Peritoneal dialysis methods that emulate gravity flow

A method for performing peritoneal dialysis comprising the steps of

• establishing flow communication among the patient's peritoneal cavity, a source of dialysis solution, and a drain through a pumping mechanism that comprises a pump chamber, at least one valve communicating with the pump chamber, and a diaphragm, and
• emulating a selected gravity flow condition by applying fluid pressure to the diaphragm to operate the pump chamber and valve to:
• (i) direct spent dialysis solution from the patient's peritoneal cavity into the pump chamber,
• (ii) direct the spent dialysis solution from the pump chamber to the drain,
• (iii) direct fresh dialysis solution from the source into the pump chamber, and
• (iv) direct the fresh dialysis solution from the pump chamber to the patient's peritoneal cavity.

A method for performing peritoneal dialysis comprising the steps of

• establishing flow communication among the patient's peritoneal cavity, a source of fresh dialysis solution, a reservoir for heating the fresh dialysis solution, and a drain through a pumping mechanism that comprises a pump chamber, at least one valve communicating with the pump chamber, and a diaphragm, and
• emulating a selected gravity flow condition by applying fluid pressure to the diaphragm to operate the pump chamber and valve to
• (i) direct spent dialysis solution from the patient's peritoneal cavity into the pump chamber,
• (ii) direct the spent dialysis solution from the pump chamber to the drain,
• (iii) direct fresh dialysis solution from the source into the pump chamber,
• (iv) direct the fresh dialysis solution from the pump chamber to the reservoir for heating,
• (v) direct the heated fresh dialysis solution from the reservoir into the pump chamber, and
• (vi) direct the heated fresh dialysis solution from the pump chamber to the patient's catheter.

A method for performing peritoneal dialysis comprising the steps of

• establishing flow communication with the patient's peritoneal cavity through a pumping mechanism that comprises a pump chamber and a diaphragm, and
• emulating a selected gravity flow condition by applying pneumatic pressure to the diaphragm through an actuator to operate the pump chamber to draw dialysis solution into the pump chamber and to expel dialysis solution from the pump chamber to either move dialysis solution from the peritoneal cavity or move dialysis solution into the peritoneal cavity, and
• deriving a measurement of liquid volume pumped through the pump chamber by deriving an initial air volume measurement V.sub.i after operating the actuator to draw fluid into the pumping chamber;
• deriving a final air volume measurement V.sub.f after operating the actuator to expel fluid from the pumping chamber;
• and deriving the liquid volume delivered (V.sub.d) by the pumping chamber as follows:
• V.sub.d =V.sub.f -V.sub.i, and
• wherein V.sub.i and V.sub.f are derived by controlling communication between a reference chamber having a known air volume V.sub.s and the actuator by:
• (i) when liquid is either drawn into or expelled from the pump chamber, closing communication between reference chamber and the actuator to initialize the reference chamber to a measured initial air pressure (IP.sub.s1) while applying a measured pressure to the actuator (IP.sub.d1);
• (ii) then opening communication between the reference chamber and the actuator to allow pressure equilibration at a measured new air pressure in the actuator (IP.sub.d2) and a measured new air pressure in the reference chamber (IP.sub.s2), and (iii) then deriving the air volume measurement V.sub.i or V.sub.f as follows:
• ##EQU4##