System for regulating fluid pump pressures

• US 20030086794A1
• Filed: 12/16/2002
• Published: 05/08/2003
• Est. Priority Date: 07/10/2000
• Status: Active Grant

• Current Assignee: Larry Gray, Robert Bryant
• Original Assignee: Larry Gray, Robert Bryant
• Inventors: Gray, Larry, Bryant, Robert
• Granted Patent: US 6,808,369 B2
• Time in Patent Office: Days
• US Class Current: 417/279
• CPC Class Codes: A61M 1/152 Details related to the interface between cassette and machine
• CPC Class Codes: A61M 1/155 with treatment-fluid pumping means or components thereof
• CPC Class Codes: A61M 1/1565 Details of valves
• CPC Class Codes: A61M 1/159 specially adapted for peritoneal dialysis
• CPC Class Codes: A61M 1/282 Operational modes
• CPC Class Codes: A61M 2205/3331 Pressure; Flow
• CPC Class Codes: A61M 5/16809 by repeated filling and emptying of an intermediate volume pressure infusion using positive displacement pumps A61M5/142
• CPC Class Codes: F04B 43/06 Pumps having fluid drive
• CPC Class Codes: G05D 16/2073 with a plurality of pressure sources
• CPC Class Codes: G05D 7/0635 by action on throttling means G05D7/0688, G05D7/0694 take precedence
• CPC Class Codes: Y10T 137/0318 Processes

Abstract

A method is provided for regulating fluid pump pressures by detecting an elevation differential between a fluid flow control device and the distal end of a fluid line in communication with the fluid flow control device. A fluid flow control device, for instance a peritoneal dialysis device, is at a first height, a distal end of a fluid line is at a second height, and a valved outlet, when open, affords communication between the fluid flow control device and the distal end of the fluid line. The elevation differential is correlatable with a pressure measurable during a calibration procedure provided as a part of the methodology.

Claims

1. A method for regulating fluid pump pressures, the method comprising:

providing a fluid flow control device, the fluid flow control device having at least one liquid volume in valved communication with a distal end of a fluid line;

calibrating the pressure in the liquid volume;

establishing communication between the liquid volume and the distal end;

measuring a pressure associated with the liquid volume; and

adjusting the fluid pump pressure in accordance with the measured pressure.

2. A method according to claim 1, wherein calibrating the liquid volume comprises:

isolating the liquid volume from the distal end;

measuring a first calibration pressure of a control volume in pressure communication with the liquid volume;

pressurizing the liquid volume; and

measuring a second calibration pressure of the control volume.

3. A method according to claim 1, wherein calibrating the liquid volume comprises:

isolating the liquid volume from the distal end;

measuring the pressure of a control volume in pressure communication with the liquid volume;

positively pressurizing the liquid volume;

measuring the pressure of the control volume while the liquid volume is positively pressurized;

negatively pressurizing the liquid volume; and

measuring the pressure of the control volume while the liquid volume is negatively pressurized.

4. A method according to claim 1, wherein the liquid volume includes a flexible membrane, which separates the liquid volume from a control volume where pressure measurements are made.

5. A method according to claim 1, wherein the fluid flow control device includes a pump.

6. A method for regulating fluid pump pressures, the method comprising:

providing a fluid flow control device, the fluid flow control device having a first liquid volume and a second liquid volume, the first liquid volume in valved communication with the second liquid volume;

providing a fluid line, the fluid line having a distal end in valved communication with the first liquid volume and the second liquid volume;

calibrating the pressures in the liquid volumes;

establishing communication between the first liquid volume and the distal end;

measuring a pressure associated with the first liquid volume;

adjusting the fluid pump pressure in accordance with the measured pressure.

7. A method according to claim 6, wherein calibrating the liquid volumes comprises:

isolating the liquid volumes from the distal end;

measuring first calibration pressures associated with the first liquid volume and the second liquid volume;

pressurizing the first liquid volume;

measuring a second calibration pressure associated with the second liquid volume; and

adjusting the fluid pump pressure in accordance with the measured pressures.

8. A method according to claim 6, wherein calibrating the liquid volumes comprises:

isolating the liquid volumes from the distal end;

measuring first calibration pressures associated with the first liquid volume and the second liquid volume;

positively pressurizing the first liquid volume;

measuring a second calibration pressure associated with the second liquid volume while the first liquid volume is positively pressurized;

negatively pressurizing the first liquid volume;

measuring a third calibration pressure associated with the second liquid volume while the first liquid volume is negatively pressurized; and

adjusting the fluid pump pressure in accordance with the measured pressures.

9. A method according to claim 6, wherein each of the first and second liquid volumes includes a flexible membrane that separates the liquid volume from a control volume, and wherein the pressure measurements are taken from the control volume.

10. A method according to claim 6, wherein the first and second liquid volumes are disposed within a cassette.

11. A method according to claim 10, wherein the fluid flow control device includes a pump.

12. A method for estimating the relative elevation between a first location and a second location, the method comprising:

placing a fluid flow control device at the first location, the fluid flow control device having a membrane pump in valved communication with the second location, the membrane pump having a pressure transducer;

isolating the membrane pump from the second location;

calibrating the pressure transducer;

establishing communication between the membrane pump and the second location;

measuring the pressure in the membrane pump with the pressure transducer; and

estimating the relative elevation based on the pressure.

13. A method according to claim 12, wherein calibrating the pressure transducer comprises:

filling the membrane pump with fluid in pressure equilibrium with the pressure at the first location;

measuring a first calibration pressure in the membrane pump;

filling the membrane pump with fluid in pressure equilibrium with a known calibration pressure;

measuring a second calibration pressure in the membrane pump; and

estimating the relative elevation by constructing a linear fit between pressure and relative elevation based on the known calibration pressure, the first calibration pressure, and the second calibration pressure.

14. A method according to claim 13, wherein the relative elevation is determined by a processor.

15. A computer program product for use on a processor for determining an elevation differential between a first location and a second location, wherein a fluid flow control device is located at the first location, the fluid flow control device including at least one liquid volume in valved communication with a second location via a distal end of a fluid line, the computer program product comprising a computer usable medium having computer readable program code thereon, the computer readable program code including:

program code for reading and storing pressure values within the pumps;

program code for computing and identifying correlations between stored pressure values;

program code for calculating pressure values based on the identified correlations; and

program code for estimating the elevation differential based upon the calculated pressures.

16. The computer program product according to claim 15, further comprising:

program code for calculating a desired pumping pressure based upon the elevation differential; and

program code for adjusting the pumping pressured withing the fluid flow control device in accordance with the desired pumping pressure.

17. A computer program product for use on a processor for regulating fluid pump pressures, wherein a fluid flow control device is located at the first location, the fluid flow control device including at least one liquid volume in valved communication with a second location via a distal end of a fluid line, the computer program product comprising a computer usable medium having computer readable program code thereon, the computer readable program code including:

program code for reading and storing pressure values within the pumps;

program code for computing and identifying correlations between stored pressure values;

program code for calculating pressure values based on the identified correlations; and

program code for calculating a desired pumping pressure based on the identified correlations.

18. A fluid flow control device for detecting an elevation differential between a first location and a second location, wherein the device is located at the first location, the fluid flow control device comprising:

at least one liquid volume;

a fluid line in valved pressure communication with the liquid volume, the fluid line having a distal end located at the second location;

at least one transducer for measuring pressure associated with the liquid volume; and

a processor for;

reading and storing pressure values;

computing and identifying a correlation between the pressure values;

calculating pressure values based on the identified correlations; and

estimating the elevation differential based upon the calculated pressures.

19. A device according to claim 18, wherein the correlation computed and identified is a linear fit.

20. A device according to claim 18, wherein the liquid volume includes a flexible membrane that separates the liquid volume from a control volume, and wherein the pressure measurements are taken from the control volume.

21. A device according to claim 18, wherein the liquid volume is disposed within a cassette.

22. A device according to claim 18, further comprising at least one pump.

23. A device according to claim 18, further comprising at least one piston.

24. A system for regulating fluid pump pressures, the system comprising:

a fluid flow control device having at least one liquid volume in valved communication with a distal end of a fluid line, the fluid flow control device including pressure means for pressurizing the liquid volume;

a valve arrangement for controlling fluid communication between the at least one liquid volume and the distal end;

a transducer for measuring a pressure associated with the at least one liquid volume; and

a controller for controlling the valve arrangement, the means for pressurizing the liquid volume, and the fluid pump pressure, and wherein the controller adjusts the fluid pump pressure in accordance with the pressure measured by the transducer.

25. A system for regulating fluid pump pressures, the system comprising:

a fluid flow control device having first and second liquid volumes in valved communication with each other and with a distal end of a fluid line, the fluid flow control device including means for pressurizing at least one liquid volume;

a valve arrangement for controlling fluid communication between the liquid volumes and between the liquid volumes and the distal end;

a transducer for measuring a pressure associated with at least one liquid volume; and

a controller for controlling the valve arrangement, the means for pressurizing the liquid volumes, and the fluid pump pressure, and wherein the controller adjusts the fluid pump pressure in accordance with the pressure measured by the transducer.

26. A system according to claim 25, wherein the controller causes:

the valve arrangement to isolate the liquid volumes from the distal end;

the transducer to measure the pressure associated with the first liquid volume, while it is isolated from the distal end;

the means for pressurizing the second liquid volume; and

measuring the pressure associated with the first liquid volume after the pressure in the second liquid volume has been pressurized.

27. A system according to claim 25, wherein the liquid volumes include a flexible membrane.

28. A system according to claim 27, wherein at least one liquid volume is disposed within a cassette.