US 20050209625 A1
A lancing device where electrical stimulation is applied to a skin sampling site prior to making an incision to achieve at least one of pain masking and bodily fluid engorgement at the site. The electrical stimulation is supplied by a low current high voltage AC signal generator in sufficient quantities to produce vasodialation and/or pain masking.
1. Apparatus for obtaining a sample of bodily fluid through the skin, said apparatus comprising:
a plurality of electrodes on said housing and positioned to contact a site on the skin,
an electrical signal generator for applying electrical energy to said electrodes, said electrical signal generator supplying electrical energy in sufficient quantity to stimulate the skin at said site to accomplish at least one of pain masking and bodily fluid engorgement at said site, and
a skin-lancing device mounted in said housing for directing a skin-lancing medium against the skin at said site to form an incision therein subsequent to the application of said electrical energy.
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15. A method for obtaining a sample of bodily fluid through the skin, said method comprising:
applying electrical energy to a sampling site on said skin of sufficient quantity to stimulate the skin at said site to accomplish at least one of pain masking and bodily fluid engorgement at said site, and
subsequently making an incision at said site to remove a sample of bodily fluid.
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The present invention relates to devices and methods for obtaining samples of blood and other fluids from the body for analysis or processing.
The wide-spread application of devices for extracting samples of bodily fluids for analysis such as determining blood glucose level has led to significant activity in the field to address several problems and issues. These are the problems of pain when the skin is pierced by a lance and the problem of insuring a sufficient quantity of blood at the surface to obtain a proper sample size. Many proposals have been made to achieve these ends.
In terms of pain management there are there have been developments relative to the shape of the lance itself. These have involved depth of cuts so that the depth is the minimum necessary to extract a sample. In addition, the rate of incision has been controlled so that with a faster incision, pain is diminished.
Other activities have focused on pain masking by using vibrators and even patient distractions so that a patient is not focusing on the pain that will be experienced during the process.
A second area of effort focuses on stimulating increased presence of blood so that at least a minimum blood sample size is collected after lancing for accurate testing. Some research has focused on ways of palpating the skin to express additional blood, either manually or by various mechanisms. Other researchers have proposed using vibration, ultrasonics and other stimulation to increase blood flow. However, such devices are either too crude and simplistic or are overly complicated and expensive.
The above activity is brought into increased focus when alternate site testing (AST) is adopted to sample bodily fluids from locations other than the fingers. Both pain minimization and blood engorgement need to be managed.
The invention, in one form, relates to a device for obtaining a sample of bodily fluid through the skin. The device comprises a housing and electrodes on the housing positioned to contact a site on the skin. An electrical signal generator applies electrical energy to the electrodes in sufficient quantity to stimulate the skin at the site to accomplish at least one of pain masking and bodily fluid engorgement at the site. A skin-lancing device mounted in the housing directs a skin-lancing medium against the skin at the site to form an incision therein subsequent to the application of electrical energy.
In another form, the invention relates to a method obtaining a sample of bodily fluid through the skin. The method comprises applying electrical energy to a sampling site on the skin of sufficient quantity to stimulate the skin at the site to accomplish at least one of pain masking and bodily fluid engorgement at the site. Subsequently, an incision is formed at the site to remove a sample of bodily fluid.
For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated herein and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended. Any alterations and further modifications in the described processes, systems or devices, and any further applications of the principles of the invention as described herein, are contemplated as would normally occur to one skilled in the art to which the invention relates.
The present invention uses electrical treatment of a skin sampling site to achieve one or both of pain masking and blood engorgement before a lancing device causes an incision to be made for blood sampling.
Lancet actuator 22 may take one of many different forms to achieve a controlled rate of displacement and penetration depth for the lancet 28. Lancet actuator 22 may be mechanical in form using a spring-like device. It may also be electrically or pneumatically actuated. As herein shown, a capillary passage 35 leads from the mouth of passage 34 adjacent the incision of lancet 28 to a sensor 37 which gives an indication of bodily fluid parameter or condition through optical read-out 39. Alternatively, lancet 28 may to pierce the skin so that a sufficient quantity of blood may accumulate on the skin for application to a test strip (not shown). It should be noted that to those skilled in the art, the unit may be used to collect blood samples through the lancet 28 and provide still another way to integrate the testing process.
The advantages and features of the present invention will be seen to be equally applicable to the range of devices used to sample blood for glucose measurement and other applications. More specifically, the invention would be applicable to devices that sample and analyze the blood in a single unit.
In accordance with the present invention, the lancing device cap 14 has a plurality of electrodes 30 and 32 grouped within sets. The electrodes 30 and 32 are positioned in an array around the periphery of an opening 34 for lancet 28. As described below, the cap 14 may take the form shown in
As shown in
Signal generator 40, as illustrated, is of a type that generates a high voltage AC wave. The voltage level can be approximately from 10 to 25 kilovolts. The frequency preferably is 20 Hz. The signal generator controller 44 can be adapted to control the signal generator 40 through a range of frequencies, voltages and at low current (i.e. 100 miliamps) as appropriate for the applications described below.
The present invention relies on the principle of electrical treatment prior to the lancing of the skin to accomplish at least one of pain masking and bodily fluid or blood engorgement.
In one aspect, the electrical pulses stimulate the peripheral terminals of sensory neurons in the body, which cause the release of bioactive substances. These substances for the most part are neuropeptides; substance P and calcitonian gene related peptide. They in turn act on target cells in the periphery of the applied area such as masked cells, immune cells and smooth muscle producing inflammation. This is characterized by redness and warmth, an indication of vasodialation. This phenomenon is known as neurogenetic inflammation.
It has been determined that application of electrical stimulus for a period of approximately 30 seconds will produce vasodialation. Accordingly, after the application of the electrical energy, the lancet 28 is actuated to pierce the skin and produce a quantity of blood which is enhanced by the pretreatment of the surface to produce vasodilatation. In tests outlined in table 1, there is as shown a 77% increase in average blood volume and a 16% increase in the success rate to obtain 0.75 microliters of a sample. For this test, the voltage level was 16 kilovolts at 20 Hz. It should be apparent to those skilled in the art that the electrical parameters set forth in this description are for illustration purposes only based on current investigations and are not to be construed or interpreted as in any way limiting the range of electrical parameters applied within the scope of the present invention.
The success rate can further be enhanced by using an expression cap shown in
In order for electrical stimulation to be used to mask pain, the electrical energy is applied for a longer duration prior to making the incision on the skin. This electrical power can be used through the same electrode pairs shown in
Using either array, the electrodes deliver electrical stimulation to the area to be lanced. This electrical stimulation, depending upon its nature and character, stimulates the sensory neutrons which manipulate the transmission of signals of afferent information to the spinal cord. Electrical stimulation can target the A-delta and C-fibers which deplete neuropeptides content in the terminal ends of the fibers or target the A-beta fiber causing an abundance of signals to be released. The type of outcome is dependent upon the type and intensity of the electrical stimulus such as pulse rate and duration of applied stimulus. This prevents the neuron's ability to transfer information to the central nervous system with respect to trauma or pain to tissues. The stimulus may also target A-beta fibers, which causes an abundance of neuropeptides being released. A-beta fibers are associated with the detection of pressure. As the lancing occurs, the signals transmitted by the A-delta and C-fibers are clouded by the abundance of A-beta fiber signals. This phenomenon tends to reduce the sensitivity of neociceptive pain. To insure adaptability to as many users as possible because of different individual stimulation thresholds, the device is adjustable for the intensity and pulse rate.
Table 2 shows the pain rating with and without electrical stimulation. The electrical stimulation was at 20 Hz for at least 60 seconds prior to lancing. A reduction and/or increase in tolerance of pain were achieved with electrical stimulation. It should be apparent to those skilled in the art that the parameters set forth in this description are for illustration purposes only based on current investigation and are not to be construed or interpreted as in any way limiting the range of electrical parameters applied within the scope of present invention.
When the device is intended to be used for both pain masking and engorgement of bodily fluids, the electrical stimulation is applied for approximately 60 seconds and above. After 30 seconds the engorgement of the site with blood is achieved and after approximately 60 seconds the pain masking is realized. Once the pain masking is achieved, the lancing device is fired to lance the skin. Subsequent to lancing, the skin contacting surface 52 may be employed to express bodily fluid or blood from the incision for application to a test strip. Alternatively, different forms of lancing devices may be used which extract a sample for delivery to another test device.
While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only the preferred embodiment has been shown and described and that all changes and modifications that come within the spirit of the invention are desired to be protected.