Method and device for puncture of insertion needle into subcutaneous fatty tissue

An insertion device with an underside for placing on the skin of a patient, which has a recess for an insertion needle. The insertion device has means for forming a skin surface rising like a step or slope and facing towards the recess, preferably bearing on the recess. The means for forming the step or slope may include first and second pressure areas for pressing the skin with the recess for the needle located between the first and second pressure areas. The device may be configured whereby a downwardly extending cutting plane, in which the insertion needle lies, intersects the first pressure area in a first line and the second pressure area in a second line, and wherein the first line in the vicinity of the recess extends at a greater height than the second line. At least one of the two pressure areas may be a strip.

BACKGROUND

The invention relates to an insertion device. An example of an insertion device is known from WO 2008/136310 A1.

Sensors for in-vivo measurement of analyte concentrations, for example of the glucose concentration, are inserted into subcutaneous fatty tissue of a patient by piercing a needle into the fatty tissue. As a general rule, common insertion needles are designed as hollow needles or V-shaped chutes, with a sensor, for example an electrode system for electrochemical measurements, being positioned therein. After the puncture, the insertion needle is pulled out of the body tissue while the sensor stays in the puncture wound produced.

Usually, insertion devices consist of a basic unit which is placed onto the body of a patient and a lancet device which is coupled to the basic unit for insertion purposes and is, subsequently, removed. There are also insertion devices which consist of only a lancet device.

Insertion systems are often handled by patients themselves in order to insert sensors for the measurement of glucose concentration. For this reason, a constant objective in the development of insertion systems is that they can be handled as easily and safely as possible, anchor sensors reliably in fatty tissue, and allow precise measurements. In addition, the pain connected with the puncture of an insertion needle should be minimized as far as possible.

SUMMARY

The insertion devices disclosed herein provide an improved insertion device.

Whereas conventional insertion devices are simply placed onto the skin of a patient and, subsequently, pierce an insertion needle into subcutaneous fatty tissue at a slanted angle or vertically in relation to the skin surface, the embodiments disclosed herein provide that, prior to triggering a puncture, the puncture site is prepared by deforming the skin and, therein, erecting a skin area such that it is rising in the manner of a step or slope. When a puncture is made, an insertion needle can then impinge on the skin area that is rising in the manner of a step or slope at a steep angle, ideally at an essentially vertical angle, and penetrate into the fatty tissue along a relatively great length before there is the risk of an injury to muscular tissue. Thus the skin surface and the fatty tissue below it are shaped to prepare for an insertion, in order to generate advantageous conditions for a puncture.

In order to prepare a puncture of an insertion needle into subcutaneous fatty tissue, a lower side of the insertion device can, for example, be pressed against the skin, wherein the lower side comprises two pressure areas between which a recess for an exit of the insertion needle is disposed and which are arranged at different heights. This means that a sectional plane which extends from the top down and in which the needle is located intersects the first pressure area in a first line and the second pressure area in a second line. The first line in the neighborhood of the recess then runs at a greater height than the second line. When the insertion device is pressed against the patient, the skin in the neighborhood of the recess and the fatty tissue thereunder are compressed to a greater extent in the second pressure area than in the first pressure area. For this reason, a skin area rising in the manner of a step or slope forms in the vicinity of the recess, with the insertion needle contained in the insertion device pointing to the skin area.

The two pressure areas may be planar. An area in which the recess for the insertion needle is arranged can be provided between the two pressure areas on the lower side of the insertion device, this area, for example, rising in the manner of a step or ramp. It is also possible that the two pressure areas are curved areas which are adjacent to each other at the recess.

A compressing of tissue is advantageous in that the skin can, then, be pierced more easily, but it is not necessarily required. For example, the skin can be bulged by affixing an adhesive area to the skin to be deformed and, subsequently, pulling this adhesive area upwards. It is, however, also possible to cause or support a bulging of the skin by exerting pressure, with the result that tissue is compressed therein. One side of the bulging skin forms a surface that is rising in the manner of a slope and allows an advantageous insertion. This means that the means for forming a skin area rising in the manner of a step or slope can, for example, be designed as means for generating a bulging of the skin.

In some embodiments, at least one of the two pressure areas is a strip. A long narrow pressure area can be pressed into the skin with less force such that there is a step or skin slope forming for a puncture. Preferably, the longitudinal direction of the strip extends in the direction of the insertion needle, i.e. in the piercing direction. Preferably, the width of the strip is less than 1 cm, for example 0.5 cm to 0.7 cm. Preferably, the length of the strip is more than twice its width, more preferably at least four times its width, for example 2 cm to 5 cm.

In general, an insertion needle can more easily pierce through the skin the steeper the angle is at which it impinges on the skin. At the end of an insertion method, a normal to the surface of the skin at the point to which the insertion needle points with its tip, therefore, preferably forms an angle with the insertion needle of less than 30°, more preferably less than 20°, most preferably less than 10°.

In one embodiment of a method according to the invention, the skin surface is, preferably, deformed by the effect of the insertion device at least to such an extent that a normal to the surface at a point of the rising surface to which the insertion needle points includes an angle with a normal to the surface at the same point of the skin surface prior to deforming of at least 45°, preferably of at least 60°.

Preferably, the insertion needle is held in the insertion device in a direction that extends obliquely from the top down, which means that it extends at a slanted angle in relation to the lower side of the insertion device. Herein, the terms “down” and “top” refer to the insertion device, wherein the lower side of the insertion device is the side that is seated on the skin of the patient during a puncture or after completion of the insertion method. Accordingly, the upper side of the insertion device is the side that is facing away from the skin of the patient during a puncture or after completion of the insertion method.

An insertion device according to the invention has means for forming a skin area rising in the manner of a step or slope which faces the recess provided for the exit of the insertion needle. This means that the insertion device forms the skin such that a skin area is erected in the manner of a step or slope and is then facing the recess, for example an outlet opening. Preferably, the skin is formed by an exemplary insertion device such that the skin area rising in the manner of a step or slope rests against the recess because, in this manner, the puncture site is defined particularly well.

The means for forming a skin area rising in the manner of a step or slope can, for example, be means for maintaining a bulging of the skin of the patient. An insertion needle contained in the insertion device is, preferably, oriented at a slanted angle in relation to a resting or pressure area of the insertion device, next to which the bulging is generated. This means that the insertion needle points in a direction which includes an acute angle with a planar resting or pressure area, this angle, for example, ranging from 2° to 45°, more particularly from 20° to 45°. Since, usually, insertion needles extend in a straight direction, the insertion needle then includes an acute angle with the resting area as well. As such, the resting or pressure area can also be somewhat rounded, for example adjusted to the natural curvature of a belly. In such a case, the slanted orientation of the insertion needle means that a tangential extension of the area intersects the direction into which the insertion needle points at an acute angle.

The means used for forming the skin can, for example, be two holding parts which are movable against each other and between which a bulging of the skin is seized.

If two holding parts that are movable against each other are used to generate and hold a bulging of the skin, these holding parts preferably each comprise a pressure area for the bulging of the skin. Preferably, the insertion needle points along at least one of the pressure areas, being spaced apart therefrom. During a puncture, the insertion device then pushes the insertion needle along the pressure area spaced apart therefrom, preferably in a direction extending essentially parallel to the pressure area. The insertion needle can, thus, be pushed into subcutaneous fatty tissue in parallel to the skin surface.

It is possible that the pressure area of the other holding part comprises a recess, e.g. an opening for the insertion needle. It is, however, also possible that the insertion needle points through between the two pressure areas, i.e. that, during a puncture, the insertion needle is moved past the two pressure areas spaced apart therefrom.

An advantageous refinement of the invention provides that the insertion device is composed of a first and a second partial body wherein the first and second partial bodies are movable against each other and a slit extends between the first and second partial bodies and through the recess provided for the exit of the insertion needle. By the two partial bodies being movable against each other, the slit extending through the recess can be enlarged after a puncture, so that the insertion device can be removed from the patient more easily, for example in order to facilitate the handling of a sensor patch connected to the sensor. Sensors are often connected to what is called a sensor patch which is adhered to the skin of the patient after the insertion of a sensor. A sensor patch can, for example, contain a potentiostat for supplying an electrode system forming the sensor with energy, a battery and/or control electronics.

Preferably, the two partial bodies can be removed from each other. However, the slit extending between said partial bodies can, for example, also be broadened by a swivel movement of the two partial bodies against each other to such an extent that a sensor patch that is connected to the inserted sensor can be placed on the skin of the patient.

DETAILED DESCRIPTION

FIG. 1shows a skin surface1with an inserted sensor2. A skin area1ais rising in the manner of a step or slope having been generated in the skin surface1by deformation. The sensor2projects from the skin area1arising in the manner of a step or slope and extends in the subcutaneous fatty tissue in essence in parallel to the skin area1bwhich is disposed thereupon and, at its top, is adjacent to the skin area1arising in the manner of a step or slope at the top.

A step- or slope-like rise is only preserved as long as a corresponding force acts on the skin surface1and accordingly deforms the skin surface1with the fatty tissue disposed thereunder. Once such a force is not in effect any longer, for example because the insertion device causing the deformation has been removed from the skin surface1, the skin surface1relaxes and returns into its natural state that is approximately flat and whereby a sensor inserted in the subcutaneous fatty tissue is bent as shown inFIG. 2. The section of the sensor previously extending in parallel to the skin area1bis oriented approximately in parallel to the skin surface1even with the skin surface1being relaxed and can, therefore, extend along an advantageously great length in fatty tissue under the skin.

This means that, in order to prepare a puncture of an insertion needle into subcutaneous fatty tissue of a patient by means of an insertion device, the skin is deformed by an effect of the insertion device and a skin area is arranged such that it is rising in the manner of a step or slope and an insertion needle held in the insertion device points to the skin area1arising in the manner of a step or slope.

A normal to the surface of the skin area1in the point to which the insertion needle points defines an angle with a theoretical prolongation of the insertion needle of, for example, less than 30°, ideally an angle of 0°. The insertion needle is therefore oriented at a slanted angle in relation to the skin surface1b,1cnext to the skin area1arising in the manner of a step or slope. This means that, in relation to normals to the skin surface1b,1cnext to the bulging of the skin, the insertion needle defines a larger angle, for example an angle ranging from 30° to 60°.

In order to prepare an insertion of a sensor by means of an insertion device, a skin area1arising in the manner of a step or slope can be generated in various ways. Below, a few illustrative embodiments of insertion devices will be explained, which can be used to generate a skin area1arising in the manner of a step or slope and maintain it for the duration of an insertion process.

FIG. 3shows an illustrative embodiment of an insertion device3in its initial state, in which the device3is placed onto the skin of a patient. The insertion device3has two holding parts3a,3bwhich are movable against each other in order to generate a bulging of the skin with a skin area rising in the manner of a slope and maintain it subsequently. The two holding parts3a,3beach have a pressure area4aand4b, respectively, with which the insertion device3is pressed against the skin of a patient in order to prepare an insertion. An adhesive film5is fastened to the two holding parts3a,3b. The adhesive film4therefore bridges a groove between the two holding parts3a,3b. In the illustrative embodiment shown, the holding parts3a,3bare movable against each other by being pushed and, to achieve this, connected to each other via a linear guide6, for example one or a plurality of guiding rods.

In order to generate a bulging of the skin, the two holding parts3a,3bare pushed together into the final state shown inFIGS. 4 and 5. Therein, the adhesive film5and, therefore, the skin adhered to it as well, are bulged up, with the result that the adhesive film5rests against the resting areas7a,7bof the holding parts3a,3band a bulging9of the skin is seized by the partial bodies3a,3b. The sides of the bulging9of the skin are skin areas rising in the manner of a slope.

In the illustrative embodiment shown, the holding part3bsupports the insertion needle8. A part of the insertion device that contains the insertion needle8can be permanently connected to the first holding part3aor be applied to the first holding part3aonly for the actual insertion process, i.e., the puncture.

In the illustrative embodiment shown, the resting area7bof the holding part3bhas a recess, that is an opening for the insertion needle8shown inFIG. 5. When a puncture is made, the insertion needle8impinges on a lateral surface of the bulging9of the skin, preferably almost vertically, and then moves under a flat angle, preferably in parallel, to an opposite lateral surface of the bulging9of the skin which rests against the resting area7aof the holding part3a. In the illustrative embodiment shown, the insertion needle8is, in essence, slid into subcutaneous fatty tissue in parallel to the resting area7aof the holding part3b.

In an insertion device3which consists of two holding parts3a,3bthat can be pushed against each other, as is the case in the illustrative embodiment shown, the resting area7bof the holding part3bsupporting the insertion needle8, preferably, has a smaller length than the resting area7aof the other holding part3a. Therein, the length of the resting areas7a,7bis each to be measured from the neighboring pressure area4aand4b, respectively, in the direction towards the other holding part. Preferably, the longer resting area7ais at least twice as long as the shorter resting area7b.

Preferably, the pressure areas4a,4bof the two holding parts3a,3bare, in essence, planar and oriented in parallel to each other. In the illustrative embodiment shown, the resting areas7a,7bfor forming and holding a bulging of the skin are, in essence, planar, too, but can also be curved. Starting from the pressure areas4a,4b, the resting areas7a,7brise upwards, with the result that they limit a recess on the lower side of the insertion device3, which can receive a bulging of the skin. The pressure areas4a,4bare each formed as straight-line strips.

When the insertion device3is placed onto the skin surface1of a patient, the insertion needle8initially points at a slanted angle to a point of the not yet bulging skin surface. This means that, in this point of the skin surface1, a theoretical prolongation of the insertion needle8in the direction of the puncture defines a first angle with a normal to the surface of, for example, 30° to 60°. After the bulging of the skin has been generated, the insertion needle8points to a lateral side of the bulging of the skin, i.e. to the skin area rising in the manner of a slope. A normal to the surface of the skin area in the point to which the insertion needle8points then defines a second angle with a theoretical prolongation of the insertion needle8in the direction of the puncture, this second angle being smaller than the first angle and, preferably, less than 30°, more preferably less than 20°. In an ideal situation, the insertion needle8points vertically to the skin area rising in the manner of a slope.

FIG. 6schematically shows a further illustrative embodiment of an insertion device3in its initial state in which the insertion device3can be placed onto the body of a patient. In essence, the illustrative embodiment shown inFIG. 6differs from the embodiment described above only in that the two pressure areas4a,4bare arranged at different heights and offset in relation to each other. For this reason, a theoretical prolongation of the pressure area4aof the holding part3aintersects the resting area7bof the holding part3bwhich comprises the opening11for the insertion needle8.

When the insertion device3is pressed onto the skin of a patient, the tissue in the vicinity of the skin area rising in the manner of a slope is compressed to a greater extent by the offset arrangement of the two pressure areas4a,4b. This is advantageous in that the tissue can give way to a lesser extent and a sensor2can be placed more precisely in the subcutaneous fatty tissue during the puncture of the insertion needle8.

A further illustrative embodiment of an insertion device3is shown inFIG. 8in its initial state for being placed onto the skin of a patient and inFIG. 9in its final state that is provided for holding a bulging9of the skin. In essence, this illustrative embodiment differs from the embodiment ofFIGS. 3 to 5in that the two holding parts3a,3bare movable against each other in a swiveling manner. At first, the insertion device3is placed onto the skin of a patient with the two resting areas7a,7b. The two resting areas7a,7bare adhesive areas, for example by the holding parts3a,3bbeing covered with an adhesive film5at this point. Thereafter, the holding part3ais swiveled against the other holding part3b, with the result that the holding parts each press against the skin of the patient with their pressure areas4. The skin adhered to the resting areas7a,7bis pulled upwards and, therefore, a bulging9of the skin is generated and held between the two holding parts3a,3b. The bulging9of the skin forms a skin area that rises in the manner of a slope and rests against an opening11for the insertion needle, the opening11being present in the resting area7a.

The two holding parts3a,3bcan be connected to each other via a film hinge10which can, for example, be formed by the adhesive film covering the resting areas7a,7b.

FIG. 10shows a detail of the insertion device3shown inFIG. 9, with a protruding insertion needle8. As is evident, the orientation of the insertion needle8with respect to the pressure areas4and the resting areas7a,7bdoes not differ from the geometrical conditions of the embodiment shown inFIG. 5.

FIGS. 11 and 12show a further illustrative embodiment of an insertion device3with a skin surface1. At first, the insertion device3is placed onto the skin with the resting area7awhich is formed as an adhesive area and comprises an opening for the insertion needle. Thereafter, the insertion device3is tilted over from the initial position shown inFIG. 10to the final position shown inFIG. 11, with the result that a pressure area4of the insertion device3is pressed against the skin1. In the embodiment shown inFIG. 11, the pressure area4defines an obtuse angle with the resting area7a. Since the skin1adheres to the resting area7a, the tilting of the insertion device to the final position shown inFIG. 12generates a bulging9of the skin, into which a puncture with an insertion needle8can be made thereafter.

FIG. 13shows a further illustrative embodiment of an insertion device3in which the means for generating and holding a bulging9of the skin comprise holding parts3a,3b,3cthat are movable against each other. The holding parts3band3care attached to the holding part3ain a swiveling manner. In the initial state shown inFIG. 13, the insertion device3is placed onto the skin of a patient. Thereafter, the holding part3ais tilted similarly to the embodiments described above. The two holding parts3band3care swiveled to the final state shown inFIG. 14. The holding part3bcomprises the resting area4with which the insertion device3is pressed against the skin. The holding part3aforms a resting area7afor the bulging9of the skin and comprises an opening for the insertion needle. The holding part3cforms a resting area7bwhich rests on the other side of the bulging9of the skin.

A further illustrative embodiment of an insertion device3is shown inFIG. 15in its initial state in which it is placed onto the skin of a patient and inFIG. 16in its final state that is provided for holding a bulging9of the skin. This embodiment also comprises two holding parts3a,3bthat are movable against each other as means for generating and holding a bulging9of the skin. At first, the device is placed onto the skin of a patient with the resting area7bof the second holding part3b. The resting area7bis formed as an adhesive area, for example by means of an adhesive film5. Thereafter, the holding part3ais swiveled in relation to the holding part3b, with the result that the holding part is pressed against the skin of the patient with its pressure area4. Therein, the holding part3ais moved upwards and the holding part3ais pressed down, respectively, with the result that a difference in height and, therefore, a skin area rising in the manner of a slope develops between the resting area7bof the holding part3band the pressure area4of the holding part3a.

In the final position shown inFIG. 16, the tip of an insertion needle points through the opening11in the resting area7aof the one holding part3aand along the resting area7bof the other holding part3bbeing spaced apart therefrom. To trigger a puncture, the insertion needle is slid into subcutaneous fatty tissue in parallel to and along the skin surface resting against the resting area7bof the second holding part3b.

FIG. 17shows a further illustrative embodiment of an insertion device3in which the means for holding and generating a bulging9of the skin are formed by two holding parts3a,3bof the insertion device3that are movable against each other. In the embodiment shown inFIG. 17, the two holding parts are movable against each other in the manner of a clamp and each have a resting area4with which the holding parts can be pressed against the skin of a patient. After having been placed onto the skin of a patient, the two holding parts swivel from an initial position to a final position, preferably under the influence of the restoring force of a spring, with the two resting areas4having been moved closer to each other and, therefore, having bulged the skin between them in this final state. A generated bulging of the skin then rests against the resting areas7aand7b, respectively, of the two holding parts3a,3b. In its final position, the insertion needle8points along the resting areas7a,7bof the two holding parts3a,3bspaced apart therefrom, preferably in parallel to and along the resting areas7a,7b.

A further illustrative embodiment of an insertion needle is shown inFIG. 18. In this embodiment, the skin is deformed by pressing the lower side of the insertion device against the skin. The lower side comprises a first pressure area4aand a second pressure area4b, wherein a recess, preferable an opening, for the insertion needle8is located between the two pressure areas4a,4b. The pressure areas4a,4bthat are formed as strips are arranged at different heights, similarly to the embodiment ofFIGS. 6 and 7. This means that a sectional plane which extends from the top down and in which the insertion needle8is positioned intersects the first pressure area4ain a first line and the second pressure area4bin a second line and the first line in the neighborhood of the recess extends at a greater height than the second line. Since the aforementioned sectional plane contains the needle8, the sectional plane also extends through the recess, with the result that there are two lines separated by the recess.

The two pressure areas4a,4bcan continuously merge in an area rising in the manner of a ramp, in which the recess for the insertion needle8is arranged, or can be separated from each other in a defined manner.

When the lower side of the insertion device is pressed against the skin, the subcutaneous fatty tissue is compressed by the pressure areas4a,4b. The tissue is compressed by the pressure area4bthat is positioned at a lower height to a greater extent than by the pressure area that is positioned at a greater height, with the result that the skin between the two pressure areas forms an area which rises in the manner of a slope and rests against the outlet opening.

In the embodiment shown, the first pressure area4aextends further than the insertion needle8in the state which is shown inFIG. 19and is reached at the end of the feed motion when a puncture is made. For this reason, the insertion needle8is always covered by the insertion device along its entire length.

The first pressure area4ais a straight-line strip. Preferably, this strip has a width of less than 1 cm, more preferably of less than 6 mm. In this manner, the pressing force is concentrated on an advantageously small area, with the result that a compression of tissue can be achieved while exerting little force, for example a force of less than 30 N, preferably of less than 20 N, more preferably of 10 N to 20 N. In the embodiment shown, the pressure area4bis also a straight-line strip having a width of less than 1 cm, for example 0.5 cm to 0.7 cm. When being pressed on, the insertion device, therefore, acts on the skin of a patient in a strip-shaped area. Preferably, the length of this strip-shaped area is at least 2 cm, for example 2.5 cm to 5 cm.

The second pressure area4bis arranged between two supporting areas which extend both laterally away from the pressure area4band upwardly. This means that the insertion device becomes broader in an upward direction, starting at its lower side. When the insertion device is pressed on, the lateral supporting areas14act as spacers for displaced tissue, with the result that an increased working space for a piercing mechanism is created.

In the embodiment shown, the piercing mechanism is designed as a slide15which, during a puncture, is pushed forward along with the insertion needle8it holds. The slide15is guided along a linear guide6which can, for example, be formed by guiding rods. During a puncture, the slide15can move a holder20of the sensor patch16.

After a puncture, the slide15is, initially, removed from the insertion device.FIG. 20shows the insertion device after the slide15has been removed.

The insertion device comprises two partial bodies17a,17b. A seam18extends through the opening between the first partial body17aand the second partial body17b. The seam18extends in the longitudinal direction of the device, that is through the two pressure areas4a,4b. In principle, however, the seam18can also extend in transverse direction in relation to the insertion device.

The two partial bodies17a,17bare movable against each other in order that the insertion device can be removed from the body of a patient more easily after the puncture of the insertion needle8. In the embodiment shown, the first and second partial bodies17a,17bare held together by magnetic force. The magnetic force can be overcome manually, with the result that the two partial bodies17a,17bcan be detached from each other if necessary.FIG. 21shows the first partial body17aof the device after the second partial body17bhas been removed. In a further step, the first partial body17ais removed as well. And thereafter, the sensor patch16is adhered to the skin.

In order to connect the two partial bodies17a,17bto each other by magnetic force, the two partial bodies17a,17bcan carry one or a plurality of permanent magnets19. As such, however, it is sufficient to provide only one of the two partial bodies with a permanent magnet. The other partial body can also carry a soft magnet instead of a permanent magnet, for example by consisting of ferromagnetic steel at the corresponding point.

In order to facilitate manually overcoming the magnetic force for separating the two partial bodies17a,17b, one of the two partial bodies17bcan project a little beyond the other partial body17aon the upper side. In this manner, an area of attack can be formed, for example in order to exert the force required for overcoming the magnetic attraction with one's thumb. It is, however, also possible that the seam18between the two partial bodies17a,17bbroadens in an upward direction in the manner of a wedge or funnel at one point or at a plurality of points. In this manner, it is possible to reach into the seam with one of one's fingers in order to press the two partial bodies17a,17bapart.

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