Evaluation of peritoneal membrane pore models.

Pore models of peritoneal fluid and solute transport are reviewed and critiqued. Although several pore models of the peritoneal membrane have been previously formulated, a model containing three distinct pore sizes is required to accurately simulate both the molecular size dependence of solute transport and the time dependence of fluid transport during peritoneal dialysis in man. Nevertheless, certain observations from peritoneal dialysis experiments using animals do not agree with predictions from the three-pore model. These discrepancies suggest that the three-pore model of peritoneal transport based exclusively on capillary physiology is incomplete. Moreover, our inability to accurately estimate peritoneal reflection coefficients for small osmotic solutes questions whether lymph flow rates from the peritoneal cavity calculated using the three-pore model are reliable. Further experimental and theoretical studies are needed to obtain a better understanding of peritoneal transport physiology.