Pressure measurement device

• US 6,033,366 A
• Filed: 10/14/1997
• Issued: 03/07/2000
• Est. Priority Date: 10/14/1997
• Status: Expired due to Term

• Current Assignee: Data Sciences U K Limited (International Business Machines Corporation)
• Original Assignee: Data Sciences U K Limited (International Business Machines Corporation)
• Inventors: Brockway, Brian P., Mills, Perry Alton, Moench, Mel Murray
• Primary Examiner(s): O'Connor, Cary
• Assistant Examiner(s): CARTER, RYAN CHRISTOPHER
• Application Number:
  US08/950,315
• Time in Patent Office: 875 Days
• Field of Search: 600/435, 600/485-486, 600/488, 600/505, 600/561, 600/585, 604/43, 604/264, 604/280, 604/282-283
• US Class Current: 600/486
• CPC Class Codes: A61B 5/0215 by means inserted into the body catheters A61M25/00
• CPC Class Codes: A61B 5/031 Intracranial pressure
• CPC Class Codes: A61M 2025/0003 having an additional lumen transmitting fluid pressure to the outside for measurement

Abstract

A device measures pressures in animals and humans and includes a pressure transmission catheter (PTC) filled with a pressure transmitting medium and implantable in an area in having a physiological pressure. A transducer conmmunicates with the pressure transmitting medium to provide a pressure signal representing variations in the physiologic pressure on electrical wires. A connecting catheter carries the electrical wires to signal processing and telemetry circuitry, which transmits a telemetry signal representing the pressure signal to a receiver external to the animal or human. A housing holds the signal processing and telemetry circuitry, but the transducer is remote from the housing. The device is particularly useful in measuring venous pressure, pulmonary pressure, bladder pressure, or intracranial pressure without significant head pressure artifact and with a sufficient dynamic response. One embodiment of the PTC includes a multi-durometer stem.

Claims

1. An apparatus for measuring physiological pressure comprising:

a pressure transmission catheter filled with a pressure transmitting medium and implantable in an area having a physiological pressure;

a connecting catheter carrying electrical wires;

a transducer coupled to the electrical wires and in communication with the pressure transmitting medium to provide a pressure signal representing variations in the physiologic pressure on the electrical wires;

signal processing and telemetry circuitry coupled to the electrical wires to receive the pressure signal and provide a telemetry signal representing the pressure signal; and

a housing holding the signal processing and telemetry circuitry, wherein the transducer is remote from the housing.

2. The apparatus of claim 1 wherein the pressure transmission catheter includes:

a lumen filled with the pressure transmitting medium;

a inner layer material surrounding the lumen; and

an outer layer material surrounding the inner layer material, wherein the outer layer material has a different hardness than the inner layer material.

3. The apparatus of claim 2, wherein the inner layer material is harder then the outer layer material.

4. An apparatus for measuring physiological pressure comprising:

a pressure transmission catheter filled with a pressure transmitting medium and having a distal tip for placement in an area having a physiological pressure and a proximal end;

a connecting catheter carrying electrical wires;

a transducer coupled to the electrical wires and in communication with the pressure transmitting medium at the proximal end of the pressure transmission catheter to provide a pressure signal representing variations in the physiologic pressure on the electrical wires;

signal processing circuitry coupled to the electrical wires to process the pressure signal; and

wherein a distance between the distal tip and the proximal end of the pressure transmission catheter is sufficiently short to avoid significant head pressure artifact and provide sufficient dynamic response yet sufficiently long to accommodate surgical limitations and tolerance concerns in applications for measuring physiological pressures where, if a length of the pressure transmission catheter was the combined length of the pressure transmission catheter and the connecting catheter, there would be a significant head pressure artifact and/or an insufficient dynamic response.

5. The apparatus of claim 4, wherein the pressure transmission catheter includes:

a lumen filled with the pressure transmitting medium;

a inner layer material surrounding the lumen; and

an outer layer material surrounding the inner layer material, wherein the

outer layer material has a different hardness than the inner layer material.

6. The apparatus of claim 5, wherein the inner layer material is harder then the outer layer material.

7. An apparatus for measuring physiological pressure comprising:

a pressure transmission catheter filled with a pressure transmitting medium and having a distal tip for placement in an area having a physiological pressure and a proximal end, wherein a distance between the distal tip and the proximal end is sufficiently short to avoid significant head pressure artifact and provide sufficient dynamic response yet sufficiently long to accommodate surgical limitations and tolerance concerns;

a connecting catheter carrying electrical wires;

a transducer coupled to the electrical wires and in communication with the pressure transmitting medium at the proximal end of the pressure transmission catheter to provide a pressure signal representing variations in the physiologic pressure on the electrical wires;

signal processing circuitry coupled to the electrical wires to process the pressure signal; and

a housing holding the signal processing circuitry, wherein the transducer is remote from the housing.

8. The apparatus of claim 7, wherein the pressure transmission catheter includes:

a lumen filled with the pressure transmitting medium;

a inner layer material surrounding the lumen; and

an outer layer material surrounding the inner layer material, wherein the

outer layer material has a different hardness than the inner layer material.

9. The apparatus of claim 8, wherein the inner layer material is harder then the outer layer material.

10. A pressure transmitting catheter implantable in an area having a physiological pressure, the pressure transmitting catheter comprising:

a lumen filled with a pressure transmitting medium;

a first layer material surrounding the lumen; and

at least one additional layer of material surrounding the first layer material, wherein the at least one additional layer of material has at least one material with a different hardness than the first layer material.

11. The pressure transmitting catheter of claim 10 wherein the first layer material is harder than at least one material of the at least one additional layer of material.

12. The pressure transmitting catheter of claim 10, wherein a transition between the first layer material and the at least one additional layer of material is a sharp transition.

13. The pressure transmitting catheter of claim 10, wherein a transition between the first layer material and the at least one additional layer of material is a gradient transition.

14. The pressure transmitting catheter of claim 10, wherein the harder one of the first and at least one additional layer materials essentially determines the frequency response of the pressure transmitting catheter and the softer one of the first and at least one additional layer materials makes the pressure transmitting catheter more flexible and kink resistant.

15. The pressure transmitting catheter of claim 10, wherein the first layer material comprises 72 D urethane and the at least one additional layer material comprises 80 A urethane.

16. The pressure transmitting catheter of claim 10, wherein an outer diameter of the pressure transmitting catheter is in a range from approximately 0.014 to approximately 0.022 inches, the inner diameter of the lumen in less than approximately 0.008 inches, and the combined thickness of the first layer material and at least one additional layer of material is less than approximately 0.005 inches.

17. The pressure transmitting catheter of claim 16, wherein the thickness of the first material is less than approximately 0.002 inches.

18. The pressure transmitting catheter of claim 10, wherein the first layer material comprises a radiopaque material.

19. The pressure transmitting catheter of claim 18, wherein the first layer material comprises an approximately 20-30% barium filled urethane.

20. The pressure transmitting catheter of claim 18, wherein the at least one additional layer of material comprises non-thrombogenic material.

21. The pressure transmitting catheter of claim 10, wherein the at least one additional layer comprises one layer of material with a hardness different from the hardness of the first layer.

22. An apparatus for measuring physiological pressure comprising:

a pressure transmission catheter implantable in an area having a physiological pressure and including;

a lumen filled with a pressure transmitting medium,

a inner layer material surrounding the lumen, and

an outer layer material surrounding the inner layer material, wherein the outer layer material has a different hardness than the inner layer material;

a connecting catheter carrying electrical wires;

a transducer coupled to the electrical wires and in communication with the pressure transmitting medium to provide a pressure signal representing variations in the physiologic pressure on the electrical wires;

signal processing circuitry coupled to the electrical wires to process the pressure signal; and

a housing holding the signal processing circuitry, wherein the transducer is remote from the housing.

23. The apparatus of claim 22, wherein the inner layer material is harder then the outer layer material.

24. The apparatus of claim 22, wherein the pressure transmission catheter has a distal tip for placement in the area having a physiological pressure and a proximal end coupled to the transducer, and wherein a distance between the distal tip and the proximal end is sufficiently short to avoid significant head pressure artifact and provide sufficient dynamic response yet sufficiently long to accommodate surgical limitations and tolerance concerns.

25. An apparatus for measuring physiological pressure comprising:

a pressure transmission catheter filled entirely with a pressure transmitting gel and implantable in an area having a physiological pressure;

a connecting catheter carrying electrical wires;

a transducer coupled to the electrical wires and in communication with the pressure transmitting gel to provide a pressure signal representing variations in the physiologic pressure on the electrical wires;

signal processing and telemetry circuitry coupled to the electrical wires to receive the pressure signal and provide a telemetry signal representing the pressure signal; and

a housing holding the signal processing and telemetry circuitry and the transducer.

26. The apparatus of claim 25, wherein the pressure transmission catheter includes:

a lumen filled with the pressure transmitting gel;

a inner layer material surrounding the lumen; and

an outer layer material surrounding the inner layer material, wherein the

outer layer material has a different hardness than the inner layer material.

27. The apparatus of claim 26, wherein the inner layer material is harder then the outer layer material.

28. An apparatus for measuring physiological pressure comprising:

a pressure transmission catheter filled with a pressure transmitting medium and implantable in an area having a physiological pressure, the pressure transmission catheter including;

a lumen filled with the pressure transmitting medium,

a first layer of a first material surrounding the lumen, and

at least one additional layer that includes at least one material that is different from the

first material, the at least one additional layer surrounding the first layer, wherein

the first material has a different hardness than at least one material in the at least

one additional layer;

a connecting catheter carrying electrical wires;

a transducer coupled to the electrical wires and in communication with the pressure transmitting medium to provide a pressure signal representing variations in the physiologic pressure on the electrical wires; and

signal processing and telemetry circuitry coupled to the electrical wires to receive the pressure signal and provide a telemetry signal representing the pressure signal.

29. The apparatus of claim 28, wherein the pressure transmitting medium comprises a gel.

30. The apparatus of claim 28, wherein the pressure transmitting medium comprises a gel and a low-viscosity liquid.

31. The apparatus of claim 28, wherein the pressure transmitting medium comprises a slidable plug and a low-viscosity liquid.

32. The apparatus of claim 28, wherein the first layer material is harder than at least one material in the at least one additional layer.

33. The apparatus of claim 28, wherein the at least one additional layer comprises one layer of a material that is harder than the material of the first layer.

34. An apparatus for measuring physiological pressure comprising:

a pressure transmission catheter filled with a pressure transmitting medium and having a distal tip for placement in an area having a physiological pressure and a proximal end, wherein a distance between the distal tip and the proximal end is sufficiently short to avoid significant head pressure artifact and provide sufficient dynamic response yet sufficiently long to accommodate surgical limitations and tolerance concerns;

the pressure transmission catheter including;

a lumen filled with the pressure transmitting medium,

a first layer of a first material surrounding the lumen, and

at least one additional layer that includes at least one material that is different from the first material, the at least one additional layer surrounding the first layer, wherein the first material has a different hardness than at least one material in the at least one additional layer;

a connecting catheter carrying electrical wires;

a transducer coupled to the electrical wires and in communication with the pressure transmitting medium at the proximal end of the pressure transmission catheter to provide a pressure signal representing variations in the physiologic pressure on the electrical wires; and

signal processing circuitry coupled to the electrical wires to process the pressure signal.

35. The apparatus of claim 34, wherein the pressure transmitting medium comprises a gel.

36. The apparatus of claim 34, wherein the pressure transmitting medium comprises a gel and a low-viscosity liquid.

37. The apparatus of claim 34, wherein the pressure transmitting medium comprises a slidable plug and a low-viscosity liquid.

38. The apparatus of claim 34, wherein the first layer material is harder than at least one material in the at least one additional layer.

39. The apparatus of claim 34, wherein the at least one additional layer comprises one layer of a material that is harder than the material of the first layer.