Adequacy of Peritoneal Dialysis in Children: Consider the Membrane for Optimal Prescription

Abstract

The peritoneal dialysis (PD) prescription should be adequate before being optimal. The peritoneal membrane is a dynamic dialyzer: the surface area and the vascular area both have recruitment capacity. At bedside, prescription is based mainly on tolerance of the prescribed fill volume, and therefore a too-small fill volume is often prescribed. A too-small fill volume may lead to a hyperpermeable exchange, with potentially enhanced morbidity—or even mortality—risks. Better understanding of the peritoneal membrane as a dynamic dialysis surface area allows for an individually adapted prescription, which is especially suitable for children on automated PD. Fill volume should be scaled for body surface area (mL/m2) and, to avoid a hyperpermeable exchange, for a not-too-small amount. Fill volume enhancement should be conducted under clinical control and is best determined by intraperitoneal pressure measurement in centimeters of H2O. In children 2 years of age and older, a peak fill volume of 1400 – 1500 mL/m2 can be prescribed in terms of tolerance, efficiency, and peritoneal membrane recruitment. Dwell times should be determined individually with respect to two opposing parameters: • Short dwell times provide adequate small-solute clearance and maintain the crystalloid osmotic gradient (and, thereby, the ultrafiltration capacity). • Long dwell times enhance phosphate clearance, but can lead to dialysate reabsorption. The new PD fluids (that is, those free of glucose degradation products, with a neutral pH, and not exclusively lactate-buffered) appear to be the best choice both in terms of membrane recruitment and of preservation of peritoneal vascular hyperperfusion.