TITLE OF THE INVENTION

Needle Having Optimum Grind for Reduced Insertion Force.

BACKGROUND OF THE INVENTION AND PRIOR ART

This invention relates to medical devices, and more particularly to an introducer needle arranged to facilitate membrane penetration and installation of a cannula or catheter within the membrane.

The delivery of medication or other fluids is often accomplished through a cannula or catheter that is typically placed either subcutaneously or intravenously. For subcutaneous delivery of fluids, the use of an infusion set or injection port reduces the need to constantly puncture the skin and provides a method of temporarily detaching the fluid line for activities such as dressing or bathing. Infusion sets typically include a cannula and an introducer needle that extends through the cannula. A self-adhesive pad is often used to secure the cannula against movement once installed. A manual inserter is often used to install the fusion set. The manual inserter typically includes a housing and a spring-loaded sliding mechanism located in the housing to which the infusion set is temporarily connected. In use, the user typically grasps the inserter housing with one hand while pinching a fold of skin between the thumb and forefinger of the other hand. The sliding mechanism is then released to force the introducer needle and the outer end of the cannula into the fold of skin. The introducer needle is then removed, leaving the cannula installed in the subcutaneous layer. The cannula can then be secured against movement. A tubing from a fluid supply source, such as an insulin pump, can be connected to the cannula housing to deliver insulin or other substances to the subcutaneous layer through the cannula.

The introducer needle is typically constructed of a hollow, metallic tube with one end ground at an angle to form a cutting tip that is offset from a central axis of the tube. Insertion of the introducer needle into the skin typically requires a relatively high insertion force, due at least in part to the offset nature of the cutting tip. The combination of relatively high insertion force and the offset nature of the tip may create a bending moment about the introducer needle during insertion. When the bending moment is relieved, such as when the introducer needle pierces the skin, the surrounding tissue may be damaged and discomfort may be increased as the introducer needle attempts to spring back to its original shape.

In addition, burr formation is often prevalent during manufacture of the angle ground hollow introducer needle. The removal of such burrs can be time consuming and difficult.
Furthermore, during assembly of an infusion set, the offset cutting tip of the introducer needle can contact and damage the inner side wall of the cannula. Thus, great care is needed to ensure that the introducer needle and cannula are properly aligned during insertion of the introducer needle through the cannula.

The some of the documents listed below appears to be close prior art to the instant invention. Further, each of the prior art is explained in brief along with the limitations, and disadvantages.

(i) US5057082, (ii) EP0378095, (iii) US3742958, (iv) US3994287, and (v) US4513747
The document (i) U.S. Patent Application US5057082 relates to surgical instruments and, more particularly, to a trocar assembly which may also be useful for endoscopic procedures.
This reference discloses a trocar assembly including a trocar tube or cannula having the "conventional" operating head and a trocar actuator or mandrel releasably supported within the tube. The head may be of conventional fabrication including a valve for the introduction of fluid or gaseous material into the cavity being pierced, or other devices such as viewing eye pieces in the event the trocar assembly is to be utilized as an endoscopic diagnostic instrument. The trocar actuator or mandrel is preferably a unitary, one-piece structure made of polymeric material, either thermoplastic or thermoset and from a process which results in the final manufacture as a single article of manufacture. Examples of suitable polymeric materials include, without limitation, nylons, polyacetals, and polycarbonates. The piercing and cutting end preferably has a diameter slightly larger than that for the shank 18 and provides clearance space within the cannula.

The document (ii) European Patent Application EP0378095 relates to the instrument set for puncturing a body cavity, in particular for suprapubic bladder drainage. The citation discloses the preferred embodiment which consists of a longitudinally separable sleeve in which a retractable, cylindrical trocar fits whose end piece projects beyond the distal edge of the sleeve and is provided with a triangularly cut, closed tip. According to the invention, the distal edge of the sleeve is bevelled in downwards towards the cylindrical circumference of the trocar and the cut tip is formed at the distal end of a conical dilation zone of the end piece. The trocar is hollow. Behind the dilation zone and in front of the distal edge of the sleeve, it has a side hole opening into the longitudinal channel of the trocar, and it is provided at the proximal end with an outlet. Such an instrument set is characterized by low puncture forces and by a reduced risk of injury to the vessels of the wall of the body cavity during penetration.

The document (iii) U.S. Patent Application US3742958 relates to improvements in surgical and medical apparatus and more particularly to apparatus for inserting a catheter into a body cavity for establishing a fluid transmission path thereto. This reference discloses the trocar has along its length a reduced diameter between its tip and base. The trocar may be formed of a single piece of material. The tip of the trocar has a four sided point of medium bevel formed on it to ease insertion through the abdominal tissues. The particular type point formed is of interest, since it is not intended as truly a cutting edge; rather, it is designed for spreading the tissues whereby when the instrument and catheter are withdrawn from the wound the tissues contract readily without producing a constantly draining fistula.

This invention is of particularly beneficial use following a surgical repair on the bladder known as an anterior colporrhaphy, commonly accompanied by posterior colporrhapy and vaginal hysterectomy, before inserting any vaginal packing.

The document (iv) U.S. Patent Application US3994287 relates to a surgical instrument for piercing a body cavity and for thereafter providing a means for communicating inside the cavity, e.g., to drain or deliver fluids or to perform other surgical acts. This reference discloses the trocar is particularly intended for use during laparoscopic tubal cauterization. In this type of surgical intervention, the abdominal cavity of a patient is first insufflated with C02. A trocar is then used to pierce the cavity wall. The puncturing element of the trocar is subsequently disassociated with the cannula, a portion of which is retained inside the cavity.

The trocar comprises, in combination: a sharp-pointed puncturing instrument made of a bio-compatible plastic material; a cannula also made of a bio-compatible plastic material and having a flange at one end thereof; a flexible insulating member secured in the cannula flange and in constricting engagement with the puncturing instrument; and a collar tightly fitted in the cannula flange and securing the flexible member in place allowing, however, a portion of the member to flex in the longitudinal axis of the cannula as the puncturing instrument is introduced in the cannula or disassociated therefrom.
The puncturing instrument of the trocar includes an elongated shank portion terminating at one extremity thereof with a sharp pointed end and at the other extremity thereof with a finger knob. End has a pyramidal shape defining three spaced cutting edges diverging from a tip and defining three smooth surfaces.

The document (v) U.S. Patent Application US4513747 relates to surgical needles and in particular to an improved surgical needle for suturing through calcified tissue, cartilage or bone.
This reference discloses a surgical needle. Needle includes a body portion and a cutting portion has a curved axis which defines a reference plane. The needle may optionally be curved in a direction opposite to that of the needle and will have a curved axis which nevertheless lies in the same reference plane as that defined by axis. A main cutting edge is formed in a conventional manner at the bottom of said cutting portion by the intersection of a first substantially planar surface and a second substantially planar surface. Thus it can be seen that main cutting edge lies in the reference plane. Secondary cutting edges are formed by the intersection of a third substantially planar surface, with planar surfaces respectively.

Cutting portion includes an end portion and a tip, the longitudinal axis of the needle being designated. Substantially planar surfaces are formed at the bottom of end portion, thus creating three additional cutting edges. It will be noted that cutting edge constitutes an extension of cutting edge and said cutting edge extends to the tip which lies at the intersection of the reference plane and planar surface. It will also be noted that the angle "a" between cutting edges, is necessarily greater than the angle "b" between cutting edges.

Whereas the present invention relates to an introducer needle for penetrating a membrane comprises a solid body portion having a central axis and a tip portion extending from the solid body portion. The tip portion includes a plurality of intersecting wedge surfaces that converge toward a common insertion point from the solid body portion. Preferably, the common insertion point is coincident with the central axis of the solid body portion. The tip portion also includes a plurality of cutting edges formed at intersections of the wedge surfaces. The cutting edges converge toward the common insertion point from the solid body portion. With this arrangement, insertion of the introducer needle into the membrane causes even cutting and separation of the membrane around the introducer needle.

The introducer needle 18 includes a body portion 40 and a tip portion 42 that is integrally formed with, and extends from, the body portion 40. Preferably, the body portion 40 and tip portion 42 are of solid construction.

The cutting edges 60, 62 and 64 preferably converge toward the common insertion point 52 from the solid body portion 40 and are preferably circumferentially spaced about the central axis 54 at an angle B of approximately 120 degrees. Since the cutting edges extend along the intersection of the wedge faces, they also extend or slope from the solid body portion 40 to the common insertion point or central axis 54 at an angle A in the range of approximately 5-30 degrees, and more preferably at an angle A of approximately 15 degrees. In this manner, the length of each cutting edge 60,62 and 64 can be less than a cutting length of the prior art angle ground hollow needle to thereby reduce material costs.

The introducer needle 18 is preferably constructed from a solid rod or bar of material, such as stainless steel, by cutting the rod or bar to a predetermined length, then grinding or otherwise forming one end of the rod or bar to form the tip portion 42.

The concentric location of the insertion point 52 together with the symmetrically spaced cutting edges 60, 62 and 64 facilitate insertion of the introducer needle 18 into the skin with a concentric coaxial force. This coaxial force has substantially no bending component, as in the prior art angle ground hollow needles. The three cutting edges 60, 62 and 64 cooperate with the concentric insertion point 52 and the wedge faces 46, 48 and 50 to minimize skin displacement during needle insertion while assuring a clean cut through the tissue. In addition, the solid construction of the introducer needle 18 gives added strength over prior art hollow body constructions.

Based on the above explanation, herein the present invention provides the inserter needle with wedge surfaces which allow the needle to pierce the body and move smoothly into the membrane during needle insertion which helps in clean cut and minimize skin displacement and accidental damages to the tissue.

As in the case of prior arts, which requires the combination of relatively high insertion force and the offset nature of the cutting tip may create a bending moment about the introducer needle during insertion, when the bending moment is relieved such as when the introducer needle pierces he skin, the surrounding tissue may be damaged and discomfort may be increased as the introducer needle attempts to spring back to its original shape. Thus, by creating wedge surfaces in the insertion needle can generally avoid the discomfort and inadvertent damages to the tissues.

Secondly, the wedge faces of cutting edge are equally distributed and the common insertion point is preferably coincide with central axis of the introducer needle which facilitate insertion of the introducer needle 18 into the skin with a concentric coaxial force. This coaxial force has substantially no bending component, as in the prior art angle ground hollow needles.

And finally, the length of the each cutting edge is less than the prior arts which provides us to cut pierces the skin to required length which is not in the case of prior art.
In particular, documents (1) to (v) fails to disclose anything related to wedge surfaces, the common insertion point is preferably coincide with central axis of the introducer needle and length of the needle which is less than prior art length.

Thus none of the prior arts alone or in combination disclose the needle and the infusion set of the instant invention. Hence, the instant invention is developed to overcome the potential limitations of the prior arts and provide better and efficient needle.

OBJECTS OF INVENTION

The primary object of the instant invention is to develop an infusion set (10) comprising: a cannula housing (16); a cannula (14) extending from the cannula housing (16); and an introducer needle (18) extending through at least a portion of the cannula (14).

Another object of the present invention is to develop an introducer needle (18) comprising: a solid body portion (40) having a central axis (54); a solid tip portion (42) extending from the solid body portion (40),
Another object of the present invention is to develop a solid tip portion (42) comprising: a common insertion point (52) that is coincident with the central axis (54); a plurality of wedge surfaces (46, 48 and 50) extending from the solid body portion (40) and converging toward the common insertion point (52), each wedge surface forming an intersection with an adjacent wedge surface; and a plurality of cutting edges (60, 62 and 64) formed at the intersections of the wedge surfaces, the cutting edges (60, 62 and 64) converging toward the common insertion point (52); wherein insertion of the introducer needle (18) into the membrane causes even cutting and separation of the membrane around the introducer needle.

STATEMENT OF THE INVENTION

According to one aspect of the invention, an infusion set (10) comprising: a cannula housing (16); a cannula (14) extending from the cannula housing (16); and an introducer needle (18) extending through at least a portion of the cannula (14), the introducer needle (18) comprising: a solid body portion (40) having a central axis (54); a solid tip portion (42) extending from the solid body portion (40), the solid tip portion (42) comprising: a common insertion point (52) that is coincident with the central axis (54); a plurality of wedge surfaces (46, 48 and 50) extending from the solid body portion (40) and converging toward the common insertion point (52), each wedge surface forming an intersection with an adjacent wedge surface; and a plurality of cutting edges (60, 62 and 64) formed at the intersections of the wedge surfaces, the cutting edges (60, 62 and 64) converging toward the common insertion point (52); wherein insertion of the introducer needle (18) into the membrane causes even cutting and separation of the membrane around the introducer needle.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The foregoing summary, as well as the following detailed description of preferred embodiments of the invention, will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, there is shown in the drawings embodiments which are presently preferred. It should be understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown. In the drawings:

FIG. 1 is a front perspective view of an inserter assembly incorporating an infusion set
with an introducer needle in accordance with the present invention;

FIG.2 is an enlarged perspective view of a portion of the introducer needle and cannula;

FIG. 3 is a side elevational view of a portion of the introducer needle;

FIG. 4 is a front elevational view of the introducer needle; and

FIG. 5 is a front elevational view of an introducer needle in accordance with a further embodiment of the invention.

It is noted that the drawings are intended to represent only typical embodiments of the invention and therefore should not be construed as limiting the scope thereof. The invention will now be described in greater detail with reference to the drawings, wherein like parts throughout the drawing figures are represented by like numerals.

DETAILED DESCRIPTION OF THE INVENTION

Certain terminology may be used in the following description for convenience only and is not limiting. The words "left," "right," "upper," and "lower" designate directions in the drawings to which reference is made. The words "inwardly" and "outwardly" refer to directions toward and away from, respectively, the geometric center of the needle and designated parts thereof. The terminology includes the words above specifically mentioned, derivatives thereof, and words of similar import.

Referring now to the drawings and to FIG. 1 in particular, an infusion set 10 in accordance with the present invention is shown temporarily positioned on an inserter assembly 12 for installation in the subcutaneous skin layer of a user.

The infusion set 10 includes a cannula 14 extending from a generally hollow cannula housing 16 and an introducer needle 18 extending through the cannula 14 and into the cannula housing 16. The cannula 14 is preferably constructed of a fluoropolymer material, such as Teflon, or other inert material. An adhesive-backed pad 20 is preferably attached to the cannula housing 16 with the adhesive layer (not shown) facing away from the cannula housing 16. A portion of the pad 20 is shown broken away in FIG. I to more clearly illustrate the introducer needle 18 and cannula 14 extending underneath the housing. It will be understood that the infusion set 10 is not limited to the low-profile type, but may be arranged to insert the introducer needle 18 and cannula 14 at different angles, including perpendicular, to the skin surface.

The inserter 12 includes an inserter housing 22 with an angled alignment guide 24 formed therewith so that the infusion set 10 can be inserted into the skin at a predetermined angle. The inserter 12 also includes a spring-loaded slide assembly 26 that is biased toward a forward position as shown, and is retractable to a rearward or cocked position. A locking mechanism 28 is adapted to hold the slide assembly 26 in the cocked position, and an actuating button 30 is operatively associated with the locking mechanism 28 for releasing the slide assembly 26. A locking lever 32 can also be provided for preventing inadvertent depression of the actuating button 30, and thus inadvertent release of the slide assembly 26. Further details of the inserter assembly can be found in copending U. S. Patent Application Publication No. 2002/0077599 filed on December 18, 2001, the disclosure of which is hereby incorporated by reference. It will be understood that the infusion set 10 can be used with inserters of different configurations, or can be used without an inserter.

With reference now to FIGS. 2-4, the introducer needle 18 includes a body portion 40 and a tip portion 42 that is integrally formed with, and extends from, the body portion 40. Preferably, the body portion 40 and tip portion 42 are of solid construction. As shown, the body portion 40 is circular in cross section, but may be configured with other cross sectional shapes, such as triangular, square, oval, and so on.

The tip portion 42 preferably includes a plurality of substantially planar wedge faces, such as first wedge face 46; second wedge face 48 and third wedge face 50 that converge toward a common insertion point 52 from the body portion 40. The common insertion point 52 is preferably coincident with a central axis 54 of the introducer needle 18. Preferably, the wedge faces extend from the solid body portion 40 to the central axis 54 at an angle A in the range of approximately 5-30 degrees, and more preferably at an angle A of approximately 15 degrees. As shown, the first and second wedge faces 46 and 48 intersect to form a first cutting edge 60, the first and third wedge faces 46 and 50 intersect to form a second cutting edge 62, and the second and third wedge faces 48 and 50 intersect to form a third cutting edge 64. The cutting edges 60, 62 and 64 preferably converge toward the common insertion point 52 from the solid body portion 40 and are preferably circumferentially spaced about the central axis 54 at an angle B of approximately 120 degrees. Since the cutting edges extend along the intersection of the wedge faces, they also extend or slope from the solid body portion 40 to the common insertion point or central axis 54 at an angle A in the range of approximately 5-30 degrees, and more preferably at an angle A of approximately 15 degrees. In this manner, the length of each cutting edge 60,62 and 64 can be less than a cutting length of the prior art angle ground hollow needle to thereby reduce material costs.

The introducer needle 18 is preferably constructed from a solid rod or bar of material, such as stainless steel, by cutting the rod or bar to a predetermined length, then grinding or otherwise forming one end of the rod or bar to form the tip portion 42.

Referring again to FIG. 1, in use, and by way of example, the infusion set 10 is loaded onto the slide assembly 26 of the inserter assembly 12. The slide assembly 26 is then retracted to the cocked position and held in place by the locking mechanism 28. The inserter assembly 12 is then positioned against the skin of a user and the button 30 is depressed to release the slide assembly 26. The infusion set 10 moves together with the slide assembly under spring bias toward the skin until the introducer needle 18 and cannula 14 are positioned in the subcutaneous layer. The concentric location of the insertion point 52 together with the symmetrically spaced cutting edges 60, 62 and 64 facilitate insertion of the introducer needle 18 into the skin with a concentric coaxial force. This coaxial force has no bending component, as in the prior art angle ground hollow needles. The three cutting edges 60, 62 and 64 cooperate with the concentric insertion point52 and the wedge faces 46, 48 and 50 to minimize skin displacement during needle insertion while assuring a clean cut through the tissue. In addition, the solid construction of the introducer needle 18 gives added strength over prior art hollow body constructions.

Still another advantage of the above-described introducer needle 18 is less burr formation and easier burr removal during manufacturing than in the prior art angle grinding of hollow needles.

Still further, the introducer needle 18 facilitates assembly of the infusion set 10. When inserted through the cannula 14 during assembly, the introducer needle 18 glides through without touching or damaging the cannula 14 since the insertion point 52 is spaced away from the wall of the cannula.

Referring now to FIG. 5, a front elevational view of an introducer needle 18a in accordance with a further embodiment of the invention is illustrated. The introducer needle 18a has a tip portion 42a with a plurality of substantially planar wedge faces, such as first wedge face 70, second wedge face72, third wedge face 74, and fourth wedge face 76 that converge toward a common insertion point78 from the body portion 40. The insertion point 78 is preferably coincident with a central axis of the introducer needle 18A. Preferably, the wedge faces extend from the solid body portion 40 to the central axis 78 at an angle A in the range of approximately 5-30 degrees, and more preferably at an angle A of approximately 15 degrees.

As shown, the first and second wedge faces 70 and 72 intersect to form a first cutting edge 80, the second and third wedge faces72 and 74 intersect to form a second cutting edge82, the third and fourth wedge faces 74 and 76 intersect to form a third cutting edge 84, and the fourth and first wedge faces 76 and 70 intersect to form a fourth cutting edge 86. The cutting edges80-86 preferably converge toward the insertion point 78 from the solid body portion 40 and are preferably circumferentially spaced about the central axis 54 at an angle C of approximately 90 degrees. Since the cutting edges extend along the intersection of the wedge faces, they also extend or slope from the solid body portion40 to the central axis 78 at an angle A that is preferably in the range of approximately5-30 degrees, and more preferably at an angle A of approximately 15 degrees.

While the two embodiments of the invention shown in FIGS. 4 and 5 illustrate inserter needles with 3 and 4 edge faces, it should be understood that the invention is not so limited and that 5 or more faces can be used.

While the invention has been taught with specific reference to the above-described embodiments, those skilled in the art will recognize that changes can be made in form and detail without departing from the spirit and the scope of the invention. By way of example, it will be understood that the invention is not limited to the particular number of wedge faces and cutting edges illustrated, but may have more or less faces and cutting edges. In addition, the angles between the cutting edges and/or their slopes can be asymmetrical. Moreover, although the introducer needle has been taught for use with an inserter assembly, it will be understood that the introducer needle is not so limited, but may be used in other devices and/or methods for positioning a cannula or catheter in a membrane or tissue and/or for creating a passage or opening in a membrane or tissue. Thus, the described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes that come within the meaning and range of equivalency of the claims are to be embraced within their scope.

We claim:

1. An infusion set (10) comprising: a cannula housing (16);

a cannula (14) extending from the cannula housing (16); and an introducer needle (18) extending through at least a portion of the cannula (14), the introducer needle (18) comprising:

a solid body portion (40) having a central axis (54);

a solid tip portion (42) extending from the solid body portion (40), the solid tip portion (42) comprising:

a common insertion point (52) that is coincident with the central axis (54); a plurality of wedge surfaces (46, 48 and 50) extending from the solid body portion (40) and converging toward the common insertion point (52), each wedge surface forming an intersection with an adjacent wedge surface; and

a plurality of cutting edges (60, 62 and 64) formed at the intersections of the wedge surfaces, the cutting edges (60, 62 and 64) converging toward the common insertion point (52);

wherein insertion of the introducer needle (18) into the membrane causes even cutting and separation of the membrane around the introducer needle.

2. The infusion set as claimed in claim 1, wherein the plurality of wedge surfaces comprises first (46), second (48) and third (50) wedge surfaces, with the first (46) and second wedge surfaces (48) intersecting at a first intersection, the first (46) and third wedge surfaces (50) intersecting at a second intersection, and the second (48) and third wedge surfaces (50) intersecting at a third intersection.

3. The infusion set as claimed in claim 2, wherein a first angle is formed between the first (46) and second (48) wedge surfaces, a second angle is formed between the first (46) and third (50) wedge surfaces, and a third angle is formed between the third (50) and first (46) wedge surfaces.

4. The infusion set as claimed in claim 3, wherein the plurality of cutting edges comprises a first cutting edge (60) located at the first intersection, a second cutting edge (62) located at the second intersection, and a third cutting edge (64) located at the third intersection.

5. The infusion set as claimed in claim 4, wherein the first, second and third angles are each approximately 120 degrees.

6. The infusion set as claimed in claim 5, wherein the first (60), second (62) and third (64) cutting edges have a slope in the range of about 5 degrees to about 30 degrees with respect to the central axis.

7. The infusion set as claimed in claim 6, wherein the first (60), second (62) and third (64) cutting edges have a slope of about 15 degrees with respect to the central axis.
8. The infusion set as claimed in claim 4, wherein the first (60), second (62) and third (64) cutting edges have a slope in the range of about 5 degrees to about 30 degrees with respect to the central axis.

9. The infusion set as claimed in claim 1, wherein each wedge surface extends at an angle in the range of about 5 degrees to about 30 degrees with respect to the central axis.
10. The infusion set as claimed in claim 9, wherein each wedge surface extends at an angle of about 15 degrees with respect to the central axis.

11. The infusion set as claimed in claim 1 comprising a cannula housing (16), with the cannula (14) and introducer needle (18) extending from the cannula housing (16).

12. The infusion set as claimed in claim 11 comprising an adhesive pad (20) connected to the cannula housing (16) for securing the cannula housing (16) to the skin of a user.

13. The infusion set as claimed in claim 1, wherein each wedge surface is planar.

14. An infusion set substantially as herein described with reference to the accompanying drawings.