HK1058468B - System for removing body fluid - Google Patents

Description

System for extracting body fluid

Technical Field

The present invention relates to a system for extracting body fluid from a body part, in particular from the belly of a finger. The body fluid is drawn primarily for subsequent analysis for use in diagnosing disease or monitoring the metabolism of a patient. Such blood drawing is performed, in particular, for diabetics, to determine blood glucose concentrations. The purpose of such a daily blood glucose test is to avoid hypoglycemia as well as hyperglycemia. Hypoglycemia can cause a patient to fall into a coma and even die because it does not provide sufficient glucose to the brain. Conversely, hyperglycemia can lead to a variety of side effects, such as blindness, gangrene, and the like.

Background

Therefore, it is needless to say that the blood glucose level is frequently measured. Thus, there is clearly a great need for a system which can be easily operated by the user, most importantly pain-relief.

Blood drawing systems have long been known in the art and are used by patients and medical personnel to draw blood conveniently. An example of a commodity of practical use at hand is Softclix, the way it works being described in US5,318,584. This device provides a means for adjusting the depth of insertion of the lancet into the tissue. The patient can thus select the minimum puncture depth, obtain a blood volume just enough for analysis, and reduce the puncture pain. After puncturing the patient's skin, particularly at very small penetration depths, the patient's finger must be massaged and pressed in order to extract a sufficient amount of blood from the punctured wound. This method, often referred to as "melken" by diabetic patients, has hitherto only been avoided when too deep a laceration is unpleasant for the patient and severe scarring occurs on the painful finger belly. In the prior art, attempts have been made to use a known device for increasing the amount of blood drawn by means of a vacuum, however with little effect.

In another device known from the prior art, a so-called stinger, which is pressed against the skin surface with a ring, surrounds the puncture site. Such a device for obtaining interstitial body fluid is described, for example, in US5,582,184. The ring used to press against the skin surface is made of a rigid material. Only small amounts of liquid are available with this device and are not readily available in commercially available analytical systems.

US5,857,983 discloses another device in which an injection cannula is inserted into the skin surface and the stimulator is used to press the skin surface around the puncture site in response to pressure to force fluid pressure into the injection cannula. In this device a rigid ring similar to that described in the above document is used to press against the skin surface. Also, the amount of body fluid obtained with this device is not sufficient for use with commercially available analytical systems.

In US5,951,493 there is also described a blood drawing device which also uses a stimulator as described in the above mentioned US patent. In addition, in fig. 15 to 17, a device is described, which is equipped with a lever (104) in the area where the body surface is pressed, which lever presses a skin site in the lateral direction when the device is pressed against the skin surface. The device described in this patent is particularly useful for extracting body fluid from locations other than the fingers. Furthermore, the literature shows that the delivery of body fluids to the skin surface is achieved by a repetitive compression device.

Document US 3,626,929 discloses a device for clamping the fingers between a rod and a finger rest before drawing blood. The finger rest is pushed by a motor to massage the vicinity of the puncturing device. To take a sample, the user's finger is pressed against a flexible cap in which the needle and the tube are placed. The disadvantage of this device is that the needle remains in the body for sampling purposes, in which case the finger holder is pushed. This causes the needle to move in the finger, causing great pain. Furthermore, there is a high probability that blood will not flow out because the needle in the finger blocks the passage when the needle is in the finger. In fig. 11 and 12, a collection container is shown which has a flexible pressure application region. Based on the shape of the pressing area expanding towards the finger taper, the initial pressing action is not translated into a lateral one, pressing against the movement of the extraction area.

Disclosure of Invention

The object of the present invention is to provide a system for extracting body fluid which provides sufficient body fluid, in particular blood, for shallow penetration. In addition, the invention also aims to provide a system which is easy to operate and has a simple structure. The simple meaning is to specify that the number of operating steps is as small as possible.

It is a further object of the present invention to facilitate the extraction of a blood sample from the finger belly, taking into account the size of the finger and the different positions of the perforations in the finger.

The invention thus relates to a system for extracting body fluid from a part of the body, in particular from the belly of a finger, having the following structure:

a compression unit, against which the body part is pressed in an initial direction, a part of the pressure exerted by the compression unit being converted into a movement in a second direction, which has a component perpendicular to the initial direction, compressing the unit, thereby increasing the internal pressure inside the body region,

a puncturing device, in particular a lancet or an injection cannula, for puncturing an opening in a body region with an increased internal pressure, wherein the compression unit has a pressure application zone made of a deformable material.

The pressing area has an inner width of 4mm or more of the opening before pressing.

In addition, the invention also relates to a system for stimulating the liquid of the human body to flow out of the human body part, a method for stimulating the liquid of the human body to flow out and a method for extracting the body fluid.

With the compression unit according to the invention, the user can comfortably and simply imitate the milking action described above by expressing the blood sample from the puncture site. The compression unit not only provides a greater volume of body fluid than the prior art compression devices, but the patient feels a significant comfort in the compression and extraction process. This is due to the fact that the compression unit fits comfortably against parts of the human body, in particular the fingers. An additional factor is that the compression unit can obtain a sufficient amount of body fluid with a small penetration depth.

Furthermore, the invention has the important advantage that by using a compression unit with a pressure application region made of a deformable material, it is possible to reliably and comfortably extract body fluids from body parts of various shapes by means of the compression unit. In particular, the finger can be easily and reliably extracted from various fingers with different sizes. In addition, deformable materials are used to accommodate the various shapes of the body part being pressed (finger side and fingertip).

The use of the system of the present invention is particularly advantageous for drawing capillary blood from the belly of a finger. In addition, blood or interstitial fluid may be drawn from other body parts, for example, from the arms.

The most important part of the system is the compression unit which causes the body part not only to form a compression in the direction of the initial pressure application, but also at least a partial pressure deflection such that said pressure generates a force component in a direction perpendicular to the direction of the initial pressure. Whereby the region to be extracted at the body part is laterally compressed. The effect of this advantageous compression will be explained in more detail below with reference to an embodiment. The internal pressure in a region of the body part is increased by the compression unit. The region in which the internal pressure is increased is adjacent to the region to be pressurized or is surrounded by the region to be pressurized. Now the puncturing device can be used to puncture the area with increased internal pressure to extract the body fluid.

The compression unit comprises a compression area consisting of a deformable material. This material is on the one hand more comfortable for the user during the extraction process and on the other hand can easily be adapted to body parts of various shapes and sizes. A deformable composite material such as an elastomer, rubber, or the like may be used as the crush-zone deformable material. The extruded region is preferably formed in the shape of a ring. This is technically clearly different from the arrangement described in figures 15 to 16 of US5,951,493. In prior art devices, the structural arrangement employs separate lever arms that laterally compress the body surface. This has a number of disadvantages. Due to the distance of the lever arms, there is an untouched place of the skin between the lever arms. The lateral pressure on the skin surface is not perfect and even worst, the skin may be forced between the lever arms when the separate lever arms move towards each other. Finally, it should also be noted that the prior art devices are neither considered nor suitable for use on a variety of different sizes or different human body surfaces. This device is primarily concerned with extracting body fluid from an arm that has a relatively small degree of curvature relative to the finger pad. The above-mentioned problems are avoided by using a, preferably annular, pressing area made of a deformable material.

The system for drawing body fluid also has a puncturing device for puncturing the body. Such a lancing device is used to lance a lancet or an injection cannula.

In the case of a lancet, it is preferred that the lancet is completely removed from the tissue after the puncture, so that body fluid is easily expelled from the puncture. In the case of an injection cannula, it may be stopped at the deepest penetration depth to withdraw body fluid from this depth or it may be withdrawn to the skin surface from where it is withdrawn. It is also possible to partially withdraw the injection cannula, a part of the fixed puncture channel being open, the injection cannula remaining in the skin. Hereby, on the one hand, flushing of liquid through the open puncture channel can be improved and, on the other hand, it is no longer necessary to place the infusion cannula on the surface of the body.

The puncturing device can preferably enter the body surface through an opening in the compression unit or in the compression area. To obtain different penetration depths, to accommodate different skin types and to obtain the desired blood volume, it is advantageous to have varying penetration depths. In order to obtain a defined (and possibly previously adjusted) penetration depth, the movable arrangement of the puncturing device relative to the compression unit is particularly advantageous. The movability of the device comprises two interrelated aspects, a first aspect in which the puncturing device is spring-loaded relative to the compression unit such that the front side or contact block of the puncturing device is resiliently applied to the surface of the body when the compression unit is pressed against the body part. The pressure exerted by the puncturing device on the surface of the human body is advantageously in the range of 1 to 5N, preferably about 2N. The use of a greater force risks the discharge of body fluid in the lower area.

In a second aspect, the mutual movability of the puncturing device and the compression unit involves the movement of the puncturing device to and from a puncturing position in order to make room for the withdrawal means to perform a withdrawal of body fluid. This aspect is particularly important for an integrated arrangement in which not only the blood sample is drawn but also the analysis is performed.

In a preferred embodiment of the invention, the analysis system is integrated in a system for extracting a body fluid. Such analytical systems have long been known in the prior art. For example, commercial analytical systems are available under the names Accucheck Plus and Accucheck Advantage. Analytical systems typically designed for consumers use disposable test elements that, upon contact with the fluid under test, produce a signal related to the concentration of the analyte. In the field of blood glucose measurement, not only optical test elements are used, which cause a color change by the reaction of glucose with a test chemical, but also electrochemical test elements, which make it possible to measure the analysis of the current and the potential by enzymatic conversion of glucose. It is advantageous to design the test element in a configuration that stimulates the withdrawal of body fluid (e.g. by means of a capillary gap).

According to the system of the invention, the extraction unit is simply integrated with an analysis system, or such integration is effected for the first time. As mentioned above, the prior art typically expresses bodily fluids by manual pressure after lancing the skin at the outlet, which means that the patient must remove the body part from the extraction device. With the system of the present invention, the patient can press a body part against the deformable compression unit, where it remains pressed, completing the puncture and extraction on the skin. The degree of automation is high, the patient only needs to press the compression unit, and all subsequent steps are automatically carried out until an analysis result is given.

The integration of the puncturing device and the analysis system involves the advantage not only of spatial integration but also of a set of processes, which can eliminate manual steps for the user. The system is also advantageous in that it has a control unit which simultaneously controls the excitation and withdrawal means, the withdrawal of body fluid and the delivery of body fluid to the analysis system for analysis.

Drawings

An embodiment of the system according to the invention is explained in detail below with reference to the figures:

FIG. 1 is a perspective view and a cross-sectional view of a compression unit;

FIG. 2 is a perspective view and a sectional view of a fingertip pressing region;

FIG. 3 is a stroke-pressure diagram of a finger pressing on the compression unit according to FIG. 1;

FIG. 4 is a cross-sectional view of another embodiment of a compression unit;

FIG. 5 is an integrated system for analyzing body fluid using the compression unit of FIG. 1;

fig. 6 is an integrated system for analyzing body fluids, comprising a compression unit, a puncture device and an analysis unit.

Detailed Description

Fig. 1 shows a first embodiment of a deformable compression unit. In the perspective view shown in fig. 1A, the compression unit 10 is mounted on a plate 20. As can be seen from the cross-sectional view of fig. 1B, the compression unit is provided with two tapered regions 10a, 10B as regions to which pressure is applied for extraction. The upper part 10a of the pressure-applying region tapers in the direction of the plate 20 and then in the lower region 10b tapers in the direction of the plate. The compression unit is made of a deformable plastic, in the example described polyurethane. Polysiloxanes and rubbers may also be used. It is important that the compression unit is capable of deforming under very light compression forces, while at the same time being sufficiently rigid to be able to generate the necessary resilience and sufficient transverse compression forces. The material suitably has a hardness of less than 90 shore, preferably less than 50 shore, most preferably 20 to 40 shore.

By means of two opposite arrow configurations in cross-section, and by means of deformability, the initial movement of the body part perpendicular to the plate 20 is at least partially converted into a lateral movement. Whereby the corresponding secondary movement stresses the body part, i.e. the manual milking action normally performed by the user.

With a 30 Shore hardness compression unit as shown in FIG. 1, many patients have reached a puncture depth of 0.7mm and obtained a blood volume of 1.5-3. mu.l from the finger belly. The amount of blood obtained is substantially determined by the volume of tissue compressed with the compression unit, and for this reason the amount of blood is limited, thereby avoiding the hygienic problem of excessive blood volume.

The invention also encompasses configurations in which the initial motion of the body part relative to the compression unit is at least partially translated into a perpendicular motion. Therefore, in a secondary example, a system is also included in which the upper region 10a of the compression unit is missing and the conversion of the initial action into the secondary action is done only by the lower part 10 b. The concept of deformable is not only embodied in such a deformable material as in the embodiment shown in fig. 1, but also in embodiments in which its geometry is deformed or changed by an initial action. An example of such an embodiment is described below in conjunction with fig. 4.

Fig. 2 shows the operation and action of the compression unit of fig. 1. As can be seen from fig. 2A, the user presses on the compression unit with a part of the body, preferably a fingertip, causing the compression unit to depress, the inner width 12 of the compression unit becoming smaller. The fingertip area is thereby compressed and the internal pressure in this area 50 increases. The inner width 12 is in the ideal range of 8 to 11mm, which is suitable not only for adults but also for the fingers of small children.

As can also be seen from fig. 2b, in this embodiment the compression areas 10a, 10b are not only twice displaced parallel to the plate 20, but also arched downwards. This deformation behavior of the compression unit enhances the pressure effect in the body-gripping region, which is beneficial for increasing the internal pressure. A particular advantage of the deformable material having a depressed area in the compression unit shown in fig. 1 is that it is adapted to the structure of the human body part. It also may draw a blood sample from the side of the fingertip, something that rigid pressure applying devices cannot do.

By suitably selecting the thickness and hardness of the material, the user should feel the impression that the compression unit is partially overlapped when pressing down the compression unit. Whereby the user can feel whether the pressure of the drawn blood sample is sufficient. However, the basic principle of the operation of the compression unit according to the invention still remains a structure in which such an overlap is not effectively perceived.

As can be seen from fig. 2, in the connecting region 14 between the compression unit 10 and the plate 20, large tensile stresses occur under pressure. It follows that tensile stress is very beneficial for the function of the structure. This has the advantage of ensuring a dynamic coupling between the compression unit and the plate, in particular the connection of the two components to each other in the region 14.

The other details, which can be seen from fig. 2, are the meaning of the thickness d of the depressed area. In the case of a depression, the upper depression area and the lower depression area overlap each other, resulting in the body part exerting a greater pressure on the compression unit.

The folding effect of the compression unit described above can be seen in fig. 3. The abscissa represents the path length mm of the fingertip relative to the compression unit. The ordinate is the repulsive force between the finger and the compression unit. As can be seen from fig. 3, the repulsive force increases when the finger starts to be depressed, and decreases again after passing a maximum value. The corresponding position in the state shown in fig. 2 (maximum) is 5 mm. Beyond the maximum force the user feels a folding sensation, while at the same time the user is warned that the force with which his fingers press on the compression unit is sufficient. Overriding the maximum force is advantageous because it encourages the user to continue to press the finger against the compression unit, completing the puncture and drawing blood.

Fig. 4 shows an embodiment similar to that of fig. 1 and 2, however, the compression unit is formed by rigid elements which are bent under the pressure of the body part, so that the overall geometry of the compression unit is deformed. The compression unit of fig. 4 has a number of lamellae 11, which are each at a distance from one another and which have a bevel 21 on their outer side, when the foil unit is pressed to slide into a tension ring 22. By means of this bevel they move together in the depressed area and the foil 11 is covered by a cover 23 made of an elastic material. In this embodiment, the initial pressure action of the finger also produces a secondary motion perpendicular to the direction of the initial pressure, which results in pressure against the side of the skin surface. As can be seen in fig. 4b, a high internal pressure 50 is generated in the body region. The cover 23 of elastic material has the function of, on the one hand, keeping the skin from getting caught between the lamellae and, on the other hand, adapting the compression unit to the geometry of the depressed body part.

Fig. 5 shows an integrated system for analyzing a body fluid, comprising a compression unit as shown in fig. 1. As described above, the compressing unit has an opening on which a portion of the human body is pressed. The puncture device can touch the human body part through the opening in the compression unit, not only can puncture a small hole on the skin, but also can extract body fluid through the small hole. In the embodiment shown in fig. 5, the perforation means comprises a needle 60 which is inserted into the pressure application zone and stays there for collecting body fluid. The needle 60 is connected to an analysis area 62 which changes the colour of the sample shown depending on the concentration of the analysis. For analysis, the analysis region 62 is illuminated by a light source L, and a detector D detects the reflected light beam. The light source L is controlled by a control unit 71, and the signal of the detector is analyzed by an analyzing unit 72. The analysis unit 72 preferably also controls the unit 71. The analysis unit 72 analyzes the signal of the detector in order to determine the concentration of the analyte contained in the body fluid. The analysis result is output via an output unit 73, which is, for example, an LC display.

Fig. 6 shows an integrated system with which skin is perforated and subsequently blood samples are automatically analyzed. The system comprises three functional units: a compression unit 10, a puncturing device 80, and an analysis system 90, which are movably mounted on a linear guide unit 100, respectively. The linear guide unit 100 consists of a guide rail to which three movable saddle frames 101, 102, 103 are fixed. The first saddle 101 is moved by means of a gear 104 and a rack 105 by means of a servo drive (not shown in the selected view). The movement of the first saddle 101 is transmitted to the second saddle 102 by means of a spring 106 and carries the puncturing device 80 fixed thereto. The pressure of the puncturing device on the finger can be kept constant all the time during the travel due to the action of the spring. This force should not exceed 2N. There is a risk that blood that has collected on the fingertip will be squeezed out of the sealed volume during compression and puncture. Thereby potentially reducing the amount of blood collected. The drive button 81 of a puncturing device can be actuated by means of a servo drive 107 with a cam disk. The compression unit 10 is mounted on the third saddle 103 and is pressed against an upper stop 109 with a pressure of about 10-15N by means of an adjustable spring 108. The third saddle 103 is moved downward against limit switch 110 by the force of the user's finger. Before the final position is not reached, i.e. before the third saddle has been lowered to the position of the limit switch, the next action cannot be initiated. For this purpose, the limit switches are connected to a process controller which controls the activation of the system unit. The system also includes an analysis unit 90 with test strips 91 rotatably mounted on a drive shaft 93 in a holder unit 92. The transmission of the rotational torque from the drive shaft to the carrier unit is accomplished by a belleville spring. The pressure of the test strip on the finger is almost independent of the rotation angle. The pressure is about 1N and this value should not be substantially higher than this value. Excessive pressure closes the punctured passage and also displaces trapped blood volume in the closed, compressed tissue. The servo drive 94 which drives the drive shaft (93) is only partially visible in the selected illustration.

The procedure for carrying out the test:

the lancet is inserted into the lancing device (lancing device 80), the lancing device is clamped (which may be done automatically), and the lancing device is then placed into the holder 82. An unused test strip 91 is placed in the holder unit 92.

The bracket 92 is initially positioned to allow the punch device to move (rock) in the direction of the compression unit 10. Then, the puncturing device is inserted into the compression unit, and when the compression unit is pulled on and pressure is applied, the user can feel the front end of the puncturing device. In this position the pressure exerted by the puncturing device is controlled by the spring 106 (about 2N). The excessive force exerted by the user on the finger will be monitored by means of the spring 108 and limit switch 110, monitoring the entire measurement process 10-15N. The lifting finger measurement is terminated.

If the user's finger is correctly placed, the measurement process begins and the measurement process begins automatically.

The servo drive 107 operates a drive button of the puncturing device 80. Immediately after the puncturing procedure, the puncturing device is removed from the fingertip and fixed in a position in which the analysis unit can be moved without interference. Waiting for 3-10 seconds for accumulated blood volume to emerge from the puncture and form a droplet on the skin surface. After the waiting period, the analytical unit is swung to the skin surface and the opening of the test strip is immersed in the drop of blood. In this process, a maximum pressure of about 1N is regulated by the belleville spring. Once the test area of the test strip is fully used, the monitor notifies the user that the finger can be retracted. The obtained measurement results are displayed on the LCD. This procedure may also be altered somewhat, such as moving the analysis unit to the skin surface and keeping the blood drawn there. In a preferred embodiment, the test strip is monitored for adequate blood infiltration and the user is notified of the monitoring so that the user can remove his or her finger. This procedure can reduce the time for the user to press the body part. In the second procedure described above, the test strip is preferably not pressed against the body, but rather only near the skin surface, where it is infiltrated by the gushing blood.

Claims (18)

1. A system for extracting body fluid from a finger pad of a person, comprising:

-a compressing unit, over which the finger pad is pressed in an initial direction, which transforms a part of the applied pressure into a movement in a second direction, said movement in the second direction having a component perpendicular to the initial direction, so that the compressing unit is laterally compressed and the internal width of the compressing unit is reduced, thereby increasing the internal pressure inside the finger pad,

a puncture device for puncturing a wound in the inner digit of a finger whose internal pressure is increased, for which purpose the compression unit has a pressure-exerting region made of a deformable material.

2. The system of claim 1, wherein the area of applied pressure has an opening with edges against which the finger is pressed, resulting in a reduced internal width of the opening.

3. The system of claim 2, wherein the edge is circular in shape.

4. The system of claim 1, wherein the pressure application area has an opening through which the puncturing device can penetrate to an area where the internal pressure is increased, the area being located on the finger pad.

5. A system according to claim 3, wherein the compression unit has a tapered, tapered region above it and an associated lower region, the lower region being tapered.

6. The system of claim 1, wherein the pressure applying region is formed of an elastomer.

7. A system according to claim 2, wherein the internal width of the edged opening is 4mm or greater prior to application of pressure.

8. System according to claim 1, characterized in that the puncturing device is arranged to be movable in relation to the compression unit.

9. The system of claim 8, wherein the puncturing device is spring-loaded.

10. A system according to claim 1, 8 or 9, wherein the penetration depth of the puncturing means is adjustable.

11. A system according to claim 1 or 8, wherein a sampling device is provided for extracting body fluid.

12. A system according to claim 11, characterized in that the sampling device is arranged to be movable relative to the compression unit.

13. A system according to claim 1, characterized in that an analysis system is integrated which is arranged to determine the concentration of the analyte.

14. The system of claim 13, wherein a control unit is integrated that coordinates the activation of the lancing device and the analysis system.

15. The system of claim 13, wherein the compression unit has an opening through which the analysis system can move to an area of increased internal pressure for collecting body fluid, the area being an area on the finger belly.

16. The system of claim 13, wherein the analytical system comprises at least one test element.

17. A system according to claim 11, wherein the sampling device is a needle or a material with capillary action, said needle or capillary material being connected to the analysis zone and emitting a concentration-dependent signal when the analyte is present.

18. A system for promoting the flow of bodily fluids from the belly of a human finger includes a compression unit for partially converting a pressure applied by the belly of the finger in an initial direction into a movement in a second direction perpendicular to the initial direction, thereby causing the compression unit to be laterally compressed and the internal width of the compression unit to be reduced, thereby increasing the internal pressure of the belly of the finger, wherein the compression unit has a pressure application region made of a deformable material.