WO1998013092A1

WO1998013092A1 - Tissue penetration guide

Info

Publication number: WO1998013092A1
Application number: PCT/US1997/016813
Authority: WO
Inventors: Michael Jay Gast
Original assignee: American Home Products Corporation
Priority date: 1996-09-27
Filing date: 1997-09-23
Publication date: 1998-04-02
Also published as: AU4357397A

Abstract

The present invention provides a tissue penetration guide (8) which limits range of motion of a device (2) useful for insertions under and substantially parallel to the surface of a particular tissue (10) or overlapping series of tissues such that the insertion is made to the desired depth.

Description

TISSUE PENETRATION OTJTDE

This application concerns a tissue penetration guide designed to facilitate the proper insertion of an instrument or device into a desired position under or inside the tissue in question. More particularly, the present invention relates to a novel means for assuring that particularly-directed medical instruments, such as trocars, needles, tubes, probes, etc., can be placed into a desired position under or inside a particular tissue. The tissue penetration guide is most particularly appropriate for directing such medical devices into a desired position for subcutaneous insertion, placement, probing, injections, implantations, depositions, etc.

Background of the Invention

The prior art provides a number of mechanisms for implanting materials, particularly medically applicable materials, in an animal. U.S. Patent No. 4,451,253 (Harman) teaches an implant injector with a stable obturator held secured within the injector body and a retractable, hollow needle or trocar. In its initial position the needle is extended such that an implant rests inside the needle against the distal end of the stable obturator. After the needle is injected into the desired position, the retractable needle is withdrawn along the obturator to uncover and deposit the implant. U.S . Patents Nos. 4,820,267 (Harman), 4,846,793 (Leonard et al.) and 4,994,028 (Leonard et al.) disclose devices with hollow, needle-like cannulas for implantation of a plurality of solid, elongated medicinal pellets. These devices are designed such that a user slides a manually engageable knob along the body of the instrument to move a plunger through the needle and dispense the pellets. U.S. Patent No. 4,661,103 (Harman) teaches a similar device with a slotted barrel element to slidably mount an integral magazine for multiple implant pellets. U.S. Patent No. 4,871,094 (Gall et al.) provides an injector which utilizes a syringe-like, distally-protruding coaxial plunger and a side- loading opening for placing implants in the injector. The Gall et al. devices also include a staggered channel passing through the external surface of the device's body, with each section of the channel corresponding roughly in length to that of the implants. A laterally protruding knob on the plunger slides between points within the staggered channel to facilitate implantation of one pellet at a time. U.S. Patent No. 4,900,304 (Fujioka et al.) teaches another standard plunger, side-loading injector. The Fujioka et al. device differs in its side-loading activity from that seen in the Gall et al. device, above, in that the loading port is located in the side of the device's needle or trocar member, which is loaded with implants prior to being inserted into the body of the injector. U.S. Patent No. 4,402,308 (Scott) describes an implant injector having a hollow, slotted needle or trocar rotatably mounted inside a sheath, the sheath being retractable to expose any portion of the slotted needle. U.S. Patent No. 4,941,874 (Sandow et al.) provides for a transparent injector with a protective covering to protect the plunger rod and prevent it from falling out. U.S. Patent No. 4,753,636 (Free) teaches a syringe- style implant injector in which a tab-like clip is releasably secured to positions on the obturator to regulate its forward progress and limit each implantation to a single implant pellet. U.S. Patent No. 4,147,164 (Behney) directs a method of placing shape correcting implants into canine ears. Finally, U.S. Patent No. 5,385,554 (Brimhall) teaches a wing-shaped pair of extensions for a catheter inducer which facilitates the gripping of the needle.

In addition, the prior art has addressed some means and methods for inserting devices into tissues at reasonably prescribed angles. U.S. Patent No. 2,577,481 (Piechaczek) set forth an apparatus comprising, generally, a flattened base to be placed against a patient's skin and adjustable means for altering the angle at which a hypodermic needle passes through the plane of the base. Similarly, U.S. Patents Nos. 5,024,665 and 4,966,589 (both to Kaufman) describes a composite catheter assembly which secures the body and needle of an inserting device such that its angle of penetration into the body is substantially maintained during operation. U.S. Patent No. 5,192,271 (Kalb et al.) discloses a device for delivering an injection to a penis, the device comprising a ring designed to encircle the penis, the ring having one or more tubular extensions protruding from the ring such that a hypodermic needle passing through the tube and ring is guided to the central erectile tissue. U.S. Patent No. 5,395,317 (Kambin) provides a method of treating a herniated disc, the method including a jig which utilizes substantially parallel channels in a jig and an original guide passing through one channel to align subsequent linear devices and direct them toward the desired location in relation to the disc. U.S. Patent No. 4,403,987 (Gottinger) discloses an injection aid comprising, in general terms, a hypodermic syringe, an angled ramp means, and a base, the base being designed to secure the syringe and slide down the ramp means at the prescribed angle to make a desired injection into a limb. U.S. Patents Nos. 3,324,854 (Reese) and 2,660,169 (Malm) disclose syringe attachments which protrude from the needle end of a syringe and allow the user to guide the syringe's needle into a specified, upraised portion of skin. Finally, U.S. Patent No. 5,300,079 (Niezink et al.) teaches a spring operated injector designed to implant objects such as transponders used for identifying hogs. The injector utilizes a positioning means comprising a pin which is set against a body as a guide for an insertion needle to be passed parallel to the pin and into and out of the body.

While each of these devices provide means for inserting a medical device, such as a needle, cannula or trocar, into tissues, none limits the angle of insertion such that the device or materials they are designed to implant, inject or deposit can be placed only at the desired depth underneath and substantially parallel to the surface of the tissue.

Brief Description of the Invention

In certain medical, veterinary or dental procedures it is necessary to direct an insertable, substantially linear device, such as a cannula, hypodermic needle, trocar, catheter, probe, tube, etc., under and substantially parallel to the surface of a particular tissue or overlapping series of tissues. Examples include subcutaneous hypodermic injections and the subcutaneous implantation of solid, time-release medicaments, including conα-aceptive implants. Also included are the insertion of reconstructive or cosmetic implants, such as the veterinary implants described in U.S. Patent No. 4,147,164 (Behney), mentioned above. During these types of procedures a portion of the device is inserted at a particular angle to reach a prescribed location relative to the surface of the surrounding tissue.

In general, the present invention comprises a penetration guide to be used in conjunction with a device designed to be inserted under a layer of tissue or tissues, substantially parallel to the surface of that tissue or tissues, the device having an extended, substantially linear portion designed to be inserted into or under the tissue.

The tissue penetration guide of this invention comprises a substantially linear, preferably linear, extension of material maintained substantially parallel to, preferably parallel to, and separated from the extended portion of the device designed to make the insertion in question. The guide is designed to remain on or near the surface of tissue to be entered and guide the insertable portion of the device or instrument to its desired inserted position. More particularly, the present invention provides a guiding means separated from and substantially parallel to the insertable portion of the device or instrument such that the device may be passed into the tissue only to a certain depth and, if the instrument is not inserted substantially parallel to the surface of the tissue, it must be oriented substantially parallel to the surface of the tissue before further forward progress can be achieved. As this occurs, the amount of tissue corresponding to the desired depth passes between the tissue penetration guide and the insertable portion of the instrument in question. It will be understood that the distance between the guide and insertable portion of the instrument will preferably be only that which allows the tissue to pass between and in close proximity to both the guide and the instrument. In cases where the depth of insertion is critical, this distance may be defined such that the tissue inserted touches both the guide and the instrument as it passes between them. While some flexibility may be preferable for certain uses where the depth of insertion of the insertable is not as critical, it is most preferred that the tissue penetration guide be relatively rigid and inflexible to restrict the motion and insertion of the device's insertable portion to the intended position.

The penetration guide may have any physical shape which allows the activity just described, preferably having dimensions which will not catch, bind or irritate the tissue in question or hinder the intended insertion. These shapes may include, but are not limited to, rods or columnar projections. The projections may be designed such that, in lateral cross-section, they are circular, elliptical, square, rectangular, or any other design which does not lead to unwanted effects on the tissue or inhibit the desired insertion.

In another preferred embodiment, the penetration guide does not extend along the full length of the insertable portion of the instrument. Rather, the most extended portion of the instrument projects beyond the guide such that this instrument may create an opening in the tissue, or be passed through a pre-existing opening or incision, before the guide contacts the external surface of the tissue and directs further insertion of the instrument substantially parallel thereto. In this embodiment, it is preferable that the distal or most extended portion of the device to be inserted projects beyond the distal or most extended portion of the tissue penetration guide by a distance slighdy greater than the thickness of the tissue in question. This difference in lengths allows the instrument to be inserted under the tissue and may act as a lever to lift the tissue from the underside as the instrument is angled for the desired insertion. With the tissue so elevated, the instrument may then be inserted with a diminished chance of grasping and tearing or ripping the tissue.

For the purposes of this disclosure, the term distal is used to refer to those portions of the device normally held away from the operator during use, such as the sharpened end of a trocar or hypodermic needle, and proximal refers to those portions of the device normally held toward the operator during use.

In a most preferred embodiment, the present invention comprises a skin penetration guide to be used in conjunction with a device designed to make subcutaneous insertions in a mammal, preferably in a human. In devices of this embodiment, the tissue penetration guide comprises a substantially linear, more preferably linear, extension of material maintained parallel to and separated from the extended portion of the device designed to make the subcutaneous insertion. The guide is designed to remain on or near the surface of skin to guide the inserted portion of the device or instrument to its desired position. Devices of this embodiment include those syringes and injectors particularly useful for making subcutaneous injections or implantations of solid medicaments, particularly solid, time-release medicaments, including contraceptives. It will be understood that the devices in question will have a skin penetration guide which is separated from their insertable portions by a distance designed to accommodate the passage of skin between them. It is understood that the space of this separation will vary from species to species depending upon the thickness of animal's skin. A space of between 0.05 and 0.10 inches (1.25 to 2.5 mm), preferably about 0.075 inches and about 0.095 inches (1.88 to 2.41 mm) between the penetration guide and the insertable portion is preferred for devices used to make subcutaneous injections or implantations in humans, most preferably a space of between about 0.080 inches and about 0.090 inches (2.03 to 2.29 mm). The insertable portions may include, but are not limited to, trocars and the syringe cannulas used for injections, including both sharpened cannulas, such as hypodermic needles, and blunt cannulas. Brief Description of the Drawings

Fig. 1 provides a cross-sectional side view of an implant injector utilizing a tissue penetration guide of the present invention.

Fig. 2 provides a cross-sectional side view of the implant injector of Figure 1 with its trocar inserted through the skin of an animal.

Fig. 3 presents an additional cross-sectional side view of the implant injector of Fig. 2 after it has been further inserted subcutaneously.

Detailed Description of the Invention

An embodiment of the present invention can be seen in the cross-sectional, side view of a subcutaneous implantation device utilizing a tissue penetration guide in Fig 1. The implantation device comprises a tubular needle or attached trocar (2) secured to the device's body (1) such that a tubular channel (3) passes co-axially through them, the channel (3) having internal dimensions sufficient to accommodate the passage of a solid columnar or cylindrical subcutaneous implant (4). For the purposes of describing Figs. 1-3 herein, the term "trocar" is understood to refer to a distally sharpened cannula secured by its proximal end to the injector body (1). The trocar (2) in these figures is intended to remain secured to the device's body and is not left in its inserted position in a tissue once the injector body has been removed from its injection or insertion position.

Passage of the implant (4) through the device is facilitated by a standard obturator or plunger rod (5-7). A tissue penetration guide (8) of the present invention extends from the implantation device's body (1) substantially parallel to and separated from the trocar (2) by a pre-determined space (9). In the embodiment illustrated in Figure 1, the guide (8) does not extend along the full length of the needle or trocar (2).

In operation, the subcutaneous implantation device's trocar is directed toward the patient's skin with trocar (2) between the skin and the tissue penetration guide. As illustrated in Figs. 2 and 3, the trocar (2) is then inserted through the skin (10) at the desired location and angled such that its further progress is underneath and substantially parallel to the surface of the skin (10). The penetration guide (8) is oriented relative to the distal end of the trocar such that it contacts the external surface of the skin (10) and inhibits further forward progress of the trocar (2) (Figure 2) unless the device is brought to a more appropriate angle relative to the skin such that the trocar (2) passes under and substantially parallel to the skin (10), with the layer of skin (10) passing into the space (9) separating the guide (8) and the trocar (2) (Figure 3). Passage of the trocar under the skin (10) creates an opening into which the solid implant (4) can be deposited. Deposition is accomplished by grasping the obturator by its handle (7) or rod (5) portions and retaining it in a stable position while withdrawing the injector's trocar (2) from its inserted position. The forward or distal end (6) of the obturator contacts the implant (4) and maintains it in position under the skin as the injector is withdrawn.

While Figs. 1-3 illustrate an injector design with a single solid implant (4) contained therein, it will be understood that the penetration guide of the present invention may be used with implantation devices of various body styles designed to accommodate a plurality of implants.

In other embodiments of this invention, the penetration guide extends along the entire length of, or extends beyond, the insertable portion of medical instrument. Such embodiments are particularly useful for insertions in which the insertable portion of the device is not required to make the initial puncture through the tissue. They may also be preferred for those activities where the depth the insertable portion is allowed to pass below the surface tissue is to be particularly limited.

The penetration guides of the present invention may be maintained at the desired distance from the insertable portion of the device by any means which does not hinder the activities of the desired insertion. Preferably, the guide will be coupled directly to the device itself and may be releasable. The coupling may occur directly to the insertable portion of the instrument, with the means of coupling being located sufficiently from the most extended or distal portion of the instrument to be inserted to allow the desired insertion. In many instances it may be preferable to couple the penetration guide to the insertable portion such that the most proximal or forward portion of the coupling means contacts the tissue passing over the insertable portion and prevents further insertion. In this manner the guide not only prescribes the angle and depth relative to the tissue through which the device can be inserted, it also determines the depth under the tissue to which the insertion can be accomplished.

The penetration guide may be narrower or wider than the insertable portion of the device. The penetration guide may also be longer or shorter or the same length as the device's insertable portion, i.e. in their working orientation the guide may extend beyond the insertable portion, or vice versa. In other embodiments, the most proximal or terminal portions of both may extend substantially the same distance from the medical device. The penetration guide may also be adjustable in length so as to alter the extension with respect to the insertable position.

For other uses the penetration guide will more preferably be secured to a portion of the device other than the insertable portion, such as on the body or housing of the device. In the case of an injector designed for solid, subcutaneous implants, such as that illustrated in Figs. 1-3, it is desirable that the guide be an extension of the main body of the injector, preferably as an integral, solid, molded portion of the body, itself. In the case of syringes, it is preferable that the penetration guide be coupled, releasably or otherwise, to the body of the syringe or to the hub bearing the syringe's cannula. The guide may be coupled to the device at any location and in any manner which allows the desired actions and uses of the device. As with the injector body just described, the penetration guide can be molded as an extension of the syringe's cannula hub.

In other embodiments, it may be preferable to utilize means for adjusting the distance by which the penetration guide is separated from the insertable portion of the instrument or device. Such means may include any design which allows the penetration guide to be separated from the insertable portion by set distances or by any distance over a specified range.

The penetration guide may comprise a plurality of substantially parallel extensions from the housing or body, each substantially parallel to and, preferably, equidistant from the insertable portion of medical instrument. Most preferably, the penetration guide is a single extension. The penetration guide may also be designed to allow only a single distance between itself and the insertable portion of medical instrument or the penetration guide may be adjustable to allow the operator to set the distance between the two according to the thickness of tissue or tissues in question. The distance or gap between the penetration guide and the insertable portion of medical instrument may be any separating distance which allows the tissue to pass between the two and limits the insertion of the insertable portion of medical instrument to the desired depth under the tissue or tissues. When the tissue is human skin and the insertion is designed to be subcutaneous deposit, as in the case of depositing solid contraceptive implants, it is preferred that the penetration guide is separated from the insertable portion of medical instrument by a distance of between about 0.075 inches and about 0.095 inches (1.88 to 2.41 mm), most preferably by a distance of between about 0.080 inches and about 0.090 inches (2.03 to 2.29 mm).

It will be understood that the penetration guides of this invention may be made from any material sufficiently rigid to accomplish the intended functions. In many applications, the material will preferably be a moldable polymer, such as nylon 66 or a polyacrylic. A clear material, such as a polyacrylic, may be advantageous for methods in which the ability to view the tissue through the guide is an advantage. If the materials are clear, such as with glass or a polyacrylic material, the top and bottom surfaces of the penetration guide may be rounded convexly or concavely to alter the angle and/or magnification of light passing through the guide. For some procedures, it may also be desirable to have lines, markings, raised or indented poπions or other visible markers on or in the surface of the penetration guide to serve as indicators to the depth of penetration of the device.

Claims

What is Claimed:

1. A penetration guide for use in conjunction with a device having a substantially linear portion designed for insertion into or under a tissue, the penetration guide comprising a substantially linear body maintained parallel to and separated from the substantially linear portion at a distance sufficient to allow the tissue to pass between the penetration guide and the substantially linear portion and having a length sufficient to restrict the insertion of the substantially linear portion to an angle which directs the substantially linear portion to a position under and substantially parallel to the surface of the tissue.

2. The penetration guide of Claim 1 and further including a device wherein the device is a subcutaneous insertion device, the substantially linear portion designed for insertion is a trocar or hypodermic needle, and in use the tissue is mammalian skin.

3. The penetration guide of Claim 2 wherein the penetration guide is separated in use from the trocar or hypodermic needle by a distance of between about 1.25 mm and about 2.5 mm.

4. The penetration guide of Claim 2 wherein the penetration guide is separated in use from the trocar or hypodermic needle by a distance of between about 1.88 mm and about 2.41 mm.

5. The penetration guide of Claim 2 wherein the penetration guide is separated in use from the trocar or hypodermic needle by a distance of between about

2.03 mm and about 2.29 mm.

6. The penetration guide of Claim 1 wherein the device is a hypodermic syringe, the substantially linear portion designed for insertion is a syringe cannula, and the tissue in use is skin.

7. The penetration guide of Claim 1 further being adjustable in length so as to alter the extension of the penetration guide with respect to the length of the insertable position.

8. The penetration guide of Claim 1 further having means for adjusting the distance separating the penetration guide from the substantially linear portion.

9. The penetration guide of Claim 1 wherein the penetration guide is releasable from the device.

10. A penetration guide for use in conjunction with a device having a cannula designed for subcutaneous insertion under skin, the penetration guide comprising a substantially linear body maintained in use parallel to and separated from the cannula at a distance sufficient to allow the skin above the insertion to pass between and in close proximity to the penetration guide and the cannula, the penetration guide further having a length sufficient to restrict the insertion of the cannula in use to an angle which directs the cannula to a desired subcutaneous position.

11. The penetration guide of Claim 10 wherein the device is a subcutaneous solid implant injector.

12. The penetration guide of Claim 10 wherein the penetration guide is separated in use from the trocar or hypodermic needle by a distance of between about 1.25 mm and about 2.5 mm.

13. The penetration guide of Claim 10 wherein the penetration guide is separated from the cannula by a distance of between about 1.88 mm and about 2.41 mm.

14. The penetration guide of Claim 10 wherein the penetration guide is separated in use from the cannula by a distance of between about 2.03 mm and about 2.29 mm.

15. The penetration guide of Claim 10 and further including a device wherein the device is a hypodermic syringe.