Surgery – Means for introducing or removing material from body for... – Treating material introduced into or removed from body...
Reexamination Certificate
2000-12-04
2004-06-15
Hayes, Michael J. (Department: 3763)
Surgery
Means for introducing or removing material from body for...
Treating material introduced into or removed from body...
C604S230000, C604S110000
Reexamination Certificate
active
06749590
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a syringe barrel and plunger assembly having ellipsoidal configurations. More particularly, the invention relates to a syringe barrel and plunger assembly, whose plane sections are all elliptical, wherein the plunger is equipped with a plunger rod or the assembly is used in a power injector with a built-in plunger rod.
BACKGROUND OF THE INVENTION
Hypodermic syringes are well-known in the prior art comprising: a cylindrical syringe body, the horizontal cross-section of which is circular, having a fluid-receiving chamber therein; a proximal end; and a distal end. The distal end of the syringe body tapers into a tip having a bore therethrough which communicates with the fluid-receiving chamber. The top is covered by a closure means such as a stopper of a polymeric or elastomeric material, a tip cap or a membrane to prevent leakage and contamination of the fluid medication contained in the syringe barrel.
Some prior art syringes also include a needle assembly with a needle cannula having a proximal end and a distal end and a lumen extending axially therethrough. The proximal end of the needle cannula is engageable with the tip of the syringe barrel. Other prior art syringes include luer collars spaced around the tips of the syringe barrels. The luer collars include threads for engagement with corresponding threads on the proximal ends of the needle cannulas or IV sets equipped with threads.
A plunger is inserted into the open proximal end of the barrel for sliding in fluid-tight engagement with the inside wall of the fluid-receiving chamber. The plunger is equipped with a plunger rod to enable the user to exert pressure on the plunger which results in the sliding movement of the plunger in the proximal or distal directions.
Prior art syringes of all types, i.e. glass, plastic, reusable, disposable and pre-filled are fabricated with a longitudinal cylindrical configuration and a circular transverse configuration. Among the reasons for this configuration is: the familiarity of medical professionals and the general public with this traditional configuration; easy manufacturing process for round, cylindrical barrels including cutting of threads into the tip of barrels, especially glass barrels; and no orientation is required between the plungers and the barrels during assembly.
Syringes and cartridges made of glass or polymeric material for delivery of fluids to and from a patient have been proposed and utilized by the prior art, and have achieved a highly developed state. Various requirements related to specific delivery systems have also been addressed. While specific requirements of fluid delivery to and from a patient may vary, means of delivery remain essentially the same and may be characterized by the following general description of a syringe.
A syringe comprises:
a) a cylindrical barrel having a proximal end designed for receiving a plunger with or without a plunger rod removably attached to the plunger or being integral with the plunger, and a distal end adapted to mount a needle or luer connector thereon; and
b) a plunger slidably mounted in the barrel.
The plunger is inserted into the barrel at the proximal end of the syringe and thus when fluid is contained in the barrel it may be expelled by pushing the plunger in the barrel towards its distal end; or when the syringe is used to withdraw fluid from a patient, the plunger located at the distal end of the barrel is pulled towards the proximal end of the syringe thereby drawing fluid into the barrel. Since a fluid-tight seal is necessary between the plunger and the inside wall of the barrel, a resilient rubber tip is positioned on the distal end of the plunger, or typically, the plunger is made of resilient rubber-like material. Illustrative examples of prior art syringes and cartridges equipped with plunger/plunger rod units include U.S. Pat. Nos. 5,411,489; 5,531,703; 5,979,668 and 5,735,825.
In order to assure air-tight seal between the inside wall of the syringe barrel and the plunger, prior art plungers are manufactured with a larger outside diameter than the inside diameter of the syringe barrels. When the plunger is introduced into the syringe barrel, it is sufficiently compressed to provide adequate pressure between the inside wall of the syringe and the plunger to seal the interface and withstand the challenges of filling, injecting and withdrawing fluids using the syringe without leakage.
In addition to a leakage-proof seal, another requirement in the syringe/plunger combination is the chemical stability of both the syringe and the plunger. While syringes being made of glass or thermoplastic materials are sufficiently chemically inert to pharmaceutical and biological fluids contained therein, the plungers made of natural rubber or butyl rubber have some undesirable properties. The rubber contains additional chemical components such as fillers and accelerators introduced during the curing process which tend to exude to the surface of the plunger during the contact between the plunger and the fluid contained in the syringe. Such exudate is undesirable in an injection or when a biological fluid, such as blood, is withdrawn from a patient for testing purposes. The problem is further aggravated when there is a long-term storage of the content of the pharmaceutical/biological fluid in the syringe. Recognizing the problem of contamination caused by exudates from plungers made of rubber, the prior art has provided plungers made of thermoplastic materials which do not contain the additives that rubber plungers contain. However, thermoplastic materials are not as resilient as rubbers and the seals formed between thermoplastic plungers and the inside walls of syringes tend to be inadequate in some circumstances. Also, over a period of time on storage the thermoplastic plunger may achieve a compression stage wherein the outside diameter of the plunger is reduced thereby no longer capable of forming a tight seal between it and the inside wall of the syringe.
In addition to the tendency of leakage, the thermoplastic plunger does not slide smoothly in the syringe barrel and requires the exertion of excessive force on the plunger rod to move the plunger in the barrel. The exertion of excessive force on the plunger rod may result in uneven delivery of the fluid to the patient or insertion of the needle into a vein or tissue area to an undesirable depth.
In both the rubber and thermoplastic plungers a relatively large compressive force must be exerted on the plungers by the syringe barrel to provide for a tight, leakproof seal. This quality of the seal, however, makes the movement of the plunger difficult. To remedy the problem the prior art used lubricants to reduce friction and drag between the plunger and the inside surface of the syringe barrel. The use of such lubricants, however, is also undesirable with certain parenteral fluids which tend to disperse or dissolve in the parenteral fluids thereby contaminating the parenteral fluids. Attempts to avoid the use of lubricants included the use of various plunger configurations, such as plungers that were provided with one or more ribs projecting forwardly or rearwardly in the barrel to reduce the frictional drag between the plunger and the inside surface of the barrel.
While fluid tightness and sliding property have improved with these attempts, it appears that improvement in one of these properties is not quite achieved without corresponding decrease in the other property: increasing fluid tightness tends to result in decreasing sliding property, while increasing sliding property tends to result in decreasing fluid tightness.
Prior art plungers, variously designated such as sealing cap, plunger head, cup-shaped plunger, cone-shaped plunger and the like, are constructed of elastomeric materials which in the barrel of a syringe or cartridge interface both the content and the inside surface of the barrel.
In the present invention the plunger is constituted by a rigid, non-elastomeric plunger rod tip which interfaces the content of th
Bracco Diagnostics Inc.
Hayes Michael J.
Maiorino Roz
Noone M. Caragh
Peckjian Bryan M.
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