Placement aid for placing a catheter for diabetics

Abstract

A placement aid for placing a catheter and a sensor wire into a body including a replacement device arranged in an interchangeable and replaceable manner having a main body, a placement needle, a catheter and a sensor wire. The placement needle is arranged within the catheter so that a tip of the placement needle protrudes from an end of the catheter along a puncturing direction and penetrates the skin when the catheter is inserted along the puncturing direction to generate a skin opening through which the catheter can be guided up to a subcutaneous final position. The sensor wire is arranged in the placement needle when the catheter is inserted along the puncturing direction and when the subcutaneous final position of the catheter is reached, the placement needle can be withdrawn from the catheter against the puncturing direction and the sensor wire remains in the catheter.

Claims

1. A placement aid for placing a catheter and a sensor wire into a body comprising: a placement device; a replacement device with a main body, a placement needle, a catheter and a sensor wire; wherein the replacement device is arranged in the placement device in an interchangeable and replaceable manner, wherein the placement needle is coupled to the main body, wherein the placement needle and the catheter are arranged with regard to each other in such a way that the placement needle is arranged within the catheter, and that a tip of the placement needle protrudes from a proximal end of the catheter along a puncturing direction so that upon placement of the catheter along the puncturing direction, the tip of the placement needle penetrates a skin in order to produce a skin opening through which the catheter can be guided up to a subcutaneous end position, and wherein the sensor wire is coupled to the placement needle in such a way that upon placement of the catheter along the puncturing direction, the sensor wire is arranged in the placement needle and that, upon reaching the subcutaneous end position of the catheter, the placement needle can be removed from the catheter against the puncturing direction and the sensor wire remains in the catheter; and a holding-down rod which is arranged in the placement needle in a displaceable manner, wherein the holding-down rod is designed to frictionally press the sensor wire against the placement needle, and wherein the holding-down rod is further arranged at the main body in a movable manner along the puncturing direction such that, upon placement of the catheter along the puncturing direction, the placement needle, the sensor wire and the holding-down rod can jointly be advanced up to the subcutaneous end position of the catheter and such that, upon reaching the subcutaneous end position of the catheter, the holding-down rod can be withdrawn from the catheter against the puncturing direction.

2. The placement aid according to claim 1, wherein the replacement device further comprises a piston and a needle holder, to which the placement needle is attached, wherein the piston is arranged in the main body in a displaceable manner, wherein the needle holder with the placement needle is arranged at the main body so as to be displaceable along the puncturing direction, wherein the needle holder is coupled to the catheter in such a way that, upon placement of the catheter, the needle holder advances the catheter along the puncturing direction, and wherein the piston is coupled to the needle holder in such a way that the needle holder can be advanced along the puncturing direction by means of the piston.

3. The placement aid according to claim 2, further comprising a first spring which is arranged between the main body and the needle holder in such a way that a first spring force of the first spring acts along the puncturing direction in order to advance the needle holder along the puncturing direction relative to the main body upon the placement of the catheter.

4. The placement aid according to claim 2, wherein the piston is designed to be introduced into and retracted from the main body in a telescopic manner.

5. The placement aid according to claim 2, wherein the piston is detachably coupled to the needle holder in such a way that, upon reaching the subcutaneous end position of the catheter, the needle holder can be decoupled from the piston and the needle holder can be moved relative to the piston against the puncturing direction.

6. The placement aid according to claim 2, further comprising a spring which is arranged between the placement device and the replacement device in such a way that a spring force of the spring acts along the puncturing direction in order to advance the needle holder along the puncturing direction upon placement of the catheter.

7. The placement aid according to claim 6, wherein the spring is set up in such a way that, when the needle holder is moved against the puncturing direction, the spring can be pre-tensioned.

8. The placement aid according to claim 6, wherein the placement device comprises a locking element and a trigger element, wherein the locking element locks the needle holder in an initial position, in which the spring is pre-tensioned, and wherein the trigger element is coupled to the locking element in such a way that, when operating the trigger element, the locking element releases the needle holder and the needle holder can be advanced along the puncturing direction by means of the spring force.

9. The placement aid according to claim 8, further comprising an additional spring which is arranged between the placement device and the replacement device in such a way that a spring force of the additional spring acts against the puncturing direction in order to displace the trigger element and the locking element back into their respective initial position.

10. The placement aid according to claim 6, wherein the piston is arranged in the placement device in a displaceable manner, and wherein the piston is coupled to the spring and to the needle holder in such a way that the piston and the needle holder can be advanced along the puncturing direction by means of the spring force.

11. The placement aid according to claim 2, further comprising a return spring which is arranged between the placement device and the needle holder in such a way that return force of the return spring acts against the puncturing direction in order to advance the needle holder against the puncturing direction after placement of the catheter.

12. The placement aid according to claim 11, wherein the return spring is set up in such a way that when the needle holder moves along the puncturing direction, the return spring can be pre-tensioned.

13. The placement aid according to claim 1, wherein a clamping element is arranged in a fastening section of the catheter, and wherein the clamping element forms a force-fitting connection with the placement needle.

14. The placement aid according to claim 1, wherein the holding-down rod is further arranged at the main body in such a way that upon reaching the subcutaneous end position of the catheter, the holding-down rod can be withdrawn from the catheter after the placement needle has at least partially been pulled out of the catheter.

15. The placement aid according to claim 14, wherein the holding-down rod comprises a plunger which is attached to the piston by mean of a force-fitting connection, and wherein the plunger is further arranged in the piston in such a way that, at a predetermined position in the piston, the needle holder presses against the plunger against the puncturing direction in such a way that the force-fitting connection between the piston and the plunger can be overcome and the plunger with the holding-down rod can be moved by means of the needle holder against the puncturing direction relative to the piston.

16. The placement aid according to claim 1, further comprising a support element which can be attached to the skin, wherein at least one of the main body and the placement device can be attached to the support element in a replaceable manner in such a way that the main body can be affixed with a predetermined puncture angle between the placement needle and the skin.

17. The placement aid according to claim 16, wherein the support element comprises a fastening element which is designed to fasten the catheter to the support element when the catheter is in the subcutaneous end position.

18. The placement aid according to claim 16, further comprising at least one of a sensor read-out unit, which can be attached in a replaceable manner to the support element in such a way that the sensor read-out unit is coupled to the sensor wire; and a pump unit for injecting a medication, wherein the pump unit can be attached at the support element in a replaceable manner in such a way that the pump unit is coupled to the catheter.

19. A method of placing a catheter in to a body with a placement aid according to claim 1, wherein the method comprises: arranging the replacement device in the placement device; applying the placement aid on a skin of the body; placing the catheter by means of the placement aid; and removing and replacing the replacement device from the placement device.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Below, for further explanation and for a better understanding of the present invention, forms of embodiment are described in more detail with reference to the attached figures. In these

(2) FIG. 1 shows a schematic view of a placement aid in accordance with an example form of embodiment of the present invention;

(3) FIGS. 2 to 6 show schematic cross-sectional views of a replacement device of a placement aid in accordance with an example form of embodiment of the present invention, where in FIG. 2 to FIG. 6 one placement cycle is shown;

(4) FIG. 7 shows a perspective view of a replacement device of the placement aid in FIG. 2 to FIG. 6;

(5) FIG. 8 to FIG. 11 show schematic cross-sectional views of a placement aid with a placement device and a replacement device in accordance with an example form of embodiment of the present invention, wherein in FIG. 8 to FIG. 11 a placement cycle is shown;

(6) FIG. 12 shows a perspective view of the placement aid in FIG. 8 to FIG. 11;

(7) FIG. 13 to FIG. 15 show schematic representations of a housing body or a placement device according to an example form of embodiment of the present invention;

(8) FIG. 16 shows a schematic representation of a fastening of a placement device with a main body and a piston of a replacement device in accordance with an example form of embodiment of the present invention, and

(9) FIG. 17A to FIG. 17C show schematic views of a support element with an adjustable catheter holder.

DETAILED DESCRIPTION OF EXAMPLE FORMS OF EMBODIMENT

(10) Identical or similar components are given the same reference numbers in the Figures. The views in the Figures are schematic and are not to scale.

(11) FIG. 1 shows a first example form of embodiment of the placement aid 100. The placement aid 100 comprises a main body 201 for supporting on the skin 101 of a body. The placement aid 100 also comprises a placement needle 203 and a catheter 205. The placement needle 203 is coupled to the main body 201. The placement needle 203 and the catheter 205 are arranged with regard to each other in such a way that the placement needle 203 is arranged within the catheter 205 and that a tip 102 of the placement needle 204 protrudes from a proximal end of the catheter 104 along a puncturing direction 103 so that upon placement of the catheter 205 along the puncturing direction 103 the tip 102 of the placement needle 203 penetrates the skin 101 in order to produce a skin opening 108 through which the catheter 205 is guided up to a subcutaneous end position. The catheter 205 is coupled to the placement needle 203 or by means of the placement needle 203 (indirectly) to the main body 201 in such a way that upon reaching the subcutaneous end position of the catheter 205 the placement needle 203 can be withdrawn against the puncturing direction 103 from the catheter 205 and the catheter 103 remains in the subcutaneous end position.

(12) More particularly, FIG. 1 shows a replacement device 200 or an infusion set or replacement set, e.g. the main body 201, the piston 202 (see FIG. 2), the placement needle 203, a needle holder 204, to which the placement needle 203 is attached, and the catheter 205. The replacement device 200 is, for example, arranged in a placement device 800 (see FIG. 8) in a replaceable manner (see FIG. 8).

(13) The placement needle 203 comprises a needle, which, for example, is made of metal or a similar hard material. With its tip 102 the placement needle produces a small cut in the skin in order to produce the skin opening 108. The skin opening 108 is widened or opened further by the remainder of the needle body and the subsequently guided catheter 205. The placement needle 203 is guided within the catheter 114.

(14) In FIG. 1 the placement needle 203 and the catheter 205 are shown in a subcutaneous end position, i.e. at a desired depth in the skin 101 or in the tissue 109. The subcutaneous end position describes the desired position of a proximal end of the catheter 205 or the puncturing depth of the catheter 205. The subcutaneous end position can be selected in each case of application so that a proximal end of the catheter 205 is present in the fatty tissue, the muscle tissue or within a blood vessel.

(15) As shown in FIG. 1, the main body 201 is a hollow-cylindrical body or a hollow-cylindrical tube, wherein the catheter 205 and the placement needle 203 are arranged within the main body 201. The placement needle 203 can be spatially fixed to the main body 201 or arranged in a displaceable manner at the main body 201.

(16) If the placement needle 203 is spatially fixed to the main body 201, the user can manually move the main body 201 together with the placement needle 203 and the catheter 205 in the puncturing direction in order to puncture the skin until the subcutaneous end position is reached.

(17) If the placement needle 203 is arranged at the main body 201 in a displaceable manner a displacement mechanism can be used. The user places the main body 201 on the skin 101 and activates the displacement mechanism so that the placement needle 203 together with the catheter 205 is moved in the puncturing direction until the subcutaneous end position is reached (see FIG. 1). The displacement mechanism is based, for example, on a spring-based mechanism. In FIG. 1 the placement needle 203 comprises a needle holder 204. The needle holder 204 is arranged within the main body 201 in a displaceable manner. Additionally, a first spring 106 is arranged between the needle holder 204 and the main body 201. The first spring 106 is set up in such a way that a first spring force F1 is exerted in the puncturing direction 103. By means of the first spring force F1 the needle holder 204 and the catheter 205 are moved along the puncturing direction 103 until the subcutaneous end position of the catheter 205 is reached. The first spring F1 can, for example, be initially pre-tensioned and held in position by means of a catch mechanism. The user can activate the displacement mechanism by releasing the first spring 106 so that the placement procedure is started.

(18) Alternatively or in addition to the first spring 106 a second spring 803, described below in FIG. 8, can be arranged between the placement device 800 of the placement aid 100 and the piston 202 of the replacement device 800 in such a way that a second spring force F2 of the second spring 803 acts along the puncturing direction 103 in order to, during the placement of the catheter 205, advance the needle holder 204 along puncturing direction 103 directly (or indirectly by means, for example, of the piston 202).

(19) The catheter 205 is coupled to the placement needle 203 in such a way that upon reaching the subcutaneous end position of the catheter 205 the placement needle 203 can be withdrawn from the catheter 205 contrary to the puncturing direction 103 and the catheter 205 remains in the subcutaneous end position.

(20) The placement needle 203 can, for example, be attached to the catheter 205 by means of an interlocking connection (e.g. with a hook or snap-type connection). The interlocking connection is released, for example automatically, i.e. upon reaching the subcutaneous end position, or by means of an unlocking mechanism, which can be operated by the user. Additionally, the placement needle 203 can be coupled to the catheter 205 by means of a force-fitting connection, wherein the placement needle 203 is coupled to the catheter 205 by means of frictional forces. When withdrawing the placement needle 203 the withdrawing force acting against the puncturing direction 103 exceeds the frictional force so that the placement needle 203 is released from the catheter 205 and can be pulled out. At the same time the frictional connection between the catheter 205 and the tissue surrounding the catheter 205 is larger than the withdrawing forces so that the catheter 205 remains in the subcutaneous end position.

(21) The placement needle 203 can be withdrawn from the catheter 205 after reaching the subcutaneous end position either manually or in a spring-based manner. As shown in FIG. 1 a return spring 107 can be arranged between the needle holder 204 and a section of the main body 201. A spring force Fr of the return spring 107 presses the needle holder 204 against the puncturing direction 103. After the catheter 205 reaches the subcutaneous end position a further mechanism can release the return spring 107 so that the needle holder 204, after reaching the subcutaneous end position together with the placement needle 203, is withdrawn from the tissue contrary to the puncturing direction 103.

(22) The catheter 205 comprises a fastening section 104, with which the catheter 205 can be attached to the placement needle 203, and a subcutaneous section 105. The subcutaneous section 105 can be at least partially introduced through the skin opening 108 into the skin 101 or tissue 109, wherein the fastening section 104 forms a (force-fitting or interlocking) connection with the placement needle 203.

(23) The fastening section 104 can for example be a membrane or clamping element 208 made of an elastic material, such as an elastic synthetic material (e.g. a silicone pad or silicone). The placement needle 203 can, for example, puncture the clamping element so that the clamping element 208 is elastically deformed and presses against the placement needle 203 with a certain adhesive force. In this way the frictional connection between the placement needle 203 and the catheter 205 is produced. When withdrawing the placement needle 203 from the catheter 205 the predetermined adhesive force is exceeded and the placement needle 203 is pulled out while the catheter 205 remains in its position.

(24) Further, the fastening section 104 can be used for a coupling with, for example, a support element 806 (see FIG. 8), sensor read-out units, insulin pumps or other functional devices.

(25) A sensor wire 210 can also be arranged in the placement needle 203. The sensor wire 210 is coupled to the placement needle 203 in such a way that when placing the catheter 205 along the puncturing direction 103 the sensor wire 210 is arranged in the placement needle 203 and that upon reaching the subcutaneous end position of the catheter 205 the placement needle 203 can be pulled out from the catheter 205 against the puncturing direction 103 and the sensor wire 210 remains in the catheter 205.

(26) The sensor wire 210 forms an electrode for example. During the placement of the catheter, the sensor wire 201 is, for example, held in position relative to the sensor needle 203 by means of a frictional connection in the sensor needle 203. Accordingly, the sensor wire 210 can be pressed against the inner surface of the placement needle 203 with a certain pressure force so that a friction force fixes the sensor wire 210 to the placement needle 203. When withdrawing the placement needle 203 the withdrawal force exceeds the frictional force fixing the sensor wire 210 to the placement needle 203 so that the placement needle 203 can be pulled out from the body relative to the sensor wire 210 and the sensor wire 210 remains in the subcutaneous end position.

(27) After placement of the catheter 205 and the sensor wire 210 the needle holder 204 together with the placement needle 203 can be completely retracted into the inner volume of the main body 201 and is thus insulated from the surroundings of the main body 201. In this way the risk of infection from the used placement needle 203 is reduced.

(28) FIG. 2 to FIG. 6 show perspective cross-sectional views of the replacement device 200 with a placement aid 100 according to an example form of embodiment of the present invention, wherein in FIG. 2 to FIG. 6 one placement cycle of the catheter 205 and a sensor wire 210 is shown.

(29) The placement aid 100 in FIG. 2 to FIG. 6 essentially comprises the same features as the placement aid 100 in FIG. 1. Additionally the placement aid 100 comprises a piston 202 which can be introduced into and retracted from the main body 201 in a telescopic manner. The needle holder 204 is coupled to the piston 202 in such a way that when moving the piston 202, the needle holder 204 together with the placement needle 203 and the catheter can be advanced in the puncturing direction 103 until the subcutaneous end position is reached (see FIG. 3).

(30) Upon reaching the subcutaneous end position the piston 202 and the needle holder 204 can be detached from one another and the needle holder 204 moves relative to the piston 202 contrary to the puncturing direction 103. The needle holder 204 thus moves into the inner volume of the piston 202 and is stored therein after placement of the catheter 205 (see FIG. 5).

(31) Decoupling the needle holder 204 from the piston 202 can take place by means of an interlocking (e.g. snap or click-type) connection. As shown in FIG. 2 to FIG. 6, the needle holder 204 can have a notch 211 and the piston 202 can have a snap hook 212. The needle holder 204 can also be elastically deformable so that it can be pressed together at a desired position in order to release the connection between the notch 211 and the snap hook 212. For example, the needle holder 204 can have a wedge-shaped surface 213 which, upon reaching the subcutaneous end position of the catheter 205, is pushed against a stop or a further wedge-shaped surface of the main body 201. The first wedge-shaped surface can, for instances, be formed accordingly at an inner side of the main body 201. When moving the needle holder 204 along the wedge-shaped surface the needle holder 204 is compressed in the region of its wedge-shaped surface 213 so that upon reaching the subcutaneous end position of the catheter 205 the needle holder 204 is disconnected from the snap hook 213 and the needle holder 204 moves into the inner volume of the piston 202. The pushing back of the needle holder 204 against the puncturing direction 103 after reaching the subcutaneous end position of the catheter 205 can take place by means of the return spring 107 for example.

(32) Additionally, in the placement aid 100 a holding-down rod 206 is shown in FIG. 2 to FIG. 6. The holding down rod 206 is arranged in the placement needle 203 in a displaceable manner. The holding down rod 206 is designed to frictionally press the sensor wire 210 against the placement needle 203 or the inner surface of the placement needle 203. The holding-down rod 206 can also be arranged at the main body 201 to be moved along the puncturing direction 103 so that when placing (moving) the catheter along the puncturing direction 103 the placement needle 203, the sensor wire 210 and the holding-down rod 206 can be jointly advanced to the subcutaneous end position in the tissue 109 (see FIG. 2 and FIG. 3) and that upon reaching the subcutaneous end position of the catheter 205 the holding-down rod 206 can be withdrawn from the catheter 205 contrary to the puncturing direction 103 (see FIG. 5, FIG. 6).

(33) The holding-down rod 206 reduces the free volume inside the placement needle 203 so that the sensor wire 210 is clamped between the holding-down rod 206 and the inner surface of the placement needle 203. In this way the holding-down rod 206 produces the pressing force of the sensor wire 113 on the inner surface of the placement needle 203. In particular, in this way the placement needle 203 can be withdrawn from the body without the holding-down rod 206 and the sensor wire 210 being pulled out so that they remain in the subcutaneous end position (cf. FIG. 4 with FIG. 5). Only after the placement needle 203 has at least partially been withdrawn from the body, the holding rod 206 can be removed from the body in a subsequent procedure and only the sensor wire 210 together with the catheter 205 remains in the body 205.

(34) This staggered removal of the placement needle 203 and the holding-down rod 206 is achieved in that the plunger 207 of the holding-down rod 206 is frictionally connected to the piston 202. The plunger 207 is arranged in the piston 202 in such a way that in a predetermined position in the piston 202 the needle holder 204 is pressed against the plunger 207 contrary to the puncturing direction 103 in such a way that the frictional connection between the piston 202 and the plunger 207 is overcome and the plunger 207 with the holding-down rod 206 is pushed against the puncturing direction 103 relative to the piston 202 by means of the needle holder 204 (see FIG. 5, FIG. 6).

(35) The predetermined position of the plunger 207 in the piston 202 is selected in such a way that the needle holder 204 initially withdraws the placement needle 203 from the body and presses against the plunger 207 only after the needle holder 204 has already been moved a certain distance in the piston 202 contrary to the puncturing direction 103. Thus, the holding-down rod 206 initially remains on the subcutaneous end position in the body along with the sensor wire 210, whereas a section of the placement needle 203 has already been withdrawn from the body.

(36) Furthermore, in FIG. 2 and FIG. 3 the catheter 205 is shown with the fastening section 104 and the subcutaneous section 105. The clamping element 208 is arranged in the fastening section 104. The clamping element 208 also comprises at least one contact surface 209. The contact surface 209 is, for example, itself elastically deformable or attached in the elastically deformable clamping element 208. The placement needle 203, which contains the sensor wire 210 within it, penetrates the elastically deformable clamping element 208. After the placement needle 203 has been withdrawn from the elastically deformable clamping element 208 and, accordingly, the catheter 205, the elastically deformable clamping element 208 closes the hole through which the placement needle 203 penetrated. After withdrawal of the placement needle 203 the sensor wire 210 is still located in this hole and the contact surface 209 presses on the contact wire 210 so that a conductive contact between the sensor wire 210 and the contact surfaces 209 is produced. Additionally, the contact surfaces 209 can be connected to a sensor read-out unit so that measuring signals of the sensor wire 113 can be read out.

(37) FIG. 7 shows a perspective view of the placement aid 100 in FIG. 2 to FIG. 6. The placement aid 100 shows the piston 202 and the main body 201 in an initial position. The main body 201 comprises a first gap/groove 701 which extends along the puncturing direction 103. In this first gap 701 the piston 202 can, for example, be movably guided (e.g. by means of guide bolts of the piston 202 guided in the first gap 701). The piston 202 comprises, for example, a second gap 702 which extends along the puncturing direction 103. In this second gap 702 the needle holder 702 can for example be movably guided (e.g. by means of guide bolts of the needle holder 204 guided in the second gap 702).

(38) FIG. 8 to FIG. 11 show perspective cross-sectional views of an placement aid 100 with a placement device 800 in accordance with an example form of embodiment of the present invention, wherein in FIG. 8 to FIG. 11 a placement cycle of the catheter 205 and the sensor wire 210 is shown.

(39) The placement aid 100 in FIG. 8 to FIG. 11 exhibits essentially the same features as in the placement aid 100 in FIG. 2 to FIG. 7. The replacement device 200 comprises the main body 201, the piston 202, the placement needle 203, the needle holder 204, to which the placement needle 204 is fastened, the sensor wire 210, and the catheter 205, wherein the replacement device 200 is arranged in the placement device 800 in a replaceable manner.

(40) In particular, the piston 202 and the main body 201 can be used in a replaceable manner in the placement device 800. The placement aid 100 comprises a hollow-cylindrical housing, for example.

(41) The placement aid 100 comprises, for example, a displacement mechanism for moving the piston 202, the placement needle 203 and the catheter 205. A second spring is arranged between the placement device 800 and the piston 202 of the replacement device 800 in such a way that a second spring force F2 of the second spring 803 acts along the puncturing direction 103 in order to, during the placement of the catheter 205, directly move the needle holder 204 along the puncturing direction 103 (or indirectly by means, for example, of the piston 202).

(42) During a displacement of the needle holder 205 against the puncturing direction 103 the second spring 803 is pre-tensioned. If, for example, the needle holder 204 is inserted into the placement device 800 along with the piston 202 and/or main body 201, during placement into the placement device 800 the second spring 803 can be automatically pre-tensioned. In this way the placement aid 100 is simply loaded a prepared for use.

(43) A locking element 805 (e.g. a locking hook) locks the piston in an initial position in which the second spring 803 is pre-tensioned. A trigger device 802 (e.g. pushbutton) is connected to the locking element 805 in such a way that upon operation of the trigger element 802, for example by a user, the locking element 805 releases the piston 202 and the piston 202 can be advanced with the needle holder 204 along the puncturing direction 103 by means of the second spring force F2 (cf. FIG. 8 with FIG. 9). With a third spring force F3 a third spring 804 can move the trigger element 802 back into a starting position.

(44) Upon reaching the subcutaneous end position of the catheter 205 (FIG. 9 to FIG. 11), by means of the return spring 107 the placement needle 203 is decoupled from the catheter 205 and is removed from the body against the puncturing direction 103. In interaction with the second spring 803 an automatic placement mechanism is thus provided. The user only has to operate, for example, the trigger element 802 in order to activate the placement aid 100. After operation of the trigger element 802 the piston 202 with the needle holder 204 and with the placement needle 203 together with the catheter 205 moves to the subcutaneous end position. The needle holder 204 is then removed from the body by way of the return spring 107 without the user having to take any further steps.

(45) Further, the main body 201 is attached in a replaceable manner to a support element 806 in such a way that the main body 201 is fixed between the placement needle 203 and the skin surface at a predetermined puncturing angle. The support element 806 can, for example, be attached to the skin 101 by means of an adhesive connection (e.g. by means of a plaster). The support element 806 comprises coupling elements, for example, which couple the main body 201 to the support element 806 in a replaceable manner. For example, the main body 201 can be fastened to the support element 806 by means of a bayonet connection.

(46) The support element 806 further comprises a fastening element or a catheter element 807 which is designed to connect the catheter 205 to the support element 806 when the catheter 205 is in the subcutaneous end position.

(47) The catheter holder 807 forms with the catheter 205 for instance a force-fitting or interlocking connection (e.g. a snap-hook connection). For example, the catheter holder 807 can form a bayonet connection with the catheter 205.

(48) The catheter holder 807 is, for example, arranged in a pivoting manner in the support element 806 and can be selectively locked in a desired pivoting position. The user can adjust the desired pivoting position in such a way that the catheter holder 807 holds the catheter 205 or the trigger device 200 and the placement device 800 in such a way that a desired first or second puncturing angle , can be set.

(49) The puncturing angle , defines an angle between the skin surface and the longitudinal axis of the placement needle 203. The puncturing angle , is, for example, between 0 and 90. The shallower the angle the closer the subcutaneous end position is to the skin surface. The steeper the angle, for example around 90, the deeper the subcutaneous end position is within the skin or the tissue.

(50) By means of being able to select the puncturing angle , the user can adapt the puncturing angle , to the thickness of his/her subcutaneous fat layer so that with a given catheter and sensor wire length the proximal ends of the catheter 205 and sensor wire 210 come to rest in the fatty tissue and do not extend into the underlying muscle tissue. The replacement set or the replacement device 200 can therefore advantageously be produced with a single catheter and sensor wire length.

(51) Upon reaching the subcutaneous end position the catheter 205 is decoupled from the main body 201. Accordingly, the main body 201 can be detached from the support element 806, wherein the catheter 205 remains fixed at the support element 806 and can be separated from the main body 201.

(52) FIG. 12 shows a perspective view of the placement aid 100 in FIG. 8 to FIG. 11.

(53) FIG. 13 to FIG. 15 show schematic representations of the housing body 801. The placement aid 100 comprises a hollow cylindrical shape. The trigger element 802 is arranged in a head region of the housing body 801. The trigger element 802 comprises a hollow-cylindrical form, wherein the trigger element 802 comprises an opening in the interior of the housing body 801. Upon displacement of the trigger element 802 in the puncturing direction 103 the trigger element 802 is pulled over the locking elements 805. The locking elements 805 are thereby pressed together and the second spring 803 is released. In this way the second spring 803 can exert the second spring force F2 on the piston 22 and move it in the puncturing direction 103. In FIG. 13 a return ring 808 is shown in which the piston 202 can be fastened in a replaceable manner. After operation of the trigger element 802, by way of the third spring force F3 the third spring 804 again presses the trigger element 802 into a starting position.

(54) FIG. 16 shows a procedure for fastening the placement device 800 to the replacement device 200, i.e. the main body 201 and the piston 202. The placement device 800 can be connected to the main body 201 of the replacement device 200 by means of a bayonet connection for example. In this way the piston 202 together with the main body 201 can be pushed into the housing 801 and fastened by way of a quarter or half turn. Accordingly, after placement of the sensor wire the piston 202 and the main body 201 can be detached from the placement device 800 by way of a quarter or a half turn. Accordingly, after placing the sensor wire, the piston 202 and the main body 201 can be removed from the placement device 800 by means of a quarter or half turn.

(55) The main body 201 can, for example, be connected to the support element 806 by mean of a bayonet connection. After placing the catheter 205 and the sensor wire 210 these remain fixed in the support element 806. The placement device 800 together with the replacement device 200 (more particularly with the main body 201 and the piston 202) can be detached from the support element 806. The catheter holder 807 can for example be attached to the support element 806 in a pivotable manner in order to adjust the puncturing angle.

(56) After the catheter 205 has been brought into the subcutaneous end position and has been fastened to the support element 806, the catheter 205 can be used for the further application. For example, at the sensor wire 210 the sensor read-out unit or a pump unit can be subsequently fastened to the catheter 205 for an infusion of a medication.

(57) The sensor read-out unit can be replaceably attached to the support element 806 in such a way that the senor read-out unit is coupled for signal exchange with the sensor wire 210, which is located in the catheter 205. Accordingly, a pump unit can be replaceably attached to the support element 806 in such a way that the pump unit is coupled to the catheter 205 so that a medication can be infused by the pump unit into the catheter 205 and thus be conveyed to the subcutaneous end position.

(58) FIG. 17a to FIG. 17c show schematic views of a support element 806 with an adjustable catheter holder 807. The catheter holder 807 is attached to the support element in a pivotable manner and can be locked or fixed in a desired pivoting position. The catheter 205 can be fixed in the catheter holder 807. In this way a desired puncturing angle , can be set by means of the catheter holder 807.

(59) FIG. 17C further shows that the catheter holder 807 can be folded into the support element 806 and is thus protected from surrounding influences. In the catheter holder 807 the catheter can be arranged isolated from the placement aid 100. The catheter 205 can thus initially be placed by means of the placement aid 100 and the placement aid 100 is then detached from the catheter 205 so that the catheter 205 is present in the catheter holder 807. If no medication is supplied or no measurement is carried out by means of the sensor wire 210, the catheter 205 together with the catheter holder 807 can be pivoted into the inactive, protected position, as shown in FIG. 17C.

(60) It is additionally pointed out that comprising does not rule out other elements or steps and a or an does not rule out a plurality. It is also pointed out that features or steps described with reference to one of the above examples of embodiment can also be used in combination with other features or steps of other examples of embodiment described above. Reference numbers in the claims should not be seen as restrictive.

LIST OF REFERENCE NUMBERS

(61) 100 Placement aid 101 Skin/tissue 102 Tip 103 Puncturing direction 104 Fastening section 105 Subcutaneous section of the catheter 106 First spring 107 Return spring 108 Skin opening 109 Skin 200 Replacement device 201 Main body 202 Piston 203 Placement needle 204 Needle holder 205 Catheter 206 Holding-down rod 207 Plunger 208 Clamping element 209 Sensor contact 210 Sensor wire 211 Notch 212 Snap hook 213 Wedge-shaped surface 701 First gap 702 Second gap 800 Placement device 801 Housing body 802 Trigger element 803 Second spring 804 Third spring 805 Locking element 806 Support element 807 Catheter holder 808 Return ring F1 First spring force F2 Second spring force F3 Third spring force Fr Return spring force , Puncturing angle