WO2005044116A2

WO2005044116A2 - Cutting device for blunt needle

Info

Publication number: WO2005044116A2
Application number: PCT/DK2004/000769
Authority: WO
Inventors: Kristian GLEJBØL; Peter Kaastrup
Original assignee: Novo Nordisk A/S
Priority date: 2003-11-07
Filing date: 2004-11-05
Publication date: 2005-05-19
Also published as: WO2005044116A3

Abstract

A cutting device for a blunt needle or transcutaneous sensor for insertion through the derma of a patient; said blunt needle or transcutaneous sensor having a circumference at the distal end; said cutting device comprising a base part and a cutting member for making an incision in the derma; said base part having a track adapted for slideable engagement with the needle or transcutaneous sensor, wherein the cutting member has a cutting width, W, being less than half the length of the circumference of the blunt needle or transcutaneous sensor.

Description

Cutting Device for Blunt Needle

Technical field

The present invention relates to a cutting device for a blunt needle for injection of a medical fluid or for insertion of a subcutaneous device into the human body. The invention further relates to a transcutaneous sensor insertion set for partly insertion of a transcutaneous sensor into the subcutis.

The skin is constituted by a series of layers. In brief the outmost layer is a tough, leathery layer, the derma or corium. Under the derma is a soft, fragile layer, subcutis, that contains a fine network of blood vessels and nerve connections. When injections of active medical compounds e.g. insulin are performed, the subcutis is often the target layer. This is also often the case when inserting sensors in the body, e.g. for measurement of blood glucose level.

To perform an injection, or to insert a sensor, the derma needs to be penetrated to provide access to the subcutaneous layer. Typically, for this purpose a needle with a cutting edge is utilized. When such a needle enters the subcutaneous tissue, the cutting edge will cause lesions to this tissue; cells are punctured, the fine blood vessels are damaged and nerve connections are cut, causing haemorrhage and trauma to the patient. Further, such haemorrhage triggers an immune reaction in the tissue, causing the chemical environment in the skin at the insertion site to change. This can influence the effect of the injected substance, which of course is highly undesirable. In the case of inserted sensors an altered chemical environment might influence the precision of the measurement. In the longer term the lesions may accelerate the generation of a fibrous encapsulation around the sensor, further influencing the precision of measurement. To avoid lesions of the subcutaneous tissue blunt, non-cutting infusion needles are utilized, e.g. needles with a rounded tip. When such a needle is forced through the subcutis the tissue will be gently parted instead of being cut. Thus the immune response is minimized, and the formation of scar tissue is impeded.

Consequently, the problem of bringing the blunt needle through the derma arises, since the blunt needle cannot cut this tough, leathery tissue.

In prior art devices for medical infusion this problem is solved by inserting a blunt infusion needle into e.g. a conventional needle with a cutting edge, and then inserting the pair forcing the cutting edge of the outer needle through the derma. Upon penetration of the derma the sharp needle is halted. Thus the derma is penetrated. Thereupon the blunt needle is slit through the inner lumen of the outer needle to a position extending beyond the tip of the outer needle, and into the subcutaneous tissue where the dose of medicine is delivered.

Alternatively, a short cutting needle provided on a cuff or sleeve being slideably arranged on a blunt needle has been utilized for this purpose. Such prior art devices are known from US-A-3,530,492 and US-A-3,840,008, which disclose arrangements for hypodermic injections.

These prior art sleeves comprise a short obliquely cut needle and a flange. The length of the cutting needle is sufficient to penetrate the derma. The flange constitutes a surface for abutment against the skin that will prevent the progression of the cutting needle into the subcutis. In use the sleeve is initially held at position at the distal end of the blunt needle, with the cutting needle extending beyond the distal blunt tip of the blunt needle. The cutting needle is then forced forward, penetrating the derma until the flange abuts on the outer surface of the skin halting the advancement of the cutting needle. Further advancement of the blunt needle will force the sleeve to slide in relation thereto, towards its proximal end, letting the blunt needle proceed into the subcutan layer, where it can deliver the desired volume of medicine.

However, these devices have some unfortunate drawbacks. When a conventional obliquely cut needle penetrates the skin, the foremost point/tip will first cut the derma. Then, as the needle tip progresses further into the skin, the so-called heel of the needle tip will further cut the tissue, causing additional pain and trauma. It is the heel of the needle that inflicts the majority of the damage to the skin.

Typically, needles used for inserting transcutaneous sensors are pushed into the tissue so that the sharp end of the needle penetrates the subcutaneous tissue in a depth corresponding to the desired sensor site. This procedure is associated with the drawback that one or more of the sensor electrodes is located in immediate contact with tissue that has been damaged by the sharp tip of the needle.

Prior art devices related to transcutaneous sensor insertion are disclosed in US-A-5,568,806 and US-A-5,779,665 and US-B1 -6,695,860. US-B1- 6,175,752 describes a further embodiment where a sensor is provided with a sharp point or a sharp edge to aid implantation without an additional insertion device. Such a configuration is associated with the same drawbacks with respect to damage and skin irritation due to the pointed tip or sharp edge of the sensor cutting the tissue both during insertion of the sensor as well as for the entire duration of sensor measurement.

US-B1 -6,436,068 shows an implantation instrument for subcutaneously implanting of sensors. The disclosed device shows a clearing trocar which can be used prior to sensor insertion for clearing a subcutaneous site prior to delivery of the implant. Object of the invention

It is an object of the present invention to provide a cutting device for a blunt needle that will lessen the discomfort of the patient and minimize the damage to the affected tissues and minimize the immune response by making the smallest possible damage to the skin.

It is also an object of the invention to provide a cutting device that can be used in combination with a blunt insertion needle for the insertion of sensors.

It is a further object of the invention to provide a cutting device for a blunt insertion needle for insertion of a subcutaneous device such as a sensor that will lessen the discomfort of the patient, minimize the damage to the affected tissues and minimize the immune response and impede encapsulation of the sensor by making the smallest possible damage to the skin.

It is a further object of the invention to provide a transcutaneous sensor insertion set, which minimizes skin damage during insertion of the transcutaneous sensor.

It is a further object of the invention to provide a method for insertion of a transcutaneous sensor whereby damage and skin irritation are minimized, and whereby accurate and reliable sensor measurements can be obtained.

It is a further object of the invention to provide a low-cost, easy-to- manufacture cutting device. It is a further object of the invention to provide a cutting device minimizing the risk of unintentional cuts subsequent to an injection or insertion.

Summary of the invention

The object of the invention is achieved by a combination of a cutting device and a blunt needle for insertion through the derma of a patient; said blunt needle having a circumference at the distal end; said cutting device comprising a base part and a cutting member for making an incision in the derma; said base part having a track adapted for slideable engagement with the blunt needle, wherein the cutting member has a cutting width being equal to or less than half the length of the circumference of the blunt needle.

The present invention is based in the realization that when the foremost point of the cutting needle has initially cut the derma no further cutting is needed. It is only necessary to perform a single small cut. The blunt needle will do the rest parting the skin and creating a channel to the underlying layers.

In an embodiment of the invention the cutting member is arched along the circumference of the blunt needle. Thus a stable cutting member is obtained.

Preferably the cutting device has an arched cutting member covering an angle of 180° or less.

The cutting device more preferably has an arched cutting member covering an angle greater than or equal to 5° and less than 180°.

The cutting device more preferably has an arched cutting member covering an angle of approximately 120°. In one embodiment the base part of the cutting device further comprises a recess extending from an outer surface to the track of the base part. Thereby it is obtained that the cutting device can be used in combination with an insertion needle for inserting a subcutaneous device such as a sensor or a catheter, allowing release of communication means extending from the subcutaneous device to the outside of the body.

In a further embodiment means for securing alignment of the recess in the cutting device and a track in the blunt insertion needle are disposed on the blunt insertion needle and the cutting device. Thus, it is secured that the sensor can easily be released from the blunt insertion needle, avoiding twisting or turning of the cutting device and/or the blunt needle when the combination is inserted into the skin of a patient.

Preferably the means for securing alignment comprise a tap on the cutting device and a complementary longitudinal groove in the insertion needle. Thus the alignment is achieved by very simple, cost-efficient means.

Preferably the cutting member is formed from stainless steel.

In a further embodiment the cutting device comprises locking means complementary to locking means on the blunt needle for locking the cutting device to the proximal end of the blunt needle. Thus, the cutting device can be prevented from injuring the patient or medical staff performing the injection or insertion after the injection or the insertion of a sensor.

According to an alternative embodiment, a transcutaneous sensor insertion set is provided where the insertion set comprises a sensor having a distal segment arranged for insertion into the subcutis and a proximal segment for placement ex-vivo and where a cutting device is used for puncturing the epidermis and dermis facilitating insertion of the distal segment of the sensor into the subcutaneous tissue without damaging said subcutaneous tissue with the cutting device.

Description of the drawings

The invention will be described in detail in the following with reference to the drawings in which

- FIG. 1 is a partly sectional view of a blunt injection needle with a cutting device according to a first embodiment of the invention as inserted into the derma;

- FIG. 2 is a partly sectional view of the blunt needle with the cutting device depicted in figure 1 in the situation where the needle is being retracted upon use;

- FIG. 3A is detailed perspective view of a cutting device;

- FIG. 3B is a front view of the cutting device of FIG. 3A;

- FIG. 4 is a front view of an alternative embodiment of the cutting device;

- FIG. 5 is a perspective view of a sensor and a blunt insertion needle for inserting sensors;

- FIG. 6 is a perspective view of a cutting device for a blunt insertion needle for inserting sensors; - Fig. 7 is a partly sectional view of a transcutaneous sensor insertion set with a cutting device inserted into the derma and with the sensor in its insertion state; and - Fig. 8 is a partly sectional view of the cutting device of Fig. 7, after insertion of the sensor into subcutis.

It should be noted that the figures are schematic and not necessarily drawn to scale, and that they represent exemplary embodiments of the invention only.

Detailed description of embodiments of the invention

Fig. 1 shows a section through the skin and a hollow blunt needle 10 with a cutting device 20. A sharp edge, pointed-tip cutting member 30 is provided on the cutting device 20.

The hollow blunt needle 10 comprises a distal 11 end; a proximal end 12; a needle body there between; and a lumen 14 there through for delivering or extracting a fluid. An outlet/inlet for the lumen 14 is arranged in the vicinity of the distal end 11. At the distal end 11 the needle 10 is provided with a blunt non-cutting tip 13. The proximal end 12 of the needle 10 is connected to a needle hub 15. The needle hub 15 is intended for mounting the needle on a syringe or injection apparatus (not shown).

On the needle 10 a cutting device 20 is arranged. The cutting device 20 is adapted to slide on the needle 10 along the longitudinal axis thereof.

Now referring to fig. 3A, the cutting device 20 has a base part 21 in the form of a sleeve with an opening or track 22 for engaging the blunt needle 10. The track 22 is adapted for sliding on the needle 10. Extending from the base part 21 adjacent to the track 22, and in extension thereof, a knife- or bayonet-like cutting member 30 is connected. The proximal end 32 of the cutting member 30 is connected to the base part 21. The distal end 31 of the cutting member 30 preferably has a pointed tip 33 adapted for making an incision in the skin, and it may be provided with sharpened cutting edges 34 at least along part of the edges 34 at the distal end 31. The sleeve 21 further comprises a distally facing surface 24 adapted for abutment against the outer surface of the skin. Alternative means for preventing the cutting device (20) to be advanced further into the subcutis will be readily apparent by the skilled reader. Such means may include any mechanical structure which will limit the cutting depth with respect to the distance from the surface of the skin.

The cutting member 30 is preferably a knife- or bayonet-like member, arranged generally perpendicular to the surface 24, having a largest width W at the base of the cutting member 30 closest to the base part 21. The width W is indicated in fig. 4 showing an embodiment of the cutting device 20 where the cutting member 30 has a generally planar shape. It will be appreciated that the cutting member 30 in the curved embodiment shown in fig. 3 has a corresponding width W taken along its curved surface. The cutting member 30 preferably has generally parallel edges 34 along a majority of a body portion of the cutting member 30, tapering into a pointed tip 33 at the most distal end 31 thereof. Alternatively the cutting member 30 has a generally tapering width towards the distal end 31 as shown in fig. 3A.

During use the cutting device 20 is initially situated at the distal end 11 of the blunt needle, with the cutting member 30 extending distally and beyond the tip 13 of the blunt needle 10. The base part 21 is preferably in frictional engagement with the blunt needle 10, the friction holding the cutting device in place at the distal end 11 thereof. The assembly comprising the blunt needle 10 and the cutting device 20 is forced towards the skin, the tip 33 and edges 34 of the cutting member creating a small incision in the cutis providing a passage through the derma 1 for the blunt needle 10, as shown in fig. 1. The friction between the blunt needle 10 and the track 22 of the base part 21 is arranged to be greater than the force necessary for cutting through the derma 1. Pressing further, the tip 13 of the blunt needle 10 will gently part the tissue creating a temporary path or channel through the derma 1 and into the subcutis 2. The progress of the cutting member 30 will be halted by the distally facing surface 24 of the base part 21 when abutting the outer surface 3 of the skin, as shown in fig. 1. The length of the cutting member 30 is adapted to correspond with the average thickness of the derma 1. Thus it is ensured that the cutting member 30 will not damage the underlying subcutaneous layer 2.

Urging the needle 10 onwards, the tip 13 will gently part the tissue in the subcutaneous layer 2 until the desired depth has been reached, and a dose of medicine can be delivered through the lumen 14 of the needle 10. Thus, the cutting member 30 is displaced relative to the needle 10 and towards the proximal end 12 thereof.

As described above, preferably, the base part 21 is initially held to the distal end 11 of the blunt needle 10 by the force of friction. However, other means for temporarily holding the cutting device 20 at the distal end 11 of the blunt needle 10 could be utilized, e.g. a flexible arm (not shown) disposed between the needle hub 15 and the base part 21 , said flexible arm having resilient properties urging the cutting device 20 towards the distal end 11 of the blunt needle 10.

In fig. 1 as well as in fig. 2 the blunt needle 10 is shown in a position perpendicular to the surface of the skin. However, the insertion can also be performed at an angle different than 90° relative to said surface 3 of the skin. Turning now to fig 3B showing a schematic frontal view of a cutting device 30, it will appear that the cutting member 30 is arranged generally adjacent to the needle track 22, allowing a close contact between the cutting member 30 and the blunt needle 10 (when in a retracted position). The cutting member 30 is preferably shaped in an arch to follow the curving of the blunt needle 10 and the track 22 complementary to the blunt needle 10; and it covers an angle α along this curving, between the edges 34 of the cutting member 30. The most advantageous angle will depend on the thickness of the material constituting the cutting member 30. Using a thicker material, a smaller angle can be applied for obtaining the same length of a cut and vice versa. This is because a thicker cutting member 30 will push the tissue further apart. The angle α, however, has to be less than 180° in order to avoid the unnecessary extra cut that the heel of a cutting member with an angle α larger than 180° will inflict. The angle α is preferably between 5° and 180°. In an especially advantageous embodiment the angle α is approximately 120°. At α=180° the cutting member 30 is comparable to a regular needle without a heel, i.e. a needle cut in half along its longitudinal axis.

In an alternative embodiment the cutting member 30 can be formed with a generally planar shape, resembling a blade of a conventional knife, as illustrated in fig. 4. Since the purpose of the cutting device 20 according to the invention is to make as little damage as possible by making the smallest possible incision it is important that the cutting width, W, i.e. the distance between the edges 34 of the cutting member 30 is less than half the length of the circumference, C, of the blunt needle 10. This is also the case in the preferred embodiment where the cutting member 30 is arched as shown in fig 3. In the case of a planar cutting device 30, more specifically, the cutting width, W, is preferably less than half the diameter of the blunt needle 10. Thus, the cutting member 30 is, in any of the above described embodiments, formed entirely in a single half-plane of the surface 24 of the base member, such that at least a heel on the cutting member 30 can be avoided. This could also be described such that the cutting member 30 needs to be formed entirely on one side of a plane C defined as being parallel to, and congruent with the longitudinal axis through the centre of the blunt needle 10 (or the complementary track 22) on which the cutting device 20 is slideably arranged. The plane C is shown in fig. 1.

The arched form of the cutting member 30 in the preferred embodiment has the further advantages that even for use with very small needles 10, where very thin material has to be used for the cutting member 30 the sufficient rigidity of the cutting member can be obtained.

The needle hub 15 or the proximal end 12 of the needle 10 and the cutting device 20 can advantageously be provided with corresponding locking means 16, 23 to automatically lock the position of the cutting device 20 at the proximal end 12 of the blunt needle 10 upon the insertion of the blunt needle into the subcutaneous layer, as shown in figs.1 and 2. Thus it is secured that the sharp cutting member 30 cannot unintentionally cut the patient or a person performing an injection on a patient when the assembly is withdrawn from the patient, subsequent to an injection (or insertion of a sensor as described below), and the assembly can easily be discarded without risk of injury.

Such locking means could e.g. be constituted simply by a stud 16 with a hook on the needle hub 15, and a corresponding notch 23 on the base part 21 of the cutting device 20. The locking means alternatively could be comprised by a tap (not shown) on the proximal end 12 of the blunt needle 10 and a recess (not shown) formed within track 22 of the base part 21. In figure 2 the blunt needle 10 with the cutting device 20 secured to the proximal end 12 of the blunt needle 10 is shown being retracted after the injection has been performed.

Conventionally, in the prior art, the blunt needle 10 is formed from metal, and the needle hub 15 is formed from a polymer. Likewise the present base part 21 can be formed from a polymer and the cutting member 30 can be formed from a metal. However, the cutting device 20 of the present invention will allow the blunt needle 10 to be formed by a polymer, since a cutting tip is no longer needed on the needle 10. Alternatively, all parts can be made from a metal or metal alloy. Also, all parts can be formed by a polymeric material, the requirement of course being that a sufficiently sharp and durable point/edge on the cutting member 30 can be accomplished. Since only the distal tip 33 of the cutting member 30 needs to be sharp, a sufficiently sharp and durable cutting member can be formed from a polymer. Alternatively, the cutting member can be made from a metal, a metal alloy, a ceramic material, a composite of a metal and a polymer, or a composite of a ceramic material and a polymer. In a preferred embodiment the sleeve is made from a polymer and the cutting member is made from stainless steel, resulting in very low manufacturing cost.

Figs. 1-4 show embodiments of the invention relating to injection of a fluid medicine, e.g. insulin. Besides, the invention can advantageously be used in relation to the insertion of a subcutaneous device, such as an implantable sensor, a transcutaneous sensor, or a catheter into a human or animal body.

Fig. 5 shows a blunt needle 40 adapted for insertion of a subcutaneous device. The blunt insertion needle 40 has a distal end 41 and a proximal end 42 and a body there between. At the distal end 41 the tip 43 is blunted, i.e. non-cutting. The needle 40 is further provided with a track or groove 44 at least along a part of the needle body for receiving a subcutaneous device 70. Due to the track 44 the needle 40 has an essentially U-shaped cross section. The track 44 enables the placement of a subcutaneous device 70 that needs to be in communication with the outside of the body e.g. via a tubing or via electrodes. The proximal end 42 of the needle 40 is connected to a needle hub (not shown) or an insertion apparatus (nor shown). The needle hub or the insertion apparatus is provided with a recess complementary to track 44.

In figure 5 the subcutaneous device 70 is shown in a principle outline. Communication means (not shown) allowing the subcutaneous device to be in communication with the outside after being inserted into a body, e.g. a tube or set of electrodes could be extended in the proximal direction from the subcutaneous device 70. In the figure the track 44 is extended to and through the distal tip 41 of the insertion needle 40. However, the distal end 41 could be closed having a rounded tip, the track 44 e.g. terminating in a proximally faced ramp or surface for ejecting the subcutaneous device 70 sideways in relation to the longitudinal axis of the insertion needle 40.

Fig. 6 shows a cutting device 50 for use with a blunt insertion needle 40 as shown in fig. 4 and as described above. The cutting device 50 has a cutting member 30 similar to the cutting member 30 in the embodiments shown in figs. 1-4. The cutting device 50 has a base part 51 in the form of a sleeve with a track 52 for engaging the blunt needle 40. The track 52 is adapted for sliding on the needle 40. Extending from the base part 51 adjacent to the track 52, and in extension thereof, a knife- or bayonet-like cutting member 30 is connected. The proximal end 32 of the cutting member 30 is connected to the sleeve 51. The distal end 31 of the cutting member 30 preferably has a pointed tip 33 and it may be provided with sharpened cutting edges 34 at least along part of the edges at the distal end 31. The base part 51 further comprises a distally facing surface 54 adapted for abutment against the outer surface of the skin 3. A longitudinal recess 56 is formed in the base part 51 of the cutting device 50 from an outer surface 57 of the base part 51 to the track 52. The longitudinal recess 56 is adapted to communicate with the track 44 in the blunt insertion needle 40 when aligned with track 44. Thus the recess 56 and the track 44 of the blunt needle 40 allows a subcutaneous device 70 or the communication means for the subcutaneous device 70 to be removed from the track 44 in a radial direction with respect to the longitudinal axis of the insertion needle 40.

The blunt insertion needle 40 and the cutting device 50 can be equipped with means (not shown) for securing the alignment of the recess 56 in the cutting device 50 with the track 44 in the blunt insertion needle 40, e.g. in the form of a tap formed on the surface of the track 52 of the cutting device 50, and a complementary longitudinal groove in the outer surface of the insertion needle 40. Such means for alignment could also be provided by the flexible arm for temporarily holding the cutting device 30, 50 at the distal end of the blunt needle 10, 40 initially, said arm thus serving a dual purpose.

The needle hub (not shown) or the proximal end 42 of the insertion needle 40 and the cutting device 50 can advantageously be provided with complementary locking means 16, 23 as described above.

Similar considerations regarding the choice of materials as stated above apply for the parts of the insertions needle 40 and the cutting device 50 as well.

The blunt insertion needle 40 and cutting device 50 are used in a similar manner as described above for the injection needle 10 and cutting device 20, with the exception that when the insertion needle 40 has been fully inserted to the desired depth, the subcutaneous device carried by the blunt insertion needle 40 is delivered in the subcutaneous layer, and the insertion needle and the cutting device 50 are carefully withdrawn, removing the communication means from the track 44 in a radial direction with respect to the longitudinal axis of the insertion needle 40, through the recess 56 in the cutting device.

Alternatively, a transcutaneous sensor having a distal segment adapted for implantation and having a proximal segment adapted for non-implantation can be used with the described cutting device 50 and with the blunt insertion needle 40 providing structural support to the sensor during insertion.

In situations where the distal segment of the transcutaneous sensor is sufficiently rigid to penetrate the tissue in the subcutis, the cutting device 50 can be used without the blunt insertion needle 40 as supporting member. In such a configuration, the blunt needle 10 and 40 as depicted on Figs. 1 , 2 and 5 are substituted with the distal segment of the subcutaneous sensor.

The cutting device 50 adapted for use on an insertion needle 40 could be used in combination with a conventional injection needle 10 as well, the longitudinal recess 56 being redundant in this case.

An additional aspect of the invention is schematically depicted in fig. 7 which shows a sectional view of a cutting device 60 inserted in the skin of a patient. Fig. 7 further shows a transcutaneous sensor 80 ready for insertion. The cutting device 60 is shown in a non-limiting exemplification as a hypodermic needle forming a longitudinal extending tubular conduit which at its tip end 63 is provided with a sharp pointed piercing member 64. The internal part of the conduit forms a channel 62 which is used as a guide for supporting the sensor 80 during insertion of the sensor.

The cutting device 60 is provided with means for limiting the penetration depth of the cutting device so that when the cutting device is inserted into the skin of a patient, the cutting device 60 will only protrude through the epidermis and dermis thereby leaving the hypodermis substantially undisturbed. In fig. 7 the means for limiting the penetration depth of the cutting device is provided as an annular flange 61 either fixedly or adjustably attached to the cutting device 60.

In use, the cutting device 60 is forced against the skin of the user, thereby puncturing the skin with the sharp pointed tip end 63. The cutting device 60 is further advanced through the epidermis and dermis until the stopping surface of the annular flange 61 abuts the surface of the skin. Thus, excessive penetration of the skin by the cutting device 60 is prevented.

Preferably, the cutting device 60 is designed to penetrate the skin with a penetration depth of 0.1 to 8 mm, the penetration depth being defined as the shortest distance from the surface of the skin to the deepest point of penetration of the tip end 63 of the cutting device 60.

An insertion angle is measured from the plane of the skin (i.e., inserting the cutting device 60 perpendicular to the skin would be a 90° insertion angle). Other insertion angles usually range from 10° to 90°, typically from 15° to 60°, and often from 30° to 45°. For applications using insertion angles other than 90°, the cutting device is dimensioned so that the distance from the tip end 63 to the point where the stopping surface intersects the longitudinal axis of the cutting device corresponds to an insertion depth as defined above.

While the means for preventing excessive penetration is shown as an annular flange attached to the cutting member, other forms of penetration limiting mechanisms could be used, as would be readily apparent to one skilled in the art.

The above described cutting device 60 provides an access port in the surface of the skin for insertion of the sensor. In one embodiment, the sensor to be inserted is of the subcutaneous type which is adapted for implantation in subcutis. Alternatively, the sensor is of the transcutaneous type.

One non-limiting example of a sensor type which is suitable for insertion is a transcutaneous electrochemical sensor for sensing analytes of interest, such as blood glucose. In fig. 7, a transcutaneous sensor 80 is shown ready for insertion. The sensor 80 is formed on a flexible substrate and has a narrow distal segment 81 adapted for implantation and a relatively enlarged proximal segment 82 adapted for non-implantation. Sensor electrodes 85 on the tip end 83 of the distal segment 81 are exposed to patient body fluid when the sensor distal segment 81 is placed into the body of the patient. At the opposite end of the sensor contact pads 86 are provided for connection to an appropriate monitoring device (not shown). Preferably, the tip end 83 of the distal segment 81 is rounded or blunt to facilitate insertion of the sensor 80.

According to the embodiment shown in fig. 7, the cutting device 60 is provided along one of its sides with a longitudinal slot 66 extending from the distal end of the cutting device and partly or totally towards the proximal end of the cutting device 30. The slot forms an entry hole for insertion of the distal segment of the sensor into channel 62. Due to the flexibility of the sensor, the sensor is urged further along the channel 62 towards the tip end 63. Pushing the sensor further onwards, the tip end 83 of the sensor 80 clears the distal opening of the cutting device 60 thereby gently parting the subcutaneous tissue. The progression of the sensor is halted when the tip end 83 has reached the desired sensor site. This state is shown in fig. 8. The sensor is typically advanced a further distance of 2 to 12 mm relative to the tip end 63 of the cutting device 60. Other distances usually range from 3 to 8 mm.

In another embodiment, a blunt needle 40 is used during sensor insertion, the blunt needle providing structural support of the distal segment 81 of the sensor during insertion through the cutting device and during further progression through the derma. This configuration is particularly useful in situations where the sensor does not provide sufficient rigidity to be advanced without support. Furthermore, a blunt needle 40 can be used to provide protection against mechanical impacts during insertion. One particular embodiment covers a flexible support needle 40 which is designed to flex in a similar way as the sensor depicted in figs.7 and 8.

The cutting device 60 is optionally pulled out of the skin with distal segment 81 of the sensor 80 remaining in the subcutaneous tissue. In the embodiment shown in figs. 7 and 8, the longitudinal slot 66 facilitates removal of the cutting device, the distal segment of the sensor sliding in the longitudinal slot. For this particular embodiment, a similar slot (not shown) is provided in the stopping flange 61.

In case the cutting device 60 is not provided wit a slot 66 or opening in the sidewall of the cutting member 60, the sensor 80 can be inserted through the opening at the proximal end of the cutting device 60. Such a sensor insertion set comprises a cutting device and a sensor which is provided by a structure showing resemblance to the structure depicted in figs. 1 and 2. In this configuration, the sensor 80 replaces the blunt needle 10, with the optional use of a blunt insertion needle 40 arranged coaxially with the distal segment 81 of the sensor 80, the blunt insertion needle providing structural support during insertion and/or withdrawal of the sensor. Provided that the distal segment 81 of the sensor 80 has sufficient length, the cutting device 60 may still be retracted from the skin during sensor operation.

In the above described embodiments, the longitudinal part of the cutting device 60 is shown as a hypodermic needle. However, any other construction providing the same functional features can be used as the longitudinal part of cutting device 60. Also, the cutting device 20, 50 which has been described in relation to the embodiments incorporating a blunt needle 10 as schematically shown in figs. 1 , 2, 3A, 3B, 4 and 6, can be a part of the sensor insertion set according to the embodiments shown in figs. 7 and 8.

The force applied to the cutting device 20, 50, 60 and/or the sensor 70, 80 and/or blunt support needle 40 during insertion or withdrawal may be applied manually or mechanically. When the forces are applied mechanically, an insertion gun or similar mechanism may be used to force the cutting device 20, 50, 60 and/or the sensor 70, 80 and/or the blunt support needle 40 into the derma.

The combination of a cutting device and a blunt insertion needle or the sensor insertion set as described above may be incorporated in a medical delivery system such as an infusion pump. However, this particular application being non-limiting for the invention disclosed herein.

All references, including publications, patent applications, and patents, cited herein are hereby incorporated by reference in their entirety and to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein (to the maximum extent permitted by law).

All headings and sub-headings are used herein for convenience only and should not be construed as limiting the invention in any way.

The use of any and all examples, or exemplary language (e.g., "such as") provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention. The citation and incorporation of patent documents herein is done for convenience only and does not reflect any view of the validity, patentability, and/or enforceability of such patent documents.

This invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law.

Claims

1. A combination of a cutting device (20, 50) and a blunt needle (10, 40) for insertion through the derma of a patient; said blunt needle (10, 40) having a circumference at the distal end; said cutting device (20, 50) comprising a base part (21 , 51 ) and a cutting member (30) for making an incision in the derma; said base part (21 , 51) having a track (22, 52) adapted for slideable engagement with the blunt needle (10, 40), wherein the cutting member (30) has a cutting width (W) being equal to or less than half the length of the circumference of the blunt needle (10, 40).

2. A cutting device (20, 50) according to claim 1 wherein the cutting member (30) is arched along the circumference of the blunt needle (10, 40).

3. A cutting device (20, 50) according to claim 1 or 2 wherein the arched cutting member (30) covers an angle, α, of 180° or less.

4. A cutting device (20, 50) according to any one of claims 1-3 wherein the arched cutting member (30) covers an angle, α, greater than or equal to 5° and less than 180°.

5. A cutting device (20, 50) according to any one of claims 1-4 wherein the arched cutting member (30) covers an angle, α, of approximately 120°.

6. A cutting device (50) according to any one of claims 1-5 wherein the base part (51 ) further comprises a recess (56) extending from an outer surface (57) to the track (52) of said base part (51).

7. A cutting device (50) according to claim 6 wherein means for securing alignment of the recess (56) in the cutting device (50) and a track (44) in the blunt insertion needle (40) are disposed on the blunt insertion needle (40) and the cutting device (50).

8. A cutting device (50) according to claim 7 wherein said means for securing alignment comprise a tap on the cutting device (50) and a complementary longitudinal groove in the insertion needle (40).

9. A cutting device (20, 50) according to any one of claims 1-8 wherein the cutting member (30) is formed from stainless steel.

10. A cutting device (20, 50) according to any one of claims 1-9 comprising locking means (16) complementary to locking means (23) on the blunt needle (10, 40) for locking the cutting device to the proximal end (12, 42) of the blunt needle.

11. A transcutaneous sensor insertion set, comprising: a sensor (80) having a distal segment (81 ) arranged for implantation and a proximal segment (82) arranged for non-implantation, wherein the distal segment (81 ) is provided with a tip end (83) with at least one sensor electrode (85) thereon, a cutting device (60) having incising means (63, 64) for making an incision in the derma; said cutting device (60) having means (62) for slideable engagement with the distal segment (81 ) of the transcutaneous sensor (80), and wherein said cutting device (60) comprises means (61 ) for limiting the penetration depth of the cutting device (60).

12. The transcutaneous sensor insertion set according to claim 11 , wherein the tip end (83) of the distal segment (81 ) of the transcutaneous sensor (80) is blunt or rounded.

13. The transcutaneous sensor insertion set according to claims 11 or 12, wherein the cutting device (60) comprises a track (62) adapted for slideable engagement with at least the transcutaneous sensor (80) during insertion of the sensor.

14. The transcutaneous sensor insertion set according to any of the claims 11-13, wherein an additional blunt needle (40) supports the distal segment (81 ) of the transcutaneous sensor (80) during insertion.

15. The transcutaneous sensor insertion set according to any of the claims 11-14, wherein the cutting device (60) is configured to a penetration depth of 0.1 to 8 mm.

16. The transcutaneous sensor insertion set according to any of claims 11- 15, wherein the sensor (80) is configured so that its tip end (83) can be advanced 2-10 mm deeper than the penetration depth of the cutting device (60).

17. The transcutaneous sensor insertion set according to any of the claims 11-16, wherein the cutting device (60) defines a longitudinally extending slot

(66) along one side thereof to permit sliding withdrawal of said cutting device (60) from said distal segment (81) of said sensor (80).

18. The transcutaneous sensor insertion set according to any of the claims 11-17, wherein the cutting device (60) is sufficiently short so as to penetrate only the epidermis and dermis without substantial penetration of the subcutaneous layer.

19. A method for inserting of a portion of a transcutaneous sensor into tissue of a subject user, the method comprising: puncturing the surface of the skin of the subject to a predetermined depth with a cutting device (60) having means (63, 64) for making an incision in the derma, said cutting device (60) having a track (62) adapted for slideable engagement with at least a transcutaneous sensor (80), - maintaining the cutting device (60) in place in the skin, inserting the sensor (80) in sliding engagement in said track (62) of the cutting device (60), the distal segment (81) of the sensor (80) having a blunt distal end (83) for penetrating tissue, passing the transcutaneous sensor (80) into the skin substantially beyond the depth of penetration of the cutting member (60).

20. The method according to claim 19, further comprising the step of withdrawing the cutting device (60) from the skin by sliding the cutting device (60) along the distal segment (81 ) of the sensor (80) away from the skin of the subject.

21. The method according to claim 19 or 20, wherein the steps of inserting the sensor (80) in sliding engagement in said track (62) comprises inserting an additional blunt support member (40) for supporting the transcutaneous sensor (80) during insertion.

22. The method according to claim 21 , further comprising the step of withdrawing the additional blunt support member (40) at least partly from the skin by sliding the additional blunt member (40) along the sensor (80) away from the skin of the subject.

23. The method according to any of claims 19-22, wherein said cutting device (60) being sufficiently short so as to penetrate only the epidermis and dermis without substantial penetration of the subcutaneous layer.