Fluid Infusion System, A Method of Assembling Such System and Drug Reservoir for Use in the System

• US 20090299288A1
• Filed: 04/19/2007
• Published: 12/03/2009
• Est. Priority Date: 04/19/2006
• Status: Active Grant

• Current Assignee: Novo Nordisk A/S
• Original Assignee: NOVO Nordisk Biotech Incorporated (Novo Nordisk A/S)
• Inventors: Sie, Gunnar Monrad, Lund, Carsten
• Granted Patent: US 8,551,045 B2
• Time in Patent Office: Days
• US Class Current: 604/151
• CPC Class Codes: A61M 2005/3151 by friction
• CPC Class Codes: A61M 5/14566 with a replaceable reservoir for receiving a piston rod of the pump
• 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 5/31515 Connection of piston with piston rod

Abstract

The present invention relates to methods and devices for providing a reduced risk of free flow from medical devices such as an infusion pump. A medicament containing reservoir is provided with a piston having a sealing portion formed by a material of a first stiffness. The piston further comprises a frictional enhancing member having one or more reservoir wall engaging portions and being at least partly made of a material having a stiffness greater than the first stiffness. By arranging the frictional enhancing member to exert a radially outwards directed force component against the cylindrical wall an increased friction is provided between the piston and the reservoir wall.

Claims

1. A fluid infusion system for infusing a medication fluid comprising:

a reservoir adapted to contain the fluid and adapted for use with a pump drive system having a linear actuation member, the reservoir comprising;

a proximal end adapted to connect to an infusion set;

an open distal end;

a cylindrical reservoir wall longitudinally extending along an axis from the proximal end to the distal end; and

a piston adapted to be slideably and frictionally mounted within the reservoir and forming a fluid-tight barrier inside the reservoir;

the piston comprising a piston body with at least one peripheral sealing portion made of a material having a first stiffness, said at least one sealing portion in sealing contact with the inside surface of the reservoir wall,

wherein the piston further comprises a friction enhancing member having one or more wall engaging portions, wherein one or more wall engaging portion is at least partially made of a material having a greater stiffness than said first stiffness, one or more wall engaging portion frictionally engaging the cylindrical wall of the reservoir and being arranged to exert a radially outwards directed force component against the cylindrical wall.

2. The fluid infusion system as defined in claim 1, wherein said friction enhancing member comprises a central section and that each wall engaging portion is coupled to the central section by a flexible shank portion bridging the wall engaging portion with the central section.

3. The fluid infusion system as defined in claim 1, wherein at least one of the wall engaging portions extends in a plane generally perpendicular to the longitudinally axis of the reservoir.

4. The fluid infusion system as defined in claim 1, wherein at least one of the wall engaging portions extends at an inclined angle with respect to a plane arranged perpendicular to the longitudinally axis of the reservoir.

5. The fluid infusion system as defined in claim 1, wherein at least one of the wall engaging portions is/are provided with an arcuate surface shaped to abut the interior wall surface of the cylindrical reservoir wall along the arcuate surface.

6. The fluid infusion system as defined in claim 1, wherein the piston body has a first external proximate side being adapted to contact the fluid and an external distal side defining an opening leading into a cavity, and that said frictional enhancing member is provided with means for fixedly retaining said frictional enhancing member inside said cavity.

7. The fluid infusion system as defined in claim 6, wherein said piston further comprises a third member adapted to releasably couple to said linear actuation member and adapted to fixedly secure said third member to at least one of said friction enhancing member and said piston body (120).

8. The fluid infusion system as defined in claim 7, wherein said linear actuation member comprises one or more protrusions and that the third member is adapted to engage said one or more protrusions.

9. The fluid infusion system as defined in claim 1, wherein said friction enhancing member is at least partly made of steel or spring steel.

10. The fluid infusion system as defined in claim 1 any of the claims 1-9, wherein the piston body and the at least one sealing portion are formed unitarily.

11. The fluid infusion system as defined in claim 1 any of the claims 1-9, wherein the piston body are made of a material having a greater stiffness than the material of the at least one sealing portion, and that the piston body and the friction enhancing member is formed unitarily.

12. The fluid infusion system as defined in claim 1 any of the claims 1-9, wherein the piston are formed by co-molding said piston body and said friction enhancing member so that said friction enhancing member is partly encapsulated by the piston body.

14. A reservoir for use in the fluid infusion system according to claim 1, the reservoir adapted to contain a fluid for infusion into the body of a patient and adapted for use with a drive system having a linear actuation member, the reservoir comprising:

a proximal end adapted to connect to an infusion set;

an open distal end;

a cylindrical reservoir wall longitudinally extending along an axis from the proximal end to the distal end; and

a piston adapted to be slideably and frictionally mounted within the reservoir and forming a fluid-tight barrier inside the reservoir;

the piston comprising a piston body with at least one peripheral sealing portion made of a material having a first stiffness, said at least one sealing portion in sealing contact with the inside surface of the reservoir wall,

wherein the piston further comprises a friction enhancing member having one or more wall engaging portions, wherein one or more wall engaging portion is at least partially made of a material having a greater stiffness than said first stiffness, the one or more wall engaging portion frictionally engaging the cylindrical wall of the reservoir and being arranged to exert a radially outwards directed force component against the cylindrical wall.

13. A method for assembling a fluid infusion system suitable for infusing a medication fluid, the method comprising:

providing a fluid infusion pump comprising a drive system having a linear actuation member;

providing a reservoir adapted to contain the fluid, the reservoir comprising;

a proximal end adapted to connect to an infusion set;

an open distal end;

a cylindrical reservoir wall longitudinally extending along an axis from the proximal end to the distal end; and

a piston adapted to be slideably and frictionally mounted within the reservoir and forming a fluid-tight barrier inside the reservoir;

the piston comprising a piston body with at least one peripheral sealing portion made of a material having a first stiffness, said at least one sealing portion in sealing contact with the inside surface of the reservoir wall; and

coupling the reservoir to the infusion pump;

wherein the piston further comprises a friction enhancing member having one or more wall engaging portions, wherein the or each wall engaging portion is at least partially made of a material having a greater stiffness than said first stiffness, the or each wall engaging portion frictionally engaging the cylindrical wall of the reservoir and being arranged to exert a radially outwards directed force component against the cylindrical wall.