, the use of peritoneal dialysis as effective renal replacement therapy has expanded on an international level. Improvements in technology and technique have lessened the incidence of infectious complications, although strategies continue to evolve to improve technical success. As technical challenges have been met, increasing attention has been turned to PD dose. Retrospective studies have strongly suggested that patient outcome is related to the amount of toxin removal. Recently, prospective data confirm that morbidity and mortality are strongly associated with dialysis adequacy. The important contribution of residual renal function to total toxin clearance is now recognized and implies a need to adjust dialysis dose to maintain adequate clearance as residual renal function declines. Reasonable, yet arbitrary, targets for dialysis clearances can now be asserted as Kt/V of 2.0 per week and weekly creatinine clearance of 60 L/wk. These current guidelines indicate a need to individualize dialysis dose to achieve target clearances and improved outcome. Current data also indicate that malnutrition is highly prevalent in the PD population and is associated with poor clinical outcomes, including decreased survival. Deterioration in nutritional status begins before the initiation of dialysis, and it seems that worse nutritional status at the start of dialysis is a strong predicator of poor outcome. These findings suggest that earlier initiation of dialysis, before a significant decline in nutritional status occurs, is warranted to maintain good nutrition and optimize outcome.