Insertion device for inserting an injection needle

An insertion device for inserting an injection needle into a tissue including a needle holder carrying the injection needle and a protection device for covering the injection needle after the removal thereof from the tissue wherein the needle holder is mounted to move along the needle axis in relation to the protection device and for insertion of the injection needle the needle holder and protection device are moved more closely together and wherein at least one catch is provided on at least one of the needle holder and protection device, which firmly engages the needle holder with the protection device in an extended relative position. The invention encompasses a catheter head having a base body, a flexible cannula extending from the base body and the insertion device with the protection device.

BACKGROUND

The invention relates to devices for inserting a needle or the like into tissue, and to methods of making and using such devices. More particularly, it relates to an insertion device for inserting an injection needle into a tissue, more particularly wherein the insertion device is part of a catheter head, and, more particularly, wherein the catheter head is part of an infusion set.

Many different types of insertion devices for inserting an injection needle into a tissue are known in the prior art. In addition to having a needle holder from which the injection needle protrudes, more recent insertion devices also comprise a protection device for protecting and/or covering the injection needle after withdrawal from the tissue. The protection device serves to protect the person using the insertion device from needle-stick injuries, as the injection needle is freely accessible after withdrawal from the tissue. Such insertion devices are used in various medical or therapeutic devices and procedures in which an active fluid substance or another liquid has to be introduced into a body tissue.

Insertion devices have been used for catheter heads for, for example, infusion sets. The catheter head serves as port for introducing a liquid active substance, e.g., insulin, growth hormones. etc., into the body tissue. For this purpose, the catheter head is applied for a considerable length of time on the surface of the body tissue. A flexible cannula protrudes from an underside of the catheter head into the body tissue. Because of its flexibility, the cannula can follow the movements and changes of the body tissue and thus causes as little discomfort as possible for the person using the catheter head. Above the tissue surface, a catheter leads from the catheter head to a receptacle containing the liquid active substance. The catheter is in fluidic communication with the cannula. For introducing the flexible cannula into the body tissue, a rigid injection needle can be used which, for example, is guided through the cannula such that the latter bears firmly on the injection needle, and whose insertion tip protrudes beyond the cannula. After the cannula has been introduced into the tissue, the rigid injection needle is pulled from the cannula, said cannula remaining in the tissue. The injection needle accordingly forms an insertion aid for the flexible cannula.

An insertion device with an injection needle as insertion aid for a catheter head as described above is described in WO 00/03757. The insertion device has a housing from which an injection needle protrudes in such a way that it reaches through a base body of the catheter head and extends through the flexible cannula of the catheter head. Arranged on one side of the housing of the insertion device, there is a protection device in the form of a sleeve cap which is pivotable relative to the housing and which is open at one end in the direction of the needle. In a first state for insertion of the injection needle, the sleeve cap protrudes from the housing perpendicularly with respect to the needle axis. After insertion of the injection needle, or flexible cannula, the insertion device is detached from the base body of the catheter head, the injection needle being withdrawn from the tissue or the flexible cannula. After the withdrawal of the insertion device, the sleeve cap can then be pivoted relative to the housing and over the injection needle. In doing this, the injection needle is bent sideways in the pivoting direction of the sleeve cap and is partially surrounded by the latter. On that side of the housing opposite from the sleeve cap, catch devices are provided in which the sleeve cap engages after pivoting, in such a way that it is not pivoted back by the restoring force of the bent needle. However, after withdrawal from the tissue or from the base body of the catheter head, the injection needle is initially exposed, as a result of which there is a risk of injury to the user. Moreover, the sleeve cap has to be guided manually over the injection needle, as a result of which there is an additional risk of injury because various maneuvers have to be performed in the vicinity of the injection needle.

SUMMARY

It is an object of the present invention to make available an insertion device, for inserting an injection needle into a tissue, whereby risk of injury after removal of the injection needle from a tissue is reduced or eliminated, whereby a protection device for protecting or covering the injection needle can be easily arranged around the injection needle, whereby the injection needle is at all times protected during withdrawal, and for which no additional maneuvers are required in order to protect the injection needle after removal of the insertion device.

It is a further object of the invention to make available a catheter head for medical or pharmaceutical applications, whereby risk of injury from using an injection needle as insertion aid for a flexible cannula is reduced or eliminated, an insertion aid can be easily detached after introduction of the flexible cannula, and the catheter head can be easily placed on a tissue.

Accordingly, in one embodiment, the present invention comprises an insertion device for inserting an needle into tissue, comprising a needle holder carrying the needle, a protector for covering the needle after removal from the tissue, wherein the needle holder is axially movable relative to the protector and for insertion of the needle is generally inside the protector, and a catch for holding the needle holder and protector together in a position in which the needle holder is generally outside the protector.

In one embodiment, the present invention comprises an insertion device for inserting an injection needle into a tissue comprising a needle holder carrying the injection needle and a protection device for covering the injection needle after the removal thereof from the tissue, wherein the needle holder is mounted to move axially in relation to the protection device and for insertion of the injection needle the needle holder and protection device are moved more closely together, and wherein at least one catch is provided on at least one of the needle holder and protection device, the at least one catch engaging the needle holder with the protection device in an extended relative position. The invention encompasses a catheter head having a base body, a flexible cannula extending from the base body and the insertion device with the protection device.

In one embodiment, the present invention comprises an insertion device for inserting an injection needle into a tissue, comprising a needle holder from which the injection needle protrudes and a protection device for protecting the injection needle after removal from the tissue, wherein the needle holder is mounted so as to slide along the needle axis in relation to the protection device and, for insertion of the injection needle, the needle holder is in a position in which it is pushed together with the protection device, at least one catch device provided on at least one of the needle holder and the protection device, which catch device firmly locks the needle holder and the protection device together at least in a position in which they are drawn apart from one another.

In one embodiment, according to the present invention an insertion device for inserting an injection needle into a tissue comprises a needle holder from which the injection needle protrudes, and a protection device for protecting the injection needle on removal from the tissue. The needle holder is mounted so as to slide along the needle axis in relation to the protection device. For this purpose, the needle holder and the protection device can be designed like sleeves so that they can be pushed one into the other. The needle holder can be pushed over the outside of the protection device or can be pushed into the inside of the protection device. For insertion of the injection needle, the needle holder is in a position in which it is pushed together with the protection device. The injection needle protrudes from the protection device such that it can be inserted into the tissue. In this position, access to the injection needle can be prevented by a protective cap, which is removed shortly before the insertion. When needle holder and protection device are being drawn apart, the needle holder is moved relative to the protection device along the needle axis into a drawn-out position in which the tip of the injection needle is surrounded by the protection device in some preferred embodiments, the protection device remains fixed relative to the tissue. The injection needle is pulled out of the tissue directly into the inside of the protection device and is at no time exposed. In order to lock the needle holder and the protection device securely to one another at least in the drawn-out position, at least one catch device is provided on the needle holder and/or the protection device. In this way, after it has been locked, the needle holder cannot fall back into a pushed-together position in which the injection needle could protrude from the protection device. In this regard, it is advantageous if, when needle holder and protection device are drawn apart, the at least one catch device not only blocks them against renewed sliding together in the completely drawn-out position, but also blocks them against sliding together even after just partial drawing apart, when a part of the injection needle still lies inside the tissue.

According to a further aspect of the present invention, an insertion device according to the invention forms a part of a catheter head for medical and pharmaceutical applications, as is disclosed, for example, in the application DE 102 55 817.5 belonging to the owner of the present application. Such a catheter head has a base body with a flexible cannula protruding from it. The insertion device is used for introducing the flexible cannula into a tissue. The insertion device is in this case designed in the manner described above.

In a preferred embodiment of the present invention, the protection device of the insertion device is connected to the base body of the catheter head, the base body resting on a surface of the tissue. It is conceivable in principle to connect the protection device to the base body in a detachable manner. However, this is not necessary in the described embodiment. In the position in which needle holder and protection device are pushed together, the injection needle protrudes through the base body. In some embodiments, the injection needle preferably protrudes from the base body perpendicularly with respect to a surface of the base body via which it rests on the tissue surface. For introducing the flexible cannula of the catheter head, the injection needle extends through the flexible cannula and its tip protrudes beyond the latter. After insertion of the injection needle or flexible cannula into the tissue, the needle holder is moved relative to the protection device along the needle axis and, in this process, the injection needle is pulled out of the tissue or cannula. In the position in which the needle holder has been drawn out, the injection needle is pulled back completely into the protection device.

If it is desired that the insertion device be provided detachably on the catheter head, the insertion device may be arranged on the catheter head in such a way that the insertion device, in the drawn-out position of the needle holder, can be pulled out from the base body in a direction perpendicular to the needle axis, i.e. parallel to a surface of the tissue. In this way it is possible to avoid a situation where, by removing the insertion device from the catheter head, the catheter head is lifted from the tissue surface and the flexible cannula is pulled at least partially from the tissue. However, it is also possible in principle to remove the insertion device from the base body in a direction parallel to the needle axis.

Using an insertion device and a catheter head according to the present invention, it is possible to remove an injection needle from a tissue without risk of injury to the user. During removal from the tissue, and in the withdrawn position, the injection needle is covered and inaccessible. By means of the catch device between needle holder and protection device, it is not possible to expose the injection needle after it has been drawn back into the withdrawn position of the needle holder relative to the protection device. The needle protection is already arranged over or around the injection needle in a simple manner upon withdrawal of the injection needle from the tissue, and no additional operating step is needed in order to arrange the protection device around the injection needle. The insertion device can be detached from the catheter head in a simple manner, without any risk of the catheter head being lifted from the tissue surface. This is because the movement for detaching the insertion device from the catheter head is perpendicular to the movement for withdrawing the injection needle or for withdrawing the needle holder from the protection device.

In a preferred embodiment of the present invention, at least one guide arrangement is provided between protection device and needle holder for the purpose of guiding the needle holder during its movement relative to the protection device along the needle axis. The guide arrangement can be formed, for example, by one or more guide grooves which are provided on the protection device and into which a projection arranged on the needle holder engages. Of course, the guide grooves can also be provided on the needle holder and, accordingly, the projections on the protection device. Other suitable complementary structures or arrangements may be used as well.

For locking the needle holder to the protection device in the drawn-out position of the needle holder, the catch device comprises at least one first limit stop for blocking the needle holder in the direction of drawing apart, and at least one second limit stop for blocking the needle holder in the direction of pushing together. For example, a first limit stop can be formed by a projection on the needle holder striking against an abutment on the protection device when the needle holder is in the drawn-out position. Of course, the projection can also be provided on the protection device, and the abutment on the needle holder. Such an abutment can be formed, for example, by a step or a projection or an outer surface of the needle holder or of the protection device. The second limit stop for blocking against sliding together is preferably arranged on at least one element acting in the manner of a leaf spring. The second limit stop can be provided by a projection on the leaf spring element which strikes against an abutment in the drawn-out position of the needle holder. For the catch device, one or more leaf spring elements can be provided on the needle holder or on the protection device or also on both of these. A leaf spring element is formed, for example, by a slat-like extension on the needle holder or on the protection device, which slat-like extension protrudes, substantially parallel to the needle axis, from the needle holder in the direction of the protection device or from the protection device in the direction of the needle holder. The extension is arranged fixedly on the needle holder or on the protection device. It is preferably made in one piece with the needle holder or the protection device, for example by injection molding. However, the extension is able to bend relative to the needle holder or the protection device and can thus be pretensioned. In principle, however, the leaf spring element can also be formed by being fixed with opposite ends on the needle holder or protection device.

For an insertion device according to the present invention, it is of course also possible to use catch devices other than leaf spring elements in the form of slat-like extensions with the corresponding limit stops, provided that secure locking is possible in the drawn-out position of needle holder and protection device. For example, catch elements could be used which are pretensioned by helical springs or elastic rubber elements which are compressed when the needle holder and the protection device are drawn apart and which expand in the withdrawn position. As far as the configuration of the catch device is concerned, it must simply be ensured that the catch mechanism is based on the principle of the slidability of the needle holder along the longitudinal axis of the injection needle relative to the protection device, in order to permit locking as a consequence of the needle being withdrawn from the tissue.

In some embodiments, the needle holder and the protection device preferably have a right-parallelepiped shape, with a broad or long side and with a short or narrow side. A first limit stop for blocking against the drawing apart of needle holder and protection device is formed by two slat-like extensions which are each arranged on opposite short sides. The second limit stop for blocking against the sliding together of needle holder and protection device is formed by four slat-like extensions, with two of said extensions on each broad side. A sliding together of needle holder and protection device is thus prevented by four symmetrically arranged points of engagement between needle holder and protection device. In principle, it is possible to provide all the slat-like extensions for the first limit stop and for the second limit stop either on the needle holder or on the protection device. It is also possible, however, to provide the extensions for a first limit stop on the needle holder, and to provide the extensions for a second limit stop on the protection device, or vice versa.

In one embodiment of the catch device, it is possible for the slat-like extensions to be in a pretensioned state when the needle holder and the protection device are in the pushed-together position, and for said extensions to be released into an untensioned blocking state when the needle holder and protection device are in the drawn-apart position. In another embodiment, it is possible for the slat-like extensions to be in an untensioned state in the pushed-in position, and to be pretensioned, for example by a ramp, when needle holder and protection device are drawn apart. It is advantageous if the projections on the slat-like extensions engage in consecutive abutments, for example inside the guide arrangement, and, in this way, a renewed sliding together of needle holder and protection device is prevented even during the drawing-apart movement. Accordingly, the locking of the needle holder to the protection device by means of the catch device can take place, according to the invention, by untensioning of the slat-like extensions or by pretensioning of the slat-like extensions. To block the needle holder relative to the protection device in the drawn-out position, the projections on the slat-like extensions cooperate with the respectively opposite abutments.

Care should be taken to ensure that, during insertion of the injection needle, the needle holder is not moved relative to the protection device simply by the resistance exerted by the tissue in relation to the injection needle. If the slat-like extensions are pretensioned while the needle holder is being drawn out of the protection device, the resistance force of the extensions, which acts counter to the pretensioning, may be sufficient to prevent the needle holder being moved relative to the protection device as a result of the insertion of the injection needle. However, in some embodiments, a locking device can additionally be provided for locking and unlocking the needle holder and protection device in the pushed-together position on the insertion device. In the locked state, the needle holder cannot be moved relative to the protection device and therefore, during insertion of the injection needle into the tissue, also cannot accidentally be pushed out from the protection device. After insertion of the injection needle, the locking device can be unlocked so that the needle holder can be moved relative to the protection device. The locking device can advantageously be connected to two points of engagement for the needle holder, such that the locking device can be unlocked at the same time as the needle holder is being drawn out from the protection device. This can be done, for example, by pressing in grip surfaces into the needle holder. Moreover, the locking device can also be coupled to the catch device. For this purpose, for example, corresponding projections can be provided on the slat-like extensions, said projections striking against an abutment in the pushed-together position and being released from these abutments by the pressure on the grip surfaces of the needle holder.

DETAILED DESCRIPTION OF THE DRAWINGS

With regard to fastening, mounting, attaching or connecting the components of embodiments of the present invention, unless specifically described as otherwise, conventional fasteners such as screws, rivets, toggles, pins and the like may be used. Other fastening or attachment means appropriate for connecting components include friction fitting, adhesives, welding and soldering, the latter particularly with regard to electrical or processing components or systems. Any suitable electronic, electrical, communication, control or controller, computer or processing components may be used, including any suitable electrical components and circuitry, wires, wireless components, sensors, chips, boards, micro-processing or control system components, software, firmware, hardware, etc. References positional orientation (e.g., upward and downward) are used herein for ease of description.

FIG. 1shows a needle holder1of an insertion device according to one embodiment of the present invention, in which the needle holder1is mounted slidably inside a protection or covering device (not shown inFIG. 1). An injection needle5projects downward from the needle holder1in the direction of a tissue. The needle holder1has substantially the shape of a right parallelepiped with two broad sides, from which slat-like extensions2extend parallel to the injection needle5, and two short sides, from which in each case one slat-like extension4extends parallel to the needle5. The extensions2and4form one complementary part of a catch device of the insertion device according to the invention. In its inside, the needle holder1has a cylinder-like opening6in which further devices, for example a needle introducer device, can be accommodated. However, the needle holder1can also be closed on the top face. Arranged on each of the broad sides of the right-parallelepiped needle holder1, there is a grip surface7on which the needle holder1can be grasped and guided from two opposite sides.

The extensions2of the broad side of the needle holder1protrude from the needle holder1in such a way that they can bend to a certain extent, i.e., at least a portion of their length can move out beyond the plane formed by the broad side of the needle holder. In this embodiment, the extension4protrudes from the short side of the needle holder1in a rigid manner. However, it is also possible in principle for the extension4to be made so that it is flexible and/or can bend, i.e. it or a portion of it can be moved out beyond the plane formed by the short side of the needle holder1. As a result of the bending property of the extensions2and, if appropriate, also of the extensions4, these extensions can be pretensioned. They accordingly may be thought of and/or referred to as spring elements, leaf spring element, etc.

Arranged in the lower area of the slat-like extensions2, i.e. adjacent to the free end or in an area lying remote from the rest of the needle holder body, there are outwardly directed steps8which have a downwardly directed surface oriented perpendicular to the needle axis. Arranged on a lower area near the free end of the extensions4, there is a projection9which points outward in relation to the needle holder1and is provided with an upwardly directed surface oriented perpendicular to the needle axis.

InFIG. 2, the needle holder1fromFIG. 1is shown in a position in which it has been pushed into a protection device10. The protection device10is arranged on a base body14, as can be fitted for example onto a catheter head, the injection needle5protruding or extending downward through the base body14. The protection device10has a right-parallelepiped shape similar to the needle holder1and, in its inside, it has a cavity complementing or matching the needle holder1. On a broad side of the wall of the protection device10, there is a recess into which a grip surface7can be introduced with a form fit.

In a lower area of the broad side of the protection device10, the wall of said protection device10is provided with openings12in which the steps8of the slat-like extensions2of the needle holder1engage when the needle holder is in the pushed-in position. In this position, the slat-like extensions2are in an untensioned state or in a state with only slight pretensioning, in which state the extensions2are bent inward.

On the short side of the right-parallelepiped protection device10, on its inside surface, said protection device10has guide grooves13which each extend parallel to the needle axis. The slat-like extensions4of the needle holder1run at least partially inside the guide grooves13. The projections9of the extensions4at any rate project into the guide grooves13in the inside of the protection device10.

With the steps8protruding through the openings12, a locking mechanism is obtained by which a sliding of the needle holder1relative to the protection device10is made difficult. To be able to slide the needle holder1relative to the protection device10, it is necessary to overcome a high initial resistance created by bevels which are arranged on the steps8and which adjoin an edge of the openings12in the wall of the protection device10. The protection device10is connected securely to the base body14in the direction of the needle axis. To withdraw the needle holder1from the protection device10, the high initial resistance has to be overcome, the bevels on the steps8being guided along the edges of the openings12of the protection device10in such a way that the slat-like extensions2are bent inward and pretensioned until the outside of the steps8comes to lie on the inside of the wall of the protection device. To withdraw the needle holder1from the protection device10, it is then necessary to overcome the frictional force between the steps8and the inside of the protection device10. However, it is also possible to release the steps8from engagement in the openings12by pressing in the grip surfaces7so that the extensions2are bent slightly inward. When the needle holder1is released, the extensions2move back out again.

FIG. 3shows the insertion device according to one embodiment with a needle holder1drawn out from the protection device10. To slide the needle holder1from the pushed-in position (generally inside the protector) to the drawn-out position (generally outside the protector), the needle holder1is held via the grip surfaces7and pulled upward out of the protection device10counter to the direction of insertion of the injection needle5. The needle holder1is drawn out from the protection device10until the projections9on the extensions4abut the wall of the top face of the protection device10which delimits the guide grooves13. At the same time as the projections9abut the wall of the protection device10, the steps8on the extensions2emerge from the top face of the protection device10, i.e. above the top wall of the protection device. Because of their pretensioning, the extensions2move outward, and the downwardly directed surface of the steps8comes to lie opposite the upper wall of the protection device10. In this position, the needle holder is in a position in which it has been drawn out relative to the protection device10.

On the inner face of its broad side, the protection device10can have catches, for example in the form of steps or depressions, which come to lie opposite the steps8of the extensions2during the drawing out of the needle holder1. As the needle holder1is drawn out from the protection device10, the steps8on the extensions2can, by virtue of their pretensioning, engage in the depressions or catch above the steps in such a way that the needle holder1, also when being drawn out from the protection device10, is blocked by these catches against sliding back into the protection device10.

In the first embodiment shown, the slat-like extensions2and the steps8form, together with the outside face of the upper wall of the protection device10acting as abutment for the steps8, a first limit stop which blocks against the needle holder1being pushed into or pushed back into the protection device10. The extensions4and the projections9form, together with the inside face of the upper wall of the protection device10or the boundary of the guide grooves13acting as abutment for the projections9, a second limit stop which blocks the needle holder1against being drawn farther out from the protection device10. In this position, the needle holder1is locked securely to the protection device10, and the injection needle5is substantially completely surrounded circumferentially by the protection device10. In this position, the insertion device can be removed from the tissue surface and be disposed of without risk of injury from the injection needle.

FIG. 4shows a protection device10according to another embodiment of an insertion device according to the present invention, in which the protection device10comes to lie inside the needle holder1. The protection device10is a right parallelepiped, with a broad side and a short side. Provided on the broad side, there are two slat-like extensions15which are substantially parallel to the surface of the broad side and project upward, i.e. in a direction away from a tissue. Corresponding extensions15are formed on the opposite broad side. Arranged in an upper area on the extensions15, there is a step16which has an upwardly directed surface oriented perpendicular to the needle axis and which points outward. Formed on the short side, there is a slat-like extension17which is substantially parallel to the surface of the short side and like the extensions15projects upward from the protection device10. On the opposite short side of the protection device10there is a corresponding extension17. At the end of the extensions17, there is a projection18which points outward from the protection device10and has a downwardly directed surface oriented perpendicular to the needle axis. The extensions15and17protrude from the protection device10in a bendable manner, such that they can be pretensioned like leaf springs, in the same way as the extensions2and4of the first embodiment. The extensions15and17form, together with the steps16and the projections18, a part of the catch device according to the invention.

An opening19is formed in the central area of the protection device10. An injection needle5fitted on the needle holder1, and projecting perpendicularly downward from the needle holder1in the direction of a tissue, is guided through the opening19of the protection device10and also passes through the base body14so that it protrudes downward from the base body14and can be inserted into a tissue, through which a needle can be guided such that it can protrude from the underside of the base body14.

The protection device10of the insertion device inFIG. 4is placed on the top face of a base body14which forms part of a catheter head. The base body14is placed with its underside onto the surface of a tissue such that the protection device10is also fixed relative to the tissue.

InFIG. 5, a needle holder1has been pushed on over the protection device10. The needle holder1is situated in a position in which it has been pushed together with the protection device10. The needle holder1is substantially a right parallelepiped, such that it fits slidably onto the protection device10. To guide the needle holder1on the protection device10, guide grooves20are provided on the inside faces of the needle holder1in line with the extensions17, and also guide grooves21in line with the extensions15. The steps16of the extensions15or the projections18of the extensions17engage partially in the guide grooves20,21, respectively, or a part of the extensions. When the needle holder and the protection device are drawn apart, the steps16and the projections18are guided inside the guide grooves such that a simple sliding movement is permitted. The guide grooves21for the extensions15may have a ramp-like structure in order to pretension the extensions15when the needle holder1and the protection device10are drawn apart. At the lower end, the guide grooves20have a border parallel to the underside of the protection device10, so that, when the needle holder1and the protection device10are drawn apart, the projection18of the extension17abuts against this border. The guide grooves21for the extensions15, by contrast, open out at the bottom from the protection device, i.e. they open into the underside of the protection device10. The steps16of the extensions15could therefore emerge from the guide grooves21in the direction of the underside of the needle holder1.

At the lower edge of each broad side, the needle holder1has wings22which protrude perpendicularly from it and are angled downward in their end area. With the angled part, the wings22can engage in grooves or recesses23of the base body14and thus contribute to stabilizing the needle holder1. It is also possible to use the wings22, for example, to block a catch mechanism or locking mechanism of the base body14.

The insertion device according to the second embodiment is shown inFIG. 6in a position in which the needle holder1and the protection device10are drawn apart. The needle holder1can be pulled from the protection device10until the projections18of the extensions17abut the border of the guide grooves20. At the same time, the steps16of the extensions15emerge from the guide grooves21and, as a result of their pretensioning, engage the underside of the needle holder1, i.e. the bottom edge of the wall on the broad side of the needle holder1. In this position, the needle holder1and the protection device10are securely locked to one another, since further pulling of the needle holder1is blocked by the extensions17abutting against the borders of the guide grooves20, and renewed pushing-together of the needle holder1over the protection device10is blocked by the steps16of the extensions15abutting against the bottom edges of the needle holder1.

In the drawn out state, the injection needle5is drawn back completely into the protection device10and is surrounded by it in the circumferentially. Above all, the tip of the injection needle5remains inside the opening19of the protection device10, even though central areas of the injection needle are visible. The block in which the opening19is provided can, however, have an elongate shape in such a way that all areas of the injection needle are surrounded by it and the injection needle5is no longer visible.

As in the first embodiment of the present invention, it is also possible in the second embodiment to provide grooves or steps for the extensions15in the guide grooves21so that the steps16, when the needle holder1is pulled out from the protection device10, strike against an opposite groove or step and renewed sliding of the needle holder1onto the protection device10is blocked. In this way, after insertion of the injection needle and the start of withdrawal of the injection needle from the tissue by pulling the injection holder1from the protection device10, renewed insertion of the injection needle into the tissue is ruled out. If, for example, the injection needle5serves as an insertion device in a catheter head, this avoids damage to the flexible cannula by the needle tip.

The present invention has been explained using one illustrative embodiment with slat-like extensions2and4mounted on the needle holder1, and using a second illustrative embodiment with slat-like extensions15and16mounted on the protection device10. However, it is also possible in principle to provide such extensions both on the needle holder1and also on the protection device10, in which case guide grooves for the extensions can be provided in the respectively complementary part. Moreover, it is also possible to use one and the same extension to block against further withdrawal and to block against a sliding back in the retracted position of needle holder1and protection device10. The number of slat-like extensions can be varied, on condition that a secure locking of the needle holder1and the protection device10is ensured.

An insertion device according to the present invention can, as described, be used particularly advantageously as an insertion aid for a flexible cannula on a catheter head. However, it is possible in principle for an insertion device according to the invention also to be used in other medical and pharmaceutical applications. In particular, a fluid active substance can also be administered directly through the injection needle. The insertion device according to the present invention may also be used in other fields, including those concerning delivery of substances or the making of connections for the delivery of substances.

INDEX