Improvements in fluid volume measurement systems are disclosed for a pneumatically actuated diaphragm pump in general, and a peritoneal dialysis cycler using a pump cassette in particular. Pump fluid volume measurements are based on pressure measurements in a pump control chamber and a reference chamber in a two-chamber model, with different sections being modeled using a combination of adiabatic, isothermal and polytropic processes. Real time or instantaneous fluid flow measurements in a pump chamber of the diaphragm pump are also disclosed, in this case using a one-chamber ideal gas model and using a high speed processor to obtain and process pump control chamber pressures during fluid flow into or out of the pump chamber. Improved heater control circuitry is also disclosed, to provide added or redundant safety measures, or to reduce current leakage from a heater element during pulse width modulation control of the heater element. Improvements are also disclosed in an application of negative pressure during a drain phase in peritoneal dialysis therapy, and to control an amount of intraperitoneal fluid accumulation during the therapy. Improvements in efficiency are also disclosed in movement of fluid into and out of a two-pump cassette and a heater bag of the peritoneal dialysis cycler, and in synchronization of operation of two or more pumps in the peritoneal dialysis cycler or other fluid handling devices using a multi-pump arrangement.

Improvements in fluid volume measurement systems are disclosed for a pneumatically actuated diaphragm pump in general, and a peritoneal dialysis cycler using a pump cassette in particular. Pump fluid volume measurements are based on pressure measurements in a pump control chamber and a reference chamber in a two-chamber model, with different sections of the apparatus being modeled using a combination of adiabatic, isothermal and polytropic processes. Real time or instantaneous fluid flow measurements in a pump chamber of a diaphragm pump are also disclosed, in this case using a one-chamber ideal gas model and using a high speed processor to obtain and process pump control chamber pressures during fluid flow into or out of the pump chamber.

A dialysis machine (e.g., a peritoneal dialysis (PD) machine) can include a safety feature that is used to isolate individual fluid lines attached to a disposable cassette. The PD machine can include an interface for a disposable cassette, a plurality of safety mechanisms, and a processor. A plurality of fluid lines are connected to the disposable cassette, and each safety mechanism corresponds to a particular fluid line in the plurality of fluid lines. The processor is configured to detect a hazard condition, such as a loss of power to the PD machine or leak in the disposable cassette, and activate one or more safety mechanisms to isolate corresponding fluid lines connected to the disposable cassette. In one embodiment, the safety mechanisms are spring-loaded clamping mechanisms configured to compress a distensible tube connected to the fluid line. In another embodiment, the safety mechanisms include relay solenoids and/or check valves.

A fluid handling cassette, such as that useable with an automated peritoneal dialysis (APD) cycler device or other infusion apparatus, may include a generally planar body having at least one pump chamber formed as a depression in a first side of the body and a plurality of flowpaths for a fluid that includes a channel. A patient line port may be arranged for connection to a patient line and be in fluid communication with the at least one pump chamber via at least a first one of said flowpaths, and an optional membrane may be attached to the first side of the body over the at least one pump chamber. In one embodiment, the membrane may have a pump chamber portion with an unstressed shape that generally conforms to the depression of the at least one pump chamber in the body and is arranged to be movable for movement of the fluid in a useable space of the at least one pump chamber. One or more spacers may be provided in the at least one pump chamber to prevent the membrane from contacting an inner wall of the at least one pump chamber. The patient line, a drain line, and/or a heater bag line may be positioned to be separately occludable in relation to one or more solution lines that are connectable to the cassette.

A dialysis system is disclosed. The example dialysis system includes a housing, a pump actuator housed by the housing, a fluid pumping cassette coupled operably to the housing and including a flexible membrane covering a pump chamber, and a mechanically actuated piston head provided by the pump actuator and positioned to extend towards and away from the fluid pumping cassette. The fluid pumping cassette is positioned such that the flexible membrane of the fluid pumping cassette faces the piston head so that the piston head can push the flexible membrane into the pump chamber of the fluid pumping cassette to expel a fluid from the pump chamber. The example dialysis system also includes a controller programmed to perform a leak test by monitoring a sensed position of the mechanically actuated piston head while the mechanically actuated piston head applies a force to the flexible membrane of the fluid pumping cassette.

Components for a medical infusion fluid handling system, such as an APD system, in which one or more lines (such as solution lines), spikes or other connection ports may be automatically capped and/or de-capped. This feature may provide advantages, such as a reduced likelihood of contamination since no human interaction is required to de-cap and connect the lines, spikes or other connections. For example, a fluid handling cassette may include one or more caps that cover a corresponding spike and include a raised and/or recessed feature to assist in removal of the cap from the cassette. A solution line cap may include a hole and recess, groove or other feature to engage with a spike cap and enable removal of the cap.

A peritoneal dialysis system includes first and second concentrate sources in selective fluid communication with a medical fluid pumping cassette, the first and second concentrate sources holding first and second peritoneal dialysis concentrates, respectively; a pump actuator configured to cause the medical fluid pumping cassette to pump the first and second concentrates; and a processor and memory configured to (i) determine a cumulative volume of at least one of the first or second peritoneal dialysis concentrates pumped from the medical fluid pumping cassette by the pump actuator, (ii) compare the cumulative volume to a threshold, and (iii) if the cumulative volume is outside of the threshold, modify a subsequent stroke volume of at least one of the first or second pump chambers actuated by the pump actuator in an attempt to cause an updated cumulative volume for the at least one peritoneal dialysis concentrate to be within the threshold.

An example peritoneal dialysis system is disclosed. The example peritoneal dialysis system includes at least one pump and a memory device configured to store therapy prescriptions including a low ultrafiltration (“UF”) therapy prescription, a first standard UF therapy prescription with a longer duration and a lower dextrose concentration, and a second standard UF therapy prescription with a shorter duration and a higher dextrose concentration. The memory device also stores a schedule indicative as to which of the therapy prescriptions are to be performed on specified dates. The system further includes a logic implementer configured to determine or identify a current date, use the schedule stored in the memory device to select the therapy prescription based on the current date, and control the at least one pump based on the selected therapy prescription to perform a peritoneal dialysis therapy.

Improvements in fluid volume measurement systems are disclosed for a pneumatically actuated diaphragm pump in general, and a peritoneal dialysis cycler using a pump cassette in particular. Pump fluid volume measurements are based on pressure measurements in a pump control chamber and a reference chamber in a two-chamber model, with different sections of an apparatus being modeled using a combination of adiabatic, isothermal and polytropic processes. Real time or instantaneous fluid flow measurements in a pump chamber of the diaphragm pump are also disclosed, in this case using a one-chamber ideal gas model and using a high speed processor to obtain and process pump control chamber pressures during fluid flow into or out of the pump chamber.

A method for performing a peritoneal dialysis therapy includes performing a plurality of peritoneal dialysis cycles for a patient and tracking an amount of dialysis fluid provided by at least one dialysis fluid pump during the plurality of peritoneal dialysis cycles. The method also includes determining an amount of ultrafiltrate (“UF”) removed from the patient based on the amount of dialysis fluid provided by the at least one dialysis fluid pump. The method further includes updating a UF trend using previous amounts of UF removed from the patient and the amount of UF removed from the patient during the most recent dialysis treatment and generating an alert if the UF trend changes by more than a preset percentage.