Dialysis system and method for cassette-based pumping and valving

A peritoneal dialysis system comprising:

• a disposable cassette including a flexible sheet defining a pumping portion of a pump chamber;
• a pump actuator;
• a piston head moved by the pump actuator;
• a disposable cassette interface for interfacing with the disposable cassette, the disposable cassette interface including a pump opening, the piston head moveable out of and retractable into the pump opening to move the pumping portion of the flexible sheet of the disposable cassette, the piston head moving within a vacuum chamber, the vacuum chamber enabling a vacuum to be pulled around the piston head to the flexible sheet of the disposable cassette;
• and
• a plate through which the pump actuator extends towards the pump opening of the disposable cassette interface, the plate defining a vacuum aperture through which the vacuum is pulled around the piston head to the flexible sheet of the disposable cassette.

A peritoneal dialysis system comprising:

• a disposable cassette including a flexible sheet defining a pumping portion of a pump chamber;
• a pump actuator;
• a piston head moved by the pump actuator;
• a disposable cassette interface for interfacing with the disposable cassette, the disposable cassette interface including a pump opening, the piston head moveable out of and retractable into the pump opening to move the pumping portion of the flexible sheet of the disposable cassette, the piston head moving within a vacuum chamber, the vacuum chamber enabling a vacuum to be pulled around the piston head to the flexible sheet of the disposable cassette;
• and
• a plate to which the pump actuator is mounted, the plate defining a vacuum aperture through which the vacuum is pulled around the piston head to the flexible sheet of the disposable cassette.