Method and device for controlling the introduction depth of an injection needle

[0002] This application claims the priority of PCT application PCT/CH97/00448, filed Nov. 27, 1997, which is incorporated herein by reference.

[0003] The invention relates to a method for controlling the introduction depth of an injection needle in accordance with the preamble of claim 1 and to an apparatus for implementing this method as it reads from claim 3.

[0004] With conventional injection devices there is often the problem that the operator—the nurse or the patient—is unable to control, unaided, the introduction depth of the needle. Where a slender child is concerned, in comparison to a corpulent grown-up, a substantially shorter introduction depth suffices. If the injection needle is inserted unnecessarily deep in the tissue skin, pain materializes which is avoidable. In particular, in the case of patients who often have to endure frequent injections, e.g. diabetics, this leads to an aversion to or even a fear of the next injection.

[0005] The present invention is thus based on the object of providing a method and an apparatus for controlling the introduction depth of an injection needle by means of which the user is able to set the optimal introduction depth for the nature of the skin tissue concerned.

[0006] The invention achieves this desired object by providing a method, comprising the features of the characterizing part of the independent claim 1, and an apparatus, comprising the features of the characterizing part of the independent claim 3.

[0007] Due to the shortening of the maximum possible travel H of the injection needle by a spacer, it is possible to vary the introduction depth. This may be done either by a series of spacers differing in axial length x or by a frontal screw-on type spacer. The hollow-cylindrical spacer, arranged concentrically about the injection needle, may be simply snapped or clicked into the needle introduction device used, or be set by frontal screw-mounting to the desired introduction depth.

[0008] The needle introduction device is configured either as a separate unit for coupling to a conventional injection device or it may be integrated in the injection device.

[0009] When no spacer is clicked into the needle introduction device, or if the frontal screw-mounting spacer is in its resting position, then the maximum possible travel of the injection needle is permitted to thus attain the deepest introduction depth. If a spacer is click-mounted or screw-mounted into the travel of the injection needle, then the maximum travel H is shortened by the amount x and a shorter introduction depth results.

[0010] In a preferred embodiment of the invention, the needle introduction device is a separate unit which can be coupled to a conventional injection device, this unit comprising a rear longitudinal part including a piercing needle (which can be coupled to the injection device) and a front longitudinal part including an injection needle for delivery of the fluid into the tissue skin or subcutaneously. Provided between the piercing needle and the injection needle is a flexible connection.

[0011] The needle introduction device is connectable via the piercing needle to the pen cartridge of the injection device so that the fluid to be delivered into the tissue skin or subcutaneously is injectable via the injection needle and the procedure of introducing the injection needle into the tissue skin or subcutaneously automatically occurs upon manual activation of a control element of the needle introduction device, accommodated in the rear longitudinal part, and the fluid can be administered via the injection device.

[0012] Serving as the control element is an initiator sleeve arranged longitudinally shiftable on a piercing needle mount mounting the piercing needle and cooperates with an injection needle mount, likewise longitudinally shiftable in a stopper sleeve, mounting the injection needle.

[0013] Introducing the injection needle into the tissue skin or subcutaneously after manual activation of the initiator sleeve occurs in that the injection needle mount together with the injection needle is automatically moved by means of the force of a spring in the direction of the tissue skin. Following automatic introduction of the injection needle into the tissue skin or subcutaneously, the user is able to administer the dose of fluid required by means of the conventional injection device.

[0014] The apparatus in accordance with the invention has the salient advantage that it offers highly reliable assurance in controlling the introduction depth of the injection needle into the tissue skin or subcutaneously.

[0015] Further advantageous aspects of the invention read from the dependent claims.

[0016] An example embodiment of the invention is illustrated in the Figures in which:

[0017] FIG. 1: is a longitudinal section through an apparatus in accordance with the invention prior to insertion of the spacer, the needle introduction device being in the starting position or resting position;

[0018] FIG. 2: is a longitudinal section through the apparatus in accordance with FIG. 1 after insertion of the spacer;

[0019] FIG. 3: is a cross-section taken along the line III—III as shown in FIG. 2;

[0020] FIG. 4: is a longitudinal section through the apparatus in accordance with FIG. 2 in the safety release position after removal of the safety cap;

[0021] FIG. 5: is a longitudinal section through the apparatus in accordance with FIG. 2 after manual activation of the initiator sleeve;

[0022] FIG. 6: is a longitudinal section through the apparatus in accordance with FIG. 2 (including spacer) after actuating the travel of the needle introduction device;

[0023] FIG. 7: is a longitudinal section through the apparatus in accordance with FIG. 1 (without spacer) after actuating the travel of the needle introduction device;

[0024] FIG. 8: is a partial longitudinal section through an apparatus in accordance with the invention including a screw-mounting spacer; and

[0025] FIG. 9: is a cross-section taken along the line II—II as shown in FIG. 8.

[0026] Referring now to FIG. 1 there is illustrated a needle introduction device 17, 18 for injecting a fluid. The needle introduction device 17, 18 comprises substantially a rear longitudinal part 17, including a piercing needle 2, and a front longitudinal part 18, including an injection needle 1 for delivering the fluid into the tissue skin or subcutaneously, as well as a flexible connection 5 between the piercing needle 2 and the injection needle 1.

[0027] The needle introduction device 17, 18 can be coupled to the conventional injection device 12, for example, by a screw lock or by a latch cam mount 23 (FIG. 2). Via the piercing needle 2 provided at one end of the needle introduction device 17, 18, the needle introduction device 17, 18 is connected to the pen cartridge 13 of the conventional injection device 12. Via the injection needle 1 provided at the other end of the needle introduction device 17, 18, the fluid is injectable into the tissue skin or subcutaneously. Provided between the piercing needle 2 and the injection needle 1 is the flexible connection 5 for fluid transport. The procedure of introducing the injection needle 1 into the tissue skin or subcutaneously occurs automatically after manual activation of a control element in the form of the initiator sleeve 9 of the needle introduction device 17, 18, after which, the fluid can be administered via the conventional injection device 12. The initiator sleeve 9 is arranged longitudinally shiftable on the piercing needle mount 4 mounting the piercing needle 2 and cooperates with the injection needle mount 3, likewise longitudinally shiftable in the piercing needle mount 4 and in the stopper sleeve 7, said injection needle mount 3 mounting the injection needle 1. Introduction of the injection needle 1 into the tissue skin or subcutaneously occurs after manual activation of the initiator sleeve 9 by means of the force of the spring 6, in that the injection needle mount 3 together with the injection needle 1 is automatically moved against the tissue skin. In this way, the spring 6 is supported at its one end by the fixed piercing needle mount 4 and moves with its other end the injection needle mount 3 including the injection needle 1 in the direction of the tissue skin into which the injection needle 1 is automatically introduced. The cooperation of the initiator sleeve 9 and the injection needle mount 3 during manual activation of the initiator sleeve 9 occurs via the bevel tapers 14 by which the injection needle mount 3 is squeezed diametrically to thus defeat the lock consisting of the stopper 15 of the stopper sleeve 7 and the mounting cams 10′, 10″ of the injection needle mount 3 and thereby enabling the spring 6 to develop its urging effect. The injection needle mount 3 together with the injection needle 1 is automatically moved after manual activation of the initiator sleeve 9 by means of the force of spring 6 so long in the direction of the tissue skin until the face 11′ of the injection needle mount 3 comes up against the face 11″ of the stopper sleeve 7. On completion of injection, the injection needle mount 3 with the injection needle 1 is manually retractable by means of the safety cap 8, surrounding the stopper sleeve 7, against the force of the spring 6 until the lock consisting of the stopper 15 of the stopper sleeve 7 and the mounting cams 10′, 10″ of the injection needle mount 3 is again effective. At the same time, the initiator sleeve 9 is longitudinally shiftable by means of the bevel tapers 14 in the direction of the conventional injection device 12 by the safety cap 8 so that the initiator sleeve 9 is retracted into the starting position or resting position and is ready for a repeat manual activation. For retracting the injection needle mount 3 with the injection needle 1 by means of the safety cap 8, the latter is provided in its interior with a protective cylinder 16 surrounding and protecting the injection needle 1. The protective cylinder 16 also has the function that its open end contacts the face 11′ of the injection needle mount 3 and thus, when the safety cap 8 is shifted into the condition protecting the injection needle 1, it retracts the injection needle mount 3 together with the injection needle as well as the initiator sleeve 9 into the starting position.

[0028] The functioning of the needle introduction device 17, 18 in accordance with the invention will now be described:

[0029] The needle introduction device 17, 18 is mechanically coupled to the conventional injection device 12 by e.g. a screw lock or by a latch cam mount or similar, the piercing needle 2 piercing the pen cartridge septum to ensure that the fluid to be injected communicates with the needle introduction device. The user then brings the latter to the preferred tissue skin location before then activating the initiator sleeve 9 by pushing it longitudinally down in the direction of the tissue skin until the lock consisting of the stopper 15 of the stopper sleeve 7 and the mounting cams 10′, 10″ of the injection needle mount 3 is defeated. This enables the spring 6 to develop its force and automatically urge the injection needle mount 3 with the injection needle 1 in the direction of the tissue skin until the face 11′ of the injection needle mount 3 comes up against the face 11″ of the stopper sleeve 7, as a result of which the injection needle 1 is automatically introduced into the tissue skin. Now, the user is able to deliver the dose of fluid to be administered by means of the conventional injection device 12. On completion of injection, the injection needle mount 3 with the injection needle 1 is by means of safety cap 8, surrounding the stopper sleeve 7, manually retractable against the force of the spring 6. The lock is again effective and, at the same time, the initiator sleeve 9 returns to its starting position or resting position.

[0030] The piercing needle mount 3 may be preferably slotted in the region of the bevel tapers 14 to improve its elasticity when it is squeezed in cooperating with the initiator sleeve 9 during activation to defeat the lock.

[0031] Referring now to FIGS. 2 and 3, there is illustrated the needle introduction device 17, 18 in which a hollow-cylindrical spacer 21 is click-mounted concentrically about the injection needle 1 in the front longitudinal part 18 where it is secured in place. For this purpose, the spacer 21 comprises a peripheral undercut 22. Once fitted, the spacer 21, which is preferably made of a plastics material, remains in the needle introduction device 17, 18 provided as an instrument for once-only use and is thus disposed of along with the former.

[0032] FIG. 4 illustrates a longitudinal section of the needle introduction device 17, 18 in the released condition after removal of the safety cap 8. Except for this safety cap 8, FIG. 4 is substantially identical to FIG. 2 The reference numerals are identical in both figures.

[0033] FIG. 5 shows a longitudinal section of the needle introduction device 17, 18 after manual activation of the initiator sleeve 9. It is evident from this figure how, directly after defeating the lock, consisting of the stopper 15 of the stopper sleeve 7 and the mounting cams 10′, 10″ of the injection needle mount 3, due to cooperation of the bevel tapers 14 of the injection needle mount 3 and initiator sleeve 9, the injection needle mount 3 is flexibly squeezed so that the spring 6 can develop its force and automatic introduction of the injection needle 1 in the tissue skin or subcutaneously can commence.

[0034] In contrast to the needle introduction device having no inserted spacer 21, in this case, the injection needle mount 3 can be advanced only up to the face 11′″. The result of this is that the introduction depth is of varying shortness. As evident from FIGS. 6/7, the face 11′ of the injection needle mount 3 abuts against the face 11″ of the stopper sleeve 7 earlier due to insertion of the spacer 21 (FIG. 6), i.e. by the distance x between the face 11′″ and face 11″. Accordingly, with an inserted spacer 21 (FIG. 6), the introduction depth is H-x, as compared to the situation shown in FIG. 7 without spacer where the introduction depth is H.

[0035] Finally, FIGS. 8 and 9 illustrate a further embodiment of the invention in which the spacer 21 comprising a male thread 24 is frontally screw-mounted into the female thread 25 of the stopper sleeve 7 to thus make a variable shortening of the needle travel possible.

[0036] The apparatus in accordance with the invention is applicable for administering medications preferably. However, it may also be used in all applications in which a fluid is to be injected into a body and the injection needle is required to be inserted with automatic control of the introduction depth of the injection needle.