Ultrafiltration in peritoneal dialysis

There is a clinical requirement to remove excess body water, electrolytes, and other uremic toxins on a regular basis from patients with end-stage renal failure. During extracorporeal artificial kidney treatment, fluid is removed by simply applying a difference in hydrostatic or hydraulic pressure across the synthetic membrane. This approach is impractical during peritoneal dialysis; instead, fluid is removed from the patient by creating a difference in osmotic pressure between dialysis solution and blood. Thus, fluid removal during peritoneal dialysis is primarily by osmosis and is commonly referred to as osmotic ultrafiltration (or simply ultrafiltration) because of the similarities between transmembrane fluid movement by osmosis and ultrafiltration [1]. We will focus in this chapter on describing both the driving forces that move fluid across the peritoneum and the rate of solute transport that accompanies this transperitoneal fluid movement.