Surgery – Diagnostic testing – Liquid collection
Reexamination Certificate
2000-07-12
2004-01-20
Denion, Thomas (Department: 3748)
Surgery
Diagnostic testing
Liquid collection
C600S573000, C606S181000
Reexamination Certificate
active
06679852
ABSTRACT:
BACKGROUND AND SUMMARY OF THE INVENTION
The present invention concerns a system for withdrawing body fluid from a part of the body, especially the finger pad. Body fluids are primarily withdrawn for a subsequent analysis in order to diagnose diseases or to monitor the metabolic state of a patient. Such a withdrawal is carried out especially by diabetics in order to determine the blood sugar concentration. The aim of such a blood-sugar check that is usually carried out several times daily is to avoid hypoglycaemic states as well as hyperglycaemic states. In the case of a hypoglycaemia the patient can fall into a coma and even die since the brain is no longer adequately supplied with glucose. In contrast hyperglycaemic states can lead to long-term side-effects such as blindness, gangrenes and such like.
Consequently a frequent monitoring of the blood sugar level is an undisputed necessity. It is therefore obvious that there is an urgent need for sampling systems which are easy to operate by the user and are above all largely free of pain.
Already blood sampling systems have been known for some time in the prior art which allow the patient or hospital staff to carry out a withdrawal in a simple manner. A device suitable for this is for example the commercially available SOFTCLIX® whose manner of operation is described in U.S. Pat. No. 5,318,584. This device provides an adjustment means for the depth to which a lancet is inserted into the tissue. Hence the patient can select the minimum puncture depth which enables a just sufficient quantity of blood to be obtained for a subsequent analysis and thus keep the incision pain very low. After the patient has produced a skin opening by piercing, he has to massage or press his finger in order to draw sufficient blood from the puncture wound especially with small puncture depths. This operation which is frequently referred to as “milking” by diabetics can hitherto only be avoided when the puncture is very deep and correspondingly unpleasant for the patient and can lead to major scarring on the sensitive finger tips. Devices known in the prior art attempt to stimulate the outflow of blood by applying a vacuum but this has proven to be not very efficient.
Devices are also known in the prior art in which a so-called stimulator with a ring depresses the skin surface surrounding an incision site. Such a device for obtaining interstitial liquid is described for example in U.S. Pat. No. 5,582,184. The document shows that pressure is only applied from one side of the body and hence the body part is not enclosed by the device. Only small amounts of fluid can be obtained with the device that are not adequate for commercial analytical systems.
Another device is known from U.S. Pat. No. 5,857,983 in which a cannula is inserted into the skin surface and the skin surface surrounding the site of incision is repeatedly depressed using a so-called stimulator in order to press body fluid into the cannula. Like the above-mentioned document a rigid ring is used in this device to depress the skin surface. The amounts of body fluid that can be obtained with this device are also small and thus inadequate for conventional analytical systems.
A device is known from the document U.S. Pat. No. 3,626,929 in which a finger is clamped before blood withdrawal between a lever and a finger support. The finger support is moved by a motor in order to result in a massaging proximal to the incision site. For the withdrawal the user's finger is pressed against a flexible cap in which needles and a fluid channel are located. A disadvantage of this device is that the needles for the withdrawal remain in the body and that in this state the finger support is moved. This results in movement of the needles in the finger which usually leads to considerable pain. In addition it is extremely unlikely that blood will emerge while there is a needle in the finger since the channel is closed by the needle. A collecting container is shown in
FIGS. 11 and 12
which has a flexible pressure-application region. However, due to the shape of the pressure-application region which widens conically towards the finger there is no conversion of a primary pressure-application movement into a lateral movement which squeezes the sampling region together.
Systems are also known in the prior art in which a finger from which blood is to be withdrawn is inserted into an inflatable cuff in such a manner that the finger tip protrudes from the cuff. Inflating the cuff ties off the finger which leads to blood congestion. Such devices are described in the Japanese documents JP 9313465 and JP 9266889. However, users find these devices disagreeable since inflation of the cuff is controlled by the device and hence deprives the user of control over his finger. These devices also have technical disadvantages since pumps etc. are required to produce blood congestion which complicate the apparatus and also have quite considerable energy requirements.
A device for tying off the finger tip is described in the U.S. Pat. No. 5,893,870. It is intended that the user himself carries out the tying off and then removes blood from the finger tip with a lancing device. In this procedure the user consequently has to carry out numerous handling steps with the result that the process has hardly any advantage over the current conventional procedure in which firstly an incision is made and the finger is subsequently massaged by the user.
The object of the present invention was to provide a system for withdrawing body fluid which, using small puncture depths, yields an adequate amount of body fluid, in particular blood. An additional object of the invention was to provide a system which can be easily operated and has a simple construction. Simplicity in this sense means in particular that the number of operating steps that are required is as small as possible.
The present invention concerns a system for withdrawing body fluid from a part of the body in particular a finger pad comprising the following elements:
a deformable compression unit against which the part of the body is pressed in a primary direction and partially converts the applied pressure into a movement in a secondary direction with a component perpendicular to the primary direction such that the internal pressure is increased in a region of the body part, and the compression unit at least partially encloses the body part,
a perforation device, in particular a lancet or cannula, to produce a body opening in the area of the increased internal pressure.
Use of the compression unit according to the invention replaces the above-mentioned milking movement for squeezing out blood from the incision site in a simple and comfortable manner for the user. The compression unit not only yields larger quantities of body fluid than is the case with the compression devices of the prior art but the compression and withdrawal process is also considerably more pleasant for the patient. This is due to the fact that the compression unit fits snugly around the body part, in particular a finger. A further contributing factor is that the compression unit enables adequate quantities of body fluid to be obtained even with very small puncture depths.
The system according to the invention can be used particularly advantageously to obtain capillary blood from the finger pad. In addition it is also possible to withdraw blood or interstitial fluid from other body parts.
An essential element of the system is the compression unit which results in the body part being squeezed together not only in the direction of the primary applied pressure but also results in the applied pressure being at least partially diverted such that a squeezing occurs with components of force transverse to the primary direction and the compression unit (at least) partially encloses the body part. The mode of action of this advantageous compression is elucidated later on the basis of the embodiments. The compression unit produces an increase of the internal pressure in a first region
51
of the body part. This first region
Deck Frank
Forster Richard
Schmelzeisen-Redeker Guenther
Weiss Thomas
Chang Ching
Denion Thomas
Knauer Richard T.
Roche Diagnostics Corporation
Woodburn Jill L.
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