Elastomeric plunger tip for a syringe

• US 4,215,701 A
• Filed: 08/21/1978
• Issued: 08/05/1980
• Est. Priority Date: 08/21/1978
• Status: Expired due to Term

• Current Assignee: Smiths Industries Medical Systems Incorporated
• Original Assignee: Concord Laboratories Incorporated
• Inventors: Raitto, Russell G.
• Primary Examiner(s): Yasko, John D.
• Application Number:
  US05/935,304
• Time in Patent Office: 715 Days
• Field of Search: 128/218 P, 128/218 PA, 128/218 R, 128/215, 128/234, 128/220, 128/221, 128/760, 128/763
• US Class Current: 600/576
• CPC Class Codes: A61B 5/15003 for venous or arterial blood
• CPC Class Codes: A61B 5/150236 Pistons, i.e. cylindrical bodies that sit inside the syringe barrel, typically with an air tight seal, and slide in the barrel to create a vacuum or to expel blood
• CPC Class Codes: A61B 5/150244 Rods for actuating or driving the piston, i.e. the cylindrical body that sits inside the syringe barrel, typically with an air tight seal, and slides in the barrel to create a vacuum or to expel blood
• CPC Class Codes: A61B 5/153 Devices specially adapted for taking samples of venous or arterial blood, e.g. with syringes

Abstract

An elastomeric plunger tip for syringes comprises a compressible, elastomeric material having a durometer of about 35 to about 75 when measured on the Shore A scale and maintains its resilience at temperatures at least as low as 0° C. The plunger tip is provided with a peripheral annular wiper lip extending axially forwardly and radially outwardly into sealing contact with the syringe barrel.

Claims

1. An elastomeric plunger tip particularly suited for a blood sampling syringe, said tip comprising a compressible, elastomeric material having a durometer of about 35 to about 75 when measured on the Shore A scale, having the ability to retain its resilience at temperatures at least as low as 0°

C., and being provided with a peripheral annular wiper lip extending axially forwardly and radially outwardly so that it forms the sole sealing element when said plunger tip if inserted in said syringe, said plunger tip providing the syringe with a self-aspirating characteristic when used to sample arterial blood while maintaining an effective seal for containing the blood sample.

2. An elastomeric plunger tip according to claim 1 wherein said material has a durometer of about 50 to 70 on the Shore A scale.

3. An elastomeric plunger tip according to claim 1 wherein said material is selected from the group consisting of natural rubber and its man-made equivalents, butyl rubbers and silicone rubbers.

4. An elastomeric plunger tip according to claim 1 wherein said material is natural gum rubber.

5. An elastomeric plunger tip according to claim 4 wherein said natural gum rubber has a durometer of about 63 on the Shore A scale.

6. An elastomeric plunger tip according to claim 1 wherein said material is butyl rubber.

7. An elastomeric plunger tip according to claim 1 wherein said material has the ability to retain its resilience at temperatures of about -40°

C.

8. A compressible and elastomeric syringe plunger tip particularly suited for a blood sampling syringe comprising a generally cylindrical main portion, an integral annular elastically deformable wiper extending peripherally radially outwardly and axially forwardly from a forward portion thereof at an acute angle to the longitudinal center axis of said tip and terminating at the outer edge thereof in a wiping edge, when used in a syringe assembly said annular wiper being the sole sealing element between said plunger tip and the syringe, said tip comprising a compressible, elastomeric material having a durometer of about 35 to about 75 when measured on the Shore A scale, having the ability to retain its resilience at temperatures at least as low as 0°

C., and being provided with a peripheral annular wiper lip extending axially forwardly and radially outwardly so that it forms the sole sealing element when said plunger tip is inserted in said syringe, said plunger tip providing the syringe with a self-aspirating characteristic when used to sample arterial blood while maintaining an effective seal for containing the blood sample.

9. A tip according to claim 8, said main portion having an end portion of reduced diameter.

10. A tip according to claim 9, said wiper and reduced diameter portion forming an annular trough in the forward face of said tip.

11. A tip according to claim 8, the edge of said wiper comprising a generally cylindrically shaped surface which extends radially outwardly and axially forwardly at a straight acute angle to the longitudinal center line of said tip.

12. A tip according to claim 11, the thickness of said wiper being tapered from the base thereof to the free end thereof so it is thicker at its base than at its end.

13. An elastomeric plunger tip according to claim 8 wherein said material has a durometer of about 50 to 70 on the Shore A scale.

14. An elastomeric plunger tip according to claim 8 wherein said material is selected from the group consisting of natural rubber and its man-made equivalents, butyl rubbers and silicone rubbers.

15. An elastomeric plunger tip according to claim 8 wherein said material is natural gum rubber.

16. An elastomeric plunger tip according to claim 15 wherein said natural gum rubber has a durometer of about 63 on the Shore A scale.

17. An elastomeric plunger tip according to claim 8 wherein said material is silicone rubber.

18. An elastomeric plunger tip according to claim 8 wherein said material has the ability to retain its resilience at temperatures of about -40°

C.

19. A tip according to claim 8, the thickness of said wiper being tapered from the base thereof to the free end thereof so that it is thicker at its base than at its end.

20. A syringe assembly according to claim 19, wherein the angle between the leading surface of said wiper and the longitudinal axis is between about 30°

and 50° and

the angle of the taper is between about 10° and

15°

.

21. A syringe assembly according to claim 8, said wiping edge comprising a plane surface of minor dimension oriented substantially parallel to the longitudinal axis of said plunger tip.

22. A syringe assembly according to claim 21 wherein said plane surface extends radially outwardly and axially forwardly at a very slight angle.

23. A syringe assembly according to claim 22 wherein the angle is about 2°

.

24. A compressible and elastomeric syringe plunger tip comprising a generally cylindrical main portion, an integral annular elastically deformable wiper extending peripherally radially outwardly and axially forwardly from a forward portion thereof at an acute angle to the longitudinal center axis of said tip and terminating at the outer edge thereof in a wiping edge, when used in a syringe assembly said annular wiper being the sole sealing element between said plunger tip and the syringe, said tip comprising a compressible, elastomeric material having a durometer of about 35 to about 75 when measured on the Shore A scale, having the ability to retain its resilience at temperatures at least as low as 0°

C., and being provided with a peripheral annular wiper lip extending axially forwardly and radially outwardly so that it forms the sole sealing element when said plunger tip is inserted in said syringe, said plunger tip having a plurality of raised portions speed circumferentially around said plunger tip and located at the rearward portion of said plunger tip, said raised portions engaging the wall of said syringe, when the plunger tip is inserted therein, to prevent canting of said plunger tip.

25. An elastomeric plunger tip according to claim 24 wherein said material has a durometer of about 50 to 70 on the Shore A scale.

26. An elastomeric plunger tip according to claim 24 wherein said material is selected from the group consisting of natural rubber and its man-made equivalents, butyl rubbers and silicone rubbers.

27. An elastomeric plunger tip according to claim 24 wherein said material is natural gum rubber.

28. An elastomeric plunger tip according to claim 27 wherein said natural gum rubber has a durometer of about 63 on the Shore A scale.

29. A self-aspirating disposable syringe assembly particularly suited because of the low force requirement for the operation thereof to be used for obtaining a blood sample from a patient comprising a barrel having a cylindrical inner wall and a plunger comprising a plunger stem and a compressible, elastomeric, generally cylindrical plunger tip of lesser diameter than the inner wall of said barrel, said plunger tip having an integral, annular, elastically deformable wiper extending peripherally radially outwardly and axially forwardly from said plunger tip at a forward portion thereof at an acute angle to the longitudinal center axis of said plunger tip and terminating at the other edge thereof in a wiping edge thereof in a wiping edge having a minimal diameter slightly in excess of the diameter of the inner wall of said barrel, thereby forming a sealing engagement with the inner wall of said barrel, said annular wiper being the sole sealing element between said plunger tip and said wall, said plunger tip comprising a compressible, elastomeric material having a durometer of about 35 to about 75 when measured on the Shore A scale, having the ability to retain its resilience at temperatures at least as low as 0°

C., and being provided with a peripheral annular wiper lip extending axially forwardly and radially outwardly so that it forms the sole sealing element when said plunger tip is inserted in said syringe, said plunger tip providing the syringe with a self-aspirating characteristic when used to sample arterial blood while maintaining an effective seal for containing the blood sample.

30. A syringe assembly according to claim 29, said wiper being tapered from the base thereof to the free end thereof so that it is thicker at its base than at its end.

31. A syringe assembly according to claim 30, wherein the angle between the leading surface of said wiper and the longitudinal axis is between about 30°

and 50° and

the angle of the taper is between about 10° and

15°

.

32. A disposable syringe assembly according to claim 29 wherein said material has a durometer of about 50 to 70 on the Shore A scale.

33. A disposable syringe assembly according to claim 29 wherein said material is selected from the group consisting of natural rubber and its man-made equivalents, butyl rubbers and silicone rubbers.

34. A disposable syringe assembly according to claim 29 wherein said material is natural gum rubber.

35. A disposable syringe assembly according to claim 34 wherein said natural gum rubber has a durometer of about 63 on the Shore A scale.

36. A syringe assembly according to claim 29, said wiping edge comprising a plane surface of minor dimension oriented substantially parallel to the longitudinal axis of said plunger tip.

37. A syringe assembly according to claim 36 wherein said plane surface extends radially outwardly and axially forwardly at a very slight angle.

38. A syringe assembly according to claim 37 wherein the angle is about 2°

.

39. A syringe according to claim 29, including a hypodermic needle secured to said barrel for insertion into the artery of a patient to withdraw a blood sample from said patient, the frictional force of said sealing engagement being of a mangitude that allows the blood pressure of said patient to move said plunger stem and tip backwardly in said barrel to draw said blood sample from said patient into said barrel.

40. A disposable syringe assembly particularly suited because of the low force requirement for the operation thereof to be used for obtaining a blood sample from a patient comprising a barrel having a cylindrical inner wall and a plunger comprising a plunger stem and a compressible, elastomeric, generally cylindrical plunger tip of lesser diameter than the inner wall of said barrel, said plunger tip having an integral, annular, elastically deformable wiper extending peripherally radially outwardly and axially forwardly from said plunger tip at a forward portion thereof at an acute angle to the longitudinal center axis of said plunger tip and terminating at the outer edge thereof in a wiping edge having a minimal diameter slightly in excess of the diameter of the inner wall of said barrel, thereby forming a sealing engagement with the inner wall of said barrel, said annular wiper being the sole sealing element between said plunger tip and said wall, said plunger tip having a plurality of raised portions spaced circumferentially around said plunger tip and located at the rearward portion of said plunger tip, said raised portions engaging said inner wall of said barrel with a minimum of frictional contact to prevent canting of said plunger tip in said barrel, said plunger tip comprising a compressible, elastomeric material having a durometer of about 35 to 75 when measured on the Shore A scale, having the ability to retain its resilience at temperatures at least as low as 0°

C., and being provided with a peripheral annular wiper lip extending axially forwardly and radially outwardly so that it forms the sole sealing element when said plunger tip is inserted in said syringe, said syringe assembly being prefilled with anticoagulant.

41. An elastomeric plunger tip according to claim 40 wherein said material has a durometer of about 50 to 70 on the Shore A scale.

42. An elastomeric plunger tip according to claim 40 wherein said material is natural gum rubber.

43. An elastomeric plunger tip according to claim 42 wherein said natural gum rubber has a durometer of about 63 on the Shore A scale.

44. An elastomeric plunger tip according to claim 40 wherein said material has the ability to retain its resilience at temperatures of about -40°

C.