Pumping systems for cassette-based dialysis

A peritoneal dialysis method comprising:

• enabling the mating of a disposable pumping cassette with a peritoneal dialysis machine;
• moving first and second pistons heads towards the disposable pumping cassette to contact and move first and second respective portions of a flexible membrane of the pumping cassette into a rigid portion of the pumping cassette to push (i) fresh dialysate out of the pumping cassette through a patient line towards a patient or (ii) spent dialysate to a drain line towards a drain;
• and
• applying a first vacuum to mate the first portion of the flexible membrane to the first piston head and a second vacuum to mate the second portion of the flexible membrane to the second piston head to cause the first and second portions of the flexible membrane to respectively follow the first and second piston heads as either piston head is moved away from the pumping cassette to pull (i) fresh dialysate from a fresh dialysate supply line or (ii) spent dialysate from the patient line to fill a respective first or second pump chamber of the pumping cassette.

A peritoneal dialysis method comprising:

• enabling a disposable cassette to be aligned so that (i) a soft side of the disposable cassette faces towards a vacuum chamber and a piston head of a peritoneal dialysis machine and (ii) a dialysis fluid supply line, a patient line and a drain line extend from a hard part of the disposable cassette outside of the peritoneal dialysis machine to a respective dialysis fluid supply container, a patient and a drain;
• positioning the piston head relative to the vacuum chamber;
• applying a vacuum through the vacuum chamber to pull the soft side of the disposable cassette to the piston head to at least partially mate the soft side of the disposable cassette with the piston head;
• pushing fresh dialysis fluid from the disposable cassette through the patient line or spent dialysis fluid from the disposable cassette through the drain line as the piston head and the soft side of the disposable cassette are extended at least partially into the hard part of the disposable cassette;
• and
• drawing fresh dialysis fluid through the supply line or spent dialysis fluid through the patient line into the disposable cassette as the piston head retracts from the hard part of the disposable cassette while using the vacuum to hold the soft side of the disposable cassette in at least partial contact with the piston head.