Patient-controlled medication delivery system with overmedication prevention

• US 20020019608A1
• Filed: 08/07/2001
• Published: 02/14/2002
• Est. Priority Date: 06/16/1999
• Status: Active Grant

• Current Assignee: LMA North America Incorporated (Teleflex Incorporated)
• Original Assignee: Breg Incorporated (Breg Acquisition Corp.)
• Inventors: Mason, Bradley R., Mason, Jeffrey T.
• Granted Patent: US 6,719,728 B2
• Time in Patent Office: Days
• US Class Current: 604/133
• CPC Class Codes: A61M 5/1424 Manually operated pumps
• CPC Class Codes: A61M 5/14244 adapted to be carried by the patient, e.g. portable on the body
• CPC Class Codes: A61M 5/1456 with a replaceable reservoir comprising a piston rod to be moved into the reservoir, e.g. the piston rod is part of the removable reservoir

Abstract

A portable, patient-controlled medication delivery system includes an infusion pump and a catheter assembly. The infusion pump retains a treatment fluid and provides a drive mechanism for delivering the treatment fluid to a patient via the catheter assembly. The infusion pump includes a fluid reservoir, a dosage chamber, a displacement piston displacable within the dosage chamber, a charge flowpath providing fluid communication between the fluid reservoir and the dosage chamber, and a passive flow restrictor positioned in the charge flowpath. An elastic member is also positioned in the infusion pump to exert an elastic displacement force on the displacement piston, which expands the dosage chamber and draws the treatment fluid from the fluid reservoir into the dosage chamber at a charge flow rate controlled by the passive flow restrictor. When an opposing manual displacement force is exerted on the displacement piston, the dosage chamber contracts and discharges the treatment fluid from the dosage chamber to the treatment site.

Claims

1. An infusion pump for delivering a medical treatment fluid to a patient comprising:

a flexible fluid reservoir for storing a medical treatment fluid, said fluid reservoir having a medical treatment fluid inlet port and an inlet valve with an open position and a closed position;

a rigid dosage chamber having a fluid outlet for the medical treatment fluid;

a displacement piston displacable within said dosage chamber,

a charge flowpath providing fluid communication between said fluid reservoir and said dosage chamber, said charge flowpath including a flow restrictor; and

an elastic member connected to said displacement piston, said elastic member transitionable from a more stressed position to a less stressed position to charge said dosage chamber with the medical treatment fluid from said fluid reservoir at a charge flow rate controlled by said flow restrictor while said inlet valve remains in said closed position blocking said medical treatment fluid inlet port and transitionable from said less stressed position to said more stressed position to discharge the medical treatment fluid from said dosage chamber via said fluid outlet, wherein said elastic member displaces said displacement piston in a first direction away from said fluid outlet to expand said dosage chamber when said elastic member transitions from said more stressed position to said less stressed position, and wherein said displacement piston is displaced in a second direction toward said fluid outlet to contract said dosage chamber when said elastic member transitions from said less stressed position to said more stressed position.

2. The infusion pump of claim 1 wherein said flow restrictor is a passive device having a fixed length and a fixed cross-section, wherein said fixed length and said fixed cross-section are selected to produce the controlled charge flow rate of the medical treatment fluid through said charge flowpath into said dosage chamber.

3. The infusion pump of claim 1 wherein said flow restrictor is a continuously open length of flexible tubing.

4. The infusion pump of claim 1 wherein said fluid reservoir is a substantially inelastic bladder.

5. The infusion pump of claim 1 wherein said elastic member is a spring.

6. A medication delivery system comprising:

an infusion pump including,

a flexible fluid reservoir for storing a treatment fluid, said fluid reservoir having a treatment fluid inlet port and an inlet valve with an open position and a closed position,

a rigid dosage chamber having a fluid outlet for the treatment fluid,

a displacement piston slidably displacable within said dosage chamber,

a charge flowpath providing fluid communication between said fluid reservoir and said dosage chamber, said charge flowpath including a flow restrictor; and

an elastic member connected to said displacement piston, said elastic member transitionable from a more stressed position to a less stressed position to charge said dosage chamber with said treatment fluid from said fluid reservoir at a charge flow rate controlled by said flow restrictor while said inlet valve remains in said closed position blocking said treatment fluid inlet port and transitionable from said less stressed position to said more stressed position to discharge said treatment fluid from said dosage chamber via said fluid outlet, wherein said elastic member displaces said displacement piston in a first direction away from said fluid outlet to expand said dosage chamber when said elastic member transitions from said more stressed position to said less stressed position, and wherein said displacement piston is displaced in a second direction toward said fluid outlet to contract said dosage chamber when said elastic member transitions from said less stressed position to said more stressed position; and

a medicine catheter having first and second ends, wherein said medicine catheter is in fluid communication with said fluid outlet of said dosage chamber, and wherein said first end of said medicine catheter is positionable in a treatment site of a patient to deliver the treatment fluid to the treatment site.

7. The medication delivery system of claim 6 wherein said flow restrictor is a passive device having a fixed length and a fixed cross-section, wherein said fixed length and said fixed cross-section are selected to produce the controlled charge flow rate of the medical treatment fluid through said charge flowpath into said dosage chamber.

8. The medication delivery system of claim 6 wherein said flow restrictor is a continuously open length of flexible tubing.

9. The medication delivery system of claim 6 wherein said fluid reservoir is a substantially inelastic bladder.

10. An infusion pump for delivering a medical treatment fluid to a patient comprising:

a fluid reservoir;

a dosage chamber;

a displacement piston displacable within said dosage chamber;

a charge flowpath providing fluid communication between said fluid reservoir and said dosage chamber, said charge flowpath including a passive flow restrictor; and

an elastic member connected to said displacement piston, said elastic member transitionable from a more stressed position to a less stressed position to charge said dosage chamber with the medical treatment fluid from said fluid reservoir at a charge flow rate controlled by said passive flow restrictor and transitionable from said less stressed position to said more stressed position to discharge the medical treatment fluid from said dosage chamber, wherein said elastic member displaces said displacement piston in a first direction to expand said dosage chamber when said elastic member transitions from said more stressed position to said less stressed position, and wherein said displacement piston is displaced in a second direction to contract said dosage chamber when said elastic member transitions from said less stressed position to said more stressed position.

11. The infusion pump of claim 10 wherein said passive flow restrictor has a fixed length and a fixed cross-section, wherein said fixed length and said fixed cross-section are selected to produce the controlled charge flow rate of the medical treatment fluid through said charge flowpath into said dosage chamber.

12. The infusion pump of claim 10 wherein said passive flow restrictor is a continuously open length of flexible tubing.

13. The infusion pump of claim 10 wherein said fluid reservoir is a substantially inelastic bladder.

14. The infusion pump of claim 10 wherein said elastic member is a spring.

16. The infusion pump of claim 15 wherein said passive flow restrictor is a continuously open length of flexible tubing.

17. The infusion pump of claim 15 wherein said fluid reservoir is a substantially inelastic bladder.

19. The method of claim 18 wherein said controlled charge flow rate corresponds to a desired dosage rate of said medical treatment fluid to a patient.

20. The method of claim 18 wherein said controlled charge flow rate is substantially constant.

21. The method of claim 18 wherein said displacement piston is displaced by transitioning an elastic member connected to said displacement piston from a more stressed position to a less stressed position.

22. The method of claim 18 wherein displacement of said displacement piston creates a void in said dosage member of extremely reduced pressure relative to said fluid reservoir.

23. The method of claim 18 wherein displacement of said displacement piston creates a void constituting a near total vacuum.

24. The method of claim 18 wherein said fluid reservoir is maintained at substantially ambient atmospheric pressure.

15. An infusion pump for delivering a medical treatment fluid to a patient comprising:

a fluid reservoir;

a dosage chamber;

a displacement piston displacable within said dosage chamber;

a charge flowpath providing fluid communication between said fluid reservoir and said dosage chamber, said charge flowpath including a passive flow restrictor having a fixed length and a fixed cross-section; and

an elastic member connected to said displacement piston, said elastic member transitionable from a more stressed position to a less stressed position to charge said dosage chamber with the medical treatment fluid from said fluid reservoir at a charge flow rate controlled by said passive flow restrictor, wherein said fixed length and said fixed cross-section are selected to produce the controlled charge flow rate.

18. A method for charging a dosage chamber of an infusion pump with a liquid medical treatment fluid comprising:

providing a fluid reservoir containing a liquid medical treatment fluid and a dosage chamber containing a displacement piston;

providing fluid communication between said fluid reservoir and said dosage chamber via a charge flowpath, said charge flowpath including a passive flow restrictor having a fixed length and a fixed cross-section;

displacing said displacement piston in said displacement chamber to create a positive pressure differential between said fluid reservoir and said dosage chamber; and

driving said medical treatment fluid from said fluid reservoir through said charge flowpath into said dosage chamber by said positive pressure differential at a charge flow rate controlled by said passive flow restrictor, wherein said fixed length and said fixed cross-section are selected to produce said controlled charge flow rate.