What is peritoneal membrane transport, and why is it important?
Bidirectional transport of solutes and water occurs across the capillary walls of peritoneal membrane. Solute concentration gradients between the peritoneal capillary blood and the PD fluid are the primary drivers of net transport. However, the intrinsic transport characteristics of the peritoneal membrane capillary network are variable between patients and have a significant impact on patient outcome. Understanding an individual patient’s peritoneal membrane transport type is therefore critical to appropriate tailoring of their PD prescription.
Membrane transport is classified as slow, slow average, fast average, or fast, according to the peritoneal equilibration test (PET), as described in the following sections. In general, patients with fast to fast average membrane transport characteristics should be prescribed shorter dialysis dwell times to enhance fluid and small solute removal. Patients with slow and slow average membrane transport should generally be prescribed longer dwell times.