Method for discriminating between operating conditions in medical pump

• US 20040120825A1
• Filed: 07/22/2003
• Published: 06/24/2004
• Est. Priority Date: 10/16/2002
• Status: Active Grant

• Current Assignee: Abbott Laboratories Incorporated
• Original Assignee: Abbott Laboratories Incorporated
• Inventors: Bouton, Chad E., Radcliff, Dale M., Fortney, Clark E., Nelson, Steven R.
• Granted Patent: US 7,104,763 B2
• Time in Patent Office: Days
• US Class Current: 417/44.2
• CPC Class Codes: A61M 2205/12 with interchangeable cassettes forming partially or totally the fluid circuit
• CPC Class Codes: A61M 2205/15 Detection of leaks
• CPC Class Codes: A61M 2205/332 Force measuring means
• CPC Class Codes: A61M 2205/3331 Pressure; Flow
• CPC Class Codes: A61M 5/14224 Diaphragm type
• CPC Class Codes: A61M 5/365 Air detectors A61M5/1684 takes precedence; in extracorporeal blood circuits A61M1/3626

Abstract

A method is disclosed for determining the operating condition of a medical pump based on data derived from a pressure sensor and a position sensor. The pressure sensor generates pressure data by sensing the force on the pumping element. The position sensor generates position data by tracking the pumping cycle and determining the position of the pumping element. The pump pressure data and pump position data are processed and the calculated results compared with a pre-determined threshold value to determine the operating condition of the pump. The three main types of operating conditions of concern are the following: normal condition, where liquid is present and no leaks exist in pumping chamber; leak condition, where liquid is present but a leak exists in the pumping chamber; and air stroke condition, where the chamber contains some air.

Claims

1. A method for determining operating conditions in a medical pump having a cassette with a pumping chamber, comprising:

monitoring the pump cycle with a position sensor;

closing the pumping chamber to flow during at least a portion of the pump cycle;

pressurizing the pumping chamber and acquiring a plurality of pressure data values from a single pressure sensor while the chamber is closed; and

processing the pressure data values to determine the operating condition of the pump.

2. The method of claim 1, wherein the operating condition determined is normal type, leak type, or air stroke.

3. A method for determining operating conditions in a medical pump having a cassette with a pumping chamber, comprising:

monitoring the pump cycle with a position sensor;

starting a testing timer for a pre-determined test time at a specified portion of the pump cycle;

closing the pumping chamber to flow during at least a portion of the specified portion of the pump cycle;

acquiring a plurality of pressure reference values during a first portion of test time from a single pressure sensor;

calculating and storing a pressure anchor value by averaging the reference values;

acquiring a pressure data value from the pressure sensor;

calculating and storing a resultant value by subtracting the anchor value from the data value;

repeating the steps of acquiring the pressure data value and calculating and storing the resultant value until the pre-determined test time has expired;

calculating a test value by averaging the resultant values; and

comparing the test value with pre-determined threshold value to determine the operating condition of the pump.

4. The method of claim 3, wherein the operating condition determined is normal type, leak type, or air stroke.

5. The method of claim 3, further comprising the step of smoothing the pressure reference values and pressure data values prior to performance of the calculation steps.

6. The method of claim 3, wherein the specified portion of the pump cycle is adjusted to reduce system variation sensitivity.

7. The method of claim 3, wherein the first portion of test time is adjusted to shorten the delay between the steps of starting the testing timer at the specified portion of the pump cycle and acquiring the pressure data value.

8. The method of claim 3, wherein the specified portion of the pump cycle and the first portion of test time are adjusted to vary the pressure anchor value.

9. The method of claim 3, wherein portions of the pressure reference values and pressure data values are weighted to adjust the emphasis of these portions.

10. A method for determining operating conditions in a medical pump having a cassette with a pumping chamber, comprising:

monitoring the pump cycle with a position sensor;

starting a testing timer for a pre-determined test time at a specified portion of the pump cycle;

closing the pumping chamber to flow during at least a portion of the specified portion of the pump cycle;

acquiring a plurality of pressure reference values during a first portion of test time from a single pressure sensor;

calculating and storing a pressure anchor value by averaging the reference values;

setting a first prior integration term of zero;

acquiring a pressure data value from the pressure sensor;

calculating and storing a new integration term by subtracting the anchor value from the data value to obtain a resultant, multiplying the resultant by a weighting value to obtain a product, and adding the product to the prior integration term;

repeating the steps of acquiring the pressure data value and calculating and storing the new integration term until the pre-determined test time has expired; and

comparing the new integration term with a pre-determined threshold value to determine the operating condition of the pump.

11. The method of claim 10, wherein the operating condition determined is normal type, leak type, or air stroke.

12. The method of claim 10, further comprising the step of smoothing the pressure reference values and pressure data values prior to performance of the calculation steps.

13. The method of claim 10, wherein the specified portion of the pump cycle is adjusted to reduce system variation sensitivity.

14. The method of claim 10, wherein the first portion of test time is adjusted to shorten the delay between the steps of starting the testing timer at the specified portion of the pump cycle and acquiring the pressure data value.

15. The method of claim 10, wherein the specified portion of the pump cycle and the first portion of test time are adjusted to vary the pressure anchor value.

16. The method of claim 10, wherein portions of the pressure reference values and pressure data values are weighted to adjust the emphasis of these portions.

17. A method for determining operating conditions in a medical pump having a cassette with a pumping chamber, comprising:

monitoring the pump cycle with a position sensor;

starting a testing timer for a pre-determined test time at a specified portion of the pump cycle;

closing the pumping chamber to flow during at least a portion of the specified portion of the pump cycle;

setting a first prior figure of merit value of zero;

acquiring a prior pressure data value from a single pressure sensor;

acquiring a new pressure data value from the pressure sensor, where the prior pressure data value is any data value other than the new pressure data value;

calculating and storing a new figure of merit value by subtracting the prior pressure data value from the new pressure data value to obtain a resultant, multiplying the resultant by a weighting value to obtain a product, and adding the product to the prior figure of merit;

repeating the steps of acquiring the new pressure data value and calculating and storing the new figure of merit value until the pre-determined test time has expired; and

comparing the figure of merit value with a pre-determined threshold value to determine the operating condition of the pump.

18. The method of claim 17, wherein the operating condition determined is normal type, leak type, or air stroke.

19. The method of claim 17, further comprising the step of smoothing the pressure reference values and pressure data values prior to performance of the calculation steps.

20. The method of claim 17, wherein the specified portion of the pump cycle is adjusted to reduce system variation sensitivity.

21. The method of claim 17, wherein the first portion of test time is adjusted to shorten the delay between the steps of starting the testing timer at the specified portion of the pump cycle and acquiring the pressure data value.

22. The method of claim 17, wherein the specified portion of the pump cycle and the first portion of test time are adjusted to vary the pressure anchor value.

23. The method of claim 17, wherein portions of the pressure reference values and pressure data values are weighted to adjust the emphasis of these portions.