Intravenous bag and monitoring method

• US 5,098,409 A
• Filed: 01/04/1991
• Issued: 03/24/1992
• Est. Priority Date: 01/04/1991
• Status: Expired due to Term

• Current Assignee: Massachusetts Institute of Technology
• Original Assignee: Massachusetts Institute of Technology
• Inventors: Stock, Elisabeth A.
• Primary Examiner(s): Rosenbaum, C. Fred
• Assistant Examiner(s): MENDEZ, MANUEL A
• Application Number:
  US07/637,453
• Time in Patent Office: 445 Days
• Field of Search: 604/253, 604/254, 604/65-67, 604/153, 604/245, 604/246, 604/260, 604/118, 604/247, 604/185, 128/DIG. 12, 128/ DIG. 13, 340/591, 340/592, 340/603, 340/605, 340/618
• US Class Current: 604/246
• CPC Class Codes: A61M 5/1684 by detecting the amount of infusate remaining, e.g. signalling end of infusion
• CPC Class Codes: Y10S 128/12 Pressure infusion
• CPC Class Codes: Y10S 128/13 Infusion monitoring

Abstract

An intravenous bag monitoring device is connected between an IV bag which holds fluid to be delivered to a patient and a hollow IV needle which is injected into a vein of a patient. The monitoring device comprises a chamber, an inlet leading to the chamber, and an outlet leading away from the chamber. A corrugated flexible wall panel is positioned in the chamber and divides the chamber into a first section which contains fluid and a second section which does not contain fluid. A spring is positioned in the second section of the chamber. The movement of the flexible wall panel in response to changes in hydrostatic force is resisted by the spring. An elongated push rod is attached to the flexible wall, passes through the second section and forms one of two contacts required to complete a warning circuit. The other contact is on the exterior of the second chamber. As the IV bag fluid flows to the patient, the hydrostatic force in the chamber decreases causing the flexible wall panel to draw the push rod further into the chamber. A predetermined period of time before the IV bag empties a predetermined hydrostatic force threshold is reached, at which time the electrical contact on the end of the push rod outside of the chamber wall touches the electrical contact on the chamber wall. Thus, the warning circuit is completed and a signal indicating that the bag is almost empty is generated.

Claims

1. An apparatus for monitoring fluid from an IV reservoir having a first outlet tube comprising:

a chamber having a flexible wall, an inlet and an outlet, said chamber inlet connected to said IV reservoir first outlet tube,

a second outlet tube connected to said chamber outlet and adapted to be connected to an IV needle,

a spring contacting the flexible wall of the chamber and applying a force thereto,

a sensor for generating an output signal when the hydrostatic force is less than a predetermined level which indicates that the IV reservoir will be empty in a predetermined period of time, and

a warning circuit, connected to said sensor, which will generate an empty IV bag warning signal in response to said sensor output signal.

2. An apparatus, as recited in claim 1, wherein the sensor further comprises a first and a second electrical contact such that said contacts touch when the hydrostatic force is below said predetermined level.

3. An apparatus, as recited in claim 1, wherein the chamber volume is substantially constant.

4. An apparatus, as recited in claim 3, wherein the flexible wall is corrugated.

5. An apparatus, as recited in claim 1, wherein the spring is helical and contacts a central portion of the flexible wall.

6. An apparatus for monitoring fluid from an IV reservoir comprising:

an IV reservoir for delivering IV fluid to a patient;

a first tube with a proximal end and a distal end, said first tube proximal end connected to the IV bag;

a bag monitor, including a chamber with an inlet and an outlet and a flexible panel responsive to the hydrostatic force in the chamber, said chamber inlet connected to said first tube distal end;

an empty IV bag warning circuit responsive to said flexible panel, for generating a warning signal a predetermined period of time before the IV bag empties; and

a second tube with a proximal end and a distal end, said second tube proximal end connected to said chamber outlet, said second tube distal end adapted to be connected to an IV needle.

7. An apparatus, as recited in claim 6, wherein said flexible panel divides the chamber into a first section which contains fluid and a second section which does not contain fluid.

8. An apparatus, as recited in claim 7, wherein the bag monitor further comprises:

a spring, positioned in the chamber second section to resist the hydrostatic force acting on the flexible panel;

an elongated rod with a distal and proximal end, said rod distal end coupled to the flexible panel, said rod exits the chamber second section at an aperture in the chamber;

a first electrical contact on the chamber exterior near the aperture; and

a second electric contact on the rod proximal end, such that when the predetermined hydrostatic force occurs in the chamber, the first and second electrical contacts connect and activate the empty IV bag warning circuit to generate an empty IV bag warning signal.

9. An apparatus, as recited in claim 8, wherein the chamber is cubic in shape.

10. An apparatus, as recited in claim 8, wherein the flexible panel is corrugated in shape.

11. An apparatus, as recited in claim 10, wherein the flexible panel is further comprised of plastic.

12. An apparatus as recited in claim 8, wherein the spring is helical in shape.

13. An apparatus as recited in claim 12 wherein the rod is coaxial with the helical spring.

14. An apparatus, as recited in claim 8 wherein the chamber is further comprised of plastic.

15. An apparatus as recited in claim 6 further comprising a dripper with an inlet and an outlet, said dripper inlet connected to said second tube distal end, and a third tube with a distal end and a proximal end, said third tube proximal end connected to said dripper outlet, said third tube distal end adapted to be connected to an IV needle.

16. An apparatus for monitoring an IV bag fluid comprising:

(a) an IV bag for delivering fluid to a patient;

(b) a first tube with a proximal end and a distal end, said first tube proximal end connected to the IV bag;

(c) a bag monitor, coupled to the first tube, including

(i) a chamber having an inlet and an outlet;

(ii) a flexible panel, said flexible panel divides the chamber into a first section containing fluid and a second section without fluid;

(iii) a helical spring, said spring positioned between said flexible panel in the chamber second section to resist the hydrostatic force in the chamber;

(iv) an elongated rod with a distal and proximal end and coaxial with the helical spring, said rod distal end coupled to the flexible panel, said rod exits the chamber second section at an aperture in the chamber wall;

(v) an electrical warning circuit;

(vi) a first electrical contact on the chamber exterior near the aperture; and

(vii) a second electric contact on the rod proximal end, such that when the predetermined hydrostatic force occurs in the chamber, the first and second electrical contacts connect and activate the electrical warning circuit to generate an empty IV bag warning signal a predetermined period of time before the IV bag empties.

17. A method for monitoring fluid from an IV reservoir flowing from a tube connected to the IV reservoir comprising:

passing the fluid from the tube through a chamber having a flexible wall;

applying force to the exterior of the flexible wall;

generating an empty IV bag warning signal a predetermined period of time before the IV bag empties when the hydrostatic force in the reservoir falls below a predetermined threshold.

18. An apparatus for monitoring fluid from an IV reservoir coupled to an IV needle comprising:

a chamber with a diaphragm formed in a wall the interior of said chamber in fluid communication with the reservoir and the IV needle,

a sensor responsive to movement of the diaphragm for generating an output signal when the hydrostatic force on the diaphragm is less than a predetermined amount which indicates that the IV reservoir will be empty in a predetermined period of time, and for generating a warning signal when the force exceeds the amount.

19. An apparatus, as recited in claim 18, wherein the sensor comprises a spring contacting the diaphragm and first and second electrical contacts responsive to the spring such that said contacts touch when the hydrostatic force is below said predetermined level.

20. An apparatus, as recited in claim 19, wherein the diaphragm comprises an interior flexible side wall of said chamber.