A peritoneal dialysis system includes a cycler configured to pump peritoneal dialysis fluid and a disposable set configured to receive the peritoneal dialysis fluid pumped by the cycler. The disposable set includes a filter having a fresh peritoneal dialysis fluid pathway and a membrane located along the fresh peritoneal dialysis fluid pathway and configured to filter the peritoneal dialysis fluid. The filter also includes a grid housing comprising a plurality of baffles configured to separate filtered fresh peritoneal dialysis fluid that has flowed through the membrane into plural fluid channels that form an interior region of the fresh peritoneal dialysis fluid pathway.

A pump device includes a supply chamber having a supply-side accommodation part; a drain chamber having a drain-side accommodation part; dividing membranes each being a flexible member that closes a corresponding one of the supply-side accommodation part and the drain-side accommodation part, the dividing membranes displaceable relative to the supply-side accommodation part and the drain-side accommodation part to cause dialysate to be suctioned into and discharged from the supply-side accommodation part through a liquid-supply-side connection port and cause drain liquid to be suctioned into and discharged from the drain-side accommodation part through a liquid-drain-side connection port; and a pump body from which the supply chamber or the drain chamber is detachable and attachable with the supply-side accommodation part or the drain-side accommodation part being closed by the corresponding dividing membrane, the pump body including a piston to move with activation of a motor and to displace the dividing membranes.

This invention relates to a dialysis apparatus which ultra-filters blood and to a related method of ultra-filtering blood ex-vivo. More preferably the invention relates to haemodiafiltration using protein-losing membranes and a secondary ultrafiltration and partial re-infusion of haemodiafiltrate for increasing extraction of middle molecules and protein bound uraemic toxins and reducing albumin loss.