Fluid pressure measurement devices

• US 5,808,203 A
• Filed: 05/12/1997
• Issued: 09/15/1998
• Est. Priority Date: 05/12/1997
• Status: Expired due to Fees

• Current Assignee: Medrad Incorporated (Bayer AG)
• Original Assignee: Medrad Incorporated (Bayer AG)
• Inventors: Hirschman, Alan D., Cowan, Kevin P., Trombley, Frederick W. III, Reilly, David M., Griffiths, David M., Nolan, William J. Jr.
• Primary Examiner(s): Dombroske, George M.
• Assistant Examiner(s): AMROZOWICZ, PAUL DOUGLAS
• Application Number:
  US08/854,411
• Time in Patent Office: 491 Days
• Field of Search: 73/700, 73/715, 73/717, 73/744-46, 73/861.11, 73/861.16, 73/862.451, 128/DIG. 1, 128/DIG. 2, 604/65, 604/657
• US Class Current: 73/700
• CPC Class Codes: A61M 5/14546 Front-loading type injectors
• CPC Class Codes: A61M 5/14566 with a replaceable reservoir for receiving a piston rod of the pump
• CPC Class Codes: A61M 5/16854 by monitoring line pressure
• CPC Class Codes: A61M 5/315 Pistons; Piston-rods; Guiding, blocking or restricting the movement of the rod or piston; Appliances on the rod for facilitating dosing ; Dosing mechanisms
• CPC Class Codes: A61M 5/31511 Piston or piston-rod constructions, e.g. connection of piston with piston-rod A61M5/5066 takes precedence
• CPC Class Codes: A61M 5/48 having means for varying, regulating, indicating or limiting injection pressure A61M5/142 takes precedence ; monitoring pressure in infusion systems A61M5/16854

Abstract

The present invention provides pressure measuring devices comprising a sensor to detect the force upon at least a portion of a contact surface of a syringe plunger during pressurization of a fluid medium within the syringe. A determination of the pressure of the fluid medium within the syringe is thereby enabled.

Claims

1. An injection system for injection of a fluid medium, the injection system comprising:

a. a syringe comprising an elongated cylindrical body and a plunger having a contact surface, the contact surface comprising a first surface that contacts the fluid medium and a second surface, substantially opposite the first surface, that does not contact the fluid medium, the plunger being movably mounted in the cylindrical body for pressurizing the fluid medium; and

b. a sensor for detecting a force upon at least a portion of the contact surface during pressurization of the fluid medium, thereby enabling determination of a pressure of the fluid medium within the syringe, the sensor being in operative connection with at least a portion of the second surface of the contact surface such that force on the at least a portion of the second surface is transmitted to the sensor during pressurization of the fluid medium.

2. The injection system of claim 1 wherein the sensor is in direct contact with the at least a portion of the second surface of the contact surface.

3. The injection system of claim 1 wherein the contact with the at least a portion of the second surface of the contact surface is via at least one intermediate member.

4. The injection system of claim 1 wherein the sensor is a load cell.

5. The injection system of claim 1 wherein the sensor detects movement of the at least a portion of the contact surface during pressurization of the fluid medium, the force upon the at least a portion of the contact surface being a function of the displacement of the at least a portion of the contact surface.

6. The injection system of claim 3 wherein the intermediate member comprises a chamber filled with a fluid in operative connection with the at least a portion of the second surface of the contact surface, an increase in pressure in the syringe causing an increase in the fluid pressure within the chamber, the sensor being in operative connection with the chamber to detect the pressure therein.

7. The injection system of claim 1 further comprising an injector, the injector having a powered drive member adapted to form an operative connection with the plunger to move the plunger in the cylindrical body, the sensor being attached to the powered drive member.

8. The injection system of claim 1 wherein the at least a portion of the contact surface is fabricated from a flexible material.

9. The injection system of claim 3 wherein the at least one intermediate member comprises a substantially solid member in operative connection with the at least a portion of the second surface of the contact surface.

10. The injection system of claim 9 wherein the at least one intermediate member is biased against the at least a portion of the second surface of the contact surface.

11. The injection system of claim 10 wherein the at least one intermediate member is biased by a spring.

12. The injection system of claim 6 wherein the fluid comprises air.

13. A method of sensing fluid pressure, comprising the following steps:

providing a syringe comprising an elongated, cylindrical body and a plunger having a contact surface, the contact surface comprising a first surface that contacts the fluid and a second surface, substantially opposite the first surface, that does not contact the fluid, the plunger being movably mounted in the cylindrical body for pressurizing the fluid;

providing a sensor for detecting a force upon at least a portion of the contact surface during pressurization of the fluid, thereby enabling determination of a pressure of the fluid within the syringe, the sensor being in operative connection with at least a portion of the second surface of the contact surface such that force on the at least a portion of the second surface is transmitted to the sensor during pressurization of the fluid; and

sensing force on at least a portion of the contact surface during pressurization of the fluid.

14. The method of claim 13 wherein the sensor is in direct contact with the at least a portion of the second surface of the contact surface.

15. The method of claim 13 wherein the contact with the at least a portion of the second surface of the contact surface is via at least one intermediate member.

16. The method of claim 13 wherein the step of sensing comprises detecting movement of the at least a portion of the contact surface during pressurization of the fluid, the force upon the at least a portion of the contact surface being a function of the displacement of the at least a portion of the contact surface.

17. A device for measurement of pressure of an injection fluid within a syringe, the device comprising:

a. a plunger comprising a contact surface having a first surface that contacts the fluid and a second surface, substantially opposite the first surface, that does not contact the fluid, the plunger adapted to be movably mounted in the syringe for pressurizing the fluid medium; and

b. a sensor for detecting the force upon at least a portion of the contact surface during pressurization of the fluid medium, thereby enabling determination of a pressure of the fluid medium within the syringe, the sensor being in operative connection with at least a portion of the second surface of the contact surface such that force on the at least a portion of the second surface is transmitted to the sensor during pressurization of the fluid medium.

18. The device of claim 17 wherein the sensor is in direct contact with the at least a portion of the second surface of the contact surface.

19. The device of claim 17 wherein the contact with the at least a portion of the second surface of the contact surface is via at least one intermediate member.