Surgery – Means for introducing or removing material from body for... – Treating material introduced into or removed from body...
Reexamination Certificate
2000-04-10
2001-03-27
Kennedy, Sharon (Department: 3763)
Surgery
Means for introducing or removing material from body for...
Treating material introduced into or removed from body...
Reexamination Certificate
active
06206859
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a self-aligning plunger rod for use in a syringe or cartridge barrel having a plunger and containing a parenteral solution therein, or in a syringe or cartridge which are empty and are to be filled with a parenteral solution by the user at the time of administration.
The present invention also relates to a plunger rod for use in a syringe or cartridge containing a parenteral solution therein intended to be dispensed from a power injector.
2. Reported Developments
Syringes and cartridges made of glass or polymeric materials for dispensing parenteral solutions or withdrawing biological fluids from a patient are well known in the prior art. They comprise a cylindrical barrel with a tapered portion at one end to which a needle or luer connector can be attached, and an open end which is stoppered by a plunger of a resilient thermoplastic or elastomeric material. The plunger serves the function of a stopper, when the barrel is filled with a fluid, or as a slidable member to expel the fluid from the barrel or withdraw a biological fluid from a patient or another source.
In order to expel fluid from the barrel or withdraw fluid into the barrel, the plunger is moved toward the distal end or the proximal end of the barrel by a plunger rod which is attachable to the plunger typically by screw threads. The user exerts a force, manually or by the use of a power injector, on the plunger rod to push or pull the plunger in the barrel. While the plunger rod does not contact the fluid in the barrel, it serves a very important function: it causes the plunger to move in an axial direction back and forth in the barrel when an external force is applied thereon.
The force applied to the plunger by the plunger rod should be perpendicular to the plunger so that the force exerted on the wall of the barrel by the plunger is uniform around the 360° of its cylindrical configuration. When the plunger rod flexes in the barrel, the direction of force on the plunger will not be uniform resulting in pressure points at certain areas of contact between the plunger and the inside wall of the barrel and, conversely, inadequate pressure points at other parts of the interface between the plunger and the inside wall of the barrel. Such pressure differences tend to allow leakage and difficulty in moving the plunger at an even rate in the barrel.
Typical prior art devices have fixed connections between plunger rods and plungers; they are either one-piece combinations of plunger rods and plungers or two-piece combinations wherein the plunger rods are threaded into the plungers. Some plungers are equipped with rigid plastic inserts having internal threads therein in order to support the elastomeric plunger heads and to engage the plunger rods and hold them in an axial orientation. Both approaches allow some movement of the plunger rods in a lateral direction which may result in leakage of the medical fluid from the syringe barrel.
Recognizing the importance of dimensional stability, the prior art has incorporated various stability enhancing means into plunger rods which include the following.
The assembly disclosed in U.S. Pat. No. 4,543,093 has a plunger rod, the central portion of which is almost as large as the inside diameter of the syringe barrel so that it will assist in keeping the plunger rod assembly concentrically aligned within the syringe barrel.
WO 93/09827 discloses a shank having a plurality of longitudinal and radially extending vanes. In one preferred embodiment the shank is provided with four vanes in an “X” pattern, while in another preferred embodiment, the shank is provided with three vanes forming a “Y” pattern.
U.S. Pat. Nos. 5,700,247 and 5,860,961 disclose plunger rods having a plurality of vanes or support ribs.
A common feature of these plunger rods is a shank extending between the distal and proximal ends of the plunger rods having vanes or support ribs thereon. The vanes or support ribs are identical with one another running longitudinally on the shank and extending radially therefrom. This feature is an improvement over typical plunger rods in that the plunger rods have limited flexibility in the lateral direction, thereby exerting pressure on the plunger surface in an axial direction. However, we have found that even limited flexibility of the plunger rods allow lateral movement of the plungers in syringe barrels. This lateral movement of the plunger rods attached to plungers can cause leakage of fluid from the syringe barrels.
An object of the present invention is to provide a plunger rod and plastic plunger insert combination which directs the force exerted on the plunger rod in an axial direction. The elastomeric plunger placed on the plastic plunger insert will exert a uniform force on the inside wall of the syringe barrel thereby preventing leakage of the fluid content from the syringe barrel.
Another object of the present invention is to provide a reinforced plunger rod in combination with a plastic plunger insert which may be used either manually or in a power injector. Reinforced plunger rods without plastic plunger inserts are disclosed in co-pending application Ser. No. 09/408,242 filed on Sep. 29, 1999 which is incorporated herein by reference.
SUMMARY OF THE INVENTION
In accordance with the present invention there is provided a plunger rod and plastic plunger insert combination having a self-aligning feature wherein the plunger rod tip fits into the socket of the plunger insert and freely glides therein. This feature allows the plunger rod tip to float in the socket of the plastic plunger insert and eliminates lateral pressure on the plastic plunger insert. The plastic plunger insert is equipped with an elastomeric plunger which may be of various configurations.
In the first embodiment of the present invention the self-aligning plunger rod and plastic plunger insert combination is provided which comprises:
a) a plunger rod having a distal end and a proximal end comprising:
longitudinal radially extending vanes;
a thumb rest at the proximal end;
a disc at the distal end; and
a plunger rod tip extending from the disc at the distal end designed to engage a plastic plunger insert, said plunger rod tip comprising a neck portion and a ball portion, the ball portion having slots therein extending axially from the neck portion;
b) a non-elastomeric plastic plunger insert comprising:
a cylindrical shaft having a distal end and a proximal end;
a cone-shaped head extending from the distal end of the cylindrical shaft having an inside surface and an outside surface;
a cavity in the cone-shaped head defined by a cylindrical rim and the inside surface of the cone-shaped head;
a plurality of tabs extending from the cylindrical rim into the cavity; and
a plurality of notches or openings between the tabs designed to receive the slotted ball portion of the plunger rod tip.
In use, the slots of the plunger rod tip are aligned with the notches or openings in the plastic insert. The ball portion of the plunger rod tip is inserted into the cavity of the plastic insert and rotated to engage the tabs of the plastic insert.
In a second embodiment of the present invention a reinforced plunger rod body is used in combination with the plunger rod tip and the plastic insert. The reinforced plunger rod body having a distal end and a proximal end comprises:
an end disc at the distal end;
a plunger rod tip extending from the end disc designed to engage a plastic plunger insert, said plunger rod tip comprising a neck portion and a ball portion, the ball portion having slots therein extending axially from the neck portion;
a thumb rest at the proximal end for facilitating exertion of external pressure on the plunger rod;
a reinforcing disc at about the longitudinal midpoint of the plunger rod;
a first pair of rectangular radially extending vanes connecting the end disc and the reinforcing disc;
a second pair of rectangular radially extending vanes connecting the reinforcing disc and the thumb rest,
a first pair of isosceles triangul
Balestracci Ernest
Niedospial Jr. John J.
Balogh Imre
Bracco Diagnostics Inc.
Kennedy Sharon
LandOfFree
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