Optical pressure monitoring system

• US 6,907,788 B2
• Filed: 11/08/2002
• Issued: 06/21/2005
• Est. Priority Date: 04/16/2001
• Status: Expired due to Term

• Current Assignee: Zevex (Moog Incorporated)
• Original Assignee: Zevex (Moog Incorporated)
• Inventors: Beck, Kent F., Miles, Scott D., Malmstrom, James A.
• Primary Examiner(s): OEN, WILLIAM L
• Application Number:
  US10/290,557
• Publication Number:
  US 20030070486A1
• Time in Patent Office: 956 Days
• Field of Search: 737/05, 737/14, 250/227.21, 250/227.23, 250/231.19
• US Class Current: 73/705
• CPC Class Codes: A61M 2202/0482 Enteral feeding product
• CPC Class Codes: A61M 2205/3306 Optical measuring means
• CPC Class Codes: A61M 2205/3351 Controlling upstream pump pressure
• CPC Class Codes: A61M 2205/3355 Controlling downstream pump pressure
• CPC Class Codes: A61M 5/14232 Roller pumps
• CPC Class Codes: A61M 5/16854 by monitoring line pressure
• CPC Class Codes: G01L 9/0007 using photoelectric means G01L9/0076 takes precedence

Abstract

An optical pressure monitoring system includes a tube from an infusion set and an optical signal sensor disposed to detect changes in the diameter of the tube and thereby determine pressure changes within the tube. By selecting the position of the tube relative to the optical signal emitter and optical signal receiver, the optical signal sensor can both detect pressure changes and provide an integrity check for both the functioning of the optical signal sensor and the placement of the tube. By modifying the tube to exaggerate changes in tube diameter responsive to pressure changes, the sensitivity of the optical signal sensor can be increased.

Claims

1. An optical pressure monitoring system comprising:

an optical signal sensor having an optical signal emitter and an optical signal receiver; and

a radially expandable tube disposed at least partially between the optical signal emitter and the optical signal sensor, the tube being configured to change diameter in response to pressure changes within the tube.

2. The optical pressure monitoring system according to claim 1, wherein the optical signal receiver receives an optical emission from the optical signal emitter and converts said emission into a voltage, the system further comprising voltage measuring means for determining change in the radially expandable tube'"'"'s diameter.

3. The optical pressure monitoring system according to claim 1, wherein the radially expandable tube is positioned between the optical signal sensor and the optical signal emitter so that the tube always at least partially obstructs the transmission of optical signals from the optical signal emitter to the optical signal receiver.

4. The optical pressure monitoring system according to claim 1, wherein the tube is positioned so that the tube does not obstruct all optical signals sent from the optical signal emitter to the optical signal receiver.

5. The optical pressure monitoring system according to claim 1, wherein the radially expandable tube comprises a thin-walled portion which expands more readily than other portions of the tube.

6. The optical pressure monitoring system according to claim 5, wherein the thin-walled portion of the radially expandable tube is positioned between the optical emitter and the optical receiver.

7. The optical pressure monitoring system according to claim 1, further comprising a jacket disposed about the radially expandable tube.

8. The optical pressure monitoring system according to claim 7, wherein the jacket has an opening therein.

9. The optical pressure monitoring system according to claim 8, wherein the opening is disposed between the optical signal emitter and the optical signal receiver.

10. The optical pressure monitoring system according to claim 1, wherein the radially expandable tube comprises a piece of generally rigid tubing having an opening along a wall thereof, and a piece of flexible tube, the flexible tube covering the opening in the rigid tube.

11. The optical pressure monitoring system according to claim 10, wherein the opening in the rigid tube is disposed between the optical signal emitter and the optical signal receiver.

12. The optical pressure monitoring system according to claim 1, further comprising an abutment member for limiting the expansion of the radially expandable tube in at least one direction.

13. The optical pressure monitoring system according to claim 12, wherein the abutment member is configured for pushing the tube between the optical signal emitter and the optical signal receiver.

14. The optical pressure monitoring system according to claim 13, wherein the abutment member has an end which engages the tube, and wherein the end has a radius which is smaller than the tube.

15. The optical pressure monitoring system according to claim 13, wherein the abutment member has a cross-section which is generally square.

16. The optical pressure monitoring system according to claim 13, wherein the abutment member has a semi-oval cross-section.

17. The optical pressure monitoring system according to claim 13, wherein the abutment member has a triangular cross-section.

18. An optical pressure monitoring system comprising:

a flexible tube for carrying a liquid;

an optical emitter disposed on one side of the tube;

an optical detector disposed on another side of the tube approximately opposite the optical emitter, such that the tube partially obstructs the optical signal path between the emitter and detector, and whereby pressure in the tube causes visually perceivable expansion of the diameter of the tube.

19. The system of claim 18, wherein the tube is constructed of an elasticly stretchable material.

20. The system of claim 18, wherein the tube selectively expands and contracts in diameter in response to increases and decreases in the pressure within the tubing and thereby selectively allows an increased or decreased amount of light to pass from the emitter to the detector.

21. The system of claim 18, further comprising a jacket disposed about the tube to selectively allow expansion of the tube in certain portions of the tube and prevent expansion of the tube in other portions of the tube.

22. The system of claim 18, wherein a potion of the tube has a wall which is thinner than the rest of the tube, thereby exaggerating expansion in the thin wall portion of the tube.

23. The system of claim 18, further comprising at least one wall disposed adjacent the tube to inhibit expansion of the tube.

24. The system of claim 18, further comprising a pair of walls disposed on generally opposite sides of the tube to thereby selectively inhibit expansion of the tube.

25. The system of claim 18, further comprising a channel disposed about the tube to thereby selectively inhibit expansion of the tube.

26. A method for monitoring pressure in a tube comprising:

selecting a tube which is elasticly deformable;

selecting an optical emitter and detector pair;

disposing the optical emitter and optical detector in alignment such that light emitted from the emitter strikes the detector to thereby cause the detector to produce an electrical voltage; and

disposing the tube between the emitter and detector to thereby partially obstruct the pathway of light between the emitter and detector.

27. The method of claim 26, whereby increases in pressure in the tube cause expansion of the tube, and whereby expansion of the tube selectively lowers the amount of light emitted from the optical emitter which strikes the detector.

28. The method of claim 26, wherein the method further comprises disposing the tubing inside of a generally rigid sleeve to thereby selectively inhibit expansion of the tube.

29. The method of claim 26, wherein the method further comprises disposing the tubing adjacent at least one wall to thereby selectively inhibit expansion of the tube.

30. The method of claim 26, wherein the method further comprises disposing the tubing between a pair of walls to thereby selectively inhibit expansion of the tube.

31. The method of claim 26, wherein the method further comprises disposing the tube in a channel to thereby selectively inhibit expansion of the tube.

32. The method of claim 26, wherein the method further comprises selecting a tube with a first wall thickness and having a portion of the tube with a second wall thickness which is less than the first wall thickness.