Medical Treatment System and Methods Using a Plurality of Fluid Lines

• US 20160101278A1
• Filed: 06/05/2015
• Published: 04/14/2016
• Est. Priority Date: 06/05/2014
• Status: Active Grant

• Current Assignee: Deka Products Limited Partnership
• Original Assignee: Deka Products Limited Partnership
• Inventors: Norris, Michael G., Scarpaci, Jacob W., Bryant, Robert J. Jr., Spencer, Geoffrey P., Hibbard, David J., Dale, James D., Kerwin, John M., Coll, Andrew S., Beavers, David A., McGill, David W., Helmore, Simon C., Doherty, David B., Bolton, Edgar J., Yoo, Jinsun, Girouard, Paul G., Karol, Daniel S., Singer, Daniel B., Rushlow, Joseph P.
• Granted Patent: US 10,058,694 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: A61M 1/1522 the interface being evacuated interfaces to enhance contact
• CPC Class Codes: A61M 1/1524 the interface providing means for actuating on functional elements of the cassette, e.g. plungers
• CPC Class Codes: A61M 1/154 with sensing means or components thereof
• CPC Class Codes: A61M 1/155 with treatment-fluid pumping means or components thereof
• CPC Class Codes: A61M 1/1561 at least one cassette surface or portion thereof being flexible, e.g. the cassette having a rigid base portion with preformed channels and being covered with a foil
• CPC Class Codes: A61M 1/1565 Details of valves
• CPC Class Codes: A61M 1/159 specially adapted for peritoneal dialysis
• CPC Class Codes: A61M 1/166 Heating for sterilisation A61M1/1686
• CPC Class Codes: A61M 1/28 Peritoneal dialysis ; Other peritoneal treatment, e.g. oxygenation
• CPC Class Codes: A61M 1/282 Operational modes
• CPC Class Codes: A61M 1/288 Priming priming in extracorporeal blood circuits A61M1/3643
• CPC Class Codes: A61M 2205/12 with interchangeable cassettes forming partially or totally the fluid circuit
• CPC Class Codes: A61M 2205/3331 Pressure; Flow
• CPC Class Codes: A61M 2205/3334 Measuring or controlling the flow rate
• CPC Class Codes: A61M 2205/3379 Masses, volumes, levels of fluids in reservoirs, flow rates
• CPC Class Codes: A61M 2205/3396 Reservoirs being alternately filled and emptied for measuring flow rate or delivered volume
• CPC Class Codes: A61M 2205/6063 Optical identification systems
• CPC Class Codes: A61M 39/22 Valves or arrangement of valves A61M39/02, A61M39/0247, A61M39/16 take precedence; regulating valves in infusion systems A61M5/16881; in devices worn by the patient for the reception of urine, faeces, catamenial or other discharge, or in colostomy devices A61F5/4405
• CPC Class Codes: A61M 5/14224 Diaphragm type
• CPC Class Codes: A61M 5/14244 adapted to be carried by the patient, e.g. portable on the body
• CPC Class Codes: A61M 5/14586 : pressurised by means of a flexible diaphragm
• CPC Class Codes: A61M 5/155 : pressurised by gas introduced into the reservoir
• CPC Class Codes: A61M 60/113 : in other functional devices, e.g. dialysers or heart-lung machines
• CPC Class Codes: A61M 60/205 : Non-positive displacement blood pumps
• CPC Class Codes: A61M 60/268 : the displacement member being flexible, e.g. membranes, diaphragms or bladders
• CPC Class Codes: A61M 60/37 : Haemodialysis, haemofiltration or diafiltration
• CPC Class Codes: A61M 60/38 : Blood oxygenation
• CPC Class Codes: A61M 60/40 : Details relating to driving
• CPC Class Codes: A61M 60/43 : using vacuum at the blood pump, e.g. to accelerate filling
• CPC Class Codes: A61M 60/50 : Details relating to control
• CPC Class Codes: A61M 60/538 : Regulation using real-time blood pump operational parameter data, e.g. motor current
• CPC Class Codes: A61M 60/837 : Aspects of flexible displacement members, e.g. shapes or materials
• CPC Class Codes: A61M 60/892 : Active valves, i.e. actuated by an external force
• CPC Class Codes: A61M 60/894 : Passive valves, i.e. valves actuated by the blood

Abstract

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. 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. Improvements are also disclosed in the application of negative pressure during a drain phase in peritoneal dialysis therapy, and to control the amount of intraperitoneal fluid accumulation during a therapy. Improvements in efficiency are also disclosed in the movement of fluid into and out of a two-pump cassette and heater bag of a peritoneal dialysis cycler, and in the synchronization of the operation of two or more pumps in a peritoneal dialysis cycler or other fluid handling devices using a multi-pump arrangement.

Claims

1. A system for measuring an amount of liquid in a pumping chamber of a pneumatically actuated diaphragm pump comprising:

a fluid inlet and fluid outlet valve connected to the pumping chamber;

a diaphragm separating a pneumatically actuated control chamber from the pumping chamber, the control chamber fluidly connected to a reference chamber of known volume via a conduit that includes a reference chamber valve;

the control chamber fluidly connected via one or more actuation valves to a source of positive or negative pneumatic pressure;

a controller configured to control the fluid inlet and outlet valves, the reference chamber valve, and the one or more actuation valves, and to receive pressure data from a first pressure sensor connected to the actuation chamber and a second pressure sensor connected to the reference chamber,

wherein the controller is configured to isolate the pumping chamber by closing the fluid inlet and outlet valves, charge the control chamber with a first pneumatic pressure;

vent the reference chamber or fix a pneumatic pressure in the reference chamber that is different from the control chamber pneumatic pressure;

measure a first control chamber pressure and a first reference chamber pressure, connect the control chamber to the reference chamber by opening the reference chamber valve, measure a third equalized pneumatic pressure in the control and reference chambers, and

compute a control chamber volume based on an ideal gas model that assumes an adiabatic pressure equalization process in the reference chamber and a polytropic pressure equalization process in the control chamber.

2. The system of claim 1, wherein the model further assumes an isothermal process in the conduit as a gas moves from the control chamber to the reference chamber during the equalization process.

3. The system of claim 1, wherein the model applied to the control chamber uses a polytropic coefficient in the ideal gas model, wherein the controller is programmed to vary the polytropic coefficient as a pre-defined function of the control chamber volume.

4. The system of claim 3, wherein the controller is programmed to compute a polytropic coefficient based on an estimated volume of the control chamber using a model that assumes an adiabatic pressure equalization process in the control chamber.

5. A system for measuring an amount of liquid in a pumping chamber of a pneumatically actuated diaphragm pump comprising:

a fluid inlet and fluid outlet valve connected to the pumping chamber;

a diaphragm separating a pneumatically actuated control chamber from the pumping chamber, the control chamber fluidly connected to a reference chamber of known volume via a conduit that includes a reference chamber valve;

the control chamber fluidly connected via one or more actuation valves to a source of positive or negative pneumatic pressure;

a controller configured to control the fluid inlet and outlet valves, the reference chamber valve, and the one or more actuation valves, and to receive pressure data from a first pressure sensor connected to the actuation chamber and a second pressure sensor connected to the reference chamber,

wherein the controller is configured to isolate the pumping chamber by closing the fluid inlet and outlet valves, charge the control chamber with a first pneumatic pressure;

vent the reference chamber or fix a pneumatic pressure in the reference chamber that is different from the control chamber pneumatic pressure;

measure a first control chamber pressure and a first reference chamber pressure, connect the control chamber to the reference chamber by opening the reference chamber valve and equalizing pressures between the control chamber and the reference chamber, measure a third equalized pneumatic pressure in the control and reference chambers, and

compute a control chamber volume based on an ideal gas model that assumes the presence of three closed mass systems of a gas comprising;

a first mass system that occupies the control chamber at the end of pressure equalization;

a second mass system that occupies the reference chamber before pressure equalization; and

a third mass system that occupies the conduit, a part of the control chamber and a part of the reference chamber after equalization of pressure begins between the control and reference chambers.

6. The system of claim 5, wherein the model assumes an expansion of the first mass system after pressure equalization begins, the expansion being modeled as a polytropic process.

7. The system of claim 5, wherein the model assumes a compression of the second mass system after pressure equalization begins, the compression being modeled as an adiabatic process.

8. The system of claim 5, wherein the third mass system is modeled to be subdivided into component volumes, a first component volume occupying part of the control chamber and being modeled polytropically, a second component volume occupying part of the reference chamber and being modeled adiabatically, and a third component volume occupying the conduit and being modeled isothermally.

9. A system for measuring an amount of liquid in a pumping chamber of a pneumatically actuated diaphragm pump comprising:

a fluid inlet and fluid outlet valve connected to the pumping chamber;

a diaphragm separating a pneumatically actuated control chamber from the pumping chamber, the control chamber fluidly connected to a reference chamber of known volume via a conduit that includes a reference chamber valve;

the control chamber fluidly connected via one or more actuation valves to a source of positive or negative pneumatic pressure;

a controller configured to control the fluid inlet and outlet valves, the reference chamber valve, and the one or more actuation valves, and to receive pressure data from a first pressure sensor connected to the actuation chamber and a second pressure sensor connected to the reference chamber;

wherein the controller is configured to isolate the pumping chamber by closing the fluid inlet and outlet valves, charge the control chamber with a first pneumatic pressure;

vent the reference chamber or fix a pneumatic pressure in the reference chamber that is different from the control chamber pneumatic pressure;

measure a first control chamber pressure and a first reference chamber pressure, connect the control chamber to the reference chamber by opening the reference chamber valve and equalizing pressures between the control chamber and the reference chamber, measure a third equalized pneumatic pressure in the control and reference chambers, and

compute the control chamber volume based on an ideal gas model that assumes the presence of three closed mass systems of a gas comprising;

a first mass system that occupies the control chamber before pressure equalization;

a second mass system that occupies the reference chamber at the end of pressure equalization; and

a third mass system that occupies the conduit, a part of the control chamber and a part of the reference chamber after equalization of pressure begins between the control and reference chambers.

10. The system of claim 9, wherein the model assumes a compression of the first mass system after pressure equalization begins, the compression being modeled as a polytropic process.

11. The system of claim 9, wherein the model assumes an expansion of the second mass system after pressure equalization begins, the expansion being modeled as an adiabatic process.

12. The system of claim 9, wherein the third mass system is modeled to be subdivided into component volumes, a first component volume occupying part of the control chamber being modeled polytropically, a second component volume occupying part of the reference chamber being modeled adiabatically, and a third component volume occupying the conduit being modeled isothermally.

13. A system for measuring an amount of liquid in a pumping chamber of a pneumatically actuated diaphragm pump comprising:

a fluid inlet and fluid outlet valve connected to the pumping chamber;

a diaphragm separating a pneumatically actuated control chamber from the pumping chamber, the control chamber fluidly connected to a reference chamber of known volume via a conduit that includes a reference chamber valve;

the control chamber fluidly connected via one or more actuation valves to a source of positive or negative pneumatic pressure;

a controller configured to control the fluid inlet and outlet valves, the reference chamber valve, and the one or more actuation valves, and to receive pressure data from a first pressure sensor connected to the actuation chamber and a second pressure sensor connected to the reference chamber;

wherein the controller is configured to isolate the pumping chamber by closing the fluid inlet and outlet valves, charge the control chamber with a first pneumatic pressure;

vent the reference chamber or fix a pneumatic pressure in the reference chamber that is different from the control chamber pneumatic pressure;

measure a first control chamber pressure and a first reference chamber pressure, connect the control chamber to the reference chamber by opening the reference chamber valve and equalizing pressures between the control chamber and the reference chamber, measure a third equalized pneumatic pressure in the control and reference chambers, and

compute a control chamber volume based on an ideal gas model under a polytropic process, wherein the controller is configured to select a polytropic coefficient for the model using a pre-determined function in which the value of the polytropic coefficient depends on and varies with the control chamber volume.

14. The system of claim 13, wherein the pre-determined function is determined by fixing the control chamber volume at a known volume, and calculating a polytropic coefficient corresponding to the known volumes of the control and reference chambers, and the measured first, second and third pressures before and after equalization of pressures;

wherein said calculation is repeated a plurality of times, each said time corresponding to fixing the control chamber volume at a different known volume.

15. The system of claim 14, wherein the function corresponds to a stored look-up table from which the controller selects a polytropic coefficient corresponding to the volume of the control chamber being computed.

16. The system of claim 14, wherein the function corresponds to an equation that has been fitted to a plurality of calculated polytropic coefficients corresponding to a series of known control chamber volumes.

17. A system for calculating a change in fluid volume in a pumping chamber of a pneumatically actuated diaphragm pump using a gas having a heat capacity ratio of n, the system comprising:

a control chamber separated from the pumping chamber by a flexible diaphragm;

a fluid inlet or outlet of the pumping chamber;

a valve connecting the control chamber to a pressurized source of the gas;

a pressure sensor fluidly connected to the control chamber,

a controller that receives pressure data from the pressure sensor, that controls the valve, and that is configured to regulate pressure in the control chamber by opening or closing the valve;

wherein the controller is configured to compute a change in volume of the control chamber as fluid enters or leaves the pumping chamber by monitoring a pressure change in the control chamber when the valve is closed;

said computation assigning a first chamber volume to a first measured pressure, and calculating a second chamber volume based on a second later measured pressure using an equation in which a ratio of the second measured pressure to the first measured pressure is assumed to be equal to a ratio of the first chamber volume to the second chamber volume, raised to a power between 1 and n.

18. The system of claim 17, wherein the assigned first chamber volume is derived from an initial condition in which the control chamber is pressurized with air, the pumping chamber and control chamber are isolated, a measurement of control chamber pressure is taken, the control chamber is connected to a reference chamber having a known volume and measured pressure, and the controller derives an initial volume of the control chamber using a model based on an ideal gas equation.

19. The system of claim 17, wherein the controller calculates a third chamber volume as fluid continues to enter or leave the pumping chamber by assigning the second chamber volume to the second measured pressure and calculating a third chamber volume based on a third measured pressure using an equation in which a ratio of the third measured pressure to the second measured pressure is assumed to be equal to a ratio of the second chamber volume to the third chamber volume, raised to a power between 1 and n.

20. The system of claim 19, wherein the controller calculates a fluid flow into or out of the pumping chamber based on a difference between the first, second and third chamber volumes.

21. The system of claim 20, wherein the controller repeats said calculations periodically during a time period in which fluid continues to enter or leave the pumping chamber, and suspends said calculations during a time period in which the valve is opened to connect the control chamber with the pressurized source of the gas.

22. The system of claim 21, wherein the pressurized source of the gas is a positively pressurized source or a negatively pressurized source.

23. The system of claim 22, wherein the gas is air.

24. The system of claim 22, wherein the value of n is approximately 1.4.

25. The system of claim 24, wherein the value of n is adjusted by the controller by comparing a cumulative calculated volume of fluid moved into or out of the pumping chamber during a pump stroke to a volume change in the pumping chamber calculated from an initial volume determination at a beginning of the pump stroke and a final volume determination at an end of the pump stroke.

26-54. -54. (canceled)